I use a nanomaterial-coated electrode to electrochemical detect dopamine. When the CV technique is used, the current shows excellent linear relationship to DA concentration. On the contrary, no linear relationship between the current and concentration could be observed when the DPV technique is used (please see the attached figure). Why?
Dear Guangwei: are you using the same concentration range for both CV and DPV ? Your DPV graph appears to have two linear ranges, at lower concentration and at higher concentration. Have you analysed the CV response over the same concentrations?
Thanks for your answer. The concentration ranges for CV and DPV measures are the same, from 0.1 to 500 uM.
Is the CV response diffusion controlled? Maybe there are some complications associated with diffusion/adsorption in the thin film that are exagerated by the current-sampling and differential nature of DPV.
Yes, the electrode exhibits a diffusion-controlled characteristic. And the electrode can really absorb DA molecules during the testing process,because very obvious redox peaks can be found in the CV and DPV curves after the electrode was rinsed and then measured in the blank electrolyte. So does the adsorptions have different effects on CV and DPV measurements? I am not so familiar with electrochemical theories. I learned from the books that compared with CV, DPV just eliminate the interfere from the charge current by a special potential applying program.
yes, adsorption can have a big impact on DPV. Can send me bu email some raw data (CV and DPV) ? I will try to interpret the reasons for non-linearity for you.
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