Comparison of Various Preparation Methods for Determination of Organic Acids in Fruit Vinegars with a Simple Ion-Exclusion Liquid Chromatography

An ion-exclusion liquid chromatography with mobile phase 0. 005 mol L -1 H 2SO 4 and step flow rate gradient (0. 2 mL min -1 in the first 40 min and 0.5 mL min -1 from 41 to 60 min) was used to determine 20 organic acids simultaneously at 17 °C within 51 min. The peak resolutions (Rs) were 0.45~3.02 and separation factors (α) were all higher than 1. Impurities in fruit vinegar executed with direct injection or C18 cartridge clean-up for analysis would influence the glutaric and oxalic acid measurement; however, SAX cartridge extraction could reduce the interferences (organic acid recoveries were 93.93~99.98%). Acetic, ascorbic, citric, malic, and malonic acids were the major organic acids in fruit vinegars (apple, apple sparkling, plum, cranberry, and grape).