Determination of Ethanol Content in Alcoholic Beverages by Using Partition Coefficient and Gas Chromatographic Technique

Abstract

The partition coefficient (K) between liquid-gas phases of ethanol could be easily obtained bypreparation of two identical vials filled with ethanolic solutions of different volumes. The headspacesamples were collected and injected into a gas chromatograph. The K obtained by solving twomathematic equations for pure ethanolic solution equilibrated at 50 °C for 30 minutes was 3.013.

The obtained K value was then used to determine ethanol concentration in 25 brands ofalcoholic beverages. Without requiring any internal or external standardization, it was found that theconcentration of ethanol was approximately the same as they were labeled on the bottles. In thisstudy, sucrose (2 %w/v) in the ethanolic solution did not affect the K value. The maximum concentrationof ethanol injected into a GC equipped with FID detector was still linear at 12 %(v/v). Thus, it wasconcluded that the proposed method was simple and accurate.

Keywords : Alcoholic Beverage / Ethanol / Gas Chromatography / Headspace Technique /Partition Coefficient