According to Nernst Equation, in a chemical reaction
The potential of this reaction is given by the equation
Diagram of the glass electrode can be represented as:
The H+ ion exchange with the glass membrane to produce the inner and outer potential E1 & E2
By measuring the boundary potential (Eb) the relation between Eb and pH is:
Which E10, E20 are the formal potential, the [H+]Glass is constant and the inner proton ion concentration [H+]2 is invariable as constant. The equation can be expressed as:
Due to the proton ion at the glass membrane and the inner proton ion concentration will change after measuring, the 𝐸𝑘′ will be changed. So the glass electrode needs to be calibrated before use.
According to Nernst Equation, in a chemical reaction
The potential of this reaction is given by the equation
Humming Probe strip electrode modify the proton ion selective membrane at the electrode surface which having the redox reaction with proton ion, the diagram can be represented as:
According to Nernst Equation, the electrode potential is
Due to the precision and the consistency of the strip electrode, the 𝐸0 are the same for every electrode. And the strip electrode need not to be calibrated.
