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You searched for: Journal Analytical chemistry Remove constraint Journal: Analytical chemistry Publication Year 2015 Remove constraint Publication Year: 2015 Subject caffeine Remove constraint Subject: caffeine
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1. Miniature Flow-Through Low-Temperature Plasma Ionization Source for Ambient Ionization of Gases and Aerosols

Author:
Spencer Sandra E.; Santiago Brandon G.; Glish Gary L.
Source:
Analytical chemistry 2015 v.87 no.23 pp. 11887-11892
ISSN:
1520-6882
Subject:
aerosols; caffeine; cellulose; gases; ionization; ions; pyrolysis
Abstract:
... The design and operation of an inexpensive, miniature low-temperature plasma ion source is detailed. The miniature low-temperature plasma ion source is operated in a “flow-through” configuration, wherein the gaseous or aerosolized analyte, caffeine or pyrolyzed ethyl cellulose, in a carrier gas is used as the plasma gas. In this flow-through configuration, the sensitivity for the caffeine standard ...
DOI:
10.1021/acs.analchem.5b03447

2. New Microfluidic-Based Sampling Procedure for Overcoming the Hematocrit Problem Associated with Dried Blood Spot Analysis

Author:
Leuthold Luc Alexis; Heudi Olivier; Déglon Julien; Raccuglia Marc; Augsburger Marc; Picard Franck; Kretz Olivier; Thomas Aurélien
Source:
Analytical chemistry 2015 v.87 no.4 pp. 2068-2071
ISSN:
1520-6882
Subject:
blood; blood viscosity; blood volume; caffeine; hematocrit; in vitro studies
Abstract:
... Hematocrit (Hct) is one of the most critical issues associated with the bioanalytical methods used for dried blood spot (DBS) sample analysis. Because Hct determines the viscosity of blood, it may affect the spreading of blood onto the filter paper. Hence, accurate quantitative data can only be obtained if the size of the paper filter extracted contains a fixed blood volume. We describe for the fi ...
DOI:
10.1021/ac503931g

3. On-Line Hydrogen-Isotope Measurements of Organic Samples Using Elemental Chromium: An Extension for High Temperature Elemental-Analyzer Techniques

Author:
Gehre Matthias; Renpenning Julian; Gilevska Tetyana; Qi Haiping; Coplen Tyler B.; Meijer Harro A. J.; Brand Willi A.; Schimmelmann Arndt
Source:
Analytical chemistry 2015 v.87 no.10 pp. 5198-5205
ISSN:
1520-6882
Subject:
caffeine; carbon; chlorine; chromium; deuterium; helium; hydrochloric acid; hydrogen cyanide; isotope fractionation; mass spectrometry; nitrogen; organic matter; silver; stable isotopes; temperature; water analysis; Antarctic region
Abstract:
... The high temperature conversion (HTC) technique using an elemental analyzer with a glassy carbon tube and filling (temperature conversion/elemental analysis, TC/EA) is a widely used method for hydrogen isotopic analysis of water and many solid and liquid organic samples with analysis by isotope-ratio mass spectrometry (IRMS). However, the TC/EA IRMS method may produce inaccurate δ²H results, with ...
DOI:
10.1021/acs.analchem.5b00085

4. Position-Specific Isotope Analysis of Xanthines: A 13C Nuclear Magnetic Resonance Method to Determine the 13C Intramolecular Composition at Natural Abundance

Author:
Diomande Didier G.; Martineau Estelle; Gilbert Alexis; Nun Pierrick; Murata Ariaki; Yamada Keita; Watanabe Naoharu; Tea Illa; Robins Richard J.; Yoshida Naohiro; Remaud Gérald S.
Source:
Analytical chemistry 2015 v.87 no.13 pp. 6600-6606
ISSN:
1520-6882
Subject:
beverages; caffeine; flavor; isotope fractionation; mass spectrometry; monitoring; nuclear magnetic resonance spectroscopy; solubility; stable isotopes; tea; theobromine; theophylline
Abstract:
... The natural xanthines caffeine, theobromine, and theophylline are of major commercial importance as flavor constituents in coffee, cocoa, tea, and a number of other beverages. However, their exploitation for authenticity, a requirement in these commodities that have a large origin-based price-range, by the standard method of isotope ratio monitoring by mass spectrometry (irm-MS) is limited. We hav ...
DOI:
10.1021/acs.analchem.5b00559