Study On The Fabrication Of Chemically Modified Electrodes And Their Applications

Chemically modified electrode,developed in the middle of the 70s of 20^th century,is the most active frontier in electrochemistry and electroanalytical chemistry,which has been widely applied in life science,environmental science,food science,analytical science and material science.Some special function groups can be selected on purpose to be polymerized on the surface of electrode and thus the polymer film modified electrodes are endowed with some particular qualities to have highly selective reactions as expected.Therefore,with its simple preparation method and long working life, chemically modified electrode is widely used in many fields.In this paper,the modified electrodes are prepared by some polymerizing special function groups onto the surface of electrode by chemical or electrochemical way.The properties of modified electrodes such as adsorbing capability and enrichment capability have been investigated.The modified electrodes have been successfully applied for the determination of Cu²⁺ ion and ascorbic acid.1.The L-Cys/Au electrode was prepared by using self-assemble and electrochemical cyclic voltammetry.The electrochemical properties of L-Cys/Au electrode and the adsorption behavior of Cu²⁺ on the electrode surface were studied.Cu²⁺ ion was adsorbed on the surface of L-Cys/Au electrode when the PBS(pH=6.86) containing Cu²⁺ ion was stirred.Reduction peak current(I_pc) of Cu²⁺ ion has a good linear relationship with logarithm of Cu²⁺ concentration in a certain Cu²⁺ concentration range.The detection limit for Cu²⁺ was 2.0 x 10^-10 mol/L.A new electrochemical method with highly sensitivity and selectivity for analyzing trace Cu²⁺ has been established.2.The L-glutamic acid/Fe(CN)₆^3- modified glassy carbon electrode has been prepared by electrochemical cyclic voltammetry.The anticathode stripping behaviors of Cu²⁺ ion on the modified electrode was investigated.The stripping peak current(I_pa) increased with an increase in concentration of Cu²⁺ and was linear with logarithm of Cu²⁺ concentration in the range of 1.0×10^-7～1.0×10^-3 mol/L.A new anticathode stripping voltammetry methode for the determination of trace Cu²⁺ was develpoed3.The poly-L-glutamic acid modified glassy carbon electrode was prepared by electrochemical polymerization.The electrochemical behaviors of the modified electrode were investigated.The modified electrode had good electrochemical response for ascorbic acid.The experimental conditions for the determination of ascorbic acid were optimized and the results showed that ascorbic acid in pH 4.0 buffer solution had steady oxidation peak on the surface of the poly-L-glutamic acid modified glassy carbon electrode in the scanning potential range of -0.2～1.0 V.The oxidation peak current(I_pa) has a good linear relationship with the concentration of ascorbic acid in the range of 2.0 x 10^-5～2.0×10^-3 mol/L with the detection limit of 2.0×10^-6 mol/L.The preparation of this electrode with good stability and repeatability is convenient.