Spectrophotometric determination of indium with xylenol orange

Abstract

A method is described f or the spectrophotometric determination of indium with Xylenol Orange. The sample solution containing 5~80 μg of indium is transfered to a 25 ml volumetric flask. Ammonium bifluoride is added to mask small amounts of aluminum, thorium and zirconium. o-Phenanthroline is then added to mask copper, cobalt and nickel. The pH is adjusted to 3~4. Ten ml of buffer solution (pH 3.3~3.6) and then Xylenol Orange are added. After diluting to the mark and allowing to stand for 10 minutes the absorbance is measured in a 10 mm cell at 530 mμ, using the reagent blank as the reference. Beer's law is obeyed and the molar absorbancy index is 1.9×104. According to the continuous variation method and mole ratio method, the composition of the complex corresponds to In-XO is 1: 1, where XO is Xylenol Orange. Five mg of uranium (VI), 1 mg of cadmium and chromium (III) do not interfere. © 1963, The Japan Society for Analytical Chemistry. All rights reserved.