| In present work,molecular recognition behavior for the molecularly imprinted polymers in liquid and gas phase media was discussed.Several molecularly imprinted polymers were prepared by using 2-isopentyl cyclopentanone,N-dimethylammonium nitrate and palmitic acid as target molecules,respectively.The imprinted polymers were characterized by scanning electron microscopy and infrared spectroscopy.The adsorption performance and its solid phase extraction application efficiency of target compounds were tested for the molecularly imprinted polymers in liquid phase environment.Using molecularly imprinted polymers as stationary phase of gas chromatography and template and its structural analogues as analytical materials,the recognition efficiency and adsorption thermodynamics of gaseous molecules were investigated by reverse phase gas chromatography.?1?A molecularly imprinted microspheres was prepared by precipitation polymerization using 2-isoprene cyclopentanone as virtual template.The surface chemical characteristics and particle size distribution of molecularly imprinted microspheres were investigated by fourier transform infrared spectroscopy and scanning electron microscopy.The adsorption kinetics,isotherm adsorption properties and adsorption selectivity of imprinted polymers toward rose ether were tested.The application efficiency of molecularly imprinted solid phase extraction of rose ether was investigated.The retention and separation properties were studied on the imprinted column was measured toward rose ether vapor by reverse phase gas chromatography.The relevant thermodynamic parameters of rose ether vapor on molecularly imprinted column were calculated.The results show that the adsorption of rose ether by molecularly imprinted polymer?MIPs?can reach equilibrium at 25 min and has fast adsorption kinetics.the selection factors of virtual template imprinted polymer for rose ether are 3.710 and 5.636 relative to geraniol and citronellol,respectively,and still have high selective adsorption ability for target compounds in mixtures containing rose ether(competitive adsorption amount is 18.02 mg g-1).Under optimized washing and elution conditions,the effective separation and enrichment of rose ether can be achieved by molecularly imprinted solid phase extraction with a recovery rate of 96.23%.In addition,molecularly imprinted polymers have good molecular recognition properties for gaseous target molecules.when the column temperature was 498 k,the retention time of rose ether and template molecules on the imprinted column was 32.17 and 68.00 min,capacity factors reached 71.62 and 152.50,respectively.These tested compounds have a high symmetry on the imprinted column with no obvious tail peaks,and the recognition of rose ether molecules by polymers shows a nonlinear retention pattern.When the temperature increased,the adsorption capacity of molecularly imprinted polymers on rose ether vapor showed an increasing trend,and the adsorption isotherms were almost linear,in accordance with henry law.Compared to non-imprinted polymers,molecularly imprinted polymers exhibit slightly higher adsorption free energy and adsorption enthalpy values for rose ether vapor,indicating higher affinity of imprinted materials for rose ether.Moreover,the thermodynamic results of adsorption between rose ether vapor and fixed phases show negative values of?Ga and?Ha,which may mean that the interaction between rose ether vapor molecules and imprinted polymers is a spontaneous exothermic process.?2?A N-dimethylnitrosamine imprinted polymer was prepared by precipitation polymerization and characterized by using scanning electron microscopy and infrared spectroscopy.Adsorption kinetics and isotherm adsorption behavior of molecularly imprinted polymers were tested in liquid-phase environment.The selective adsorption and application properties of N-dimethylnitrosamine were investigated.Gas phase retention behavior and related adsorption thermodynamic parameters of template molecules were investigated by inverse gas chromatography.The liquid adsorption study showed that molecularly imprinted polymers could achieve adsorption equilibrium at 50 min with a saturated adsorption capacity of 35.3 mg g-1,capacity factor for the template is 18.34,and relative to structural analogs,N-diethylnitrosamine and N-dipropylnitrosamine,the selection factors were 3.071 and 2.476.Gas phase adsorption showed that the retention factor of the imprinted column was 96.16,which was significantly higher than that of its structural analogues.When the column temperature is the same,its capacity factor for template molecules is higher than its structural analogues,up to 96.16,which shows high selective recognition performance for gaseous template molecules,and the adsorption process is a spontaneous exothermic adsorption process.When the sample volume is changed,the retention time of the compound changes.adsorption isotherms of molecularly imprinted polymers show a"s"shape,indicating the complexity of the adsorption process of polymer materials to gaseous compounds.?3?A palmitic acid imprinted polymers microsphere was prepared by precipitation polymerization.The morphology of molecularly imprinted polymers was observed by light microscope and surface chemical functional group characteristics studied by infrared spectroscopy.Adsorption kinetics,adsorption isotherm,adsorption selectivity,solid-phase extraction application performance and repeatability of molecularly imprinted polymers in liquid phase environment were tested.In additon,the molecular imprinting materials were used as the stationary phase in gas chromatography to identify its retention and adsorption capacity toward palmitic acid as probe molecule.Retention factor,adsorption isotherm and adsorption thermodynamics of imprinted columns as gas chromatography column were investigated.In liquid media,the molecularly imprinted polymer could reach the adsorption equilibrium at 60 min,with a saturated adsorption amount of 39.32 mg g-1,and adsorption was mainly chemical adsorption process.The static adsorption capacity for palmitate imprinted polymer toward was 40.70 mg g-1,higher than than that toward structural analogue.The molecularly imprinted polymer has also a high competitive adsorption capacity(competitive adsorption amount 32.82 mg g-1)toward target compound palmitic acid in the simulated mixture solution,a much higher value than that toward oleic acid(adsorption amount 13.15 mg g-1).Under optimized washing and elution conditions,palmitic acid can be effectively separated and enriched by molecularly imprinted solid phase extraction,with a recovery rate of 88.12%.As gas chromatography stationary phase,the molecular imprinting column possessed strong retention ability to template vapor molecules under the same chromatographic conditions,and retention time decreased with the increase of temperature.When the column temperature increased from 498.0 k to 548.0 k,the retention time of the two analytes decreased by 91.5%and71.3%,respectively,indicating that the retention of molecularly imprinted polymers to compounds is closely related to temperature.The adsorption thermodynamical parameters for the molecular imprinting column toward template vapor were obtained by theoretical calculation.It was found that the adsorption capacity for imprinted material toward gaseous template molecule was still stronger than that for the non-imprinted polymer.Adsorption isotherm of palmitic acid on the MIPs column was approximately linear,according with henry's law.Retention and selection of molecularly imprinted polymers at different carrier gas flow rates indicated that the carrier gas flow rate had great influence on the retention ability of molecularly imprinted polymers.While the molecularly imprinted polymer as the gas chromatographic stationary phase can effectively separate palmitic acid in the simulated mixture under suitable chromatographic conditions,with a separation degree of palmitic acid and linoleic acid of 1.132,the non-imprinted polymer can not separate the simulated mixture and the chromatographic peaks of several compounds overlap. |
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