Simultaneous Determination of Multiple Drugs of Abuse and Relevant Metabolites in Urine by LC-MS-MS

A method was developed for the quantitative analysis of 30 drugs of abuse and their metabolites in urine, including opiates, barbiturates, amphetamines, cocaine, cannabinoids, phencyclidine, methadone, and benzodiazepines. This method uses solid-phase extraction (SPE) on an Oasis HLB column followed by liquid chromatography-tandem mass spectrometry. Analytes were quantified by multiple reaction monitoring with the deuterated analogues as internal standards, using an atmospheric pressure ionization-electrospray interface. The method was validated by examining specificity, precision, accuracy, linearity, recovery, reproducibility, and detection limits. The limits of detection ranged from 9 pg/mL to 2.29 ng/mL in urine depending on the analyte. The SPE procedure was automated on a RapidTrace workstation to increase analytical throughput, and the results obtained via automated SPE were compared to those obtained by manual SPE to examine carryover effect, precision, accuracy, recovery, and reproducibility. To evaluate method performance, 108 urine samples were collected anonymously and tested for the presence of these drugs.