A bismuth (II) selective modified carbon paste electrode with multi-walled carbon nanotubes for potentiometric analysis in real samples

A novel modified carbon paste electrode with Amino-Functionalized multi-walled carbon nanotubes (F-MWCNT) based on -schiff base ( 2-thienyl pyridine ) was prepared for potentiometric determination trace amounts of bismuth (III) in real solution. This sensor showed excellent sensivity, highly selectivity to Bi (III) compared with other cations and very low detection limit. The uniqe physicochemical properties of carbon nanotubes (CNTs) improved sensing and performance of bismuth sensor [1]. Central composite chemometrics design (CCD) and response surface methodology (RSM) was applied to evaluate the effects of significant and independent parameters, multivariate optimization and to gain better results [2]. Four factors containing ionophore, F-MWCNT, graphite powder and pH were investigate in twenty eight completely randomized trials CCD. So, the optimized bismuth sensor with the best amounts of ingredients in the optimal condition exhibits a nernestian slope of 19.325 mv/decade in the linear dynamic range of 1 × 10-10 to 1× 10-3 with detection limit of 1.057 × 10-10 The optimized electrode shows a fast response time less than 10s and applicable for 8 consecutive weeks without any change in PH range 3.8 - 10.0. The molecular geometric optimization and vibrational frequencies of synthesized ionophore and complex ( ionophore-Bi (III) ) in the ground state have been calculated by using B3LYP with 6-31G ( d , p ) basic set in solution phase [3].