Extraction and Spectrophotometric Assay of Yttrium (III) with TOPO, Application to Water Samples and Alloys

An easy, accurate, selective and sensitive method for extraction and spectrophotometric determination of yttrium (III) in aqueous solution has been determined. The procedure is based on the extract of yttrium (III) with Trioctylphosphine oxide (TOPO) reagent from the aqueous medium followed reaction of extracted yttrium (III) in organic layer with alizarin red s (ARS) reagent at pH 4.9 to form a red carmine complex which has maximum absorption at 519 nm. Beer's law is obeyed over the concentration range 10-260 μg yttrium (III) /10 ml, (i. e., 1-26 ppm) with a determination coefficient of (0.991) and molar absorptivity of 0.53×10 4 l.mol -1.cm -1. The recoveries are obtained in the range of 98.7 - 100.01% and a relative standard deviation is better than ±2.33%. The method has been successfully applied to the determination of yttrium (III) in natural waters and magnesium alloys.