Simultaneous determination, by capillary zone electrophoresis, of multiplecomponents of different industrial products

Four parabens (esters of 4-hydroxybenzoic acid), effective preservatives ag ainst the growth of bacteria, yeast, and mold in numerous industrial produc ts, have been used in this work as model compounds to demonstrate the resol ving power of capillary electrophoresis (CE). The simultaneous determinatio n of methyl- (MP), ethyl- (EP), propyl- (PP), and butylparaben (BP) was ach ieved by capillary zone electrophoresis (CZE) with UV diode-array detection at 294 nm. When run voltage, temperature, and electrolyte concentration an d pH were optimized the most effective separation was achieved within 7 min by use of 50 cm (effective length) fused silica capillary tubing and opera tion at 25 kV and 20 degreesC. Background electrolyte comprising 35 mM tetr aborate buffer adjusted to pH 10.0 gave the best results. The limits of det ection of the optimized method ranged from 0.65 mug mL(-1) for BP to 0.81 m ug mL(-1) for MP; the relative standard deviation was between 0.35 and 0.50 %. These results showed that the method enables the determination of the fo ur parabens in commercially available cosmetic and pharmaceutical preparati ons containing some of the parabens and in an unidentified canned berry fru it juice.