Spectrophotometric determination of iron in nickel-base alloys with 1, 10-phenanthroline or bathophenanthroline

Abstract

The spectrophotometric method was studied for determining about 0.1% of iron in nickel-base alloys with 1, 10-phenanthroline or bathophenanthroline (4, 7-diphenyl-1, 10-phenanthroline). Iron was previously separated by methyl isobutyl ketone (MIBK) extraction from 6M hydrochloric acid solution. When the sample contained a few percent of molybdenum, low values for iron were obtained. This was prevented by adding large amounts of hydroxylamine hydrochloride and 1, 10-phenanthroline. Satisfactory results were obtained for (0.10.2)g of sample by adding 5 ml of 100 g/l hydroxylamine hydrochloride solution and 20 ml of 2 g/l phenanthroline solution tn 100 ml of final solution. The apparent molar absorptivity was 1.1×104 1 mol-1 cm-1 at 510 nm.In place of 1, 10-phenanthroline, bathophenanthroline serves the purpose. After separation by MIBK extraction, iron (III) was reduced with ascorbic acid, and the iron (II)-bathophenanthroline-perchlorate complex was extracted into chloroform. The absorbance of the organic phase was measured at 532nm. The apparent molar absorptivity at this wavelength was 2.2×104 l mol-1 cm-1. The results obtained by the bathophenanthroline method agreed quite well with those obtained by 1, 10-phenanthroline method.