Magnetically solid-phase extraction of diazinon and chlorpyrifos pesticides in vegetables using covalent triazine-based framework incorporated chitosan nanocomposite

A novel green magnetic chitosan-covalent triazine framework nanocomposite synthesized by incorporating Schiff base network-1 nanoparticles into the chitosan matrix. The magnetic nanocomposite was characterized using Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy-energy dispersive spectroscopy, X-ray diffraction, and vibrating-sample magnetometry. Then, the magnetic nanocomposite was used for the extraction and preconcentration of diazinon and chlorpyrifos pesticides from vegetable samples. The complex matrix of the vegetables was purified and simplified using the QuEChERS method before the magnetic solid phase extraction. Several parameters affecting the extraction efficiency of the pesticides, such as pH, amount of sorbent, adsorption time, agitation type and time of desorption, type and volume of eluent solvent, and sample volume were studied and optimized. Separation and determination of the pesticides were done by gas chromatographic instruments coupled with a flame ionization detector and a mass detector for the optimization and validation parameters, respectively. Under optimum conditions, analytical parameters of the method, including limits of detection (0.01 and 0.02 mu g L-1 ), linear ranges (0.04-500 and 0.07-500 mu g L-1), relative standard deviations (2.3 and 4.7), and enrichment factors (65 and 283) were obtained for diazinon and chlorpyrifos, respectively. The relative recoveries in zucchini, cucumber, and celery samples confirm the efficiency of the present method for determining organophosphorus pesticides in vegetable samples.

Automated summary

A novel green magnetic chitosan-covalent triazine framework nanocomposite was synthesized and characterized. It was used for the extraction and preconcentration of diazinon and chlorpyrifos pesticides from vegetable samples. The method showed good analytical performance and efficiency for determining organophosphorus pesticides in vegetable samples.