Document Detail

Electrochemical behavior of a covalently modified glassy carbon electrode with aspartic acid and its use for voltammetric differentiation of dopamine and ascorbic acid.
MedLine Citation:
PMID:  15997381     Owner:  NLM     Status:  MEDLINE    
Aspartic acid was covalently grafted on to a glassy carbon electrode (GCE) by amine cation radical formation in the electrooxidation of the amino-containing compound. X-ray photoelectron spectroscopic (XPS) measurement and cyclic voltammetric experiments proved the aspartic acid was immobilized as a monolayer on the GCE. Electron transfer to Fe(CN)6(4-) in solution of different pH was studied by cyclic voltammetry. Changes in solution pH resulted in the variation of the charge state of the terminal group; surface pK(a) values were estimated on the basis of these results. Because of electrostatic interactions between the negatively charged groups on the electrode surface and dopamine (DA) and ascorbic acid (AA), the modified electrode was used for electrochemical differentiation between DA and AA. The peak current for DA at the modified electrode was greatly enhanced and that for AA was significantly reduced, which enabled determination of DA in the presence of AA. The differential pulse voltammetric (DPV) peak current was linearly dependent on DA concentration over the range 1.8 x 10(-6)-4.6 x 10(-4) mol L(-1) with slope (nA micromol(-1) L) and intercept (nA) of 47.6 and 49.2, respectively. The detection limit (3delta) was 1.2 x 10(-6) mol L(-1). The high selectivity and sensitivity for dopamine was attributed to charge discrimination and analyte accumulation. The modified electrode has been used for determination of DA in samples, in the presence of AA, with satisfactory results.
Lei Zhang; Xiangqin Lin
Publication Detail:
Type:  Journal Article     Date:  2005-07-05
Journal Detail:
Title:  Analytical and bioanalytical chemistry     Volume:  382     ISSN:  1618-2642     ISO Abbreviation:  Anal Bioanal Chem     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-07-26     Completed Date:  2007-01-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101134327     Medline TA:  Anal Bioanal Chem     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  1669-77     Citation Subset:  IM    
Department of Chemistry, College of Life and Environment Science, Shanghai Normal University, Shanghai 200234, P. R. China,
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MeSH Terms
Ascorbic Acid / analysis*
Aspartic Acid / chemistry*
Carbon / chemistry*
Dopamine / analysis*
Electrochemistry* / instrumentation,  methods
Hydrogen-Ion Concentration
Reproducibility of Results
Sensitivity and Specificity
Reg. No./Substance:
50-81-7/Ascorbic Acid; 56-84-8/Aspartic Acid; 7440-44-0/Carbon

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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