Electrochemical oxidation of dopamine in the presence of sulfhydryl compounds: Application to the square-wave voltammetric detection of penicillamine and cysteine

Shahrokhian, S ; Sharif University of Technology | 2006

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  1. Type of Document: Article
  2. DOI: 10.1016/j.electacta.2005.12.006
  3. Publisher: 2006
  4. Abstract:
  5. Electro-oxidation of dopamine at a glassy carbon electrode was investigated in the presence of some biologically important thiols (R-SH), e.g. cysteine and penicillamine. Results of cyclic voltammetric studies together with the spectrophotometric foundations via Ellman's test during the controlled-potential coulometry show a nucleophilic addition/reduction of thiol to the electrochemically generated dopaminoquinone by a 1 + 4 Michael addition. The resulting ring substituted substrate (as RS-form) is more easily oxidized leading to an increase in the anodic current of dopamine, which is proportional to the concentration of thiol. The square-wave voltammetry (SWV) were applied as a very sensitive voltammetric detection method for the detection of cysteine and penicillamine. A linear response from 0.10 to 2.5 μM with a detection limit of 0.08 μM is resulted by the voltammetric determinations for penicillamine. The effect of other biological thiols, such as N-acetyl cysteine, glutathione, methionine, captopril and mercaptoglycine were also assessed and found to present no appreciable change in the voltammetric response of dopamine. The proposed method can be considered as a relatively selective method for the voltammetric detection of penicillamine and cysteine. The practical utility of the method was investigated in the determination of thiol species in pharmaceutical preparations. © 2005 Elsevier Ltd. All rights reserved
  6. Keywords:
  7. Carbon ; Coulometers ; Drug products ; Electrodes ; Oxidation ; Controlled-potential coulometry ; Dopamine ; Square-wave voltammetry (SWV) ; Electrochemistry
  8. Source: Electrochimica Acta ; Volume 51, Issue 20 , 2006 , Pages 4271-4276 ; 00134686 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0013468605013836