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Rodinei Augusti - One of the best experts on this subject based on the ideXlab platform.
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Cyclization reactions of acylium and thioacylium ions with Isocyanates and isothiocyanates: Gas phase synthesis of 3,4-dihydro-2,4-dioxo-2H-1,3,5-oxadiazinium ions
Journal of the American Society for Mass Spectrometry, 2005Co-Authors: Eduardo C. Meurer, Regina Sparrapan, Daniela M. Tomazela, Marcos N. Eberlin, Rodinei AugustiAbstract:Gas-phase reactions of several acylium and thioacylium ions, that is H_2C=N-C^+=O, H_2C=N-C^+=S, O=C=N-C^+=O, S=C=N-C^+=O, H_3C-C^+=O, and (CH_3)_2N-C^+=O, with both a model Isocyanate and isothiocyanate, that is, C_2H_5-N=C=O and C_2H_5-N=C=S, were investigated using tandem-in-space pentaquadrupole mass spectrometry. In these reactions, the formation of mono- and double-addition products is observed concurrently with proton transfer products. The double-addition products are far more favored in reactions with Ethyl Isocyanate, whereas the reactions with Ethyl isothiocyanate form, preferentially, either the mono-addition product or proton transfer products, or both. Retro-addition dominates the low-energy collision-induced dissociation of the mono- and double-addition products with reformation of the corresponding reactant ions. Ab initio calculations at Becke3LYP//6-311 + G(d,p) level indicate that cyclization is favored for the double-addition products and that products equivalent to those synthesized in solution, that is, of 3,4-dihydro-2,4-dioxo-2H-1,3,5-oxadiazinium ions and sulfur analogs, are formed.
Masatoshi Yamaguchi - One of the best experts on this subject based on the ideXlab platform.
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fully automated reagent peak free liquid chromatography fluorescence analysis of highly polar carboxylic acids using a column switching system and fluorous scavenging derivatization
IEEE Journal of Solid-state Circuits, 2013Co-Authors: Kenichiro Todoroki, Hiroki Hashimoto, Kazuyuki Machida, Miki Itoyama, Tadashi Hayama, Hideyuki Yoshida, Hitoshi Nohta, Manabu Nakashima, Masatoshi YamaguchiAbstract:In this study, we combined a column-switching system with a fluorous scavenging derivatization method to develop a fully automated reagent peak-free LC fluorescence detection protocol for the analysis of highly polar carboxylic acids. In this method, highly polar carboxylic acids were derivatized with fluorescent 1-pyrenemEthylamine in the presence of 1-Ethyl-3-(3-dimEthylaminopropyl)carbodiimide and 1-hydroxy-1H-benzotriazole. Residual excess of the unreacted reagent was tagged with 2-(perfluorooctyl)Ethyl Isocyanate and then removed selectively using a fluorous column-switching system placed in front of an analytical reversed-phase column. The signal of the fluorous-tagged unreacted reagent was completely absent in the resulting chromatograms; therefore, it did not interfere with the quantification of each acid especially those eluted before 20 min. The detection limits (S/N = 3) for the examined acids were in the range from 4.0 to 22 fmol per injection. We have applied this method to comparative analysis of highly polar carboxylic acids in urine samples obtained from diabetes mellitus type-II model mice and their control.
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reagent peak free liquid chromatography fluorescence analysis of carboxylic acids using a fluorous scavenging derivatization method
Analytical and Bioanalytical Chemistry, 2010Co-Authors: Kenichiro Todoroki, Hiroki Hashimoto, Miki Itoyama, Tadashi Hayama, Hideyuki Yoshida, Hitoshi Nohta, Tomohiko Mikawa, Eijiro Kojima, Masatoshi YamaguchiAbstract:We developed a fluorous scavenging-derivatization method for reagent peak-free liquid chromatography (LC)-fluorescence analysis of carboxylic acids. In this method, carboxylic acids were fluorescently derivatized with 1-pyrenemEthylamine in the presence of 1-Ethyl-3-(3-dimEthylaminopropyl)carbodiimide and 1-hydroxy-1H-benzotriazole. Residual excess unreacted reagent was tagged with 2-(perfluorooctyl)Ethyl Isocyanate and could be selectively removed by microfluorous solid-phase extraction before LC analysis. With use of this method, eight fluorescent derivatives of linear aliphatic carboxylic acids (C(1)-C(8)) can be separated within 30 min by reversed-phase LC with gradient elution. In the chromatogram obtained, the fluorous-tagged unreacted reagent peak is greatly decreased after microfluorous solid-phase extraction and does not interfere with the quantification of each acid. With use of microfluorous solid-phase extraction with 80% (v/v) aqueous methanol elution, over 99.9% of the unreacted fluorescent reagent was removed. The detection limits (signal-to-noise ratio of 3) for the carboxylic acids examined are 2.3-8.0 fmol per 10-microL injection. We also applied this method successfully to the analysis of highly polar carboxylic acids such as alpha-keto acids and tricarboxylic acid cycle metabolites.
Kenichiro Todoroki - One of the best experts on this subject based on the ideXlab platform.
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fully automated reagent peak free liquid chromatography fluorescence analysis of highly polar carboxylic acids using a column switching system and fluorous scavenging derivatization
IEEE Journal of Solid-state Circuits, 2013Co-Authors: Kenichiro Todoroki, Hiroki Hashimoto, Kazuyuki Machida, Miki Itoyama, Tadashi Hayama, Hideyuki Yoshida, Hitoshi Nohta, Manabu Nakashima, Masatoshi YamaguchiAbstract:In this study, we combined a column-switching system with a fluorous scavenging derivatization method to develop a fully automated reagent peak-free LC fluorescence detection protocol for the analysis of highly polar carboxylic acids. In this method, highly polar carboxylic acids were derivatized with fluorescent 1-pyrenemEthylamine in the presence of 1-Ethyl-3-(3-dimEthylaminopropyl)carbodiimide and 1-hydroxy-1H-benzotriazole. Residual excess of the unreacted reagent was tagged with 2-(perfluorooctyl)Ethyl Isocyanate and then removed selectively using a fluorous column-switching system placed in front of an analytical reversed-phase column. The signal of the fluorous-tagged unreacted reagent was completely absent in the resulting chromatograms; therefore, it did not interfere with the quantification of each acid especially those eluted before 20 min. The detection limits (S/N = 3) for the examined acids were in the range from 4.0 to 22 fmol per injection. We have applied this method to comparative analysis of highly polar carboxylic acids in urine samples obtained from diabetes mellitus type-II model mice and their control.
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reagent peak free liquid chromatography fluorescence analysis of carboxylic acids using a fluorous scavenging derivatization method
Analytical and Bioanalytical Chemistry, 2010Co-Authors: Kenichiro Todoroki, Hiroki Hashimoto, Miki Itoyama, Tadashi Hayama, Hideyuki Yoshida, Hitoshi Nohta, Tomohiko Mikawa, Eijiro Kojima, Masatoshi YamaguchiAbstract:We developed a fluorous scavenging-derivatization method for reagent peak-free liquid chromatography (LC)-fluorescence analysis of carboxylic acids. In this method, carboxylic acids were fluorescently derivatized with 1-pyrenemEthylamine in the presence of 1-Ethyl-3-(3-dimEthylaminopropyl)carbodiimide and 1-hydroxy-1H-benzotriazole. Residual excess unreacted reagent was tagged with 2-(perfluorooctyl)Ethyl Isocyanate and could be selectively removed by microfluorous solid-phase extraction before LC analysis. With use of this method, eight fluorescent derivatives of linear aliphatic carboxylic acids (C(1)-C(8)) can be separated within 30 min by reversed-phase LC with gradient elution. In the chromatogram obtained, the fluorous-tagged unreacted reagent peak is greatly decreased after microfluorous solid-phase extraction and does not interfere with the quantification of each acid. With use of microfluorous solid-phase extraction with 80% (v/v) aqueous methanol elution, over 99.9% of the unreacted fluorescent reagent was removed. The detection limits (signal-to-noise ratio of 3) for the carboxylic acids examined are 2.3-8.0 fmol per 10-microL injection. We also applied this method successfully to the analysis of highly polar carboxylic acids such as alpha-keto acids and tricarboxylic acid cycle metabolites.
Eduardo C. Meurer - One of the best experts on this subject based on the ideXlab platform.
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Cyclization reactions of acylium and thioacylium ions with Isocyanates and isothiocyanates: Gas phase synthesis of 3,4-dihydro-2,4-dioxo-2H-1,3,5-oxadiazinium ions
Journal of the American Society for Mass Spectrometry, 2005Co-Authors: Eduardo C. Meurer, Regina Sparrapan, Daniela M. Tomazela, Marcos N. Eberlin, Rodinei AugustiAbstract:Gas-phase reactions of several acylium and thioacylium ions, that is H_2C=N-C^+=O, H_2C=N-C^+=S, O=C=N-C^+=O, S=C=N-C^+=O, H_3C-C^+=O, and (CH_3)_2N-C^+=O, with both a model Isocyanate and isothiocyanate, that is, C_2H_5-N=C=O and C_2H_5-N=C=S, were investigated using tandem-in-space pentaquadrupole mass spectrometry. In these reactions, the formation of mono- and double-addition products is observed concurrently with proton transfer products. The double-addition products are far more favored in reactions with Ethyl Isocyanate, whereas the reactions with Ethyl isothiocyanate form, preferentially, either the mono-addition product or proton transfer products, or both. Retro-addition dominates the low-energy collision-induced dissociation of the mono- and double-addition products with reformation of the corresponding reactant ions. Ab initio calculations at Becke3LYP//6-311 + G(d,p) level indicate that cyclization is favored for the double-addition products and that products equivalent to those synthesized in solution, that is, of 3,4-dihydro-2,4-dioxo-2H-1,3,5-oxadiazinium ions and sulfur analogs, are formed.
Regina Sparrapan - One of the best experts on this subject based on the ideXlab platform.
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Cyclization reactions of acylium and thioacylium ions with Isocyanates and isothiocyanates: Gas phase synthesis of 3,4-dihydro-2,4-dioxo-2H-1,3,5-oxadiazinium ions
Journal of the American Society for Mass Spectrometry, 2005Co-Authors: Eduardo C. Meurer, Regina Sparrapan, Daniela M. Tomazela, Marcos N. Eberlin, Rodinei AugustiAbstract:Gas-phase reactions of several acylium and thioacylium ions, that is H_2C=N-C^+=O, H_2C=N-C^+=S, O=C=N-C^+=O, S=C=N-C^+=O, H_3C-C^+=O, and (CH_3)_2N-C^+=O, with both a model Isocyanate and isothiocyanate, that is, C_2H_5-N=C=O and C_2H_5-N=C=S, were investigated using tandem-in-space pentaquadrupole mass spectrometry. In these reactions, the formation of mono- and double-addition products is observed concurrently with proton transfer products. The double-addition products are far more favored in reactions with Ethyl Isocyanate, whereas the reactions with Ethyl isothiocyanate form, preferentially, either the mono-addition product or proton transfer products, or both. Retro-addition dominates the low-energy collision-induced dissociation of the mono- and double-addition products with reformation of the corresponding reactant ions. Ab initio calculations at Becke3LYP//6-311 + G(d,p) level indicate that cyclization is favored for the double-addition products and that products equivalent to those synthesized in solution, that is, of 3,4-dihydro-2,4-dioxo-2H-1,3,5-oxadiazinium ions and sulfur analogs, are formed.