Simple and rapid method for the determination of iron in water

Abstract

A simple and rapid method has been developed for the determination of iron in water by colorimetry using disodium bathophenanthroline disulfonate as a color development agent. It was found that suspended iron in water such as ferric hydroxide and ferric oxide could be dissolved and ionized with oxalic acid rapidly. To a transparent cylindric measurement vessel with 25 ml volume, a 20 ml of water sample and 20 mg of oxalic acid were added, and the vessel was vigorously shaken for a minute. Then, a mixture of L-ascorbic acid, disodium bathophenanthroline disulfonate and a blue dye were added and the vessel was shaken for 2 min. The determination of iron of 0.05~0.5 ppm was easily carried out by comparing the color of sample solution to a standard color scale. In the presence of the blue dye, color of the sample solution turns from blue to purple with an increase of iron. The determination of iron was interfered with Cu(II) and a large amount of Ca(II), however the addition of EDTA after color development could eliminate these interferences. The results of the determination of iron in water by the proposed method agreed well with those by AAS. © 1987, The Japan Society for Analytical Chemistry. All rights reserved.