Complexonometry

(also chelatometry, “trilonometry”), a method of titrimetric analysis based on the formation of highly water-soluble and weakly dissociated compounds formed by the reaction of most cations with aminopolycarboxylic acids (com-plexones). The titration endpoint is established using complexo-nometric and other indicators. In some cases, especially in the titration of turbid or strongly colored solutions, methods not involving indicators (instrumental methods), such as potenti-ometry, coulometry, conductometry, and photometric analysis, are used. Complexonometry is used to determine the content of minerals, products of metallurgy, and pharmaceuticals and the hardness of water.