Potentiometric Membrane Electrode for Cr(III) Ion Based on a New Aryl Amide Bifunctional Bridging Ligand as a Neutral Carrier

摘要

A novel Cr(III) ion-selective electrode is constructed by incorporating a new aryl amide bifunctional bridging ligand, 2,2'-bis {[(2 ''-benzylaminoformyl)phenxoyl]methyl}-diethylether (BBPMD) as a neutral carrier into the PVC matrix. The proposed electrode, with optimum membrane composition, exhibits an excellent near-Nernstian response for Cr3 ion ranging from 2.8 x 10(-6) to 1.0 x 10(-1) mol/L with a detection limit of 8.6 x 10(-7) mol/L and a slope of 19.5 /- 0.2 mV/dec in pH 3.0 nitrate buffer solution at 25 degrees C. It has an appropriate response time, suitable reproducibility, and good selectivity towards Cr3 ion. The operational pH range of the proposed electrode is 2.5-6.5. The response mechanism was discussed in view of UV-vis spectroscopy and the A.C. impedance technique. The excellent analytical features of the proposed electrode could lead to its successful application as an indicator electrode in potentiometric titration of Cr3 ion and in the direct determination of Cr3 ion in tea leaves and coffee samples.

关键词