Carbon paste electrodes electrochemically modified with cyclodextrins

Cyclic voltammetry was used in order to obtain carbon paste electrodes (CPEs) modified with alpha- and beta-cyclodextrins (CPEalpha-CD, CPEbeta-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 CPEalpha-CD and CPEbeta-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 1x10(-5) M up to 1x10(-3) M. The CPEalpha-CD and CPEbeta-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 CPEbeta-CD and 0.992 for the CPEalpha-CD.