Determination of Organic Acid in Wipe Grapes Based on Ion Exchange-conductivity Detection Method

KeyWord:ion exchange-conductivity detection  organic acids  wipe grapes

Abstract:

      A novel ion chromatographic method was developed for the determination of organic acids in wipe grapes,including lactic acid,propionic acid£¬DL-malic acid£¬D-tartaric acid£¬oxalic acid£¬citrate£¬succinic acid and ascorbic acid.The samples were prepared through extraction decoloration and filtration before analysis,and eluted with 1.5-30 mmol/L KOH produced by an eluent antogenerator.The interference between the coexistence ions which were not examined and adjacent ions was investigated.The results showed that the unexamed inorganic ions made no interference on determination.The eight organic acids showed good linear relationship between mass concentration and peak area in the certain concentration ranges.The detection limits were in the range of 0.064-0.25 mg/L and the average recoveries were 89.5%-96.2%.The method was applied in the determination of eight organic acids in wine grapes from eastern Helan mountain£¬Ningxia.The results showed that eight organic acids were all detected in wine grapes with high contents of DL-malic acid and D-tartaric acid£¬citric acid£¬and low contents of other acids.The wine grapes is a typical tartaric acid fruit.