Superparamagnetic core-shell dummy template molecularly imprinted polymer for magnetic solid-phase extraction of food additives prior to the determination by HPLC

Abstract

A highly sensitive and selective method for the simultaneous extraction and determination of trace vanillin, ethyl vanillin, maltol and ethyl maltol in beverage samples using magnetic solid-phase extraction coupled with high-performance liquid chromatography (HPLC) was developed. The novel superparamagnetic dummy template molecularly imprinted polymers (Fe3O4@MDMIP) were prepared by adopting a sol-gel approach using 3-hydroxy-2,6-bis(hydroxymethyl) -4-pyrone, whose structure was similar to that of the vanillin and maltol, as the dummy template for selective extraction of vanillin, ethyl vanillin, maltol and ethyl maltol. The obtained Fe3O4@MDMIP exhibits high uniformity and monodispersity. Besides, Fe3O4@MDMIP has an outstanding magnetic susceptibility (56.33 emu g−1) than common obtained samples. The maximal adsorption capacity (Qmax) of the resulting Fe3O4@MDMIP for the four food additives was up to 609.99 mg g−1. The imprinting factors of the Fe3O4@MDMIP ranged from 2.07 to 2.71 for the four food additives, which indicated that the obtained adsorbents have high selectivity. Under the optimum experimental conditions, the Fe3O4@MDMIP was successfully applied to the magnetic solid-phase extraction of vanillin, ethyl vanillin, maltol and ethyl maltol followed by HPLC determination in beverage samples. Validation experiments indicated that the developed method presented good linearity (2.07–463 ng mL−1), satisfactory precision (RSD, 2.68–6.91%), and high recovery (91.2–107.1%). The limits of detection ranged from 44 to 201 ng L−1, and the enrichment factors were in the range of 432–484. The results demonstrated great potential of the optimized method for sample preparation in routine analysis of trace food additives.