Studies on Drug Metabolism by Use of Isotopes XX: Ion Cluster Technique for Detection of Urinary Metabolites of 1-Butyryl-4-cinnamylpiperazine by Mass Chromatography

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An ion cluster technique and mass chromatography were used for the structural elucidation of several unidentified urinary metabolites of l-butyryl-4-cinnamylpiperazine (I) in mice and guinea pigs. The urinary metabolites in guinea pigs and mice receiving a single 100mg/kg dose of an equimolar mixture of l-butyryl-4-[aromatic-d5]-cin- namylpiperazine (I-d5) hydrochloride and I hydrochloride (I.I-d5) were purified and subjected to trimethylsilyl derivatization with bis(tri-methylsilybacetamide, followed by GLC-mass spectrometry-computer analysis. Appropriate fragment and molecular ions of unidentified metabolites were selected based on the major mass fragment ions appearing in the mass spectra of the previously identified metabolites of I to provide the mass chromatograms. The presence of ion clusters as doublet peaks in the mass chromatograms indicated that the corresponding total ion peaks originated from the administered I:I-d5. The mass spectra of selected scans from the total ion chromatogram were plotted, and the structures of unidentified metabolites were readily determined by the presence of ion clusters separated by 3–5 mass units and by the shift of the fragment ions. By using this technique, six previously unidentified metabolites were identified in the urine of guinea pigs and two were identified in the urine of mice.