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Showing 1 - 200 of 3043 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 20, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 18, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 83, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 23, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 27, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 4)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 5, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 332, SJR: 0.726, h-index: 43)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Biomaterialia     Hybrid Journal   (Followers: 25, SJR: 2.02, h-index: 104)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 1)
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.172, h-index: 29)
Acta Haematologica Polonica     Free   (SJR: 0.123, h-index: 8)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.604, h-index: 38)
Acta Materialia     Hybrid Journal   (Followers: 211, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 9, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription   (Followers: 1)
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 23, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.059, h-index: 77)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 4)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 3)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 4, SJR: 0.383, h-index: 19)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 2)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 5, SJR: 0.141, h-index: 3)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 4, SJR: 0.112, h-index: 2)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 3)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.967, h-index: 57)
Addictive Behaviors     Hybrid Journal   (Followers: 15, SJR: 1.514, h-index: 92)
Addictive Behaviors Reports     Open Access   (Followers: 5)
Additive Manufacturing     Hybrid Journal   (Followers: 8, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 131, SJR: 5.2, h-index: 222)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.265, h-index: 53)
Advanced Powder Technology     Hybrid Journal   (Followers: 16, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.299, h-index: 15)
Advances in Agronomy     Full-text available via subscription   (Followers: 15, SJR: 2.071, h-index: 82)
Advances in Anesthesia     Full-text available via subscription   (Followers: 25, SJR: 0.169, h-index: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 6, SJR: 1.054, h-index: 35)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 10, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22, SJR: 1.286, h-index: 49)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 16, SJR: 3.31, h-index: 42)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.277, h-index: 43)
Advances in Botanical Research     Full-text available via subscription   (Followers: 3, SJR: 0.619, h-index: 48)
Advances in Cancer Research     Full-text available via subscription   (Followers: 25, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 0.9, h-index: 30)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 2.139, h-index: 42)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 24, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 16, SJR: 0.223, h-index: 22)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 4)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Ecological Research     Full-text available via subscription   (Followers: 41, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 25, SJR: 0.486, h-index: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 40, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 47, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Genetics     Full-text available via subscription   (Followers: 15, SJR: 2.558, h-index: 54)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 2.325, h-index: 20)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 25)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.396, h-index: 27)
Advances in Immunology     Full-text available via subscription   (Followers: 35, SJR: 4.152, h-index: 85)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 1.132, h-index: 42)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 3, SJR: 1.274, h-index: 27)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 5)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 4)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.764, h-index: 15)
Advances in Lipobiology     Full-text available via subscription   (Followers: 2)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
Advances in Marine Biology     Full-text available via subscription   (Followers: 16, SJR: 1.645, h-index: 45)
Advances in Mathematics     Full-text available via subscription   (Followers: 10, SJR: 3.261, h-index: 65)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.489, h-index: 25)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.44, h-index: 51)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 22)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 4)
Advances in Oncobiology     Full-text available via subscription   (Followers: 3)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15, SJR: 2.885, h-index: 45)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.148, h-index: 11)
Advances in Parasitology     Full-text available via subscription   (Followers: 7, SJR: 2.37, h-index: 73)
Advances in Pediatrics     Full-text available via subscription   (Followers: 24, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 13)
Advances in Pharmacology     Full-text available via subscription   (Followers: 15, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 8)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 19, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 60)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5, SJR: 0.478, h-index: 32)
Advances in Radiation Oncology     Open Access  
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 2, SJR: 0.1, h-index: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 343, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Surgery     Full-text available via subscription   (Followers: 7, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 30, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 15)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 43, SJR: 2.408, h-index: 94)
Aeolian Research     Hybrid Journal   (Followers: 5, SJR: 0.973, h-index: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 307, SJR: 0.816, h-index: 49)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.318, h-index: 36)
African J. of Emergency Medicine     Open Access   (Followers: 5, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 8, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 406, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 30, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 38, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access  
Agriculture and Natural Resources     Open Access   (Followers: 1)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 53, SJR: 1.879, h-index: 120)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.434, h-index: 14)
Air Medical J.     Hybrid Journal   (Followers: 5, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 9, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 6)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.436, h-index: 12)
Alexandria J. of Medicine     Open Access  
Algal Research     Partially Free   (Followers: 8, SJR: 2.05, h-index: 20)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.46, h-index: 29)
Allergology Intl.     Open Access   (Followers: 4, SJR: 0.776, h-index: 35)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 7, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 48, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 5)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 3)
American Heart J.     Hybrid Journal   (Followers: 48, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 45, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 38, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 6, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 16, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 31, SJR: 8.769, h-index: 256)
American J. of Infection Control     Hybrid Journal   (Followers: 24, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 33, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 46, SJR: 2.023, h-index: 189)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 191, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 54, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 3)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.249, h-index: 88)
American J. of Otolaryngology     Hybrid Journal   (Followers: 23, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 26, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 21, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 34, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 5)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 55, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 9)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 2, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 38, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 163, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 8, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 1)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 22, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access  
Animal Behaviour     Hybrid Journal   (Followers: 157, SJR: 1.907, h-index: 126)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 5, SJR: 1.151, h-index: 83)
Animal Reproduction Science     Hybrid Journal   (Followers: 5, SJR: 0.711, h-index: 78)
Annales d'Endocrinologie     Full-text available via subscription   (Followers: 1, SJR: 0.394, h-index: 30)
Annales d'Urologie     Full-text available via subscription  
Annales de Cardiologie et d'Angéiologie     Full-text available via subscription   (SJR: 0.177, h-index: 13)
Annales de Chirurgie de la Main et du Membre Supérieur     Full-text available via subscription  
Annales de Chirurgie Plastique Esthétique     Full-text available via subscription   (Followers: 2, SJR: 0.354, h-index: 22)
Annales de Chirurgie Vasculaire     Full-text available via subscription   (Followers: 1)

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Journal Cover Analytica Chimica Acta
  [SJR: 1.548]   [H-I: 152]   [38 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0003-2670 - ISSN (Online) 1873-4324
   Published by Elsevier Homepage  [3043 journals]
  • Ion mobility spectrometry combined with ultra performance liquid
           chromatography/mass spectrometry for metabolic phenotyping of urine:
           Effects of column length, gradient duration and ion mobility spectrometry
           on metabolite detection
    • Authors: Paul D. Rainville; Ian D. Wilson; Jeremy K. Nicholson; Giorgis Issacs; Lauren Mullin; James I. Langridge; Robert S. Plumb
      Pages: 1 - 8
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Paul D. Rainville, Ian D. Wilson, Jeremy K. Nicholson, Giorgis Issacs, Lauren Mullin, James I. Langridge, Robert S. Plumb
      The need for rapid and efficient high throughput metabolic phenotyping (metabotyping) in metabolomic/metabonomic studies often requires compromises to be made between analytical speed and metabolome coverage. Here the effect of column length (150, 75 and 30 mm) and gradient duration (15, 7.5 and 3 min respectively) on the number of features detected when untargeted metabolic profiling of human urine using reversed-phase gradient ultra performance chromatography with, and without, ion mobility spectrometry, has been examined. As would be expected, reducing column length from 150 to 30 mm, and gradient duration, from 15 to 3 min, resulted in a reduction in peak capacity from 311 to 63 and a similar reduction in the number of features detected from over ca. 16,000 to ca. 6500. Under the same chromatographic conditions employing UPLC/IMS/MS to provide an additional orthogonal separation resulted in an increase in the number of MS features detected to nearly 20,000 and ca. 7500 for the 150 mm and the 30 mm columns respectively. Based on this limited study the potential of LC/IMS/MS as a tool for improving throughput and increasing metabolome coverage clearly merits further in depth study.
      Graphical abstract image

      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.020
      Issue No: Vol. 982 (2017)
  • Class-modelling in food analytical chemistry: Development, sampling,
           optimisation and validation issues – A tutorial
    • Authors: Paolo Oliveri
      Pages: 9 - 19
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Paolo Oliveri
      Qualitative data modelling is a fundamental branch of pattern recognition, with many applications in analytical chemistry, and embraces two main families: discriminant and class-modelling methods. The first strategy is appropriate when at least two classes are meaningfully defined in the problem under study, while the second strategy is the right choice when the focus is on a single class. For this reason, class-modelling methods are also referred to as one-class classifiers. Although, in the food analytical field, most of the issues would be properly addressed by class-modelling strategies, the use of such techniques is rather limited and, in many cases, discriminant methods are forcedly used for one-class problems, introducing a bias in the outcomes. Key aspects related to the development, optimisation and validation of suitable class models for the characterisation of food products are critically analysed and discussed.
      Graphical abstract image

      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.013
      Issue No: Vol. 982 (2017)
  • Revealing the biography of a hidden medieval manuscript using synchrotron
           and conventional imaging techniques
    • Authors: E. Pouyet; S. Devine; T. Grafakos; R. Kieckhefer; J. Salvant; L. Smieska; A. Woll; A. Katsaggelos; O. Cossairt; M. Walton
      Pages: 20 - 30
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): E. Pouyet, S. Devine, T. Grafakos, R. Kieckhefer, J. Salvant, L. Smieska, A. Woll, A. Katsaggelos, O. Cossairt, M. Walton
      Reading the content of hidden texts from ancient manuscripts has become an increasingly important endeavor thanks to the variety of non-destructive analytical tools and image processing routines available for this task. In this study, portable macro X-Ray Fluorescence (MA-XRF-tube), Visible Hyperspectral Imaging (HSI) together with Synchrotron based macro X-Ray Fluorescence (MA-XRF-SR) are combined with signal processing methods to reveal the biography of a degraded manuscript recycled as binding material for a 16th century printed edition of Hesiod's Works and Days. The analytical techniques allow visualizing the hidden text, revealing passages from the Institutes Justinian, a 6th century A.D codification of the Roman Law, with further marginal comments on medieval Canon Law. In addition, the identification of the materials (e.g. pigments, inks) part of the original manuscript together with their sequence of use are revealed: i) the preparation of the parchment using a Ca-based preparation layer, ii) drawing of ruled guide lines, using a Pb-based pen or ink, iii) writing of the main text using a rich Fe-gall ink with modulating color pigments (Hg-, Cu- and Pb- based) and iv) addition of two types of comments to the main text, one of the ink used for the comments being a Fe-gall ink rich in Cu.
      Graphical abstract image

      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.016
      Issue No: Vol. 982 (2017)
  • Multi-energy calibration applied to atomic spectrometry
    • Authors: Alex Virgilio; Daniel A. Gonçalves; Tina McSweeney; José A. Gomes Neto; Joaquim A. Nóbrega; George L. Donati
      Pages: 31 - 36
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Alex Virgilio, Daniel A. Gonçalves, Tina McSweeney, José A. Gomes Neto, Joaquim A. Nóbrega, George L. Donati
      Multi-energy calibration (MEC) is a novel strategy that explores the capacity of several analytes of generating analytical signals at many different wavelengths (transition energies). Contrasting with traditional methods, which employ a fixed transition energy and different analyte concentrations to build a calibration plot, MEC uses a fixed analyte concentration and multiple transition energies for calibration. Only two calibration solutions are required in combination with the MEC method. Solution 1 is composed of 50% v v−1 sample and 50% v v−1 of a standard solution containing the analytes. Solution 2 has 50% v v−1 sample and 50% v v−1 blank. Calibration is performed by running each solution separately and monitoring the instrument response at several wavelengths for each analyte. Analytical signals from solutions 1 and 2 are plotted on the x-axis and y-axis, respectively, and the analyte concentration in the sample is calculated from the slope of the resulting calibration curve. The method has been applied to three different atomic spectrometric techniques (ICP OES, MIP OES and HR-CS FAAS). Six analytes were determined in complex samples (e.g. green tea, cola soft drink, cough medicine, soy sauce, and red wine), and the results were comparable with, and in several cases more accurate than, values obtained using the traditional external calibration, internal standardization, and standard additions methods. MEC is a simple, fast and efficient matrix-matching calibration method. It may be applied to any technique capable of simultaneous or fast sequential monitoring of multiple analytical signals.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.040
      Issue No: Vol. 982 (2017)
  • Improved variable reduction in partial least squares modelling by
           Global-Minimum Error Uninformative-Variable Elimination
    • Authors: Jan P.M. Andries; Yvan Vander Heyden; Lutgarde M.C. Buydens
      Pages: 37 - 47
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Jan P.M. Andries, Yvan Vander Heyden, Lutgarde M.C. Buydens
      The calibration performance of Partial Least Squares regression (PLS) can be improved by eliminating uninformative variables. For PLS, many variable elimination methods have been developed. One is the Uninformative-Variable Elimination for PLS (UVE-PLS). However, the number of variables retained by UVE-PLS is usually still large. In UVE-PLS, variable elimination is repeated as long as the root mean squared error of cross validation (RMSECV) is decreasing. The set of variables in this first local minimum is retained. In this paper, a modification of UVE-PLS is proposed and investigated, in which UVE is repeated until no further reduction in variables is possible, followed by a search for the global RMSECV minimum. The method is called Global-Minimum Error Uninformative-Variable Elimination for PLS, denoted as GME-UVE-PLS or simply GME-UVE. After each iteration, the predictive ability of the PLS model, built with the remaining variable set, is assessed by RMSECV. The variable set with the global RMSECV minimum is then finally selected. The goal is to obtain smaller sets of variables with similar or improved predictability than those from the classical UVE-PLS method. The performance of the GME-UVE-PLS method is investigated using four data sets, i.e. a simulated set, NIR and NMR spectra, and a theoretical molecular descriptors set, resulting in twelve profile-response (X-y) calibrations. The selective and predictive performances of the models resulting from GME-UVE-PLS are statistically compared to those from UVE-PLS and 1-step UVE, one-sided paired t-tests. The results demonstrate that variable reduction with the proposed GME-UVE-PLS method, usually eliminates significantly more variables than the classical UVE-PLS, while the predictive abilities of the resulting models are better. With GME-UVE-PLS, a lower number of uninformative variables, without a chemical meaning for the response, may be retained than with UVE-PLS. The selectivity of the classical UVE method thus can be improved by the application of the proposed GME-UVE method resulting in more parsimonious models.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.001
      Issue No: Vol. 982 (2017)
  • Automatic feed phase identification in multivariate bioprocess profiles by
           sequential binary classification
    • Authors: Ramin Nikzad-Langerodi; Edwin Lughofer; Susanne Saminger-Platz; Thomas Zahel; Patrick Sagmeister; Christoph Herwig
      Pages: 48 - 61
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Ramin Nikzad-Langerodi, Edwin Lughofer, Susanne Saminger-Platz, Thomas Zahel, Patrick Sagmeister, Christoph Herwig
      In this paper, we propose a new strategy for retrospective identification of feed phases from online sensor-data enriched feed profiles of an Escherichia Coli (E. coli) fed-batch fermentation process. In contrast to conventional (static), data-driven multi-class machine learning (ML), we exploit process knowledge in order to constrain our classification system yielding more parsimonious models compared to static ML approaches. In particular, we enforce unidirectionality on a set of binary, multivariate classifiers trained to discriminate between adjacent feed phases by linking the classifiers through a one-way switch. The switch is activated when the actual classifier output changes. As a consequence, the next binary classifier in the classifier chain is used for the discrimination between the next feed phase pair etc. We allow activation of the switch only after a predefined number of consecutive predictions of a transition event in order to prevent premature activation of the switch and undertake a sensitivity analysis regarding the optimal choice of the (time) lag parameter. From a complexity/parsimony perspective the benefit of our approach is three-fold: i) The multi-class learning task is broken down into binary subproblems which usually have simpler decision surfaces and tend to be less susceptible to the class-imbalance problem. ii) We exploit the fact that the process follows a rigid feed cycle structure (i.e. batch-feed-batch-feed) which allows us to focus on the subproblems involving phase transitions as they occur during the process while discarding off-transition classifiers and iii) only one binary classifier is active at the time which keeps effective model complexity low. We further use a combination of logistic regression and Lasso (i.e. regularized logistic regression, RLR) as a wrapper to extract the most relevant features for individual subproblems from the whole set of high-dimensional sensor data. We train different soft computing classifiers, including decision trees (DT), k-nearest neighbors (k-NN), support vector machines (SVM) and an own developed fuzzy classifier and compare our method with conventional multi-class ML. Our results show a remarkable out-performance of the here proposed method over static ML approaches in terms of accuracy and robustness. We achieved close to error free feed phase classification while reducing the misclassification rates in 17 out of 20 investigated test cases in the range between 39% and 98.2% depending on feature set and classifier architecture. Models trained on features based on selection by RLR significantly outperformed those trained on features suggested by experts and their predictive performance was considerably less affected by the choice of the lag parameter.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.034
      Issue No: Vol. 982 (2017)
  • A label-free genetic biosensor for diabetes based on AuNPs decorated ITO
           with electrochemiluminescent signaling
    • Authors: Suyan Zhai; Chen Fang; Jilin Yan; Qun Zhao; Yifeng Tu
      Pages: 62 - 71
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Suyan Zhai, Chen Fang, Jilin Yan, Qun Zhao, Yifeng Tu
      The variation of I27L gene closely relates to increasing risk of type 2 diabetes, thus it is greatly significant to develop various methods for its identification or monitoring. We report here a novel label-free electrochemiluminescent (ECL) biosensor for simple and effective determination of I27L gene based on Au nanoparticles functionalized ITO electrode. The ECL technique is employed to monitor the hybridization of DNA strands by measuring the changes of its intensity. Here, the ECL signal was quenched by blocked access of probe (luminol anion) owing to the electrostatic repulsion of negatively charged sensor surface and the space resistance. The quantification of target strand can be directly realized by calibrating the quenched ECL signal toward its logarithm concentration in good linearity within the range from 1.0 × 10−11 to 1.0 × 10−7 M and a detection limit of 8.1 × 10−12 M. In addition, the biosensor exhibited good stability, excellent reproducibility and outstanding selectivity against one-base mismatched strand. What's more, the simple, low-cost, sensitive device could be easily miniaturized, makes it as an attractive candidate for integrating into portable platforms for point-of-care molecular diagnostics.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.028
      Issue No: Vol. 982 (2017)
  • A solid-contact potassium-selective electrode with MoO2 microspheres as
           ion-to-electron transducer
    • Authors: Xianzhong Zeng; Wei Qin
      Pages: 72 - 77
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Xianzhong Zeng, Wei Qin
      A solid-contact ion-selective electrode (SC-ISE) for potassium with MoO2 microspheres as ion-to-electron transducer is described. MoO2 microsphers can be synthesized via the reduction of MoO3 nanobelts in an isopropanol solvent with a mild process, and the obtained MoO2 microspheres have been characterized by X-ray diffraction and field-emission scanning electron microscopy. With the application of MoO2 microspheres, the newly fabricated SC-ISE for K+ exhibits a stable and rapid potential response. A near Nernstian slope of 55 mV/decade to potassium activities in the range of 10−5 ‒ 10−3 M is found and the detection limit is 10−5.5 M. Impedance spectra and chronopotentiometry results show that a smaller resistance together with a larger double layer capacitance is guaranteed due to the introduction of the intermediate layer of MoO2 microspheres. Additionally, light, O2 and CO2 do not induce significant influences to the present SC-ISE, and a reduced water layer between the ion selective membrane and the underlying conductor is formed. Thus, it is clear that MoO2 microspheres, as metallic analogues, can be used as a good candidate for the new type of transducing layer in SC-ISEs.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.032
      Issue No: Vol. 982 (2017)
  • Exploring pralidoxime chloride as a universal electrochemical probe for
           organophosphorus pesticides detection
    • Authors: Qiqi Zheng; Yuan Chen; Kai Fan; Jian Wu; Yibin Ying
      Pages: 78 - 83
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Qiqi Zheng, Yuan Chen, Kai Fan, Jian Wu, Yibin Ying
      An electrochemical method based on non-enzymatic inhibition for the determination of organophosphorus pesticide (OPPs) using pralidoxime chloride (PAM-Cl) as a universal electrochemical probe was reported. Cyclic voltammetry was performed to characterize the redox properties of pralidoxime and OPPs. Differential pulse voltammetry (DPV) was carried out to analyze the influence of anion (chloride and iodide ions), to optimize the pH of testing condition, and to explore the relationship between pralidoxime and OPPs. The results showed that iodide ion generated an anodic peak close to the peak of pralidoxime, which would interfere in the detection of OPPs. Phosphate buffer solution (pH 7.0) was chosen because of its high peak current and low peak potential when testing PAM-Cl by DPV. Chlorpyrifos, fenthion, and methyl parathion were examples of three existing OPPs detection methods. The peak current of PAM-Cl decreased along with the increase of concentration of OPPs in the solution. The limit of detection was 0.018 μM, 0.100 μM, and 0.215 μM, respectively. It was the first time for PAM-Cl to be used as a universal electrochemical probe to develop a simple, cheap and stable method for OPPs detection.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.006
      Issue No: Vol. 982 (2017)
  • Systematic comparison of exosomal proteomes from human saliva and serum
           for the detection of lung cancer
    • Authors: Yan Sun; Sha Liu; Zhi Qiao; Zhi Shang; Zhijun Xia; Xiaomin Niu; Liqiang Qian; Yan Zhang; Liuyin Fan; Cheng-Xi Cao; Hua Xiao
      Pages: 84 - 95
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Yan Sun, Sha Liu, Zhi Qiao, Zhi Shang, Zhijun Xia, Xiaomin Niu, Liqiang Qian, Yan Zhang, Liuyin Fan, Cheng-Xi Cao, Hua Xiao
      Circulating tumor exosomes harbor plenty of cancer biological information, which have emerged as promising targets for cancer early detection and diagnosis. Human serum and saliva are unique diagnostic body fluids, which contain numerous circulating exosomes. It is necessary to establish standardized isolation method and compare their proteome profiling for translational medicine. High abundant proteins in these body fluids were removed before exosomes isolation and obtained exosomes were further confirmed by morphology analysis and surface biomarker test. Label free quantification was applied to systematically compare the protein profiling in saliva and serum exosomes. 319 and 994 exosomal proteins were identified from saliva and serum by LC-MS/MS, respectively. To explore their utility for cancer proteomics, we systematically compared the proteome of saliva and serum exosomes from healthy subjects and lung cancer patients. In particular, 11 potential candidates were coincidently discovered in both body fluids of lung cancer patients. Our finding enforced the hypothesis that cancer related proteins were presented in saliva and serum exosomes, which promoted the unique features of exosomes in our body fluids. A circulating exosomes based body fluid test could be easily established for monitoring cancer once these candidates were validated.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.005
      Issue No: Vol. 982 (2017)
  • Integrated preservation and sample clean up procedures for studying water
           ingestion by recreational swimmers via urinary biomarker determination
    • Authors: Ricardo Cantú; Jody A. Shoemaker; Catherine A. Kelty; Larry J. Wymer; Thomas D. Behymer; Alfred P. Dufour; Matthew L. Magnuson
      Pages: 104 - 111
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Ricardo Cantú, Jody A. Shoemaker, Catherine A. Kelty, Larry J. Wymer, Thomas D. Behymer, Alfred P. Dufour, Matthew L. Magnuson
      The use of cyanuric acid as a biomarker for ingestion of swimming pool water may lead to quantitative knowledge of the volume of water ingested during swimming, contributing to a better understanding of disease resulting from ingestion of environmental contaminants. When swimming pool water containing chlorinated cyanurates is inadvertently ingested, cyanuric acid is excreted quantitatively within 24 h as a urinary biomarker of ingestion. Because the volume of water ingested can be quantitatively estimated by calculation from the concentration of cyanuric acid in 24 h urine samples, a procedure for preservation, cleanup, and analysis of cyanuric acid was developed to meet the logistical demands of large scale studies. From a practical stand point, urine collected from swimmers cannot be analyzed immediately, given requirements of sample collection, shipping, handling, etc. Thus, to maintain quality control to allow confidence in the results, it is necessary to preserve the samples in a manner that ensures as quantitative analysis as possible. The preservation and clean-up of cyanuric acid in urine is complicated because typical approaches often are incompatible with the keto-enol tautomerization of cyanuric acid, interfering with cyanuric acid sample preparation, chromatography, and detection. Therefore, this paper presents a novel integration of sample preservation, clean-up, chromatography, and detection to determine cyanuric acid in 24 h urine samples. Fortification of urine with cyanuric acid (0.3–3.0 mg/L) demonstrated accuracy (86–93% recovery) and high reproducibility (RSD < 7%). Holding time studies in unpreserved urine suggested sufficient cyanuric acid stability for sample collection procedures, while longer holding times suggested instability of the unpreserved urine. Preserved urine exhibited a loss of around 0.5% after 22 days at refrigerated storage conditions of 4 °C.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.012
      Issue No: Vol. 982 (2017)
  • Dried urine spots - A novel sampling technique for comprehensive LC-MSn
           drug screening
    • Authors: Julian A. Michely; Markus R. Meyer; Hans H. Maurer
      Pages: 112 - 121
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Julian A. Michely, Markus R. Meyer, Hans H. Maurer
      Dried matrix spot (DMS) technique as alternative sampling strategy, especially dried urine spots (DUS), might be an alternative for drug screening. So far only particular drugs or drug classes were covered in DMS screenings. Therefore, workup of DUS for a broad comprehensive library-based LC-MSn screening was developed. It consisted of enzymatic on-spot deconjugation followed by liquid extraction and LC-MSn analysis. This workup was compared to established urine precipitation (UP) and validated according to international guidelines for qualitative approaches, using exemplary compounds of several drug classes (antidepressants, benzodiazepines, cardiovascular drugs, neuroleptics, opioids, stimulants, etc.) with a broad range of (physico-)chemical properties and chromatographic behaviors. On-spot conjugate cleavage and liquid extraction was sufficient for most compounds and the validation results comparable to those obtained after simple UP. For demonstrating the applicability, 103 authentic urine samples, six rat urine samples after low dose substance administrations, and two proficiency tests for systematic toxicological urinalysis were worked up with the new DUS approach or by UP without or with conjugate cleavage. In the authentic urine samples, 112 different drugs out of 43 categories plus metabolites were identified via the used LC-MSn library. With the new DUS approach, 5% less positive hits could be found compared to the UP approach and 15% less than the latter after conjugate cleavage. The differences should be caused mainly by smaller urine volumes used for DUS. In the two proficiency tests, all 15 drugs could be detected. Unfortunately, all three approaches were not able to detect very low-dosed substances in rat urine samples. However, they could be detected using a more sensitive LC-high resolution-MS/MS approach showing that the DUS workup was also suitable for those. In conclusion, DUS might be an alternative sampling technique for comprehensive drug testing or adherence monitoring.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.033
      Issue No: Vol. 982 (2017)
  • Capillary electrophoresis-tandem mass spectrometry as a highly selective
           tool for the compositional and site-specific assessment of multiple
    • Authors: Elena Dominguez-Vega; Thomas De Vijlder; Edwin P. Romijn; Govert W. Somsen
      Pages: 122 - 130
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Elena Dominguez-Vega, Thomas De Vijlder, Edwin P. Romijn, Govert W. Somsen
      Site-specific mapping of multiple deamidations in peptides is a challenging analytical task. In this work, capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) is presented as a high-resolution tool for the detailed characterization of these subtle modifications in peptides. The 4.5-kDa peptide drug TRI-1144, which contains five closely-positioned potential deamidation sites, was selected as model compound. TRI-1144 was exposed to acidic conditions and/or elevated temperatures for 1–14 h. Stressed samples were analyzed using a background electrolyte (BGE) of 150 mM ammonium formate (pH 6.0) in combination with a capillary coated with a bilayer of Polybrene-dextran sulfate. Separation of deamidated and deacetylated TRI-1144 species, including several positional isomers, was greatly enhanced by adding up to 40 vol% of acetonitrile-isopropanol (87.5:12.5, v/v) to the BGE, allowing reliable determination of the number of deamidations/deacetylations per degradation product. Collision-induced dissociation MS/MS was conducted on the separated peptide components in order to reveal the exact position of deamidation on the peptide chain. Obtained fragment ions showed overlapping isotopic distributions in their MS/MS spectra resulting from the comigration of different isomeric deamidated species. Comparison of theoretical and measured isotope distributions for specific y ions of peptide fragments yielded the identity and relative abundance of isomeric deamidated products. The developed CE-MS/MS methodology was used for the highly selective evaluation of TRI-1144 stability under different stress conditions, providing detailed qualitative and semi-quantitative degradation maps of the peptide drug.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.021
      Issue No: Vol. 982 (2017)
  • Real-time observation of perturbation of a Drosophila embryo's early
           cleavage cycles with microfluidics
    • Authors: Zeqing Bai; Hongcun Bao; Yingying Yuan; Xiaohang Yang; Yongmei Xi; Min Wang
      Pages: 131 - 137
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Zeqing Bai, Hongcun Bao, Yingying Yuan, Xiaohang Yang, Yongmei Xi, Min Wang
      It is of great importance to understand biochemical system's behavior toward environmental perturbation during the development of living organisms. Here a microfluidic platform for Drosophila embryo's online development and observation is presented. The system is capable of developing the embryo's anterior and posterior halves controlled at different temperature environments, and it can be easily coupled with a confocal microscope for real-time image acquisition. The microfluidic chip is consisted of a polymethylmethacrylate (PMMA) substrate with a thickness of 4.0 mm and a polydimethylsiloxane (PDMS) cover designed with a typical ‘Y’ channel with a depth of 400 μm, width of 800 μm. Temperature gradients were created across the anterior half and posterior half of the embryo by utilizing two streams of laminar flow with different temperatures. It was found that thermal gradient would result in asynchronous development of the two halves of the embryos, and the developing difference was related to the direction of thermal gradient. This may result from the presence of an unknown mechanism located in the anterior half of the embryo, which oversees nuclear division synchronicity. These observations would help better understand compensatory mechanisms of Drosophila embryo's development under environmental perturbations.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.024
      Issue No: Vol. 982 (2017)
  • Streptavidin-biotin-peroxidase nanocomplex-amplified microfluidics
           immunoassays for simultaneous detection of inflammatory biomarkers
    • Authors: Jing Wu; Yiping Chen; Mingzhu Yang; Yu Wang; Cheng Zhang; Mo Yang; Jiashu Sun; Mengxia Xie; Xingyu Jiang
      Pages: 138 - 147
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Jing Wu, Yiping Chen, Mingzhu Yang, Yu Wang, Cheng Zhang, Mo Yang, Jiashu Sun, Mengxia Xie, Xingyu Jiang
      Simultaneous, sensitive and quantitative detection of biomarkers in infectious disease is crucial for guiding antimicrobial treatment and predicting prognosis. This work reported an ultrasensitive and quantitative microfluidic immunoassay combined with the streptavidin-biotin-peroxidase (SA-B-HRP) nanocomplex-signal amplification system (MIS) to detect two inflammatory biomarkers, procalcitonin (PCT, for discriminating bacterial infections from nonbacterial infections) and interleukin-6 (IL-6, for monitoring the kinetics of infectious disease) simultaneously. The amplification system was based on the one step self-assembly of SA and B-HRP to form the SA-B-HRP nanocomplex, which effectively amplified the chemiluminescent signals. The linear ranges for PCT and IL-6 detections by MIS were 250–1.28 × 105 pg mL−1 and 5–1280 pg mL−1, and the limit of detection (LOD) were 48.9 pg mL−1 and 1.0 pg mL−1, respectively, both of which were significantly improved compared with microfluidic immunoassays without amplification system (MI). More importantly, PCT and IL-6 in human serum could be simultaneously detected in the same run by MIS, which could greatly improve the detection efficiency and reduce the cost. Given the advantages of high sensitivity, multiplex and quantitative detection, MIS could be potentially applied for detection of biomarkers at low concentration in clinical diagnosis.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.031
      Issue No: Vol. 982 (2017)
  • Determination of aqueous antibiotic solutions using SERS nanogratings
    • Authors: Koh Yiin Hong; Carlos Diego Lima de Albuquerque; Ronei J. Poppi; Alexandre G. Brolo
      Pages: 148 - 155
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Koh Yiin Hong, Carlos Diego Lima de Albuquerque, Ronei J. Poppi, Alexandre G. Brolo
      The emergence of antibiotics and their active metabolites in aquatic ecosystem has motivated the development of sensitive and reliable sensors to monitor traces of antibiotics and metabolites in drinking water sources (i.e. surface water). The surface enhanced Raman scattering (SERS) technique, which is widely recognized as a high sensitivity method for molecular vibrational detection, is potentially a powerful tool for trace environmental contamination analysis. The main goal of this work is to demonstrate pharmaceutical and metabolite multiplexing detection using the SERS approach. Periodic metallic nanostructures were fabricated using laser interference lithography (LIL) and used as SERS substrates (platform that supports the SERS effect). The LIL method allowed excellent substrate-to-substrate geometric parameters variations; for instance, the variations in periodicity were determined to be less than 1%. A common fluoroquinolone (FQ) parent-and-metabolite pair, enrofloxacin (ENRO) and ciprofloxacin (CIPRO), was targeted for multiplexing detection on the relative uniform substrates fabricated by LIL. The quantifications of the analytes mixtures were achieved by chemometric analysis (i.e. non-negative matrix factorization with alternating least square algorithm (NMF-ALS)). The limit of the quantification (LOQ) of the present method is in the ppm-level with less than 10% spatial variation in the SERS signal.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.025
      Issue No: Vol. 982 (2017)
  • Highly sensitive strategy for identification of trace chemicals in complex
           matrix: Application to analysis of monacolin analogues in
           monascus-fermented rice product
    • Authors: Meng-Ning Li; Chao-Ran Li; Wen Gao; Ping Li; Hua Yang
      Pages: 156 - 167
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Meng-Ning Li, Chao-Ran Li, Wen Gao, Ping Li, Hua Yang
      Trace analysis of chemical analogues was always a hot topic and attracted the researchers' attentions. In this study, a database/multi-step filtering strategy was developed by using HPLC-Chip-MS system for comprehensive characterization of monacolin analogues in monascus-fermented rice product (MFRP). This strategy mainly included three steps, including chemical profile of MFRP by HPLC-Chip-MS, establishment of monacolin analogue database, multi-step filtering of monacolins based on modified mass defect filtering. All target compounds showed the symmetrical peak shapes and high MS response by using nanoflow HPLC-Chip-MS. According to the previous literature and experimental MS data, a database including 720 monacolin analogues was established. The original 522 ions in MFRP were automatically extracted by molecular feature extraction function. And then, through rectangular mass defect filtering and analogues distribution area filtering, 298 ions were further excluded. Finally, a total of 84 monacolins including 16 new compounds were unambiguously identified or tentatively characterized based on MS/MS information. In comparison with conventional mass defect filtering method, the proposed method was accurately able to exclude false positive results. The 438 false positive results were excluded in our study, while only 250 ones would be filtered out by using conventional method. This study provided a sensitive and powerful method for rapidly characterization of trace chemicals in complex matrix.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.05.030
      Issue No: Vol. 982 (2017)
  • Palladium-copper nanowires-based biosensor for the ultrasensitive
           detection of organophosphate pesticides
    • Authors: Dandan Song; Yan Li; Xiong Lu; Muxue Sun; Hui Liu; Guangming Yu; Faming Gao
      Pages: 168 - 175
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Dandan Song, Yan Li, Xiong Lu, Muxue Sun, Hui Liu, Guangming Yu, Faming Gao
      A highly sensitive acetylcholinesterase (AChE) electrochemical biosensor for the quantitative determination of organophosphate pesticides (OPs) in vegetables and fruits based on palladium-copper nanowires (Pd-Cu NWs) was reported. AChE immobilized on the modified electrode could catalyze hydrolysis of acetylthiocholine chloride (ATCl), generating an irreversible oxidation peak. When exposed to the OPs, the activity of the AChE was inhibited and the current significantly decreased. The detection mechanism is based on the inhibition of AChE. The Pd-Cu NWs not only provide a large active surface area (0.268 ± 0.01) cm2 for the immobilization of AChE, which was approximately 3.8 times higher than the bare glass carbon electrode, but also exhibit excellent electro-catalytic activity and remarkable electron mobility. The biosensor modified with Pd-Cu NWs displayed a good affinity to ATCl and catalyzed hydrolysis of ATCl, with a low Michaelis–Menten constant (K M ) of 50.56 μM. Under optimized conditions, the AChE-Cs/Pd-Cu NWs/GCE biosensor detected malathion with wide linear ranges of 5–1000 ppt and 500–3000 ppb, and the low detection limit was 1.5 ppt (4.5 pM). In addition, the OPs biosensor has been applied to the analysis of malathion in commercial vegetable and fruit samples, with excellent recoveries in the range of 98.5%–113.5%. This work provides a simple, sensitive and effective platform for biosensors and exhibits future potential in practical application for the OPs assay.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.004
      Issue No: Vol. 982 (2017)
  • YSZ-based sensor using Cr-Fe-based spinel-oxide electrodes for selective
           detection of CO
    • Authors: Sri Ayu Anggraini; Yuki Fujio; Hiroshi Ikeda; Norio Miura
      Pages: 176 - 184
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Sri Ayu Anggraini, Yuki Fujio, Hiroshi Ikeda, Norio Miura
      A selective carbon monoxide (CO) sensor was developed by the use of both of CuCrFeO4 and CoCrFeO4 as the sensing electrode (SE) for yttria-stabilized zirconia (YSZ)-based potentiometric sensor. The sensing-characteristic examinations of the YSZ-based sensors using each of spinel oxides as the single-SE sensor showed that CuCrFeO4-SE had the ability to detect CO, hydrocarbons and NOx gases, while CoCrFeO4-SE was sensitive to hydrocarbons and NOx gases. Thus, when both SEs were paired as a combined-SEs sensor, the resulting sensor could generate a selective response to CO at 450 °C under humid conditions. The sensor was also capable of detecting CO in the concentration range of 20–700 ppm. Its sensing mechanism that was examined via polarization-curve measurements was confirmed to be based on mixed-potential model. The CO response generated by the combined-SEs sensor was unaffected by the change of water vapor concentration in the range of 1.3–11.5 vol% H2O. Additionally, the sensing performance was stable during 13 days tested.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.010
      Issue No: Vol. 982 (2017)
  • Fluorescent quenching immune chromatographic strips with quantum dots and
           upconversion nanoparticles as fluorescent donors for visual detection of
           sulfaquinoxaline in foods of animal origin
    • Authors: Gaoshuang Hu; Wei Sheng; Jingmin Li; Yan Zhang; Junping Wang; Shuo Wang
      Pages: 185 - 192
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Gaoshuang Hu, Wei Sheng, Jingmin Li, Yan Zhang, Junping Wang, Shuo Wang
      In this study, two novel fluorescence quenching immune chromatographic strips (FQICS) were developed to detect sulfaquinoxaline (SQX) in foods of animal origin. These proposed FQICSs were based on fluorescence resonance energy transfer (FRET) from fluorescence donors (quantum dots or upconversion nanoparticles) to fluorescence acceptors (colloidal gold nanoparticles). Compared with traditional colloidal gold-based immune chromatographic strips (ICS), these FQICSs showed positive correlation between the fluorescent signals and the targets, and allowed user to get test results from weak fluorescent signals. The visual detection limits of these two FQICSs were both 1 ng mL−1 in standard solution and 8 μg kg−1 in samples, while the visual detection limit of the colloidal gold-based ICS was 10 ng mL−1 in standard solution and 80 μg kg−1 in samples. Besides, the results we obtained by the use of FQICS showed high agreement with those obtained by the use of commercial ELISA kits, indicating the good accuracy of these strips. As a conclusion, these proposed FQICS based on quantum dots and upconversion nanoparticles can be applied in sensitive, rapid and on-site detection of SQX in foods of animal origin.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.013
      Issue No: Vol. 982 (2017)
  • Fast multiplex analysis of antibodies in complex sample matrix using the
           microfluidic Evalution™ platform
    • Authors: Karen Leirs; Pelin Leblebici; Jeroen Lammertyn; Dragana Spasic
      Pages: 193 - 199
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Karen Leirs, Pelin Leblebici, Jeroen Lammertyn, Dragana Spasic
      Biosensor development requires comprehensive research for establishing the optimal bioassay conditions that determine the final kinetics, sensitivity and specificity. Different systems have been developed to study bioreceptor-target interactions but they often have drawbacks, such as long hands-on time, low throughput, high sample consumption and high cost. In this work, the potential of the novel microfluidic Evalution™ platform has been evaluated for developing sandwich-based assays in a fast and high-throughput fashion. An immunoassay for the detection of influenza A nucleoprotein was used as a model system. Exploiting the platform's unique features, various typical bioassay parameters (e.g. aspecific binding between assay components, different reagent concentrations and incubation times) were tested for three capture antibodies in a simple and fast manner (2 runs of 80 min). The selected conditions, giving the highest signal-to-noise ratio, were directly employed on the same platform to detect nucleoprotein in buffer and nasopharyngeal swabs. Two antibodies with a higher dissociation constant (Ab11 and Ab12) required longer incubation times (60 min) for sensitive detection (limit of detection (LOD) of 0.48 and 0.26 ng mL−1, respectively) compared to an antibody with lower dissociation constant (LOD of 0.04 ng mL−1 for Ab66 within 30 min). Moreover, one antibody (Ab12) showed limited capacity to capture nucleoprotein directly in sample matrix. The obtained results were in accordance with previous studies performed on an ELISA and SPR platform with the same antibodies. This positions the Evalution™ platform as a reliable platform for fast and multiplex analysis of antibodies' performance both in buffer and complex sample matrices.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.018
      Issue No: Vol. 982 (2017)
  • Preparation of intact mitochondria using free-flow isoelectric focusing
           with post-pH gradient sample injection for morphological, functional and
           proteomics studies
    • Authors: Yu-Chen He; Fan-Zhi Kong; Liu-Yin Fan; Jane Y. Wu; Xiao-Ping Liu; Jun Li; Yan Sun; Qiang Zhang; Ying Yang; Xue-Jing Wu; Hua Xiao; Cheng-Xi Cao
      Pages: 200 - 208
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Yu-Chen He, Fan-Zhi Kong, Liu-Yin Fan, Jane Y. Wu, Xiao-Ping Liu, Jun Li, Yan Sun, Qiang Zhang, Ying Yang, Xue-Jing Wu, Hua Xiao, Cheng-Xi Cao
      Mitochondria play essential roles in both energy metabolism and cell signaling, which are critical for cell survival. Although significant efforts have been invested in understanding mitochondrial biology, methods for intact mitochondria preparation are technically challenging and remain to be improved. New methods for heterogeneous mitochondria purification will therefore boost our understanding on their physiological and biophysical properties. Herein, we developed a novel recycling free-flow isoelectric focusing (RFFIEF) with post-pH gradient sample injection (post-PGSI) for preparative separation of mitochondria. Crude mitochondria of rabbit liver obtained from differential centrifugation were purified by the developed method according to their pI values as six fractions. Transmission electron microscope images revealed that intact mitochondria existed in two fractions of pH 6.24 and 6.61, degenerative mitochondria were in two fractions of pH 5.46 and 5.72, and inner membrane vesicles (IMVs) appeared in the fractions of pH 4.70 and 5.04. Membrane potential measurement proved a dramatic difference between intact mitochondria and IMVs, which reflected the bioactivity of obtained populations. Particularly, proteomics analyses revealed that more number of proteins were identified in the intact fractions than that of IMVs or crude mitochondria, which demonstrated that RFFIEF could be powerful tool for the preparation of intact organelle as well as their proteomic and in-depth biological analysis.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.007
      Issue No: Vol. 982 (2017)
  • Discrimination of bacteria by rapid sensing their metabolic volatiles
           using an aspiration-type ion mobility spectrometer (a-IMS) and gas
           chromatography-mass spectrometry GC-MS
    • Authors: Ileana Andreea Ratiu; Victor Bocos-Bintintan; Adrian Patrut; Victor Hugo Moll; Matthew Turner; C.L. Paul Thomas
      Pages: 209 - 217
      Abstract: Publication date: 22 August 2017
      Source:Analytica Chimica Acta, Volume 982
      Author(s): Ileana Andreea Ratiu, Victor Bocos-Bintintan, Adrian Patrut, Victor Hugo Moll, Matthew Turner, C.L. Paul Thomas
      The objective of our study was to investigate whether one may quickly and reliably discriminate different microorganism strains by direct monitoring of the headspace atmosphere above their cultures. Headspace samples above a series of in vitro bacterial cultures were directly interrogated using an aspiration type ion mobility spectrometer (a-IMS), which produced distinct profiles (“fingerprints”) of ion currents generated simultaneously by the detectors present inside the ion mobility cell. Data processing and analysis using principal component analysis showed net differences in the responses produced by volatiles emitted by various bacterial strains. Fingerprint assignments were conferred on the basis of product ion mobilities; ions of differing size and mass were deflected in a different degree upon their introduction of a transverse electric field, impacting finally on a series of capacitors (denominated as detectors, or channels) placed in a manner analogous to sensor arrays. Three microorganism strains were investigated – Escherichia coli, Bacillus subtilis and Staphylococcus aureus; all strains possess a relatively low pathogenic character. Samples of air with a 5 cm3 volume from the headspace above the bacterial cultures in agar growth medium were collected using a gas-tight chromatographic syringe and injected inside the closed-loop pneumatic circuit of the breadboard a-IMS instrument model ChemPro-100i (Environics Oy, Finland), at a distance of about 1 cm from the ionization source. The resulting chemical fingerprints were produced within two seconds from the moment of injection. The sampling protocol involved to taking three replicate samples from each of 10 different cultures for a specific strain, during a total period of 72 h after the initial incubation – at 24, 48 and 72 h, respectively. Principal component analysis (PCA) was used to discriminate between the IMS fingerprints. PCA was found to successfully discriminate between bacteria at three levels in the experimental campaign: 1) between blank samples from growth medium and samples from bacterial cultures, 2) between samples from different bacterial strains, and 3) between time evolutions of headspace samples from the same bacterial strain over the 3-day sampling period. Consistent classification between growth medium samples and growth medium inoculated with bacteria was observed in both positive and negative detection/ionization modes. In parallel, headspace air samples of 1 dm3 were collected from each bacterial culture and loaded onto Tenax™-Carbograph desorption tubes, using a custom built sampling unit based on a portable sampling pump. One sample was taken for each of 10 different cultures of a strain, at 24, 48 and 72 h after the initial incubation. These adsorption tubes were subsequently analyzed using thermal desorption – gas chromatography – mass spectrometry (TD-GC-MS). This second dataset was intended to produce a qualitative analysis of the volatiles present in the headspace above the bacterial cultures.
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      PubDate: 2017-07-21T11:16:48Z
      DOI: 10.1016/j.aca.2017.06.031
      Issue No: Vol. 982 (2017)
  • Determination of formylated DNA and RNA by chemical labeling combined with
           mass spectrometry analysis
    • Authors: Han-Peng Jiang; Ting Liu; Ning Guo; Lei Yu; Bi-Feng Yuan; Yu-Qi Feng
      Pages: 1 - 10
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Han-Peng Jiang, Ting Liu, Ning Guo, Lei Yu, Bi-Feng Yuan, Yu-Qi Feng
      Nucleic acids carry diverse chemical modifications that exert critical influences in a variety of cellular processes in living organisms. In addition to methylation, the emerging DNA and RNA formylation has been reported to play functional roles in various physiological processes. However, the amounts of formylated DNA and RNA are extremely low and detection of DNA and RNA formylation is therefore a challenging task. To address this issue, we developed a strategy by chemical labeling combined with in-tube solid-phase microextraction - ultra high performance liquid chromatography - electrospray ionization - tandem mass spectrometry (in-tube SPME-UPLC-ESI-MS/MS) analysis for the sensitive determination of DNA and RNA formylation. Using the developed method, we were able to simultaneously measure six formylated nucleosides, including 5-formyl-2′-deoxycytidine (5-fodC), 5-formylcytidine (5-forC), 5-formyl-2′-deoxyuridine (5-fodU), 5-formyluridine (5-forU), 2′-O-methyl-5-formylcytidine (5-forCm) and 2′-O-methyl-5- formyluridine (5-forUm), from DNA and RNA of cultured human cells and multiple mammalian tissues. The detection limits of these formylated nucleosides improved by 307–884 folds using Girard's P (GirP) labeling coupled with in-tube SPME-UPLC-ESI-MS/MS analysis. It was worth noting that 5-forU, 5-forCm and 5-forUm which have not been detected in human sample before, were discovered in cultured human cells and tissues in the current study. In addition, we observed significant increase of 5-forC and 5-forU in RNA (p = 0.027 for 5-forC; p = 0.028 for 5-forU) and 5-fodU in DNA (p = 0.002) in human thyroid carcinoma tissues compared to normal tissues adjacent to the tumor using synthesized stable isotope GirP (d 5-GirP)-assisted quantification. Our results indicated that aberrant DNA and RNA formylation may contribute to the tumor formation and development. In addition, monitoring of DNA and RNA formylation may also serve as indicator for cancer diagnostics. Taken together, the developed chemical labeling combined with in-tube SPME-UPLC-ESI-MS/MS analysis can facilitate the in-depth functional study of DNA and RNA formylation.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.06.009
      Issue No: Vol. 981 (2017)
  • Impact of γ-irradiation, ageing and their interactions on multilayer
           films followed by AComDim
    • Authors: Fanny Gaston; Nathalie Dupuy; Sylvain R.A. Marque; Magali Barbaroux; Samuel Dorey
      Pages: 11 - 23
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Fanny Gaston, Nathalie Dupuy, Sylvain R.A. Marque, Magali Barbaroux, Samuel Dorey
      To highlight the main factors involved in the degradation of polymers in multilayer films under γ-irradiation, the ANOVA Common Dimensions (AComDim, Analysis of Variance in Common Dimensions) method is applied on spectra recorded with ATR-FTIR (Attenuated Total Reflection-Fourier Transform Infrared). The present study focuses on the stability of γ-irradiated polymers used in single-use plastic bags made of multilayer films for the biopharmaceutical and biotechnological industries. The samples are irradiated at several γ-doses, up to 270 kGy, and compared with a non-irradiated sample used as reference. It shows that the γ-dose, the natural ageing up to six months and the γ-dose × ageing interaction are the most influential factors.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.021
      Issue No: Vol. 981 (2017)
  • Point-of-need simultaneous electrochemical detection of lead and cadmium
           using low-cost stencil-printed transparency electrodes
    • Authors: Daniel Martín-Yerga; Isabel Álvarez-Martos; M. Carmen Blanco-López; Charles S. Henry; M. Teresa Fernández-Abedul
      Pages: 24 - 33
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Daniel Martín-Yerga, Isabel Álvarez-Martos, M. Carmen Blanco-López, Charles S. Henry, M. Teresa Fernández-Abedul
      In this work, we report a simple and yet efficient stencil-printed electrochemical platform that can be integrated into the caps of sample containers and thus, allows in-field quantification of Cd(II) and Pb(II) in river water samples. The device exploits the low-cost features of carbon (as electrode material) and paper/polyester transparency sheets (as substrate). Electrochemical analysis of the working electrodes prepared on different substrates (polyester transparency sheets, chromatographic, tracing and office papers) with hexaammineruthenium(III) showed that their electroactive area and electron transfer kinetics are highly affected by the porosity of the material. Electrodes prepared on transparency substrates showed the best electroanalytical performance for the simultaneous determination of Cd(II) and Pb(II) by square-wave anodic stripping voltammetry. Interestingly, the temperature and time at which the carbon ink was cured had significant effect on the electrochemical response, especially the capacitive current. The amount of Cd and Pb on the electrode surface can be increased about 20% by in situ electrodeposition of bismuth. The electrochemical platform showed a linear range comprised between 1 and 200 μg/L for both metals, sensitivity of analysis of 0.22 and 0.087 μA/ppb and limits of detection of 0.2 and 0.3 μg/L for Cd(II) and Pb(II), respectively. The analysis of river water samples was done directly in the container where the sample was collected, which simplifies the procedure and approaches field analysis. The developed point-of-need detection system allowed simultaneous determination of Cd(II) and Pb(II) in those samples using the standard addition method with precise and accurate results.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.027
      Issue No: Vol. 981 (2017)
  • One-step synthesis of functional pNR/rGO composite as a building block for
           enhanced ascorbic acid biosensing
    • Authors: Ling Liu; Junfeng Zhai; Chengzhou Zhu; Lei Han; Wen Ren; Shaojun Dong
      Pages: 34 - 40
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Ling Liu, Junfeng Zhai, Chengzhou Zhu, Lei Han, Wen Ren, Shaojun Dong
      An electrochemical sensor for ascorbic acid (AA) was prepared via an one-step electrochemical approach by reducing graphene oxide (rGO) and co-polymerizing neutral red (NR) and rGO to form a pNR/rGO hybrid film on the glassy carbon electrode (pNR/rGO-GCE). Structures and properties of the obtained pNR/rGO film were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) and UV-vis techniques. A significant decrease of charge-transfer resistance (Rct) from over 20,000 Ω for pNR-GCE to 130 Ω for pNR/rGO-GCE was validated by electrochemical impedance spectroscopy (EIS) measurement. Particularly, electrochemical data revealed that pNR/rGO film could effectively enhance the electron transfer between AA and electrode, and thus reduce the overpotential of AA oxidation. Two linear regression areas with 0.05–0.75 mM and 0.9–24.9 mM, detection limit with 1.4 μM, and stability over 2 weeks were obtained. The coexisting distractions such as dopamine, uric acid and glucose were detected and eliminated. Moreover, the pNR/rGO-GCE gave the same determination results as that obtained with HPLC when measuring real samples, including vitamin C beverage and human serum.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.023
      Issue No: Vol. 981 (2017)
  • Electrochemical detection of cardiac biomarker myoglobin using polyphenol
           as imprinted polymer receptor
    • Authors: J.A. Ribeiro; C.M. Pereira; A.F. Silva; M. Goreti F. Sales
      Pages: 41 - 52
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): J.A. Ribeiro, C.M. Pereira, A.F. Silva, M. Goreti F. Sales
      An electrochemical biosensor was developed by merging the features of Molecular Imprinting technique and Screen-Printed Electrode (SPE) for the simple and fast screening of cardiac biomarker myoglobin (Myo) in point-of-care (POC). The MIP artificial receptor for Myo was prepared by electrooxidative polymerization of phenol (Ph) on a AuSPE in the presence of Myo as template molecule. The choice of the most effective protein extraction procedure from the various extraction methods tested (mildly acidic/basic solutions, pure/mixed organic solvents, solutions containing surfactants and enzymatic digestion methods), and the optimization of the thickness of the polymer film was carefully undertaken in order to improve binding characteristics of Myo to the imprinted polymer receptor and increase the sensitivity of the MIP biosensor. The film thickness was optimized by adjusting scan rate and the number of cycles during cyclic voltammetric electropolymerization of Ph. The thickness of the polyphenol nanocoating of only few nanometres (∼4.4 nm), and similar to the protein diameter, brought in significant improvements in terms of sensor sensitivity. The binding affinity of MIP receptor film was estimated by fitting the experimental data to Freundlich isotherm and a ∼8 fold increase in the binding affinity of Myo to the imprinted polymer (KF = 0.119 ± 0.002 ng−1 mL) when compared to the non-imprinted polymer (KF = 0.015 ± 0.002 ng−1 mL) which demonstrated excellent (re)binding affinity for the imprinted protein. The incubation of the Myo MIP receptor modified electrode with increasing concentration of protein (from 0.001 ng mL−1 to 100 μg mL−1) resulted in a decrease of the ferro/ferricyanide redox current. LODs of 2.1 and 14 pg mL−1 were obtained from calibration curves built in neutral buffer and diluted artificial serum, respectively, using SWV technique, enabling the detection of the protein biomarker at clinically relevant levels. The prepared MIP biosensor was applied to the determination of Myo spiked serum samples with satisfactory results.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.017
      Issue No: Vol. 981 (2017)
  • Sialic acid linkage-specific permethylation for improved profiling of
           protein glycosylation by MALDI-TOF MS
    • Authors: Kuan Jiang; He Zhu; Lei Li; Yuxi Guo; Ebtesam Gashash; Cheng Ma; Xiaolin Sun; Jing Li; Lianwen Zhang; Peng George Wang
      Pages: 53 - 61
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Kuan Jiang, He Zhu, Lei Li, Yuxi Guo, Ebtesam Gashash, Cheng Ma, Xiaolin Sun, Jing Li, Lianwen Zhang, Peng George Wang
      Protein glycosylation mediates a wide range of cellular processes, affecting development and disease in mammals. Deciphering the “glycocodes” requires rapid, sensitive and in-depth characterization of diverse glycan structures derived from biological samples. In this study, we described a two-step derivatization strategy termed linkage-specific sialic acid permethylation (SSAP) consisting of dimethylamination and permethylation for the improved profiling of glycosylation by matrix-assisted laser desorption/ionization (MALDI) time-of-fight (TOF) mass spectrometry (MS). High linkage-specificity (∼99%) of SSAP to both the two most common forms of sialic acid, N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), permitted direct discrimination of α2,3- and α2,6-linked sialic acids in MALDI-TOF MS. The enhanced intensity (>10-fold) and increased detection limit (>10-fold) of derivatized glycans were valued for sensitive glycomics. Moreover, the good compatibility and reaction efficiency of the two steps of SSAP allowed rapid sample preparation (<2 h), benefiting robust analysis of glycans in a high-throughput manner. The SSAP strategy was further applied to investigate the protein glycosylation of human serum associated with rheumatoid arthritis (RA). It was demonstrated that the relative abundances of individual glycans were different in RA negative and RA positive samples, and meanwhile the RA patient/control ratios of both α2,3- and α2,6-sialylated glycans tended to elevate accompanied with the increase of sialylation. Those findings of the glycosylation changes occurred in human serum protein may contribute to the diagnosis of RA. Herein, SSAP derivatization combined with MALDI-TOF MS exhibits unique advantages for glycomic analysis and shows potential in glycosylation profiling of therapeutic proteins and clinical glycan biomarker discovery.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.029
      Issue No: Vol. 981 (2017)
  • Chiral differentiation of amino acids through binuclear copper bound
           tetramers by ion mobility mass spectrometry
    • Authors: Xiangying Yu; Zhong-Ping Yao
      Pages: 62 - 70
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Xiangying Yu, Zhong-Ping Yao
      In this study, travelling wave ion mobility mass spectrometry has been used to investigate chiral differentiation of common chiral amino acids, through separation of binuclear copper bound tetrameric ions formed with chiral selector tryptophan, proline, tyrosine, phenylalanine or histidine. Significant chiral recognition was observed for amino acids with aromatic rings or long and active side chains, with peak-to-peak resolutions up to 1.826. Tryptophan and histidine offered better enantioselectivity, compared to other chiral selectors. The results suggested that the mechanism for chiral recognition in ion mobility mass spectrometry might be significantly different from that in tandem mass spectrometry. Linear calibration curves were also established to allow determination of enantiomeric excess of the analytes by the approach. This study showed that higher assembly of chiral analyte and chiral selector might enable better chiral discrimination and ion mobility mass spectrometry could be a powerful technique for provide qualitative, quantitative and structural information of chiral analysis.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.026
      Issue No: Vol. 981 (2017)
  • Simple area determination of strongly overlapping ion mobility peaks
    • Authors: Lucie Borovcová; Martina Hermannová; Volodymyr Pauk; Matěj Šimek; Vladimír Havlíček; Karel Lemr
      Pages: 71 - 79
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Lucie Borovcová, Martina Hermannová, Volodymyr Pauk, Matěj Šimek, Vladimír Havlíček, Karel Lemr
      Coupling of ion mobility with mass spectrometry has brought new frontiers in separation and quantitation of a wide range of isobaric/isomeric compounds. Ion mobility spectrometry may separate ions possessing the identical molecular formula but having different molecular shapes. The separation space in most commercially available instruments is limited and rarely the mobility resolving power exceeds one hundred. From this perspective, new approaches allowing for extracting individual compound signals out of a more complex mixture are needed. In this work we present a new simple analytical approach based on fitting of arrival time distribution (ATD) profiles by Gaussian functions and generating of ATD functions. These ATD functions well describe even distorted ion mobility peaks of individual compounds and allow for extracting their peaks from mobilograms of mixtures. Contrary to classical integration, our approach works well with irregular overlapping peaks. Using mobilograms of standards to generate ATD functions, poorly separated compounds, e.g. isomers, with identical mass spectra representing a hard to solve task for various chemometric methods can be easily distinguished by our procedure. Alternatively ATD functions can be obtained from ATD profiles of ions unique to individual mixture components (if such ions exist) and mobilograms of standards are not required. On a set of hyaluronan-derived oligosaccharides we demonstrated excellent ATD repeatability enabling the resolution of binary mixtures, including mixtures with minor component level about 5%. Ion mobility quantitative data of isomers were confirmed by high performance liquid chromatography.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.003
      Issue No: Vol. 981 (2017)
  • Wheat germ agglutinin and Lens culinaris agglutinin sensitized anisotropic
    • Authors: Mariam V. Mikaelyan; Gayane G. Poghosyan; Olga D. Hendrickson; Boris B. Dzantiev; Vardan K. Gasparyan
      Pages: 80 - 85
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Mariam V. Mikaelyan, Gayane G. Poghosyan, Olga D. Hendrickson, Boris B. Dzantiev, Vardan K. Gasparyan
      Efficacy of anisotropic silver nanoparticles sensitized with wheat germ agglutinin (WGA) and Lens culinaris agglutinin (LCA) was studied for detection of Staphylococcus aureus and Escherichia coli. It was demonstrated that interaction of these nanoparticles with bacteria stabilizes them and prevents their aggregation upon addition of sodium chloride; such stabilization depends on bacteria concentration. High concentration of bacteria results in higher stabilization whereas low concentration leads to aggregation of nanoparticles. Optical changes as a result of aggregation correlate with bacteria concentration. The developed approach allows the detection of Gram-positive bacteria (S.aureus) with the lowest detectable concentration of 103 cells/mL and Gram-negative bacteria (E. coli) with the lowest detectable concentration of 3 × 103 cells/mL using WGA-sensitized nanoparticles. In the case of LCA-sensitized nanoparticles the lowest detection was 5 × 103 cells/mL for S. aureus and 5 × 104 cells/mL for E. coli.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.022
      Issue No: Vol. 981 (2017)
  • A fluorescent dyad with large emission shift for discrimination of
           cysteine/homocysteine from glutathione and hydrogen sulfide and the
           application of bioimaging
    • Authors: Xueling Yang; Longwei He; Kaixin Xu; Weiying Lin
      Pages: 86 - 93
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Xueling Yang, Longwei He, Kaixin Xu, Weiying Lin
      Biothiols, as reactive sulfur species (RSS), play important roles in human physiology, and they have a close connection of generation and metabolism pathways among of them. It is challenging to discriminate biothiols from each other due to the similar chemical structures and properties of them. Herein, we develop a fluorescent hybrid dyad (CS-NBD) for efficiently discriminating cysteine (Cys)/homocysteine (Hcy) from glutathione (GSH) and hydrogen sulfide (H2S) by a dual-channel detection method. CS-NBD performs inherently no fluorescence in ranging from visible to near infrared region. However, upon addition of Cys (2–150 μM)/Hcy (2–200 μM), CS-NBD generates significant fluorescence enhancement in two distinct emission bands (Green-Red), while encounter of GSH (2–100 μM) or H2S (2–70 μM) induces the fluorescence increase only in the red channel. The detection limit was determined to be 0.021 μM for Cys, 0.037 μM for Hcy, 0.028 μM for GSH, and 0.015 μM for H2S, respectively (S/N = 3). The interval distance between two emission bands is up to 163 nm, which is favourable to acquire the accurate data in measurement due to the reducing of crosstalk signals. CS-NBD is also successfully applied to distinguish Cys/Hcy in cellular context by dual-color fluorescence imaging.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.016
      Issue No: Vol. 981 (2017)
  • Hydrophilic interaction liquid chromatography-mass spectrometry as a new
           tool for the characterization of intact semi-synthetic glycoproteins
    • Authors: Sara Tengattini; Elena Domínguez-Vega; Caterina Temporini; Teodora Bavaro; Francesca Rinaldi; Luciano Piubelli; Loredano Pollegioni; Gabriella Massolini; Govert W. Somsen
      Pages: 94 - 105
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Sara Tengattini, Elena Domínguez-Vega, Caterina Temporini, Teodora Bavaro, Francesca Rinaldi, Luciano Piubelli, Loredano Pollegioni, Gabriella Massolini, Govert W. Somsen
      Improved methods for detailed characterization of complex glycoproteins are required in the growing sector of biopharmaceuticals. Hydrophilic interaction liquid chromatography (HILIC) coupled to high resolution (HR) time-of-flight mass spectrometric (TOF-MS) detection was examined for the characterization of intact neo-glycoproteins prepared by chemical conjugation of synthetic saccharides to the lysine residues of selected recombinant proteins. The separation performances of three different amide HILIC columns (TSKgel Amide-80, XBridge BEH and AdvanceBio Glycan Mapping) were tested. Water-acetonitrile gradients and volatile eluent additives have been explored. Addition of 0.05% (v/v) trifluoroacetic acid to the mobile phase appeared to be essential for achieving optimum resolution of intact glycoforms and minimal ion suppression effects. Gradient elution conditions were optimized for each protein on every column. HILIC stationary phases were evaluated for the analysis of highly heterogeneous semi-synthetic derivatives of the same protein (ribonuclease A), and in the enhanced characterization of TB10.4 and Ag85B glycoconjugates, selected antigens from Mycobacterium tuberculosis (MTB). HILIC-MS results indicated that the HILIC selectivity is predominantly governed by size of the conjugated glycans and number of glycans attached, providing efficient glycoform separation. Moreover, HILIC separation prior to HRMS detection allowed assignment of several product impurities. Additional top-down MS/MS experiments confirmed conjugation at the N-terminus of TB10.4 next to its lysine residue. Overall, the obtained results demonstrate that amide-stationary-phase based HILIC coupled to MS is highly useful for the characterization of intact neo-glycoproteins allowing assessment of the number, identity and relative abundance of glycoforms present in the semi-synthetic products.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.020
      Issue No: Vol. 981 (2017)
  • Direct coupling of supercritical fluid chromatography with tandem mass
           spectrometry for the analysis of amino acids and related compounds:
           Comparing electrospray ionization and atmospheric pressure chemical
    • Authors: Denise Wolrab; Peter Frühauf; Christopher Gerner
      Pages: 106 - 115
      Abstract: Publication date: 15 August 2017
      Source:Analytica Chimica Acta, Volume 981
      Author(s): Denise Wolrab, Peter Frühauf, Christopher Gerner
      For acceptance of supercritical fluid chromatography (SFC) as a routine analysis method, the hyphenation to mass spectrometry (MS), which is typically achieved either by a splitting device or by the employment of an additional make up flow, has to be improved. Direct coupling of SFC to MS (/MS) would simplify the handling of this method. Consequently, this work focused on the direct coupling of SFC to mass spectrometry and the influence of the employed ion source on signal intensities of polar and ionic compounds in biological samples. A method for separating metabolites of the tryptophan pathway as well as other amino acids is shown. Results demonstrate that SFC is capable of separating analytes of polar and ionic nature. Modifications of the SFC system by cryostat cooling lead to higher temperature stability in the booster pump and therefore to a better reproducibility of retention times and a low dispersion nozzle inside the active back pressure regulator (ABPR) significantly improves peak shape and sensitivity when using the MS. The comparison of the ionization efficiencies using electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) in positive and negative ion mode shows analyte depending sensitivities. However, results indicate that APCI is better suitable for the ionization of amino acids with polar side chains, whereas ESI proved superior for the ionization of amino acids featuring hydrophobic residues. Analyte signals were suppressed with ESI when using a complex matrix such as human serum, but rather enhanced when using APCI.
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      PubDate: 2017-07-07T19:49:50Z
      DOI: 10.1016/j.aca.2017.05.005
      Issue No: Vol. 981 (2017)
  • Quantitative NMR analysis of intra- and extracellular metabolism of
           mammalian cells: A tutorial
    • Authors: Sarantos Kostidis; Ruben D. Addie; Hans Morreau; Oleg A. Mayboroda; Martin Giera
      Pages: 1 - 24
      Abstract: Publication date: 8 August 2017
      Source:Analytica Chimica Acta, Volume 980
      Author(s): Sarantos Kostidis, Ruben D. Addie, Hans Morreau, Oleg A. Mayboroda, Martin Giera
      Metabolomics analysis of body fluids as well as cells is depended on many factors. While several well-accepted standard operating procedures for the analysis of body fluids are available, the NMR based quantitative analysis of cellular metabolites is less well standardized. Experimental designs depend on the cell type, the quenching protocol and the applied post-acquisition workflow. Here, we provide a tutorial for the quantitative description of the metabolic phenotype of mammalian cells using NMR spectroscopy. We discuss all key steps of the process, starting from the selection of the appropriate culture medium, quenching techniques to arrest metabolism in a reproducible manner, the extraction of the intracellular components and the profiling of the culture medium. NMR data acquisition and methods for both qualitative and quantitative analysis are also provided. The suggested methods cover experiments for adherent cells and cells in suspension. We ultimately describe the application of the discussed workflow to a thyroid cancer cell line. Although this tutorial focuses on mammalian cells, the given guidelines and procedures may be adjusted for the analysis of other cell types.
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      PubDate: 2017-06-15T03:27:53Z
      DOI: 10.1016/j.aca.2017.05.011
      Issue No: Vol. 980 (2017)
  • Analysis of stable isotope assisted metabolomics data acquired by GC-MS
    • Authors: Xiaoli Wei; Biyun Shi; Imhoi Koo; Xinmin Yin; Pawel Lorkiewicz; Hamid Suhail; Ramandeep Rattan; Shailendra Giri; Craig J. McClain; Xiang Zhang
      Pages: 25 - 32
      Abstract: Publication date: 8 August 2017
      Source:Analytica Chimica Acta, Volume 980
      Author(s): Xiaoli Wei, Biyun Shi, Imhoi Koo, Xinmin Yin, Pawel Lorkiewicz, Hamid Suhail, Ramandeep Rattan, Shailendra Giri, Craig J. McClain, Xiang Zhang
      Stable isotope assisted metabolomics (SIAM) measures the abundance levels of metabolites in a particular pathway using stable isotope tracers (e.g., 13C, 18O and/or 15N). We report a method termed signature ion approach for analysis of SIAM data acquired on a GC-MS system equipped with an electron ionization (EI) ion source. The signature ion is a fragment ion in EI mass spectrum of a derivatized metabolite that contains all atoms of the underivatized metabolite, except the hydrogen atoms lost during derivatization. In this approach, GC-MS data of metabolite standards were used to recognize the signature ion from the EI mass spectra acquired from stable isotope labeled samples, and a linear regression model was used to deconvolute the intensity of overlapping isotopologues. A mixture score function was also employed for cross-sample chromatographic peak list alignment to recognize the chromatographic peaks generated by the same metabolite in different samples, by simultaneously evaluating the similarity of retention time and EI mass spectrum of two chromatographic peaks. Analysis of a mixture of 16 13C-labeled and 16 unlabeled amino acids showed that the signature ion approach accurately identified and quantified all isotopologues. Analysis of polar metabolite extracts from cells respectively fed with uniform 13C-glucose and 13C-glutamine further demonstrated that this method can also be used to analyze the complex data acquired from biological samples.
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      PubDate: 2017-06-15T03:27:53Z
      DOI: 10.1016/j.aca.2017.05.002
      Issue No: Vol. 980 (2017)
  • Rapid determination of nitrate in vegetables by gas chromatography mass
    • Authors: Beatrice Campanella; Massimo Onor; Enea Pagliano
      Pages: 33 - 40
      Abstract: Publication date: 8 August 2017
      Source:Analytica Chimica Acta, Volume 980
      Author(s): Beatrice Campanella, Massimo Onor, Enea Pagliano
      In this study we present a novel isotope dilution gas chromatography method for the determination of nitrate in vegetables. The analyte was extracted in water at 70 ∘ C and mixed with 15N isotopically enriched nitrate internal standard. The sample was centrifuged and the supernatant reacted with sulfamic acid for removal of nitrite, and with triethyloxonium tetrafluoroborate for converting nitrate into volatile EtONO 2 . This simple aqueous chemistry allowed for separation of analyte from sample matrix in the form of a gaseous derivative which could be sampled in the headspace before GC–MS analysis. This key-feature of the method made possible the collection of clean chromatograms within an elution time of only 1.8 min. Detection of EtONO2 could be performed using electron impact ionization with a standard GC–MS setup. The method was optimized and validated for the analysis of nitrate in fresh vegetables in the 10-10,000 μg/g range with a detection limit of 2 μg/g. Due to the use of primary isotope dilution quantitation, traceable results of high-precision were attained.
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      PubDate: 2017-06-15T03:27:53Z
      DOI: 10.1016/j.aca.2017.04.053
      Issue No: Vol. 980 (2017)
  • Rapid multiplex DNA amplification on an inexpensive microdevice for human
           identification via short tandem repeat analysis
    • Authors: Jacquelyn A. DuVall; Delphine Le Roux; Brandon L. Thompson; Christopher Birch; Daniel A. Nelson; Jingyi Li; Daniel L. Mills; An-chi Tsuei; Martin G. Ensenberger; Cindy Sprecher; Douglas R. Storts; Brian E. Root; James P. Landers
      Pages: 41 - 49
      Abstract: Publication date: 8 August 2017
      Source:Analytica Chimica Acta, Volume 980
      Author(s): Jacquelyn A. DuVall, Delphine Le Roux, Brandon L. Thompson, Christopher Birch, Daniel A. Nelson, Jingyi Li, Daniel L. Mills, An-chi Tsuei, Martin G. Ensenberger, Cindy Sprecher, Douglas R. Storts, Brian E. Root, James P. Landers
      Forensic DNA analysis requires several steps, including DNA extraction, PCR amplification, and separation of PCR fragments. Intuitively, there are numerous situations where it would be beneficial to speed up the overall DNA analysis process; in this work, we focus on the most time-consuming component in the analysis pipeline, namely the polymerase chain reaction (PCR). Primers were specially designed to target 10 human genomic loci, all yielding amplicons shorter than 350 bases, for ease of downstream integration with on-board microchip electrophoresis. Primer concentrations were adjusted specifically for microdevice amplification, resulting in well-balanced short tandem repeat (STR) profiles. Furthermore, studies were performed to push the limits of the DNA polymerase to achieve rapid, multiplexed PCR on various substrates, including transparent and black polyethylene terephthalate (Pe), and with two distinct adhesives, toner and heat sensitive adhesive (HSA). Rapid STR-based multiplexed PCR amplification is demonstrated in 15 min on a Pe microdevice using a custom-built system for fluid flow control and thermocycling for the full 10-plex, and in 10 min for a smaller multiplex consisting of six core CODIS loci plus Amelogenin with amplicons shorter than 200bp. Lastly, preliminary studies indicate the capability of this PCR microdevice platform to be integrated with both upstream DNA extraction, and downstream microchip electrophoresis. This, coupled to the use of reagents that are compatible with lyophilization (lyo-compatible) for PCR, represents the potential for a fully integrated rotationally-driven microdevice for complete forensic DNA analysis.
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      PubDate: 2017-06-15T03:27:53Z
      DOI: 10.1016/j.aca.2017.04.051
      Issue No: Vol. 980 (2017)
  • Lab on paper chip integrated with Si@GNRs for electroanalysis of diazepam
    • Authors: Jagriti Narang; Chaitali Singhal; Ashish Mathur; Manika Khanuja; Ankur Varshney; Kartikey Garg; Tulika Dahiya; C.S. Pundir
      Pages: 50 - 57
      Abstract: Publication date: 8 August 2017
      Source:Analytica Chimica Acta, Volume 980
      Author(s): Jagriti Narang, Chaitali Singhal, Ashish Mathur, Manika Khanuja, Ankur Varshney, Kartikey Garg, Tulika Dahiya, C.S. Pundir
      We describe herein the fabrication of an electrochemical microfluidic paper based device (EμPAD) for the detection of diazepam, a sedative, anxiety-relieving and muscle-relaxing drug. To achieve it, silica coated gold nanorods (Si@GNRs) were synthesized and drop casted on an electrochemical microfluidic paper based device (EμPAD) for the detection of diazepam. The synthesized composites were characterized by recording its images in scanning electron microscope (SEM) and transmission electron microscope (TEM). The experimental results confirmed that Si@GNRs had good electrocatalytic activity towards diazepam. The modified paper based electrode showed a stable electrochemical response for diazepam in the concentration range of 3.5 nM to 3.5 mM. EμPAD offers many advantageous features such as facile approach, economical and have potential for commercialization. Si@GNRs modified EμPAD was also employed for determination of diazepam in spiked human urine samples. Reported facile lab paper approach integrated with Si@GNRs could be well applied for the determination of serum metabolites.
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      PubDate: 2017-06-15T03:27:53Z
      DOI: 10.1016/j.aca.2017.05.006
      Issue No: Vol. 980 (2017)
  • G-quadruplex based Exo III-assisted signal amplification aptasensor for
           the colorimetric detection of adenosine
    • Authors: Lei Xu; Xin Shen; Bingzhi Li; Chunhong Zhu; Xuemin Zhou
      Pages: 58 - 64
      Abstract: Publication date: 8 August 2017
      Source:Analytica Chimica Acta, Volume 980
      Author(s): Lei Xu, Xin Shen, Bingzhi Li, Chunhong Zhu, Xuemin Zhou
      Adenosine is an endogenous nucleotide pivotally involved in nucleic acid and energy metabolism. Its excessive existence may indicate tumorigenesis, typically lung cancer. Encouraged by its significance as the clinical biomarker, sensitive assay methods towards adenosine have been popularized, with high cost and tedious procedures as the inevitable defects. Herein, we report a label-free aptamer-based exonuclease III (Exo III) amplification colorimetric aptasensor for the highly sensitive and cost-effective detection of adenosine. The strategy employed two unlabeled hairpin DNA oligonucleotides (HP1 and HP2), where HP1 contained the aptamer towards adenosine and HP2 embedded the guanine-rich sequence (GRS). In the presence of adenosine, hairpin HP1 could form specific binding with adenosine and trigger the unfolding of HP1's hairpin structure. The resulting adenosine-HP1 complex could hybridize with HP2, generating the Exo III recognition site. After Exo III-assisted degradation, the GRS was released from HP2, and the adenosine-HP1 was released back to the solution to combine another HP2, inducing the cycling amplification. After multiple circulations, the released ample GRSs were induced to form G-quadruplex, further catalyzing the oxidation of TMB, yielding a color change which was finally mirrored in the absorbance change. On the contrary, the absence of adenosine failed to unfold HP1, remaining color unchanged eventually. Thanks to the amplification strategy, the limit of detection was lowered to 17 nM with a broad linear range from 50 nM to 6 μM. The proposed method was successfully applied to the detection of adenosine in biological samples and satisfying recoveries were acquired.
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      PubDate: 2017-06-15T03:27:53Z
      DOI: 10.1016/j.aca.2017.05.015
      Issue No: Vol. 980 (2017)
  • Nanomolar sensitive colorimetric assay for Mn2+ using cysteic acid-capped
           silver nanoparticles and theoretical investigation of its sensing
    • Authors: Yan-Xia Qi; Zhi-bei Qu; Qi-Xian Wang; Min Zhang; Guoyue Shi
      Pages: 65 - 71
      Abstract: Publication date: 8 August 2017
      Source:Analytica Chimica Acta, Volume 980
      Author(s): Yan-Xia Qi, Zhi-bei Qu, Qi-Xian Wang, Min Zhang, Guoyue Shi
      A new facile, rapid, sensitive and selective colorimetric assay is proposed for the determination of manganese ions (Mn2+) utilizing cysteic acid (CA)-capped silver nanoparticles (CA-AgNPs) as colorimetric probes. The CA-AgNPs were prepared by reducing AgNO3 with NaBH4 in the presence of CA as the capping ligand. The presence of Mn2+ induces the quick aggregation of CA-AgNPs, associated with notable color changes of the CA-AgNPs solution from yellow to dark green. The Mn2+ can form a coordinated structure with CA capping on the AgNPs and leads to formation of large particles aggregation. We also used density functional theory (DFT) to calculate the change of the Gibbs free energy (ΔG) of the interactions between the CA-AgNPs and various metal ions, which shows that CA-AgNPs have high specificity for Mn2+. The high sensitivity and selectivity for Mn2+ were achieved and the detection limit is as low as 5 nM. Furthermore, the proposed method was successfully applied in detecting Mn2+ in a rat model of focal ischemia and the results indicate that our proposed method has great potential for practical applications.
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      PubDate: 2017-06-15T03:27:53Z
      DOI: 10.1016/j.aca.2017.05.018
      Issue No: Vol. 980 (2017)
  • Graphitic carbon nitride supported platinum nanocomposites for rapid and
           sensitive colorimetric detection of mercury ions
    • Authors: Yi-Wei Wang; Lixing Wang; Fengping An; Hui Xu; Zejin Yin; Shurong Tang; Huang-Hao Yang; Hongbo Song
      Pages: 72 - 78
      Abstract: Publication date: 8 August 2017
      Source:Analytica Chimica Acta, Volume 980
      Author(s): Yi-Wei Wang, Lixing Wang, Fengping An, Hui Xu, Zejin Yin, Shurong Tang, Huang-Hao Yang, Hongbo Song
      In this study, graphitic carbon nitride supported platinum nanocomposites (g-C3N4/PtNPs) have been synthesized for the first time by an ultrasonic-assisted chemical reduction method. By using g-C3N4 as the stabilizer, Pt ions could be reduced to PtNPs by NaBH4 and uniformly deposited on the surface of g-C3N4. The resulting g-C3N4/PtNPs exhibited enhanced catalytic activity for the oxidation of 3,3′,5,5’-tetramethylbenzidine (TMB) compared to that of g-C3N4 or PtNPs alone. After interaction with Hg2+, the catalytic activity of g-C3N4/PtNPs was effectively inhibited due to the formation of HgPt amalgam. On the basis of this effect, a novel label free colorimetric sensor has been developed for sensitive detection of Hg2+ through the g-C3N4/PtNPs mediated catalytic reaction. A detection limit as low as 1.23 nM was achieved. This assay also exhibited excellent selectivity toward Hg2+ over other metal ions. In addition, it was successfully applied to the determination of Hg2+ in real water samples. In view of the advantages, such as simple operation, cost-effective, rapid response and naked-eye observation, the developed colorimetric sensor hold great potential for the detection of toxic Hg2+ in environmental and biological samples.
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      PubDate: 2017-06-15T03:27:53Z
      DOI: 10.1016/j.aca.2017.05.019
      Issue No: Vol. 980 (2017)
  • New horizons in the extraction of bioactive compounds using deep eutectic
           solvents: A review
    • Authors: Mohamad Hamdi Zainal-Abidin; Maan Hayyan; Adeeb Hayyan; Natesan Subramanian Jayakumar
      Pages: 1 - 23
      Abstract: Publication date: 1 August 2017
      Source:Analytica Chimica Acta, Volume 979
      Author(s): Mohamad Hamdi Zainal-Abidin, Maan Hayyan, Adeeb Hayyan, Natesan Subramanian Jayakumar
      With the rapid development of ionic liquid analogues, termed ‘deep eutectic solvents’ (DESs), and their application in a wide range of chemical and biochemical processes in the past decade, the extraction of bioactive compounds has attracted significant interest. Recently, numerous studies have explored the extraction of bioactive compounds using DESs from diverse groups of natural sources, including animal and plant sources. This review summarizes the-state-of-the-art effort dedicated to the application of DESs in the extraction of bioactive compounds. The aim of this review also was to introduce conventional and recently-developed extraction techniques, with emphasis on the use of DESs as potential extractants for various bioactive compounds, such as phenolic acid, flavonoids, tanshinone, keratin, tocols, terpenoids, carrageenans, xanthones, isoflavones, α-mangostin, genistin, apigenin, and others. In the near future, DESs are expected to be used extensively for the extraction of bioactive compounds from various sources.
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      PubDate: 2017-06-10T05:22:16Z
      DOI: 10.1016/j.aca.2017.05.012
      Issue No: Vol. 979 (2017)
  • Novel electrochemical immunoassay for human IgG1 using metal sulfide
           quantum dot-doped bovine serum albumin microspheres on
           antibody-functionalized magnetic beads
    • Authors: Zongbao Chen; Minghua Lu
      Pages: 24 - 30
      Abstract: Publication date: 1 August 2017
      Source:Analytica Chimica Acta, Volume 979
      Author(s): Zongbao Chen, Minghua Lu
      A new magneto-controlled electrochemical immunosensing system was developed for the sensitive detection of low-abundance protein (IgG1 used in this case) with a sandwich-type assay format on monoclonal mouse anti-human Fab-specific IgG1-functionalized magnetic bead. Metal sulfide (CdS) quantum dot-doped bovine serum albumin (QD-BSA) was synthesized and functionalized with monoclonal Fc-specific anti-human antibody. In the presence of IgG1, the immobilized antibody on magnetic bead was selective to capture the Fab region of the analyte, followed to be sandwiched by the conjugated antibody onto QD-BSA. The subsequent anodic stripping voltammetric analysis of cadmium ion, released by acid from quantum dot, was conducted at an in situ prepared mercury film electrode. Under optimal conditions, the voltammetric current increased with the increasing of target IgG1 within a dynamic working range from 10 pg mL−1 to 100 ng mL−1. The limit of detection of this immunosensor was evaluated to 3.4 pg mL−1 at 3s blank criterion. The precision, selectivity and method accuracy were acceptable. Analysis of human serum samples revealed good accordance with the results obtained by commercial enzyme-linked immunosorbent assay method. Importantly, this concept offers promise for cost-effective analysis of low-abundance cancer biomarkers without the need of natural enzymes.
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      PubDate: 2017-06-10T05:22:16Z
      DOI: 10.1016/j.aca.2017.05.014
      Issue No: Vol. 979 (2017)
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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