| Monolithic column microextraction(PMME)has been widely used because of its simple preparation process,easy modification,wide p H range,less solvent consumption and so on.By mixing specific solutions of monomer,crosslinking agent,pore-forming agent and initiator,organic polymer monolithic column can be easily synthesized by thermal initiation or photo-initiated free radical polymerization.The pore size and surface area of monolithic column can be controlled by the type and composition of pore-forming solvent and the percentage of crosslinking agent.At present,the types of polymer monolithic column materials are limited,which still can’t meet the requirements of separation and enrichment of trace targets in samples with different properties.To prepare a new type of polymer monolithic column with excellent adsorption efficiency provides new extraction materials for enrichment and concentration of targets in environment and food,and also provides a new idea for the development of solid media for sample pretreatment.In this paper,the preparation of bifunctional monomer polymer monolithic column is carried out,which can be used as a sample pretreatment method in food and environment to further realize the extraction and enrichment of trace target.The specific research contents are as follows:1.With methacrylic acid(MAA)and N-vinylcarbazole(NVC)as bifunctional monomers,a poly(MAA-EDMA-NVC)monolithic column was prepared by thermally initiated polymerization.The properties of the column were characterized by scanning electron microscope(SEM),fourier transform infrared spectroscopy(FT-IR)and X-ray photoelectron spectroscopy(XPS).The effects of p H value,sample volume,ionic strength and elution flow rate on the extraction performance of 0.1μg/m L rhodamine B were investigated by the monolithic column.Under the optimum experimental conditions,the linear range of this method is 5-350μg/L,the linear equation is A=0.0029 C-0.0826,R~2=0.9992,the detection limit(S/N=3)is 3.49μg/L,the limit of quantification(S/N=10)is 11.64μg/L,and the relative standard deviation is 1.10%(n=11).The pre-enrichment coefficient is 14.5.The method has the advantages of low cost,wide linear range and low detection limit,and is used for the analysis and detection of rhodamine B in wine,with the recovery rate of 90.1-99.2%.2.With methacrylic acid(MAA)and 4-vinylphenylboronic acid(VPBA)as bifunctional monomers,a poly(MAA-EDMA-VPBA)monolithic column was prepared.The column was porous and uniform in structure,and catechol could be enriched and extracted by borate affinity,conjugation and hydrogen bonding.By optimizing the p H value of elution solvent,loading volume,ionic strength and elution flow rate,an analytical method for the determination of catechol by poly(MAA-EDMA-VPBA)monolithic column combined with ultra-high performance liquid chromatography(UPLC)was established.Under the best experimental conditions,this method has a good linear relationship in the range of 0.10-0.60μg/m L,and the correlation coefficient is 0.9988.The detection limit of this method is 0.11μg/m L,the quantitative limit is 0.38μg/m L,the enrichment factor is 8.2,and the extraction rate is 82.3%.The method has been applied to the determination of catechol in tap water and drinking water,and the recovery rate is 97.1-106%,with satisfactory experimental results.3.Poly(VBA-DVB-VPBA)monolithic column was prepared by copolymerization of 4-vinylbenzoic acid(VBA)and 4-vinylphenylboronic acid(VPBA)with divinylbenzene(DVB),which was used to extract sulfonamides from honey.The column is rich in functional groups,uniform and porous,and has good permeability and stability,which can produce various forms of interaction with sulfonamides.By optimizing the extraction conditions,the analytical method of polymer monolithic column microextraction combined with ultra-high performance liquid chromatography(PMME/UPLC)was established,and sulfadiazine,sulfamethazine,sulfapyridine and sulfathiazole in actual samples were extracted and separated.Under the optimal experimental conditions,the linear relationship of the four target substances in the corresponding mass concentration range is good,and the correlation coefficients(r~2)are all greater than 0.99.The detection limit of this analytical method is 8.32-16.2 ng/m L,the quantitative limit is 27.5-53.9 ng/m L,and the recovery rate of actual samples is 89.8-105%.This method is characterized by less reagent consumption,short time consumption and simple operation. |
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