Determination of Organic Acids in White Wines by RP-HPLC

Summary The chromatographic conditions for the optimal separation of tartaric, malic and citric acids on a LiChrosorb RP-18 column (10 m, 25 cm x 4.0 mm i.d.) at 210 nm were determined. The optimized RP-HPLC method (mobile phase: c(H3PO4 )=6 10 –3 mol/L, pH = 2.1, flow rate 1.0 mL/min) was validated. Calibration curves were linear for all three acids in the concentration range tested; r 2 was better than 0.999. RSDs for tartaric and malic acids were within 2 %, and for citric acid 10.4 %. The average relative error for tartaric acid was 3.2 %, for malic acid 2.5 % and for citric acid 6.0 %. Ethanol caused an insignificant negative response at tR = 5.69 min, whereas glucose and fructose eluted in the void volume. According to the validation results, and from analysis of wine samples, the described HPLC method was found adequate for routine determination of tartaric and malic acids and to some extent also of citric acid in dry, semi-dry, semi-sweet and sweet white wines.