Study On Preparation Of Norfloxacin Molecularly Imprinted Polymers And Its Application In Solid Phase Extraction Technology

The molecularly imprinted polymers (MIPs) are obtained by copolymerization of functional monomer and cross-linker in the present of the template and after removal of the template the three-dimensional sites complementary to the template in shape and functionality are revealed. It can rebind the template and analogue specifically, so it is named'artificial antibody'. Solid phase extraction (SPE) used MIPs as the sorbent can overcome the defects that the common sorbent of SPE has low specificity. It can not only retain the trace template molecule specifically but also remove the other compounds present in sample matrix. So molecularly imprinted solid phase extraction (MISPE) provides a simple and effective pre-treatment method.In this research, MIPs were prepared by precipitation polymerization using norfloxacin, a kind of quinolone antibiotics, as the template. The conditions of polymerization, including functional monomer, cross-linnker and so on, were optimized and the MIP with the best specific adsorption capacity to norfloxacin was obtained. Then the characterization of the MIP was evaluated. At last the MIP was applied as the sorbent of SPE and the procedure of MISPE was optimized. The main contents of this research are described as follows:1. A series of norfloxacin molecularly imprinted polymers were prepared by precipitation polymerization. The compositions of polymers, including the porogenic solvent, the functional monomer, the cross-linker, were optimized by comparison of the imprinted factor. The MIP with the best affinity to the template was abtained. The compositions of the best-performing MIP were as follows: 0.32 g norfloxacin, 4 mmol MAA, 10 mmol EGDMA and 40 mg AIBN were dissolved in 60 mL methanol and the mixture was polymerized at 60℃for 24 h. In this condition, the imprinted factors of the prepared polymer to quinolone antibiotics (norfloxacin, ciprofloxacin, sarafloxacin, difloxacin) were 3.17, 3.29, 3.33, 2.84 respectively.2. The characterization of the best-performing polymer was examined by several different methods. The results of chromatographic evaluation indicated that the best-performing MIP can absorb the template specifically. The value of the total amount of the immobilized ligand was 12.08μmol/g by frontal chromatography. The polymer particles were regular examined by Scanning electron micrograph. At last, the hydrogen bond between MIP and the template was confirmed by infrared spectrum.3. The best-performing molecularly imprinted polymer was applied as the sorbent of SPE and the conditions of MISPE, including loading, washing and eluting, were optimized. The optimal MISPE protocol was loading with acetonitrile, washing with 3 mL acetonitrile/water (88/12, V/V) and eluting with 3 mL 5% acetic acid solution (in acetonitrile, V/V)/water (86/14, V/V). Under this protocol, when 4 mL 1.25 mg/L quinolone antibiotics solution (in acetonitrile) were loaded onto the MISPE cartridges, the recoveries of norfloxacin, ciprofloxacin, sarafloxacin, difloxacin were 96.92%, 97.49%, 56.75%, 0.00% respectively.