Rapid and Selective Determination of Trace Benzimidazole Fungicides in Fruit Juices by Magnetic Solid-Phase Extraction Coupled with High-Performance Liquid Chromatography-Fluorescence Detection

In this paper, a new method was established for the determination of benzimidazole fungicides in fruit juices by magnetic solid-phase extraction coupled with high-performance liquid chromatography-fluorescence detection. The extraction adsorbent was synthesized to form a core-shell Fe3O4@SiO2 structure surface functionalized with benzenesulfonic acid. The negative charges of the benzenesulfonic acid groups can promote strong electrostatic interaction with positively charged analytes to exhibit efficient and selective extractive ability. After the extraction, the magnetic adsorbent can be rapidly isolated from the matrix by an external magnet. Main factors influencing the extraction efficiency including amount of adsorbent, solution pH, extraction time, and volume of desorption solution were studied and optimized. Under the optimal conditions, recoveries of the spiked samples ranged from 83 to 96 % with the relative standard deviations lower than 10 %. The limits of detection were 0.55 and 0.14 mu g kg(-1) for carbendazim and thiabendazole, respectively. The proposed method was successfully applied for selective and efficient determination of benzimidazole fungicides in various juice samples.