Determination of sulfonylurea herbicides in water samples by high performance liquid chromatography coupled with on-line magnetic solid phase extraction using trimethylstearylammonium-bromide-modified magnetic particles

: A magnetic particle with a trimethylstearylammonium-bromide-modified surface was prepared as an adsorbent by a sol-gel method. An on-line magnetic solid phase extraction (MSPE) device was established and used for extraction and preconcentration of two sulfonylurea herbicides (SUHs) (chlorsulfuron and bensulfuron-methyl) in water samples prior to high-performance liquid chromatography. On-line MSPE parameters were optimized, including desorption conditions, adsorbent dose, pH of the sample solution, and injection flow rate. Under the optimum conditions, satisfactory linearity was obtained (correlation coefficients ≥ 0.9997). The limits of detection (LODs) of chlorsulfuron and bensulfuron-methyl were 0.32 and 1.12 μg/L, respectively. The method was successfully applied to determine two sulfonylurea herbicides in three types of environmental water samples. The recoveries of sulfonylurea herbicides were in the range of 70.0%-113.4%. The results confirmed that this method is efficient and simple and has a wide application potential in separation and enrichment of sulfonylurea herbicides in environmental water samples.