Cadmium Selective PVC-Membranes Sensor Based on 1, 2-Bis (Quinoline-2-Carboxamido) -4-Chlorobenzene as a Neutral Carrier

Abstract

The 1, 2-bis(quinoline-2-Carboxamido)-4-chlorobenzene (H2Clbqb) was used as an excellent ionophore in the construction of a cadmium(II)-selective PVC-based membrane sensor. The influences of membrane compositions on the potentiometric response of the electrodes have been found to substantially improve the performance characteristics. The best performance was obtained with a membrane composition of (H2Clbqb) (5%): PVC (31%): DBP (61%): NaTPB (3%). The sensor shows a Nernestian response for cadmium ions over a wide concentration range (1.0times106 to 1.0 times 10-1 mol.L-1) with slope of 30.3 plusmn0.4 mV decade1. The limit of detection was 8.0 times10-7 mol.L-1. It illustrates a relatively fast response time in the whole concentration range (< 10 s) and it can be used for at least 8 weeks without any divergence in potential. The electrode can be used in the pH range from 2.4 to 9.0. The selectivity coefficient of some alkali, alkaline earth, transition and heavy metal ions towards Cd2+ion have been determined. The results show proposed Cd sensor is selective over a number of mono, bi- and trivalent cations such as Pb2+, Fe3+, Ni2+, K+, and Mg2+. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of cadmium in real samples. It was successfully applied for the direct determination of Cd2+ in standard and real sample solutions.