GC-MS analysis of ifosfamide

Ifosfamide (IF) is not subjected to thermal degradation during capillary GC, in contrast to its structural isomer cyclophosphamide (CY). Both 2.65 pm and 0.32 /1m OV-l columns proved to be useful in gas chromatographic analysis of IF without any derivatization. Mass spectrometry data demonstrated that intact IF was eluted while no hindrance of naturally occuring metabolites such as 2-dechloroethyl-IF, 3-dechloroethyl-IF, 4-keto-lF and iso-phosphoramide mustard was found. Therefore, IF can be monitored in biological fluids of cancer patients treated with the oxazaphosphorlne by capillary GC-MS without derivatizatlon. A simple liquid-liquid extraction is required prior to introduction of IF into GC. A single peak of IF is detected with molecular mass 260; fragmentation starts with loss of CH2CI: m/z 211 = IF-CH2CI. The limit of determination of IF in human biological nuids was approximately 10 ng ml-t (50 nM). Recovery, quality of calibration curves, reproducibility, withinrun and within-assay precision allowed rapid determination of IF in a range of 0.01-1000 mug ml-1. Data of GC-MS analysis proved that unchanged IF can be determined in plasma and urine extracts without in situ formation of degradation products, during capillary GC.