Fully automatic determination of the total, calcium and magnesium hardness of water samples using photometric titration

This Application Note describes the determination of overall hardness in addition to that of calcium and  magnesium in water samples by means of the Optrode (610 nm). The total hardness is determined with  EDTA as titrant and Eriochrome Black T as indicator. The calcium hardness is in turn determined with EDTA and with calconcarboxylic acid indicator. The magnesium hardness is the difference between total hardness and calcium hardness.