PbO2-based graphite-epoxy electrode for potentiometric determination of acids and bases in aqueous and aqueous-ethanolic media

The construction and analytical evaluation of a PbO2-based graphite-epoxy e lectrode sensitive to H3O+, based on incorporation of lead(IV) oxide in a g raphite-epoxy matrix, are described. The data obtained from a variety of ac id-base titrations in aqueous and aqueous-ethanolic media were compared wit h those obtained by use of a glass electrode tinder the same conditions. Th e proposed electrode provides a linear response in the pH range from I to I I with a slope of -58.7 +/-0.3 mV pH(-1) and -60.8 +/-0.2 mV pH(-1) in aqu eous and ethanolic media, respectively. The response time was less than 15 s and the lifetime of the electrode was at least eight months (ca. 5000 det erminations) and its performance is good in pH determination and end-point detection in potentiometric acid-base titrations in both aqueous and aqueou s-ethanolic media.