Potential stability improvement in Pb2+ ion selective electrodes by applying hydrophobic polyaniline as ion-to-electron transducer

Electrode potential stability is a major challenge for solid-contact ion-selective electrodes (SC-ISEs), with the formation of a water layer in the ion-to-electron transducer being the main cause of electrode potential instability. To investigate this problem, hydrophilic polyaniline (PANI) nanofibers doped with H3PO4 (PANI-H3PO4, water contact angle (CA) 48 degrees) and highly hydrophobic polyaniline nanofibers doped with perfluorooctanoic acid (PANI-PFOA, CA 120 degrees) were prepared by electrochemical deposition and secondary doping, then used as the solid contact layer in the construction of Pb2+-ISEs. By studying the potential response of the fabricated Pb2+ ISEs to Pb2+ ions using chronopotentiometry and water layer tests as a function time, it was determined that Pb2+-ISEs containing hydrophobic PANI-PFOA as the solid contact layer offered superior stability potential and a longer life. The potential drift of the developed GC/PANI-PFOA/Pb2+-ISM electrode was only 21.62 +/- 4 mu V/h, while the potential drift of GC/PANI-PFOA/Pb2+-ISM electrode was 197.6 +/- 16 mu V/h, highlighting the benefits of a strongly hydrophobic SC layer in SC-ISEs construction.