Determination of low-molecular-mass anionic compounds in beverage samples using capillary zone electrophoresis with simultaneous indirect ultraviolet and conductivity detection

Abstract

The determination of low-molecular-mass anionic components in beer samples using capillary zone electrophoresis with simultaneous direct conductivity and indirect UV detection is described. Optimization of the carrier electrolyte composition has been performed taking into account parameters such as pH as well as those that were found to be crucial for its compatibility with both detection principles employed in this paper. The latter are UV absorptivity, electrophoretic mobility of the buffer co-ion and the buffer co-ion concentration, which strongly influence the quality (signal-to-noise ratio, chromatographic resolution of adjacent peaks) of the electropherogram. Best results could be achieved with a carrier electrolyte consisting of 4-aminobenzoic acid, tetradecyltrimethylammonium bromide electroosmotic flow reversal and a pH of 5.75, adjusted using histidine. Using this carrier electrolyte, limits of detection ranging from 0.218 mg l −1 for pyroglutamate down to 0.018 mg l −1 for chloride could be obtained.