Kinetics of hydrolysis in vitro of nornitrogen mustard,a metabolite of phosphoramide mustard and cyclophosphamide

A gas chromatographic (GC-ECD) method was developed for the determination of nornitrogen mustard (NOR) and its hydrolysis products. The method was based on derivatization by heptafluorobutyric anhydride. The structures of the derivatives of NOR were established by GC-MS. The method was used to characterize the rate of transformation of NOR and phosphoramide mustard (PAM), important metabolites of cyclophosphamide, into secondary products in vitro at 37° C and pH 7.4. The rate of disappearance of NOR had a half-life of 20 min. The half-life of appearance of N-(2-chloroethyl)-N-(2-hydroxy-ethyl)amine (NOR-OH) was 19 min. While most NOR appeared to be converted to NOR-OH, the yield of N,N-bis(2-hydroxyethyl)amine (NOR-OH-OH) was a small fraction of the starting material. The disappearance of NOR, when PAM was used as a starting material, had a half-life of 19 min; in these experiments NOR-OH and NOR-OH-OH were relatively much more abundant compared to when NOR was used as the starting material.Abbreviations NOR nornitrogen mustard - NOR-OH N-(2-chloroethyl)-N-(2-hydroxyethyl)amine - NOR-OH-OH, N N-bisN,-(2-hydroxyethyl)amine - PAM phosphoramide mustard - GC gaschromatography - GC-ECD gas chromatography-electron capture detection - GC-MS gas chromatography-mass spectroscopy - HFBA heptafluorobutyric anhydride