Monitoring of ractopamine concentration in the mixture of this feed additive with vitamin mineral complex and with swine feed by HPLC.
In this study, a molecularly imprinted functionalized polymer for the selective separation of ractopamine (RAC) was prepared by combining a surface molecular imprinting technique with a sol-gel method process. The polymer was evaluated by static, kinetic adsorption, and selective experiments. Results indicated that the molecularly imprinted polymer had high adsorption capacity, selective ability, and fast mass transfer rate. The polymer was applied for the determination of trace RAC through online SPE-HPLC. With a sample loading flow rate of 2 mL/min, the enhancement factor of 516.26 and the LOD (S/N = 3) of 4.6 ng/L were achieved, respectively, and the linear range of the calibration curve was 0.04-18 microg/L with r(2) >0.99. The RAC in pork was determined at three spiked levels (0.5, 1, and 2 ng/g) with recoveries ranging from 55.86 to 67.28%.