Synthesis and Evaluation of a Magnetic Molecularly Imprinted Polymer Sorbent for Determination of Trace Trichlorfon Residue in Vegetables by Capillary Electrophoresis

摘要

In this study, a magnetic molecularly imprinted polymer (MMIP) based on Fe3O4@SiO2@CdTe (CdTe@MMIP) was synthesized using trichlorfon as template molecule, methacrylic acid (MAA) as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. The prepared MMIP was characterized, and the results showed that it exhibited good recognition and selective ability, offered a faster kinetics for the adsorption of trichlorfon. Scatchard analysis indicated that the binding sites in the CdTe@MMIP had two distinct groups (the high and low affinity binding sites). The saturated adsorption capacity (Q(max1)) was 63.2 mg/g due to the low affinity binding sites, and another saturated adsorption capacity (Q(max2)) was 71.4 mg/g due to the high affinity binding sites. Using it as sorbent, a method of molecularly imprinted magnetic solid-phase extraction coupled with capillary electrophoresis (MIMSPE-CE) for selective extraction, magnetic separation, and fast determination of trace trichlorfon in vegetable samples was developed. Under optimal conditions, appreciable sensitivity was achieved with a LOD of 30 g/kg (S/N = 3) for the developed method. The relative standard deviation (RSD) for five replicate extractions of 0.05 mg/L trichlorfon standard solution was 4.2%. To evaluate the accuracy of this method, the blank cucumber and cauliflower samples spiked with trichlorfon were extracted and analyzed by this method with good recoveries ranging from 78.7% to 96.6%. Moreover, this method was applied to the quantitative detection of the trichlorfon residues in rape samples, and the results correlated well with that obtained from the gas chromatography method.