A comparison of the validity of gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry analysis of urine samples II

Abstract

On November 25, 2008, the U.S. Department of Health and Human Services posted a final notice in the Federal Register authorizing the use of liquid chromatography–tandem mass spectrometry (LC–MS–MS) and other technologies in federally regulated workplace drug testing (WPDT) programs. To support this change, it is essential to explicitly demonstrate that LC–MS–MS, as a technology, can produce results at least as valid as gas chromatography (GC)–MS, the long-accepted standard in confirmatory analytical technologies for drugs of abuse. A series of manufactured control urine samples (n = 10 for each analyte) containing amphetamine, methamphetamine, (±)-3,4-methylenedioxyamphetamine, (±)-3,4-methylenedioxymethamphetamine, (±)-3,4-methylenedioxyethylamphetamine, phencyclidine, and (±)-11-nor-9-carboxy-?9-tetrahydrocannabinol at concentrations ranging from 10% to 2000% of federal cutoffs were analyzed with replication by five federally regulated laboratories using GC–MS and at RTI International using LC–MS–MS. Interference samples as described in the National Laboratory Certification Program 2009 Manual were analyzed by GC–MS and LC–MS–MS as well as previously confirmed urine specimens of WPDT origin. Matrix effects were assessed for LC–MS–MS. Results indicated that LC–MS–MS analysis produced results at least as precise, accurate, and specific as GC–MS for the analytes investigated in this study. Matrix effects, while evident, could be controlled by the use of matrix-matched controls and calibrators with deuterated internal standards.