Polyazulene Based Materials for Heavy Metal Ions Detection. 4. Search for Conditions for Thiophen-Vinyl-Pyridine-Azulene Based CMEs Preparation

The present work is connected to the study of electrode conditioning issues for the chemically modified electrodes (CMEs) prepared based on 2,6-bis((E)-2-(thiophen-2-yl)vinyl)-4-(5-isopropyl- 3,8-dimethylazulen-1-yl) pyridine (L). L is irreversibly electrooxidized to polymers leading to L-CMEs. The recognition experiments are the final test of chosen parameters (electropolymerization potential and charge in controlled potential electrolysis (CPE), anodic limit of the overoxidation cycles (OC), number of OC, anodic limit of the equilibration cycles (EC), number of EC, pH of the buffer solutions for HMs accumulation, complexation time, potential and time of reduction). The evidence of film deposition resulted by the change of ferrocene symmetrical signal characteristics on bare electrode in ferrocene solution was the simplest way to prove the formation of L-CMEs. However, finding the best electrode equilibration conditions turned out to be a source of increasing the analytical performance for the CMEs, especially those dedicated to the detection of Pb. The paper underlines the importance of understanding the role of each varied parameter, and of carrying out a systematic study of each possible variable. Optimum conditions for Pb ions analysis, using this new thiophen-vinyl-pyridine-azulene based CMEs, have been established, in order to get the best conditions for its detection in water.