title: Simultaneous determination of methionine and total homocysteine in human plasma by gas chromatography-mass spectrometry.
abstract: A gas chromatographic-mass spectrometric method for the simultaneous determination of methionine and total homocysteine in human plasma is described. DL-[2H4]Methionine and DL-[2H8]homocystine were used as internal standards. The method involved reduction of the disulfide bond with dithiothreitol, purification by cation-exchange chromatography using a BondElut SCX cartridge and derivatization with isobutyl chlorocarbonate in water-ethanol-pyridine. Quantitation was performed by selected-ion monitoring of the quasi-molecular ions of N(O,S)-isobutyloxycarbonyl ethyl ester (IBC-OEt) derivatives for methionine and [2H4]methionine, respectively, and the fragment ions ([M+H-COOisoBu-COOEt]+) for TBC-OEt derivatives for homocysteine and [2H4]homocysteine, respectively. The sensitivity, specificity, accuracy and precision of the method were demonstrated to be satisfactory for measuring concentrations of methionine and total homocysteine in human plasma.
authors.affiliation: School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan. sinohara@ps.toyaku.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Shinohara
authors.forename: H
authors.initials: H
authors.lastname: Hasegawa
authors.forename: K
authors.initials: K
authors.lastname: Tagoku
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
mesh_terms: D000328:Adult; D002138:Calibration; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D008715:Methionine / Q000097:blood*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006710:Homocysteine; D008715:Methionine