1993 Volume 42 Issue 6 Pages 375-379
The response properties of membrane-coated carbon rod electrodes toward the salicylate anion were investigated. New electrodes were prepared by incorporating bis(diphenylphosphino)propane (BDPPP) into a plasticized poly(vinyl chloride) membrane, and then coating it on a carbon rod surface. These electrodes were used for immersion into a solution containing a metal {Pd(II), Rh(III) or Cu(II)} and salicylate ions in order to form BDPPP complexes inside the membrane. Although the two other complexes responded to the salicylate ion, the electrode with the Cu(II) complex showed the following good response properties: a near-Nernstian slope of 5860 mV/decade, detection limit of 8×10-6 mol dm-3 and a response time of 56 s over a pH range of 4.59.5. The order of the selectivity coefficient for foreign anions roughly followed the Hoffmeister series. The interfering effects of acetate and benzoate ions were rather weak, as was the effect of the chloride ion, when compared to that of an electrode based on the tin (IV) porphyrin complex. BDPPP forms a 1 : 2 Cu(II)/ligand complex in which the exchange of counter anion produces the potential response.
