Spectrophotometric Assay of Yttrium(III) with Alizarin Red S in the Presence of Cetyltrimethylammonium Bromide -Application to Water Samples


A simple, accurate and sensitive procedure for spectrophotometric determination of yttrium (III) in aqueous solution has been developed. The method is based on the reaction of yttrium (III) with alizarin red S (ARS) reagent in the presence of cetyltrimethylammonium bromide (CTAB) and triton-X-100 surfactants at pH 4.7 to form a red carmine complex which has maximum absorption at 520 nm. Beer's law is obeyed over the concentration range 2.5-75 µg yttrium (III) /20 ml, (i.e. ,0.125-3.73 ppm) with a determination coefficient of (0.9954) and molar absorptivity of 1.16×104 l.mol-1.cm-1. The limit of detection (LOD) and the limit of quantification (LOQ) are 0.1009 and 0.323 g.mL-1, respectively. Under optimum conditions, the stoichiometry of the reaction between yttrium (III), alizarin red S and CTAB is found to be 1:2:2, respectively. The recoveries are obtained in the range of 98.07 - 100.63% and the relative standard deviation is better than ±2.33%. The method has been successfully applied to the determination of yttrium(III) in natural waters