This method describes how to determine the iron content of boiler feed water. Iron can cause surface deposits to develop.
Boiler feed water for use in the production of beer and other foods
Fe(III) ions form a complex with sulfosalicylic acid, which is red in an acidic solution and yellow in an alkaline solution. Since Fe(II) ions are oxidized in an alkaline solution, they are detected as well. In this way, the value for total iron can be measured.