Liquid chromatographic determination of free and total sulphites in fresh sausages

The present work describes a method for the determination of free and total sulphite in fresh sausages and its implementation on 48 samples. The method includes the extraction of sulphite, both free and total, by dissolution of the sample in a suitable solvent and determination by high performance liquid chromatography with electrochemical detection. The method is that previously reported by Kim and Kim (J Food Sci 51 1986 1360–1361) improved by certain modifications the principal of which consists of working atpH 10 for the extraction of total sulphite. Use of this pH permits reversible dissociation of the combined sulphite. In reproducibility assays carried out on sausages, variation coefficients of 3.3 and 5% were obtained for free and total sulphite, respectively. To evaluate recovery, sulphite was added to the samples as hydroxymethylsulphonate. Mean recovery was 86.4% with a variation coefficient of 3.8%. In 62% of the sausages analysed, amounts of total sulphites higher than 450 μ SO₂ g^?1 were found. Among the samples, considerable variation was observed in the distribution of sulphite between the free and combined forms.