Detection of 41 Drugs and Metabolites in Urine with Internal Hydrolysis Control by Liquid Chromatography-Tandem Mass Spectrometry.

Regular monitoring of pain management and substance use disorder patients through urine drug screening is important for assessing patient compliance with prescribed drugs and abstinence from non-prescribed drugs. Sample analysis is commonly performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) as multiple drugs and metabolites can be monitored from one sample. However, challenges faced in developing an LC-MS/MS method for multiple analytes in urine include variability in matrix and concentration from sample to sample and variable chemistry of many pain management drugs and associated metabolites affecting accuracy and precision of results. We describe here an LC-MS/MS method for analysis of 41 drugs and metabolites commonly prescribed for pain management patients. The developed method uses enzymatic hydrolysis followed by cation exchange solid phase extraction. Resorufin-glucuronide is used as an internal hydrolysis control to monitor hydrolysis in each patient sample and minimize false negatives. Analysis was performed using an Agilent 6470 mass spectrometer in dynamic multiple reaction monitoring mode.