Identification of new metabolites of phosphoramide and nor-nitrogen mustards and cyclophosphamide in rat urine using ion cluster techniques.

The metabolism of nor-nitrogen (NNM) and phosphoramide mustards (PM) and cyclophosphamide (CP) was investigated in the Sprague-Dawley rat using chemical ionization mass spectrometry and ion cluster techniques. Following administrations of a 1:1 mixture of the non-labeled and the corresponding side-chain deuterium-labeled compounds to separate rats, the urinary extracts were screened for cluster ions which were characteristic of the administered compounds and their derived metabolites, and on this basis, tentative identifications of known and new metabolites were accomplished. Combining derivatization, deuterium labeling on strategic locations, gas chromatography/mass spectrometry, and chemical synthesis in some cases, 3-(2-chloroethyl)-1,3-oxazolidin-2-one was identified as a major metabolite for NNM, PM and CP and 3-(2-chloroethyl)-4-hydroxy-1,3-oxazolidin-2-one was identified as a major metabolite for NNM and PM, but a minor metabolite for CP. A new dechlorinated metabolite for CP, 3-(2-hydroxyethyl)-1,3-oxazolidin-2-one, was also identified.