Magnetite-sporopollenin/graphene oxide as new preconcentration adsorbent for removal of polar organophosphorus pesticides in vegetables

In this study, a new magnetic adsorbent based on magnetite-sporopollenin/graphene oxide (Fe₃O₄-SP/GO) was successfully developed. The adsorbent was applied for magnetic solid phase extraction (MSPE) of three selected polar organophosphorus pesticides (OPPs), namely, dimethoate, phenthoate, and phosphamidon, prior to gas chromatography analysis with electron capture detection (GC-μECD). The Fe₃O₄-SP/GO adsorbent combines the advantages of superior adsorption capability of the modified sporopollenin (SP) with graphene oxide (GO) and magnetite (Fe₃O₄) for easy isolation from sample solution. Several MSPE parameters were optimized. Under optimized conditions, excellent linearity (R² ≥ 0.9994) was achieved using matrix match calibration in the range of 0.1 to 500 ng mL⁻¹. The limit of detection (LOD) method (S/N = 3) was from 0.02 to 0.05 ng mL⁻¹. The developed Fe₃O₄-SP/GO MSPE method was successfully applied for the determination of these three polar OPPs in cucumber, long beans, bell pepper, and tomato samples. Good recoveries (81.0–120.0%) and good relative standard deviation (RSD) (1.4–7.8%, n = 3) were obtained for the spiked OPPs (1 ng mL⁻¹) from real samples. This study is beneficial for adsorptive removal of toxic pesticide compounds from vegetable samples.