Abstract
A simple method is described for the determination of a major organic acid oxalate in vegetables. The method involves homogenization of specimens in ice-cold water and 3N HCl for the extraction of water-soluble and total oxalate, respectively, and subsequent analysis of the extracts by capillary isotachophoresis using 0.01N HCl: β-alanine (pH 4.0) and 0.01N n-caproic acid (pH 3.4) as leading and terminal electrolytes, respectively. Other major organic acids also separated by this method were oxalacetic, α-ketoglutaric, citric and succinic acids. Oxalate was confirmed by the disappearance of corresponding zone and the concomitant apperance of formate zone in the isotachophoregram for the specimens treated with oxalate decarboxylase. The calibration curve was linear over the range of 0 to 20 nmol per μl of standard mixture. Oxalate and calcium contents of 13 vegetables have been compared. Water-soluble oxalate in spinach could be leached out in boiling water.
