Before revision: Calconcarboxylic acid (IUPAC name 3-hydroxy-4-[(2-hydroxy-4-sulfonaphthalen-1-yl)diazenyl]naphthalene-2-carboxylic acid; commonly called Patton and Reeder's Indicator) is an azo dye which is used as an indicator for complexometric titrations of calcium with ethylenediaminetetraacetic acid (EDTA) in the presence of magnesium.
After revision: Calconcarboxylic acid (IUPAC name 3-hydroxy-4-[(2-hydroxy-4-sulfonaphthalen-1-yl)diazenyl]naphthalene-2-carboxylic acid; commonly called Patton and Reeder's Indicator) is an azo dye that is used as an indicator for complexometric titrations of calcium with ethylenediaminetetraacetic acid (EDTA) in the presence of magnesium.