title: Determination of glycerol in alcoholic beverages using packed bed reactors with immobilized glycerol dehydrogenase and an amperometric FIA system.
abstract: A flow injection analysis system incorporating amperometric detection and enzyme reactor for glycerol determination in alcoholic beverages is described. The reactor is based on the glycerol dehydrogenase system, and the enzyme was immobilized through chemical modification on several supporting materials such as aminopropyl and isothiocyanate controlled pore glass, aminopolystyrene resin and m-aminobenzyloxymethyl cellulose. NADH, the product of the enzymatic reaction, was monitored amperometrically with a three-electrode wall-jet type flow through cell, at + 0.5 V vs. Ag/AgCl. The method was evaluated in the presence or absence of potassium and the following linear dynamic ranges were found: 2 x 10(-5) -2 x 10(-4) mol l(-1) and 4 x 10(-5) -4 x 10(-4) mol l(-1), respectively. The interference effects of various compounds were also studied. The relative standard deviation was found to be better than 1.0% (n = 6). The reactors are stable for over a period of 3 months and after about 2500 injections. Under optimum working conditions the sampling frequency was 30 samples h(-1). The successive application of the method was confirmed by comparison with a reference method. The mean relative error is 2.2% and the recovery 95-102%.
authors.forename: M I
authors.initials: MI
authors.lastname: Prodromidis
authors.forename: C D
authors.initials: CD
authors.lastname: Stalikas
authors.forename: S M
authors.initials: SM
authors.lastname: Tzouwara-Karayanni
authors.forename: M I
authors.initials: MI
authors.lastname: Karayannis