ENZYMATIC DETERMINATION OF ETHANOL BASED ON THE INTRINSIC FLUORESCENCE OF ALCOHOL-DEHYDROGENASE

A fluorimetric enzymatic method for the determination of ethanol is pr esented. The method is based on the intrinsic fluorescence changes cau sed in alcohol dehydrogenase (ADH) during the enzymatic reaction. This Variation is due to the different inner filter effects of the co-enzy me (NAD(+)) and its reduced form (NADH). The latter is generated durin g the enzymatic reaction. A study is made of the origin of the ADH flu orescence signal using a mathematical model, which makes it possible t o explain the linear response between the enzyme's analytical signal a nd the concentration of ethanol ranging from 5.5 x 10(-5) to 3.2 x 10( -3) M. The 3 sigma limit of detection is 3.1 x 10(-6) M, and the relat ive standard deviation for 6 determinations at 1.0 x 10(-4) M ethanol is 2.8%. The method is applied to low ethanol concentration drink samp les and vinegar without pre-treatment.