Carbon paste electrodes electrochemically modified with cyclodextrins

Abstract.

Cyclic voltammetry was used in order to obtain carbon paste electrodes (CPEs) modified with α- and β-cyclodextrins (CPE_α-CD, CPE_β-CD) in HClO₄ media as electrolyte. The modified CPEs were obtained by applying 30 potential cycles, thus forming on the substrate a film with electroactive characteristics; a rise in current for the anodic and cathodic peaks became apparent as the number of cycles increased. Such behaviour confirmed the CPE modification by the species mentioned. The CPE_α-CD and CPE_β-CD exhibited significant stability before various electrolytes. In order to evaluate the sort of modification attained on the CPEs, a study was conducted, varying the potential scan rate, that confirmed the CD's presence. The modified electrodes were used to determine Pb(II) ions in solution within the range from 1×10^–5 M up to 1×10^–3 M. The CPE_α-CD and CPE_β-CD electrochemical response was studied by means of anodic stripping voltammetry of the Pb(II) ions, thereby giving a linear relation between the current for the anodic peak as a function of Pb(II) concentration with r ²=0.996 for the CPE_β-CD and 0.992 for the CPE_α-CD.