Portable battery-powered flow injection analyser for volatile alcohols using semiconductor gas sensors

The response characteristics of Taguchi TGS812 and TGS824 type semiconductor gas sensors were evaluated for flow injection monitoring of alcohol concentrations in liquid samples. The detection method was based on the head space analysis of vapour above aqueous samples containing ethanol. A low cost, hand-held monitor has been developed for this application in which an air carrier stream is pumped through a twin sensor cell. Different sensitivities to aqueous ethanol samples were observed at each sensor. Analysis of commercial liquor samples such as beers, wines and liqueurs showed a correlation coefficient as high as 0.9999 in comparison with gas chromatography analysis. This system is therefore applicable as a portable, hand-held flow injection monitor for process control during production and for monitoring the quality of products containing ethanol.