Carmine Detection Using PEDOT:PSS/AuNPs/CA Modified Screen-printed Carbon Electrode

Carmine is an azo dye widely used in the food processing industry with bright colors,strong dyeing power and low price.Studies have found that long-term high intake of carmine is harmful to human health.T Therefore,it is urgent to develop a rapid and accurate detection method for carmine with high sensitivity and selectivity.Molecular imprinting electrochemical sensor(E-MIPs)is a kind of detection device that combines molecular imprinting technique with electrochemical sensors.That molecular imprinted polymers(MIPs)as the identification element of the E-MIPs have specific binding with the target materials that causes current response changing.The electrochemical signal is related to the concentration of the measured objects.In this paper,a high sensitivity and quantitative detection of Carmine molecularly imprinted sensor was successfully constructed.(1)the screen printing electrode was prepared,and three conductive materials were modified by electrochemical method on the electrode,namely,conductive polymer poly3,4-ethylenedioxythiophene:polystyrene sodium sulfonate(PEDOT:PSS),gold nanoparticles(AuNPs)and beta-mercaptoethylamine(CA).PEDOT:PSS and AuNPs polymerization on the electrode by the method of cyclic voltammograms.CA positively charged,through the Au-S bond links on AuNPs.The electrode conductivity is enhanced.(2)Molecularly imprinted polymers were prepared.The molecularly imprinted polymers were composed of template molecules,functional monomers and crosslinkers.When the ratio of template molecules,functional monomers and crosslinkers was 1:9:2,the performance of molecularly imprinted polymers reached the optimal level.(3)Molecular imprinting sensor was prepared.When 10 mg/mL polymer agar powder solution was selected and coated with 6_L,the molecularly imprinted polymer film reached the optimal state,which could recognize carmine specifically.When the adsorption time of the sensor for carmine is 10 minutes,the optimum adsorption time is to reach the maximum carmine adsorption capacity.(4)In the experiment,the selective recognition ability of the molecularly imprinted sensor was studied.The carmine and interfering substances of the same concentration were detected.The current response of the sensor is the most obvious and,the selectivity is high.(5)The reproducibility of molecularly imprinted sensors were studied.The electrodes prepared under the same conditions were placed in the same concentration of carmine solution for 3 times relative standard deviation(RSD)were 1.27%.The results demonstrated that the sensor had an excellent repeatability.(6)Under the optimal preparation conditions,potassium ferricyanide was used as the background detection solution,and the linear detection range of coumarin over 9 nM to 3900 nM.The limit of detection(LOD)was 6.05 nM(S/N=3).Using citric yellow and other molecules similar to carmine as interfering substances.To investigate the applicability of the sensor in actual samples detection,the content determination of carmine in drink was carried out.The recovery rate of the sensor was between 99.8%and 100.79%,while RSD was 1.79%?2.9%.The sensor has high sensitivity,excellent selectivity and fast response,and is expected to be widely used in actual sample detection.