Comparison and Evaluation of DRI® Methamphetamine, DRI Ecstasy, Abuscreen® ONLINE Amphetamine, and a Modified Abuscreen ONLINE Amphetamine Screening Immunoassays for the Detection of Amphetamine (AMP), Methamphetamine (MTH), 3,4-Methylenedioxyamphetamine (MDA) and 3,4-Methylenedioxymethamphetamine (MDMA) in Human Urine*

Four immunoassays for detecting amphetamine, methamphetamine, MDA, and MDMA were tested on about 27,500 human urine samples and 7,000 control samples over eight days. The DRI ecstasy reagent detected about 23% more MDMA-positive samples than the ONLINE reagent and had a confirmation rate near 90%. The modified ONLINE reagent, which included sodium periodate and was calibrated with MDMA, performed poorly, with control failure rates up to 38.3% and no improved MDMA sensitivity. The DRI methamphetamine reagent had a low confirmation rate (6% or less) and frequently gave positive results for samples containing only ephedrine or pseudoephedrine.

Study at a glance

Abstract

The performances of four immunoassays (DRI amphetamines, DRI ecstasy, Abuscreen ONLINE amphetamines, and a modified Abuscreen ONLINE amphetamines) were evaluated for control failure rates, sensitivity, and specificity for amphetamine (AMP), methamphetamine (MTH), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxymethamphetamine (MDMA). The two DRI reagents and the ONLINE reagents were run according to manufacturer specifications using a Roche Hitachi Modular DDP system. The modified ONLINE reagent was calibrated with MDMA and had 16mM sodium periodate added to the R2 reagent. These assays were run on approximately 27,500 human urine samples and 7000 control urine samples prepared at 350 and 674 ng/mL over the course of 8 days. All assays were calibrated using a single point, qualitative cutoff standard with the manufacturer-recommended compound at the Department of Defense cutoff (500 ng/mL). Gas chromatography-mass spectrometry (GC-MS) confirmation was conducted on screened-positive samples. Control performance for the manufacturer recommended assays was excellent, with a maximum qualitative control failure rate of 2.03%. The modified ONLINE reagent demonstrated poor control performance with a maximum failure rate of 38.3% and showed no improved MDMA sensitivity when compared with the ONLINE reagent; the confirmation rate (20%) was improved when compared with the production ONLINE reagent (8%). The DRI ecstasy reagent provided improved sensitivity for MDMA as compared with the ONLINE reagent, with approximately 23% more samples screening and confirming positive for MDMA and a confirmation rate of approximately 90%. The DRI methamphetamine reagent had a low confirmation rate (6% or less) and produced numerous positives for samples with only ephedrine or pseudoephedrine present.