ASTM International Standard Test Method for Ethylene Diamine Tetraacetate (EDTA) in Soaps or Synthetic Detergents ASTM D1767-89(2003)

This test method covers the determination of ethylene diamine tetraacetate (EDTA) in soaps and synthetic detergents. Throughout this test method EDTA represents the hydrated disodium salt containing 2 moles of H2O. In the chemical literature this is frequently abbreviated to Na2H2Y4·2H2O. Reagents to be used in the EDTA content determination include copper sulfate solution and PAN indicator solution. The procedure in EDTA determination is described as follows: A portion of the sample estimated to contain 1 % of EDTA disodium salt shall be weighed. The amount of the sample used depending upon the actual amount of EDTA present shall be varied. Then the sample shall be weighed into a 250-mL beaker, diluted to a certain volume with water, and adjusted the pH to approximately 5.0 by the addition of acetic acid. Four drops of the PAN indicator solution shall be added. The sample with CuSO4 solution shall be titrated until a transition in color from yellow to red occurs. Afterwards, the percentage of EDTA disodium salt in the sample shall be calculated.