DETERMINATION OF TARTARIC, MALIC, AND CITRIC ACIDS IN GRAPE JUICE AND WINE USING GRADIENT ION CHROMATOGRAPHY

A gradient ion chromatographic (IC) method with conductivity detection and chemical suppression was evaluated for the separation and quantification of major organic acids in grape juice and wine without prior sample clean-up. Tartaric, malic, and citric acids were the major acids of concern in this investigation. By using a Dionex OmniPac PAX-500 column, sample preparation was a simple 50-fold dilution with 0.45 micron filtration and direct injection. Analysis time was 35 minutes. The accuracy of the IC method was better than +/- 1.0% at the 2.5 g/L concentration level. The precision for a dark red juice was +/- 2.0%. The results of the IC method were comparable to other published colorimetric and enzymatic methods. This IC method enables rapid and simultaneous analysis of tartaric, malic, and citric acids in grape juice and wines for quickly assessing the stability of products during manufacturing processes.