ANALYSIS OF IFOSFAMIDE, 4-HYDROXYIFOSFAMIDE, N2-DECHLOROETHYLIFOSFAMIDE, N3-DECHLOROETHYLIFOSFAMIDE AND IPHOSPHORAMIDE MUSTARD IN PLASMA BYGAS-CHROMATOGRAPHY MASS-SPECTROMETRY

A sensitive and specific method for the simultaneous quantitation of i fosfamide (IF), 4-hydroxylifosfamide (4-OHIF), N2-dechloroethylifosfam ide (N2D), N3-dechloroethylifosfamide (N3D) and iphosphoramide mustard (IPM) has been developed using gas chromatography-mass spectrometry ( GC-MS) with an ion-trap mass spectrometer. Deuterium labeled analogues for each of these analytes were synthesized as the internal standards . The labile 4-OHIF in plasma was first converted to the more stable c yanohydrin adducts before dichloromethane extraction. IPM was extracte d by C-18 reversed-phase resin. All analytes were converted to their s ilyl derivatives before GC-MS analysis. The sensitivity limits ranged from 0.1 to 0.5 mu g/ml when 100 mu l of plasma was used. This method was validated with within-run coefficients of variation less than 5% ( n=8) and between-run coefficients of variation less than 12% (n=6). Th e method was applied to the determination of plasma levels of LF and m etabolites in the rat.