Measurement of pH has always been, and still is, one of the most widely used analytical methods in the chemical industry. It is a fast and accurate measure of the acidity or basicity of all types of solutions. There are two main methods for measuring pH, the colorimetric method by using indicators and the electrochemical method by using electrodes.
The potentiometric measurement of pH in soils, which are usually aqueous suspensions with inorganic particles, and in creams, is very complicated because of the occurrence of the suspension effect. Two types of suspension effect are known. Suspension effect I is due to the Donnan potential at the phase boundary between the sediment and the equilibrium solution. Suspension effect II is due to an anomalous liquid potential at the boundary between the reference electrode and the sediment. In my work, I will describe both effects in more detail.
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