CHARACTERIZATION OF POLAR URINARY METABOLITES BY IONSPRAY TANDEM MASS-SPECTROMETRY FOLLOWING DANSYLATION

The present report illustrates the application of dansyl chloride coup led with ion spray tandem mass spectrometry (IS-MS/MS) in identifying polar urinary metabolites. In the course of the metabolism studies of a drug that is currently in development, the urine from rats and dogs was collected following oral administration of radiolabelled compound. Urinary metabolic profiles of the rat and dog indicated the presence of four major peaks and one major peak, respectively, in the radiochro matogram. Since all attempts to identify the peaks by conventional MS/ MS techniques failed, the metabolites were isolated by fraction collec tion and dansylated, Derivatization of the metabolites resulted in the formation of more hydrophobic, readily ionizable species which were m ore sensitive in IS-MS/MS analysis than the underivatized metabolites. Examination of the molecular ions and the product ion mass spectra of these derivatives revealed the structures of all the urinary metaboli tes. The metabolites in the rat and the dog were 4-hydroxyphenylpipera zine glucuronide (M1), 1,4-dihydroxyphenyl glucuronide (M2), 1,4-dihyd roxyphenyl sulfate (M3) and phenylpiperazine (M4), Thus, derivatizatio n with dansyl chloride in conjunction with tandem mass spectrometry is a useful tool in identifying polar urinary metabolites. (C) 1998 John Wiley & Sons, Ltd.