1987 Volume 3 Issue 6 Pages 479-488
Ion-association reagents are widely used for analytical chemistry. The ion-associable cation or anion should be univalent, bulky and charge-dispersed. The reagents are classified by their shape: plane, sphere, chain and polymer types. The ion-associable cation and anion can combine with each other to form the ion-associate in water. This phenomenon has been used for gravimetric and volumetric analyses and for extraction-spectrophotometry of a trace component. Several examples of specific and sensitive extraction-spectrophotometries are illustrated. The polymer type reagent can react with the counter-charged poly-electrolyte to form a precipitate quantitatively, and it can be used for colloid titration. Metachromasy phenomenon is based on the formation of the ion-associate of colored ion-associable cation or anion with counter-charged colorless ion-association reagents to show distinguished color changes.
