Analysis of haloacetic acids in water by a novel technique: simultaneous extraction– derivatization

A simple and novel method has been developed for the analysis of haloacetic acids (HAAs), disinfection by-products (DBPs) formed during water chlorination. This method can be used to determine six of these acids, including chloro, bromo and chloro/bromo acids. The validity and reliability of the method were tested over 6 months on twenty French water samples. 50 ml of water are percolated over an ion-exchange resin, the strong acids are trapped and then eluted and simultaneously esterified to give their methyl derivatives by a methyl alcohol solution acidified with sulfuric acid. The esters are extracted by cyclohexane and analyzed by gas chromatography with electron-capture detection (GC/ECD). Dalapon is used as a tracer in order to monitor the extraction process and trichloropropane as the internal standard. The detection limits for the HAAs analyzed are between 0.1 μg/l and 0.2 μg/l. The analysis of different water samples showed that all the haloacetic acids, except monobromoacetic acid, were present. The total HAAs in water originating from surface waters was less than 50 μg/l, but could exceed 100 μg/l for water originating from reservoir waters. In underground waters, the concentration of HAAs was negligible.