Research And Application Of Molecularly Imprinted Purification Technology For Zanthoxylum

Molecularly imprinted technology refers to a kind of experimental preparation technology for obtaining polymers which can match with a target molecule at the spatial structure and binding sites,the synthesized polymers is called molecularly imprinted polymers（MIPs）.MIPs have the advantages such as preparation of simple,strong ability of adsorption,recyclable of template molecule,and so on.So there have a great significance for developing this technology.Numb-taste components which belong to a class of long unsaturated fatty amides carbon chain are the main hemp taste components in Zanthoxylum.Numb-taste components have many functions.They are now widely used in food,medicine,cosmetics and other aspects.However,the extraction of numb-taste components is very difficult.But,the emergence of molecularly imprinting technique can provide a new research approach for the separation of numb-taste components.The numb-taste components can’t be eluted easily because they have many unsaturated carbon-carbon double bonds at its molecular structure which can react with crosslinking agent to form macro-molecular structure when they were used as a template molecule.Therefore,our study had synthesized one king of analogues which its molecular structure is similar to the numb-taste components’molecular structure but don’t have unsaturated carbon-carbon double bond in its structure.Basis on this,two kinds of MIPs（MIPs1 and MIPs2 respectively）were prepared by surface molecularly imprinting and bi-functional monomers,and the solid phase extraction column for Zanthoxylum was prepared by using this two kinds of MIPs as filler.The results of the experiment are as follows:1.Preparation and properties of molecularly imprinted polymer of Zanthoxylum based on surface molecularly imprinted.（1）Through the computer molecular simulation technology,the best compatible functional monomer and pore forming agent for molecularly imprinted polymers of Zanthoxylum were methyliminodiacetic acid and acetonitrile,and the best proportion of template molecule between functional monomer was 1:4.（2）The MIPs1 was prepared by surface molecularly imprinted method.When the MIPs1 were prepared by 1 mmol LM,4 mmol methyliminodiacetic acid,60 mL acetonitrile,17.93 mmol EDMA,1.32 g silane silica gel and 32.62 mg AIBN,the specific adsorption capacity of the molecularly imprinted polymer is the strongest.（3）Kinetic adsorption experiments showed that the equilibrium adsorption time of MIPs1 for numb-taste components was 7 h,and its saturated adsorption capacity and specific adsorption factor can up to 30.848μg/mg and 3.028.The adsorption process is well fitted with the quasi first order kinetic model.Isothermal adsorption experiments showed that the adsorption capacity of MIPs1 to numb-taste components increased rapidly when the concentration of numb-taste components less than 200.0μg/mL,and increased slowly when the concentration of numb-taste components greater than 200.0μg/mL.The isothermal adsorption process is well fitted with the Langmuir model.2.Preparation and properties of molecularly imprinted polymer of Zanthoxylum based on bi-functional monomers.（1）Use the molecular structure analogues of numb-taste components as template molecule and the 2-VP andβ-CD as bi-functional monomers to prepare MIPs2.Through the UV full band scanning,the ratio of template molecule and 2-VP andβ-CD were determined as 1:2:2.（2）The MIPs2 was prepared based on bi-functional monomers method.By single factor experiment and orthogonal experiment,the optimum process conditions for the preparation of the molecular imprinted polymer is A₁B₂C₃D₂,that is,at 50℃,when adding 30 mL dimethyl sulfoxide,24 mmol EDMA and 50 mg AIBN to the 1 mmol the molecular structure analogues of numb-taste components,the synthesized molecularly imprinted polymers has good adsorption capacity and selectivity to numb-taste components.（3）Kinetic adsorption experiments showed that the equilibrium adsorption time of MIPs2 for numb-taste components was 11 h,and its saturated adsorption capacity and specific adsorption factor can up to 45.04μg/mg and 3.23.The adsorption process is well fitted with the quasi two stage dynamics model.Isothermal adsorption experiments showed that the adsorption capacity of MIPs2 to numb-taste components increased rapidly when the concentration of numb-taste components less than 204.3μg/mL,and increased slowly when the concentration of numb-taste components greater than 204.3μg/mL.The isothermal adsorption process is well fitted with the Freundlich model.3.Preparation and application of molecularly imprinted solid phase extraction column for Zanthoxylum Zanthoxylum.（1）Use MIPs1 and MIPs2 as the fillers to prepare the molecularly imprinted solid phase extraction column of the numb-taste components.The experiment results showed that the effect of column’s separation and enrichment to the numb-taste components is the best when the solid phase extraction column was prepared by using MIPs2 as filler,dichloromethane as sample solvent at a flow rate of 1.5 BV/min,acetone as washing reagent,methanol/acetic acid（9/1）as eluent.Use the prepared column to separate and purify the numb-taste components from the oleoresin,in results,the purification of the numb-taste components had increased from 23.34±1.21%to 92.40±1.41%.（2）Further expand the column,and then use the expanded column to separate and purify the numb-taste components from original liquid which include a lot of numb-taste components.The results showed that there are light yellow crystals after the solution recrystallized in petroleum ether at-20℃.And its purity is 90.24%,which is close to the purity of the original column 92.40%.It shows that the ability of separating and enriching the numb-taste components of pepper is not weakened.