Objectives  To develop an analytical method for 2,4-dichlorophenoxyacetic acid (2,4-D) and bentazone in drinking water by using dichloromethane extraction and gas chromatography.

Methods  The amounts of 2,4-D and bentazone in water samples were detected by dichloromethane extraction and capillary column gas chromatography with electron capture detector through controlling the temperature of derivatization.

Results  The working curves for 2,4-D and bentazone detection showed good linearity in the range of 0.5~25.0 μg/L and 0.7~25.0 μg/L respectively, with a correlation coefficient of 0.999. The minimum detection concentration for 2,4-D was 0. 5 μg/L and that for bentazone was 0.7 μg/L. The recoveries of 2,4-D and bentazone at three spiking levels were in the range of 82.0%~89.6% and 91.1%~94.4% respectively, and RSDs were in the range of 1.3%~2.3% and 0.36%~1.7%, respectively. The response value in 10℃~15℃ was obviously better than that in 15℃~20℃(P<0.05).

Conclusions  The sensitivity and precision of the method on detecting 2,4-D and bentazone in water by dichloromethane extraction and derivatization between 10℃ and 15℃ could meet the requirement of the national standard.