将试样的一部分溶解在水中，将溶液的pH值调节至4.65，并使用1-（2-吡啶偶氮）-2-萘酚作为指示剂，用标准硫酸铜（II）溶液滴定溶液。该方法主要用于测定乙二胺四乙酸（EDTA）及其盐类。在测定其他螯合剂或在存在其他螯合剂的情况下测定乙二胺四乙酸之前，应确认该方法的适用性。

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.