Voltammetric characterization and determination of thallium(III,I) at a glassy carbon electrode modified with a film containing iridium oxide

Cyclic voltammetry of a 0.1 mM PdCl2, 0.2 mM Na2IrCl6 0.2 M K2SO4 mixture at a glassy carbon electrode results in the gradual accumulation of a film, which contains Pd(II) and iridium oxide, that promotes the quasi‐reversible oxidation of Tl(I). Cyclic voltammetry at 5 mV/s yields a peak potential difference of 35 mV at the modified electrode and about 700 mV at bare glassy carbon. The peak current for the linear scan voltammetric oxidation of 0.2 mM TI(I) in 1.0 M NaCl is directly proportional to the square root of scan rate up to 0.1 V/s. Both cyclic voltammetry and rotating disk voltammetry at modified electrodes provide data consistent with a two‐electron oxidation. The modified electrode is suitable for the determination of thallium by differential pulse voltammetry in the micromolar range.