Studies on the disposition of cyclophosphamide (NSC-26271) in tumor-bearing mice by means of gas chromatography-chemical ionization-mass fragmentography.

The disposition of cyclophosphamide (CP) in mice bearing Lewis lung tumor has been studied by chemical ionization-mass fragmentography using isophosphamide as the internal standard. The drugs were analyzed as their N-trifluoroacetyl derivatives in order to increase sensitivity and to avoid column adsorption and decomposition phenomena. The minimum detectable amount was 500 pg/injection. Linearity was found up to microgram amounts of the substance without any interference of endogenous compounds.