The extraction of iron with di-(2-ethylhexyl)-orthophosphoric acid, and its direct determination with bathophenanthroline

Abstract

A simple, direct determination of iron(III) extracted from chloride solutions with di-(2-ethylhexyl)orthophosphoric acid is described. Iron in the organic phase is first reduced with ascorbic acid, bathophenanthroline and pyridine are then added and the colour developed measured at 533 nm. With this procedure, which involves extraction of the iron with a phase-volume ratio of 1:1, an improvement on the already appreciable selectivity of other bathophenanthroline procedures is obtained.

Extremely small amounts of iron can be determined with satisfactory precision when extraction is carried out with an inorganic-to-organic phase-volume ratio of 100:1. Results for the determination of iron in high-pressure boiler water are reported.