Performance evaluation of functionalized chitosan-siloxane nano-sorbents for pesticides extraction and removal from aqueous samples

The present work describes novel chitosan-siloxane nano-sorbents (Ch-Si NS), including chitosan phenyl siloxane (Ch-PS NS), chitosan octa-decyl siloxane (Ch-ODS NS), and chitosan decyl siloxane (Ch-DS NS) for solid-phase extraction (SPE) and removal of seven pesticides from the water samples. Different chemical groups of pesticides, including abamectin, diazinon, fenamiphos, imidacloprid, lambda-cyhalothrin, methomyl, and thiophanate-methyl were examined in this study. The nano-sorbents were designed as core–shell particles based on the combination of silylation and cross-linking mechanism. The factorial design was used to optimize the retention variables (suitable elution system and sorbent amount). The chemical and morphological parameters of Ch-Si NS were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), X-ray diffraction, and Zeta Potential. The characterization results established the chemical structure and the conjugation between the nano-sphere layers (core–shell). SEM observed that the Ch-Si NS have a nano-spherical morphology, where the average size values were 206, 99, and 136 nm for Ch-PS NS, Ch-ODS NS, and Ch-DS NS, respectively. Moreover, the developed SPE cartridges provided good recognition and fast adsorption dynamics for the tested pesticides with good repeatability in the range of 0.21–8.86% and enrichment factor 2.91–8.81 µg/mL. Under the optimized conditions, the proposed SPE cartridges were successfully applied for pesticide extraction from water with high relative recoveries up to 99.54%. The validation parameters of the developed method provided a low limit of detection (0.02–0.46 µg/L) and limit of quantification (0.006–0.0154 µg/L).