title: Monitoring the behaviour of 4-ketocyclophosphamide versus cyclophosphamide during capillary gas chromatography by mass spectrometry.
abstract: Capillary Gas Chromatography (CGC) is capable of determining underivatized cyclophosphamide (CPA) using SCOT OV 275 columns. Then CPA is subjected to in situ degradation resulting in formation of a cyclization product which can be determined selectively in biological fluids. In routine bioanalysis however cyclization products of CPA metabolites might interfere, e.g. 4-keto CPA. In the present study possible formation of cyclization products of 4-keto CPA similar to CPA was monitored by Mass Spectrometry. Cyclization of 4-keto CPA in situ was demonstrated to occur, resulting in a product similar to that of CPA. Both cyclization products could be determined selectively and it appeared that in situ cyclization of 4-keto CPA was negligible (less than 5%), probably owing to extra stabilization of the CPA metabolite by keto-enol tautomerism as has been demonstrated by NMR.
mesh_terms: D003520:Cyclophosphamide / Q000031:analogs & derivatives* / Q000032:analysis* / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007202:Indicators and Reagents
chemical_list: D007202:Indicators and Reagents; D003520:Cyclophosphamide; C008226:4-ketocyclophosphamide