Preparation and evaluation of superparamagnetic surface molecularly imprinted polymer nanoparticles for selective extraction of bisphenol A in packed food

Molecularly imprinted polymer (MIP) coated Fe3O4 nanoparticles (Fe3O4@MIP) were synthesized by atom transfer radical polymerization (ATRP) and used as highly selective magnetic solid-phase extraction (MSPE) sorbents for trace bisphenol A (BPA) from packed food. The morphological and polymeric characteristics of the Fe3O4@MIP were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. In this work, competitive recognition compounds (4-n-octylphenol and bisphenol A diglycidyl ether) exhibited lower binding capability to the Fe3O4@MIP than BPA. A high performance liquid chromatography with fluorescence detection (HPLC-FLD) method was developed for the determination of BPA in canned orange and milk samples. The main factors influencing the extraction efficiency, including high specificity, the amount of surfactant, the shaking time and the desorption ability of complex food matrices were investigated and optimized. Various parameters such as the pH of the sample, the amount of Fe3O4@MIP sorbent, the extraction time, and the desorption conditions were optimized. Notably, the extraction can be carried out quickly, and the extraction time for BPA onto Fe3O4@MIP sorbents can be clearly shortened to 5 min. Good linearities (r(2) > 0.9965) for all calibration curves were obtained, and the limit of detection (LOD) for BPA was 0.1 and 0.3 ng mL(-1) in canned orange and milk samples, respectively. To the best of our knowledge, this is the first time that surface molecularly imprinted polymer nanoparticles have been used for the pretreatment of packed food.