Determination of Sulfonylurea Herbicides in Pears Using Hollow Fiber-Protected Magnetized Solvent-Bar Liquid-Phase Microextraction HPLC

Hollow fiber-protected magnetized solvent-bar liquid-phase microextraction of sulfonylurea herbicides, including nicosulfuron, bensulfuron-methyl, pyrazosulfuron and chlorimuron-ethyl, in pears was developed. The analytes were determined by high-performance liquid chromatography. This present method has the advantages of stir bar sorptive extraction and hollow fiber-protected solvent-bar microextraction, that permits active magnetic stirring, extraction and preenrichment in a single device simultaneously. The magnetized solvent-bar was easily retrieved after extraction with a magnet, so the extract is conveniently collected. Experimental parameters, including type of extraction solvent, the number of magnetized solvent-bars, extraction temperature and time, stirring speed, pH of the sample solution, and the salting-out effect, were investigated and optimized. Under optimal experimental conditions, the calibration curve showed good linearity (r a parts per thousand yen 0.9998). The limits of detection and quantification were in the range of 7.15-8.26 ng/g and 24.99-27.52 ng/g, respectively. The recoveries were in the range of 80.08-105.56 %, and the relative standard deviations were lower than 6.82 %. The results showed that the present method was a satisfactory method for the determination of sulfonylurea herbicides in pears.