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Showing 1 - 200 of 3175 Journals sorted alphabetically
A Practical Logic of Cognitive Systems     Full-text available via subscription   (Followers: 8)
AASRI Procedia     Open Access   (Followers: 14)
Academic Pediatrics     Hybrid Journal   (Followers: 28, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 22, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 90, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 25, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 33, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 5)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 6, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 376, SJR: 0.726, h-index: 43)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 27, SJR: 2.02, h-index: 104)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 2)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.172, h-index: 29)
Acta Haematologica Polonica     Free   (Followers: 1, SJR: 0.123, h-index: 8)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.604, h-index: 38)
Acta Materialia     Hybrid Journal   (Followers: 235, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 10, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 1)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 25, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.059, h-index: 77)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
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: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 6, SJR: 0.141, h-index: 3)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3, SJR: 0.112, h-index: 2)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 6)
Acute Pain     Full-text available via subscription   (Followers: 14)
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: 7)
Additive Manufacturing     Hybrid Journal   (Followers: 9, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Cement Based Materials     Full-text available via subscription   (Followers: 3)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 129, 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: 12, SJR: 2.071, h-index: 82)
Advances in Anesthesia     Full-text available via subscription   (Followers: 27, SJR: 0.169, h-index: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 10, SJR: 1.054, h-index: 35)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 10, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22, SJR: 1.286, h-index: 49)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 14, 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: 2, SJR: 0.619, h-index: 48)
Advances in Cancer Research     Full-text available via subscription   (Followers: 28, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 7, SJR: 0.9, h-index: 30)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 2.139, h-index: 42)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 3)
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: 27, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.223, h-index: 22)
Advances in Dermatology     Full-text available via subscription   (Followers: 14)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 10)
Advances in Digestive Medicine     Open Access   (Followers: 8)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 21)
Advances in Ecological Research     Full-text available via subscription   (Followers: 42, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 27, SJR: 0.486, h-index: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 6)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 42, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 7)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 54, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Genetics     Full-text available via subscription   (Followers: 14, SJR: 2.558, h-index: 54)
Advances in Genome Biology     Full-text available via subscription   (Followers: 7)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 2.325, h-index: 20)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 21, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 1, SJR: 0.396, h-index: 27)
Advances in Immunology     Full-text available via subscription   (Followers: 36, SJR: 4.152, h-index: 85)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 1.132, h-index: 42)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.274, h-index: 27)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, 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: 9)
Advances in Marine Biology     Full-text available via subscription   (Followers: 14, SJR: 1.645, h-index: 45)
Advances in Mathematics     Full-text available via subscription   (Followers: 10, SJR: 3.261, h-index: 65)
Advances in Medical Sciences     Hybrid Journal   (Followers: 6, SJR: 0.489, h-index: 25)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.44, h-index: 51)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 21)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 3)
Advances in Oncobiology     Full-text available via subscription   (Followers: 1)
Advances in Organ Biology     Full-text available via subscription   (Followers: 1)
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: 6, SJR: 0.148, h-index: 11)
Advances in Parasitology     Full-text available via subscription   (Followers: 5, SJR: 2.37, h-index: 73)
Advances in Pediatrics     Full-text available via subscription   (Followers: 24, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 10)
Advances in Pharmacology     Full-text available via subscription   (Followers: 15, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 59)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.478, h-index: 32)
Advances in Radiation Oncology     Open Access  
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.1, h-index: 2)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 5)
Advances in Space Research     Full-text available via subscription   (Followers: 374, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Surgery     Full-text available via subscription   (Followers: 9, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 29, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 17)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 46, SJR: 2.408, h-index: 94)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 0.973, h-index: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 333, 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: 6, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 9, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 429, 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: 31, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 43, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 1)
Agriculture and Natural Resources     Open Access   (Followers: 2)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 56, SJR: 1.879, h-index: 120)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.434, h-index: 14)
Air Medical J.     Hybrid Journal   (Followers: 5, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 11, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 9)
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   (Followers: 1)
Algal Research     Partially Free   (Followers: 9, SJR: 2.05, h-index: 20)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
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)
Alpha Omegan     Full-text available via subscription   (SJR: 0.121, h-index: 9)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 9, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 48, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 4)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 6)
American Heart J.     Hybrid Journal   (Followers: 50, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 50, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 42, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 10, 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: 31, SJR: 8.769, h-index: 256)
American J. of Infection Control     Hybrid Journal   (Followers: 26, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 32, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 42, 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: 190, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 62, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 6)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.249, h-index: 88)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 27, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 27, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 37, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 6)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 61, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 14)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 4, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 39, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 166, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 10, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 11)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 1)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 22, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1)

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Journal Cover Analytica Chimica Acta
  [SJR: 1.548]   [H-I: 152]   [39 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0003-2670 - ISSN (Online) 1873-4324
   Published by Elsevier Homepage  [3175 journals]
  • A two dimensional metal–organic framework nanosheets-based fluorescence
           resonance energy transfer aptasensor with circular strand-replacement DNA
           polymerization target-triggered amplification strategy for homogenous
           detection of antibiotics
    • Authors: Qian Yang; Lingying Zhou; Yong-Xiang Wu; Kai Zhang; Yuting Cao; You Zhou; Dazhen Wu; Futao Hu; Ning Gan
      Pages: 1 - 8
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Qian Yang, Lingying Zhou, Yong-Xiang Wu, Kai Zhang, Yuting Cao, You Zhou, Dazhen Wu, Futao Hu, Ning Gan
      In the study, a novel two dimensional metal–organic framework (Cu-TCPP nanosheets) based fluorescence resonance energy transfer (FRET) aptasensing platform was developed for detecting antibiotics. Cu-TCPP nanosheets were employed for quenching the background fluorescence and circular strand-replacement DNA polymerization (CSRP) for signal amplification. To fulfill the purpose, we designed an aptamer hairpin probe (HP) whose stem can be opened while specifically binding to target. Then the opened HP would bind with the primer. Under the action of polymerase, extension reaction was induced to generate double-stranded DNA (dsDNA), and then the target was released for the next cycle. Finally, SYBR Green I (SG) can bind with dsDNA to produce strong fluorescence response for quantification of target. It's worth mentioning that the fluorescence of HP/SG complex and free SG could be completely quenched by Cu-TCPP nanosheets while that of dsDNA/SG complex wouldn't be affected. Thus, the sensor produced negligible background signals. It can produce 7.5-fold improved S/N compared to a graphene oxide (GO)-based FRET aptasensor. Chloramphenicol (CAP) was chosen as the model analyte to demonstrate the feasibility of the sensor system. The detection range is broad from 0.001 to 10 ng mL−1 with a detection limit down to 0.3 pg mL−1. The proposed assay was label free and can be used in homogenous detection which greatly simplifies the complexity of operations. The strategy opens a new way to develop sensitive, in-situ and simple assay for antibiotics in foods.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.058
      Issue No: Vol. 1020 (2018)
  • The discrimination threshold: A selection criterion for analytical methods
    • Authors: Stephane Andanson; Isabelle Veissier; Max H. Feinberg
      Pages: 9 - 16
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Stephane Andanson, Isabelle Veissier, Max H. Feinberg
      Many biological studies seek to confirm the effect of a treatment on the levels of chemical markers in biological tissues. This requires choosing the analytical method best able to detect the difference between basal levels and those found after treatment. We propose a new approach to calculate a criterion we call the ‘discrimination threshold’ (DT), and we applied it to an analytical method that we developed to determine cortisol in cattle plasma to detect stress. DT is derived from the measurement uncertainty (MU), and combines the variabilities of both the analytical method and the marker. The uncertainty of the analytical method comes from the method validation study. The marker variability (here cortisol) is modeled from a literature review. The graphical representation of DT allows estimating the applicability of the method. Our analytical method is shown to perform well when the difference in blood cortisol exceeds 18 ng. mL−1.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.03.032
      Issue No: Vol. 1020 (2018)
  • Estimating the number of components and detecting outliers using Angle
           Distribution of Loading Subspaces (ADLS) in PCA analysis
    • Authors: Y.J. Liu; T. Tran; G. Postma; L.M.C. Buydens; J. Jansen
      Pages: 17 - 29
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Y.J. Liu, T. Tran, G. Postma, L.M.C. Buydens, J. Jansen
      Principal Component Analysis (PCA) is widely used in analytical chemistry, to reduce the dimensionality of a multivariate data set in a few Principal Components (PCs) that summarize the predominant patterns in the data. An accurate estimate of the number of PCs is indispensable to provide meaningful interpretations and extract useful information. We show how existing estimates for the number of PCs may fall short for datasets with considerable coherence, noise or outlier presence. We present here how Angle Distribution of the Loading Subspaces (ADLS) can be used to estimate the number of PCs based on the variability of loading subspace across bootstrap resamples. Based on comprehensive comparisons with other well-known methods applied on simulated dataset, we show that ADLS (1) may quantify the stability of a PCA model with several numbers of PCs simultaneously; (2) better estimate the appropriate number of PCs when compared with the cross-validation and scree plot methods, specifically for coherent data, and (3) facilitate integrated outlier detection, which we introduce in this manuscript. We, in addition, demonstrate how the analysis of different types of real-life spectroscopic datasets may benefit from these advantages of ADLS.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.03.044
      Issue No: Vol. 1020 (2018)
  • Highly efficient DNA extraction and purification from olive oil on a
           washable and reusable miniaturized device
    • Authors: Joana Carvalho; Gema Puertas; João Gaspar; Sarah Azinheiro; Lorena Diéguez; Alejandro Garrido-Maestu; Manuel Vázquez; Jorge Barros-Velázquez; Susana Cardoso; Marta Prado
      Pages: 30 - 40
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Joana Carvalho, Gema Puertas, João Gaspar, Sarah Azinheiro, Lorena Diéguez, Alejandro Garrido-Maestu, Manuel Vázquez, Jorge Barros-Velázquez, Susana Cardoso, Marta Prado
      Sample preparation from complex matrixes with minute DNA content could highly benefit from the miniaturization of solid phase extraction (SPE) based devices due to an increased surface area-to-volume ratio. However, the adaptation of “bench-top” based protocols for DNA purification to miniaturized devices is not as straightforward as it might seem, and several issues need to be considered. A careful evaluation of DNA extraction and purification protocols needs to be performed, taking into account the complexity of such samples, and in order to facilitate the integration with the subsequent step, normally DNA amplification. In this work a washable and reusable miniaturized device for DNA purification based on microscale solid phase extraction (μSPE), containing a commercial disposable silica membrane as the solid phase for DNA capture, was developed. The DNA purification protocol was firstly optimized by testing a set of different conditions, including buffer composition in all three steps of analysis and incubation during the elution step, with the objective of increasing the DNA yield and facilitating the integration in a miniaturized setting. This protocol was then tested with olive oil samples, including a pretreatment step also developed and optimized in this work. DNA analysis of olive oil samples is of high interest for the detection of fraudulent adulteration with oil from other seeds and for cultivar identification. The results were compared with the commercial NucleoSpin® Food kit regarding efficiency and purity of the DNA extract, by estimating the DNA yield and evaluating the absorbance ratios A260/280 and A260/230. The miniaturized DNA purification device showed better performance than the commercial kit tested, making this method a very promising sample preparation approach for olive oil and other samples with minute DNA content.

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.079
      Issue No: Vol. 1020 (2018)
  • Enhanced cleanup efficiency hydroxy functionalized-magnetic graphene oxide
           and its comparison with magnetic carboxyl-graphene for PRiME pass-through
           cleanup of strychnine and brucine in human plasma samples
    • Authors: Jian-Bo Ma; Hai-Wen Qiu; Qiu-Hong Rui; Yu-Feng Liao; Yan-Min Chen; Jin Xu; Yun Zhang; Yan Zhu; Yong-Gang Zhao
      Pages: 41 - 50
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Jian-Bo Ma, Hai-Wen Qiu, Qiu-Hong Rui, Yu-Feng Liao, Yan-Min Chen, Jin Xu, Yun Zhang, Yan Zhu, Yong-Gang Zhao
      An enhanced cleanup efficiency hydroxy functionalized-magnetic graphene oxide (EH-Mag-GO) fully covered porous nano-titania as coating has been designed and synthesized. It has been evaluated in PRiME (process, robustness, improvements, matrix effects, ease of use) pass-through cleanup procedure for human plasma prior to analysis of strychnine and brucine by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). Comparing with the magnetic carboxyl-graphene (Mag-CG), EH-Mag-GO is much more effective for the removal of matrix effect resulted from blood phospholipids. Under optimal conditions, the results show higher cleanup efficiency of EH-Mag-GO with recoveries in the range of 89.4%–118%. The limits of quantification (LOQs) for strychnine and brucine are 0.088 μg/L and 0.092 μg/L, respectively. Especially, the EH-Mag-GO is also evaluated for reuse (20 times) without much sacrifice of the cleanup efficiency. Validation results on linearity, specificity, accuracy and precision, as well as on the application to analysis of strychnine and brucine in six cases of suspected semen strychni poisoning demonstrate the applicability to clinical studies.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.03.008
      Issue No: Vol. 1020 (2018)
  • Simultaneous determination of trace levels of multiclass fungicides in
           natural waters by solid - phase microextraction - gas
           chromatography-tandem mass spectrometry
    • Authors: Maria Celeiro; Rocio Facorro; Thierry Dagnac; Maria Llompart
      Pages: 51 - 61
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Maria Celeiro, Rocio Facorro, Thierry Dagnac, Maria Llompart
      A solvent-free method based on solid-phase microextraction (SPME) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for the simultaneous determination of eleven fungicides at trace levels in different types of waters. Several experimental SPME parameters such as temperature, fibre coating, and SPME mode, were optimized in order to obtain the highest extraction efficiency. Under the optimal conditions, 100 °C, polyacrilate fibre (PA) and direct-immersion mode, the method was validated showing good linearity, repeatability and reproducibility. Recovery studies were carried out in four different real water matrices and at three concentration levels (20, 200 and 2000 ng L−1), with overall recovery values between 92 and 104% and relative standard deviations (RSD) about 10%. Limits of detection (LODs) at the low ng L−1 were obtained. The method demonstrated its suitability for the determination of fungicides in real water samples using external calibration for quantification purposes as well as for photodegradation studies at low concentration levels.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.03.014
      Issue No: Vol. 1020 (2018)
  • Mass spectrometric recommendations for Quan/Qual analysis using
           liquid-chromatography coupled to quadrupole time-of-flight mass
    • Authors: Anne-Charlotte Dubbelman; Filip Cuyckens; Lieve Dillen; Gerhard Gross; Rob J. Vreeken; Thomas Hankemeier
      Pages: 62 - 75
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Anne-Charlotte Dubbelman, Filip Cuyckens, Lieve Dillen, Gerhard Gross, Rob J. Vreeken, Thomas Hankemeier
      Background High-throughput simultaneous quantitative and qualitative (Quan/Qual) analysis is attractive to combine targeted with non-targeted analysis, e.g. in pharmacometabolomics and drug metabolism studies. This study aimed to investigate the possibilities and limitations of high-throughput Quan/Qual analysis by ultra-high performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS), to develop a widely applicable Quan/Qual UHPLC-HRMS method and to provide recommendations for Quan/Qual method development. Methods A widely applicable 4.25-min UHPLC method for small-molecules was used to investigate and optimize mass spectrometric parameters of a Synapt G2S for Quan/Qual analysis. The method was applied on a rat metabolomics study investigating the effect of the fasting state and administration of a dosing vehicle on the rat plasma metabolic profile. Results Highly important parameters for high-throughput Quan/Qual analysis were the scan mode and scan rate. A negative correlation was found between the amount of qualitative information that a method can provide and its quantitative performance (accuracy, precision, sensitivity, linear dynamic range). The optimal balance was obtained using the MSE scan mode with a short scan time of 30 ms. This 4.25-min Quan/Qual analysis method enabled quantification with accuracy and precision values ≤ 20% at the lowest quality control (QC) level and ≤15% at higher QC levels for 16 out of 19 tested analytes. It provided both parent m/z values and fragmentation spectra for compound identification with limited loss of chromatographic resolution and it revealed biologically relevant metabolites in its application to the metabolomics study. Conclusion Quan/Qual method development requires balancing between the amount of qualitative data, the quality of the quantitative data and the analysis time. Recommendations are provided for MS resolution, scan mode, scan rate, smoothing and peak integration in Quan/Qual method development and analysis.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.055
      Issue No: Vol. 1020 (2018)
  • Use of dielectric barrier discharge ionization to minimize matrix effects
           and expand coverage in pesticide residue analysis by liquid
           chromatography-mass spectrometry
    • Authors: Felipe J. Lara-Ortega; José Robles-Molina; Sebastian Brandt; Alexander Schütz; Bienvenida Gilbert-López; Antonio Molina-Díaz; Juan F. García-Reyes; Joachim Franzke
      Pages: 76 - 85
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Felipe J. Lara-Ortega, José Robles-Molina, Sebastian Brandt, Alexander Schütz, Bienvenida Gilbert-López, Antonio Molina-Díaz, Juan F. García-Reyes, Joachim Franzke
      Although electrospray ionization (ESI) remains the gold standard ionization source for LC-MS, it exhibits two main limitations: the occurrence of matrix effects and the limited ionization coverage towards nonpolar compounds. Dielectric barrier discharge ionization (DBDI) has gained attraction in recent years as a versatile ionization method in different applications and formats. Here, we report a thorough evaluation of DBDI as ionization interface for LC-MS, which reveals attractive advantages over ESI and atmospheric pressure chemical ionization (APCI) provided its singular ionization mechanism versatility. A suite of 80 pesticides across a wide range of physicochemical properties were selected and the results were compared with both ESI and APCI sources. Using a helium plasma operated in homogeneous regime with square-wave AC waveform and relatively low voltages (2.5 kV), not only DBDI was able to ionize compounds only amenable so far by GC-MS (eg. organochlorine species), but also offered a competitive performance in terms of sensitivity when contrasted with the commercial electrospray ionization source under equivalent conditions. Unlike ESI, DBDI mechanism occurs in the gas-phase, so the method is less affected by liquid-phase surface phenomena that yield ion suppression in ESI. Data collected in the positive ion mode revealed negligible matrix effect values (<10% suppression) for most of the studied compounds in different complex matrix extracts such as wastewater, orange or olive oil. This is also consistent with the absence of adduct formation whereas with ESI source, Na adduct formation is quite common with these species. In general, both sensitivity and average limits of quantitation for DBDI were similar to those obtained by ESI and better than APCI. Results showed that analyte coverage with DBDI is enhanced with respect to ESI and APCI sources being able to effectively analyze organochlorine compounds.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.077
      Issue No: Vol. 1020 (2018)
  • Optical trapping-Raman spectroscopy (OT-RS) with embedded microscopy
           imaging for concurrent characterization and monitoring of physical and
           chemical properties of single particles
    • Authors: Zhiyong Gong; Yong-Le Pan; Gorden Videen; Chuji Wang
      Pages: 86 - 94
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Zhiyong Gong, Yong-Le Pan, Gorden Videen, Chuji Wang
      The study of physical and chemical properties of a microscopic object, such as a single particle, is made possible using optical trapping (OT) technology combined with other measuring techniques. Here we show a universal optical trap combined with Raman spectroscopy (RS) and microscopy imaging for single-particle studies. The universal optical trap is constructed using two counter-propagating hollow beams and is able to stably levitate single particles of a wide range of properties, such as transparent or absorbing materials, organic (polymers, bioaerosols, etc.) or inorganic constituents (carbon, silica, glass, etc.), and spherical or irregularly shaped morphologies. Both physical and chemical properties and their temporal evolution of the trapped particle can be characterized simultaneously using the integrated OT-RS and imaging system. We created three sample cases to demonstrate the analytical merits of the system: (I) a single particle with no change, (II) partially degraded over the measuring period, and (III) one part from the fragmentized single particle. The particles' chemical compositions, crystalline states, etc. are inferred from their Raman spectra, while their physical properties (sizes, shapes, morphologies, etc.) are revealed by images. This integrated OT-RS system provides a new approach to concurrently characterize and monitor physical and chemical properties of single micrometer-sized objects optically trapped in air.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.062
      Issue No: Vol. 1020 (2018)
  • Spectrophotometric calibration procedures to enable calibration-free
           measurements of seawater calcium carbonate saturation states
    • Authors: Erin E. Cuyler; Robert H. Byrne
      Pages: 95 - 103
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Erin E. Cuyler, Robert H. Byrne
      A simple protocol was developed to measure seawater calcium carbonate saturation states (Ωspec) spectrophotometrically. Saturation states are typically derived from the separate measurement of two other carbon system parameters, with each requiring unique instrumentation and often complex measurement protocols. Using the new protocol, the only required equipment is a thermostatted laboratory spectrophotometer. For each seawater sample, spectrophotometric measurements of pH (visible absorbance) are made in paired optical cells, one with and one without added nitric acid. Ultraviolet absorbance is measured to determine the amount of added acid based on the direct proportionality between nitrate concentration and UV absorbance. Coupled measurements of pH and the alkalinity change that accompanies the nitric acid addition allow calculation of a seawater sample's original carbonate ion concentration and saturation state. These paired absorbance measurements yield Ωspec (and other carbonate system parameters), with each sample requiring about 12 min processing time. Initially, an instrument-specific nitrate molar absorptivity coefficient must be determined (due to small but significant discrepancies in instrumental wavelength calibrations), but thereafter no further calibration is needed. In this work, the 1σ precision of replicate measurements of aragonite saturation state was found to be 0.020, and the average difference between Ωspec and Ω calculated conventionally from measured total alkalinity and pH (Ωcalc) was −0.11% ± 0.96% (a level of accuracy comparable to that obtained from spectrophotometric measurements of carbonate ion concentration). Over the entire range of experimental conditions, 0.97 < Ω < 3.17 (n = 125), all measurements attained the Global Ocean Acidification Observing Network's “weather level” goal for accuracy and 90% attained the more stringent “climate level” goal. When Ωspec was calculated from averages of duplicate samples (n = 56), the precision improved to 0.014 and the average difference between Ωspec and Ωcalc improved to −0.11% ± 0.73%. Additionally, 97% of the duplicate-based Ωspec measurements attained the “climate level” accuracy goal. These results indicate that the simple measurement protocol developed in this work should be widely applicable for monitoring fundamental seawater changes associated with ocean acidification.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.071
      Issue No: Vol. 1020 (2018)
  • Dual enzyme-free amplification strategy for ultra-sensitive fluorescent
           detection of bisphenol A in water
    • Authors: Wen Yun; Hong Wu; Lin Chen; Lizhu Yang
      Pages: 104 - 109
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Wen Yun, Hong Wu, Lin Chen, Lizhu Yang
      An ultra-sensitive strategy for bisphenol A (BPA) detection based on dual enzyme-free strategies: hybridization chain reaction (HCR) and enzyme-strand recycling reaction has been developed. The BPA aptamer can form hairpins structure by the partly self-complementary sequence. In the presence of BPA, the released BPA aptamer sequence can trigger the HCR between two hairpins to from a long nicked double-helix DNA. The tails of hairpins on the duplex DNA were closely enough to hybridize with molecular beacon (MB) on the gold nanoparticles (AuNPs) to circularly cleave the loop of MB, leading to a “turn-on” fluorescent signal. This method exhibited high sensitivity for BPA detection in a linear rang from 0.2 to 1000 pM with 0.05 pM of limit of detection. Moreover, it was successfully used for BPA detection in real water samples. Importantly, this method was simple without complex enzymatic procedure and high cost, showing a promising future for on-site detection of BPA in practical application.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.064
      Issue No: Vol. 1020 (2018)
  • A novel colorimetric aptasensor for ultrasensitive detection of cocaine
           based on the formation of three-way junction pockets on the surfaces of
           gold nanoparticles
    • Authors: Khalil Abnous; Noor Mohammad Danesh; Mohammad Ramezani; Seyed Mohammad Taghdisi; Ahmad Sarreshtehdar Emrani
      Pages: 110 - 115
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Khalil Abnous, Noor Mohammad Danesh, Mohammad Ramezani, Seyed Mohammad Taghdisi, Ahmad Sarreshtehdar Emrani
      Herein, a novel colorimetric aptasensor was introduced for detection of cocaine based on the formation of three-way junction pockets on the surfaces of gold nanoparticles (AuNPs) and the catalytic activity of the surfaces of AuNPs. Simplicity and detection of cocaine in a short time (only 35 min) are some of the unique features of the proposed sensing strategy. In the presence of cocaine, triple-fragment aptamer (TFA) forms on the surfaces of AuNPs, leading to a significant decrease of the catalytic activity of AuNPs and the color of samples remains yellow. In the absence of target, TFA does not form on the surfaces of AuNPs and 4-Nitrophenol, as a colorimetric agent, has more access to the surfaces of AuNPs, resulting in the reduction of 4-Nitrophenol and the color of sample changes from yellow to colorless. The sensing strategy showed good specificity, a limit of detection (LOD) of 440 pM and a dynamic range over 2–100 nM. The sensing method was also successfully applied to detect cocaine in spiked human serum samples with recovery of 94.71–98.63%.

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.066
      Issue No: Vol. 1020 (2018)
  • Aptamer-based microcantilever-array biosensor for profenofos detection
    • Authors: Chao Li; Guangping Zhang; Shangquan Wu; Qingchuan Zhang
      Pages: 116 - 122
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Chao Li, Guangping Zhang, Shangquan Wu, Qingchuan Zhang
      Profenofos, a highly poisonous organophosphorus pesticide, has been widely used in agricultural production. These pesticide residues have seriously influenced food security and threatened human health, and new methods with high sensitivity are greatly needed to detect profenofos. Here, we developed an aptamer-based microcantilever-array sensor operated in stress mode to detect profenofos, with advantages of being a label-free, highly sensitive, one-step immobilization method capable of quantitative and real-time detection. The microcantilevers were functionalized with a profenofos-specific aptamer (SS2-55), and then the specific binding of profenofos to aptamer induced a deflection of the microcantilever, which was monitored using an optical method in a real-time manner. The microcantilever deflection showed a positive relationship with profenofos concentration, and the detection limit was low to 1.3 ng mL−1 (3.5 nM) for profenofos, which was much lower than other aptamer-based detection methods. The selectivity of the sensor was verified with another organophosphorus pesticide. Additionally, we successfully detected profenofos dissolved in vegetable-soak solution. Our results showed that this aptamer-based microcantilever-array sensor is a convenient and label-free method for detecting profenofos in small amounts and has great potential for food-security applications.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.072
      Issue No: Vol. 1020 (2018)
  • Simultaneous elastase-, hyaluronidase- and collagenase-capillary
           electrophoresis based assay. Application to evaluate the bioactivity of
           the red alga Jania rubens
    • Authors: Syntia Fayad; Mona Tannoury; Philippe Morin; Reine Nehmé
      Pages: 134 - 141
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Syntia Fayad, Mona Tannoury, Philippe Morin, Reine Nehmé
      There have been many efforts to search for affordable and efficient cosmetic ingredients from natural sources and to evaluate their bioactivities using eco-responsible tools. Hyaluronidase, elastase and collagenase are responsible for the degradation of the main components of the extracellular matrix, namely the hyaluronic acid, elastin and collagen, respectively. The aim of this work was to develop a single capillary electrophoresis method to monitor simultaneously the activities of these three enzymes, without reactant immobilization or radioactivity use. The developed approach was used to evaluate the bioactivity of the red alga Jania rubens after microwave- or electrochemical-assisted extraction. For this purpose, the incubation time, the reactant concentrations, the separation buffer and the detection system were carefully chosen. CE with double detection system, LIF and HRMS connected in series, was used to ensure the simultaneous analysis of the substrates and products of the three enzymatic reactions. The optimized enzymatic conditions allowed the use of the same protocol to assess the 3 enzyme activities. These conditions consisted of 10 min pre-incubation of the enzyme (with alga extract) at 37 °C; 10 min incubation with the substrate at 37 °C and 10 min stop-time at 90 °C. 1.4 nL of each reaction mixture were co-injected into a 85 cm total length capillary using short-end injection. Ammonium acetate (50 mM, pH 9.0) was used for electrophoretic separation. All substrates and products were simultaneously detected in less than 10 min with good peak symmetry and efficiency, sufficient intra-day and inter-day repeatabilities (RSD < 4.5%; n = 3) and excellent LOQ (<5 nM). The results obtained using this multiple CE-based enzymatic assay showed the significant effect of Jania rubens ethanolic extracts on elastase, hyaluronidase and the metalloproteinase MMP-1.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.03.004
      Issue No: Vol. 1020 (2018)
  • PepsNMR for 1H NMR metabolomic data pre-processing
    • Authors: Manon Martin; Benoît Legat; Justine Leenders; Julien Vanwinsberghe; Réjane Rousseau; Bruno Boulanger; Paul H.C. Eilers; Pascal De Tullio; Bernadette Govaerts
      Pages: 1 - 13
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Manon Martin, Benoît Legat, Justine Leenders, Julien Vanwinsberghe, Réjane Rousseau, Bruno Boulanger, Paul H.C. Eilers, Pascal De Tullio, Bernadette Govaerts
      In the analysis of biological samples, control over experimental design and data acquisition procedures alone cannot ensure well-conditioned 1H NMR spectra with maximal information recovery for data analysis. A third major element affects the accuracy and robustness of results: the data pre-processing/pre-treatment for which not enough attention is usually devoted, in particular in metabolomic studies. The usual approach is to use proprietary software provided by the analytical instruments' manufacturers to conduct the entire pre-processing strategy. This widespread practice has a number of advantages such as a user-friendly interface with graphical facilities, but it involves non-negligible drawbacks: a lack of methodological information and automation, a dependency of subjective human choices, only standard processing possibilities and an absence of objective quality criteria to evaluate pre-processing quality. This paper introduces PepsNMR to meet these needs, an R package dedicated to the whole processing chain prior to multivariate data analysis, including, among other tools, solvent signal suppression, internal calibration, phase, baseline and misalignment corrections, bucketing and normalisation. Methodological aspects are discussed and the package is compared to the gold standard procedure with two metabolomic case studies. The use of PepsNMR on these data shows better information recovery and predictive power based on objective and quantitative quality criteria. Other key assets of the package are workflow processing speed, reproducibility, reporting and flexibility, graphical outputs and documented routines.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.067
      Issue No: Vol. 1019 (2018)
  • Microstructured optical fiber-based luminescent biosensing: Is there any
           light at the end of the tunnel' - A review
    • Authors: Sergey A. Pidenko; Natalia A. Burmistrova; Andrey A. Shuvalov; Anastasiya A. Chibrova; Yulia S. Skibina; Irina Y. Goryacheva
      Pages: 14 - 24
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Sergey A. Pidenko, Natalia A. Burmistrova, Andrey A. Shuvalov, Anastasiya A. Chibrova, Yulia S. Skibina, Irina Y. Goryacheva
      This review covers the current state of the art of luminescent biosensors based on various types of microstructured optical fiber. The unique optical and structural properties of this type of optical fiber make them one of the most promising integrated platforms for bioassays. The individual sections of this review are devoted to a) classification of microstructured optical fibers, b) microstructured optical fiber materials, c) aspects of biosensing based on the biomolecules incorporated into the microstructured optical fibers, and d) development of models for prediction of the efficiency of luminescent signal processing. The authors' views on current trends and limitations of microstructured optical fibers for biosensing as well as the most promising areas and technologies for application in analytical practice are presented.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2017.12.010
      Issue No: Vol. 1019 (2018)
  • Recent trends in atomic fluorescence spectrometry towards miniaturized
           instrumentation-A review
    • Authors: Zhirong Zou; Yujia Deng; Jing Hu; Xiaoming Jiang; Xiandeng Hou
      Pages: 25 - 37
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Zhirong Zou, Yujia Deng, Jing Hu, Xiaoming Jiang, Xiandeng Hou
      Atomic fluorescence spectrometry (AFS), as one of the common atomic spectrometric techniques with high sensitivity, simple instrumentation, and low acquisition and running cost, has been widely used in various fields for trace elemental analysis, notably the determination of hydride-forming elements by hydride generation atomic fluorescence spectrometry (HG-AFS). In recent years, the soaring demand of field analysis has significantly promoted the miniaturization of analytical atomic spectrometers or at least instrumental components. Various techniques have also been developed to approach the goal of portable/miniaturized AFS instrumentation for field analysis. In this review, potentially portable/miniaturized AFS techniques, primarily involving advanced instrumental components and whole instrumentation with references since 2000, are summarized and discussed. The discussion mainly includes five aspects: radiation source, atomizer, detector, sample introduction, and miniaturized atomic fluorescence spectrometer/system.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.01.061
      Issue No: Vol. 1019 (2018)
  • Evaluation of batch effect elimination using quality control replicates in
           LC-MS metabolite profiling
    • Authors: Ángel Sánchez-Illana; Jose David Piñeiro-Ramos; Juan Daniel Sanjuan-Herráez; Máximo Vento; Guillermo Quintás; Julia Kuligowski
      Pages: 38 - 48
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Ángel Sánchez-Illana, Jose David Piñeiro-Ramos, Juan Daniel Sanjuan-Herráez, Máximo Vento, Guillermo Quintás, Julia Kuligowski
      Systematic variation of the instrument's response both within- and between-batches is frequently observed in untarget LC-MS metabolomics involving the analysis of a large number of samples. The so-called batch effect decreases the statistical power and has a negative impact on repeatability and reproducibility of the results. As there is no standard way of assessing or correcting LC-MS batch effects and there is no single method providing optimal results in all situations, the selection of the optimal approach is not trivial. This work explores the effectiveness of a set of tools for batch effect assessment. Qualitative tools include the monitoring of spiked internal standards, principal component analysis and hierarchical cluster analysis. Quantitative tools comprise the distribution of RSDQC values, the median Pearson correlation coefficient in QCs, the ratio of random features in QCs using the runs test, as well as multivariate tools such as the δ-statistic, Silhouette plots, Principal Variance Component Analysis and the expected technical variation in the prediction. Results show that qualitative and quantitative approaches are complementary and that by limiting the analysis to QCs the power to detect and evaluate both within and between batch effects is increased. Besides, the graphical integration of outputs from multiple quantitative tools facilitates the evaluation of batch effects and it is proposed as a straightforward way for comparing and tailoring batch effect elimination approaches.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.053
      Issue No: Vol. 1019 (2018)
  • Multivariate estimation of the limit of detection by orthogonal partial
           least squares in temperature-modulated MOX sensors
    • Authors: Javier Burgués; Santiago Marco
      Pages: 49 - 64
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Javier Burgués, Santiago Marco
      Metal oxide semiconductor (MOX) sensors are usually temperature-modulated and calibrated with multivariate models such as partial least squares (PLS) to increase the inherent low selectivity of this technology. The multivariate sensor response patterns exhibit heteroscedastic and correlated noise, which suggests that maximum likelihood methods should outperform PLS. One contribution of this paper is the comparison between PLS and maximum likelihood principal components regression (MLPCR) in MOX sensors. PLS is often criticized by the lack of interpretability when the model complexity increases beyond the chemical rank of the problem. This happens in MOX sensors due to cross-sensitivities to interferences, such as temperature or humidity and non-linearity. Additionally, the estimation of fundamental figures of merit, such as the limit of detection (LOD), is still not standardized in multivariate models. Orthogonalization methods, such as orthogonal projection to latent structures (O-PLS), have been successfully applied in other fields to reduce the complexity of PLS models. In this work, we propose a LOD estimation method based on applying the well-accepted univariate LOD formulas to the scores of the first component of an orthogonal PLS model. The resulting LOD is compared to the multivariate LOD range derived from error-propagation. The methodology is applied to data extracted from temperature-modulated MOX sensors (FIS SB-500-12 and Figaro TGS 3870-A04), aiming at the detection of low concentrations of carbon monoxide in the presence of uncontrolled humidity (chemical noise). We found that PLS models were simpler and more accurate than MLPCR models. Average LOD values of 0.79 ppm (FIS) and 1.06 ppm (Figaro) were found using the approach described in this paper. These values were contained within the LOD ranges obtained with the error-propagation approach. The mean LOD increased to 1.13 ppm (FIS) and 1.59 ppm (Figaro) when considering validation samples collected two weeks after calibration, which represents a 43% and 46% degradation, respectively. The orthogonal score-plot was a very convenient tool to visualize MOX sensor data and to validate the LOD estimates.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.03.005
      Issue No: Vol. 1019 (2018)
  • Molecularly imprinted mesoporous silica nanoparticles for specific
           extraction and efficient identification of Amadori compounds
    • Authors: Xianghua Pan; Xinpei He; Zhen Liu
      Pages: 65 - 73
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Xianghua Pan, Xinpei He, Zhen Liu
      Amadori compounds are an important family of chemical species with high values in the quality control and research of food and tobacco products as well as disease diagnosis. Since they are present in a large population with close structure and nature, recognition of specific Amadori compounds from complex sample matrices presents a challenging task. Particularly, few reagents or materials that can recognize specific Amadori compounds have been reported. In this study, we synthesized molecularly imprinted mesoporous silica nanoparticles (MIMSNs) that can highly specifically recognize and efficiently extract an Amadori compound of interest from complex samples. N-(1-deoxy-d-glucose-1-yl)tryptophan (Glc-Trp), a typical Amadori compound, was used as the template and target compound. The prepared MIMSNs exhibited excellent binding properties. The cross-reactivity was only 2.9–4.8% towards interfering analogs. The binding constant and binding capacity towards the target were 66 μM and 45 μmol/g, respectively. The imprinting approach showed outstanding imprinting effect, giving an imprinting factor of 119.4. Through combining MIMSNs-based extraction with electrospray ionization-mass spectrometry (ESI-MS) and capillary electrography (CE), a targeted analysis approach was established and demonstrated to be an efficient platform for identification and determination of Glc-Trp from cigarette sample.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.078
      Issue No: Vol. 1019 (2018)
  • Automated bundled hollow fiber array-liquid-phase microextraction with
           liquid chromatography tandem mass spectrometric analysis of perfluorinated
           compounds in aqueous media
    • Authors: Shalene Xue Lin Goh; Hian Kee Lee
      Pages: 74 - 83
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Shalene Xue Lin Goh, Hian Kee Lee
      An automated bundled hollow fiber array (BHF)-liquid-phase microextraction (LPME) methodology in combination with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed for the determination of perfluorinated compounds (PFCs) in environmental aqueous matrices. Eight PFCs were considered, including perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid. Experimental parameters influencing extraction efficiency, such as number of hollow fibers in the BHF extraction device, type of extraction and desorption solvent, extraction conditions (stirring rate, temperature and duration), elution conditions and the salting out effect were examined. Under the most favourable conditions, enrichment factors of between 9 and 40 were achieved for the target compounds when extracting from 10 mL of sample. Good intra and inter-day precision were obtained with relative standard deviations of less than 12%. The linearity range investigated was between 5 and 10,000 ng L−1, with coefficients of determination (r2) ≥ 0.991. The developed method was applied for the UHPLC-MS/MS determination of environmental PFCs in industrial water discharge samples. The automation of BHF-LPME together with UHPLC-MS/MS rendered the method efficient, rapid and sensitive to determine PFCs, with the possibility of on-site real-time monitoring of contaminants in environmental waters.

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.03.003
      Issue No: Vol. 1019 (2018)
  • Ultra-sensitive, stable isotope assisted quantification of multiple
           urinary mycotoxin exposure biomarkers
    • Authors: Bojan Šarkanj; Chibundu N. Ezekiel; Paul C. Turner; Wilfred A. Abia; Michael Rychlik; Rudolf Krska; Michael Sulyok; Benedikt Warth
      Pages: 84 - 92
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Bojan Šarkanj, Chibundu N. Ezekiel, Paul C. Turner, Wilfred A. Abia, Michael Rychlik, Rudolf Krska, Michael Sulyok, Benedikt Warth
      There is a critical need to better understand the patterns, levels and combinatory effects of exposures we are facing through our diet and environment. Mycotoxin mixtures are of particular concern due to chronic low dose exposures caused by naturally contaminated food. To facilitate new insights into their role in chronic disease, mycotoxins and their metabolites are quantified in bio-fluids as biomarkers of exposure. Here, we describe a highly sensitive urinary assay based on ultra-high performance liquid chromatography - tandem mass spectrometer (UHPLC-MS/MS) and 13C-labelled or deuterated internal standards covering the most relevant regulated and emerging mycotoxins. Utilizing enzymatic pre-treatment, solid phase extraction and UHPLC separation, the sensitivity of the method was significantly higher (10-160x lower LODs) than in a previously described method used for comparison purpose, and stable isotopes provided compensation for challenging matrix effects. This method was in-house validated and applied to re-assess mycotoxin exposure in urine samples obtained from Nigerian children, adolescent and adults, naturally exposed through their regular diet. Owing to the methods high sensitivity, biomarkers were detected in all samples. The mycoestrogen zearalenone was the most frequently detected contaminant (82%) but also ochratoxin A (76%), aflatoxin M1 (73%) and fumonisin B1 (71%) were quantified in a large share of urines. Overall, 57% of 120 urines were contaminated with both, aflatoxin M1 and fumonisin B1, and other co-exposures were frequent. These results clearly demonstrate the advanced performance of the method to assess lowest background exposures (pg mL−1 range) using a single, highly robust assay that will allow for the systematic investigation of low dose effects on human health.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.036
      Issue No: Vol. 1019 (2018)
  • Development of a general method for quantifying IgG-based therapeutic
           monoclonal antibodies in human plasma using protein G purification coupled
           with a two internal standard calibration strategy using LC-MS/MS
    • Authors: Huai-Hsuan Chiu; Hsiao-Wei Liao; Yu-Yun Shao; Yen-Shen Lu; Ching-Hung Lin; I-Lin Tsai; Ching-Hua Kuo
      Pages: 93 - 102
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Huai-Hsuan Chiu, Hsiao-Wei Liao, Yu-Yun Shao, Yen-Shen Lu, Ching-Hung Lin, I-Lin Tsai, Ching-Hua Kuo
      Monoclonal antibody (mAb) drugs have generated much interest in recent years for treating various diseases. Immunoglobulin G (IgG) represents a high percentage of mAb drugs that have been approved by the Food and Drug Administration (FDA). To facilitate therapeutic drug monitoring and pharmacokinetic/pharmacodynamic studies, we developed a general liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify the concentration of IgG-based mAbs in human plasma. Three IgG-based drugs (bevacizumab, nivolumab and pembrolizumab) were selected to demonstrate our method. Protein G beads were used for sample pretreatment due to their universal ability to trap IgG-based drugs. Surrogate peptides that were obtained after trypsin digestion were quantified by using LC-MS/MS. To calibrate sample preparation errors and matrix effects that occur during LC-MS/MS analysis, we used two internal standards (IS) method that include the IgG-based drug-IS tocilizumab and post-column infused IS. Using two internal standards was found to effectively improve quantification accuracy, which was within 15% for all mAb drugs that were tested at three different concentrations. This general method was validated in term of its precision, accuracy, linearity and sensitivity for 3 demonstration mAb drugs. The successful application of the method to clinical samples demonstrated its' applicability in clinical analysis. It is anticipated that this general method could be applied to other mAb-based drugs for use in precision medicine and clinical studies.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.040
      Issue No: Vol. 1019 (2018)
  • A high-performance electrochemical sensor for biologically meaningful
           l-cysteine based on a new nanostructured l-cysteine electrocatalyst
    • Authors: Fei Cao; Yikun Huang; Fei Wang; Dongwook Kwak; Qiuchen Dong; Donghui Song; Jie Zeng; Yu Lei
      Pages: 103 - 110
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Fei Cao, Yikun Huang, Fei Wang, Dongwook Kwak, Qiuchen Dong, Donghui Song, Jie Zeng, Yu Lei
      As a new class of l-cysteine electrocatalyst explored in this study, Au/CeO2 composite nanofibers (CNFs) were employed to modify the screen printed carbon electrode (SPCE) to fabricate a novel l-cysteine (CySH) electrochemical sensor with high performance. Its electrochemical behavior and the roles of Au and CeO2 in the composite toward electro-oxidation of CySH were elucidated and demonstrated using cyclic voltammetry and amperometry techniques for the first time through the comparison with pure CeO2 NFs. More specifically, the Au/CeO2 CNFs modified SPCE possessed greatly enhanced electrocatalytic activity toward CySH oxidation. An ultra high sensitivity of 321 μA mM−1cm−2 was obtained, which is almost 2.7 times higher than that of pure CeO2 NFs, revealing that the presence of Au imposed an important influence on the electrocatalytic activity toward CySH. The detailed reasons on such high performance were also discussed. In addition, the as-prepared sensor showed a low detection limit of 10 nM (signal to noise ratio of 3), a wide linear range up to 200 μM for the determination of CySH, an outstanding reproducibility and good long-term stability, as well as an excellent selectivity against common interferents such as tryptophan, tyrosine, methionine, ascorbic acid and uric acid. All these features indicate that the Au/CeO2 composite nanofiber is a promising candidate as a new class of l-cysteine electrocatalyst in the development of highly sensitive and selective CySH electrochemical sensor.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.048
      Issue No: Vol. 1019 (2018)
  • Rapid and low-cost strategy for detecting genome-editing induced deletion:
           A single-copy case
    • Authors: Nan Cheng; Qin Wang; Ying Shang; Yuancong Xu; Kunlun Huang; Zhansen Yang; Dengke Pan; Wentao Xu; Yunbo Luo
      Pages: 111 - 118
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Nan Cheng, Qin Wang, Ying Shang, Yuancong Xu, Kunlun Huang, Zhansen Yang, Dengke Pan, Wentao Xu, Yunbo Luo
      Genome editing techniques have been implemented in human daily lives, which has created a high demand for the development of new gene-edited product analysis methods. Conventional assays are time-consuming, labor-intensive, and costly. This paper proposes a rapid and low-cost strategy for detecting genome-editing induced deletion which works by integrating rapid-multiplex ligation-dependent probe amplification (MLPA) with a dual-lateral flow nucleic acid biosensor (LFNAB) cascade in a single-copy case. A rapid-MLPA was first introduced to the LFNAB system as a replacement for the conventional PCR for enhanced specificity and accuracy. A dual-LFNAB was applied for the detection of genome-editing induced deletion without any additional instrumentation or complex operation. After optimization, we achieved the specific detection of wildtype alleles and deletion alleles in spiked samples with a detection limit of 0.4 fM, which is comparable to that of electrophoresis-based detection assays and fluorescent biosensors. To confirm the validity and feasibility of our strategy, we assayed two pork samples from two WUZHISHAN pigs successfully. By comparing the detection results from next-generation sequencing analysis, we found that the proposed cascade demonstrates at least 20-fold shorter assay time and at least 100-fold less assay cost. To this effect, the proposed method is a rapid and low-cost solution to sample-to-answer detection of genome-editing induced deletion and shows remarkable potential in regards to international trade, transparency, and freedom of choice.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.060
      Issue No: Vol. 1019 (2018)
  • Magnetically controlled fluorescence aptasensor for simultaneous
           determination of ochratoxin A and aflatoxin B1
    • Authors: Jing Qian; Chanchan Ren; Chengquan Wang; Wei Chen; Xiaoting Lu; Henan Li; Qian Liu; Nan Hao; Huaming Li; Kun Wang
      Pages: 119 - 127
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Jing Qian, Chanchan Ren, Chengquan Wang, Wei Chen, Xiaoting Lu, Henan Li, Qian Liu, Nan Hao, Huaming Li, Kun Wang
      Development of an efficient method for the simultaneous detection of two highly concerning mycotoxins, ochratoxin A (OTA) and aflatoxin B1 (AFB1), is of great significance on food safety monitoring. Herein, a magnetically controlled fluorescence aptasensor for simultaneous determination of OTA and AFB1 has been successfully developed. The working principle of the aptasensor is based on the specific aptamer-mycotoxin recognition and further leads to the partial release of two distinguishable fluorescence labels from the magnetic carriers. Through the magnetic separation, the reporter probes in the supernatant solution can be collected and converted into a sensitive fluorescence signal with dual emission peaks. This aptasensor provided a wide detection range of 2 pg mL−1 − 5 ng mL−1 for OTA and 5 pg mL−1 − 10 ng mL−1 for AFB1. The new easy-to-wash and simple-to-use approach offers a simultaneous and high selective detection with high sensitivity (limits of detection of 0.67 and 1.70 pg mL−1 for OTA and AFB1, respectively). Remarkable accuracy (relative standard deviation < 5.6%) during the mycotoxins determination as well as excellent quantitative recoveries (95–108%) during the analysis of the spiked corn samples were also achieved. This simple aptasensing scheme provides a new avenue for high throughput screen of dual mycotoxins due to its simple manipulation, short assay times, high selectivity and sensitivity.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.063
      Issue No: Vol. 1019 (2018)
  • Ethane-bridged hybrid monoliths with well-defined mesoporosity and great
           stability for high-performance peptide separation
    • Authors: Ci Wu; Yu Liang; Zhen Liang; Lihua Zhang; Yukui Zhang
      Pages: 128 - 134
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Ci Wu, Yu Liang, Zhen Liang, Lihua Zhang, Yukui Zhang
      A novel kind of hybrid monolith with well-defined mesopore structure was prepared based on sol-gel condensation of 1, 2-bis(trimethoxysilyl)ethane (BTME) and tetramethoxysilane. Compared with terminal organosiloxanes used for preparation of conventional hybrid monoliths, BTME, as an ethane-bridged alkoxysilane precursor, could not only maintain the uniformity of pore size distribution, but also improve the chemical stability of the monolith via Si-C bonds in the framework. Owing to the controllable mesoporous structure and good stability, the monolithic column was used for the separation of peptides with half peak width less than 6 s and the run-to-run and column-to-column relative standard deviations (RSD) for the retention time of five standard peptides less than 2.5%, showing narrow peak width and good reproducibility. Moreover, the separation performance could be well maintained even after washed by the mobile phase with pH 11.0 at 50 °C. Furthermore, 100 cm-length monolithic column was prepared and successfully used for nanoRPLC-ESI-MS/MS analysis of HeLa cell lysate digests, and 5670 proteins corresponding to 37574 peptides were identified from 750 ng of the sample, showing great promising of “single-shot” large-scale in-depth proteomic research.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.033
      Issue No: Vol. 1019 (2018)
  • Recognition mechanism of aromatic derivatives resolved by argentation
           chromatography: The driving role played by substituent groups
    • Authors: Sergio Menta; Alessia Ciogli; Claudio Villani; Francesco Gasparrini; Marco Pierini
      Pages: 135 - 141
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Sergio Menta, Alessia Ciogli, Claudio Villani, Francesco Gasparrini, Marco Pierini
      Argentation chromatography is widely used nowadays as a powerful tool to separate complex mixtures of analytes containing unsaturated and/or aromatic fragments. Here we present the results of chromatographic and computational studies on a silver-thiolate stationary phase, in which the silver metal is covalently bonded to mercaptopropyl silica particles. The exceptionally high selectivity displayed by this organometallic moiety prompted us to deeply investigate its molecular recognition properties. The interactions of the silver atom with a series of benzene derivatives was investigated to gain information on the mechanism by which the different ring substituents modulate retention factors and selectivity. The experimental trend was fully rationalized by means of quantum-mechanical Density Functional Theory (DFT) calculations, which allowed us to elucidate the chromatographic results in the light of unusual and unexpected substituent effects.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.038
      Issue No: Vol. 1019 (2018)
  • Corrigendum to “New look inside human breast ducts with Raman imaging.
           Raman candidates as diagnostic markers for breast cancer prognosis:
           Mammaglobin, palmitic acid and sphingomyelin” [ACA 909, (2016) 91–100]
    • Authors: Halina Abramczyk; Beata Brozek-Pluska
      First page: 142
      Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019
      Author(s): Halina Abramczyk, Beata Brozek-Pluska

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.001
      Issue No: Vol. 1019 (2018)
  • Visualizing and studying frictional heating effects in reversed-phase
           liquid chromatography using infrared thermal imaging
    • Authors: Alexey A. Makarov; Benjamin F. Mann; Erik L. Regalado; Gregory F. Pirrone; Cheng Sun; Shuwen Sun; Timothy Nowak; Heather Wang; Ian Mangion
      Pages: 1 - 6
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Alexey A. Makarov, Benjamin F. Mann, Erik L. Regalado, Gregory F. Pirrone, Cheng Sun, Shuwen Sun, Timothy Nowak, Heather Wang, Ian Mangion
      Column temperature control is a fundamental component of liquid chromatography experiments. However, it is typically monitored indirectly by tracking the temperature of an adjacent heating element that exchanges heat with the column in a controlled environment. The practice of not directly measuring the column temperature means that uncontrolled contributions of heat, such as frictional heating inside the column, can be overlooked. The present work describes the use of a high-resolution infrared thermal imaging camera to directly measure the column heat map during mobile phase flow. The approach was used to measure the longitudinal temperature gradient formed with three common mobile phases: water, methanol, and acetonitrile, in two 50 mm reversed-phase columns, a 1.7 μm particle-packed column and a polystyrene divinylbenzene monolith. In a close approximation to an adiabatic environment, the temperature gradients (ΔT) observed with the 1.7 μm particle column at a linear velocity of 5.8 mm/s were up to +16.6 and + 12.8 °C above an ambient temperature of 23 °C for water and acetonitrile, respectively. In the case of water, the measured temperature gradient values (ΔT) were within 1% difference of theoretically-calculated values and on average within 10% for acetonitrile. By contrast, the ΔT observed in the monolith was negligible. The elevated temperatures that are generated through friction in sub-2 μm particle columns may be particularly important to consider for the design of experiments that measure structural features of temperature-sensitive analytes, such as biomolecules. While frictional heating is one important application of the thermal imaging approach described, the technique can be used to provide a data-rich profile of heat exchange in numerous experimental configurations, chromatographic or otherwise.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.061
      Issue No: Vol. 1018 (2018)
  • Lanthanide polymer labels for multiplexed determination of biomarkers in
           human serum samples by means of size exclusion chromatography-inductively
           coupled plasma mass spectrometry
    • Authors: Emma Pérez; Katarzyna Bierla; Guillermo Grindlay; Joanna Szpunar; Juan Mora; Ryszard Lobinski
      Pages: 7 - 15
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Emma Pérez, Katarzyna Bierla, Guillermo Grindlay, Joanna Szpunar, Juan Mora, Ryszard Lobinski
      Lanthanide polymer-labelled antibodies were investigated to improve the analytical figures of merit of homogeneous immunoassays with inductively coupled plasma mass spectrometry (ICP-MS) detection for multiplexed biomarker analysis in human serum samples. Specific monoclonal antibodies against four cancer biomarkers (CEA, sErbB2, CA 15.3 and CA 125) were labelled with different polymer-based lanthanide group to increase the number of metal labels per binding site. After the immunoreaction of the biomarkers with the specific antibodies, antigen-antibody complexes were separated by size-exclusion chromatography followed by ICP-MS detection. The polymer label could be loaded with 30-times more atoms of the lanthanide that the lanthanide-DOTA complex traditionally used for this purpose elsewhere [1] which resulted in a 10-fold improvement in both sensitivity and detection limits. Analytical figures of merit obtained with the lanthanide polymer labelling strategy make the detection of the biomarkers feasible below the threshold reference values used in clinical analysis. This labelling method was successfully validated by analyzing a control human serum spiked with the four biomarkers at three different concentration levels. For all the biomarkers studied, the recovery values ranged from 95% to 110% whereas inter-assay and intra-assay precision were lower than 8%. Results obtained with this approach were equivalent to those obtained by heterogenous-based immunoassays based on the detection by electro-chemiluminescence or ELISA. However, the method developed offers better analytical figures of merit using a smaller amount of sample.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.056
      Issue No: Vol. 1018 (2018)
  • Ultrasound assisted enzymatic hydrolysis for isolating titanium dioxide
           nanoparticles from bivalve mollusk before sp-ICP-MS
    • Authors: María Vanesa Taboada-López; Sara Iglesias-López; Paloma Herbello-Hermelo; Pilar Bermejo-Barrera; Antonio Moreda-Piñeiro
      Pages: 16 - 25
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): María Vanesa Taboada-López, Sara Iglesias-López, Paloma Herbello-Hermelo, Pilar Bermejo-Barrera, Antonio Moreda-Piñeiro
      Applicability of single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) using dwell times equal to or shorter than 100 μs has been tested for assessing titanium dioxide nanoparticles (TiO2 NPs) in bivalve mollusks. TiO2 NPs isolation from fresh mollusk tissues was achieved by ultrasound assisted enzymatic hydrolysis procedure using a pancreatin/lipase mixture. Optimum extraction conditions imply ultrasonication (60% amplitude) for 10 min, and 7.5 mL of a solution containing 3.0 g L−1of pancreatin and lipase (pH 7.4). The developed method was found to be repeatable (repeatability of 17% for the over-all procedure, TiO2 NPs concentration of 5.33 × 107 ± 8.89 × 106, n = 11), showing a limit of detection of 5.28 × 106 NPs g−1, and a limit of detection in size of 24.4–30.4 nm, based on the 3σ criteria, and on the 3σ/5 σ criteria, respectively. The analytical recovery within the 90–99% range (use of TiO2 NPs standards of 50 nm at 7 and 14 μg L−1 as Ti). Several bivalve mollusks (clams, cockles, mussels, razor clams, oysters and variegated scallops) were analyzed for total titanium (ICP-MS after microwave assisted acid digestion), and for TiO2 NPs by the proposed method. TiO2 NPs concentrations were within the 2.36 × 107-1.25 × 108 NPs g−1 range, and the most frequent sizes were from 50 to 70 nm.

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.075
      Issue No: Vol. 1018 (2018)
  • Nanofiber polymers as novel sorbents for on-line solid phase extraction in
           chromatographic system: A comparison with monolithic reversed phase C18
    • Authors: Martina Háková; Lucie Chocholoušová Havlíková; Jiří Chvojka; František Švec; Petr Solich; Dalibor Šatínský
      Pages: 26 - 34
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Martina Háková, Lucie Chocholoušová Havlíková, Jiří Chvojka, František Švec, Petr Solich, Dalibor Šatínský
      A novel application of nanofiber polymers in the wide area of a sample preparation techniques known as solid phase extraction has been studied. We demonstrated application of nanofibers as sorbents for use in a system including on-line extraction coupled with column-switching high performance liquid chromatography. Four types of nanofibers including polyamide 6 with two different surface densities, poly(ε-caprolactone), and polystyrene were tested. We found that three of them were very efficient extraction sorbents sufficiently stable for application in the on-line system. Our results confirmed that the extraction efficiency of the nanofibers depended on the type and chemistry of the spun polymer as well as on the fabrication process of the nanofibrous mats that affected their density, structure, surface density, and mechanical functionality. We also compared performance of all four nanofibers with a conventional monolithic reversed-phase C18 sorbent in terms of extraction efficiency using on-line solid-phase extraction-HPLC system. Polyamide 6 was found to be the best sorbent for lipophilic analytes with a retention and extraction efficiency for the target analytes comparable with that of the C18 monolith.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.065
      Issue No: Vol. 1018 (2018)
  • Synthesis and application of molecularly imprinted silica for the
           selective extraction of some polar organophosphorus pesticides from almond
    • Authors: Sara Boulanouar; Audrey Combès; Sakina Mezzache; Valérie Pichon
      Pages: 35 - 44
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Sara Boulanouar, Audrey Combès, Sakina Mezzache, Valérie Pichon
      The aim of this work was to prepare and evaluate molecularly imprinted polymers obtained by a sol-gel approach for the selective solid-phase extraction (SPE) of organophosphorus pesticides (OPs) from almond oil. The performances of molecularly imprinted silicas (MISs), prepared using different conditions of synthesis, were studied by applying different extraction procedures in order to determine the ability of the MISs to selectively extract ten target OPs. For this, the retention of OPs on MISs in pure media was compared with the retention on a non-imprinted silicas (NISs), used as control sorbent, to prove the presence of specific cavities. The most promising MIS allowed the selective extraction of the 3 most polar OPs among the 10 studied. The capacity was studied and the repeatability of the extraction recovery yield was demonstrated both in pure and real media. This MIS was able to selectively extract fenthion sulfoxide and dimethoate contained in almond oil extract after applying the optimized extraction procedure with recovery yields between 100 and 114%. The estimated limit of quantification (LOQ, S/N = 10), thanks to LC/MS analysis in MRM mode, between 1.2 and 4.6 μg/kg for those OPs in the almond fruits, was more than 10 times lower than the Maximum Residue Levels (MRLs) established by the European Commission. This MIS therefore shows a high potential for the analysis of those two polar OPs at trace levels from almond oils.

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.069
      Issue No: Vol. 1018 (2018)
  • The influence of pH on sampler uptake for an improved configuration of the
           organic-diffusive gradients in thin films passive sampler
    • Authors: Kevin M. Stroski; Jonathan K. Challis; Charles S. Wong
      Pages: 45 - 53
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Kevin M. Stroski, Jonathan K. Challis, Charles S. Wong
      Recent literature has demonstrated the utility of the organic-diffusive gradients in thin films (o-DGT) device as an effective passive sampler for polar organics in aquatic environments. Here, a new configuration comprising a polyacrylamide diffusive gel and Sepra™ ZT sorbent was developed and calibrated under multiple pH conditions. Linear uptake (r2 > 0.9) was observed at pH ≈ 5 for a suite of 31 pharmaceuticals and pesticides over 25 days, suitable for typical passive sampler deployments. At pH ≈ 8.5, linear uptake (r2 > 0.9) was observed for many of the same compounds. Comparisons of the uptake rates between the two pH experiments generally agreed (14% average relative error), with only 6 compounds exhibiting marked reduction with pH (e.g. sulfonamide antibiotics). These discrepancies may be explained by changes in analyte-sorbent interaction (H-bonding) due to speciation changes at varying pH. Samplers performed well in field evaluations conducted in an impacted river system, showing close agreement with the previously validated agarose/HLB o-DGT configuration deployed simultaneously. This work illustrates that polyacrylamide diffusive gels are a more robust and resistant outer-membrane material compared to agarose used in earlier o-DGT configurations. Sepra™ ZT binding gels served as an effective binding resin, offering a cost effective and commercially available sorbent.
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      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.074
      Issue No: Vol. 1018 (2018)
  • Highly-sensitive open-cell LA-ICPMS approaches for the quantification of
           rare earth elements in natural carbonates at parts-per-billion levels
    • Authors: Chung-Che Wu; Marcel Burger; Detlef Günther; Chuan-Chou Shen; Bodo Hattendorf
      Pages: 54 - 61
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Chung-Che Wu, Marcel Burger, Detlef Günther, Chuan-Chou Shen, Bodo Hattendorf
      This work presents a high-sensitivity approach to quantify ultra-trace concentrations of rare earth elements (REEs) in speleothem carbonates using open-cell laser ablation-sector field-inductively coupled plasma mass spectrometry (open-cell LA-SF-ICPMS). Specifically, open-cell LA in combination with a gas exchange device enabled sampling of large-scale carbonate specimens in an ambient environment. The use of a “jet” vacuum interface and the addition of small amounts of N2 gas allowed for a 20–40 fold sensitivity enhancement compared to the conventional interface configuration. Mass load effects, quantification capabilities and detection power were investigated in analyses of reference materials using various combinations of spot sizes and laser repetition rates. From a 160 μm diameter circular laser spot and 10 Hz ablation frequency, limits of detection were in the low or sub-ng g−1 range for REEs. Little dependence of Ca normalized sensitivity factors on the amount of material introduced into the plasma was observed. Relative deviations of quantified concentrations from USGS MACS-3 preferred values were smaller than 12%. The analytical approach enabled the determination of REE concentration profiles at the single digit ng g−1 level. Application to a 15-cm piece stalagmite collected from East Timor revealed at least two abrupt elevations in light rare earth elements (LREEs) within a scanning distance of 8 mm. These anomaly regions extended over a distance of ≈200 μm and showed LREE abundances elevated by at least one order of magnitude. This high-resolution open-cell LA-SF-ICPMS method has the potential to be applied in micro-domain analyses of other natural carbonates, such as travertine, tufa, and flowstones. This is promising for a better understanding of earth and environmental sciences.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.021
      Issue No: Vol. 1018 (2018)
  • Mass spectrometry profiling reveals altered plasma levels of monohydroxy
           fatty acids and related lipids in healthy humans after controlled exposure
           to biodiesel exhaust
    • Authors: Sandra Gouveia-Figueira; Masoumeh Karimpour; Jenny A. Bosson; Anders Blomberg; Jon Unosson; Maria Sehlstedt; Jamshid Pourazar; Thomas Sandström; Annelie F. Behndig; Malin L. Nording
      Pages: 62 - 69
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Sandra Gouveia-Figueira, Masoumeh Karimpour, Jenny A. Bosson, Anders Blomberg, Jon Unosson, Maria Sehlstedt, Jamshid Pourazar, Thomas Sandström, Annelie F. Behndig, Malin L. Nording
      Experimental human exposure studies are an effective tool to study adverse health effects from acute inhalation of particulate matter and other constituents of air pollution. In this randomized and double-blinded crossover study, we investigated the systemic effect on bioactive lipid metabolite levels after controlled biodiesel exhaust exposure of healthy humans and compared it to filtered air at a separate exposure occasion. Eicosanoids and other oxylipins, as well as endocannabinoids and related lipids, were quantified in plasma from 14 healthy volunteers at baseline and at three subsequent time points (2, 6, and 24 h) after 1 h exposure sessions. Protocols based on liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) methods were developed to detect temporal changes in circulating levels after biodiesel exhaust exposure. The exhaust was generated by a diesel engine fed with an undiluted rapeseed methyl ester fuel. Among the 51 analyzed lipid metabolites, PGF2α, 9,10-DiHOME, 9-HODE, 5-HETE, 11-HETE, 12-HETE, and DEA displayed significant responsiveness to the biodiesel exhaust exposure as opposed to filtered air. Of these, 9-HODE and 5-HETE at 24 h survived the 10% false discovery rate cutoff (p < 0.003). Hence, the majority of the responsive lipid metabolites were monohydroxy fatty acids. We conclude that it is possible to detect alterations in circulating bioactive lipid metabolites in response to biodiesel exhaust exposure using LC-MS/MS, with emphasis on metabolites with inflammation related properties and implications on cardiovascular health and disease. These observations aid future investigations on air pollution effects, especially with regard to cardiovascular outcomes.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.032
      Issue No: Vol. 1018 (2018)
  • Plasma-assisted alignment in the fabrication of microchannel-array-based
           in-tube solid-phase microextraction microchips packed with TiO2
           nanoparticles for phosphopeptide analysis
    • Authors: Siyu Wang; Xiayan Wang; Lin Wang; Qiaosheng Pu; Wenbin Du; Guangsheng Guo
      Pages: 70 - 77
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Siyu Wang, Xiayan Wang, Lin Wang, Qiaosheng Pu, Wenbin Du, Guangsheng Guo
      Phosphorylated peptides are important for understanding the processes of biological regulation. However, the detection of phosphopeptides remains a challenge because of their low abundance and the suppression by non-phosphopeptides. Here, we report a strategy for the facile and rapid fabrication of TiO2-nanoparticle-packed microchannel-array glass microchips (TMA-microchips) for in-tube solid-phase microextraction (IT-SPME) using a plasma-assisted method for the precise alignment of the microstructure. This proposed strategy was applied to the selective enrichment of phosphopeptides from a protein digestion mixture, demonstrating the high capacity and selectivity of the SPME microchips. An important feature of this array design is that it fully exploits the advantage of nanoparticles for improving extraction capacity and simultaneously provides an effective way to reduce the pressure for driving solutions; thus, it paves the way for future methods that simultaneously take advantage of nanomaterials and microchips.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.018
      Issue No: Vol. 1018 (2018)
  • Equipment-free nucleic acid extraction and amplification on a simple paper
           disc for point-of-care diagnosis of rotavirus A
    • Authors: Xin Ye; Jin Xu; Lijuan Lu; Xinxin Li; Xueen Fang; Jilie Kong
      Pages: 78 - 85
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Xin Ye, Jin Xu, Lijuan Lu, Xinxin Li, Xueen Fang, Jilie Kong
      The use of paper-based methods for clinical diagnostics is a rapidly expanding research topic attracting a great deal of interest. Some groups have attempted to realize an integrated nucleic acid test on a single microfluidic paper chip, including extraction, amplification, and readout functions. However, these studies were not able to overcome complex modification and fabrication requirements, long turn-around times, or the need for sophisticated equipment like pumps, thermal cyclers, or centrifuges. Here, we report an extremely simple paper-based test for the point-of-care diagnosis of rotavirus A, one of the most common pathogens that causes pediatric gastroenteritis. This paper-based test could perform nucleic acid extraction within 5 min, then took 25 min to amplify the target sequence, and the result was visible to the naked eye immediately afterward or quantitative by the UV–Vis absorbance. This low-cost method does not require extra equipment and is easy to use either in a lab or at the point-of-care. The detection limit for rotavirus A was found to be 1 × 103 copies/mL. In addition, 100% sensitivity and specificity were achieved when testing 48 clinical stool samples. In conclusion, the present paper-based test fulfills the main requirements for a point-of-care diagnostic tool, and has the potential to be applied to disease prevention, control, and precision diagnosis.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.068
      Issue No: Vol. 1018 (2018)
  • A sensitive colorimetric aptasensor based on trivalent peroxidase-mimic
           DNAzyme and magnetic nanoparticles
    • Authors: Shuwen Liu; Naihan Xu; Chunyan Tan; Wei Fang; Ying Tan; Yuyang Jiang
      Pages: 86 - 93
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Shuwen Liu, Naihan Xu, Chunyan Tan, Wei Fang, Ying Tan, Yuyang Jiang
      In this study, a novel colorimetric aptasensor was prepared by coupling trivalent peroxidase-mimic DNAzyme and magnetic nanoparticles for highly sensitive and selective detection of target proteins. A three G-quadruplex (G4) DNA-hemin complex was employed as the trivalent peroxidase-mimic DNAzyme, in which hemin assisted the G4-DNA to fold into a catalytic conformation and act as an enzyme. The design of the aptasensor includes magnetic nanoparticles (MNPs), complementary DNA (cDNA) modified with biotin, and a label-free single strand DNA (ssDNA) including the aptamer and trivalent peroxidase-mimic DNAzyme. The trivalent DNAzyme, which has the highest catalytic activity among multivalent DNAzymes, catalyzed the H2O2-mediated oxidation of ABTS. The colorless ABTS was oxidized to produce a blue-green product that can be clearly distinguished by the naked eye. The aptamer and trivalent peroxidase-mimic DNAzyme promote the specificity and sensitivity of this detection method, which can be generalized for other targets by simply replacing the corresponding aptamers. To demonstrate the feasible use of the aptasensor for target detection, a well-known tumor biomarker MUC1 was evaluated as the model target. The limits of detection were determined to be 5.08 and 5.60 nM in a linear range of 50–1000 nM in a buffer solution and 10% serum system, respectively. This colorimetric and label-free aptasensor with excellent sensitivity and strong anti-interference ability has potential application in disease diagnoses, prognosis tracking, and therapeutic evaluation.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.01.040
      Issue No: Vol. 1018 (2018)
  • AuNS@Ag core-shell nanocubes grafted with rhodamine for concurrent
           metal-enhanced fluorescence and surfaced enhanced Raman determination of
           mercury ions
    • Authors: Huanhuan Li; Quansheng Chen; Md Mehedi Hassan; Qin Ouyang; Tianhui Jiao; Yi Xu; Min Chen
      Pages: 94 - 103
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Huanhuan Li, Quansheng Chen, Md Mehedi Hassan, Qin Ouyang, Tianhui Jiao, Yi Xu, Min Chen
      Mercury ion (Hg2+) is a highly hazardous and widespread pollutant with bio-accumulative properties. Although the existing Hg2+ detection methods have high sensitivity and reliability, whereas there have few reports concerning bimodal detection for Hg2+ with one sensor. Toward this goal, a novel sensor based on rhodamine derivatives (RhD) grafted AuNS@Ag core-shell nanocubes (CSN) has been synthesized and shown the bimodal detection capabilities with metal enhanced fluorescence (MEF) and surface enhanced Raman scattering (SERS) for Hg2+. Herein, resultant CSN acts as the signal enhancing material; RhD was modified on the outside of the shell to ensure the signal sensitive of the CSN-RhD hybrids. In this work, we investigate the size- and shape-dependent SERS activity of plasmonic CSN comprised of AuNS as cores and Ag cuboids as shells. The SERS activity of CSN with spherical core was found to increase with the increasing thickness of the Ag cubic shell. Sequel, under an optimized condition, a display of strong MEF and SERS signals of the resulting mixtures with increasing of Hg2+ concentrations was observed. The proposed bimodal sensor showed excellent performances for Hg2+ along with wide linear range of 0.001–1000 ppm and 0.01–1000 ppm as well as the relatively low detection limit of 0.94 and 5.16 ppb for MEF and SERS assays, respectively. Furthermore, the ability of the sensor to detect Hg2+was also confirmed in adulterated milk samples.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.01.050
      Issue No: Vol. 1018 (2018)
  • Reaction-based SERS nanosensor for monitoring and imaging the endogenous
           hypochlorous acid in living cells
    • Authors: Da-Wei Li; Jia-Jia Sun; Zhen-Fei Gan; Hua-Ying Chen; Dan Guo
      Pages: 104 - 110
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Da-Wei Li, Jia-Jia Sun, Zhen-Fei Gan, Hua-Ying Chen, Dan Guo
      Hypochlorous acid (HOCl), as an important reactive oxygen species (ROS), is involved with many pathological and physiological pathways, whereas many aspects of its roles remain unclear due to the lack of robust analytical methods. In this work, we report a novel kind of special reaction-based nanosensors, gold nanoparticles modified with newly synthesized 2-mercapto-4-methoxy-phenol molecules (AuNPs/MMP), to detect the endogenous HOCl in living cells according to the changes in the SERS spectrum of AuNPs/MMP resulting from the reaction of HOCl with MMP on AuNPs. These nanosensors can rapidly respond to HOCl within 1 min with the detection limit at 10−7 M level. Furthermore, the nanosensors exhibit high selectivity for HOCl because of the specificity of the reaction combined with the fingerprinting capability of SERS. Consequently, the proposed SERS nanosensors are capable of monitoring and imaging the endogenous HOCl generated in a living macrophage under stimulation, showing great promise to be used for in-situ studies of the pathophysiological processes that involve HOCl.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.023
      Issue No: Vol. 1018 (2018)
  • Solid phase microextraction with poly(deep eutectic solvent) monolithic
           column online coupled to HPLC for determination of non-steroidal
           anti-inflammatory drugs
    • Authors: Rong Wang; Wenqing Li; Zilin Chen
      Pages: 111 - 118
      Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018
      Author(s): Rong Wang, Wenqing Li, Zilin Chen
      Polymer monolithic column based on a green deep eutectic solvent (DES) was prepared for in-tube solid phase microextraction of non-steroidal anti-inflammatory drugs (NSAIDs) in aqueous samples. DES composed of choline chloride and itaconic acid was adopted as functional monomer to synthesize a polymeric monolith inside polydopamine-functionalized poly(ether ether ketone) (PEEK) tube. The obtained monolithic column was characterized with fourier transform infrared spectrometry, X-ray photoelectron spectrometer and field emission scanning electron microscope. An online SPME-HPLC method was developed by connecting the PEEK tube to the HPLC system. Parameters including sampling rate, desorption time, sample pH value and sample volume that can affect the performance of this method were investigated. Under the optimized conditions, the proposed SPME-HPLC method showed high extraction efficiency (enrichment factors about 100), good linearity (R ≥ 0.9997) and good reproducibility (relative standard deviation < 4.32%) for determination of three NSAIDs in aqueous solution. The limits of quantification were found to be in a range of 0.05–0.25 ng mL−1. The SPME-HPLC method was also successfully applied to detect NSAIDs in lake water and human plasma samples.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
      DOI: 10.1016/j.aca.2018.02.024
      Issue No: Vol. 1018 (2018)
  • Outside Front Cover
    • Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020

      PubDate: 2018-04-15T14:38:40Z
  • Aerosol sampler for analysis of fine and ultrafine aerosols
    • Authors: Pavel
      Abstract: Publication date: 22 August 2018
      Source:Analytica Chimica Acta, Volume 1020
      Author(s): Pavel Mikuška, Lukáš Čapka, Zbyněk Večeřa
      A new aerosol sampler based on the original version of Aerosol Counterflow Two-Jets Unit (ACTJU) is described. The ACTJU collector, connected with a water-based Condensation Growth Unit (CGU) placed upstream of the ACTJU, accomplished the quantitative collection of fine and ultrafine aerosol particles down to a few nanometers in diameter. Condensation of water vapor in the CGU enlarges nanometer sized particles to larger sizes in the supermicrometer range and the formed droplets are then collected into water in the ACTJU collector. The continuous collection of aerosols with the CGU-ACTJU sampler allows for the time-resolved measurement of changes in the concentration of particulate constituents. Coupling of the CGU-ACTJU sampler with on-line detection devices allows in-situ automated analysis of water-soluble aerosol components with high time resolution of 1 s (e.g., FIA detection for nitrite or nitrate) or 1 h (e.g., IC detection with preconcentration step for inorganic anions). Under the optimum conditions (the air flow rate of 10 L min−1 and water flow rate of 1.5 mL min−1), the limit of detection (IC including the preconcentration) for particulate fluoride, chloride, nitrite, nitrate, sulphate and phosphate is 2.53, 6.64, 24.2, 16.8, 0.12 and 5.03 ng m−3, respectively. The apparatus is sufficiently robust for its application at routine monitoring of aerosol composition in real-time.
      Graphical abstract image

      PubDate: 2018-04-15T14:38:40Z
  • Outside Front Cover
    • Abstract: Publication date: 17 August 2018
      Source:Analytica Chimica Acta, Volume 1019

      PubDate: 2018-04-15T14:38:40Z
  • Outside Front Cover
    • Abstract: Publication date: 14 August 2018
      Source:Analytica Chimica Acta, Volume 1018

      PubDate: 2018-04-15T14:38:40Z
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Heriot-Watt University
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