Gas chromatographic separation and determination of chloroacetic acids in water by a difluoroanilide derivatisation method

Abstract

A simple method for the micro-determination of chloroacetic acids in water was developed. Chloroacetic acids in a water sample were converted into the difluoroanilide derivatives by reaction with difluoroaniline and dicyclohexylcarbodiimide. The derivatives were extracted into ethyl acetate, cleaned up and determined by gas chromatography with electron-capture detection. The detection limits for monochloroacetic, dichloroacetic and trichloroacetic acids were ca. 2, 1 and 0.6 µg l^–1, respectively, in a 50-ml water sample. A pre-treatment method involving the use of an ion-exchange resin is also described, which allows determination at lower levels. The method was applied to the determination of chloroacetic acids in chlorinated water.