Abstract
The effect of ethanol addition on the determination of thiosulfate based on the reduction of Ce(IV) and fluorescence detection of Ce(III) was investigated by flow-injection analysis. It was found that the sensitivity of thiosulfate detection was significantly increased by injecting thiosulfate into a mixed solution of Ce(IV) and ethanol, rather than a solution of Ce(IV) alone. This is probably due to trace amounts of thiosulfate accelerating the rate of reduction of Ce(IV) by ethanol: Ce(IV) is slowly reduced by ethanol in the absence of thiosulfate, and thiosulfate serves as a catalyst to the reduction. The detection limits as S/N = 3 for thiosulfate were very low (10−9 M level).
