The Preparation And Application Of Molecularly Imprinted Sensor Based On The Carbon Nanotubes Modified Electrode

In order to improve the detection sensitivity and accuracy, we modified the electrode by carbon nanomaterials. To improve the selectivity of the electrode, molecularly imprinted technique(MIT) was applied to the electrode. Both of these topics are recent research interests in the electrochemical community. In this thesis, novel amperometric sensors based on electropolymerized moleculary imprinted polymer and nanomaterials were used to detect salbutamol and clenbuterol. The electrochemical kinetics properties of reaction processes were discussed based on the experimental results. Effects of various experimental conditions were investigated, including pH value of supporting electrolyte, scanning rate etc. The main points are as follows:A sensor for the determination of salbutamol was prepared based on electropolymeried molecularly imprinted polymer and single-walled carbon nanotubes(SWNTs) modified. The poly(o-phenylenediamine) film was prepared by the cyclic voltammetric deposition of o-phenylenediamine in the presence of salbutamol. The template was removed by electrochemical method. Effects of experimental conditions such as pH value of supporting electrolyte, scanning rate, incubation time were investigated. The sensor response sensitively to salbutamol over a linear range from 7.94×10^-8 to 1.36×10^-5mol/L and a detection limit as low as 6.08×10^-8mol/L was obtained. This sensor provided an ef?cient way for eliminating interferences from compounds with similar structures to that of salbutamol. The sensor was successfully applied to detection of salbutamol in pork meat with the recovery rates between 92.1%-113%.We have combined the use of MIPs and multi-walled carbon nanotubes(MWNTs) to construct an electrochemical sensor that is capable of indirectly detecting clenbuterol. The sensor was prepared by electropolymerizing o-phenylenediamine (o-PD) on a glassy carbon electrode which was modified by MWNTs in the presence of template clenbuterol. The template can be quickly removed by acetonitrile solution. Ferrocyanide was used as the mediator between the imprinted electrodes and substrate solutions containing clenbuterol. When the modified electrode was incubated in solution containing clenbuterol, the cavities in film were partially occupied by clenbuterol, which would lead to the decrease of current signal produced by ferrocyanide. Cyclic voltammograms in 5mmol/L K3[Fe(CN)6] solution were performed after the modified electrode was incubated in solutions containing clenbuterol of different concentration for 20 min. The linear range was found to be 4×10^-8 to 6.64×10^-6 mol/L and the detection limit was calculated to be 8.12×10^-9 mol/L based on the 3σof blank signals. The linear calibration graphs for the clenbuterol determination can be described by the following equation, Ipa (μA)=4.8943×c(μmol/L)+2.44, and the correlation coefficient was 0.9947.Electrochemical behaviour of clenbuterol at the fullerene-C₆₀-modified carbon electrode was investigated using differential pulse voltammetry (DPV). The modified film became conductive when it was electrochemically reduced in 1mol/L KOH solution. The formation of KnC₆₀ may accountable for the increase in conductivity and the reduced film was quite stable even on exposure to air. Calibration plot having good linearity with a correlation coefficient 0.9916 was obtained in the concentration range from 1×10^-7mol/L to 1×10^-5 mol/L and the detection limit was estimated to be 4.06×10^-8 mol/L.