Spectrophotometric determination of indium with 2-hydroxy-5-sulfoaniline-N-salicylidene.

Abstract

Indium reacts quantitatively with 2-hydroxy-5 sulfoaniline-N-salicylidene (HSS) to form a yellow complex at pH 7.07.2.The complex in an aqueous solution has an absorption maximum at 415 nm and the absorbance is stable for at least 24 h. The analytical procedure is as follows : One ml of a sample solution containing 150μg of indium (0.1 M hydrochloric acid solution) was diluted to about 15 ml with water. Five ml of 30 w/v % sodium acetate solution, an adequate amount of 0.1 M sodium hydroxide solution and 2 ml of 0.2 w/v % HSS solution in DMF were added. Then the mixture was diluted to 25 ml with water (the final pH : 7.1± 0.1). After 20 min, the absorbance was measured at 415 nm against the reagent blank. Beer's law was obeyed over the range of 150μg/25 ml of indium. The relative standard deviation (n = 5) on the absorbance for 30μg of indium was 0.5 %. The molar absorptivity was 3.16 × 104 1 mo1-1 cm-1. The molar ratio of indium to HSS in the complex was estimated to be 1 : 2 by the continuous variation method. Aluminum(III), gallium(III), scandium (III ), copper (II), and iron (III) interfered seriously. However, idium could be separated by extraction procedure with isopropylether from these interfering ions. By this method, trace amounts of indium mixed with high purity zinc could be successfully determined.