A simple and fast method for magnetic solid phase extraction of ochratoxin A

Abstract

We report on the synthesis of dopamine loaded magnetic nanoparticles (MNPs) for new, simple, fast and repeatable extraction of ochratoxin A from different solvents and milk without utilizing immunoaffinity columns and even high-tech devices. To this end, Fe3O4 nanoparticles (NPs) were synthesized using thermal decomposition reaction and dopamine (DPA) was then conjugated with Fe3O4 nanoparticles (NPs) to form Fe3O4-DPA NPs. Dynamic light scattering, field emission scanning electron microscopy and transmission electron microscopy revealed an average size of about 15 nm for Fe3O4-DPA NPs. Moreover, zeta potential measurement and vibrating sample magnetometer confirmed positively charged (16.8 mV) and superparamagnetic behavior of MNPs, which are effective factors for a good adsorbent in the extraction. Various solvents and different effective parameters were measured until acetonitrile:methanol was selected as the best extraction solvent. In addition, based on the pH-partition theory, with changes in pH, we were able to increase and enhance the extraction rate to 94%. Moreover, the ability of Fe3O4-DPA NPs in solid phase extraction of ochratoxin A from spiked milk was evaluated. The recovery rate for extraction of OTA from milk was 68%.