Sensitive determination of ethanol in low-alcohol samples by ion-exclusion chromatography with EC detection using a ruthenium-based inorganic film electrode

Ethanol in real matrices was determined by ion-exclusion chromatography (IEC) with electrochemical detection at a glassy carbon electrode coated with conducting films of mixed-valent ruthenium oxide cross-linked with ruthenium cyanide (mvRuO-RuCN). These films exhibit very high and persistent elecrocatalytic behavior toward oxidation of hydroxyl-containing compounds, and offer attractive features for applications as electrocatalytic amperometric sensor in acidic media. Real samples such as vinegar and low-alcohol beers were simply diluted with mobile phase (1:10), filtered and injected without extensive sample treatment. A polymeric-based hydrogen-form ion-exclusion column was chosen for the chromatographic separations using 25-mM sulphuric acid as the mobile phase. The response was linear for sample solutions containing ethanol up to 0.1 M with a dynamic range of more than three orders of magnitude.