pH measuring instruments record the pH value of a substance and determine the strength of the acidic or alkaline effect of a hydrous solution. As a logarithmic parameter, it is defined by the decadic logarithm of the oxonium concentration multiplied by -1. The determination and recording of pH value is of great importance for many chemical processes. The direct monitoring of pH value allows quality criteria for many different products and systems (pharmaceuticals, foodstuffs, plastics industries etc.) to be maintained or improved.
