DIRECT GAS-CHROMATOGRAPHIC DETERMINATION OF DECHLOROETHYLCYCLOPHOSPHAMIDE FOLLOWING MICROSOMAL INCUBATION OF CYCLOPHOSPHAMIDE

A method for the sensitive determination of dechloroethylcyclophospham ide (3-DCl) in microsomal incubation mixtures was developed. 3-DCl, a side-chain oxidation product of cyclophosphamide (CP), was isolated by extraction with acetic acid ethyl ester following solid-phase extract ion on C-8 cartridges. Quantification of the metabolite was performed by direct capillary gas chromatography with a nitrogen-phosphorus dete ctor without prior derivatization. The method showed good sensitivity and reproducibility with a detection limit of 1 ng/ml and a limit of q uantification of 5 ng/ml. The suitability of the method is shown for t he quantification of 3-DCl following incubation of CP with human liver microsomes.