Gas chromatographic-mass spectrometric determination of alpha-ketoisocaproic acid and [H-2(7)]alpha-ketoisocaproic acid in plasma after derivatization with N-phenyl-1,2-phenylenediamine

Citation
T. Matsukawa et al., Gas chromatographic-mass spectrometric determination of alpha-ketoisocaproic acid and [H-2(7)]alpha-ketoisocaproic acid in plasma after derivatization with N-phenyl-1,2-phenylenediamine, J CHROMAT B, 751(2), 2001, pp. 213-220
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry & Analysis
Journal title
JOURNAL OF CHROMATOGRAPHY B
ISSN journal
1387-2273 → ACNP
Volume
751
Issue
2
Year of publication
2001
Pages
213 - 220
Database
ISI
SICI code
1387-2273(20010225)751:2<213:GCSDOA>2.0.ZU;2-U
Abstract
A method for determination of alpha -ketoisocaproic acid (KIC) and [4,5,5,5 ,6,6,6-H-2(7)]alpha -ketoisocaproic acid ([H-2(7)]KIC) in rat plasma was de veloped using gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM). [5,5,5 H-2(3)]alpha -Ketoisocaproic acid ([H-2(3)]KIC) was use d as an analytical internal standard to account for losses associated with the extraction, derivatization and chromatography. The keto acids were extr acted by cation-exchange chromatography using BondElut SCX cartridge and de rivatized with N-phenyl-1,2-phenylenediamine to form N-phenylquinoxalinone derivatives. Quantitation was performed by SIM of the respective molecular ions at m/z 278, 281 and 285 for the derivatives of KIC, [H-2(3)]KIC and [H -2(7)]KIC on the electron impact method. The limit of detection was found t o be 70 fmol per injection (S/N=3) and the limit of quantitation for [H-2(7 )]KIC was around 50 nM in rat plasma. Endogenous KIC concentrations in 50 m ul of rat plasma were measured with relative intra- and inter-day precision of 4.0% and 3.3%, respectively. The intra- and inter-day precision for [H- 2(7)][KIC spiked to rat plasma in the range of 0.1 to 10 muM gave good repr oducibility with relative standard deviation (RSD) of 6.5% and 5.4%, respec tively. The intra- and inter-day relative errors (RE) for [H-2(7)]KIC were less than 6.4% and 3.8%, respectively. The method was applied to determine the plasma concentration of [H-2(7)]KIC after an intravenous administration of [H-2(7)]KIC in rat. (C) 2001 Elsevier Science B.V. All rights reserved.