High-Throughput Comprehensive Quantitative LC-MS/MS Analysis of Common Drugs and Metabolites (62 Compounds) in Human Urine.

In recent years a multitude of LC-MS/MS assays have been widely reported in commercial and clinical literature demonstrating the simultaneous analyses of dozens of drugs of abuse in human samples. The utility of such assays is meant to supplant the indirect detection based on the classical spectral library approach. Direct and simultaneous analysis via LC-MS/MS technology is made possible by fast acquisition rates in multiple reaction monitoring, as well as sensitivity and high selectivity of the technology for each individual analyte in a complex mixture. Hence, unlike immunoassays, which are not well-suited for the analyses of mixtures, and which may also be prone to false positives from potential interferences, quantitative LC-MS/MS analyses are feasible for complex patient mixtures of drugs of abuse. We hereby present a robust clinical LC-MS/MS assay for the simultaneous and semi-quantitative analysis of up to 62 drugs of abuse in human urine, representing major classes that include opiates, benzodiazepines, amphetamines, etc. The assay utilizes dilute and shoot, whereby the sample is diluted ten times in internal standard reagent and thereafter submitted to the LC-MS instrument, i.e., reversed-phase liquid chromatography coupled to the electrospray ionization multiple reaction monitoring analysis, via the TSQ Endura triple-quadrupole instrument. The assay employs stable isotope-labeled internal standards with a linear response in the 30-300 ng/mL range, effectively semi-quantitative, since this analytical range is well within typical immunoassay cutoffs for most drugs.