Exchange current determination and time-dependent effects for model liquid membrane ion-selective electrodes

✍ Scribed by R.D. Armstrong; A.K. Covington; G.P. Evans; T. Handyside

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 419 KB
• Volume: 29
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(84)87166-2

✦ Synopsis

Exchange

currents have been determined using impedance measurements on liquid membranes consisting of a solution of valinomycin in 2,3aimethylnitrobenzene, supported on a cellulose acetate filter.

Various time-dependent

elk& have also been investigated by the same method. This valinomycin-based membrane provides a model system for some commercial ion-selective electrodes. The results indicate that potassium ions readily cross the water/liquid membrane interface, whilst sodium ions are largely excluded from the membrane. A complex situation appears to exist, whereby a general increase in bulk membrane resistance is offset to a greater UC Iesser extent (depending on the cation in the contacting solutions) by a reduction in resistance of the membrane phase due to cation uptake.