Synthesis Of Rhodamine B And Erythrosine Molecularly Imprinted Polymer And The Evaluation Of Its Adsorption Ability

Food colorants are an important part of food additives,and are important sensory indicators for food.Synthetic pigment because of its low cost and high stability,gradually replace the natural pigment,widely used in the food industry.however,the safety of synthetic pigment is low,excessive use will bring great threat to health of consumers.Due to the characteristics of synthetic pigment,resulting in its abuse in food,and even some banned add pigment also appeared in food,such as rhodamine B,Congo red and so on.In order to ensure the safety of food,strictly control the use of synthetic pigment,accurate pigment detection method is indispensable.However,the sample pretreatment for subsequent instrument precision detection plays an important role.At present,the more commonly used pretreatment method is solid phase extraction,although its streamline cumbersome steps in pigment extraction,has great advantages,but it lacks selectivity for pigment extraction,and the recovery rate is not high.Therefore,it is necessary to study a new adsorbent material,which can recognize the adsorption of the target substance.In this study,respectively illegally added pigment rhodamine B and legally added pigment erythrosine as the research object,the molecular imprinting technique was used to prepare the molecular imprinted polymer,which was used for the specific capture of target molecules in food.The research work of this thesis mainly includes the following contents:(1)The rhodamine B molecularly imprinted polymer was prepared by precipitation polymerization method.The polymerization conditions were optimized by changing the functional monomer type and the ratio of template and functional monomer.The results showed that the imprinting effect was better when acrylamide is used as the functional monomer and the molar ratio between the template and the monomer is 1: 4.Through the adsorption kinetics experiment,the isothermal adsorption experiments,selective adsorption experiment and the actual samples adsorption experiment to evaluate molecularly imprinted polymer,it was concluded that the rhodamine B molecular imprinted polymer had high affinity for template and had fast adsorption kinetics and large adsorption capacity,could specifically recognize rhodamine B in the complex actual sample.(2)The core-shell type erythrosine molecularly imprinted polymer was prepared by surface polymerization method with aminoized silica as the core and a layer of imprinted shell on its surface.Characterization of polymers by potentiometric and infrared spectroscopy revealed that the amino groups had been grafted onto the silica surface and successfully synthesized imprinted shell on the surface of the aminated silica.(3)The adsorption ability of the erythrosine molecularly imprinted polymer was evaluated by the kinetic adsorption experiment,isothermal adsorption experiment,and the test of the adsorption ability of MIP to erythrosine in food sample.The results showed that the imprinted polymer had been adsorbed on the target material in a short period of time,and had good adsorption capacity for the template.In the spiked experiment,erythrosine could be adsorbed from the complex sample at low concentration,and the recovery rate was high.The extraction process did not need the leaching step,which saved a lot of organic solvent.