Preparation And Application Of Xicaojing Molecularly Imprinted Electrochemical Sensor

Molecularly imprinted polymer(MIPs)is a class of new polymer materials with specific recognition capabilities,and after combining MIPs with electrochemical sensors,the sensors not only have high selectivity of imprinting polymers,but also have advantages of high sensitivity,low cost and rapid response.Molecular ly imprinted electrochemical sensors had been reported recently,but the report of simetryn sensor has not been found.In this paper,we synthesized MIPs(simetryn as template)through experiments on the basis of simulation results,and the molecular imprinting electrochemical sensor of simetryn was prepared and applied to the detection of simetryn in tobacco.The specific research contents are as follows:(1)In this paper,the imprinting system(simetryn as template)was designed at the WB97XD/def2 tzvp level based on density functional theory,and the interaction of template with monomer was computed in each binding sites.The results showed that 2-(trifluoromethyl)acrylic acid(TFMAA)was more suitable than methacrylic acid(MAA)for simetryn molecularly imprinted polymer system.The simulation of infrared spectra could help us to confirm the binding sites of polymers,compared with the infrared spectra of synthesized MIPs,the result confirmed the accuracy of computer simulation,which provided reference for the control of polymerization conditions.(2)According to the results of theoretical calculations,simetryne molecularly imprinting polymer(SMT-MIPs)were synthesized using SMT as template,TFMAA or MAA as functional monomer,by precipitation polymerization.By comparison,it was found that SMT-TFMAA-MIPs had smaller particle size and larger adsorption capacity than SMT-MAA-MIPs did.The selective adsorption experiments showed that the both MIPs had selective adsorption capacity for simetryn and the analogues,and the change of functional monomers will affect the specific adsorption of the prepared polymers.The SMT-TFMAA-MIPs was used as adsorbents in solid phase extraction and quantitatively detected by HPLC-MS.The results showed that the low detection limit was 2-10ng/mL and the recovery rate was 84.8-109.3% in a certain range.This method can be used in analysis of multiple triazine herbicide residues in tobacco,and compared with SMT-MAA-MIPs,the low detection limit of SMT-TFMAA-MIPs was more accurate.(3)The molecularly imprinted electrochemical sensor for SMT was prepared by thermal polymerization on the surface of glassy carbon electrode,and it has good selectivity,repeatability and stability.The linear range of this electrochemical sensor was 0.5-1?mol/L and 2-30?mol/L,and the low detection limit(S/N=3)was 0.13?mol/L.When SMT content in tobacco was detected by the sensor,the recovery rate was 76.30%-88.25%.This method can be used in analysis of multiple triazine herbicide residues in tobacco.