The determination of ethanol in official drug preparations. Part I. A Comparison of distillation and gas-chromatographic methods

Abstract

A gas-chromatographic method has been compared with the official methods for the determination of ethanol in a wide range of drug preparations. The gas-chromatographic determinations were performed with a column packed with 5 per cent. Nonidet P40 (an alkylphenol-ethylene oxide condensate) on 30 to 40-mesh Teflon 6, a column temperature of 70° C, nitrogen as the carrier gas and a flame-ionisation detector. Propanol was used as an internal standard and the ethanol contents of 101 drug preparations were determined by comparing the ratios of the heights of the ethanol and propanol peaks on the chromatograms of the preparations with those of standards. An over-all standard deviation of 0·16 was obtained, which compared favourably with an over-all standard deviation of 0·17 when the same preparations were assayed for ethanol by using the official methods. The accuracy of the gas-chromatographic method was at least as good as the official methods and was superior for those drug preparations that required the use of the more complex official methods involving light petroleum extractions.