A way of direct determination of volatile compounds in spirit drinks by gas chromatography is proposed by using ethanol as internal standard in gas chromatographic analysis of volatile compounds in spirit drinks for routine tests. This method provides determination of volatile compound concentrations in spirit drinks expressed directly in milligrams per liter of absolute alcohol without measuring the alcohol content of the analyzed sample. Theoretical background of the method shows the opportunity to use it in any tested laboratories all over the world and to ascertain in its efficiency and simplicity. The method was approved in control laboratories of Wine and Distillery Plant "Chashniki" (Belarus) and Branch of Joint Stock Company "Rosspirtprom" Wine and Distillery Plant "Cheboksary" (Russia). The experimental results of method validation in the Laboratory of Analytical Research from Research Institute for Nuclear Problems of Belarusian State University are presented.

An extensive study concerning the problem of volatile compounds determination in alcoholic products by gas chromatography has been undertaken in the paper. A row of gravimetrically prepared standard solutions was analysed with three analytical methods: traditional method of internal standard, advanced method of internal standard and external standard method. The main analytical characteristics and metrological parameters of the "Ethanol as Internal Standard" method were compared with the traditional approaches. It was shown that this method leads to correct values of volatiles concentrations and the corresponding metrological characteristics are generally better.

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Background: The quality and safety control of an alcoholic drink is mainly the establishment of its chemical content, particularly the quantity of volatile compounds. Objective: A single-laboratory validation of a gas chromatographic method of direct determination of volatile compounds in spirit drinks was conducted. The discussed method applies ethanol, the major volatile component of an alcoholic beverage, as an internal standard. Possible algorithms of method validation based on interlaboratory study were proposed and described. Methods: Seven standard solutions of the following volatile compounds were prepared gravimetrically in 40% (v/v) water–ethanol solution: acetaldehyde, methyl acetate,ethyl acetate, methanol, 2-propanol, 1-propanol, isobutanol, 1-butanol, and isoamylol. Each sample wasmeasured with the proposed method 30 times in repeatability conditions. Results: Flame ionization detector response was linearly correlated with assigned concentrations at a range of 2 to5000 mg/L of absolute alcohol (AA) with coefficients of determination (R2)more than 0.995 for all analyzed components. Repeatability (RSDr ≤ 4.5%; RSDr ≤ 2.0%), reproducibility (RSDR ≤ 5.0%; RSDR ≤ 2.0%), and trueness (relative bias ≤ 2.6%; relative bias ≤ 1.4%) were obtained for low (10–25 mg/L AA for methanol and 2–10 for othervolatiles) and high (25–5000 mg/L AA for methanol and 10–5000 for other volatiles) ranges of concentrations, correspondingly. Conclusions: The method increases the reliability of measurements and eliminates manual proceduresof internal standard addition into both calibrationstandard solutions and spirit drinks.

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