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Abstract
Determination of small amounts of polybasic and hydroxy acids in biological materials by gas-liquid chromatography was investigated. Extraction of free acids from their aqueous salt solution was conducted with methanol by treating the solution with Dowex 50 (H+) The free acids obtained were esterified with diazomethane in the presence of 2,2-dimethoxypropane. The ester solution was concentrated under reduced pressure with an aspirator at room temperature. Finally, the concentrate, after mixing with an internal standard ester, was injected into a gas-liquid chromatograph with a hydrogen flame ionization detector. Succinic, adipic, malic, mesaconic, citric, mevalonic, and 3-hydroxy-3-methylglutaric acids were found to be determinable by the present method with a high accuracy.