Detection of avermectin pesticide residues in pine trees based on magnetic Solid-Phase extraction combined technology

To improve the detection accuracy and efficiency of avermectin pesticide residues in pine trees, this study develops an analysis method based on MSPE combined with high-performance liquid chromatography tandem mass spectrometry. A core-shell magnetic nanomaterial, Fe₃O₄-SiO₂-NH₂-Schiff-TAPB-DA, is synthesized by the solvothermal method. The Fourier Transform Infrared Spectroscopy (FTIR) analysis results confirmed its stable characteristic functional group structure (such as benzene ring, amide bond) and significant magnetic separation performance. Efficient adsorption of avermectin was achieved by utilizing the abundant benzene ring and amide bond sites on the material surface, and the solid-phase extraction pretreatment conditions were optimized. The results demonstrated that the target substance exhibited good linearity under optimal extraction conditions (R² > 0.998). The matrix effects of standardized avermectin pesticides were all greater than 92%, and the Limit of Detection (LOD) for methomyl, avermectin, and tetracycline were 0.213, 0.185, and 0.209 mg L^-1. The average recovery rate of some target substances was 73.2-85.6%. This study presents an efficient and environmentally friendly technical solution for the precise monitoring of avermectin residues in the prevention and control of pine wilt disease, providing a methodological reference for the multi-residue analysis of other forestry pesticides.