Synthesis of a monodisperse well-defined core–shell magnetic molecularly-imprinted polymer prior to LC-MS/MS for fast and sensitive determination of mycotoxin residues in rice

In this paper, a monodisperse, well-defined core–shell magnetic molecularly-imprinted polymer (MD-CS-MMIP) was controllably synthesized via modified precipitation polymerization and used as a magnetic solid-phase extraction adsorbent for the simultaneous determination of six trace mycotoxins in rice samples. The as-prepared MD-CS-MMIP was fully characterized by SEM, TEM, XRD, and TG-DTG. This study is particularly concerned with the influence of the amount of oleic acid used for MD-CS-MMIP synthesis on the material morphology, components, and adsorption efficiency. The results reveal that the modification of oleic acid on the Fe3O4 surface could improve the monodispersion of core–shell MD-CS-MMIP. Moreover, MD-CS-MMIP was used as a magnetic solid-phase extraction adsorbent for the determination of six mycotoxin residues in rice samples, and the adsorption and desorption conditions of MD-CS-MMIP toward mycotoxins were optimized to obtain the highest adsorption capacity, selectivity, and desorption efficiency. Under optimal conditions, the limits of quantitation (LOQs) of the developed method toward the six mycotoxins range from 0.003 μg kg−1 to 0.01 μg kg−1. The developed method was successfully used for the determination of mycotoxins in rice samples, with recoveries in the range of 86.3 to 103.1%.