Biochemistry and Biotechnology
Wiley InterScience Backfile Collection 1832-2000
Process Engineering, Biotechnology, Nutrition Technology
We have examined the utility of a commercial kit procedure for the determination of ethanol (EtOH), based upon its enzymatic oxidation and the concurrent production of NADH, monitored by photometry at 340 nm. We found that the equilibrium production of NADH is not stoichiometric with respect to initial ethanol concentration, and that with this procedure, the calibration curve for end-point assay of ethanol is linear only for very dilute solutions. Likewise, the kinetic assay of ethanol using the kit procedure is limited to very dilute samples (i.e., concentration in the reaction mixture of ≤2.3 mg EtOH/liter). We describe a simple modification of the kit procedure which makes it amenable to the precise kinetic assay of up to 150 mg EtOH/liter in the reaction mixture. This increase in the dynamic range for kinetic assay of ethanol results form the use of hydrazine both as a trapping agent for the acetaldehyde reaction product and as a competitive inhibitor of alcohol dehydrogenase enzyme.
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