Detections Of Hydrogen Peroxide,Glucose And Dopamine By Using Iodine Ions As Electron Mediator

In this thesis,the structure,principle,classification and development process of electrochemical sensors were summarized.The iodine element and its electrochemical detection were also briefly introduced.The electrochemical analysis of H2O2,glucose and dopamine were achieved based on the two-step electrode process of iodine ions.The main contents are listed as follows.1.Glassy carbon electrode modified with gold nanoparticles(GCE/Au NPs)was prepared by dripping colloidal gold on the electrode surface and it was characterized by different methods.? all suffered from a two-step electrochemical process on GCE and GCE/Au NPs surfaces.Researches reveal that the catalytic oxidation of H2O2 could be achieved by using ? as the electron mediator.GCE/Au NPs was in favor of this process owing to its larger electrode area and better electroconductivity.Under the optimized conditions,the oxidation-peak current change of ?was found to be proportional to the H2O2 concentration from 10 ?M to 10 mM and the detection limit was 1 ?M.A sensitive electrochemical method for the H2O2 detection was developed.This sensor exhibited some advantages,such as fast response,simple preparation and good selectivity and it has been successfully applied to the detection of hydrogen peroxide in a disinfectant solution.2.Glassy carbon electrode modified with gold nanoparticles-glucose oxidase(GCE/Au NPs/GOx)was prepared by using GCE/Au NPs and GOx based on Au-S bond.The modified electrode was characterized by scanning electron microscope and electrochemical methods.GOx could catalyze the oxidation of glucose and produce H2O2 that was further catalytically oxidized by using ? as the electron mediator.Therefore,a sensitive electrochemical method for the glucose detection was proposed.Under the optimized conditions,the oxidation-peak current change of T was found to be proportional to the glucose concentration from 1 ?M to 10 mM and the detection limit was 0.069 ?M The developed sensor,which had some characteristics,such as simple preparation and good anti-interference ability,was expected to be applied in the detection of practical samples.3.Electrochemical activation of GCE was performed by cyclic voltammetric scan.The peak currents of r on the surface of the activated GCE was higher than those of unactivated GCE.Dopamine could be oxidized by I3-,resulting in that the latter was reduced to ?.An electrochemical method for the dopamine detection by using the ratio current measurement was developed based on the increase of the oxidation-peak current of ? and the decrease of oxidation-peak current of I3-Under the optimized conditions,the ratio current was found to be proportional to the dopamine concentration from 0.1 ?M to 10 mM and the detection limit was 0.08 ?M.The proposed method exhibited some merits including quick response,low cost and satisfactory selectivity.The determination of dopamine in an injection has been successfully applied by using this method.