Determination of Herbicides in Soil by Dispersive Solid-Phase Extraction, Dispersive Liquid–Liquid Microextraction, and High-Performance Liquid Chromatography

A method for determination of five herbicides (i.e., quinclorac, metsulfuron-methyl, bensulfuron-methyl, atrazine, prometryn) in soil was developed by dispersive solid-phase extraction combined with dispersive liquid–liquid microextraction and high-performance liquid chromatography. The analytes were removed from the soil by liquid partitioning with acetonitrile/5% acetic acid, purified using a octadecylsilane sorbent, and subsequently extracted before chromatographic analysis. Under the optimized conditions, the linear dynamic range was from 10.0 to 300 ng g−1 with correlation coefficients (r) between 0.9971 and 0.9985. The limits of detection were between 1.5 and 3.1 ng g−1, with relative standard deviations from 3.8% to 6.7% (n = 5). The recovery of the herbicides from soil at fortification levels of 20.0 and 100.0 ng g−1 were between 71.5% and 94.3%. The method was successfully applied to the determination of the analytes in soil.