In situ self-assembled coating of surfactant-mixed metal hydroxide on Fe3O4@SiO2 magnetic composite for dispersive solid phase microextraction prior to HPLC analysis of triazole fungicides

A new approach for the determination of five triazole fungicides, i.e. triadimefon, flusilazole, tebuconazole, penconazole and propiconazole, in water samples has been developed. The developed method was based on a self-assembled coating of surfactant-mixed metal hydroxide on Fe3O4@SiO2 magnetic composite. The resulting coated nanocomposite was directly used as an efficient sorbent in dispersive solid phase microextraction of the triazole fungicides. As an in-situ process, surface modification of the sorbent and extraction of the triazole fungicides were accomplished together. Also, the combined unique properties of the composite sorbent exhibited superior performance in terms of high separation and extraction efficiency. After the studied extraction, the extracted triazole fungicides were separated and quantified using high performance liquid chromatographic analysis. The parameters for the optimum extraction condition were 100 mL sample volume, 20 mg of Fe3O4@SiO2 sorbent, 10 mg of sodium dodecyl sulfate, 0.738 g of Mg(NO3)2, 0.36 g of Al(NO3)3, 1 g of NaCl, pH 10, 10 min of extraction time and 6 mL of acetonitrile as desorption solvent. Under the optimized condition, the linearity was obtained in the range of 5–100 µg L−1 for triadimefon and 2.5–50 µg L−1 for flusilazole, tebuconazole, penconazole and propiconazole. The obtained limits of detection were 1.0–2.5 μg L−1. High precision (the intra–day and inter–day precision) was achieved with the relative standard deviation of less than 8%. The enhancement factors ranged from 40 to 237. The proposed extraction was successfully applied for the analysis of the triazole fungicides in water samples with good recovery in the range of 90–104%.