Simultaneous quantification of 19 drugs/metabolites in urine important for pain management by liquid chromatography-tandem mass spectrometry

Abstract

Monitoring pain management drugs and frequently abused drugs is important for physicians to assess patient compliance. Liquid chromatography-tandem mass spectrometry offers high specificity needed for this purpose. In this report, a novel liquid chromatography-tandem mass spectrometry method for simultaneously monitoring 19 drugs/metabolites in urine was developed and validated. Sample preparation included hydrolysis, dilution and turbulent flow online extraction. Analysis was achieved by reverse phase liquid chromatography and triple-quadruple tandem mass spectrometry. Two fragment ions, one for quantification and the other for assuring identification, were monitored for each analyte. No matrix effect or interference was observed. Lower limits of quantification ranged from 5 to 25 ng/mL. Within the linear range, analytical recovery was between 85.8% and 119.4%. Intra-assay and total coefficient of variations were between 0.2% and 12.7%. This method was compared with mass spectrometry methods offered by two other laboratories using 82 patient samples and 60 spiked urine samples showing 60%-100% agreement. The current method identified more positive samples for all analytes except THCA. The discrepancy in detection rates was primarily due to the different cut-offs used by the other laboratories. A sensitive and specific liquid chromatography-tandem mass spectrometry method was developed for measuring 19 drugs/metabolites in urine important for pain management clinics.