Determination of ifosfamide by gas chromatography-mass spectrometry

Ifosfamtde, an oxazaphosphonne, IS thermally stable dunng elutton m gas chromatography (GC) at temperatures above 2OO”C, m contrast to tts structural Isomer cyclophosphamrde. Both 2.65~gm and 0.32~pm OV-1 columns were effrctent for GC of tfosfamtde wrthout derivatmation. Mass spectrometry (MS), showed that Intact tfosfamrde was eluted without interference from naturally occurring metabohtes in blood plasma. Ifosfarmde can be momtored, by captllary GC-MS wtthout derivatuatton, m blood plasma from cancer patients treated wtth the drug. Only a hqmd-hqutd extraction is required before inJectron of the sample. A smgIe peak of tfosfamtde is detected wtth molecular mass 260, fragmentation starts wtth loss of CH,Cl ([M CH,Cl], m/r 211). The hmrt of determmatron for tfosfamtde m human plasma was about 50 nM (10 ng ml-‘). Recovery, quality of cahbration curves and reproductbdtty were suitable for the rapid determinatton of ifosfamide in the range 0.01-1000 gg ml-’