Selective detection of Cu2+ ions using a mercaptobenzothiazole disulphide modified carbon paste electrode and bismuth as adjuvant: a theoretical and electrochemical study

A novel type of mercaptobenzothiazole disulfide (MBTS) modified carbon paste electrode (CPE-MBTS) was developed in the present study. DFT calculations identified an enhanced electrophilic character, and conductance of the modified electrode's interface, through bismuth coadsorption with the studied metal cations. Also, the strong binding energy of Cu2+ on the MBTS adsorption sites facilitates its selective and quantitative detection. Experimentally, the electrode was able to detect Cd, Cu and Pb, showing greater affinity for Cu, so the electrochemical study was focused on optimizing the selectivity and sensitivity of CPE-MBTS towards this metal. The detection of copper was done by square wave anodic stripping voltammetry (SWASV), yielding a LOD and LOQ of 0.34 ppm and 1.02 ppm, respectively, with good repeatability. The analysis of real samples showed the reliability of this electrode for the detection of Cu2+ in different types of waters.