A novel, high-performance, recyclable heterogeneous catalyst functionalized with melamine was advantageously prepared and rhodanine on magnetic silica was successfully carried out. After that, the Cu ions were coordinated with the existing ligands decorated on the magnetic silica surface. This catalyst was identified by different analyses and acted as a recoverable catalyst for xanthene synthesis. Its advantages include the solvent-free conditions of the reaction, the high efficiency of the products in a short period of time, as well as its simple collection from the reaction environment. Moreover, the prepared sorbent has been developed for the extraction of diazinon from different real samples through magnetic solid phase extraction (MSPE). Under optimal conditions, the linear range for measuring diazinon was 0.5-200 µg L-1. The coefficient of determination (R2) was 0.9985. The limit of detection (LOD) of the method was 0.08 μg L-1. Relative standard deviation values (RSD%) for the concentration of 10.0 μg L-1 and 100 μg L-1 were between 5.3% and 5.9%. Finally, the proposed method was used to determine diazinon in orange and agricultural water. The results showed that the percentage of relative recovery of the selected toxin in the studied real samples was between 92 and 105. Moreover, the prepared sorbent has been developed for the extraction of diazinon from different real samples through magnetic solid phase extraction (MSPE). The parameters affecting the extraction were optimized by response surface methodology (RSM). The optimal extraction conditions were 15 min for contact time, 7 mg for sorbent amount, and 0% (w/v) for NaCl concentration. Moreover, 20 µL of methanol was used to elute the extracted analyte. Under optimal conditions, the linear range for measuring diazinon was 0.5-200 µg L-1. The coefficient of determination (R2) was 0.9985. The limit of detection (LOD) of the method was 0.08 μg L-1. Relative standard deviation values (RSD%) for the concentration of 10.0 μg L-1 and 100 μg L-1 were between 5.3% and 5.9%. Finally, the proposed method was used to determine diazinon in orange and agricultural water. The results showed that the percentage of relative recovery of the selected toxin in the studied real samples was between 92 and 105.
