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Publisher: Elsevier   (Total: 3043 journals)

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Showing 1 - 200 of 3043 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 22, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 21, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 84, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 25, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 30, 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: 354, 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: 236, 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: 10, 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: 4)
Acute Pain     Full-text available via subscription   (Followers: 13)
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: 7, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 21)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 137, 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: 17, 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: 11, 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: 26, 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: 9, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 29, 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 Dermatology     Full-text available via subscription   (Followers: 12)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 6)
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: 41, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 50, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
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: 22, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 0.497, h-index: 31)
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: 6)
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: 8, 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: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 61)
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: 3, SJR: 0.1, h-index: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 355, 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: 17)
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: 327, 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: 407, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 16, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 30, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 39, 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: 54, 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: 11, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 8)
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)
Alpha Omegan     Full-text available via subscription   (SJR: 0.121, h-index: 9)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 8, 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: 6)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 49, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 47, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 39, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 8, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 15, 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: 25, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 32, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 45, 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: 234, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 58, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5)
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: 25, 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: 22, 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: 57, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 11)
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: 4, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 37, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 168, 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: 162, 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]   [37 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]
  • Dual-target inhibitor screening against thrombin and factor Xa
           simultaneously by mass spectrometry
    • Authors: Zhe Xu; Ruonan Liu; Huashi Guan
      Pages: 1 - 10
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Zhe Xu, Ruonan Liu, Huashi Guan
      An accurate, rapid, and cost-effective methodology for enzyme assay is highly demanded to screen the effect of compounds on target at the molecular level. Thrombin (EC 3.4.21.5) and factor Xa (FXa, EC 3.4.21.6) have been identified as the critical targets for the development of potential drugs with anticoagulant activity. In this study, a rapid, sensitive and accurate assay based on UHPLC-MS/MS method has been developed for inhibitor screening against thrombin and factor Xa simultaneously. For thrombin and factor Xa, the Michaelis-Menten constants (K m ) were calculated to be 6.14 and 57.27 μM, respectively. The inhibition constants (K i ) for two known inhibitors, argatroban and rivaroxaban, were determined to be 16.23 and 0.41 nM, respectively. The assay was further validated through the determination of a high Z′ factor value of 0.89. Finally, the developed assay was applied to screen a chemical library against two enzymes. Three hit compounds belonging to a class of sulfated polysaccharides were identified and their targets of inhibition action were further evaluated. The results indicated that the dual-target assay by UHPLC-MS/MS analysis could be used as a reliable method for screening anticoagulant agents.
      Graphical abstract image

      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.063
      Issue No: Vol. 990 (2017)
       
  • Voltammetric determination of metal ions beyond mercury electrodes. A
           review
    • Authors: Cristina Ariño; Núria Serrano; José Manuel Díaz-Cruz; Miquel Esteban
      Pages: 11 - 53
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Cristina Ariño, Núria Serrano, José Manuel Díaz-Cruz, Miquel Esteban
      For a long time mercury electrodes have been the main choice for the analysis of metal ions and some metalloids. However, in the last years, safety and environmental considerations have restricted their use and encouraged the search for alternative materials more environmentally friendly and with more possibilities for in-situ and flow analysis. This research has been reinforced by the popularisation of nanomaterials, biomolecules and screen-printed electrodes, as well as for the new advances in sensor miniaturization and integration of the electrodes in multi-sensor platforms and electronic tongues. The present review critically summarizes and discusses the progress made since 2010 in the development and application of new electrodes for the analysis of metals and metalloids.
      Graphical abstract image

      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.069
      Issue No: Vol. 990 (2017)
       
  • Advances of Vibrational Circular Dichroism (VCD) in bioanalytical
           chemistry. A review
    • Authors: Dmitry Kurouski
      Pages: 54 - 66
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Dmitry Kurouski
      Vibrational Circular Dichroism (VCD) is a unique and relatively new spectroscopic technique that is capable of determining an absolute configuration of chiral molecules. VCD can be also used to determine structure of large macromolecules. This review highlights the most recent advances of VCD in bioanalytical chemistry. It shows that VCD is capable of unraveling supramolecular organization of peptides, proteins, saccharides, glycerophospholipids, polypeptide microcrystals, as well as amyloid fibrils and DNA. This review also demonstrates how VCD can be utilized to explore molecule-molecule interactions that determine mechanisms of chiral separations in chromatography. It aims to attract attention of scientists from all different research areas demonstrating the strength and capability of this very powerful spectroscopic technique.
      Graphical abstract image

      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.08.014
      Issue No: Vol. 990 (2017)
       
  • Hydrogels of polyaniline with graphene oxide for highly sensitive
           electrochemical determination of lead ions
    • Authors: S. Muralikrishna; D.H. Nagaraju; R. Geetha Balakrishna; Werasak Surareungchai; T. Ramakrishnappa; Avinash B. Shivanandareddy
      Pages: 67 - 77
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): S. Muralikrishna, D.H. Nagaraju, R. Geetha Balakrishna, Werasak Surareungchai, T. Ramakrishnappa, Avinash B. Shivanandareddy
      Conducting polymers with graphene/graphene oxide hydrogels represent a unique class of electrode materials for sensors and energy storage applications. In this article, we report a facile in situ method for the polymerisation of aniline resulting in the decoration of 1D conducting polyaniline (PANI) nanofibers onto the surface of 2D graphene oxide (GO) nanosheets followed by hydrogel formation at elevated temperature. The synthesized nanomaterial exhibits significant properties for the highly sensitive electrochemical determination as well as removal of environmentally harmful lead (Pb2+) ions. The square wave anodic stripping voltammetry (SWASV) determination of Pb2+ ions showed good electroanalytical performance with two linear ranges in 0.2–250 nM (correlation coefficient = 0.996) and 250–3500 nM (correlation coefficient = 0.998). The developed protocol has shown a limit of detection (LOD) of about 0.04 nM, which is much lower than that of the World Health Organization (WHO) threshold limits. The prepared electrode showed an average of ∼99.4% removal of Pb2+ ions with a relative standard deviation (RSD) of 3.4%. Selectivity of the electrode towards Pb2+ ions were tested in presence of potential interferences such as Na+, K+, Ca2+, Mg2+, Cu2+, Cd2+, Hg2+, Zn2+, Co2+, Ni2+, Fe2+ and Fe3+ of similar and higher concentrations. The sensor showed good repeatability and reproducibility. The developed protocol was used to analyse samples from industrial effluents and natural water samples. The results obtained were correlated with atomic absorption spectroscopy (AAS).
      Graphical abstract image

      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.09.008
      Issue No: Vol. 990 (2017)
       
  • Synthesis of robust electrochemical substrate and fabrication of
           immobilization free biosensors for rapid sensing of salicylate and
           β-hydroxybutyrate in whole blood
    • Authors: Ting-Yo Chen; Veerappan Mani; Sheng-Tung Huang; Pu-Chieh Chang; Chih-Hung Huang; Nay Ming Huang
      Pages: 78 - 83
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Ting-Yo Chen, Veerappan Mani, Sheng-Tung Huang, Pu-Chieh Chang, Chih-Hung Huang, Nay Ming Huang
      An electrochemical latent redox probe, SAF 5 was designed, synthesized and characterized. A rapid and sensitive solution-based assay was demonstrated for salicylate hydroxylase (SHL). In presence of NADH at aerobic conditions, SHL catalyzed the decarboxylative hydroxylation of SAF and released a redox reporter amino ferrocene (AF 6). The release of AF 6 was monitored at interference free potential region (–50 mV vs. Ag AgCl) using differential pulse voltammetry as signal read-out. The current signal generated by this process is highly specific, and insensitive to other biological interfering compounds. Next, the SAF incorporated SHL assay was extended to fabricate immobilization-free biosensors for rapid sensing of salicylic acid (SA) and β-hydroxybutyrate (β-HB) in whole blood. The described method rapidly detects SA in a linear range of 35–560 μM with detection limit of 5.0 μM. For β-HB determination, the linear range was 10–600 μM and detection limit was 2.0 μM. Besides, the assay protocols are simple, fast, reliable, selective, sensitive and advantageous over existing methods. The whole blood assay did not required cumbersome steps such as, enzyme immobilization, pre-treatments and holds great practical potential in clinical diagnosis.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.08.051
      Issue No: Vol. 990 (2017)
       
  • Liquid chromatography tandem mass spectrometric determination of
           triterpenes in human fluids: Evaluation of markers of dietary intake of
           olive oil and metabolic disposition of oleanolic acid and maslinic acid in
           humans
    • Authors: Oscar J. Pozo; Mitona Pujadas; Sarah Biel Gleeson; Maria Dolores Mesa-García; Antoni Pastor; Aristotelis Kotronoulas; Montserrat Fitó; Maria-Isabel Covas; José Ramón Fernández Navarro; Juan Antonio Espejo; Estefania Sanchez-Rodriguez; Rosa Marchal; Miguel Angel Calleja; Rafael de la Torre
      Pages: 84 - 95
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Oscar J. Pozo, Mitona Pujadas, Sarah Biel Gleeson, Maria Dolores Mesa-García, Antoni Pastor, Aristotelis Kotronoulas, Montserrat Fitó, Maria-Isabel Covas, José Ramón Fernández Navarro, Juan Antonio Espejo, Estefania Sanchez-Rodriguez, Rosa Marchal, Miguel Angel Calleja, Rafael de la Torre
      Olive oil is rich in several minor components like maslinic (MA) and oleanolic (OA) acids which have cardioprotective, antitumor, and anti-inflammatory properties. In order to assess the health benefits in humans provided by the olive oil triterpenes (MA and OA), suitable analytical methods able to quantify the low concentrations expected in human fluids are required. In this study, the LC-MS/MS quantification of both OA and MA in plasma and urine has been evaluated. The plasmatic method is based on the direct determination of the analytes. The urinary detection requires more sensitivity which was reached by derivatization with 2-picolylamine. Additionally, the urinary species present after MA and OA ingestion were evaluated by the direct detection of several phase II metabolites previously synthesized. Our results showed that OA is metabolized as both sulfate and glucuronide conjugates whereas MA is mainly excreted as glucuronide. Based on this information, the method for the urinary detection of MA and OA involved an enzymatic hydrolysis. Both plasmatic and urinary methods were validated with suitable precision and accuracy at all tested levels. Required sensitivity was achieved in both matrices. Up to our knowledge, this is the first method able to quantify the low concentration levels of triterpenes present in urine. Samples from two healthy volunteers who received virgin olive oils with different triterpenes content were analyzed. Some preliminary clues on the metabolic disposition of OA and MA after olive oil intake are provided.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.041
      Issue No: Vol. 990 (2017)
       
  • An alignment algorithm for LC-MS-based metabolomics dataset assisted by
           MS/MS information
    • Authors: Lili Li; Weijie Ren; Hongwei Kong; Chunxia Zhao; Xinjie Zhao; Xiaohui Lin; Xin Lu; Guowang Xu
      Pages: 96 - 102
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Lili Li, Weijie Ren, Hongwei Kong, Chunxia Zhao, Xinjie Zhao, Xiaohui Lin, Xin Lu, Guowang Xu
      Liquid chromatography-mass spectrometry (LC-MS) is an important analytical platform for metabolomics study. Peak alignment of metabolomics dataset is one of the keys for a successful metabolomics study. In this work, a MS/MS-based peak alignment method for LC-MS metabolomics data was developed. A rigorous strategy for screening endogenous reference variables was proposed. Firstly, candidate endogenous reference variables were selected based on MS, MS/MS and retention time in all samples. Multiple robust endogenous reference variables were obtained through further evaluation and confirmation. Then retention time of each metabolite feature was corrected by local linear regression using the four nearest neighbor robust reference variables. Finally, peak alignment was carried out based on corrected retention time, MS and MS/MS. Comparing with the other two peak alignment methods, the developed method showed a good performance and was suitable for metabolomics data with larger retention time drift. Our approach provides a simple and robust alignment method which is reliable to align LC-MS metabolomics dataset.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.058
      Issue No: Vol. 990 (2017)
       
  • Determination of cyanocobalamin by isotope dilution LC-MS/MS
    • Authors: Lucia D'Ulivo; Lu Yang; Jianfu Ding; Enea Pagliano; Donald M. Leek; Marie-Pier Thibeault; Zoltán Mester
      Pages: 103 - 109
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Lucia D'Ulivo, Lu Yang, Jianfu Ding, Enea Pagliano, Donald M. Leek, Marie-Pier Thibeault, Zoltán Mester
      Cyanocobalamin (CNCbl) is an active form of vitamin B12, commonly employed for the preparation of multivitamin supplements and fortified food. In this study, we present a novel analytical method for its determination based on stable isotope dilution liquid chromatography electrospray tandem mass spectrometry (ID LC-MS/MS). Isotopically enriched 13C15NCbl was synthesized in-house and used as internal standard. The method was validated using NIST SRM 3280 multivitamin reference material and by comparison with an independent methodology based on LC-ICPMS. The proposed method provided a detection limit of 57 pg/g and could be applied for the determination of trace level of CNCbl in multivitamin supplements with a relative standard uncertainty better than 3%. The novel ID LC-MS/MS is a primary ratio method that could become a reference for CNCbl determination in multivitamins and food supplements. The method was applied for the characterization of two NRC multivitamin tablet Certified Reference Material (CRM) candidates, VITA-1 and VITB-1 whose CNCbl levels were quantified as 2.64 ± 0.09 and 1.75 ± 0.12 μg/g, respectively.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.065
      Issue No: Vol. 990 (2017)
       
  • 3D lung spheroid cultures for evaluation of photodynamic therapy (PDT)
           procedures in microfluidic Lab-on-a-Chip system
    • Authors: Agnieszka Zuchowska; Elzbieta Jastrzebska; Michal Chudy; Artur Dybko; Zbigniew Brzozka
      Pages: 110 - 120
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Agnieszka Zuchowska, Elzbieta Jastrzebska, Michal Chudy, Artur Dybko, Zbigniew Brzozka
      The purpose of this paper is to present a fully integrated microchip for the evaluation of PDT procedures efficiency on 3D lung spheroid cultures. Human lung carcinoma A549 and non-malignant MRC-5 spheroids were utilized as culture models. Spheroid viability was evaluated 24 h after PDT treatment, in which 5-aminolevulinic acid (ALA) had been used as a precursor of a photosensitizer (protoporphyrin IX – PpIX). Moreover, spheroid viability over a long-term (10-day) culture was also examined. We showed that the proposed PDT treatment was toxic only for cancer spheroids. This could be because of a much-favoured enzymatic conversion of ALA to PpIX in cancer as opposed normal cells. Moreover, we showed that to obtain high effectiveness of ALA-PDT on lung cancer spheroids additional time of spheroid after light exposure was required. It was found that PDT had been effective 5 days after PDT treatment with 3 mM ALA. To the best of our knowledge this has been the first presentation of such research performed on a 3D lung spheroids culture in a microfluidic system.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.009
      Issue No: Vol. 990 (2017)
       
  • Reduction of production rate in Y-shaped microreactors in the presence of
           viscoelasticity
    • Authors: Hamed Helisaz; Mohammad Hassan Saidi; Arman Sadeghi
      Pages: 121 - 134
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Hamed Helisaz, Mohammad Hassan Saidi, Arman Sadeghi
      The viscoelasticity effects on the reaction-diffusion rates in a Y-shaped microreactor are studied utilizing the PTT rheological model. The flow is assumed to be fully developed and considered to be created under a combined action of electroosmotic and pressure forces. In general, finite-volume-based numerical simulations are conducted to handle the problem; however, analytical solutions based on the depthwise averaging approach are also obtained for the case for which there is no reaction between the inlet components. The analytical solutions are found to predict accurate results when the width to height ratio is at least 10 and acceptable results for lower aspect ratios. An investigation of the viscoelasticity effect reveals that it is accompanied by a significant reduction of the production rate and the production efficiency, defined as the ratio of the average product concentration to the inlet concentration of the limiting reactant. In addition, this effect gives rise to a more uniform transport with more symmetric concentration distributions. The pressure effects on the reaction-diffusion rates are also pronounced in the presence of viscoelasticity. Finally, the influences of the product diffusivity are investigated for the first time revealing that the lower it is the thinner the area of significant production becomes.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.08.041
      Issue No: Vol. 990 (2017)
       
  • Rapid visual and spectrophotometric nitrite detection by cyclometalated
           ruthenium complex
    • Authors: Hoi-Shing Lo; Ka-Wai Lo; Chi-Fung Yeung; Chun-Yuen Wong
      Pages: 135 - 140
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Hoi-Shing Lo, Ka-Wai Lo, Chi-Fung Yeung, Chun-Yuen Wong
      Quantitative determination of nitrite ion (NO2 −) is of great importance in environmental and clinical investigations. A rapid visual and spectrophotometric assay for NO2 − detection was developed based on a newly designed ruthenium complex, [Ru(npy)([9]aneS3)(CO)](ClO4) (denoted as RuNPY; npy = 2-(1-naphthyl)pyridine, [9]aneS3 = 1,4,7-trithiacyclononane). This complex traps NO+ produced in acidified NO2 − solution, and yields observable color change within 1 min at room temperature. The assay features excellent dynamic range (1–840 μmol L−1) and high selectivity, and its limit of detection (0.39 μmol L−1) is also well below the guideline values for drinking water recommended by WHO and U.S. EPA. Practical use of this assay in tap water and human urine was successfully demonstrated. Overall, the rapidity and selectivity of this assay overcome the problems suffered by the commonly used modified Griess assays for nitrite determination.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.018
      Issue No: Vol. 990 (2017)
       
  • Surface enhanced infrared absorption spectroscopy based on gold nanostars
           and spherical nanoparticles
    • Authors: Olga Bibikova; Julian Haas; Ángela I. López-Lorente; Alexey Popov; Matti Kinnunen; Yury Ryabchikov; Andrei Kabashin; Igor Meglinski; Boris Mizaikoff
      Pages: 141 - 149
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Olga Bibikova, Julian Haas, Ángela I. López-Lorente, Alexey Popov, Matti Kinnunen, Yury Ryabchikov, Andrei Kabashin, Igor Meglinski, Boris Mizaikoff
      Plasmonic anisotropic nanoparticles possess a number of hot spots on their surface due to the presence of sharp edges, tips or vertices, leading to a high electric field strength surrounding the nanostructures. In this paper, we explore different plasmonic nanostructures, including anisotropic gold nanostars (AuNSts) and spherical gold nanoparticles, in surface-enhanced infrared absorption spectroscopy (SEIRAS) in an attenuated total reflection (ATR) configuration. In our experiments, we observed up to 10-times enhancement of the infrared (IR) absorption of thioglycolic acid (TGA) and up to 2-times enhancement of signals for bovine serum albumin (BSA) protein on plasmonic nanostructure-based films deposited on a silicon (Si) internal reflection element (IRE) compared to bare Si IRE. The dependence of the observed enhancement on the amount of AuNSts present at the surface of the IRE has been demonstrated. Quantitative studies with both, TGA and BSA were performed, observing that the SEIRA signal can be correlated to the concentration of analyte molecules present within the evanescent field. The calibration curves in the presence of the AuNSts showed enhanced sensitivity as compared with the bare Si IRE. We finally compare efficiencies of anisotropic AuNSts and spherical citrate-capped and “bare” laser-synthesized gold nanoparticles as SEIRAS substrates for the detection of TGA and BSA. The signal obtained from AuNSts was at least 2 times higher for TGA molecules in comparison with spherical gold nanoparticles, which was explained by a more efficient generation of hot spots on anisotropic surface due to the presence of sharp edges, tips or vertices, leading to a high electric field strength surrounding the AuNSts.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.045
      Issue No: Vol. 990 (2017)
       
  • A redox-modulated fluorescent strategy for the highly sensitive detection
           of metabolites by using graphene quantum dots
    • Authors: Hua Liu; Xing Li; Mengke Wang; Xueqian Chen; Xingguang Su
      Pages: 150 - 156
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Hua Liu, Xing Li, Mengke Wang, Xueqian Chen, Xingguang Su
      In this paper, a redox-modulated fluorescent strategy based on the transformation of Fe2+/Fe3+ couple and enzymatic reaction for rapid monitoring glucose and uric acid using graphene quantum dots (GQDs) as fluorescent probe was developed. Hydrogen peroxide (H2O2) can be produced by the enzymatic reaction of a series of metabolites, such as glucose and uric acid. In the presence of hydrogen peroxide, Fe2+ can be oxidized and converted to Fe3+, which have a significant quenching difference in the fluorescence of graphene quantum dots (GQDs). Thus, a sensitive and label-free biosensor for the detection of uric acid and glucose was developed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of uric acid and glucose in the range of 0.1–45 μmolL-1 and 0.1–30 μmolL-1 with a detection limit of 0.026 μmolL−1and 0.021 μmolL−1, respectively. The proposed method was applied to the determination of uric acid and glucose in human serum samples with satisfactory results, which had potential application to detect metabolites associated with H2O2 release.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.031
      Issue No: Vol. 990 (2017)
       
  • Studying the influence of stem composition in pH-sensitive molecular
           beacons onto their sensing properties
    • Authors: Anna Dembska; Elzbieta Kierzek; Bernard Juskowiak
      Pages: 157 - 167
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Anna Dembska, Elzbieta Kierzek, Bernard Juskowiak
      Intracellular sensing using fluorescent molecular beacons is a potentially useful strategy for real-time, in vivo monitoring of important cellular events. This work is focused on evaluation of pyrene excimer signaling molecular beacons (MBs) for the monitoring of pH changes in vitro as well as inside living cells. The recognition element in our MB called pHSO (pH-sensitive oligonucleotide) is the loop enclosing cytosine-rich fragment that is able to form i-motif structure in a specific pH range. However, alteration of a sequence of the 6 base pairs containing stem of MB allowed the design of pHSO probes that exhibited different dynamic pH range and possessed slightly different transition midpoint between i-motif and open loop configuration. Moreover, this conformational transition was accompanied by spectral changes showing developed probes different pyrene excimer-monomer emission ratio triggered by pH changes. The potential of these MBs for intracellular pH sensing is demonstrated on the example of HeLa cells line.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.040
      Issue No: Vol. 990 (2017)
       
  • A quantitative homogeneous assay for global DNA methylation levels using
           CpG-binding domain- and methyl-CpG-binding domain-fused luciferase
    • Authors: Wataru Yoshida; Yuji Baba; Kyoko Banzawa; Isao Karube
      Pages: 168 - 173
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Wataru Yoshida, Yuji Baba, Kyoko Banzawa, Isao Karube
      Global DNA methylation levels have been considered as biomarkers for cancer diagnostics because transposable elements that constitute approximately 45% of the human genome are hypomethylated in cancer cells. We have previously reported a homogeneous assay for measuring methylated CpG content of genomic DNA based on bioluminescence resonance energy transfer (BRET) using methyl-CpG-binding domain (MBD)-fused luciferase (MBD-luciferase). In this study, a homogeneous assay for measuring unmethylated CpG content of genomic DNA in the same platform was developed using CXXC domain-fused luciferase (CXXC-luciferase) that specifically recognizes unmethylated CpG. In this assay, CXXC-luciferase recognizes unmethylated CpG on genomic DNA, whereby BRET between luciferase and the fluorescent DNA intercalating dye is detected. We demonstrated that the BRET signal depended on the genomic DNA concentration (R2 = 0.99) and unmethylated CpG content determined by the bisulfite method (R2 = 0.97). There was a significant negative correlation between the BRET signal of the CXXC-luciferase-based assay and that of the MBD-luciferase-based assay (R2 = 0.92). Moreover, we demonstrated that the global DNA methylation level determined using the bisulfite method was dependent on the ratio of the BRET signal in the MBD-luciferase-based assay to the total BRET signal in the MBD-luciferase- and CXXC-luciferase-based assays (R2 = 0.99, relative standard deviation < 2.2%, and analysis speed < 35 min). These results demonstrated that global DNA methylation levels can be quantified by calculating the BRET signal ratio without any calibration curve.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.046
      Issue No: Vol. 990 (2017)
       
  • Enantioseparation of single layer native cyclodextrin chiral stationary
           phases: Effect of cyclodextrin orientation and a modeling study
    • Authors: Xiaoxuan Li; Xiaobin Yao; Yin Xiao; Yong Wang
      Pages: 174 - 184
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Xiaoxuan Li, Xiaobin Yao, Yin Xiao, Yong Wang
      A novel native cyclodextrin (CD) chiral stationary phase (CSP) with single triazole-bridge at CD C2 position (CSP1) was prepared by anchoring mono(2A-azido-2A-deoxy)-β-CD onto alkynyl silica via click chemistry. The effect of CD orientation on single layer CD-CSP's enantioseparation was comprehensively investigated using CSP1 (reversed orientation) and our previously reported CSP2 (C6 single triazole-bridge, normal orientation) as well as a commercial CD-CSP (Cyclobond I 2000, hybrid orientation) by separating several groups of analytes in chiral high performance liquid chromatography. It is found that the CD orientation on silica surface plays an important role in separating different racemates. CSP2 with normal CD orientation affords best separation for isoxazolines while CSP1 with reversed CD orientation better separates naringenin, hesperetin and Tröger's base. CSP2 and Cyclobond I 2000 show comparable separation ability for dansyl amino acids while poor separation was found on CSP1. Besides, molecular dynamics simulation was performed under “real” separation conditions using flavanone as model analyte to reveal the essential factors for CD's chiral discrimination behaviors.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.07.033
      Issue No: Vol. 990 (2017)
       
  • Preparative isoelectric focusing of microorganisms in cellulose-based
           separation medium and subsequent analysis by CIEF and MALDI-TOF MS
    • Authors: Marie Horká; Karel Šlais; Jiří Šalplachta; Filip Růžička
      Pages: 185 - 193
      Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990
      Author(s): Marie Horká, Karel Šlais, Jiří Šalplachta, Filip Růžička
      Pre-separation and pre-concentration of bacteria is an important step especially when they are uncultured and bacterial concentration in the matrix is low. This study describes a preparative method based on isoelectric focusing of colored microorganisms in a cellulose-based separation medium from a high conductivity matrix. The isoelectric points found for the examined cells were 1.8 for Micrococcus luteus, 3.5 for Dietzia sp., and 4.7 for Rhodotorula mucilaginosa using capillary isoelectric focusing. The final positions of the zones of colored microbial cells in the cellulose-bed are indicated by colored pI markers. Segments of the separation medium with cells were harvested by a spatula, simply purified using centrifugation and analyzed by capillary isoelectric focusing and matrix-assisted laser desorption/ionization time of flight mass spectrometry. The determined recovery ranged from 78% to 93%. The viability of the harvested cells was verified by their cultivation.
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      PubDate: 2017-10-14T11:19:30Z
      DOI: 10.1016/j.aca.2017.08.046
      Issue No: Vol. 990 (2017)
       
  • Secondary ion mass spectrometry: The application in the analysis of
           atmospheric particulate matter
    • Authors: Di Huang; Xin Hua; Guang-Li Xiu; Yong-Jie Zheng; Xiao-Ying Yu; Yi-Tao Long
      Pages: 1 - 14
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Di Huang, Xin Hua, Guang-Li Xiu, Yong-Jie Zheng, Xiao-Ying Yu, Yi-Tao Long
      Currently, considerable attention has been paid to atmospheric particulate matter (PM) investigation due to its importance in human health and global climate change. Surface characterization, single particle analysis and depth profiling of PM is important for a better understanding of its formation processes and predicting its impact on the environment and human being. Secondary ion mass spectrometry (SIMS) is a surface technique with high surface sensitivity, high spatial resolution chemical imaging and unique depth profiling capabilities. Recent research shows that SIMS has great potential in analyzing both surface and bulk chemical information of PM. In this review, we give a brief introduction of SIMS working principle and survey recent applications of SIMS in PM characterization. Particularly, analyses from different types of PM sources by various SIMS techniques were discussed concerning their advantages and limitations. The future development and needs of SIMS in atmospheric aerosol measurement are proposed with a perspective in broader environmental sciences.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.042
      Issue No: Vol. 989 (2017)
       
  • A magnetic field-directed self-assembly solid contact for construction of
           an all-solid-state polymeric membrane Ca2+-selective electrode
    • Authors: Tanji Yin; Xiaojing Jiang; Wei Qin
      Pages: 15 - 20
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Tanji Yin, Xiaojing Jiang, Wei Qin
      A magnetic field-directed self-assembly solid contact has been proposed for developing an all-solid-state polymeric membrane Ca2+-selective electrode. The solid contact is prepared by physically adsorbing magnetic graphene powder on a magnetic gold electrode under the direction of the magnetic field. The proposed method for preparing solid contact avoids using the aqueous solutions and is simple, fast and general as compared to the multilayer drop-casting and electrodeposition methods. The all-solid-state Ca2+-selective electrode based on magnetic graphene as solid contact shows a stable potential response in the linear range of 1.0 × 10−6-1.0 × 10−3 M with a slope of 28.2 mV/decade, and the detection limit is about 4.0 × 10−7 M. Additionally, the magnetic graphene-based electrode shows a comparable potential stability performance to other graphene-based all-solid-state ion-selective electrodes, such as reduced undesirable water layer and insensitive to the interferences of O2, CO2 and light. This work provides a favorable way to prepare solid contact for use in the field of all-solid-state ion-selective electrodes.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.015
      Issue No: Vol. 989 (2017)
       
  • Porous organic polymers with different pore structures for sensitive
           solid-phase microextraction of environmental organic pollutants
    • Authors: Zhoubing Huang; Shuqin Liu; Jianqiao Xu; Li Yin; Juan Zheng; Ningbo Zhou; Gangfeng Ouyang
      Pages: 21 - 28
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Zhoubing Huang, Shuqin Liu, Jianqiao Xu, Li Yin, Juan Zheng, Ningbo Zhou, Gangfeng Ouyang
      Adsorption capacity is the major sensitivity-limited factor in solid-phase microextraction. Due to its light-weight properties, large specific surface area and high porosity, especially tunable pore structures, the utilization of porous organic polymers as solid-phase microextraction adsorbents has attracting researchers' attentions. However, these works mostly concentrated on the utilization of specific porous organic polymers for preparing high-performance solid-phase microextraction coatings. The relationship between pore structures and adsorption performance of the porous organic polymers still remain unclear. Herein, three porous organic polymers with similar properties but different pore distributions were prepared by condensation polymerization reaction of phloroglucinol and terephthalaldehyde, which were fabricated as solid-phase microextraction coatings subsequently. The adsorption capacity of the porous organic polymers-coated fibers were evaluated by using benzene and its derivatives (i.e.,benzene, toluene, ethylbenzene and m-xylene) and polycyclic aromatic hydrocarbons as the target analytes. The results showed that the different adsorption performance of these porous organic polymers was mainly caused by their different pore volumes instead of their surface areas or pore sizes. Finally, the proposed method by using the mesoporous organic polymer coating was successfully applied to the determination of benzene and its derivatives in environmental water samples. As for analytical performance, high pre-concentration factors (74–2984), satisfactory relative recoveries (94.5 ± 18.5–116.9 ± 12.5%), intraday precision (2.44–5.34%), inter-day precision (4.62–7.02%), low limit of detections (LODs, 0.10–0.29 ng L−1) and limit of quantifications (LOQs, 0.33–0.96 ng L−1) were achieved under the optimal conditions. This study provides an important idea in the rational design of porous organic polymers for solid-phase microextraction or other adsorption applications.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.006
      Issue No: Vol. 989 (2017)
       
  • Accurate and reliable quantification of the protein surface coverage on
           protein-functionalized nanoparticles
    • Authors: Siyao Liu; Jeannie Horak; Markus Höldrich; Michael Lämmerhofer
      Pages: 29 - 37
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Siyao Liu, Jeannie Horak, Markus Höldrich, Michael Lämmerhofer
      The ability to accurately quantify the protein coverage on nanoparticles is critical for assessing the quality of the surface chemistry and the success of the functionalization process of protein-nanoparticle conjugates. Surface coverage determination is therefore an integral part in the quality control of protein-modified nanoparticles in industrial nanotechnology. In this work, a novel and conventional method was established for direct quantification of the protein surface coverage on metallic nanoparticles. Different concentrations of pepsin were conjugated to gold nanoparticles (GNPs) by a straightforward adsorptive immobilization process as a model system, and a protein quantitation methodology based on the amino acid analysis of the hydrolysate of the protein-GNP conjugates was established. For this purpose, pepsin functionalized GNPs (pepsin-GNP bioconjugates) were processed via in situ hydrolysis with 6N HCl and subsequent derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC reagent). Direct quantitative amino acid analysis was performed based on measuring the intensity of AQC-glycine derivative by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The method allows for detection of surface coverages as low as 0.1 μg mL−1 pepsin (corresponding to 2.89 × 10−9 mol L−1) in the colloidal solution. Method imprecision for replicated surface coverage determinations was <5% RSD and accuracies, as determined by % recoveries, were always in the 98–118% range. This method allows precise and accurate quantification of protein coverages, even when less than 1% of the protein in the reaction mixture is immobilized. It was found that the degree of surface coverage of adsorptively bound pepsin on GNPs correlated with the pepsin concentrations in the conjugation reaction mixtures. Washing with phosphate buffer removed weakly bound proteins, i.e. the soft protein corona. The adsorption behavior could be described by a Freundlich isotherm model. This direct and reliable method promises great potential for the accurate quantification of protein coverages of various protein-nanoparticle bioconjugates.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.004
      Issue No: Vol. 989 (2017)
       
  • Paper spray and Kendrick mass defect analysis of block and random ethylene
           oxide/propylene oxide copolymers
    • Authors: Robert B. Cody; Thierry Fouquet
      Pages: 38 - 44
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Robert B. Cody, Thierry Fouquet
      Paper spray ionization coupled with a high-resolution time-of-flight mass spectrometer was applied to the analysis of 13 block and 2 random ethylene oxide/propylene oxide (EO/PO) copolymers as well as to standard samples of poly(ethylene oxide) and poly(propylene oxide) homopolymers. Paper spray mass spectra could be obtained rapidly and, unlike electrospray ionization, were not subject to contamination and sample carryover. For comparison, polyether samples were also measured on a MALDI/TOF system with ultrahigh mass resolving power. MALDI/high-resolution time-of-flight mass spectrometry exhibited single-charge ions characteristic of the polymer distributions whereas the paper spray mass spectra exhibited charge states ranging from one to six charges. Kendrick mass defect plots of the multiple-charge ions in the paper spray mass spectra exhibit isotopic splitting of the Kendrick mass defects, facilitating visualization of the number of charges in each series. The slope of the KMD plots can be used to estimate the percentage of ethylene oxide in the copolymers. In-source fragmentation permitted the distinction between block and random copolymers.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.005
      Issue No: Vol. 989 (2017)
       
  • Development of a validated LC- MS/MS method for the quantification of 19
           endogenous asthma/COPD potential urinary biomarkers
    • Authors: Mona M. Khamis; Darryl J. Adamko; Anas El-Aneed
      Pages: 45 - 58
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Mona M. Khamis, Darryl J. Adamko, Anas El-Aneed
      Obstructive airways inflammatory diseases sometimes show overlapping symptoms that hinder their early and correct diagnosis. Current clinical tests are tedious and are of inadequate specificity in special population such as the elderly and children. Therefore, we are developing tandem mass spectrometric (MS/MS) methods for targeted analysis of urine biomarkers. Recently, proton-nuclear magnetic resonance (1H-NMR) analysis proposed 50 urinary metabolites as potential diagnostic biomarkers among asthma and chronic obstructive pulmonary disease (COPD) patients. Metabolites are divided into 3 groups based on chemical nature. For group 1 (amines and phenols, 19 urinary metabolites), we developed and validated a high performance liquid chromatographic (HPLC)-MS/MS method using differential isotope labeling (DIL) with dansyl chloride. Method development included the optimization of the derivatization reaction, the MS/MS conditions, and the chromatographic separation. Linearity varied from 2 to 4800 ng/mL and the use of 13C2-labeled derivatives allowed for the correction of matrix effects as well as the unambiguous confirmation of the identity of each metabolite in the presence of interfering isomers in urine. Despite the challenges associated with method validation, the method was fully validated as per the food and drug administration (FDA) and the European medicines agency (EMA) recommendations. Validation criteria included linearity, precision, accuracy, dilution integrity, selectivity, carryover, and stability. Challenges in selectivity experiments included the isotopic contributions of the analyte towards its internal standard (IS), that was addressed via the optimization of the IS concentration. In addition, incurred sample analysis was performed to ensure that results from patient samples are accurate and reliable. The method was robust and reproducible and is currently being applied in a cohort of asthma and COPD patient urine samples for biomarker discovery purposes.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.007
      Issue No: Vol. 989 (2017)
       
  • Derivatization enhanced separation and sensitivity of long chain-free
           fatty acids: Application to asthma using targeted and non-targeted liquid
           chromatography-mass spectrometry approach
    • Authors: Xiqing Bian; Baoqing Sun; Peiyan Zheng; Na Li; Jian-Lin Wu
      Pages: 59 - 70
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Xiqing Bian, Baoqing Sun, Peiyan Zheng, Na Li, Jian-Lin Wu
      Long chain-free fatty acids (LCFFAs) play pivotal roles in various physiological functions, like inflammation, insulin resistance, hypertension, immune cell behavior and other biological activities. However, the detection is obstructed by the low contents, structural diversity, high structural similarity, and matrix interference. Herein, a fast cholamine-derivatization, within 1 min at room temperature, coupled with liquid chromatography-mass spectrometry (LC-MS) approach was developed to determine LCFFAs in complex samples. After derivatization, the ionization and separation efficiency were significantly improved, which resulted in up to 2000-fold increase of sensitivity compared with non-derivatization method, and the limits of detection were at low femtogram level. As well, this approach was applied successfully in the rapid profiling or quantification of targeted and non-targeted LCFFAs in the sera of healthy human and asthma patients. The targeted metabolomics method showed that the contents of 17 PUFAs were significantly changed in asthma patients, especially hydroxyeicosatetraenoic acids (HETEs), hydroperoxyeicosatetraenoic acid (HPETEs) and prostaglandins (PGs). The non-targeted method resulted in the tentatively identification of 35 LCFFAs including 31 saturated and mono-unsaturated LCFFAs, and 4 bile acids, except for 27 poly-unsaturated fatty acids (PUFAs), and the multivariate analysis indicated that eicosapentaenoic acid (EPA), ursodeoxycholic acid, deoxycholic acid, isodeoxycholic acid, palmitic acid, 2-lauroleic acid and lauric acid also have significant difference between healthy and asthma groups except for 17 PUFAs. To the best of our knowledge, this is the first report on the relationship of asthma with 5(S)-, 15(S)-HPETE, 8(S)-, 11(S)-HETE, 15(S)-HEPE, PGA2, PGB2, PGE1, PGF1α, PGJ2, and 13, 14-dehydro-15-keto PGF2α (DK-PGF2α).
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.009
      Issue No: Vol. 989 (2017)
       
  • A novel substrate-inspired fluorescent probe to monitor native albumin in
           human plasma and living cells
    • Authors: Guang-Bo Ge; Lei Feng; Qiang Jin; Yi-Ru Wang; Zhao-Ming Liu; Xin-Yue Zhu; Ping Wang; Jie Hou; Jing-Nan Cui; Ling Yang
      Pages: 71 - 79
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Guang-Bo Ge, Lei Feng, Qiang Jin, Yi-Ru Wang, Zhao-Ming Liu, Xin-Yue Zhu, Ping Wang, Jie Hou, Jing-Nan Cui, Ling Yang
      Human albumin (HA) displays crucial roles in maintaining health and fighting diseases. Accurate determination of native HA in plasma or non-plasma samples are of immense significance in both basic research and clinical practice. Herein, a novel ratiometric two-photon fluorescent probe (N-butyl-4-(4-phenyl-benzoyloxy) 1,8-naphthalimide, BPBN) has been designed and developed for highly selective and sensitive sensing the enzymatic activities of HA, on the basis of its unique pseudo-esterase feature. BPBN exhibits excellent selectivity, high sensitivity and good reactivity under physiological conditions. As an enzymatic activity-based probe, BPBN can distinguish between native HA and denatured HA, while the currently used dye-binding method cannot. The probe has been successfully applied to measure native HA in plasma samples and the secreted HA in the hepatocyte culture supernatant. BPBN has also been used for two-photon imaging of HA reabsorption in living renal cells, and the results demonstrate that this probe exhibits good cell permeability, low cytotoxicity and high imaging resolution. All these findings suggest that BPBN can be reliably used for the highly selective and sensitive detection of native HA in complex biological samples, as well as for exploring HA-associated biological processes and the physiological functions of native HA in living cells.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.048
      Issue No: Vol. 989 (2017)
       
  • Potentiometric sensor for non invasive lactate determination in human
           sweat
    • Authors: Massimo Onor; Stefano Gufoni; Tommaso Lomonaco; Silvia Ghimenti; Pietro Salvo; Fiodor Sorrentino; Emilia Bramanti
      Pages: 80 - 87
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Massimo Onor, Stefano Gufoni, Tommaso Lomonaco, Silvia Ghimenti, Pietro Salvo, Fiodor Sorrentino, Emilia Bramanti
      The present work describes a non invasive lactate sensing in sweat during workout. The sensing system is based on a non-equilibrium potentiometric measure performed using disposable, chemically modified, screen printed carbon electrodes (SPCEs) that can be wetted with sweat during the exercise. The potentiometric signal, which is proportional to lactate concentration in sweat, is produced by a redox reaction activated by UV radiation, as opposed to the enzymatic reaction employed in traditional, blood-based measuring devices. The sensing system exhibits chemical selectivity toward lactate with linearity from 1 mM up to 180 mM. The dynamic linear range is suitable for measurement of lactate in sweat, which is more than 10 times concentrated than hematic lactate and reaches more than 100 mM in sweat during workout. The noninvasive measure can be repeated many times during exercise and during the recovery time in order to get personal information on the physiological and training status as well as on the physical performance. The device was successfully applied to several human subjects for the measurement of sweat lactate during prolonged cycling exercise. During the exercise sweat was simultaneously sampled on filter paper and extracted in water, and the lactate was determined by HPLC for method validation. The lactate concentration changes during the exercise reflected the intensity of physical effort. This method has perspectives in many sport disciplines as well as in health care and biomedical area.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.050
      Issue No: Vol. 989 (2017)
       
  • A hydrogen peroxide sensor based on TNM functionalized reduced graphene
           oxide grafted with highly monodisperse Pd nanoparticles
    • Authors: Sait Bozkurt; Berna Tosun; Betül Sen; Süleyman Akocak; Aysun Savk; Mehmet Faruk Ebeoğlugil; Fatih Sen
      Pages: 88 - 94
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Sait Bozkurt, Berna Tosun, Betül Sen, Süleyman Akocak, Aysun Savk, Mehmet Faruk Ebeoğlugil, Fatih Sen
      Addressed herein, we report the synthesis and characterization of a tert-nonyl mercaptan (TNM) functionalized reduced graphene oxide (rGO) supported palladium (Pd) nanoparticles (NPs) (Pd/TNM@rGO) as electrochemical sensor. The highly monodisperse Pd/TNM@rGO nanocomposite was applied for electrochemical determination of hydrogen peroxide (H2O2) at a potential range of −0.6 to +0.8 V. The Pd/TNM@rGO sensor demonstrated very high activity, sensitivity, reusability and durability toward H2O2 sensing. The well dispersed Pd/TNM@rGO nanocomposite has been characterized by using several analytical techniques such as, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and electrochemical impedance spectroscopy (EIS). The catalytic performance of prepared biosensor was also characterized by using cyclic voltammetry (CV) and chronoamperometry (CA) methods. The proposed H2O2 biosensor showed a broad linear range up to 12 mM, and a very low detection limit of 0.0025 μM, with a quick response time of less than 10 s. Additionally, the biosensor exhibited great capability, reproducibility and durability for the examination of H2O2.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.051
      Issue No: Vol. 989 (2017)
       
  • Immunosensor array platforms based on self-assembled dithiols for the
           electrochemical detection of tetrodotoxins in puffer fish
    • Authors: Laia Reverté; Katrina Campbell; Maria Rambla-Alegre; Christopher T. Elliott; Jorge Diogène; Mònica Campàs
      Pages: 95 - 103
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Laia Reverté, Katrina Campbell, Maria Rambla-Alegre, Christopher T. Elliott, Jorge Diogène, Mònica Campàs
      The recent detection of tetrodotoxins (TTXs) in European fish and shellfish has emphasized the urgent need to develop specific, selective, rapid and easy-to-use methods for their detection to assess the potential risk posed to human health. For this purpose, a dithiol self-assembled monolayer (SAM)-based immunoassay previously performed on maleimide plates (mELISA) has been adapted to gold electrode arrays for the development of an electrochemical immunosensor for TTX. The electrochemical SAM-based immunosensor designed herein, provided an oriented, stable and spaced sensing platform for the determination of TTX, attaining a limit of detection of 2.6 ng mL−1. The applicability of the biosensor array was demonstrated by the accurate quantifications obtained in the analysis of different tissues of several puffer fish species (Lagocephalus lagocephalus, L. sceleratus and Sphoeroides pachygaster) caught along the Mediterranean coast of Spain. The good agreements found between the TTX concentrations determined by the immunosensor array platforms and those determined by mELISA, surface Plasmon resonance (SPR) immunosensor and liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis, proved the feasibility of the approach. The electrochemical immunosensor enables the determination of TTXs at levels as low as 0.07 mg TTX equiv. kg−1 tissue, thus, well below the Japanese value of 2 mg TTX equiv. kg−1 tissue used as a criterion to consider puffer fish safe for consumption. Compared to the colorimetric SAM-based approach, the immunosensor array described herein shows promise towards the development of disposable, portable and compact analysis tools applicable in monitoring programs for the surveillance of fishery products.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.052
      Issue No: Vol. 989 (2017)
       
  • High sensitivity and selectivity in quantitative analysis of drugs in
           biological samples using 4-column multidimensional micro-UHPLC-MS enabling
           enhanced sample loading capacity
    • Authors: Ronald de Vries; Liesbeth Vereyken; Isabelle François; Lieve Dillen; Rob J. Vreeken; Filip Cuyckens
      Pages: 104 - 111
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Ronald de Vries, Liesbeth Vereyken, Isabelle François, Lieve Dillen, Rob J. Vreeken, Filip Cuyckens
      Sensitivity is often a critical parameter in quantitative bioanalyses in drug development. For liquid-chromatography-based methods, sensitivity can be improved by reducing the column diameter, but practical sensitivity gains are limited by the reduced sample loading capacity on small internal diameter (I.D.) columns. We developed a set-up that has overcome these limitations in sample loading capacity. The set-up uses 4 columns with gradually decreasing column diameters along the flow-path (2.1 → 1 → 0.5 → 0.15 mm). Samples are pre-concentrated on-line on a 2.1 mm I.D. trapping column and back flushed to a 1 mm I.D. UHPLC analytical column and separated. The peak(s) of interest are transferred using heartcutting to a second trapping column (0.5 mm I.D.), which is back-flushed to a 0.15 mm I.D. micro-UHPLC analytical column for orthogonal separation. The proof of concept of the set-up was demonstrated by the simultaneous analysis of midazolam and 1′-hydroxy midazolam in plasma by injection of 80 μL of protein precipitated plasma. The 4-column funnel set-up proved to be robust and resulted in a 10–50 times better sensitivity compared to a trap-elute approach and 250–500 fold better compared to direct micro-UHPLC analysis. A lower limit of quantification of 100 fg/mL in plasma was obtained for both probe compounds.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.067
      Issue No: Vol. 989 (2017)
       
  • Ultra-high performance supercritical fluid chromatography-mass
           spectrometry procedure for analysis of monosaccharides from plant gum
           binders
    • Authors: Volodymyr Pauk; Tomáš Pluháček; Vladimír Havlíček; Karel Lemr
      Pages: 112 - 120
      Abstract: Publication date: 9 October 2017
      Source:Analytica Chimica Acta, Volume 989
      Author(s): Volodymyr Pauk, Tomáš Pluháček, Vladimír Havlíček, Karel Lemr
      The ultra-high performance supercritical fluid chromatography-mass spectrometry (UHPSFC/MS) procedure for analysis of native monosaccharides was developed. Chromatographic conditions were investigated to separate a mixture of four hexoses, three pentoses, two deoxyhexoses and two uronic acids. Increasing water content in methanol modifier to 5% and formic acid to 4% improved peak shapes of neutral monosaccharides and allowed complete elution of highly polar uronic acids in a single run. An Acquity HSS C18SB column outperformed other three tested stationary phases (BEH (silica), BEH 2-ethylpyridine, CSH Fluoro-Phenyl) in terms of separation of isomers and analysis time (4.5 min). Limits of detection were in the range 0.01–0.12 ng μL−1. Owing to separation of anomers, identification of critical pairs (arabinose-xylose and glucose-galactose) was possible. Feasibility of the new method was demonstrated on plant-derived polysaccharide binders. Samples of watercolor paints, painted paper and three plant gums widely encountered in painting media (Arabic, cherry and tragacanth) were decomposed prior the analysis by microwave-assisted hydrolysis at 40 bar initial pressure using 2 mol L−1 trifluoroacetic acid. Among tested temperatures, 120 °C ensured appropriate hydrolysis efficiency for different types of gum and avoided excessive degradation of labile monosaccharides. Procedure recovery tested on gum Arabic was 101% with an RSD below 8%. Aqueous hydrolysates containing monosaccharides in different ratios specific to each type of plant gum were diluted or analyzed directly. Filtration of samples before hydrolysis reduced interferences from a paper support and identification of gum Arabic in watercolor-painted paper samples was demonstrated. Successful identification of pure gum Arabic was confirmed for sample quantities as little as 1 μg. Two classification approaches were compared and principal component analysis was superior to analysis based on peak area ratios of monosaccharides. The proposed procedure using UHPSFC/MS represents an interesting alternative which can compete with other chromatographic methods in the field of saccharide analysis in terms of speed, sensitivity and simplicity of workflow.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.036
      Issue No: Vol. 989 (2017)
       
  • Review: Novel sensing strategies for bacterial detection based on active
           and passive methods driven by external field
    • Authors: Shiho Tokonami; Takuya Iida
      Pages: 1 - 16
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Shiho Tokonami, Takuya Iida
      For sustainable human life, biosensing systems for contaminants or disease-causing bacteria are crucial for food security, environmental improvement, and disease prevention. With an aim of enhancing the sensitivity and detection speed, many researchers have developed efficient detection methods for target bacteria. In this review, we discuss recent topics related to active and passive bacterial detection methods, including (1) optical approaches with unique functional nano- and micro-structures, and (2) electrical approaches involving mechanical modulation and electrochemical reactions. Particularly, we discuss the prospects in the development of label-free, rapid, and highly sensitive biosensors based on active detection principles with light-induced dynamics, in conjunction with dielectrophoresis-induced selective trapping.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.034
      Issue No: Vol. 988 (2017)
       
  • A modified DGT technique for the simultaneous measurement of dissolved
           inorganic nitrogen and phosphorus in freshwaters
    • Authors: Jianyin Huang; William W. Bennett; Peter R. Teasdale; Nadeeka Rathnayake Kankanamge; David T. Welsh
      Pages: 17 - 26
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Jianyin Huang, William W. Bennett, Peter R. Teasdale, Nadeeka Rathnayake Kankanamge, David T. Welsh
      A modified diffusive gradients in thin films (DGT) technique uses both a mixed binding layer (PrCH and A520E resins for NH4-N and NO3-N, respectively) and multiple binding layers (Metsorb binding layer for PO4-P overlying the mixed binding layer) for the simultaneous measurement of dissolved inorganic nitrogen (nitrate and ammonium) and phosphate in freshwater (INP-DGT). High uptake and elution efficiencies were determined for a mixed (PrCH/A520E) binding gel for dissolved inorganic nitrogen and an agarose-based Metsorb binding layer for PO4-P. Diffusion coefficients (D) obtained from DGT time-series experiments (conductivity 180 μS cm−1) for NH4-N, NO3-N and PO4-P agreed well with those measured using individual DGT techniques in previous studies, but were characterised over a wider range of ionic strengths here. D for NO3-N and PO4-P were constant over a range of ionic strengths (between 100 and 800 μS cm−1) while the diffusion coefficient for NH4-N decreased with increasing ionic strength, as reported previously. The measurement of NH4-N, NO3-N and PO4-P using the INP-DGT was independent of pH (3.5–8.5) and quantitative over varying ionic strength ranges (up to 0.004 mol L−1 NaCl for NH4-N, up to 0.014 mol L−1 NaCl for NO3-N and over 0.1 mol L−1 NaCl for PO4-P) for a 24 h deployment time. Performance of INP-DGT in synthetic freshwaters with differing conductivity indicated the three nutrients were affected differently, with NH4-N measurements being most sensitive. Representative performance was determined for NO3-N (90–330 μS cm−1) and PO4-P (all tested conductivities) over a 72 h deployment period and for NH4-N (<330 μS cm−1) over a 24 h deployment period. Field validations showed that the ratios of INP-DGT concentrations to the average concentrations from grab samples were generally between 0.80 and 1.13 over 24 and 48 h deployment periods. To ensure the representative performance of INP-DGT for all three nutrients, the conductivity should not exceed 400 μS cm−1 and deployment times should be no longer than 24 h. The results of this study have demonstrated that INP-DGT could provide a cost-effective monitoring technique for measuring time-weighted average concentrations of dissolved inorganic nutrients in many freshwaters.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.024
      Issue No: Vol. 988 (2017)
       
  • Improving wastewater-based epidemiology to estimate cannabis use: focus on
           the initial aspects of the analytical procedure
    • Authors: Ana Causanilles; Jose Antonio Baz-Lomba; Daniel A. Burgard; Erik Emke; Iria González-Mariño; Ivona Krizman-Matasic; Angela Li; Arndís S.C. Löve; Ann Kathrin McCall; Rosa Montes; Alexander L.N. van Nuijs; Christoph Ort; José B. Quintana; Ivan Senta; Senka Terzic; Félix Hernandez; Pim de Voogt; Lubertus Bijlsma
      Pages: 27 - 33
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Ana Causanilles, Jose Antonio Baz-Lomba, Daniel A. Burgard, Erik Emke, Iria González-Mariño, Ivona Krizman-Matasic, Angela Li, Arndís S.C. Löve, Ann Kathrin McCall, Rosa Montes, Alexander L.N. van Nuijs, Christoph Ort, José B. Quintana, Ivan Senta, Senka Terzic, Félix Hernandez, Pim de Voogt, Lubertus Bijlsma
      Wastewater-based epidemiology is a promising and complementary tool for estimating drug use by the general population, based on the quantitative analysis of specific human metabolites of illicit drugs in urban wastewater. Cannabis is the most commonly used illicit drug and of high interest for epidemiologists. However, the inclusion of its main human urinary metabolite 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) in wastewater-based epidemiology has presented several challenges and concentrations seem to depend heavily on environmental factors, sample preparation and analyses, commonly resulting in an underestimation. The aim of the present study is to investigate, identify and diminish the source of bias when analysing THC-COOH in wastewater. Several experiments were performed to individually assess different aspects of THC-COOH determination in wastewater, such as the number of freeze-thaw cycles, filtration, sorption to different container materials and in-sample stability, and the most suitable order of preparatory steps. Results highlighted the filtration step and adjustment of the sample pH as the most critical parameters to take into account when analysing THC-COOH in wastewater. Furthermore, the order of these initial steps of the analytical procedure is crucial. Findings were translated into a recommended best-practice protocol and an inter-laboratory study was organized with eight laboratories that tested the performance of the proposed procedure. Results were found satisfactory with z-scores ≤ 2.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.011
      Issue No: Vol. 988 (2017)
       
  • Improved analytical techniques of sulfur isotopic composition in nanomole
           quantities by MC-ICP-MS
    • Authors: Tsai-Luen Yu; Bo-Shian Wang; Chuan-Chou Shen; Pei-Ling Wang; Tsanyao Frank Yang; George S. Burr; Yue-Gau Chen
      Pages: 34 - 40
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Tsai-Luen Yu, Bo-Shian Wang, Chuan-Chou Shen, Pei-Ling Wang, Tsanyao Frank Yang, George S. Burr, Yue-Gau Chen
      We propose an improved method for precise sulfur isotopic measurements by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in conjunction with a membrane desolvation nebulization system. The problems of sulfur loss through the membrane desolvation apparatus are carefully quantified and resolved. The method overcomes low intrinsic sulfur transmission through the instrument, which was initially 1% when operating at a desolvation temperature of 160 °C. Sulfur loss through the membrane desolvation apparatus was resolved by doping with sodium. A Na/S ratio of 2 mol mol−1 produced sulfur transmissions with 98% recovery. Samples of 3 nmol (100 ng) sulfur achieved an external precision of ±0.18‰ (2 SD) for δ34S and ±0.10‰ (2 SD) for Δ33S (uppercase delta expresses the extent of mass-independent isotopic fractionation). Measurements made on certified reference materials and in-house standards demonstrate analytical accuracy and reproducibility. We applied the method to examine microbial-induced sulfur transformation in marine sediment pore waters from the sulfate-methane transition zone. The technique is quite versatile, and can be applied to a range of materials, including natural waters and minerals.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.012
      Issue No: Vol. 988 (2017)
       
  • Identification of novel non-ionic, cationic, zwitterionic, and anionic
           polyfluoroalkyl substances using UPLC–TOF–MSE high-resolution parent
           ion search
    • Authors: Feng Xiao; Svetlana A. Golovko; Mikhail Y. Golovko
      Pages: 41 - 49
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Feng Xiao, Svetlana A. Golovko, Mikhail Y. Golovko
      Poly- and perfluoroalkyl substances (poly- and per-PFASs) are a large group of organic compounds that have become the target of investigation due to their widespread occurrence in the environment and biota, coupled with their known or suspected impacts on human health. Recent studies have shown that a significant portion of poly-PFASs remain unidentified. This study presents a time-of-flight mass spectrometry approach based on continuously interleaving scans at low and high collision energies (ToF-MSE) for the rapid identification and characterization of unknown PFASs. The MSE mode allowed for the simultaneous acquisition of full-spectrum accurate mass data of both parent and fragment ions in a single chromatographic run. Specific to PFASs, the hypothesis that PFASs can be selectively detected by the ToF–MSE high-resolution parent-ion search (HRPIS) of their characteristic fragments was confirmed with certified standards of 24 poly- and per-PFAS. After being validated with these certified standards, the innovative HRPIS approach was applied to a group of commercial surfactants, which led to the identification of 47 new and 43 infrequently reported PFASs, including 40 non-ionic, 30 cationic, 15 zwitterionic, and five anionic compounds. It is envisaged that the results, especially the identification of new non-ionic PFASs, may provide important insights into the historical occupational and non-occupational exposure to PFASs from the production and application of these surfactants.
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      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.016
      Issue No: Vol. 988 (2017)
       
  • Controlled, synchronized actuation of microdroplets by gravity in a
           superhydrophobic, 3D-printed device
    • Authors: P.E. Oomen; J.P.S.H. Mulder; E. Verpoorte; R.D. Oleschuk
      Pages: 50 - 57
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): P.E. Oomen, J.P.S.H. Mulder, E. Verpoorte, R.D. Oleschuk
      Droplet manipulation over open surfaces allows one to perform assays with a large degree of control and high throughput, making them appealing for applications in drug screening or (bio)analysis. However, the design, manufacturing and operation of these systems comes with high technical requirements. In this study we employ a commercial, low-friction, superhydrophobic coating, Ultra-Ever Dry®, on a 3D-printed microfluidic device. The device features individual droplet compartments, which allow the manipulation of discrete droplets (10–50 μL) actuated by gravity alone. Simply by angling the device to normal in a 3D-printed holder and rocking in a “to and fro”-fashion, a sequence of droplets can be individually transferred to an electrochemical microelectrode detector and then to waste, while preserving the (chronological) order of samples. Multiple biological fluids (i.e. human saliva, urine and rat blood and serum) were successfully tested for compatibility with the device and actuation mechanism, demonstrating low slip angles and high contact angles. Biological matrix (protein) carryover was probed and effectively mitigated by incorporating aqueous rinse droplets as part of the analysis sequence. As a proof-of-concept, the enzyme-coupled, amperometric detection of glucose was carried out on individual rat serum droplets, enabling total analysis in ≈30 min, including calibration. The device is readily customizable, and the integration of droplet generation techniques and other sensor systems for different analytes of interest or applications can be realized in a plug and play fashion.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.010
      Issue No: Vol. 988 (2017)
       
  • Highly selective and sensitive visualization and identification of
           glycoproteins using multi-functionalized soluble dendrimer
    • Authors: Tiantian Li; Zhenlong Yu; Liyuan Zhang; Chao Wang; Sa Deng; Xiaokui Huo; Xiangge Tian; Baojing Zhang; Xiaochi Ma
      Pages: 58 - 65
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Tiantian Li, Zhenlong Yu, Liyuan Zhang, Chao Wang, Sa Deng, Xiaokui Huo, Xiangge Tian, Baojing Zhang, Xiaochi Ma
      Glycoproteins are the most important and complex group of posttranslational modifications known in proteins. Many clinical biomarkers and therapeutic targets in cancer are glycoproteins. However, the isolation of glyco-specific antibodies and their poor stability remains a significant challenge in analytical method and diagnostic development. In this work, for the first time, we present a technology for highly efficient and selective glycosylation analysis on membrane without the use of glyco-specific antibodies. This approach, termed Nanopoly-BAV, which uses polyamidoamine dendrimers multifunctionalized with boronic acid for specific binding to glycoproteins and with biotin groups for glycoproteins visualization. The Nanopoly-BAV confers femtomolar sensitivity, exceptional glycoprotein specificity and selectivity with as high as 100000 folds for glycoproteins over nonglycoproteins. This synthetic, robust and highly selective Nanopoly-BAV has a great potential to measure cell signaling events by clearly distinguishing actual glycosylation signals from protein expression changes with superior stability. This technique may provide a powerful tool to monitor cellular signaling pathways and discovering new signaling events.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.053
      Issue No: Vol. 988 (2017)
       
  • Selective imaging of cancer cells with a pH-activatable lysosome-targeting
           fluorescent probe
    • Authors: Rongguang Shi; Lu Huang; Xiaoxue Duan; Guohao Sun; Gui Yin; Ruiyong Wang; Jun-jie Zhu
      Pages: 66 - 73
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Rongguang Shi, Lu Huang, Xiaoxue Duan, Guohao Sun, Gui Yin, Ruiyong Wang, Jun-jie Zhu
      Fluorescence imaging with tumor-specific fluorescent probe has emerged as a tool to aid surgeons in the identification and removal of tumor tissue. We report here a new lysosome-targeting fluorescent probe (NBOH) with BODIPY fluorephore to distinguish tumor tissue out of normal tissue based on different pH environment. The probe exhibited remarkable pH-dependent fluorescence behavior in a wide pH range from 3.0 to 11.0, especially a sensitive pH-dependent fluorescence change at pH range between 3.5 and 5.5, corresponding well to the acidic microenvironment of tumor cells, in aqueous solution. The response time of NBOH was extremely short and the photostability was proved to be good. Toxicity test and fluorescence cell imaging together with a sub-cellular localization study were carried out revealing its low biotoxicity and good cell membrane permeability. And NBOH was successfully applied to the imaging of tumor tissue in tumor-bearing mice suggesting potential application to surgery as a tumor-specific probe.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.055
      Issue No: Vol. 988 (2017)
       
  • Silver nanoclusters capped silica nanoparticles as a ratiometric
           photoluminescence nanosensor for the selective detection of I− and S2−
           
    • Authors: Xinan Huang; Sohail Anjum Shahzad; Yongxin Li; Yunyi Zhang; Lijia Sang; Huipeng Zhou; Hong Jiang; Kenneth Kam-Wing Lo; Cong Yu
      Pages: 74 - 80
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Xinan Huang, Sohail Anjum Shahzad, Yongxin Li, Yunyi Zhang, Lijia Sang, Huipeng Zhou, Hong Jiang, Kenneth Kam-Wing Lo, Cong Yu
      A novel and efficient approach has been established for the synthesis of silver nanoclusters capped silica nanoparticles (SiO2@AgNCs). These nanoclusters (AgNCs) capped silica nanoparticles were utilized as a novel ratiometric photoluminescence (PL) nanosensor for extremely sensitive and selective detection of I− and S2− ions. The AgNCs were prepared in situ on the silica nanoparticles through polyethyleneimine (PEI) template approach. While dual PL emissions of AgNCs (at 500 nm) and luminescent silica nanoparticles (at 602 nm) formed the basis for the ratiometric sensing. The PL emission of AgNCs was strongly quenched by I− (or S2−), while that of luminescent silica nanoparticles was hardly affected. The PL emission intensity ratio of AgNCs and the luminescent silica nanoparticles was defined as I500/I602. A good linear relationship between the I500/I602 value and the concentration of I− (or S2−) was observed, and the limit of detection (LOD) was estimated to be 57 nM for I− and 62 nM for S2−. In addition, the fluorescence images of the SiO2@AgNCs nanosensor changed from white to orange upon exposure to different concentrations of I− (or S2−) (0–250 μM), which could be clearly distinguished by the naked eye. The SiO2@AgNCs nanosensor exhibited good selectivity against other analytes, and I− or S2− ions could be separately detected via the introduction of proper masking agents. Furthermore, the detection of I− and S2− in real water samples was also demonstrated.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.056
      Issue No: Vol. 988 (2017)
       
  • Genetically functionalized ferritin nanoparticles with a high-affinity
           protein binder for immunoassay and imaging
    • Authors: Jong-won Kim; Woosung Heu; Sukyo Jeong; Hak-Sung Kim
      Pages: 81 - 88
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Jong-won Kim, Woosung Heu, Sukyo Jeong, Hak-Sung Kim
      Molecular detection of target molecules with high sensitivity and specificity is of great significance in bio and medical sciences. Here, we present genetically functionalized ferritin nanoparticles with a high-affinity protein binder, and their utility as a signal generator in a variety of immunoassays and imaging. As a high-affinity protein binder, human IgG-specific repebody, which is composed of LRR (Leucine-rich repeat) modules, was used. The repebody was genetically fused to the N-terminal heavy-chain ferritin, and the resulting subunits were self-assembled to the repebody-ferritin nanoparticles composed of 24 subunits. The repebody-ferritin nanoparticles were shown to have a three-order of magnitude higher binding affinity toward human IgG than free repebody mainly owing to a decreased dissociation rate constant. The repebody-ferritin nanoparticles were conjugated with fluorescent dyes, and the resulting nanoparticles were used for western blotting, cell imaging, and flow cytometric analysis. The dye-labeled repebody-ferritin nanoparticles were shown to generate about 3-fold stronger fluorescent signals in immunoassays than monovalent repebody. The repebody-functionalized ferritin nanoparticles can be effectively used for sensitive and specific immunoassays and imaging in many areas.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.060
      Issue No: Vol. 988 (2017)
       
  • A Eu(III) doped metal-organic framework conjugated with
           fluorescein-labeled single-stranded DNA for detection of Cu(II) and
           sulfide
    • Authors: Han Weng; Bing Yan
      Pages: 89 - 95
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Han Weng, Bing Yan
      In this paper, Bio-MOF-1 is prepared as reported and then Eu3+ is introduced into it via cation exchange method. A FAM-labeled ssDNA is chosen to fabricate with the obtained Eu3+@Bio-MOF-1. A luminescent hybrid material is assembled, which can exhibit the fluorescence of Eu3+ and FAM simultaneously by adjusting the ratio of FAM-ssDNA and Eu3+@Bio-MOF-1. The sample is then used for the detecting of metal ions, results shows which has good selectively for Cu2+ (LOD = 0.14 μM, 0–250 μM). The introduction of Cu2+ can quench the fluorescence of FAM while the luminescent intensity of Eu3+ enhancing. After the detection of Cu2+, the Cu2+ involved hybrid system can then be further employed for the detection of S2− (LOD = 1.3 μM, 0–50 μM). Low concentration of S2− can make the luminescent intensity of Eu3+ decrease gradually while high concentration of S2− can further recover the luminescent of FAM, which is quenched by Cu2+.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.061
      Issue No: Vol. 988 (2017)
       
  • Systematic approach in Mg2+ ions analysis with a combination of tailored
           fluorophore design
    • Authors: L. Lvova; C. Guanais Gonçalves; L. Prodi; M. Sgarzi; N. Zaccheroni; M. Lombardo; A. Legin; C. Di Natale; R. Paolesse
      Pages: 96 - 103
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): L. Lvova, C. Guanais Gonçalves, L. Prodi, M. Sgarzi, N. Zaccheroni, M. Lombardo, A. Legin, C. Di Natale, R. Paolesse
      A systematic study of a series of diaza-18-crown-6 8-hydroxyquinoline (DCHQ) chemosensors, devoted to Mg(II) ion detection, was performed. Functionalization of DCHQ by peripheral substituents allowed the development of novel all-solid-state optodes via inclusion inside PVC-based polymeric films. The influence on the DCHQ-based optode response of the lipophilic sites functionalization and of the nature of the plasticizer, was investigated. Fluorimetric studies on optodes sensitivity towards a number of different metal cations (Ca2+, Na+, K+, Li+, Co2+, Cd2+, Pb2+, Cu2+, Hg2+, Zn2+) and NH4 + were carried out. The results demonstrated the suitability of the DCHQ optodes to perform fast monitoring (<10s) of magnesium (II) ions. Emission light signal was sufficiently brilliant to be captured by a low-cost computer webcam. The phenyl-substituted DCHQ-Ph derivative showed the best performance with a wide range for Mg(II) ion determination between 2.7 × 10−7 and 2.2 × 10−2 mol/L. It was possible, therefore, to determine the concentrations of Mg(II) in commercial fertilizer samples by DCHQ-Ph–based optodes with acceptable results: recoveries of 96.2–104.9% and relative standard deviation (RSD, n = 6) less than 5%. Moreover, in comparison to single sensors, the use of an array composed of five optodes (the ones showing the best performances in the preliminary tests) has allowed to reduce the RSD of magnesium determination in real samples (down to 3.7% with respect to 5.5% for single optodes) and to achieve a detection limit (estimated by s/n = 3 method) as low as 4.6 × 10−7 mol/L.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.07.062
      Issue No: Vol. 988 (2017)
       
  • The preparation of a poly (pentaerythritol tetraglycidyl ether-co-poly
           ethylene imine) organic monolithic capillary column and its application in
           hydrophilic interaction chromatography for polar molecules
    • Authors: Ye Chen; Yan Shu; Zihui Yang; Xumei Lv; Wangming Tan; Yingzhuang Chen; Ming Ma; Bo Chen
      Pages: 104 - 113
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Ye Chen, Yan Shu, Zihui Yang, Xumei Lv, Wangming Tan, Yingzhuang Chen, Ming Ma, Bo Chen
      An easy single-step thermal treatment “one-pot” approach for the preparation of poly (pentaerythritol tetraglycidyl ether-co-poly ethylene imine) organic monolithic capillary columns was developed successfully. The column was prepared by the epoxy-amine ring-opening polymerization of pentaerythritol tetraglycidyl ether (PTE) with poly (ethylene imine) (PEI) using acetonitrile (ACN) and polyethylene glycol 600 (PEG 600) as the porogenic system at 60 °C for 12 h. The obtained monolith was homogeneous and permeable. It achieved the high-efficiency separation of polar molecules including amides, nucleosides, bases, phenols, and benzoic acids in capillary liquid chromatography (cLC). The highest column efficiency reached ca. 101,000 plates/m (for guanine) on monolith poly(PTE-co-PEI) at 0.64 mm/s, and satisfactory chromatographic performance with column efficiencies ranged from 45,500 to 97,000 plates/m was achieved for the four amides. A typical hydrophilic interaction liquid chromatography (HILIC) retention mechanism was observed with high organic solvent contents (>60% ACN). Also, the polymer-based monolithic column was successfully applied to separate the tumor markers. Furthermore, the poly(PTE-co-PEI) monolith could be easily modified with 1, 2-epoxydodecane, which reacted with the amino groups presented on the surface of the poly(PTE-co-PEI) monolith. Hydrophobic interactions were observed during the separation of alkylbenzenes and anilines on the post-modified poly(PTE-co-PEI) monolith. Together, these results confirm the feasibility of the epoxy-amine ring-opening polymerization reaction during the fabrication of a monolithic column with high efficiency for cLC applications.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.025
      Issue No: Vol. 988 (2017)
       
  • Determination of 99Tc in fresh water using TRU resin by ICP-MS
    • Authors: Nicolas Guérin; Remi Riopel; Sheila Kramer-Tremblay; Nimal de Silva; Jack Cornett; Xiongxin Dai
      Pages: 114 - 120
      Abstract: Publication date: 2 October 2017
      Source:Analytica Chimica Acta, Volume 988
      Author(s): Nicolas Guérin, Remi Riopel, Sheila Kramer-Tremblay, Nimal de Silva, Jack Cornett, Xiongxin Dai
      Technetium-99 (99Tc) determination at trace level by inductively coupled plasma mass spectrometry (ICP-MS) is challenging because there is no readily available appropriate Tc isotopic tracer. A new method using Re as a recovery tracer to determine 99Tc in fresh water samples, which does not require any evaporation step, was developed. Tc(VII) and Re(VII) were pre-concentrated on a small anion exchange resin (AER) cartridge from one litre of water sample. They were then efficiently eluted from the AER using a potassium permanganate (KMnO4) solution. After the reduction of KMnO4 in 2 M sulfuric acid solution, the sample was passed through a small TRU resin cartridge. Tc(VII) and Re(VII) retained on the TRU resin were eluted using near boiling water, which can be directly used for the ICP-MS measurement. The results for method optimisation, validation and application were reported.
      Graphical abstract image

      PubDate: 2017-09-18T04:53:38Z
      DOI: 10.1016/j.aca.2017.08.013
      Issue No: Vol. 988 (2017)
       
  • Outside front cover
    • Abstract: Publication date: 16 October 2017
      Source:Analytica Chimica Acta, Volume 990


      PubDate: 2017-10-14T11:19:30Z
       
  • RElative QUantitation Inferred by Evaluating Mixtures (REQUIEM)
    • Authors: Sami T. Tuomivaara; Paul Schliekelman; Alison V. Nairn; Kelley W. Moremen; William S. York
      Abstract: Publication date: Available online 4 October 2017
      Source:Analytica Chimica Acta
      Author(s): Sami T. Tuomivaara, Paul Schliekelman, Alison V. Nairn, Kelley W. Moremen, William S. York
      Motivated by the lack of easily implementable and generally applicable strategies to increase and assess data accuracy, we devised a novel label-free approach, termed REQUIEM, to address challenges in relative quantitation. For comparing the relative amounts of analytes in two samples, a mixture is prepared from aliquots of the samples, and the samples and the mixture are analyzed in parallel according to the intended workflow. Processing of the resulting data using the REQUIEM algorithm yields unbiased analyte fold-changes and associated statistics, allowing several types of errors to be diagnosed or eliminated. Extensive simulations and analysis of carefully prepared standard samples demonstrated the rigorous foundations of REQUIEM. We applied REQUIEM to several real-world analytical techniques and workflows, notably to tandem mass spectrometry analysis by using isomeric oligosaccharides as test analytes. We conclude that REQUIEM can reveal inaccuracies in the data that are difficult to identify by using traditional approaches.
      Graphical abstract image

      PubDate: 2017-10-10T07:12:53Z
      DOI: 10.1016/j.aca.2017.09.023
       
 
 
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