Determination of clamidoxic acid in serum by gas-liquid chromatography

Abstract

A method has been developed for the determination of clamidoxic acid [2-(3,4-dichlorobenzamido)phenoxyacetic acid] in serum by using gas chromatography with electron-capture detection. Clamidoxic acid is extracted from acidified serum into toluene and returned to an aqueous sodium hydroxide phase. The amide is hydrolysed to 3,4-dichlorobenzoic acid which, after acidification, is extracted into toluene containing an internal standard. The acid is converted into its methyl ester by the addition of a solution of diazomethane in diethyl ether, excess of diazomethane is destroyed with acetic acid, and an aliquot analysed.