Validation of the Cozart® Amphetamine Microplate EIA for the analysis of amphetamines in oral fluid

The purpose of this study was to determine the performance characteristics of the Cozart® Amphetamine Microplate EIA for detecting amphetamine in oral fluid. Oral fluid samples were collected using the Cozart® RapiScan Collection System from 135 volunteer donors from drug treatment clinics. A further 35 oral fluid samples were collected from volunteer donors who were not drug users. The samples were analyzed in the laboratory using the Cozart® Amphetamine Microplate EIA and confirmed using gas chromatography–mass spectrometry (GC–MS). The samples were stored frozen until analysis by GC–MS. The intra-assay precision for the Cozart® Amphetamine Microplate EIA for amphetamine in oral fluid over forty assays was 2.74–7.1% CV (within assay) and 3.4–7.0% CV (within day). A total of 78 samples were positive for various amphetamines and related designer drugs. The Cozart® Amphetamine Microplate EIA, using a cutoff of 45 ng/ml amphetamine equivalents in neat oral fluid, had a sensitivity of 91.7 ± 3.3% and a specificity of 95.9 ± 1.9% versus GC–MS using a cutoff of 30 ng/ml. A series of potential adulterants of oral fluid were evaluated and shown not to alter the outcome of the test result.