Determination of Six Organic Acids in Hami Jujube During Drying by HPLC

A method for the determination of organic acids in Hami jujube was established. Chromatographic conditions:WondaSil C₁₈-WR column (4.6 mm×50 mm, 5 μm) was used for separation. The mobile phase was KH₂PO₄ buffer solution of 0.05 mol/L:methanol=9:1, pH=2.3, flow rate was 0.8 mL/min, column temperature was 35℃, detection wavelength was 210 nm, injection volume was 20 μL. Under these conditions, oxalic acid, malic acid, tartaric acid, citric acid, fumaric acid and succinic acid could be separated. The results showed that the content of malic acid was the highest and succinic acid was not detected. During the natural drying process, the contents of the five organic acids decreased first and then increased. The malic acid content decreased to the lowest 7.58 mg/g on the 4th day and the highest 10.15 mg/g on the 12th day.During the process of hot air drying at 45℃, the total organic acids decreased first and then increased, and highest content of malic acid was 10.41 mg/g.