Determination of ethanol in beer by flow injection dual-pulse staircase voltammetric detection

Abstract

Dual-pulse staircase voltammetry (DPSV), was studied for the determination of ethanol in beer using electrochemical detection and flow injection (FI). As the method did not require deaeration and had a sufficiently wide linear range to cover the area of application, it could be used for the direct determination of alcohol without any prior separation. Under the optimized conditions, in a 0.10 mol l–1 NaOH solution, the repeatability (relative standard deviation 1.9%, mean = 0.03 mol l–1 and n= 8), linear range (0.01–10 mol l–1) and detection limit (0.0006 mol l–1, 3s of the background current) of the developed method were found to be satisfactory for the determination of ethanol in beer samples by FI with a flow rate of 0.5 ml min–1, an injection volume of 100 µl and a maximum sample throughput of 60 samples per hour, prior to the overlapping of the FI peaks. No interfering effect was observed for additives at the concentrations commonly encountered in beer samples and the method was found to give similar results to the reference AOAC method. The method developed provides a general method for the electrochemical detection of alcohols and other organic compounds with alcoholic hydroxyl groups.