Comprehensive headspace gas chromatographic analysis of denaturants in denatured ethanol

To discourage consumption, ethanol is often denatured using both volatile (e.g., methyl ethyl ketone and isopropanol) and nonvolatile (e.g., denatonium benzoate) chemical substances. As a result, the analysis of denatured ethanol samples is usually performed by multiple techniques such as gas chromatography for the volatile denaturants and liquid chromatography for the nonvolatile ones. However, the need for multiple techniques increases the cost of analysis and forms a severe obstruction for on-site product control. Using the full evaporation technique combined with gas chromatography and flame ionization detection, only one analytical methodology has to be used here to determine both volatile and nonvolatile denaturants in denatured ethanol. Denatonium benzoate is determined as benzyl chloride following an in-vial reaction. Compared to conventional techniques, the novel method performs equally well, but it is simpler to apply. At the same time, drawbacks of alternative methods are circumvented such as equilibration issues and alterations to the stationary phase when using liquid chromatography with ion pairing agents or matrix effects when applying static headspace gas chromatography. The developed method showed good linearity, repeatability, and recovery toward all analytes and was applied to the analysis of commercial denatured ethanol for disinfection and ethanol-based windscreen washer fluids.