Automated determination of sulphite by gas-phase molecular absorption spectrometry

Abstract

Conditions for the automated determination of sulphite in aqueous solution based on measuring the absorbance of sulphur dioxide evolved upon acidification of samples are described. The proposed method has a detection limit of 0.20 µg ml^–1 and relative standard deviations of 2.3 and 1.8% for 20 and 10 µg ml^–1 of sulphite, respectively. The calibration graph is linear up to 120 µg ml^–1 and samples can be analysed at the rate of 20 per hour. The method has been applied to the determination of sulphur dioxide in synthetic samples and in white wines.