Dummy molecularly imprinted microspheres prepared by Pickering emulsion polymerization for matrix solid-phase dispersion extraction of three azole fungicides from fish samples.

Dummy molecularly imprinted microspheres (DMIMs) were synthesized by Pickering emulsion polymerization and used as the matrix solid-phase dispersion extraction (MSPD) sorbent for sample pre-treatment of azole fungicides in fish samples. Alpha-(2,4-Dichlorophenyl)-1H-imidazole-1-ethanol (DCE) was used as the fragment dummy template for the imprinting of climbazole (CBZ), clotrimazole (CMZ) and miconazole (MNZ). The morphology of the microspheres were characterized by scanning electron microscopy (SEM) and nitrogen adsorption measurements, narrow diameter distribution (20-50 μm) with regular spherical shape and high surface area (SBET = 408.91 ± 6.72 m2 g-1) were achieved. Good class-selectivity of the DMIMs was found for CBZ, CMZ and MNZ by static adsorption experiments. The imprinted microspheres as MSPD sorbent was then evaluated for the extraction and purification of CBZ, CMZ and MNZ in fish samples. The extracted azole fungicides were detected by HPLC-DAD analysis at 225 nm. MSPD conditions including elution, mass ratio of sample/sorbent and washing were carefully evaluated. The optimized MSPD method have good recoveries (89.2-101.5%) and reproducibility (RSDs 1.6-4.8%, n = 5) for fish samples spiked at 0.5, 2.5 and 12.5 μg g-1. The limits of detection (LODs) were 0.045, 0.036 and 0.033 μg g-1 for CBZ, CMZ and MNZ, respectively. The results show that this method has a good application prospect for the pretreatment of azole fungicides in fish samples.