title: Drug screening with EMIT reagents: a quantitative approach to quality control.
abstract: We investigated the precision, linearity, accuracy, and stability of quantitative results for five drugs of abuse [amphetamines, benzoylecgonine, opiates, phencyclidine, and the cannabinoid-tetrahydrocannabinol (THC)-9-acid metabolite], analyzed in control specimens by using EMIT d.a.u. reagents (Syva Co.) with a Monarch 2000 analyzer with a nonlinear interpolation curve-fitting algorithm. The within-day and between-days coefficients of variation (CVs) were less than 5% for all drugs except THC-9-acid, which had a CV between 10% and 20%. The drift of control values during a 30-day stability study was less than 10% from target values for three weeks after a single calibration, except for THC-9-acid control values, which were stable for only two to three days. Daily calibration reduced the drift away from target values during the 30-day stability study and produced optimum precision of all drug assays. Mean control values near the National Institute on Drug Abuse cutoff limits were within 10% of their target values.
authors.affiliation: Department of Pathology, University of New Mexico School of Medicine, Albuquerque 87131.
authors.forename: J C
authors.initials: JC
authors.lastname: Standefer
authors.forename: R C
authors.initials: RC
authors.lastname: Backer
mesh_terms: D000928:Antidepressive Agents / Q000652:urine; D002186:Cannabinoids / Q000652:urine; D003565:Cytidine Diphosphate; D006801:Humans; D007124:Immunoenzyme Techniques; D008694:Methamphetamine / Q000652:urine; D009294:Narcotics / Q000652:urine; D010622:Phencyclidine / Q000652:urine; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling; D015813:Substance Abuse Detection / Q000592:standards*
chemical_list: D000928:Antidepressive Agents; D002186:Cannabinoids; D009294:Narcotics; D008694:Methamphetamine; D003565:Cytidine Diphosphate; D010622:Phencyclidine