Automated enzymic determination of ethanol in blood, serum, and urine with a miniature centrifugal analyzer.

We describe an automated spectrophotometric reaction-rate method for determination of ethanol in serum and urine with a miniature centrifugal analyzer. The theanol is selectively oxidized in the presence of alcochol dehydrogenase and NAD+ to form NADH, which is measured by the rate of change of its absorbance. Reaction rates are determined automatically, and unknown concentrations are calculated from a computer-generated working curve based on aqueous ethanol standards. Blood, serum, or urine specimens need not be deproteinized. The method permits duplicate analysis of at least 30 samples per hour. Coefficients of variation and relative errors are about 2-3% for ethanol concentrations of 0.3-3.0 mug per 2 mul of sample. Analytical recovery of ethanol added to serum is 92-103% (average, 98.5%). Comparisons with distillation-oxidation, gas-chromatographic, and conventional enzymic procedures give satisfactory agreement.