Preparation and characterization of chitosan‐siloxane magnetic nanoparticles for the extraction of pesticides from water and determination by HPLC

Novel chitosan‐siloxane functionalized magnetic nanoparticles including chitosan polydimethyl siloxane, chitosan octadecyl siloxane, and chitosan phenyl siloxane were prepared and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and Zeta potential measurements. The particles were prepared from Fe3O4 functionalized by siloxane derivatives followed by coating with chitosan through a crosslinking mechanism. Infrared spectroscopy was used to confirm the reaction and conjugation between the three layers of the crosslinking chitosan, siloxane and magnetic nanoparticles. The nanoparticles were applied as effective sorbents for extraction of seven pesticides (abamectin, diazinon, fenamiphos, imidacloprid, lambda‐cyhalothrin, methomyl and thiophanate‐methyl) from water. The particles were used in a magnetic dispersive solid‐phase extraction technique and solid‐phase extraction cartridge. The pesticides were then quantified by using high‐performance liquid chromatography with limit of detection of 0.002–0.046 μg/mL, limit of quantification of 0.006–0.154 μg/mL and excellent linearity in the range of 0.0125–0.15 μg/mL with correlation coefficients (R2) higher than 0.999. The magnetic nanoparticles showed a high recovery efficiency compared to standard octadecylsilane (Sigma–Aldrich) for some pesticides. The results indicated that these methods achieved the rapid and simple extraction of small quantities of adsorbents and solvent with a high recovery rate.