pH can be determined more accurately with a pH meter that includes a probe, electrode, and display. There are a variety of pH electrodes available where glass electrodes are commonly used. Various glass electrodes are also available in the market. Each glass electrode has special properties and must be carefully selected depending on the measurement application. Because the process of taking pH measurements changes the glass membrane of a glass pH electrode over time. Due to exposure to water, alkaline ions dissolve from the glass surface and the oxide groups of silicates are converted into OH groups causing a source layer. The use of a special pH glass electrode membrane is a reproducible equilibrium between the solution and the glass surface, depending only on the concentration of hydrogen ions in the solution and the source layer.
In the glass electrode pH determination method, the recognized pH of a reference solution is measured with two electrodes, a glass electrode and a reference electrode, and the voltage generated between these electrodes is determined. The change in pH between the solution outside and inside the membrane generates an electromotive force proportional to this difference in pH.