Simultaneous analysis of analgesics and their major metabolites by liquid chromatography-electrospray ion trap mass spectrometry

Abstract

A high-throughput analysis method applying liquid chromatography-electrospray ionization-ion trap mass spectrometry (LC-ESI-ITMS) for the simultaneous analysis of analgesics and their in vitro metabolites is described. Four analgesics, including tramadol, ketamine, pethidine and methadone, were individually incubated with rat liver microsome S₉ fraction initially. The incubation samples were pooled together for analysis by LC-ESI-ITMS in positive ion and full-scan detection modes. The analgesics and their metabolites were identified from the detection of the protonated molecules. The metabolite detection was confirmed by tandem mass spectrometry (MSⁿ) analysis. In addition, the metabolic stabilities of the analgesics were determined by comparing the peak intensities between the control and incubated samples. The obtained results indicated that the method could provide a significant increase in analytical throughput and can be applied in the detection of samples in forensic analysis and in clinically addicted cases.