GAS CHROMATOGRAPHIC DETERMINATION OF ETHANOL IN SOFT DRINKS USING VAPOR-PHASE DROP MICROEXTRACTION

A simple express procedure for gas chromatographic determination of ethanol in soft drinks is proposed (kwas, grape juice, non-alcoholic beer), based on headspace microextraction of the analyte into a drop (1 μL) of distilled water located above the surface of the analyzed liquid on the tip of the needle of a standard microsyringe for gas chromatography. The detection limit of ethanol is (3–6) × 10 vol. %, the parallel determination time, including headspace extraction, does not exceed 5 min. Propanol-2, which is not detected in beverages, is used as an internal standard. The correctness of the procedure is confirmed by the added–found method, the relative standard deviation does not exceed 7 % at an ethanol concentration in the sample of 10 vol. %.