Important aspects influencing stability of the electrochemical potential of conductive polymer-based electrodes

In this article, important aspects influencing the signal stability of the potentiometric sensors based on various conductive polymers on platinum support are discussed. The initial step is the choice of a suitable cleaning method (mechanical stripping, burning out) of the platinum support. The second point consists in the selection of an appropriate procedure employed to mature the freshly prepared film on the metallic support (soaking, potential treatment, drying). The third crucial stage involves the application of a proper regeneration procedure (pH value of a buffer, anionic surfactant). The mentioned aspects have been tested using polythiophene, polyaniline, polypyrrole, poly(neutral red), poly(5,15-bis(2-aminophenyl)-2,8,12,18-tetraethyl-3,7,13,17-tetramethyl-porphyrine), poly(5,15,25,35-tetrakis(4-hydroxyphenyl)porphyrine) or poly(2,3-bis-(1H-pyrrol-2-yl)-quinoxalin-5-ol) as sensitive layers. The combination of the prepared electrodes into an electrode array (electronic tongue) and the development of a suitable protocol of the measurement allowed us to distinguish the individual brands of the Czech beers, specifically, Bernard 10°, dark Kozel 10°, Kozel 10°, Bráník 10°, Radegast, and Staropramen. Besides the platinum support, the conductive polymers were also deposited on a nonconductive support (membrane). The latter experiments demonstrated that the introduction of a conductive polymer as the outer layer onto poly(vinyl chloride) membranes led to the significant stabilization of their potentiometric response.