An evaluation of EMIT-dau Benzodiazepine Metabolite Assay for urine drug screening.

Six hundred postmortem and emergency room urine analysis for benzodiazepines were performed by both the "EMIT-dau Benzodiazepine Metabolite Assay" (EMIT) and thin layer chromatography (TLC). Benzodiazepine drugs or metabolites were detected in 90 urines by TLC and 84 urines by EMIT. Of th six apparent false negative EMIT analysis, three were due to high edogeneous lysozyme activity and three were due to the greater sensitivity of TLC (0.1 mg/L) versus EMIT (0.5 mg/L). The EMIT assay sensitivity for four benzodiazepine drugs and five of their major uninary metabolites was determined. Benzodiazepines unsubstituted at the N-1 position displayed the greatest sensitivity by EMIT assay, 0.5 mg/L. Twenty-six "nonbenzodiazepine" drugs or drug metabolites commonly encountered in urine drug screening, failed to produce significant false positive or false negative results with the EMIT benzodiazepine assay.