Determination of iron in water samples

Abstract

In this method the catalytic effect of iron (III) has been achieved by the reaction of 9,10-diaminoanthracene and p-phenylenediamine with N-mono-methylaniline instead of N,N-dimethylaniline. In the presence of hydrogen peroxide and acetic acid as an activator, the produced colour is measured. at 765 and 730 nm within 20 min. The concentration ranges are 2.236 to 22.360, 8.96 to 89.6 μg per liter (for Fe II, III respectively) and molar absorptivities are 9.41 × 106, 4.73 × 105 L mol’1 cm-1 for 9,10-diaminoanthracene and p-phenylenediamine respectively. At the same time, 8-hydroxyquinoline has been used for spectrophotometric determination of ferric ions at 760 nm in acetate buffer pH 4.7. Beer's law is obeyed in the concentration range 0.0450 to 0.447 mg ferric ions per liter. Indirect coulometric technique has been adopted as a new method to determine iron. It is well known that ferric ions form a stable complex with 8-hydroxyquinoline in acetate buffer pH 4.7. The excess oxine can be determined coulometrically at 40 milliamp. constant coulometric current. Bromination is achieved by the generation of bromine from N-bromosuccinimide at a platinum anode. © 1995, Walter de Gruyter. All rights reserved.