Highly selective stir bar coated with dummy molecularly imprinted polymers for trace analysis of bisphenol A in milk

A water compatible molecularly imprinted polymers (MIPs) coated stir bar for bisphenol A(BPA) was prepared with 3,3′,5,5′-tetrabromobisphenol A as the dummy template molecule in this study. The dummy molecularly imprinted polymers coated stir bar (DMIPs-SB) showed better selectivity than the bars coated with polydimethylsiloxane or non-imprinted polymers when used to extract BPA and its three analogues. The saturated adsorption amount of the DMIPs coating was 3.0 times over that of the non-imprinted polymers coating. To achieve the optimum extraction performance, several parameters, including extraction and desorption time, pH value, adsorption temperature and stirring speed were investigated. The high-performance liquid chromatography combined with the DMIPs-SB was employed in the analysis of BPA in aqueous solution. The linear range of BPA concentration in aqueous medium was 0.0228–2.28 ng/mL with correlation coefficient of 0.9994 and the detection limit was about 6.84 × 10−3 ng/mL based on three times ratio of signal to noise. This method was directly applied to the determination of trace BPA in milk with satisfactory results.