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You searched for: Subject gases Remove constraint Subject: gases Subject term caffeine Remove constraint Subject term: caffeine
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1. A rapid method for the assay of methylxanthines alkaloids: Theobromine, theophylline and caffeine, in cocoa products and drugs by paper spray tandem mass spectrometry

Author:
Lucia Bartella; Leonardo Di Donna; Anna Napoli; Carlo Siciliano; Giovanni Sindona; Fabio Mazzotti
Source:
Food chemistry 2019 v.278 pp. 261-266
ISSN:
0308-8146
Subject:
caffeine; gases; theophylline; cocoa products; ions; theobromine; high performance liquid chromatography; rapid methods; paper; tandem mass spectrometry; solvents
Abstract:
... A fast method for the determination of methylxanthines in cocoa products and drugs based on PS-MS/MS under MRM condition has been developed. Analyte ions were generated by applying a high voltage on a paper substrate drenched of sample extract using a small volume (∼15 μL) of spray solvent. The gas phase chemistry of the molecules under investigation has been elucidated. The accuracy values of the ...
DOI:
10.1016/j.foodchem.2018.11.072

2. Caffeine and glucosamine mobility shifts by adduction with 2‐butanol depended on interaction energy, charge delocalization, and steric hindrance in ion mobility spectrometry

Author:
Dairo Meza‐Morelos; Roberto Fernandez‐Maestre
Source:
Journal of mass spectrometry 2017 v.52 no.12 pp. 823-829
ISSN:
1076-5174
Subject:
caffeine; electric field; energy; gases; glucosamine; hydrogen bonding; ions; lactic acid; mass spectrometry; nitrogen
Abstract:
... Ion mobility spectrometry (IMS) is an analytical technique that separates gas‐phase ions drifting under an electric field according to their size to charge ratio. We used electrospray ionization‐drift tube IMS coupled to quadrupole mass spectrometry to measure the mobilities of glucosamine (GH⁺) and caffeine (CH⁺) ions in pure nitrogen or when the shift reagent (SR) 2‐butanol was introduced in the ...
DOI:
10.1002/jms.4026

3. 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

4. Direct coupling of packed column supercritical fluid chromatography to continuous corona discharge ion mobility spectrometry

Author:
A. Rahmanian; H.S. Ghaziaskar; T. Khayamian
Source:
Journal of chromatography 2013 v.1272 no. pp. 126-131
ISSN:
0021-9673
Subject:
caffeine; carbon dioxide; detectors; electrodes; freezing; gases; ionization; medroxyprogesterone; methanol; spectroscopy; supercritical fluid chromatography; testosterone; theophylline
Abstract:
... In this study, packed column supercritical fluid chromatography (SFC) was directly coupled to a continuous corona discharge (CD) ion mobility spectrometer (IMS) with several modifications. The main advantage of the developed detector is its capability to introduce full column effluent up to 2000mLmin⁻¹ CO₂ gas directly into the IMS cell relative to 40mLmin⁻¹ CO₂ gas as a maximum tolerance, reporte ...
DOI:
10.1016/j.chroma.2012.11.063

5. Looking into individual coffee beans during the roasting process: direct micro-probe sampling on-line photo-ionisation mass spectrometric analysis of coffee roasting gases

Author:
Romy Hertz-Schünemann; Thorsten Streibel; Sven Ehlert; Ralf Zimmermann
Source:
Analytical and bioanalytical chemistry 2013 v.405 no.22 pp. 7083-7096
ISSN:
1618-2642
Subject:
Coffea arabica; Coffea canephora; caffeine; coffee beans; cultivars; flavor compounds; gases; ionization; lipids; mass spectrometry; multivariate analysis; phenol; roasting; temporal variation; volatile organic compounds
Abstract:
... A micro-probe (μ-probe) gas sampling device for on-line analysis of gases evolving in confined, small objects by single-photon ionisation time-of-flight mass spectrometry (SPI-TOFMS) was developed. The technique is applied for the first time in a feasibility study to record the formation of volatile and flavour compounds during the roasting process within (inside) or in the direct vicinity (outsid ...
DOI:
10.1007/s00216-013-7006-y

6. Rapid Evaluation of Suitable Substrates with High Affinity to Artificial Caffeine Receptors by MS Based Techniques

Author:
Daniela Mirk; Heinrich Luftmann; Siegfried R. Waldvogel
Source:
Zeitschrift für Naturforschung 2014 v.60 no.10 pp. 1077-1082
ISSN:
0932-0776
Subject:
binding capacity; caffeine; dissociation; gases; receptors; tandem mass spectrometry
Abstract:
... A modification of our triphenylene ketal based receptor facilitates electrospray tandem mass spectrometry investigations. Binding affinities of eleven potential substrates, e.g. caffeine and other xanthine alkaloids, are probed in the gas phase with collision induced dissociation. The relative stabilities of the substrate-receptor complexes are rapidly determined and the findings are correlated wi ...
DOI:
10.1515/znb-2005-1010

7. Simultaneous Determination of Seven Adulterants in Slimming Functional Foods by HPLC–ESI–MS/MS

Author:
Yang Li; Jiangtao Hu; Ying Shi; Aimin Sun; Chengjun Sun
Source:
Food analytical methods 2011 v.4 no.4 pp. 505-516
ISSN:
1936-9751
Subject:
adulterated products; caffeine; clenbuterol; correlation; detection limit; ethers; fenfluramine; formic acid; functional foods; gases; mass spectrometry; methanol; nitrogen; powders; sodium sulfate; strychnine
Abstract:
... A high-performance liquid chromatography–electrospray ionization–tandem mass spectrometric method for simultaneous determination of seven adulterants including pseudoephedrine, norpseudoephedrine, caffeine, strychnine, fenfluramine, sildenafil, and amfepramone in slimming functional foods was established. For tablet formulation, the target chemicals were extracted with ammoniated methanol, while f ...
DOI:
10.1007/s12161-010-9192-y