Page 51 - Pharmaceutical Analytical Chemistry II - Pharm D Clinical- 07-PA202
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INDICATOR ELECTRODES
Ideal Indicator electrode responses rapidly and reproducibly to
changes in the concentration of the analyte ion

   Two classes of Indicator Electrodes
       - Metallic indicator electrodes
       - Membrane indicator electrodes

Metallic Electrodes
Types of Metallic indicator electrodes:

   1. Electrodes of the zeroth kind (Redox inert electrodes)
   2. Electrodes of the first kind
   3. Electrode of the second kind

1- Redox inert electrodes:

An Inert metal, It has no share in redox reaction.
It responds to the potential of the redox system with which it is in
contact
Example: platinum (Pt), gold, palladium
Pt electrode immersed in a solution containing Ce4+/ Ce3+

         E ind = E0Ce – 0.059 log [Ce3+] / [Ce4+]
( Application: Potentiometric titration using redox reaction)

2- Electrodes of the first kind: (for cations)

A metal in contact with a solution containing its own ion.

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