VAPOR GENERATION FOURIER-TRANSFORM INFRARED DIRECT DETERMINATION OF ETHANOL IN ALCOHOLIC BEVERAGES

A procedure is proposed for the direct determination of ethanol in alc oholic beverages. The method is based on the injection of small volume s of untreated samples into a heated Pyrex glass reactor in which, at a temperature between 80 and 100 degrees C, the ethanol is volatilized and introduced by means of a nitrogen carrier flow into a gas cell of an FTIR spectrometer. The measurement of the area of the flow injecti on recording, obtained from the absorbance of the transient signals, i n the wavenumber range between 1150 and 950 cm(-1), allows the direct quantification of ethanol without water background problems and free f rom interferences from sugars, providing a limit of detection of 0.02% v/v and typical RSDs between 0.11 and 0.5% for five analyses of the s ame sample containing between 5 and 30% v/v ethanol. The sampling freq uency of the method is 51 h(-1) and accurate results were obtained for different types of alcoholic beverages, from low-alcohol beers to win es and spirits.