Analysis of food additives by capillary electrophoresis

A simple and rapid capillary zone electrophoretic method is proposed for the analysis of antioxidants and preservatives in food. The important factors affecting separation and detection, for example pH, and concentration of the buffer electrolyte and organic modifier, were investigated in detail. Separation of five antioxidants (propyl gallate, gallic acid isoamyl ester, gallic acid n-octyl ester, nordihydroguaiaretic acid, and trihydroxybutyrophenone) and one preservative (benzoic acid) was achieved in a 50.5 cm (effective length) × 75 μm i.d fused-silica capillary, with 15 mmol L–1 borate buffer, pH 9.18, containing 25% (v/v) acetonitrile as separation buffer. UV detection was at 219 nm and the applied potential was 25 kV. Regression analysis revealed linear relationships between peak area and amount of each additive from 10 to 1000 μg mL–1 (R = 0.9992–1.0000). RSD of retention time and peak area were 0.44–0.74% and 1.25–4.31%, respectively. The method was successfully used for simultaneous analysis of the six compounds in food with the recoveries from 89.3 to 115.8%.