In: Chemistry
Explain the working principle of an ion-selective electrode.
Ion selective electrode (ISE) involves use of a pH meter or an ion selective probe to identify and quantify each single dissolved ion in the solution. It works on the principle of Nernst equation and can measure both positive as well as negative ions in a solution without being affected by any interference of other dissolved components.
The transport of ions from an area of high concentration to low concentration through the selective binding of ions with the specific sites of the membrane creates a potential difference.
This potential is measured with respect to a stable reference electrode having a constant potential, and a net charge is determined. The difference in potential between the electrode and the membrane depends on the activity of the specific ion in solution.
The strength of the net charge thus measured is directly proportional to the concentration of the selected ion.