Objective To establish a method for the determination of alachlor, acetochlor, pretilachlor, butachlor, propisochlor and metolachlor in drinking water and source water by gas chromatography-mass spectrometry (GC-MS).

Methods Six amide herbicides in water samples were extracted by a C₁₈ solid-phase extraction column and eluted with ethyl acetate. The eluent was dehydrated, concentrated to a fixed volume, and then separated and determined by GC-MS. A qualitative analysis was performed based on the retention time and mass spectrum of the substance to be determined, and a quantitative analysis was performed by the quantitative ion external standard method.

Results This method had a good separation effect, and the concentration range was 5.0-250 μg/L on the determination curve, if 500 mL water sample was concentrated to 1.0 mL, the limit of detemination was 0.01 μg/L. When the spiked concentrations of the samples were 0.02, 0.20 and 0.50 μg/L, respectively, the recoveries of the method ranged from 78.6% to 106.4%, and the relative standard deviations were between 1.7% and 6.8% for six consecutive measurements. The stability of the components to be determined in water was studied, and the results showed that accurate results were obtained after the samples were stored at 4 ℃ for 24 hours.

Conclusion The method is simple and highly sensitive and can be used for the determination of six amide herbicides in drinking water and source water.