The determination of higher alcohols in potable spirits: comparison of colorimetric and gas-chromatographic methods

Abstract

Gas chromatography of brandies and whiskies shows that n-propanol, isobutanol, 2-methylbutan-1-01 and 3-methylbutan-1-01 comprise the major proportion of the higher alcohols. The furfural method for determining higher alcohols described in the Report of the Royal Commission on Whisky and Other Potable Spirits, 1909, gives results in excess of the sum of these alcohols determined by gas chromatography, but the method of the Association of Official Agricultural Chemists, which involves the use of p-dimethylaminobenzaldehyde, gives results that agree well with those obtained by gas chromatography.IN his evidence to the Royal Commission on Whisky and Other Potable Spirits 1908-1909, Dr. T. E. Thorpe, then Government Chemis.t, described a method for determining higher alcohols in potable spirits based on the colour formed by the action of furfural and sulphuric acid. The method had been developed under Dr. Bell, the previous Government Chemist, to meet the need for a rapid method suitable for examining samples submitted by H.M. Customs & Excise. Since that time, the met'hod has been further described by Simmondsl and Nicholls,2 and has gained a semi-official status in this country. Consistent results are not easily obtained without long practice, and discrepancies between results obtained in different laboratories prompted an investigation by Osborn and M ~t t , ~ who recommended several changes, the most important being the use of heat for developing the colour. When applied to samples of commercial spirits, this modification, however, was found by this

Whisky analysis

“…The spectrophotometric and titrimetric methods from the pre-chromatography era (Shoeneman and Dyer, 1973;Singer and Styles, 1965) are now all but redundant and only occasionally required for use in supporting dated regulatory requirements. For example, it may be used to monitor the efficiency of rectification in the continuous stills used to distil Scotch grain spirit and Canadian grain neutral spirits (GNS), in competitor product analysis to determine the percentage malt whisky in a blended Scotch whisky, and in consumer protection activity to confirm brand authenticity.…”

Food

“…Some volatile constituents of Passion fruit wane were reported by Muller et al ( 690). The gas chromatographic determination of various higher alcohols in alcoholic beverages has been performed by Prillinger and Horw'atitsch (75G) and Singer and Stiles (870,88G). Isomeric farnesols were separated from grape and other fruit brandies by thin layer chromatography (980).…”