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Publisher: Elsevier   (Total: 3030 journals)

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Showing 1 - 200 of 3030 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 20, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 16, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 79, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 22, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 27, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 4)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 5, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 303, 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  
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: 196, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 9, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription   (Followers: 1)
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 21, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 5, 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: 3, 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)
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: 20)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 120, SJR: 5.2, h-index: 222)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.265, h-index: 53)
Advanced Powder Technology     Hybrid Journal   (Followers: 16, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 8, 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: 24, SJR: 0.169, h-index: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 6, SJR: 1.054, h-index: 35)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 10, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 21, 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: 26, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 0.9, h-index: 30)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 2.139, h-index: 42)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 24, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 8, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 16, SJR: 0.223, h-index: 22)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 4)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Ecological Research     Full-text available via subscription   (Followers: 39, 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: 38, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 41, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
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: 18, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
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: 33, 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: 4)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 4)
Advances in Life Course Research     Hybrid Journal   (Followers: 7, SJR: 0.764, h-index: 15)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
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: 5, 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: 21)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 6, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 3)
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: 20, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 14)
Advances in Pharmacology     Full-text available via subscription   (Followers: 13, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 8)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 17, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 56)
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: 1, SJR: 0.1, h-index: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 332, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 7)
Advances in Surgery     Full-text available via subscription   (Followers: 6, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 28, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 14)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 12)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 42, 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: 304, 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: 4, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 7, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 390, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 29, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 36, 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: 48, 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: 3, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 9, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 5)
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: 7, 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: 5, SJR: 0.776, h-index: 35)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 6, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 45, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 5)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 3)
American Heart J.     Hybrid Journal   (Followers: 45, 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: 34, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 6, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 32, 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: 31, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 48, 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: 174, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 51, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 2)
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: 22, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 23, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 21, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 32, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 13, 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: 52, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 3)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 2, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 38, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 154, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 7, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 10)
Anesthésie & Réanimation     Full-text available via subscription  
Anesthesiology Clinics     Full-text available via subscription   (Followers: 21, 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: 143, 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   (SJR: 0.394, h-index: 30)
Annales d'Urologie     Full-text available via subscription  
Annales de Cardiologie et d'Angéiologie     Full-text available via subscription   (SJR: 0.177, h-index: 13)
Annales de Chirurgie de la Main et du Membre Supérieur     Full-text available via subscription  
Annales de Chirurgie Plastique Esthétique     Full-text available via subscription   (Followers: 2, SJR: 0.354, h-index: 22)
Annales de Chirurgie Vasculaire     Full-text available via subscription   (Followers: 1)

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Journal Cover Analytica Chimica Acta
  [SJR: 1.548]   [H-I: 152]   [38 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0003-2670 - ISSN (Online) 1873-4324
   Published by Elsevier Homepage  [3030 journals]
  • Technical aspects and challenges of colorimetric detection with
           microfluidic paper-based analytical devices (μPADs) - A review
    • Authors: Giorgio Gianini Morbioli; Thiago Mazzu-Nascimento; Amanda M. Stockton; Emanuel Carrilho
      Pages: 1 - 22
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Giorgio Gianini Morbioli, Thiago Mazzu-Nascimento, Amanda M. Stockton, Emanuel Carrilho
      Paper-based devices are a leading alternative among the main analytical tools for point-of-care testing, due to their portability, low-cost, and ease-of-use. Colorimetric readouts are the most common method of detection in these microfluidic devices, enabling qualitative, semi-quantitative and fully quantitative analysis of multiple analytes. There is a multitude of ways to obtain a colorimetric output in such devices, including nanoparticles, dyes, redox and pH indicators, and each has unique drawbacks and benefits. There are also multiple variables that impact the analysis of colorimetric reactions in microfluidic paper-based systems, including color homogeneity, image capture methods, and the data handling itself. Here, we present a critical review of recent developments and challenges of colorimetric detection on microfluidic paper-based analytical devices (μPADs), and present thoughts and insights towards future perspectives in the area to improve the use of colorimetric readouts in conjunction with μPADs.
      Graphical abstract image

      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.03.037
      Issue No: Vol. 970 (2017)
       
  • Pyrenyl carbon nanostructures for ultrasensitive measurements of
           formaldehyde in urine
    • Authors: Gayan Premaratne; Sabrina Farias; Sadagopan Krishnan
      Pages: 23 - 29
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Gayan Premaratne, Sabrina Farias, Sadagopan Krishnan
      Measurement of ultra-low (e.g., parts-per-billion) levels of small-molecule markers in body fluids (e.g., serum, urine, saliva) involves a considerable challenge in view of designing assay strategies with sensitivity and selectivity. Herein we report for the first time an amperometric nano-bioelectrode design that uniquely combines 1-pyrenebutyric acid units pi-pi stacked with carboxylated multiwalled carbon nanotubes on the surface of gold screen printed electrodes for covalent attachment of NAD+ dependent formaldehyde dehydrogenase (FDH). The designed enzyme bioelectrode offered 6 ppb formaldehyde detection in 10-times diluted urine with a wide dynamic range of 10 ppb to 10 ppm. Fourier transform infrared, Raman, and electrochemical impedance spectroscopic characterizations confirmed the successful design of the FDH bioelectrode. Flow injection analysis provided lower detection limit and greater affinity for formaldehyde (apparent KM 9.6 ± 1.2 ppm) when compared with stirred solution method (apparent KM 19.9 ± 4.6 ppm). Selectivity assays revealed that the bioelectrode was selective toward formaldehyde with a moderate cross-reactivity for acetaldehyde (∼25%) and negligible cross-reactivity toward propanaldehyde, acetone, methanol, and ethanol. Formaldehyde is an indoor pollutant, and studies have indicated neurotoxic characteristics and systemic toxic effects of this compound upon chronic and high doses of exposure. Moreover, reported chromatography and mass spectrometry methods identified elevated urine formaldehyde levels in patients with bladder cancer, dementia, and early stages of cognitive impairments compared to healthy people. Results demonstrate that pyrenyl carbon nanostructures-based FDH bioelectrode design represents novelty and simplicity for enzyme-selective electrochemical quantitation of small 30 Da formaldehyde. Broader applicability of the presented approach for other small-molecule markers is feasible that requires only the design of appropriate marker-specific enzyme systems or receptor molecules.
      Graphical abstract image

      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.03.032
      Issue No: Vol. 970 (2017)
       
  • Discriminative sensing of DOPA enantiomers by cyclodextrin anchored
           graphene nanohybrids
    • Authors: Salih Ates; Erhan Zor; Ilker Akin; Haluk Bingol; Sabri Alpaydin; Emine G. Akgemci
      Pages: 30 - 37
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Salih Ates, Erhan Zor, Ilker Akin, Haluk Bingol, Sabri Alpaydin, Emine G. Akgemci
      Discriminative sensing of chiral species with a convenient and robust system is a challenge in chemistry, pharmaceutics and particularly in biomedical science. Advanced nanohybrid materials for discrimination of these biologically active molecules can be developed by combination of individual obvious advantages of different molecular scaffolds. Herein, we report on the comparison of the performance of cyclodextrin functionalized graphene derivatives (x-CD/rGO, x: α-, β-, γ-) for discrimination of DOPA enantiomers. Within this respect, electrochemical measurements were conducted and the experimental results were compared to molecular docking method. Thanks to cavity size of γ-CD and the unique properties of graphene, rGO/γ-CD nanohybrid is capable of selective recognition of DOPA enantiomers. Limit of detection (LOD) value and sensitivity were determined as 15.9 μM and 0.2525 μA μM−1 for D-DOPA, and 14.9 μM and 0.6894 μA μM−1 for L-DOPA.
      Graphical abstract image

      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.03.052
      Issue No: Vol. 970 (2017)
       
  • Low-cost humic acid-bonded silica as an effective solid-phase extraction
           sorbent for convenient determination of aflatoxins in edible oils
    • Authors: Neng-Zhi Zhou; Ping Liu; Xiao-Chuan Su; Yan-Hua Liao; Ning-Sheng Lei; Yong-Hong Liang; Shao-Huan Zhou; Wen-Si Lin; Jie Chen; Yu-Qi Feng; Yang Tang
      Pages: 38 - 46
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Neng-Zhi Zhou, Ping Liu, Xiao-Chuan Su, Yan-Hua Liao, Ning-Sheng Lei, Yong-Hong Liang, Shao-Huan Zhou, Wen-Si Lin, Jie Chen, Yu-Qi Feng, Yang Tang
      Aflatoxins (AFs) are highly toxic, mutagenic, carcinogenic, and teratogenic secondary metabolites produced by the toxigenic fungi Aspergillus flavus and Aspergillus parasiticus. AFs tend to contaminate a wide range of foods which is a serious and recurring food safety problem worldwide. Currently, immunoaffinity chromatography (IAC) has become the most conventional sample clean-up method for determining AFs in foodstuffs. However, IAC method is limited in the large-scale food analysis because it requires the use of expensive disposable cartridges and the IA procedure is time-consuming. Herein, to achieve the cost-effective determination of AFs in edible oils, we developed a promising solid-phase extraction (SPE) method based on commercially available humic acid-bonded silica (HAS) sorbent, followed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) analysis. In HAS-SPE, AFs can be captured by the HAS sorbent with both hydrophobic and hydrophilic interactions, whereas the oil matrix was captured only with the hydrophobic interactions. The oil matrix can be sufficiently washed off with isopropanol, while the AFs were still retained on the SPE packing, thus achieving selective extraction of AFs and clean-up of oil matrices. Under the optimal conditions of HAS-SPE, satisfactory recoveries ranging from 82% to 106% for four AFs (B1, B2, G1, and G2) were achieved in various oil matrices, containing blended oil, tea oil, rapeseed oil, peanut oil, sunflower seed oil, corn oil, blended olive oil, rice oil, soybean oil, and sesame oil. Only minor matrix effects ranging from 99% to 105% for four AFs were observed. Moreover, the LODs of AFs between 0.012 and 0.035 μg/kg completely meet the regulatory levels fixed by the EU, China or other countries. The methodology was further validated for assaying the naturally contaminated peanut oils, and consistent results between the HAS-SPE and the referenced IAC were obtained. In addition, HAS-SPE can directly treat diluted oil sample without liquid-liquid extraction and is automatable, thus making it simple and convenient for the large-scale determination of AFs in edible oils. Using this method, we successfully detected four AFs in the naturally contaminated peanut oils, which is, to the best of our knowledge, the first report about the determination of AFs in edible oils using HA-based SPE.
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      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.02.029
      Issue No: Vol. 970 (2017)
       
  • Ultrathin Au nanowires assisted magnetic graphene-silica ZIC-HILIC
           composites for highly specific enrichment of N-linked glycopeptides
    • Authors: Fenglong Jiao; Fangyuan Gao; Heping Wang; Yulin Deng; Yangjun Zhang; Xiaohong Qian; Yukui Zhang
      Pages: 47 - 56
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Fenglong Jiao, Fangyuan Gao, Heping Wang, Yulin Deng, Yangjun Zhang, Xiaohong Qian, Yukui Zhang
      Protein glycosylation has been proven to participate in a variety of complex biological processes; however, the low abundance of glycopeptides in natural samples makes it essential to develop methods to isolate and enrich glycopeptides. In this study, a novel ultrathin Au nanowire assisted zwitterionic hydrophilic magnetic graphene oxide (GO-Fe3O4/SiO2/AuNWs/L-Cys) was synthesized with the good biocompatibility of GO, strong magnetic responses of Fe3O4, large surface area of ultrathin Au nanowires and excellent hydrophilicity of L-Cys via four simple and rapid steps. The ultrathin Au nanowires have a one-dimensional structure and were easily grafted with an abundant amount of L-Cys for the enrichment of glycopeptides. After the GO-Fe3O4/SiO2/AuNWs/L-Cys composites were applied to glycopeptide enrichment, 26 glycopeptides from a human IgG digest could be identified, with a detection limit as low as 10 fmol. Due to the abundant amount of grafted L-Cys, the composites also showed a large binding capacity (150 μg mg−1). Furthermore, the composites were applied for the analysis of real biological samples. A total of 793 glycopeptides from 467 glycoproteins were identified in three replicate analyses of 40 μg of mouse liver proteins. The results demonstrated the great potential of GO-Fe3O4/SiO2/AuNWs/L-Cys composites for the analysis of glycoproteins.
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      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.03.014
      Issue No: Vol. 970 (2017)
       
  • An entropy-driven signal amplifying strategy for real-time monitoring of
           DNA methylation process and high-throughput screening of methyltransferase
           inhibitors
    • Authors: Siyi Chen; Huan Ma; Wang Li; Zhou Nie; Shouzhuo Yao
      Pages: 57 - 63
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Siyi Chen, Huan Ma, Wang Li, Zhou Nie, Shouzhuo Yao
      Based on the entropy-driven toehold-mediated hairpin displacement (ETHDA), a facile and sensitive one-step fluorescence sensing platform has been proposed for the evaluation DNA methylation process catalyzed by methyltransferase (MTase). In this designed system, a hairpin probe is methylated by DNA adenine methylation (Dam) MTase and cleaved by DpnI endonuclease successively, liberating a catalyzer strand to initiate the signal amplification. The fluorescence intensity is increasing upon the catalyzer strand triggered circulating procedure of the ETHDA process. It is proved that the proposed biosensor is free of intricate procedures and avoids the interference of added amplification enzymes. According to the obtained result, the novel assay is exceedingly sensitive and selective in MTase detection with a low detection limit of 0.01 U mL−1 and a wide linear range of 0.01–100 U mL−1, which indicatives of this method a great candidate for monitoring DNA methylation. Moreover, this biosensor can offer practical applications in the high-throughput screening of MTase inhibitors, of which broadens the potential in the clinical diagnostics and related biomedical research.
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      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.03.017
      Issue No: Vol. 970 (2017)
       
  • Enhanced photoresponsive polyethyleneimine/citric acid co-carbonized dots
           for facile and selective sensing and intracellular imaging of cobalt ions
           at physiologic pH
    • Authors: Wen-Sheng Zou; Qing-Chun Zhao; Jun Zhang; Xiao-Ming Chen; Xiu-Fang Wang; Lin Zhao; Shao-Hua Chen; Ya-Qin Wang
      Pages: 64 - 72
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Wen-Sheng Zou, Qing-Chun Zhao, Jun Zhang, Xiao-Ming Chen, Xiu-Fang Wang, Lin Zhao, Shao-Hua Chen, Ya-Qin Wang
      Whether as an important biological element or as a radioactive source/medicine, the monitoring of trace levels of cobalt ions (Co) has become a non-negligible factor for human health and green environment. Current technologies for the detection of Co are cost-expensive and time-consuming, and require cumbersome sample pretreatment process. Herein a novel sensing platform has been developed for Co detection based on the quenching of the enhanced fluorescence signal of polyamine functionalized C-dots. Amine groups at the surface of the C-dots can capture Zn2+/Cd2+ to form coordination compound, which can inhibit the photoinduced electron transfer pathways of C-dots and then induce the fluorescence enhancement of the C-dots by ∼80% margin. Also, Co interacts with these amine groups to form an absorbent complex, which can strongly quench the enhanced fluorescence of C-dots via an inner filter effect. This C-dots-based probe showed a wide linear response to Co with a concentration ranging from 0.012 to 12 μM, and a detection limit of 8.0 nM and RSD of 5.7% (n = 5). Significantly, the C-Dots exhibit excellent properties, such as negligible cytotoxicity, excellent biocompatibility, low-cost and high photostability, etc., which make C-dots favorable for label-free monitoring of Co and then successfully applied to the confocal imaging of intracellular Co.
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      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.03.018
      Issue No: Vol. 970 (2017)
       
  • Graphene-coated polymeric anion exchangers for ion chromatography
    • Authors: Kai Zhang; Minyi Cao; Chaoyan Lou; Shuchao Wu; Peimin Zhang; Mingyu Zhi; Yan Zhu
      Pages: 73 - 81
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Kai Zhang, Minyi Cao, Chaoyan Lou, Shuchao Wu, Peimin Zhang, Mingyu Zhi, Yan Zhu
      Carbonaceous stationary phases have gained much attention for their peculiar selectivity and robustness. Herein we report the fabrication and application of a graphene-coated polymeric stationary phase for anion exchange chromatography. The graphene-coated particles were fabricated by a facile evaporation-reduction method. These hydrophilic particles were proven appropriate substrates for grafting of hyperbranched condensation polymers (HBCPs) to make pellicular anion exchangers. The new phase was characterized by zeta potentials, Fourier transform infrared spectroscopy, thermogravimetry and scanning electron microscope. Frontal displacement chromatography showed that the capacities of the anion exchangers were tuned by both graphene amount and HBCPs layer count. The chromatographic performance of graphene-coated anion exchangers was demonstrated with separation of inorganic anions, organic acids, carbohydrates and amino acids. Good reproducibility was obtained by consecutive injections, indicating high chemical stability of the coating.
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      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.03.015
      Issue No: Vol. 970 (2017)
       
  • Electrospun Nafion-Polyacrylonitrile nanofibers as an ion exchange
           ultrathin layer chromatographic stationary phase
    • Authors: Yanhui Wang; Susan V. Olesik
      Pages: 82 - 90
      Abstract: Publication date: 1 June 2017
      Source:Analytica Chimica Acta, Volume 970
      Author(s): Yanhui Wang, Susan V. Olesik
      An ion-exchange method to separate charged biomolecules on ultrathin layer chromatographic (UTLC) plates using electrospun Nafion-Polyacrylonitrile (PAN) nanofibers as the stationary phase is described. Sulfonate groups on Nafion provide the ion-exchange sites. The addition of PAN (a higher molecular weight polymer than Nafion) was used to facilitate the nanofiber formation process using electrospinning. Electrospinning parameters and separation conditions were optimized using fractional factorial design and response surface methodology. Nafion-PAN nanofibers containing 45% (w/w) Nafion with 0.407 mmol/g of SO3H group and 16.0 mmol/g of fluorine as an ion exchange stationary phase for UTLC were evaluated using the separations of amino acids and proteins, followed by visualizations using ninhydrin and fluorescamine, respectively. The electrospun Nafion-PAN plates showed high chemical stability under various mobile phase conditions. Mobile phase velocity decreased with the addition of Nafion into the electrospinning solutions. The sources of band broadening of analyte spots were investigated. The separation of amino acids showed high selectivity and separation efficiency. The separation of four proteins demonstrated the feasibility of Nafion-PAN UTLC for separating large biomolecules.
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      PubDate: 2017-04-23T07:33:41Z
      DOI: 10.1016/j.aca.2017.03.025
      Issue No: Vol. 970 (2017)
       
  • Rapid imaging and detection of circulating tumor cells using a wide-field
           fluorescence imaging system
    • Authors: Tomoko Yoshino; Kaori Takai; Ryo Negishi; Tatsuya Saeki; Hisashige Kanbara; Yoshihito Kikuhara; Tadashi Matsunaga; Tsuyoshi Tanaka
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Tomoko Yoshino, Kaori Takai, Ryo Negishi, Tatsuya Saeki, Hisashige Kanbara, Yoshihito Kikuhara, Tadashi Matsunaga, Tsuyoshi Tanaka
      Circulating tumor cells (CTCs) provide potentially accessible in vivo sources of metastatic cancer cells. As such, considerable focus has been placed on analyzing the genetics of single-CTCs. Prior to these analyses, however, CTCs must first be detected within the blood samples of cancer patients. Current methods for detection of CTCs by fluorescence microscopy require the analysis of hundreds of images per blood sample, making this a time-consuming process that creates a bottleneck in CTC analysis. In this study, we therefore developed a wide-field fluorescence imaging system for rapid CTC detection. For these analyses, CTCs were first isolated using the microcavity array (MCA), a micro-sized filter for CTC recovery that separates cells based on differences in cell size and deformability. Notably, the proposed imaging system enabled rapid (∼10 s) visualization of all stained cells within the 6 mm × 6 mm MCA field via one-shot imaging. Furthermore, the morphology of the cells in the resulting images accurately reflected that observed by conventional microscopy. In total, isolation and detection of CTCs using the MCA combined with our novel wide-field fluorescence imaging system was achieved within 1 h. Thus, our proposed system will provide rapid CTC detection system.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.03.030
      Issue No: Vol. 969 (2017)
       
  • Proximity hybridization-regulated catalytic DNA hairpin assembly for
           electrochemical immunoassay based on in situ DNA template-synthesized Pd
           nanoparticles
    • Authors: Fuyi Zhou; Yao Yao; Jianjun Luo; Xing Zhang; Yu Zhang; Dengyang Yin; Fenglei Gao; Po Wang
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Fuyi Zhou, Yao Yao, Jianjun Luo, Xing Zhang, Yu Zhang, Dengyang Yin, Fenglei Gao, Po Wang
      Novel hybridization proximity-regulated catalytic DNA hairpin assembly strategy has been proposed for electrochemical immunoassay based on in situ DNA template-synthesized Pd nanoparticles as signal label. The DNA template-synthesized Pd nanoparticles were characterized with atomic force microscopic and X-ray photoelectron spectroscopy. The highly efficient electrocatalysis by DNA template synthesized Pd nanoparticles for NaBH4 oxidation produced an intense detection signal. The label-free electrochemical method achieved the detection of carcinoembryonic antigen (CEA) with a linear range from 10−15 to 10−11 g mL−1 and a detection limit of 0.43 × 10−15 g mL−1. Through introducing a supersandwich reaction to increase the DNA length, the electrochemical signal was further amplified, leading to a detection limit of 0.52 × 10−16 g mL−1. And it rendered satisfactory analytical performance for the determination of CEA in serum samples. Furthermore, it exhibited good reproducibility and stability; meanwhile, it also showed excellent specificity due to the specific recognition of antigen by antibody. Therefore, the DNA template synthesized Pd nanoparticles based signal amplification approach has great potential in clinical applications and is also suitable for quantification of biomarkers at ultralow level.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.03.038
      Issue No: Vol. 969 (2017)
       
  • Quantitative determination of polysulfide in albumins, plasma proteins and
           biological fluid samples using a novel combined assays approach
    • Authors: Mayumi Ikeda; Yu Ishima; Akitomo Shibata; Victor T.G. Chuang; Tomohiro Sawa; Hideshi Ihara; Hiroshi Watanabe; Ming Xian; Yuya Ouchi; Taro Shimizu; Hidenori Ando; Masami Ukawa; Tatsuhiro Ishida; Takaaki Akaike; Masaki Otagiri; Toru Maruyama
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Mayumi Ikeda, Yu Ishima, Akitomo Shibata, Victor T.G. Chuang, Tomohiro Sawa, Hideshi Ihara, Hiroshi Watanabe, Ming Xian, Yuya Ouchi, Taro Shimizu, Hidenori Ando, Masami Ukawa, Tatsuhiro Ishida, Takaaki Akaike, Masaki Otagiri, Toru Maruyama
      Hydrogen sulfide (H2S) signaling involves polysulfide (RSSnSR′) formation on various proteins. However, the current lack of sensitive polysulfide detection assays poses methodological challenges for understanding sulfane sulfur homeostasis and signaling. We developed a novel combined assay by modifying Sulfide Antioxidant Buffer (SAOB) to produce an “Elimination Method of Sulfide from Polysulfide” (EMSP) treatment solution that liberates sulfide, followed with methylene blue (MB) sulfide detection assay. The combined EMSP-MB sulfide detection assay performed on low molecular weight sulfur species showed that sulfide was produced from trisulfide compounds such as glutathione trisulfide and diallyl trisulfide, but not from the thiol compounds such as cysteine, cystine and glutathione. In the case of plasma proteins, this novel combined detection assay revealed that approximately 14.7, 1.7, 3.9, 3.7 sulfide mol/mol released from human serum albumin, α1-anti-trypsin, α1-acid glycoprotein and ovalbumin, respectively, suggesting that serum albumin is a major pool of polysulfide in human blood circulation. Taken together with the results of albumins of different species, the liberated sulfide has a good correlation with cysteine instead of methionine, indicating the site of incorporation of polysulfide is cysteine. With this novel sulfide detention assay, approximately 8,000, 120 and 1100 μM of polysulfide concentrations was quantitated in human healthy plasma, saliva and tear, respectively. Our promising polysulfide specific detection assay can be a very important tool because quantitative determination of polysulfide sheds light on the functional consequence of protein-bound cysteine polysulfide and expands the research area of reactive oxygen to reactive polysulfide species.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.03.027
      Issue No: Vol. 969 (2017)
       
  • Combination of electrospray ionization, atmospheric pressure
           photoionization and laser desorption ionization Fourier transform ion
           cyclotronic resonance mass spectrometry for the investigation of complex
           mixtures – Application to the petroleomic analysis of bio-oils
    • Authors: Jasmine Hertzog; Vincent Carré; Yann Le Brech; Colin Logan Mackay; Anthony Dufour; Ondřej Mašek; Frédéric Aubriet
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Jasmine Hertzog, Vincent Carré, Yann Le Brech, Colin Logan Mackay, Anthony Dufour, Ondřej Mašek, Frédéric Aubriet
      The comprehensive description of complex mixtures such as bio-oils is required to understand and improve the different processes involved during biological, environmental or industrial operation. In this context, we have to consider how different ionization sources can improve a non-targeted approach. Thus, the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been coupled to electrospray ionization (ESI), laser desorption ionization (LDI) and atmospheric pressure photoionization (APPI) to characterize an oak pyrolysis bio-oil. Close to 90% of the all 4500 compound formulae has been attributed to CxHyOz with similar oxygen class compound distribution. Nevertheless, their relative abundance in respect with their double bound equivalent (DBE) value has evidenced significant differences depending on the ion source used. ESI has allowed compounds with low DBE but more oxygen atoms to be ionized. APPI has demonstrated the efficient ionization of less polar compounds (high DBE values and less oxygen atoms). The LDI behavior of bio-oils has been considered intermediate in terms of DBE and oxygen amounts but it has also been demonstrated that a significant part of the features are specifically detected by this ionization method. Thus, the complementarity of three different ionization sources has been successfully demonstrated for the exhaustive characterization by petroleomic approach of a complex mixture.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.03.022
      Issue No: Vol. 969 (2017)
       
  • Accurate and sensitive determination of molar fractions of 13C-Labeled
           intracellular metabolites in cell cultures grown in the presence of
           isotopically-labeled glucose
    • Authors: Mario Fernández-Fernández; Pablo Rodríguez-González; David Hevia Sánchez; Pedro González-Menéndez; Rosa M. Sainz Menéndez; J. Ignacio García Alonso
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Mario Fernández-Fernández, Pablo Rodríguez-González, David Hevia Sánchez, Pedro González-Menéndez, Rosa M. Sainz Menéndez, J. Ignacio García Alonso
      This work describes a methodology based on multiple linear regression and GC-MS for the determination of molar fractions of isotopically-labeled intracellular metabolites in cell cultures. Novel aspects of this work are: i) the calculation of theoretical isotopic distributions of the different isotopologues from an experimentally measured value of % 13C enrichment of the labeled precursor ii) the calculation of the contribution of lack of mass resolution of the mass spectrometer and different fragmentation mechanism such as the loss or gain of hydrogen atoms in the EI source to measure the purity of the selected cluster for each metabolite and iii) the validation of the methodology not only by the analysis of gravimetrically prepared mixtures of isotopologues but also by the comparison of the obtained molar fractions with experimental values obtained by GC-Combustion-IRMS based on 13C/12C isotope ratio measurements. The method is able to measure molar fractions for twenty-eight intracellular metabolites derived from glucose metabolism in cell cultures grown in the presence of 13C-labeled Glucose. The validation strategies demonstrate a satisfactory accuracy and precision of the proposed procedure. Also, our results show that the minimum value of 13C incorporation that can be accurately quantified is significantly influenced by the calculation of the spectral purity of the measured cluster and the number of 13C atoms of the labeled precursor. The proposed procedure was able to accurately quantify gravimetrically prepared mixtures of natural and labeled glucose molar fractions of 0.07% and mixtures of natural and labeled glycine at molar fractions down to 0.7%. The method was applied to initial studies of glucose metabolism of different prostate cancer cell lines.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.03.019
      Issue No: Vol. 969 (2017)
       
  • Fluorescence probe for hypochlorous acid in water and its applications for
           highly lysosome-targetable live cell imaging
    • Authors: Xiaojie Jiao; Chang Liu; Qing Wang; Kun Huang; Song He; Liancheng Zhao; Xianshun Zeng
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Xiaojie Jiao, Chang Liu, Qing Wang, Kun Huang, Song He, Liancheng Zhao, Xianshun Zeng
      Hypochloric acid (HOCl) plays important roles in cell signaling and homeostasis, such as anti-inflammation and immune regulation, pathogen response and so on. Accordingly, direct detection of HOCl at the organelle level is important for investigation of the complex contributions of HOCl to human health. In the present study, a water soluble lysosome-targeting fluorescent probe Lyso-1 bearing a hydrazone moiety as a HOCl-responsive site and a morpholine unit as a lysosomal-targeting group has been synthesized and evaluated for its ability to image lysosomal HOCl. The probe Lyso-1, based on a novel HOCl-promoted hydrazone oxidation strategy, showed a highly selective fluorescent off/on response to HOCl with the various reactive oxygen species in water. With increasing amount of ClO− from 0.5 to 2.5 μM, a linear correlation between the fluorescence intensity (570 nm) of Lyso-1 and [ClO−] was found, and the regression equation was y = 96.65 + 110.2068[ClO−] with a linear coefficient R of 0.9920. The detection limit is determined to be 60 nM. Lyso-1 demonstrated a perfect lysosomal targetable ability, and was successfully applied to image of exogenous, endogenous produced lysosomal HOCl in live L929 cells. The success of subcellular imaging indicated that the lysosome-targetable probe Lyso-1 could be used in further applications for the investigation of biological functions and pathological roles of HClO at organelle levels.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.03.020
      Issue No: Vol. 969 (2017)
       
  • An immunochromatographic assay for carcinoembryonic antigen on cotton
           thread using a composite of carbon nanotubes and gold nanoparticles as
           reporters
    • Authors: Xiaobo Jia; Tingting Song; Yan Liu; Lili Meng; Xun Mao
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Xiaobo Jia, Tingting Song, Yan Liu, Lili Meng, Xun Mao
      This paper describes a low-cost, sensitive, visual and rapid immunochromatographic assay method on cotton thread for carcinoembryonic antigen (CEA) detection by using novel carbon nanotube/gold nanoparticles (CNT/GNPs) nanocomposite reporter probe. CEA, a lung cancer protein biomarker, was used as analyte to demonstrate the principle of the immunochromatographic assay on cotton thread biosensor. In the presence of target CEA, the decreasing aggregation amount of CNT/GNPs nanocomposite reporter probes on the test zone induced directly readout by naked eye. Meanwhile, quantitative detection could be performed conveniently with a commercial available scanner. The performance with respect to sensitivity of the method was greatly improved by 2–3 magnitudes comparing with traditional gold nanoparticles (GNPs) or carbon nanotubes (CNTs) as reporter probe. Under optimal conditions, the biosensor was capable of detecting 2.32 ng/mL CEA (S/N ≥ 3) which is sensitive enough for clinical diagnosis. These results indicated the novel CNT/GNPs nanocomposite reporter probe based immunochromatographic assay on cotton thread is particularly suitable for point-of-care (POC) diagnostics in resource-limited regions.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.02.040
      Issue No: Vol. 969 (2017)
       
  • Escherichia coli adhesive coating as a chiral stationary phase for open
           tubular capillary electrochromatography enantioseparation
    • Authors: Qifeng Fu; Kailian Zhang; Die Gao; Lujun Wang; Fengqing Yang; Yao Liu; Zhining Xia
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Qifeng Fu, Kailian Zhang, Die Gao, Lujun Wang, Fengqing Yang, Yao Liu, Zhining Xia
      Bacteria, the microorganism with intrinsic chirality, have numerous fascinating chiral phenomena such as various chirality-triggered biological processes and behaviors. Herein, bacteria were firstly explored as novel chiral stationary phases in open-tubular capillary electrochromatography (OT-CEC) for enantioseparation of fluoroquinolone enantiomers and simultaneous separation of six fluoroquinolone antibiotics. The model strain, i.e. non-pathogenic Escherichia coli (E. coli) DH5α, was adhered onto the inner surface of positively charged polyethyleneimine (PEI) modified capillaries based on the bacterial adhesion characteristics and strong electrostatic interaction. The morphology and thickness of the bacteria adhesive coatings in the capillary were characterized by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Baseline separation of ofloxacin and partial separation of lomefloxacin enantiomers could be achieved by the E. coli coated columns. The preparation parameters including the coating time and concentration of bacteria that affecting the chiral resolution were intensively investigated. The electrophoretic parameters, including pH, buffer concentration and applied voltage, were also optimized. The developed method was validated (linearity, LOD, LOQ, intra-day, inter-day and column-to-column repeatability and recovery) and successfully utilized for the quantitative analysis of ofloxacin enantiomers in the ofloxacin tablets. Moreover, only a slight decrease in the separation efficiency was observed after 90 consecutive runs on the E. coli@capillary. These results demonstrated that bacteria are promising stationary phases for chiral separation in CEC.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.03.036
      Issue No: Vol. 969 (2017)
       
  • An ultra-specific and sensitive sandwich ELISA for imatinib using two
           anti-imatinib antibodies
    • Authors: Tetsuya Saita; Yuta Yamamoto; Kazuhisa Hosoya; Yutaro Yamamoto; Sakiko Kimura; Yutaka Narisawa; Masashi Shin
      Abstract: Publication date: 29 May 2017
      Source:Analytica Chimica Acta, Volume 969
      Author(s): Tetsuya Saita, Yuta Yamamoto, Kazuhisa Hosoya, Yutaro Yamamoto, Sakiko Kimura, Yutaka Narisawa, Masashi Shin
      The development of an immunoassay for a low-molecular-weight drug first requires the identification of specific antibodies that do not cross-react with the drug's metabolites. If two antibodies can simultaneously recognize the entire structure of the drug, we can then utilize them to establish an ultra-specific sandwich ELISA, free from interference due to the metabolic products of the drug. This paper reports an ultra-specific and sensitive sandwich ELISA for determination of the tyrosine kinase inhibitor imatinib using two anti-imatinib antibodies. The anti-imatinib antibodies were obtained by two partial structures of imatinib as haptens (2-(5-amino-2-methylanilino)-4-(3-pyridyl)pyrimidine and 4-{(4-methyl-1-piperazinyl)-methyl}-benzoate). Under optimized conditions, this sandwich ELISA shows a linear detection range from 64 pg mL−1 to 8 ng mL−1, and a limit of detection of approximately 64 pg mL−1 for 100-μL samples. The ELISA is specific to imatinib and while there was no cross-reactivity with the major metabolite N-desmethyl-imatinib, slight cross-reactivity was found with metabolite pyridine-N-oxide-imatinib. This assay demonstrated significantly lower cross-reactivity with metabolites than competitive ELISAs. Using this assay, drug levels were easily measured in rat blood after oral administration of imatinib via a single dose of 30 mg kg−1 or 100 mg kg−1. The levels in rat serum measured by this ELISA were comparable with those measured by HPLC, and there was a strong correlation between the values determined by the two methods (y = 0.983x + 0.081, R2 = 0.948). Thus, we have successfully developed the first specific and sensitive sandwich ELISA for imatinib using two anti-imatinib antibodies. This sandwich ELISA will be a valuable tool for therapeutic drug monitoring and pharmacokinetic studies of imatinib.
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      PubDate: 2017-04-16T02:24:28Z
      DOI: 10.1016/j.aca.2017.03.034
      Issue No: Vol. 969 (2017)
       
  • Chiral recognition and determination of enantiomeric excess by mass
           spectrometry: A review
    • Authors: Xiangying Yu; Zhong-Ping Yao
      Pages: 1 - 20
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Xiangying Yu, Zhong-Ping Yao
      Chiral analysis is of great importance to fundamental and applied research in chemical, biological and pharmaceutical sciences. Due to the superiority of mass spectrometry (MS) over other analytical methods in terms of speed, specificity and sensitivity, chiral analysis by MS has attracted much interest in recent years. Chiral analysis by MS typically involves introduction of a chiral selector to form diastereomers with analyte enantiomers, and comparison of the behaviors of diastereomers in MS. Chiral differentiation can be achieved by comparing the relative abundances of diastereomers, the thermodynamic or kinetic constants of ion-molecule reactions of diastereomers in the gas phase, the dissociation of diastereomers in MS/MS, or the mobility of diastereomers in ion mobility mass spectrometry. In this review, chiral recognition and determination of enantiomeric excess by these chiral MS methods were summarized, and the prospects of chiral analysis by MS were discussed.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.021
      Issue No: Vol. 968 (2017)
       
  • Facile fabrication of a novel 3D graphene framework/Bi nanoparticle film
           for ultrasensitive electrochemical assays of heavy metal ions
    • Authors: Lei Shi; Yangyang Li; Xiaojiao Rong; Yan Wang; Shiming Ding
      Pages: 21 - 29
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Lei Shi, Yangyang Li, Xiaojiao Rong, Yan Wang, Shiming Ding
      In this work, a novel 3D graphene framework/Bi nanoparticle (GF/BiNP) film was fabricated with a facile preparation route. 3D graphene framework with porous structures was electrochemically reduced and in situ assembled on the electrode, and BiNPs with tunable morphologies were highly dispersed on the framework by a chemical reduction. Newly-designed 3D GF/BiNP film possessed a significantly large active area, fast electron transfer ability, high mass transfer efficiency, and excellent structure stability and binding strength on electrode. To demonstrate its superior ability, electrochemical sensors for the assay of heavy metal ions were constructed. As a result, a simultaneous assay of Pb2+ and Cd2+ with ultralow detection limits (0.02 μg L−1 of Pb2+ and 0.05 μg L−1 of Cd2+, S/N = 3) and a wide linear range from 1 to 120 μg L−1 was achieved. Meanwhile, a separate analysis of Zn2+ was performed to get optimum responses, in which a low detection limit of 4.0 μg L−1 (S/N = 3) with a linear range from 40 to 300 μg L−1 was observed, confirming the versatility of the GF/BiNP film in the detection of heavy metal ions. Moreover, excellent repeatability, reproducibility and stability, and reliable assays in real water samples were realized with constructed sensors. Due to its convenient preparation, favorable structures and excellent properties, prepared 3D GF/BiNP film will find great potential for advanced applications in environment, biomedicine and energy systems.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.013
      Issue No: Vol. 968 (2017)
       
  • An electrochemical aptasensor for multiplex antibiotics detection using
           Y-shaped DNA-based metal ions encoded probes with NMOF substrate and CSRP
           target-triggered amplification strategy
    • Authors: Meng Chen; Ning Gan; Tianhua Li; Ye Wang; Qing Xu; Yinji Chen
      Pages: 30 - 39
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Meng Chen, Ning Gan, Tianhua Li, Ye Wang, Qing Xu, Yinji Chen
      An effective electrochemical aptasensor has been developed for the detection of multiplex antibiotics using Y-shaped DNA probes. These probes-based metal ions encoded the nanoscale metal-organic frameworks (NMOF) as a substrate, and circular strand-replacement DNA polymerization (CSRP) target triggered the amplification strategy. The Y-DNA probes (Y-DNA) were assembled using an assisted DNA probe (assisted DNA labeled with magnetic gold nanoparticles) which can hybridize to the captured DNA probe (consisting of aptamer and primer recognition region), and signal tags (NMOF encapsulating signal DNAs and different metal ions such as Pb2+ or Cd2+). Notably, NMOF was employed as the developed platform with a large specific area to load abundant metal ions that can produce distinguishable signals. In the presence of targets, chloramphenicol (CAP) and oxytetracycline (OTC) as models, the conformational change of the captured DNA can disassemble the Y-DNA probes that can consequently release the signal tags in the supernatant due to the high affinity of targets towards the aptamer domain than its complementary sequences. Subsequently, the exposed sequences of captured DNA serve as the initiators for triggering the target cyclic-induced polymerization with the assistance of Bst DNA polymerase. Thus, numerous signal tags could be detected by square wave voltammetry in the supernatant after magnetic separation, thereby amplifying the electrochemical signals. The proposed strategy exhibited a high sensitivity to antibiotics with a detection limit of 33 and 48 fM (S/N = 3) towards CAP and OTC, respectively. Moreover, this aptasensor showed promising applications for the detection of other analytes.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.024
      Issue No: Vol. 968 (2017)
       
  • Improving data quality and preserving HCD-generated reporter ions with
           EThcD for isobaric tag-based quantitative proteomics and proteome-wide PTM
           studies
    • Authors: Qing Yu; Xudong Shi; Yu Feng; K. Craig Kent; Lingjun Li
      Pages: 40 - 49
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Qing Yu, Xudong Shi, Yu Feng, K. Craig Kent, Lingjun Li
      Mass spectrometry (MS)-based isobaric labeling has undergone rapid development in recent years due to its capability for high throughput quantitation. Apart from its originally designed use with collision-induced dissociation (CID) and higher-energy collisional dissociation (HCD), isobaric tagging technique could also work with electron-transfer dissociation (ETD), which provides complementarity to CID and is preferred in sequencing peptides with post-translational modifications (PTMs). However, ETD suffers from long reaction time, reduced duty cycle and bias against peptides with lower charge states. In addition, common fragmentation mechanism in ETD results in altered reporter ion production, decreased multiplexing capability, and even loss of quantitation capability for some of the isobaric tags, including custom-designed dimethyl leucine (DiLeu) tags. Here, we demonstrate a novel electron-transfer/higher-energy collision dissociation (EThcD) approach that preserves original reporter ion channels, mitigates bias against lower charge states, improves sensitivity, and significantly improves data quality for quantitative proteomics and proteome-wide PTM studies. Systematic optimization was performed to achieve a balance between data quality and sensitivity. We provide direct comparison of EThcD with ETD and HCD for DiLeu- and TMT-labeled HEK cell lysate and IMAC enriched phosphopeptides. Results demonstrate improved data quality and phosphorylation localization accuracy while preserving sufficient reporter ion production. Biological studies were performed to investigate phosphorylation changes in a mouse vascular smooth muscle cell line treated with four different conditions. Overall, EThcD exhibits superior performance compared to conventional ETD and offers distinct advantages compared to HCD in isobaric labeling based quantitative proteomics and quantitative PTM studies.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.003
      Issue No: Vol. 968 (2017)
       
  • Determination of elemental composition of metals using ambient organic
           mass spectrometry
    • Authors: Christopher Shiea; Yeou-Lih Huang; Sy-Chyi Cheng; Yi-Lun Chen; Jentaie Shiea
      Pages: 50 - 57
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Christopher Shiea, Yeou-Lih Huang, Sy-Chyi Cheng, Yi-Lun Chen, Jentaie Shiea
      Conventional inorganic mass spectrometric (MS) analysis of metals can require time-consuming and tedious sample preparation. We thus report the novel and direct characterization of metals in solid samples using an organic MS technique known as electrospray laser desorption ionization mass spectrometry (ELDI/MS). No sample pretreatment was needed, and results were rapidly obtained due to the ambient and laser-based nature of ELDI/MS. Metals from samples were desorbed and ionized by laser irradiation, after which they reacted with EDTA and then post-ionized and detected as metal-EDTA complexes. Aluminum, copper, iron, lead, nickel, and zinc from plates, foils, and coins were characterized in seconds. This study demonstrates that an ESI/MS system can be easily modified to analyze metal elements in solids by involving a chelating agent, indicating a potentially promising development in MS towards the analysis of metals using organic MS.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.009
      Issue No: Vol. 968 (2017)
       
  • LC coupled to ESI, MALDI and ICP MS – A multiple hyphenation for
           metalloproteomic studies
    • Authors: Kateřina Coufalíková; Iva Benešová; Tomáš Vaculovič; Viktor Kanický; Jan Preisler
      Pages: 58 - 65
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Kateřina Coufalíková, Iva Benešová, Tomáš Vaculovič, Viktor Kanický, Jan Preisler
      A new multiple detection arrangement for liquid chromatography (LC) that supplements conventional electrospray ionization (ESI) mass spectrometry (MS) detection with two complementary detection techniques, matrix-assisted laser desorption/ionization (MALDI) MS and substrate-assisted laser desorption inductively coupled plasma (SALD ICP) MS has been developed. The combination of the molecular and elemental detectors in a single separation run is accomplished by utilizing a commercial MALDI target made of conductive plastic. The proposed platform provides a number of benefits in today's metalloproteomic applications, which are demonstrated by analysis of a metallothionein mixture. To maintain metallothionein complexes, separation is carried out at a neutral pH. The effluent is split; a major portion is directed to ESI MS while the remaining 1.8% fraction is deposited onto a plastic MALDI target. Dried droplets are overlaid with MALDI matrix and analysed consecutively by MALDI MS and SALD ICP MS. In the ESI MS spectra, the MT isoform complexes with metals and their stoichiometry are determined; the apoforms are revealed in the MALDI MS spectra. Quantitative determination of metallothionein isoforms is performed via determination of metals in the complexes of the individual protein isoforms using SALD ICP MS.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.016
      Issue No: Vol. 968 (2017)
       
  • Evaluation of coloured materials in microfluidic flow-cells for
           chemiluminescence detection
    • Authors: Kara B. Spilstead; Richard Alexander; Egan H. Doeven; Stephen J. Haswell; Neil W. Barnett; Paul S. Francis
      Pages: 66 - 73
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Kara B. Spilstead, Richard Alexander, Egan H. Doeven, Stephen J. Haswell, Neil W. Barnett, Paul S. Francis
      Recent advances in the construction of chemiluminescence flow-cells has included high precision milling of channels into a range of different polymer materials, in efforts to maximise the transfer of light from the chemical reaction to the photodetector. However, little is known of the extent that the colour of polymer materials will influence this transfer. This may become increasingly important as chemiluminescence detection zones are integrated with other operations within microfluidic devices or micro total analysis systems (μTAS). Herein, we compare microfluidic flow-cells fabricated from five polymer sheets (clear, white, black, red, blue), using two flow-cell designs (spiral and serpentine), two modes of photodetection, and four chemiluminescence reactions that provide a range of different emission colours. The direct transfer of light from the reaction within the white flow-cell channel to the photodetector made only minor contributions (10%–20%) to the measured intensity, with the majority of the measured light first interacting with the polymer material into which the channels were machined. The extent that the emitted light was absorbed or reflected by the coloured polymer materials was dependent on not only the properties of the polymer, but also the spectral distribution of the chemiluminescence. The changes in chemiluminescence intensities from absorption of light by the flow-cell materials can be accompanied by distortion of the spectral distribution.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.001
      Issue No: Vol. 968 (2017)
       
  • Synthesis of a novel nitrogen-doped carbon dot by microwave-assisted
           carbonization method and its applications as selective probes for optical
           pH (acidity) sensing in aqueous/nonaqueous media, determination of
           nitrate/nitrite, and optical recognition of NOX gas
    • Authors: Mohammad Mahdi Doroodmand; Mohsen Askari
      Pages: 74 - 84
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Mohammad Mahdi Doroodmand, Mohsen Askari
      A novel nitrogen-doped carbon dot (N-CD) was synthesized via carbonization of citric acid in the presence of triethylenetetramine as a nitrogen source. The average size of the N-doped CDs and also the quantum yield of the synthesized N-doped CDs were both estimated to be 9 ± 2 nm and 39.5%, respectively. The applications of the synthesized carbon nanostructure as a high quantum yield fluorescence probe were initially adopted in the fabrication of a novel optical pH (acidity) sensor in both aqueous and nonaqueous environments. Two optimum dynamic intervals were obtained with the ranges of1.5–5.0 and 7.0–10.0. for the fabricated pH sensor with a standard deviation of 0.09 pH (n = 4). The quantity of HClO4 inside acetic acid was determined as the degree of acidity with a linear range between 1.0 and 4.0%. Determination of nitrate (NO3 −) and nitrite (NO2 −) based on the fluorescence quenching of N-CDs was also evaluated in detail. The linear ranges for NO2 − and NO3 − species were estimated to be from 1 × 10−7to 7.5 × 10−5 and from 2.5 × 10−6 to 7.5 × 10−4 mol L−1, respectively with RSD of 3.69% (n = 5) for NO2 − and 3.54% (n = 5) for NO3 −. The LODs (X+3Sb) for both NO2 − and NO3 − were estimated to be 2.5 × 10−8 and 7.5 × 10−7 mol L−1, respectively. The synthesized N-CDs were also applicable for NOX recognition in the gaseous form at part per thousand (ppt) levels with linear ranges of 3.77–36.51 and 27.67–43.77 ppt, LOD (X+3Sb) of 1.41 ppt (n = 4) and RSD of 4.37% (n = 5). The reliability of these methods was also evaluated via the analyses of different forms of gaseous, water and rumen samples.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.041
      Issue No: Vol. 968 (2017)
       
  • An “on-off-on” fluorescent nanoprobe for recognition of chromium(VI)
           and ascorbic acid based on phosphorus/nitrogen dual-doped carbon quantum
           dot
    • Authors: Xiaojuan Gong; Yang Liu; Zhenhua Yang; Shaomin Shuang; Zeyu Zhang; Chuan Dong
      Pages: 85 - 96
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Xiaojuan Gong, Yang Liu, Zhenhua Yang, Shaomin Shuang, Zeyu Zhang, Chuan Dong
      Chromium (VI) [Cr(VI)] is a harsh environmental contaminates and has been proved to be highly toxic, carcinogenic and mutagenic. Therefore, developing an inexpensive, good selective and highly sensitive nanoprobe for the detection of Cr(VI) is in urgent demand. Recently, the highly fluorescent carbon quantum dots (CQDs) have been successfully utilized as efficient fluorescent nanoprobes for the detection of ions, pH and molecular substances. In this work, an “on-off” fluorescence phosphorus/nitrogen dual-doped CQDs (PNCQDs) probe was developed for the determination of Cr(VI) based on inner filter effect (IFE). The proposed PNCQDs nanoprobe shows its distinct merits of simplicity, convenience, fast implementation, good selectivity and high sensitivity towards Cr(VI), allowing its potential application in the determination of Cr(VI) in environment and biosystem. In addition, the chelation effect of the functional groups in reductant and Cr(VI), and the easy-conversion of Cr(VI) to reduced states (i.e. Cr(III) and Cr(0)) by reductants makes the minimization of IFE with a concomitant recovery of PNCQDs fluorescence possible. Hence, the PNCQDs/Cr(VI) hybrid was used as an “off-on” fluorescence probe for sensing ascorbic acid (AA), which is a model reductant. For the detection of Cr(VI), the linear range and the limit of detection achieved were 1.5–30 μmol/L and 23 nmol/L, respectively. For the detection of AA, the linear range and the limit of detection obtained were 5.0–200 μmol/L and 1.35 μmol/L, respectively. The as-constructed “on-off-on” PNCQDs fluorescent nanoprobe was successfully applied for detecting Cr(VI) and AA in biosystem. Furthermore, the as-constructed fluorescent sensing system was successfully applied to the analyses of AA in fresh fruits and in commercial fruit juices with satisfactory results.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.038
      Issue No: Vol. 968 (2017)
       
  • A novel near-infrared fluorescent probe for sensitive detection of
           β-galactosidase in living cells
    • Authors: Jingtuo Zhang; Cong Li; Colina Dutta; Mingxi Fang; Shuwei Zhang; Ashutosh Tiwari; Thomas Werner; Fen-Tair Luo; Haiying Liu
      Pages: 97 - 104
      Abstract: Publication date: 22 May 2017
      Source:Analytica Chimica Acta, Volume 968
      Author(s): Jingtuo Zhang, Cong Li, Colina Dutta, Mingxi Fang, Shuwei Zhang, Ashutosh Tiwari, Thomas Werner, Fen-Tair Luo, Haiying Liu
      A novel near-infrared fluorescent probe for β-galactosidase has been developed based on a hemicyanine skeleton, which is conjugated with a d-galactose residue via a glycosidic bond. The probe serves as a substrate of β-galactosidase and displays rapid and sensitive turn-on fluorescent responses to β-galactosidase in aqueous solution. A 12.8-fold enhancement of fluorescence intensity at 703 nm was observed after incubation of 10 nM of β-galactosidase with 5 μM probe for 10 min. The probe can sensitively detect as little as 0.1 nM of β-galactosidase and shows linear responses to the enzyme concentration below 1.4 nM. The kinetic study showed that the probe has high binding affinity to β-galactosidase with K m = 3.6 μM. The probe was used to detect β-galactosidase in living cells by employing the premature cell senescence model. The probe exhibited strong fluorescent signals in senescent cells but not in normal cells, which demonstrates that the probe is able to detect the endogenous senescence-associated β-galactosidase in living cells.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.039
      Issue No: Vol. 968 (2017)
       
  • A simple and rapid method for isotopic analysis of nickel, copper, and
           zinc in seawater using chelating extraction and anion exchange
    • Authors: Shotaro Takano; Masaharu Tanimizu; Takafumi Hirata; Ki-Cheol Shin; Yusuke Fukami; Katsuhiko Suzuki; Yoshiki Sohrin
      Pages: 1 - 11
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Shotaro Takano, Masaharu Tanimizu, Takafumi Hirata, Ki-Cheol Shin, Yusuke Fukami, Katsuhiko Suzuki, Yoshiki Sohrin
      Stable isotope ratios of nickel, copper, and zinc are powerful tools for elucidating the biogeochemical cycling of trace metals in the ocean. However, analytical difficulties have impeded isotopic studies of these metals. We present a simple and rapid method for simultaneous analysis of Ni, Cu, and Zn isotope ratios in seawater using NOBIAS Chelate-PA1 resin and anion exchange resin. A NOBIAS Chelate-PA1 resin column was used to quantitatively collect Ni, Cu, and Zn from seawater and thoroughly remove the seawater matrix. Subsequent anion exchange purified and separated the Ni, Cu, and Zn from each other. The blanks used in this method (0.22 ng for Ni, 0.29 ng for Cu, and 0.53 ng for Zn) were sufficiently low to determine the isotope ratios of Ni, Cu, and Zn in surface seawater. Using this method, we analyzed GEOTRACES reference seawater samples (i.e., SAFe D1 and SAFe D2), National Research Council Canada certified materials (i.e., CASS-5 and NASS-6), and seawater samples collected from different depths in the subarctic South Pacific. The results were consistent with previously reported values. This method is expected to accelerate isotopic research and contribute to our understanding of biogeochemical cycling in the ocean.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.010
      Issue No: Vol. 967 (2017)
       
  • Recent advances in stationary phases and understanding of retention in
           hydrophilic interaction chromatography. A review
    • Authors: Pavel Jandera; Petr Janás
      Pages: 12 - 32
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Pavel Jandera, Petr Janás
      Hydrophilic interaction chromatography (HILIC) is a rapidly developing liquid chromatography mode suitable for separation of strongly or moderately polar samples on polar columns in highly organic mixed mobile phases. In the past five years many new types of columns appeared based on silica gel, organic polymers and other types of supports. The present work reviews the new additions to their family. Further, the progress in the understanding of theoretical principles of the HILIC mode, especially of the role of the mobile phase, and of the adsorbed water are addressed. The amount of adsorbed water strongly depends on the type of the polar column and may be used to distinguish between “conventional HILIC” and “aqueous normal phase chromatography (ANP)”. Further, sample structural effects on the retention are treated in terms of the Linear Solvation Energy Relationship model adopted for partially ionized polar compounds. The impact of dual HILIC-reversed phase (RP) mechanism on a possible increase of the applications of some polar columns is discussed. Attention is paid also to the increasing role of the HILIC mode in various two-dimensional LC techniques and the related mobile phase compatibility problems.

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.01.060
      Issue No: Vol. 967 (2017)
       
  • Transferring results from NIR-hyperspectral to NIR-multispectral imaging
           systems: A filter-based simulation applied to the classification of
           Arabica and Robusta green coffee
    • Authors: Rosalba Calvini; Jose Manuel Amigo; Alessandro Ulrici
      Pages: 33 - 41
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Rosalba Calvini, Jose Manuel Amigo, Alessandro Ulrici
      Due to the differences in terms of both price and quality, the availability of effective instrumentation to discriminate between Arabica and Robusta coffee is extremely important. To this aim, the use of multispectral imaging systems could provide reliable and accurate real-time monitoring at relatively low costs. However, in practice the implementation of multispectral imaging systems is not straightforward: the present work investigates this issue, starting from the outcome of variable selection performed using a hyperspectral system. Multispectral data were simulated considering four commercially available filters matching the selected spectral regions, and used to calculate multivariate classification models with Partial Least Squares-Discriminant Analysis (PLS-DA) and sparse PLS-DA. Proper strategies for the definition of the training set and the selection of the most effective combinations of spectral channels led to satisfactory classification performances (100% classification efficiency in prediction of the test set).
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.011
      Issue No: Vol. 967 (2017)
       
  • Profiling of carbonyl compounds in serum by stable isotope labeling -
           Double precursor ion scan - Mass spectrometry analysis
    • Authors: Ning Guo; Chun-Yan Peng; Quan-Fei Zhu; Bi-Feng Yuan; Yu-Qi Feng
      Pages: 42 - 51
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Ning Guo, Chun-Yan Peng, Quan-Fei Zhu, Bi-Feng Yuan, Yu-Qi Feng
      Carbonyl compounds are considered as the potential biomarkers for oxidative stress and many types of diseases; therefore their determination may serve as indicator for early clinical diagnosis. Here we developed a strategy based on isotope labeling combined with liquid chromatography-double precursor ion scan-mass spectrometry (IL-LC-DPIS-MS) analysis for comprehensive profiling and relative quantitation of carbonyl compounds in human serum. First, we chose labeling reagents (2-(2-hydrazinyl-2-oxoethyl)isoquinolin-2-ium bromide, HIQB; N,N,N-triethyl-2-hydrazinyl-2-oxoethanaminium bromide, THB; Girard reagent T, GT; Girard reagent P, GP), all of which contain reactive group, isotopically labeled moiety and ionizable group to selectively label carbonyl compounds. Since HIQB labeling offered the best detection sensitivities for carbonyl compounds among these labeling reagents, we used HIQB and the corresponding isotope-labeled reagent of d 7-HIQB as the optimal isotope-labeled reagent. The HIQB and d 7-HIQB labeled carbonyl compounds can generate two characteristic product ions of m/z 130.1/137.1 under collision-induced dissociation (CID), which contain an isotope tag and therefore were used for double precursor ion scans in mass spectrometry analysis. Using this strategy, 156 carbonyl compounds candidates were detected in human serum, 12 of which were further identified by commercial standards. Subsequently, a targeted method using multiple reaction monitoring (MRM) detection mode was developed for relative quantification of carbonyl compounds in human serum from myelogenous leukemia (ML) patients and healthy controls. As a result, 44 carbonyl compounds were found to have significant difference between ML patients and healthy controls, suggesting that these carbonyl compounds may play certain roles in ML and also can serve as indicators for ML. Taken together, the isotope labeling combined with tandem mass spectrometry analysis demonstrated to be a powerful strategy for identification and quantification of carbonyl compounds in serum samples.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.006
      Issue No: Vol. 967 (2017)
       
  • Direct coupling of thin-layer chromatography-bioautography with
           electrostatic field induced spray ionization-mass spectrometry for
           separation and identification of lipase inhibitors in lotus leaves
    • Authors: Lei Zhang; Jiyao Shi; Jihe Tang; Zhihong Cheng; Xiaohui Lu; Yao Kong; Tao Wu
      Pages: 52 - 58
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Lei Zhang, Jiyao Shi, Jihe Tang, Zhihong Cheng, Xiaohui Lu, Yao Kong, Tao Wu
      In situ profiling compounds in complex matrices is important technology to develop in analytic chemistry. The aim of this study is to develop a direct coupling method of thin layer chromatography (TLC) to mass spectrometry (MS) via electrostatic field induced spray ionization (EFISI). We proposed a surface treatment method of normal-phase thin layer chromatography (TLC) plates with dimethyl silicone oil coating which successfully allowed TLC to couple to MS via EFISI. Different parameters affecting the ionization efficiency were investigated and optimized, including silicone oil concentrations, air-drying times, applied voltages, and TLC plate types. This optimized TLC-EFISI-MS method was successfully applied to examine lipase inhibitory components present in lotus leaves. Six active alkaloids including three aporphines and three benzylisoquinolines were profiled with their MSn (n = 4) data, or with a comparison with reference substances. This is the first report on the coupling EFISI-MS to TLC or TLC bioautography for in situ identification of active natural products.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.008
      Issue No: Vol. 967 (2017)
       
  • Colorimetric biosensor for the assay of paraoxon in environmental water
           samples based on the iodine-starch color reaction
    • Authors: Liangqia Guo; Zhihong Li; Huan Chen; Yarong Wu; Ling Chen; Zhiping Song; Tianran Lin
      Pages: 59 - 63
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Liangqia Guo, Zhihong Li, Huan Chen, Yarong Wu, Ling Chen, Zhiping Song, Tianran Lin
      In this work, a new colorimetric biosensor for the assay of paraoxon was developed via the conventional iodine-starch color reaction and multi-enzyme cascade catalytic reactions. In the presence of acetylcholine chloride, acetylcholinesterase (AChE) and choline oxidase (ChO) catalyzed the formation of H2O2, which then activated horseradish peroxidase (HRP) to catalyze the oxidation of KI to produce an iodine-starch color reaction. Upon exposure to paraoxon, the catalytic activity of AChE was inhibited and less H2O2 generated, resulting in a decrease in the production of I2 and a drop in the intensity of solution color. This colorimetric biosensor showed high sensitivity for the assay of paraoxon with a limit of detection 4.7 ppb and was applied for the assay of paraoxon in spiked real samples. By employing the conventional iodine-starch color reaction, this biosensor has the potential of on-site assay of OPs residues in environmental samples.
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      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.028
      Issue No: Vol. 967 (2017)
       
  • Colorimetric detection of glutathione in cells based on peroxidase-like
           activity of gold nanoclusters: A promising powerful tool for identifying
           cancer cells
    • Authors: Jiayu Feng; Pengcheng Huang; Shuizhen Shi; Ke-Yu Deng; Fang-Ying Wu
      Pages: 64 - 69
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Jiayu Feng, Pengcheng Huang, Shuizhen Shi, Ke-Yu Deng, Fang-Ying Wu
      Glutathione (GSH), the most abundant biothiol in cells, not only plays a pivotal role in protective and detoxifying functions of the cell, but also serves as a very important mediator in many cellular functions. Especially, the difference of GSH level between cancer cells and normal cells is regarded as one of most important physiological parameters for cancer diagnosis. It is thereby extremely necessary to develop a simple, sensitive, and reliable analytical method for detection of GSH in cells. On the basis of the inhibition effect of GSH on the peroxidase-like activity of GSH stabilized gold nanoclusters, here a novel and facile strategy for colorimetric detection of cellular GSH level was well established. In this sensing system, GSH can effectively inhibit the oxidation of peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a blue colored product. Under the optimized conditions, the absorbance at 652 nm against GSH concentration shows a linear relationship within a range from 2 to 25 μM with detection limit of 420 nM. This excellent property allows our approach to be used to accurately evaluate the cellular GSH levels, and it is revealed that the overall GSH level in cancer cells was much higher than that in normal cells. The presented assay will enable a powerful tool for identifying cancer cells in a simple manner for biomedical diagnosis associated with GSH.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.025
      Issue No: Vol. 967 (2017)
       
  • Functional fusion proteins and prevention of electrode fouling for a
           sensitive electrochemical immunosensor
    • Authors: A-Ram Kim; Tae Jung Park; Minseok S. Kim; In-Ho Kim; Ki-Suk Kim; Kwang Hoe Chung; Sungho Ko
      Pages: 70 - 77
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): A-Ram Kim, Tae Jung Park, Minseok S. Kim, In-Ho Kim, Ki-Suk Kim, Kwang Hoe Chung, Sungho Ko
      A highly sensitive electrochemical immunosensor was developed by preventing electrode fouling and using a novel fusion protein of silica binding polypeptides (SBP)-protein G (ProG) created by recombinant DNA technology as a functional crosslinker for rapid and self-oriented immobilization of antibodies onto silica nanoparticles (SiNPs). Antibody immobilization onto the SiNPs by the SBP-ProG could rapidly be achieved without any chemical treatment. The immunosensor was fabricated through bonding of a partially gold-deposited cyclic olefin copolymer (COC) (top substrate) and gold patterned interdigitated array COC electrode (bottom substrate). To prevent electrode fouling, human immunoglobulin G (hIgG) was immobilized onto the ceiling inside the microchannel, instead of the bottom electrode. Alkaline phosphatase (AP)-labeled anti-hIgG was allowed to immunoreact with hIgG on the ceiling, followed by addition of an enzyme to generate an oxidative peak current. A three-fold increase in current was observed from the immunosensor without any electrode fouling compared with a control with the protein functionalized electrode. Also, the SiNPs facilely coated with AP-anti-hIgG via the SBP-ProG could increase the electrochemical signal up to 20% larger than that of the AP-anti-hIgG alone. Furthermore, this immunosensor was ultrasensitive with a detection limit of 0.68 pg/mL of a biomarker associated with prostate cancer.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.026
      Issue No: Vol. 967 (2017)
       
  • Highly selective “turn-on” fluorescent sensing of fluoride ion based
           on a conjugated polymer thin film-Fe3+ complex
    • Authors: Wanchuan Ding; Jingkun Xu; Yangping Wen; Jie Zhang; Hongtao Liu; Zhouxiang Zhang
      Pages: 78 - 84
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Wanchuan Ding, Jingkun Xu, Yangping Wen, Jie Zhang, Hongtao Liu, Zhouxiang Zhang
      We designed a new fluorescent conjugated polymer thin film sensor via direct electropolymerization of the corresponding electroactive monomer M onto the surface of ITO electrode, and the thin film-Fe3+ complex was used for the highly-selective detection of fluoride ion (F−) in water environmental samples. The as-obtained thin film could effectively detect Fe3+ as a selective turn-off fluorescent sensor, and exhibited outstanding reversibility. This film in the presence of Fe3+ showed a highly selective turn-on response toward F− over other anions with a 5-fold enhancement in the fluorescence intensity. F− with a relatively wide concentration range from 10 μM to 3 mM could be determined in a rather simple and sensitive manner with a detection limit of 6.78 μM (0.128 ppm). Analytical applicability of the film-Fe3+ complex for determining the levels of F− in environmental water samples has been successfully demonstrated by fluorescent analysis with satisfactory results. This strategy will provide a new approach for the facile design of new molecular sensing devices and practical application in environments.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.027
      Issue No: Vol. 967 (2017)
       
  • Determination of nanomolar levels of reactive oxygen species in
           microorganisms and aquatic environments using a single nanoparticle-based
           optical sensor
    • Authors: Yura Kim; Youngho Kim; Jinhee Choi; Taewook Kang; Inhee Choi
      Pages: 85 - 92
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Yura Kim, Youngho Kim, Jinhee Choi, Taewook Kang, Inhee Choi
      Reactive oxygen species (ROS) are strong oxidants, and have attracted considerable attention in both biological and environmental fields. Although various methods for ROS detection, including optical and electrochemical techniques, have been developed, they still face challenging issues in terms of poor sensitivity, reproducibility, stability, and in vivo applicability. Here, we present a sensitive and selective optical sensor for ROS detection, based on single plasmonic nanoprobes and redox-active cytochrome c (Cyt c)-mediated plasmon resonance energy transfer. By measuring the spectral changes of plasmonic nanoprobes, derived from the unique molecular absorption of Cyt c in accordance with the redox state, calibration curves for H2O2, a representative ROS, in various media were obtained over a wide concentration range from 100 mM to 1 nM. Limit of detection and limit of quantification in accordance with the used medium were determined from 8.3 to 12.8 nM and from 27.6 to 42.7 nM, respectively. Selectivity coefficients for major interfering solutes were much lower than 0.1 indicating a good selectivity for ROS. From the dynamic spectral changes, we sensitively monitored ROS generated in Caenorhabditis elegans (C. elegans) exposed to graphene oxide. Based on the calibration curves, we also determined ROS levels in various aquatic environments, such as river streams and a small pond, as a way of environmental monitoring. We believe that our approach could provide an avenue for achieving dynamic and sensitive monitoring of ROS in toxicological, biological, and environmental fields in the future.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.012
      Issue No: Vol. 967 (2017)
       
  • Ferric reducing antioxidant potential (FRAP) of antioxidants using
           reaction flow chromatography
    • Authors: A. Jones; S. Pravadali-Cekic; G.R. Dennis; R. Bashir; P.J. Mahon; R.A. Shalliker
      Pages: 93 - 101
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): A. Jones, S. Pravadali-Cekic, G.R. Dennis, R. Bashir, P.J. Mahon, R.A. Shalliker
      High performance liquid chromatography coupled with post column derivatisation (HPLC-PCD) may be used to profile the antioxidant content of a sample. There are, however, drawbacks in the use of HPLC-PCD setups; namely the high volume reaction coils that are typically used lowering the observed separation efficiency. Reaction flow chromatography has the ability to overcome these inefficiencies by using a more efficient mixing technique inside the outlet fitting itself, post column reaction loops can be removed with resulting improvement in signal to noise response, plus the separation efficiency is maintained. We assessed two methods of HPLC-PCD antioxidant analysis based on the ferric reducing antioxidant power (FRAP) assay in both conventional and reaction flow HPLC-PCD modes. It was found that the reaction flow technique demonstrated significant advantages over the conventional technique in terms of signal to noise, linear range, precision and observed separation efficiency.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.032
      Issue No: Vol. 967 (2017)
       
  • The antagonistic role of chaotropic hexafluorophosphate anions and
           imidazolium cations composing ionic liquids applied as phase additives in
           the separation of tri-cyclic antidepressants
    • Authors: Magda Caban; Piotr Stepnowski
      Pages: 102 - 110
      Abstract: Publication date: 15 May 2017
      Source:Analytica Chimica Acta, Volume 967
      Author(s): Magda Caban, Piotr Stepnowski
      The main advantage of alkylimidazolium cation-based ionic liquids (ILs) as phase additives in RP-HPLC is believed to be the suppression of deleterious residual free silanols in chemically modified silica stationary phases. However, up to now, the influence of ILs was usually evaluated having in mind a particular IL salt as one compound, not as a specific mixture of cations and anions. This in fact led to some misinterpretation of observed results, very often related to the suppression effect, while in fact caused by the nature of IL anions, which contribute to the elevated chaotropicity of the separation phases. In the present study, we have attempted to consider the effect gained due to the presence of both ionic liquid entities in the mobile phase used for the separation of basic compounds. Tri-cyclic antidepressants (TCAs) were taken as representative analytes. The effect of ILs on the chromatographic separation of TCAs was investigated in comparison to common mobile phase additives and by the presentation of retention factors, tailing factors and theoretical plates. In addition, an overloading study was performed for the IL-based phases for the first time. In general, it was found that the effect of chaotropic hexafluorophosphate anions in ILs is much stronger and opposite to that caused by imidazolium cations. The overloading study gives interesting information on how imidazolium cations affect the separation of cationic analytes. Finally, the usefulness of imidazolium-based ILs as mobile phase modifiers in the RP-HPLC separation of basic compounds was discussed.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.026
      Issue No: Vol. 967 (2017)
       
  • Passive sampling of anionic pesticides using the Diffusive Gradients in
           Thin films technique (DGT)
    • Authors: Robin Guibal; Rémy Buzier; Adeline Charriau; Sophie Lissalde; Gilles Guibaud
      Pages: 1 - 10
      Abstract: Publication date: 8 May 2017
      Source:Analytica Chimica Acta, Volume 966
      Author(s): Robin Guibal, Rémy Buzier, Adeline Charriau, Sophie Lissalde, Gilles Guibaud
      DGT passive samplers using Oasis® HLB or Oasis® MAX sorbent were developed for anionic pesticides sampling. They were tested using four model compounds (i.e. bentazon, chlorsulfuron, ioxynil and mecoprop). Polyacrylamide diffusive gel was found to be more suitable than agarose gel for most anionic pesticides sampling. An elution procedure was optimized and diffusion coefficients were determined for quantitative use of the samplers. Depending on the DGT configuration used (HLB or MAX), accuracies better than 30% were demonstrated in laboratory for pH from 3 to 8 and ionic strengths from 10−2 to 1 M. Combined with the effective binding capacities of samplers (≥9 μg for each pesticide) and limits of quantification of the method (≤13 ng.L−1 using Q-TOF detector) monitoring of numerous aquatic systems can be expected. Except for ioxynil, accurate quantifications were demonstrated in laboratory using a spiked natural water for HLB-DGT whereas MAX-DGT did not give satisfactory results. A further in situ validation was performed in two rivers and showed identical detection frequency between HLB-DGT and POCIS of anionic pesticides (bentazon and mesotrione) whereas calculated concentrations, although within the same order of magnitude, could differ (<70%). HLB-DGT could therefore constitute an interesting alternative to other passive samplers for the monitoring of several anionic pesticides in aquatic systems but more work is required for quantification of molecules from hydroxybenzonitrile chemical group (ioxynil).
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.007
      Issue No: Vol. 966 (2017)
       
  • Review: Microbial analysis in dielectrophoretic microfluidic systems
    • Authors: Renny E. Fernandez; Ali Rohani; Vahid Farmehini; Nathan S. Swami
      Pages: 11 - 33
      Abstract: Publication date: 8 May 2017
      Source:Analytica Chimica Acta, Volume 966
      Author(s): Renny E. Fernandez, Ali Rohani, Vahid Farmehini, Nathan S. Swami
      Infections caused by various known and emerging pathogenic microorganisms, including antibiotic-resistant strains, are a major threat to global health and well-being. This highlights the urgent need for detection systems for microbial identification, quantification and characterization towards assessing infections, prescribing therapies and understanding the dynamic cellular modifications. Current state-of-the-art microbial detection systems exhibit a trade-off between sensitivity and assay time, which could be alleviated by selective and label-free microbial capture onto the sensor surface from dilute samples. AC electrokinetic methods, such as dielectrophoresis, enable frequency-selective capture of viable microbial cells and spores due to polarization based on their distinguishing size, shape and sub-cellular compositional characteristics, for downstream coupling to various detection modalities. Following elucidation of the polarization mechanisms that distinguish bacterial cells from each other, as well as from mammalian cells, this review compares the microfluidic platforms for dielectrophoretic manipulation of microbials and their coupling to various detection modalities, including immuno-capture, impedance measurement, Raman spectroscopy and nucleic acid amplification methods, as well as for phenotypic assessment of microbial viability and antibiotic susceptibility. Based on the urgent need within point-of-care diagnostics towards reducing assay times and enhancing capture of the target organism, as well as the emerging interest in isolating intact microbials based on their phenotype and subcellular features, we envision widespread adoption of these label-free and selective electrokinetic techniques.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.024
      Issue No: Vol. 966 (2017)
       
  • Simultaneous metabolomics and lipidomics analysis based on novel
           heart-cutting two-dimensional liquid chromatography-mass spectrometry
    • Authors: Shuangyuan Wang; Lina Zhou; Zhichao Wang; Xianzhe Shi; Guowang Xu
      Pages: 34 - 40
      Abstract: Publication date: 8 May 2017
      Source:Analytica Chimica Acta, Volume 966
      Author(s): Shuangyuan Wang, Lina Zhou, Zhichao Wang, Xianzhe Shi, Guowang Xu
      Increasing metabolite coverage by combining data from different platforms or methods can improve understanding of related metabolic mechanisms and the identification of biomarkers. However, no one method can obtain metabolomic and lipidomic information in a single analysis. In this work, aiming at collecting comprehensive information on metabolome and lipidome in a single analytical run, we developed an on-line heart-cutting two-dimensional liquid chromatography-mass spectrometry (2D-LC-MS) method. Complex metabolites from biological samples are divided into two fractions by using a precolumn. The first fraction is directly transferred and subjected to metabolomics analysis. Most lipids are retained on the precolumn until the mobile phases for lipidomics flow through; then they are subjected to lipidomics analysis. Up to 447 and 289 metabolites in plasma, including amino acids, carnitines, bile acids, free fatty acids, lyso-phospholipids, phospholipids, sphingomyelins etc. were identified within 30 min in the positive mode and negative mode, respectively. A comparison of the newly developed method with the conventional metabolomic and lipidomic approaches showed that approximately 99% features obtained by the two conventional methods can be covered with this 2D-LC method. Analytical characteristics evaluation showed the method had a wide linearity range, high sensitivity, satisfactory recovery and repeatability. These results demonstrate that this method is reliable, stable and well qualified in metabolomics analysis, particularly for large-scale metabolomics studies with small amount of samples.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.004
      Issue No: Vol. 966 (2017)
       
  • Analysis of volatile compounds by open-air ionization mass spectrometry
    • Authors: Anil Kumar Meher; Yu-Chie Chen
      Pages: 41 - 46
      Abstract: Publication date: 8 May 2017
      Source:Analytica Chimica Acta, Volume 966
      Author(s): Anil Kumar Meher, Yu-Chie Chen
      This study demonstrates a simple method for rapid and in situ identification of volatile and endogenous compounds in culinary spice samples through mass spectrometry (MS). This method only requires a holder for solid spice sample (2–3 mm) that is placed close to a mass spectrometer inlet, which is applied with a high voltage. Volatile species responsible for the aroma of the spice samples can be readily detected by the mass spectrometer. Sample pretreatment is not required prior to MS analysis, and no solvent was used during MS analysis. The high voltage applied to the inlet of the mass spectrometer induces the ionization of volatile compounds released from the solid spice samples. Furthermore, moisture in the air also contributes to the ionization of volatile compounds. Dried spices including cinnamon and cloves are used as the model sample to demonstrate this straightforward MS analysis, which can be completed within few seconds. Furthermore, we also demonstrate the suitability of the current method for rapid screening of cinnamon quality through detection of the presence of a hepatotoxic agent, i.e. coumarin.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.03.005
      Issue No: Vol. 966 (2017)
       
  • Titration of trace amounts of immunoglobulins in a microarray-based assay
           with magnetic labels
    • Authors: Yuri M. Shlyapnikov; Victor N. Morozov
      Pages: 47 - 53
      Abstract: Publication date: 8 May 2017
      Source:Analytica Chimica Acta, Volume 966
      Author(s): Yuri M. Shlyapnikov, Victor N. Morozov
      The existing immunoassay format that combines the electrophoretic collection of charged analytes on an antibody microarray with the detection of the bound analytes by magnetic beads coated with secondary antibodies displays extreme sensitivity and speed, but suffers from low precision because of high signal scatter and low signal-to-concentration ratio. Here we report three innovations that substantially improve the precision of this method and enable quantitative measurements of analyte concentrations as low as 10 fg/ml. The improvements were achieved by (i) employing parallel titration of analytes by measuring signal response to a series of sample dilutions with increasing analyte concentration, (ii) internally normalizing the signal (by relating signal intensity to that of positive controls on the same microarray) and (iii) taking measurements in the linear range of the calibration curve at concentrations close to the limit of detection. This improved method was used to quantitatively measure in human serum the titer of immunoglobulins specific to antigens secreted by Mycobacterium tuberculosis.
      Graphical abstract image

      PubDate: 2017-04-09T16:07:51Z
      DOI: 10.1016/j.aca.2017.02.037
      Issue No: Vol. 966 (2017)
       
 
 
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