Preparation of bifunctional magnetic nanoparticles with octadecyl and phosphate groups by thiol–ene click chemistry for extraction and enrichment of organophosphorus pesticides in tea drinks

Abstract

Bifunctional magnetic nanoparticles with octadecyl and phosphate groups were synthesized by thiol–ene click chemistry and applied for pre-concentration and extraction of organophosphorus pesticides (OPPs). Vinyl phosphonic acid functionalized MNPs (Fe₃O₄@VPA) behaved as clickable sites and reacted with octadecanethiol (C₁₈-SH) by a thiol–ene click reaction. The resultant material (Fe₃O₄@VPA@C₁₈) was characterized by scanning electron microscopy, FTIR, transmission electron microscopy and magnetic measurements. The results revealed that the particles exhibited spherical morphology and excellent magnetic response signals. The extraction efficiency was studied using four OPPs as test analytes from tea drink samples and their determination using high performance liquid chromatography was evaluated. Various extraction conditions were investigated in detail. Under optimal conditions, using the recommended method the linear range for the analytes was 0.1–300 μg L⁻¹, the detection limits ranged from 0.01–0.05 μg L⁻¹, and the enrichment factors ranged from 420 to 455. This method was then successfully used to determine OPPs from tea drink samples with desirable recovery ranging from 81.7 to 92.8%. Meanwhile, based on the hydrophobicity of the C₁₈ groups and the selectivity of the phosphate groups, the extraction efficiency of Fe₃O₄@VPA@C₁₈ for OPPs was superior to that of the commercial adsorbent (Fe₃O₄@SiO₂@C₁₈).