Determination of chlorinated acetic acids in drinking water by in-situ derivatization and solid phase microextraction

A method is described for the determination of chlorinated acetic acids in water. The method employs in situ derivatization of the acids to their methyl esters using HCl and methanol, followed by solid phase microextraction and quantitation by GC/ECD. Optimized Ones of derivatization, adsorption and desorption have been determined. Formation of chloroform from decarboxylation of trichloroacetic acid is minimized by choice of reaction time, thereby maximizing formation of the trichloroacetic acid methyl ester. Detection limits are in the low mu g/L range for the di-and trichloroacetic acids due to the efficient adsorption of their esters on the SPME fiber, and the large response of the ECD to these species. Recoveries are similar to those found using EPA method 552.