RÉSUMÉ
Objective To improve the detection ability of laboratories, and to identify possible technical defects in the detection of dichloroacetic acid and trichloroacetic acid in drinking water. Methods A number of laboratories were organized to conduct interlaboratory determination of dichloroacetic acid and trichloroacetic acid in drinking water. Prefabricated standard series and intermediate samples were distributed. Data of determination were collected and statistically analyzed to evaluate the detection results. Results The slopes of dichloroacetic acid and trichloroacetic acid working curves were analyzed by Grubbs test. The analysis results showed that there were 1 outlier in the dichloroacetic acid data and 3 outliers in the trichloroacetic acid data, respectively. The determination results of the spiked samples of dichloroacetic acid and trichloroacetic acid were 1.5 and 4 times the actual value, respectively. Conclusion This investigation reveals that there exist some technical problems in the direct determination of dichloroacetic acid and trichloroacetic acid by gas chromatography, such as inappropriate selection of chromatographic conditions and injection port flow control, and incorrect way of spiking internal standards.