Magnetic solid phase extraction sorbents using methyl-parathion and quinalphos dual-template imprinted polymers coupled with GC-MS for class-selective extraction of twelve organophosphorus pesticides.

Abstract

A novel magnetic dual-template molecularly imprinted polymer (DMIP) was prepared with methyl-parathion and quinalphos as templates. Forcomparison, a series of single-template polymers with only methyl-parathion (MPMIP) or quinalphos (QPMIP) as templateas well asanon-imprinted polymer (NIP) in the absence of the template, were synthesized usingthe same procedure of DMIP. The obtained MIPs were characterized by scanning electron microscopy(SEM), Fourier transform infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM), and X-ray diffraction (XRD). The properties including kinetic effect, thermodynamic effect, selectivity, and reusability of MIPs were investigated. Only DMIP possessed high affinity and good recognition for all twelve OPPs including quinalphos, isazophos, chlorpyrifos-methyl, chlorpyrifos, methidathion, triazophos, profenofos, fenthion, fenitrothion, methyl-parathion, parathion, and paraoxon in comparison toMPMIP, QPMIP, or NIP. Moreover, DMIP was used as magnetic solid phase extraction (MSPE) sorbent for the pre-concentration of twelve OPPs in cabbage samples. The developed DMIP-MSPE-GC-MS method showed high sensitivity, low LODs (1.62-13.9ng/g), fast adsorption equilibrium (10min), and acceptable spiked recoveries (81.5-113.4%) with relative standard deviations (RSD) in the range 0.05-7.0% (n= 3). The calibration plots were linear in the range 10-800ng/mL with coefficients of determination (R2) better0.99 for all twelve compounds. These results suggest that the DMIP is applicable for rapid determination and high throughput analysis of multi-pesticide residues. Graphical abstract.