title: Determination of four sulfonylurea herbicides in tea by matrix solid-phase dispersion cleanup followed by dispersive liquid-liquid microextraction.
abstract: Matrix solid-phase dispersion combined with dispersive liquid-liquid microextraction has been developed as a new sample pretreatment method for the determination of four sulfonylurea herbicides (chlorsulfuron, bensulfuron-methyl, chlorimuron-ethyl, and pyrazosulfuron) in tea by high-performance liquid chromatography with diode array detection. The extraction and cleanup by matrix solid-phase dispersion was carried out by using CN-silica as dispersant and carbon nanotubes as cleanup sorbent eluted with acidified dichloromethane. The eluent of matrix solid-phase dispersion was evaporated and redissolved in 0.5 mL methanol, and used as the dispersive solvent of the following dispersive liquid-liquid microextraction procedure for further purification and enrichment of the target analytes before high-performance liquid chromatography analysis. Under the optimum conditions, the method yielded a linear calibration curve in the concentration range from 5.0 to 10 000 ng/g for target analytes with a correlation coefficients (r(2)) ranging from 0.9959 to 0.9998. The limits of detection for the analytes were in the range of 1.31-2.81 ng/g. Recoveries of the four sulfonylurea herbicides at two fortification levels were between 72.8 and 110.6% with relative standard deviations lower than 6.95%. The method was successfully applied to the analysis of four sulfonylurea herbicides in several tea samples.
authors: Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, P. R. China.
authors: Pei
authors: P
authors: Liang
authors: Jinjin
authors: J
authors: Wang
authors: Guojiao
authors: G
authors: Liu
authors: Jinyan
authors: J
authors: Guan
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005506:Food Contamination / Q000032:analysis; D006540:Herbicides / Q000032:analysis / Q000302:isolation & purification*; D059627:Liquid Phase Microextraction / Q000379:methods*; D052616:Solid Phase Extraction / Q000379:methods*; D013453:Sulfonylurea Compounds / Q000032:analysis / Q000302:isolation & purification*; D013662:Tea / Q000737:chemistry*
chemical_list: D006540:Herbicides; D013453:Sulfonylurea Compounds; D013662:Tea
keywords: Dispersive liquid-liquid microextraction; High-performance liquid chromatography; Matrix solid-phase dispersion; Sulfonylurea herbicides; Tea samples