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Preparation Of Chemical Modified Electrodes And Its' Application In Flow Injection-Irreversible Biamperometry

Posted on:2009-10-15Degree:MasterType:Thesis
Country:ChinaCandidate:L B YuFull Text:PDF
GTID:2121360245468274Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
The study on the methods,principles and performance aspects of the chemically modified electrodes which contain designing,characterization and catalytic efficiency are discussed.In this paper,we construct and design the three types of chemically modified electrodes,apply to flow injection-irreversible biamperometric with the self-assembly modification,polymer modification,and access of nanoparticles modification.The mechanism of electrocatalysis oxidation to analysis material on modified electrode was studied.We take the theoretical investigation about oxidation current increases significantly under the effect of enhancement of electrc transfer at modified electrode comparison to that at the bare electrode.Its specific research as follows:1.L-cysteine self-assembled monolayers has been fabricated on the surface of gold electrode(L-Cys/SAM-Au/CME)by S-Au bond interaction,also the electrochemical behaviors of ferulic acid on the modified electrode were investigated.The method of self-assembled monolayers modified electrode is applied to establish in the flow-injection irreversible biamperometric analysis,the irreversible system is composed of electro-catalytic oxidation of ferulic acid on L-cysteine gold modified electrode and reduction of permanganate at the other bare gold electrode.The oxidative peak current increases linearly with the concentration of ferulic acid in the range of 5.0×10-7~8.0×10-5mol/L,linear regression equation:i(nA)=4.16×107 C+ 50,and in the range of 1.0×10-4~1.0×10-3mol/L, linear regression equation:i(nA)=5.6×106 C+300.The detection limit for ferulic acid is 1.2×10-7mol/L.This proposed method was applied to the analysis of sodium ferulate injection with satisfactory results.2.With the aid of a condensation agent DCC,the open-ended and carboxyl groups terminated MWCNTs(multi-walled carbon nanotubes)and L-Cys(L-cysteine)condensation reaction through the carboxyl and amino group,and the function of MWCNTs form self-assembled monolayers on gold electrode surface via bond of S-Au.Prepare the modified electrode of MCNTs-L-Cys-Au/SAMs by co-assembling on gold electrode surface with MWCNTs and L-Cys.Meanwhile,we take the investigation of optical spectroscopy and electrochemistry for modified electrode.Meantime,the mechanism of electrocatalysis oxidation to resveratrol on modified electrode was studied.The oxidative peak current increases linearly with the concentration of resveratrol in the range of 1.0×10-5~2.0×10-7 mol/L,linear regression equation:i(nA)=2.57×106 C-260,and in the range of 2.0×10-3~8.0×10-5mol/L,linear regression equation:i(nA)=1.57×107C-420.The detection limit for resveratrol is 8.0×10-8mol/L.This proposed method has the advantage of high selectivity and sensitivity.The disposal method of the sample is simple,and applied to the analysis of resveratrol in giant knotweed and red wine with satisfactory results.3.The Poly(L-threonine)modified electrode is prepared successfully by using cyclic voltammetric method at lead electrode.The optimum polymerization condition of L-threonine on lead electrode is studied,and the microscopic configuration of the surface of modified electrode also is characterized.The electrochemical behaviors of promethazine on the poly(L-threonine)lead modified electrode are studied.In pH 6.8 phosphate buffer solution (PBS),the oxidative peak current increases linearly with the concentration of promethazine in the range of 2.0×10-6~1.5×10-3mol/L,linear regression equation:i(nA)=1.97×107 C-300. The detection limit for promethazine is 8.5×10-7mol/L.This proposed method is applied to the analysis of promethazine tablet with satisfactory results.4.The multi-wall carbon nanotubes-modified glassy-carbon electrode(MWCNTs /GCE-CME)is prepared at the bare glassy-carbon electrode,and the micrographs of the MWCNTs/GCE-CME are obtained by device of scanning electron microscopy.The electrochemical behaviors of dipyridamole(DPD)on the modified electrode are studied.The oxidation peak current of DPD at the MWCNTs/GCE-CME under the effect of enhancement of surfactant are investigated.The mechanism is investigated.The oxidative peak current increases linearly with the concentration of DPD in the range of 1.5×10-6~1.0×10-3mol/L, linear regression equation:i(nA)=2.37×106 C-450.The detection limit for DPD is 8.0×10-7 mol/L.This proposed method was applied to the analysis of DPD tablet with satisfactory results by using MWCNTs/GCE-CME.
Keywords/Search Tags:irreversible biamperometric analysis, chemical modified electrodes, ferulic acid, resveratrol, promethazine, dipyridamole, determination
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