Spectrophotometric determination of vanadium with salicylideneamino-4-hydroxybenzenesulfonic acid

Abstract

Spectrophotometric determination of vanadium with 3-N-salicylideneamino-4-hydroxybenzenesulfonic acid (SAPS). has been studied. SAPS easily reacts with vanadium in aqueous solution forming a yellow complex. The complex has an absorption maximum at 420 nm and a maximum absorbance is obtained in the pH range from 4.0 to 6.5. Beer's law holds over the range of 0100μg/25 ml of vanadium and the apparent molar absorption coefficient of the complex is 1.14×10⁴ l mol^-1 cm^-1. Trace amounts of aluminum(III), copper(II), iron(III) and molybdenum(VI) interfere with the determination but these interferences except molybdenum can be masked by adding thiourea and sodium fluoride. The established procedure is as follows. Transfer the sample solution containing up to 100μg of vanadium to a 25 ml volumetric flask. Add 5 ml of acetate buffer (pH 5.0) and 5 ml of 0.1% SAPS solution. Dilute to the mark with water and measure the absorbance at 420 nm using the reagent blank as reference. The proposed method is simple and rapid, then applied to the analysis of steel for vanadium. Large amounts of iron can be removed by ethyl ether extraction method in 6 N hydrochloric acid solution. Vanadium (0.10.3)% in iron and steel samples can be determined successfully.