Analytical Sciences

Abstract − Analytical Sciences, 19(2), 229 (2003).

Chemically Modified Carbon Paste Electrode for Iodide Determination on the Basis of Cetyltrimethylammonium Iodide Ion-Pair
Mohamed Noor El-Deen ABBAS
Microanalytical Laboratory, Applied Organic Chemistry Department, National Research Center, Dokki, Cairo, Egypt
A new carbon paste electrode (CPE) for the determination of iodide ion based on a cetyltrimethylammonium iodide (CTMAI) ion pair as an electroactive material is described. The electrode shows a linear response for iodide ion over the concentration range of 4 x 10-5 M to 1 x 10-1 M with a lower detection limit of 4 x 10-5 M at 25°C. The electrode has a Nernstian slope of -55.0 ± 0.4 mV/decade and a fast potential response of 45 s, which is almost constant over a pH range of 5.0 - 9.0. Selectivity coefficient data of the CTMAI-CPE for some common ions show negligible interference, and the electrode has high selectivity towards the iodide ion. An average recovery of 101.83% with a relative standard deviation of 1.53% has been achieved for the determination of iodide in Flaxedil (gallamine triethiodide) ampoules, a muscle relaxant drug. The electrode has been examined for the determination of iodide in saline water; the results were found to compare favorably with those obtained using Metrohm iodide ISE. The electrode has been utilized as an end-point indicator electrode for the determination of Hg(II) and phenylmercury(I) in their aqueous solutions using potentiometric titration with a potassium iodide standard solution.