An automated system was invented in 1964 and then a commercial colour analyzer was made available in 1974 by Technicon (Tarrytown, NY, USA). The basic mechanism involves the addition of mercury thiocyanate to a solution with an unknown concentration of chloride ions and iron as a reagent.
In 1964, an automated system was created, and in 1974, Technicon (Tarrytown, NY, USA) introduced a commercial colorimeter. The core procedure includes adding mercury thiocyanate to a solution with an unknown chloride ion concentration and iron as a reagent.