Magnetic adsorbent based on mesoporous silica nanoparticles for magnetic solid phase extraction of pyrethroid pesticides in water samples.

Mesoporous KIT-6-magnetite composite (Fe3O4@SiO2@KIT-6) was successfully prepared and characterized by transmission electron microscopy, scan electron microscopy, elemental mapping, energy dispersive X-ray spectrum, Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray powder diffraction, Brunauer Emmett Teller analysis and magnetic property analysis. It was then applied as adsorbent for magnetic solid phase extraction of fenpropathrin, lambda-cyhalothrin, S-fenvalerate and bifenthrin from water samples before analyzed by high performance liquid chromatography-ultraviolet detector. A few factors impacting extraction were studied. The optimal results were acquired by using acetonitrile to eluent the targets adsorbed on 40 mg of Fe3O4@SiO2@KIT-6 adsorbent in 100 mL water samples at a pH of 7 at 25 ℃ within 10 min. The experimental limit of detections of fenpropathrin, cyhalothrin, S-fenvalerate and bifenthrin are 0.01 × 10-3, 0.006 × 10-3, 0.01 × 10-3 and 0.005 × 10-3 mg∙L-1, respectively. Good relative recoveries (86.58-98.80%) and reproducibility values are also obtained. The kinetic experiment shows that the adsorption follows pseudo-second order, while the isotherm experiment follows Langmuir isotherm model. Trace pyrethroid pesticides in water samples can be detected by the developed magnetic solid phase extraction technique followed by high performance liquid chromatography, which is simple, easy, environmental friendly and efficient.