EBROTIDINE AND ITS METABOLITES STUDIED BY MASS-SPECTROMETRY WITH ELECTROSPRAY-IONIZATION - COMPARISON OF TANDEM AND IN-SOURCE FRAGMENTATION

Electrospray ionization was used for the analysis of ebrotidine and it s potential metabolites. Since standard electrospray gave only the qua si-molecular ions for most of the compounds, two collision induced dis sociation (CID) experiments were carried out in order to obtain struct ural Information: tandem mass spectrometry (MS/MS) and in-source fragm entation by increasing the cone voltage (CVF, cone voltage fragmentati on). CVF produced more fragmentation than MS/MS, and the intensities o f the fragments formed were also greater, Unlike MS/MS spectra, CVF sp ectra gave ions which showed retention of the bromine isotope pattern, adducts with acetate and dehydration, The general fragmentation pathw ays observed for ebrotidine: and its derivatives were basically the sa me for the CVF and MS/MS experiments, Most of the fragments were forme d by the breaking of bonds to heteroatomics. In order to analyse biolo gical samples containing ebrotidine and its biotransformation products , an HPLC/MS separation procedure with simultaneous UV detection was d eveloped, allowing the identification of ebrotidine and its metabolite s in human urine.