Preparation And Adsorption Performance Of Molecularly Imprinted Polymer For Sulfonamides Antibiotics

Sulfonamides（SAs） as pharmaceuticals and personal care products（PPCPs） are the emerging contaminants closely linked with people’s daily life. The concentrations in the environment and the environment behavior of them have got more and more attention. However many problems such as complicated existence form, low content, various interference lead to many errors in the test procedure. So the studies of pretreatment and detection technology for SAs in the environmental water samples are significant in academic and application. Molecularly imprinted polymer（MIP） synthesized by molecularly imprinted technique（MIT） has strong adsorption ability, high selectivity, good stability and reusability, which provides a new approach for the environmental monitoring and governance. In this study, the MIP with group selectivity was synthesized by the different preparation methods and used as solid phase extraction adsorbent and chromatographic stationary phase, respecitvely. Meanwhile, three deteciton methods, molecularly imprinted solid phase extraction coupled w ith HPLC（MI-SPE-HPLC）, molecularly imprinted dispersion solid phase extraction coupled with HPLC（MI-DSPE-HPLC） and molecularly imprinted capillary electrochroma-tography（MI-CEC）, have been developed for determination of trace SAs in different environmental water samples.Firstly, to get MIP with the specific recognition and the high affinity for analogues, the bulk polymerization method was used to synthesize the group selective polymer based on the mixed templates theory. By optimizing preparation conditions, sulfamerazine and sulfamethoxazole were used as mixed template, 2-vinylpridine as functional monomer and ethylene dimethacrylate as cross-linker respectively. Moreover the molar ratio was 1:1:6:20. Meanwhile the porous structures and the adsorptive property of MIP were studied by BET analysis and adsorption experiments. The results showed that the porous property of mixed template MIP was beneficial to the adsorption and medium transmitting of target analytes. The maximum adsorbing capacities of MIP for mixed template were Qmax（SMX）=20.97 mg/g,Qmax（SMR）=19.74 mg/g. The adsorption equilibrium time was 2.5 h. The static isothermal adsorption and the dynamic adsorption of mixed template MIP fitted to Freundlich model and pseudo second-order kinetic model, respectively. The MIP showed strong affinity and excellent selectivity for template and its analogues. The imprinted factor was in the range of 3.30 to 4.49. Furthermore the molecularly imprinted action mechanism was investigated by UV and the results showed that the mixed template could form host-guest coordination compound with functional monomer through noncovalent interaction. The ratios were 1:2 and 1:2-1:3. These results implied that the introduction of mixed template could enhance the heterogeneity and increase the recognized ability of MIP, which was beneficial for the adsorption of SAs.Secondly, for the problems of complicated matrix, low selective adsorbents, large volumn of sample and time-consuming extraction in the pre-treatment of environmental samples, magnetic MIP sorbents were synthesized by surface imprinting method. The core-shell magnetic molecularly imprinted polymer（Fe₃O₄/CS@MIP） was prepared using Fe₃O₄/CS as core, sulfamerazine and sulfamethoxazole as mixed template, 2-vinylpridine as functional monomer and trimethylolpropane trimeth-acrylate as corsslinker through optimizing preparation conditions. Fe₃O₄/CS@MIP was characterized by FT-IR, XRD, SEM, TEM, TGA and VSM, and the adsorption ability of Fe₃O₄/CS@MIP was evaluated. The results showed that MIP coating w as co-polymerized on the surface of Fe₃O₄/CS and grafting efficiency was 74.4%. The cubic crystal structure of Fe₃O₄ was no change and the good magnetic induction of Fe₃O₄/CS@MIP was reflected. The maximum adsorbing capacit ies of Fe₃O₄/CS@MIP for mixed template were Qmax（SMX）=16.21 mg/g, Qmax（SMR）=15.49 mg/g. The adsorption equilibrium time was 9 min. The adsorption experiment s demonstrated that the isothermal adsorption and the dynamic adsorption of Fe₃O₄/CS@MIP fitted to Freundlich model and pseudo second-order kinetic model. Fe₃O₄/CS@MIP showed high affinity and group selectivity for SAs（IF=3.44-4.30）.Thirdly, to establish efficient, rapid and high selective CEC method, the MIP monolith was prepared by in-situ polymerization. The synthetic conditions were optimized. The optimal ratio of template molecular, functional monomer an d crosslinker was set 1:4:10. Methylbenzene and dodecanol were selected as porogen agent and accounted for 12% of the total mass. The temperature and time of reaction were 45 ℃ and 7 h respectively. Meanwhile the structure of MIP monolith was characterized and the separated conditions were optimized. The results showed that the MIP monolith has stable performance, strong remained capacity for template, and good permeability. The optimum chromatographic separation conditions were 15 mmol/L of sodium acetate（p H=5.0）, 75% of acetonitrile content, 15 k V of separation voltage, 20 ℃ of column temperature. The resolution was 1.67 of sulfamerazine and sulfamethazine. Seven SAs were separated in 12 min on MIP monolith using the optimized conditions. The good retained ability and high column efficiency of MIP monolith was embodied.Based on the above study, three analytical methods for the detection of trace SAs in water were established. The enrichment conditions of MI-SPE and MI-DSPE were optimized, which obtained a set of best parameters: 500 m L of sample volume, 3-7 of p H value, and 8 m L 1% formic acid-menthol of elution solvent in MI-SPE; 100 mg of adsorbent dosage and 6 m L 0.5% formic acid-menthol of elution solvent in MI-DSPE. The environmental water samples were analyzed from WWTP influent effluent and fish pond water in A city, WWTP influent and efflue nt in B city.The results showed that the recoveries and relative deciations, of MI-SPE-HPLC were 85.39-100.98% and lower 10.89% respectively. The recoveries and relative deciations of MI-DSPE-HPLC were 86.91-99.09% and lower 11.99% respectively. The enrichment factor and method detection limit were 436.10-490.80 and 8.09-18.32 ng/L. The recoveries, relative deciations and instrument detection limit of MI-SPE-CEC were 83.09-97.98%, lower 7.76% and 40.02-76.12 ng/m L respectively. Three analyzed methods could satisfy the confirmation of trace SAs in environmental water and the request of multi-trace analysis.