The simultaneous separation and determination of five organic acids in food by capillary electrophoresis

The simultaneous separation of quinic acid, anisic acid, salicylic acid, benzoic acid and sorbic acid was performed by capillary electrophoresis with 20 mmol L−1 NaOH–20 mmol L−1 H3BO3 (pH 8.8) as the background electrolyte. The choices of the background electrolytes and the applied voltage were optimized. The effects of tetrabutylammonium bromide and sodium dodecylsulfate on the separation were investigated in detail. Under the optimum condition, the linearity, reproducibility and detection limit of five organic acids were shown, respectively. As an application of the method proposed, 10 samples of soy sauce and vinegar were analysed to determine benzoic acid and sorbic acid. The procedure described provides the advantages of good selectivity, rapid speed and simplicity for the separation and determination of organic acids.