Preparation and characterization of carbon paste electrode modified with tin and hexacyanoferrate ions

A carbon paste electrode was modified chemically using Sn(II) or Sn(IV) chlorides and hexacyanoferrate(II) or hexacyanoferrate(III). The electrochemical behavior of such SnHCF carbon paste electrodes was studied by cyclic voltammetry. The study revealed that Sn(IV) and hexacyanoferrate(II) yield the best results. This electrode showed one pair of peaks: the anodic and cathodic peak at the potentials of 0.195 and 0.154 V vs. SCE, respectively, at a scan rate of 20 mV s-1 in a 0.5 M phosphate buffer as the supporting electrolyte. The SnHCF modified electrodes were very stable under potential scanning. The effects of pH and alkali metal cations of the supporting electrolyte on the electrochemical characteristics of the modified electrode were studied. The results showed that cations have a considerable effect on the electrochemical behavior of the modified electrode. The diffusion coefficients of hydrated K+ and Na+ in the film, the transfer coefficient and the electron transfer rate constant were determined