Potassium ion-selective electrode

DETAILED DESCRIPTION OF THE INVENTION The dry-operative potassium ion-selective electrode comprises: (a) a metal/metal salt reference electrode; (b) the electrolyte layer; and (c) a potassium ion-selective membrane.
The electrodes are made by a process and using components which are described in U.
S.
Pat.
No.
4,214,968 (noted hereinabove), the disclosure of which is hereby incorporated by reference.
As used throughout this specification and in the claims, the expressions, "dry-operative", "dried" and "uniform" have the meanings defined in that patent.
The use of the hydrophilic binder in the electrolyte layer is optional, but preferred.
The electrodes of this invention can be used to determine the concentration of potassium in an aqueous solution, e.
g.
biological fluid such as whole blood, intracellular fluids, blood sera and urine.
Generally, a portion of the solution to be assayed is brought into contact with the dry-operative ion-selective electrode described hereinabove which is capable of generating a potential related to the potassium ion concentration.
Subsequently, the difference in potential between the portion of aqueous solution and the reference electrode is measured.
Preferably, a drop of the aqueous solution is spotted onto the potassium ion-selective membrane of such electrode with a pipette or other suitable means, but other ways of contacting the electrode with the solution are acceptable.
The conductive metal layer comprises any suitable conductive metal of the well-known types which have been used in such electrodes.
Particularly useful conductive metal layers include suitably thin layers of silver, nickel and platinum.
The salt layer in contact with the conductive layer comprises substantially any insoluble salt of the metal of the conductive layer which establishes a fixed interfacial potential with the metal of the conductive layer.
Such layers are well known.
These layers generally comprise a salt of the metal which is a product of the oxidation of the metal, as, for example, AgCl, Hg