High-Performance Liquid Chromatographic Determination of Diazinon after Its Magnetic Dispersive Solid-Phase Microextraction Using Magnetic Molecularly Imprinted Polymer

A magnetic molecularly imprinted polymer (MMIP) was successfully synthesized and applied as the sorbent in the magnetic dispersive solid-phase microextraction (MDSPME) to separate and preconcentrate diazinon from real samples prior to its determination by high-performance liquid chromatography with ultraviolet detector (HPLC-UV). The MMIP was prepared by one-step surface imprinting technique using precipitation polymerization method without any use of surfactants or stabilizers. The functionalized Fe3O4 nanoparticles were used as the magnetic supporter, diazinon as the template, methacrylic acid (MAA) as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. The synthesized MMIP was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) spectroscopy, and Brunauer-Emmett-Teller (BET) analysis. The selectivity study demonstrated that the MMIP had high affinity toward diazinon compared to other organophosphates (fenitrothion and chlorpyrifos). Various parameters affecting the efficiency of extraction such as sorption and desorption time, amount of sorbent, type and volume of eluting solvent, and pH were investigated and optimized. Under the optimum conditions, the calibration graph was linear over the range of 0.07-30.0 mu g L-1 with the limit of detection of 0.02 mu g L-1. The relative standard deviations (RSDs) at the 0.1 and 10.0 mu g L-1 levels of diazinon (n = 5) were 3.8 and 2.0 %, respectively. The proposed method was successfully applied to the determination of trace amount of diazinon in tomato, cucumber, apple, and well water samples.