SIMULTANEOUS DETERMINATION OF ORGANIC-ACIDS AND INORGANIC ANIONS IN BEVERAGES BY ION-EXCHANGE CHROMATOGRAPHY

A longer anion-exchange column (A-PW125, 4.6 mm i.d. X 125 mm) was made using TSKgel IC Anion-PW resin (TOSOH) in order to achieve a simultaneous determination of organic acids and inorganic anions in beverages. The number of theoretical plates obtained from a shorter column (A-PW50, 4.6 mm i.d. X 50 mm) and A-PW125 to Cl-were 1724 and 3906, respectively. Separation of malonic acid from NO2- and fumaric acid from the system peak have not been achieved by an A-PW50 column. When a 3.0 mM potassium biphthalate eluent was used at a flow rate of 1.0 ml/min, fifteen anions were separated by an A-PW125 column with a good resolution within 50 min. The detection limits obtained by this method were 1.0-7.1 ppm (mug/ml) for organic acids, and 0.17-0.83 ppm for inorganic anions. This method was applied for the simultaneous determination of organic acids and inorganic anions in wine and apple juice samples, and for a purity determination of DL-malic acid.