Background: 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.
Methods: 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.
Results: 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.
Conclusions: A sensitive and specific liquid chromatography-tandem mass spectrometry method was developed for measuring 19 drugs/metabolites in urine important for pain management clinics.