Correct quantitative determination of ethanol and volatile compounds in alcohol products
Determination of the volume content of ethanol in the alcohol products in practice is usually determined by pycnometry, electronic densimetry, or densimetry using a hydrostatic balance in accordance with Commission Regulation No 2870/2000. However, these methods determine directly only density of the tested liquid sample and does not take into account the effects of other volatile components such as aldehydes, esters and higher alcohols. So they are appropriate only for binary water-ethanol solutions in accordance with international table adopted by the International Legal Metrology Organization in its Recommendation No 22. Availability notable concentrations of the higher alcohols and ethers in different alcohol-based products, e. g. in whisky, cognac, brandy, wine as well as in waste alcohol and alcohol beverage production, leads to the significant contribution of these compounds in the value of the density of tested alcohol-containing sample. As a result, determination of the volume of ethanol content for such alcohol products in gives the value of the strength, which may significantly differ from the true one. Using incorrectly calculated volume content of ethyl alcohol leads to incorrect results determining the quantities of volatile compounds in the alcohol-containing products, expressed in milligrams per liter of absolute alcohol. We propose experimental results of the method of correct determination of ethanol and other volatile compounds content in waste products of alcohol and alcoholic beverage industry by gas chromatography. Calculations are based on the measured value of sample density and volatile compound concentrations expressed in mg per liter of absolute alcohol [JAFC 61(2013)2950]. The method can be easily incorporated into daily practice of analytical and control laboratories with no additional material, financial or time costs.