Rapid determination of amide herbicides in environmental water samples with dispersive liquid-liquid microextraction prior to gas chromatography-mass spectrometry.

This paper describes a novel, simple and environmentally friendly method for rapid determination of the amide herbicides metoalchlor, acetochlor, and butachlor. It is based on dispersive liquid-liquid microextraction and gas chromatography-mass spectrometry. Factors that may influence the enrichment efficiency, such as type and volume of extraction solvent, type and volume of dispersive solvent, extraction time, and content of NaCl, were investigated and optimized in detail. Under the optimum conditions, the limits of detection of metoalchlor, acetochlor, and butachlor were 0.02, 0.04, and 0.003 microg L(-1), respectively. The experimental results indicated that there was linearity over the range 0.1-50 microg L(-1) and good reproducibility with relative standard deviations over the range 1.6-3.0% (n = 5). The proposed method has been applied for the analysis of real-world water samples, and satisfactory results were achieved. Average recoveries of spiked herbicides were in the range 80.3-108.8%. All of these indicated that the developed method would be an efficient method for simultaneous determination of the three herbicides in environmental water samples.