Evaluation of a modified alcohol dehydrogenase assay for the determination of ethanol in blood

We evaluated a new alcohol dehydrogenase (EC 1.1.1.1) enzymic assay (ADH-glycine, Sigma Chemical Co.) for the determination of ethanol in blood. This assay differs from the manufacturer's previous assay (ADH-pyrophosphate) in that glycine replaces pyrophosphate as the buffer and hydrazine replaces semicarbazide as the trapping agent. The standard curve for the assay was linear over blood ethanol concentrations of 0.50-5.00 g/L. The reaction time of the assay was 10 min. At 1.00 g/L within-run and between-run CVs were 3.96% (n = 20) and 4.01% (n = 20), respectively. Mean analytical recovery of ethanol added to whole blood at 0.50-5.00 g/L was 99.7% (SD 2.6%). We performed 100 consecutive clinical and forensic determinations by the ADH-glycine assay, the ADH-pyrophosphate assay, and gas chromatography. Correlation coefficients of the results by least-square linear regression were 0.995 for ADH-pyrophosphate vs ADH-glycine, and 0.990 for gas chromatography vs ADH-glycine. The major advantage of the ADH-glycine assay over the ADH-pyrophosphate assay is the shorter reaction time, 10 min vs 30 min.