Determination of D- and L-enantiomers of methionine and [2H3]methionine in plasma by gas chromatography-mass spectrometry.
A method for the stereoselective determination of D- and L-enantiomers of both methionine and [(2)H3]methionine in rat plasma was developed using gas chromatography-mass spectrometry with selected-ion monitoring (GC-MS-SIM). DL-[(2)H7]Methionine was used as analytical internal standard to account for losses associated with the extraction, derivatization and chromatography. The amino acids were purified by cation-exchange chromatography using BondElut SCX cartridge and derivatized with HCl in methanol to form methyl ester followed by subsequent N-acylation with optically active (+)-alpha-methoxy-alpha-trifluoromethylphenylacetyl chloride to form diastereomeric amide. Quantification was performed by SIM of the molecular-related ions of the diastereomers on the chemical ionization mode. Endogenous L-methionine concentrations in 50 microl of rat plasma were measured with relative intra- and inter-day precision of 4.0 and 6.3%, respectively. The intra- and inter-day reproducibility in the amounts of D- and L-[(2)H3]methionine determined were in good agreement with actual amount added.
Hasegawa
Hiroshi
H
Department of Pathophysiology, School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan. hasegawa@ps.toyaku.ac.jp
Shinohara
Yoshihiko
Y
Akahane
Kenji
K
Hashimoto
Takao
T
D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007275:Injections, Intravenous; D008297:Male; D008715:Methionine / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D013237:Stereoisomerism; D014316:Tritium
D014316:Tritium; D008715:Methionine