Fabrication of Carbon Paste Electrodes Modified with Multi-walled Carbon Nanotubes for the Potentiometric Determination of Chromium(III)

In this research, different electrodes were made by combining certain percentages of carbon paste for a range of cations. Then, ligand selectivity was calculated for each cation using a potentiometric method to identify the most sensitive cation. A modified carbon paste electrode was applied to the quantification of chromium cation based on carbon nanotubes. In addition, paraffin, graphite, and 1,13-bis(8-quinolyl)-l,4,7,10,13-pentaoxatridecane were utilized in the manufacture of the electrodes. To get an optimum composition, D-optimal test design method was employed to increase electrode sensitivity and placement accuracy. Upon combining optimal percentages, this electrode showed the Nernstian response within the concentration range of 1.0 × 10–10–1.0 × 10–2 M, slope of 19.63 mV/decade with a detection limit of 3 × 10–11 M. The potential was found to remain constant within the pH range of 5.0–9.0, while a gradual deviation was observed outside this range.