A novel modified carbon paste electrode for the determination of chromium (III) in water sample

Two kinds of modified carbon paste electrodes for chromium (III) ion based on zeolite as ionophore were prepared. 3-methyl-pyrazol-5-one (MP) was used as modifier in sensor 1. Sensor 1 exhibits a Nernstian response for Cr(III) ions over a wide concentration range from 1 × 10–6 to 1 × 10-2 mol·L–1 with a slope of 19.8 ± 0.1 mV·decade–1.Sensor 2 was modified by using chlorinated nanotubes. This sensor shows a Nernstian response for Cr(III) ions over a concentration range from 1 × 10–7 to 1 × 10-2 mol·L–1 with a slope of 19.74 ± 0.1 mV·decade–1. Some parameters were optimized for two sensors such as pH of solution, composition of membrane and response time of electrode. And results were compared. They were successfully applied to direct determination of chromium (III) in water samples and as an indicator electrode in potentiometric titration of Cr(III) with EDTA.