ISO 4325:1990 (R2022)

A test portion of the sample is dissolved in water, the pH of the solution adjusted to 4.65 and the solution titrated against standard copper(II) sulphate solution using 1-(2-pyridylazo)-2-naphthol as indicator. Principally the method has been designed principally for determining ethylenediaminetetraacetic acid (EDTA) and it salts. Before determining other chelating agents, or determining ethylenediaminetetraacetic acid in the presence of other chelating agents, the applicability of the method should be confirmed.