ENZYMATIC DETERMINATION OF ALCOHOL MIXTURES AT THE NANOGRAM LEVEL BY THE STOPPED-FLOW TECHNIQUE

A sensitive kinetic enzymatic method for the individual and joint determination of lower straight-chain alcohols is reported. The method is based on reaction of the alcohols with the alcohol dehydrogenase-nicotinamide adenine dinucleotide system, which is monitored by measuring the initial rate of change of the absorbance or fluorescence intensity of the reduced coenzyme formed by using the stopped-flow technique. Methanol, ethanol, propanol and butanol can thus be determined over the range 3.0 X 10(-8)-1.0 X 10(-6) M with a relative standard deviation of ca. 1.2-3.8%. Spectrofluorimetric measurements are better suited to the individual determinations, whereas spectrophotometric measurements are more useful for resolving alcohol mixtures using the Kalman filter algorithm. Mixtures of methanol-butanol, ethanol-butanol and methanol-propanol at the submicromolar level were successfully resolved with errors of less than 10%.