The Experts below are selected from a list of 49353 Experts worldwide ranked by ideXlab platform
Gary J Van Berkel - One of the best experts on this subject based on the ideXlab platform.
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Thin Layer Chromatography desorption electrospray ionization mass spectrometry investigation of goldenseal alkaloids
Analytical Chemistry, 2007Co-Authors: Gary J Van Berkel, Bruce A Tomkins, Vilmos KerteszAbstract:Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase Thin-Layer Chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cm × 10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed Rf value across the plates versus the stationary desorption electrospray emitter. Goldenseal (Hydrastis canadensis) and related alkaloids and commercial dietary supplements were used as standards and samples. Alkaloid standards and samples were spotted and separated on aluminum- or glass-backed plates using established literature methods. The mass spectral signal levels as a function of desorption spray solvent were investigated with acetonitrile pro...
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quantitative Thin Layer Chromatography mass spectrometry analysis of caffeine using a surface sampling probe electrospray ionization tandem mass spectrometry system
Analytical Chemistry, 2005Co-Authors: Michael Ford, Michael A Deibel, Bruce A Tomkins, Gary J Van BerkelAbstract:Quantitative determination of caffeine on reversed-phase C8 Thin-Layer Chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The Thin-Layer Chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 μm/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and Thin-Layer Chromatography/electrospray tandem mass spectrometry methods determined from the calibration curve statistics were 0.20 ng injected (0.50 μL) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three die...
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Thin Layer Chromatography and mass spectrometry coupled using desorption electrospray ionization
Analytical Chemistry, 2005Co-Authors: Gary J Van Berkel, Michael J Ford, Michael A DeibelAbstract:Desorption electrospray ionization (DESI) was demonstrated as a means to couple Thin-Layer Chromatography (TLC) with mass spectrometry. The experimental setup and its optimization are described. Development lanes were scanned by moving the TLC plate under computer control while directing the stationary DESI emitter charged droplet plume at the TLC plate surface. Mass spectral data were recorded in either selected reaction monitoring mode or in full scan ion trap mode using a hybrid triple quadrupole linear ion trap mass spectrometer. Fundamentals and practical applications of the technique were demonstrated in positive ion mode using selected reaction monitoring detection of rhodamine dyes separated on hydrophobic reversed-phase C8 plates and reversed-phase C2 plates, in negative ion full scan mode using a selection of FD&C dyes separated on a wettable reversed-phase C18 plate, and in positive ion full scan mode using a mixture of aspirin, acetaminophen, and caffeine from an over-the-counter pain medicati...
Michael A Deibel - One of the best experts on this subject based on the ideXlab platform.
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quantitative Thin Layer Chromatography mass spectrometry analysis of caffeine using a surface sampling probe electrospray ionization tandem mass spectrometry system
Analytical Chemistry, 2005Co-Authors: Michael Ford, Michael A Deibel, Bruce A Tomkins, Gary J Van BerkelAbstract:Quantitative determination of caffeine on reversed-phase C8 Thin-Layer Chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The Thin-Layer Chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 μm/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and Thin-Layer Chromatography/electrospray tandem mass spectrometry methods determined from the calibration curve statistics were 0.20 ng injected (0.50 μL) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three die...
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Thin Layer Chromatography and mass spectrometry coupled using desorption electrospray ionization
Analytical Chemistry, 2005Co-Authors: Gary J Van Berkel, Michael J Ford, Michael A DeibelAbstract:Desorption electrospray ionization (DESI) was demonstrated as a means to couple Thin-Layer Chromatography (TLC) with mass spectrometry. The experimental setup and its optimization are described. Development lanes were scanned by moving the TLC plate under computer control while directing the stationary DESI emitter charged droplet plume at the TLC plate surface. Mass spectral data were recorded in either selected reaction monitoring mode or in full scan ion trap mode using a hybrid triple quadrupole linear ion trap mass spectrometer. Fundamentals and practical applications of the technique were demonstrated in positive ion mode using selected reaction monitoring detection of rhodamine dyes separated on hydrophobic reversed-phase C8 plates and reversed-phase C2 plates, in negative ion full scan mode using a selection of FD&C dyes separated on a wettable reversed-phase C18 plate, and in positive ion full scan mode using a mixture of aspirin, acetaminophen, and caffeine from an over-the-counter pain medicati...
Peter Collins - One of the best experts on this subject based on the ideXlab platform.
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dynamics of bitumen fractions by Thin Layer Chromatography flame ionization detection
Energy & Fuels, 2001Co-Authors: J F Masson, Terry Price, Peter CollinsAbstract:Thin-Layer Chromatography/flame ionization detection (TLC/FID) allows for the fractionation of bitumen into four fractions, namely, the saturates, the aromatics, the resins A and the resins B (SARAB). The technique is rapid and economical, but it lacks reproducibility. The effect of chromarod aging on reproducibility was investigated along with that of the time between bitumen dissolution and its analysis (time lapse effects). It is found that chromarod aging causes a 2−5% variation in SARAB content, and that time lapse causes a 50−75% variation in the aromatics and resins A content. The effect of time lapse stems from the aging of bitumen in solution. A mechanism for this aging is provided. It is demonstrated to be a physical rather than a chemical transformation of bitumen that reveals itself as a conversion of aromatics into resins. The physical nature of aging is shown by the absence of oxidation and aromatization in solution and by the successful modeling of aging after a reversible process. The conv...
Bruce A Tomkins - One of the best experts on this subject based on the ideXlab platform.
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Thin Layer Chromatography desorption electrospray ionization mass spectrometry investigation of goldenseal alkaloids
Analytical Chemistry, 2007Co-Authors: Gary J Van Berkel, Bruce A Tomkins, Vilmos KerteszAbstract:Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase Thin-Layer Chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cm × 10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed Rf value across the plates versus the stationary desorption electrospray emitter. Goldenseal (Hydrastis canadensis) and related alkaloids and commercial dietary supplements were used as standards and samples. Alkaloid standards and samples were spotted and separated on aluminum- or glass-backed plates using established literature methods. The mass spectral signal levels as a function of desorption spray solvent were investigated with acetonitrile pro...
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quantitative Thin Layer Chromatography mass spectrometry analysis of caffeine using a surface sampling probe electrospray ionization tandem mass spectrometry system
Analytical Chemistry, 2005Co-Authors: Michael Ford, Michael A Deibel, Bruce A Tomkins, Gary J Van BerkelAbstract:Quantitative determination of caffeine on reversed-phase C8 Thin-Layer Chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The Thin-Layer Chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 μm/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and Thin-Layer Chromatography/electrospray tandem mass spectrometry methods determined from the calibration curve statistics were 0.20 ng injected (0.50 μL) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three die...
Vilmos Kertesz - One of the best experts on this subject based on the ideXlab platform.
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Thin Layer Chromatography desorption electrospray ionization mass spectrometry investigation of goldenseal alkaloids
Analytical Chemistry, 2007Co-Authors: Gary J Van Berkel, Bruce A Tomkins, Vilmos KerteszAbstract:Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase Thin-Layer Chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cm × 10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed Rf value across the plates versus the stationary desorption electrospray emitter. Goldenseal (Hydrastis canadensis) and related alkaloids and commercial dietary supplements were used as standards and samples. Alkaloid standards and samples were spotted and separated on aluminum- or glass-backed plates using established literature methods. The mass spectral signal levels as a function of desorption spray solvent were investigated with acetonitrile pro...
