3rd TAGRA

Organophosphorus pesticides are extensively used in agricultural applications, and their residues in aquatic environments have raised significant environmental and analytical concerns. In this study, a solid-phase extraction method based on functionalized single-walled carbon nanotubes (SWCNTs) was developed for the extraction and preconcentration of diazinon and malathion from aqueous samples prior to gas chromatography–mass spectrometry (GC–MS) determination. Carboxylated SWCNTs were functionalized with different organic modifiers, including diphenylmethanol, benzyl alcohol, and cyclohexanol, and their extraction performances were comparatively evaluated. Among the investigated sorbents, diphenylmethanol-functionalized carbon nanotubes exhibited the highest extraction efficiency and were therefore selected for further optimization. The effects of several experimental parameters, including desorption solvent, extraction and desorption times, sorbent amount, sample pH, extraction and desorption temperatures, and solvent volumes, were systematically investigated. Acetonitrile showed the highest desorption efficiency for both analytes and was selected as the optimum desorption solvent. A sample pH of 7 was selected for subsequent experiments to achieve efficient extraction while minimizing possible pesticide degradation. The extracted analytes were determined by GC–MS using selected ion monitoring (SIM). Characteristic ions at m/z 125, 173, and 93 were monitored for diazinon, whereas m/z 179, 152, and 137 were used for malathion. The results demonstrated that surface functionalization of carbon nanotubes, particularly with diphenylmethanol, enhanced their extraction performance toward the investigated organophosphorus pesticides. The developed approach provides a simple and effective strategy for the extraction and preconcentration of diazinon and malathion from aqueous samples and demonstrates the potential application of functionalized carbon nanotubes as sorbents for trace pesticide analysis.