Determination of parabens in sweeteners by capillary electrochromatography

Parabens, common food preservatives, were analysed by capillary electrochromatography, using a commercial C18 silica (3 mu m, 40 cm x 100 mu m i. d.) capillary column as separation phase. In order to optimise the separation of these preservatives, the effects of mobile phase composition on the separation were evaluated, as well as the applied voltage and injection conditions. The retention behavior of these analytes was strongly influenced by the level of acetonitrile in the mobile phase. An optimal separation of the parabens was obtained within 18.5 minutes with a pH 8.0 mobile phase composed of 50:50 v/v tris(hydroxymethyl)aminomethane buffer and acetonitrile. The method was successfully applied to the quantitative analysis of paraben preservatives in sweetener samples with direct injection.