Abstract
A Gas chromatographic determination of organic acids added in common salt has been developed. Malic acid and citric acid added in sodium chloride were easily extracted with acetone. Then, this solvent layer was separated, and evaporated to dryness. After this treatment the sample was converted directly to trimethylsilyl derivatives withN, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA), and this product was analysed on colomn (1m×3mm) packed with 2% of OV-17 on Chromosorb G (AW-DMCS){(60-80) mesh} and operated with temperature programing from 100°C to 230°C at 10°C/min. When tartaric acid was used as internal standard substance, the retention time and recovery rate of malic acid were 4.7 min and 105% and of citric acid were 9.1 min and 106% respectively. Working curve of malic acid or citric acid using tartaric acid as internal standard substance was rectilinear in the range of ratio from 0.02 to 0.08% in common salt. The reproducibility of the determination of malic acid within above range of concentration was 1.2% as coefficient of variation, and of citric acid was 2.2% respectively. Impurities like calcium, magnesium, potassium, iron, copper and aluminium which contained in common salt did not interfere.“Tsukemonoyouen” on the market was analysed by this method and its results showed 0.05% for malic acid and 0.04% for citric acid respectively.
