ABSTRACT
One interesting application of the electrode is its use in the determination of complexing agents such as the citrate ion and 8-hydroxyquinoline. It is important to distinguish between homogeneous and heterogeneous membranes used in ion-selective electrodes. The term "homogeneous" can be applied to those membranes in which a single phase is formed by the combination of reagents with a binding material such as polyvinyl chloride. Heterogeneous-membrane electrodes have been specifically reviewed a number of times. The active reagent which is held by the binding material must have a low solubility in water, it must be finely divided so that there is good contact between particles throughout the membrane, and, most important of ail, it must react selectively to the ion of interest. The original Pungor membranes are prepared by crushing the active material to the appropriate size and dispersing it in polysiloxane, using a laboratory kneading machine.
