Fabrication and using of Novel Molecularly Imprinted Polymer Nanotube Membranes of Ractopamine

Abstract: In this paper, methacrylic acid (MAA) was selected as functional monomer and the polymerization rate of ractopamine and MAA was 1:6. A method for the synthesis of ractopamine molecularly imprinted polymer (MIP) nanotube membranes using an anodic alumina oxide (AAO) template by surface-initiated atom transfer radical polymerization (ATRP) was presented. The morphology of MIP nanotube membranes were characterized by scanning electron microscope (SEM). The SEM results showed that ATRP route works well in the formation of MIP nanotubes within AAO template. A series of adsorption experiments revealed that the MIP nanotube membranes showed better extraction capacity and good selectivity than that of non- imprinted polymer (NIP) nanotube membranes for ractopamine and its analogues. In order to evaluate the usability of the MIP nanotube membranes, a methodology by combining MIP nanotube membranes extraction couple with high performance liquid chromatography (HPLC) detection for the determinationof β-agonists in complex samples was developed. The linear ranges were 10–1000 μg/L for ractopamine, 100–1000 μg/L for clenbuterol, epinephrine and dopamine, and 200–1000 μg/L for terbutaline. The detection limits were within the range of 0.074–0.25 μg/L and the RSDs (n=3) were from 2.79% to 4.34%. The method was successfully applied to the analysis of β-agonists in spiked pork samples, The recoveries of all the β-agonists at the two concentration levels were found to be the range of 86.32%-96.95% and 87.84%-95.73%, respectively. The RSDs were within 2.67-5.72 %. The results demonstrated that the proposed method is very suitable for the determination of trace β-agonists in pork samples.