Rapid Separation of Antioxidants in Food Samples by Coelectroosmotic CE

Rapid separation of a group of eight antioxidants by coelectroosmotic capillary electrophoresis and their preliminary determination in foods (cereal, wine, and beer) is described. The compounds studied were protocatechuic acid, salicylic acid, p-hydroxybenzoic acid, vanillic acid, syringic acid, p-coumaric acid, ferulic acid, and sinapic acid. The best separation was achieved by use of a running buffer consisting of 125 mM boric acid, 49 mM disodium hydrogen phosphate, 0.002% (w/v) hexadimethrine bromide, and 2.5 mM α-cyclodextrin, at pH 7.5; the analysis time was less than 3.5 min. Ligration time and peak area reproducibility, studied on the same day (n=4) and on three different days (n=12), showed the method is reproducible. A study of the antioxidant content of cereal, wine, and beer samples was conducted to evaluate the usefulness of the method. Antioxidants were extracted from cereal samples by sonication with methanol and from wine and beer samples by solid-phase extraction with C₁₈ cartridges. This preliminary study showed that seven of the eight compounds could be detected in wine and cereal samples whereas only five were detected in beer samples.