Investigation On Gas Phase Recognition Of Molecularly Imprinted Polymer By Inverse Gas Chromatography

In present work,toluene,furoic acid,paeonol and myrtenal were utilized as template molecules to prepare molecularly imprinted polymers by different preparation methods and their structure was characterized.The retention and adsorption behavior for these polymers towards template vapor were studied by inverse gas chromatography technology.The retention capability and selectivity of molecular imprinted column towards template molecules and their analogues was studied,respectively.And the rebinding capacity and adsorption isotherm of the target molecules on the imprinted column was measured.In addition,the adsorption capacity of the molecularly imprinted polymer towards the target molecules in the analytical sample was examined.All of work are abstracted as follows.(1)A homogeneous toluene-imprinted microsphere(MIP)was prepared by precipitation polymerization technique using toluene as porogen(also as the template)with 4-vinyl pyridine(4-VP)as the functional monomer.Structural characterization was performed by nitrogen adsorption method and optical microscope.Retention capability and selectivity for this MIP toward template vapor and its relative compounds were evaluated and the isotherm rebinding capacity of the MIP and its control polymer(CP).tested by adopting an inverse gas chromatography method.Results indicated that the toluene imprinted polymer(MIP3)stationary phase possessed high retention and selectivity toward gaseous template molecule under the optimized chromatographic conditions,with a retention factor value of 68.42,an imprinting factor of 7.049,and selectivity factor values of 4.821 and 5.370 for the template relative to toluene and p-xylene,respectively.A model mixture containing toluene,benzene and p-xylene could be effectively separated,resulting in a resolution of 5.138 for toluene to p-xylene and of 1.762 for toluene to benzene.The isotherm adsorption curve for the MIP3 toward toluene appeared the Ⅱ type of shape.Additionally,the toluene-imprinted microspheres had satisfactory effect in removing toluene,benzene and p-xylene from the polluted indoor air.(2)A furoic acid imprinted polymer was prepared by using furoic acid as template molecule and its structural characteristics were determined by infrared spectroscopy and scanning electron microscopy.When the polymer was used as the stationary phase in the gas chromatography,the performance of the retention and selectivity ofimprinted column was studied by inverse gas chromatography method.Also,the rebinding capacity of the target molecule and the structural analog on the imprinted column was tested and the adsorption capacity of imprinted polymer towards furoic acid explored.Results showed that MIP3 possessed the strongest retention ability on the target molecule and when the column temperature was 443 K,the selectivity factor values of the imprinted column for furoic acid relative to furfural was 11.55,indicating a high selectivity.Under the determined chromatographic conditions,the MIP3 column can effectively separate the model mixture containing furoic acid and furfural,with a resolution of 1.544 for furoic acid to furfural.By testing isotherm adsorption,it was showed that the adsorption capacity of MIP3 to furoic acid was much higher than of furfural.In addition,this imprinted material was also shown with a strong adsorption capacity towards furoic acid in the model solution.(3)A paeonol molecular imprinted polymer was prepared by using paeonol as template molecule,its structural characterization was performed by SEM and FTIR analysis.The specific recognition capacity for MIP towards target molecules was investigated and the selectivity and separation ability of target molecules and analogues on the MIP explored.Also,the rebinding capacity for this polymer,as a stationary phase in gas chromatography,toward gaseous molecules was tested.The adsorption isotherms of paeonol and its relative compound on the molecular imprinted column were obtained according to the retention values of analytes under different injection volume.The results indicated that the imprinted column possessed high selectivity and retention capacity toward gaseous template molecule under the optimized chromatographic conditions,with a retention factor value of 144.2 and a selectivity factor value of 6.61 for the paeonol relative to eugenol.In addition,the mixture of paeonol and eugenol can achieve complete separation on the molecular imprinting column.The adsorption isotherms of paeonol and eugenol on molecularly imprinted polymers showed that the target molecule had a strong binding interaction on the imprinting sites,and under the same conditions,the adsorption amount of paeonol is much higher than that of eugenol.These results indicated that paeonol imprinted material exhibited super selectivity and adsorption performance toward paeonol.(4)By using myrtenal as the template molecule and nano TiO2 as a carrier,a surface molecular imprinting technique was used to prepare the myrtenal imprinted material.Their structures were characterized by scanning electron microscopy and infrared spectroscopy,indicating that the molecularly imprinted polymer had beensuccessfully grafted onto the surface of the modified TiO2 matrix.The imprinted polymer prepared was used as the stationary phase in gas chromatography to test its retention properties toward gaseous analytes.The retention factor and the selectivity of the imprinted material toward the target molecule were also tested.The retention factor of the imprinted column on myrtenal was 63.4,a value much higher than that of the terpineol under the same chromatographic conditions.The rebinding capacity of imprinting sites towards target molecules was also determined.Furthermore,the adsorption isotherm of the target molecules vapor on the imprinting column was obtained according to the chromatographic outflow curve of the target molecule at different injection volumes.The results showed that the rebinding capacity between the imprinting sites on the surface of molecularly imprinted polymer and the target molecule was stronger than between the MIPs and the terpineol.This can also be deduced by a higher value in the adsorption amount for myrtenal than that for terpineol.