Magnetic nanoparticles modified with hyperbranched polyamidoamine for the extraction of benzoylurea insecticides prior to their quantitation by HPLC

A magnetic sorbent was fabricated by covalently grafting hyperbranched polyamidoamine onto the surface of Fe₃O₄ nanoparticles. The sorbent was used in the magnetic solid-phase extraction (MSPE) of benzoylurea insecticides (BUs) from environmental water samples. It is perceived that hydrogen bonding interactions and hydrophobic interactions are the main mechanisms for the adsorption of BUs. The sorbent was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, elemental analysis, Brunauer-Emmett-Teller measurement, X-ray photoelectron spectroscopy, vibrating sample magnetometry and X-ray diffraction. Various experimental parameters affecting the MSPE were optimized. Following elution with acetonitrile, the BUs were quantified by HPLC with diode array detection. The method based has a wide linear response range (2.5–500.0 ng mL⁻¹), satisfactory coefficient of determination (0.9922–0.9976), high enrichment factors (62.8–74.4), acceptable limits of quantitation (2.5 ng mL⁻¹) and low limits of detection (0.39–0.72 ng mL⁻¹). The intra-day precision at concentration levels of 5.0, 50.0 and 250.0 ng mL⁻¹ ranged from 2.3–6.4% and the inter-day precision was between 1.0 and 5.5%. The sorbent can be re-used at least 15 times. It was applied to the extraction of BUs from genuine water samples where it showed satisfactory relative recoveries (75.1–111.4%) and precision (1.0–9.1%).

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