Synthesis of tetracycline-imprinted polymer microspheres by reversible addition-fragmentation chain-transfer precipitation polymerization using polyethylene glycol as a coporogen.

Tetracycline (TC)-imprinted microspheres have been synthesized by reversible addition-fragmentation chain-transfer precipitation polymerization using PEG as a coporogen. In the synthesis, methacrylic acid and ethylene dimethacrylate were used as the functional monomer and cross-linker, respectively. 2,2'-Azobisisobutyronitrile was the initiator, and cumyl dithiobenzoate was the chain-transfer reagent. Although monodispersed microspheres were obtained using acetonitrile as porogen, the particles cannot be used in the column extraction because of the high backpressure. To increase the porosity of the material, PEG was introduced as a coporogen. The influence of the molecular weight and concentration of PEG on the morphology, binding affinity, and porosity of the molecularly imprinted polymers (MIPs) have been studied. The results demonstrated that PEG as a macroporogen increased the porosity of the polymers. Meanwhile, the column backpressure was reduced using the MIPs with higher porosity. The binding affinity of the MIPs was increased when a low concentration of PEG was employed, while it was decreased when the ratio of PEG 12,000/monomers was >0.8%. Under the optimized conditions, TC-imprinted microspheres with good selectivity and size uniformity have been obtained, which facilitates its application in the column extraction for TC determinations.