Kinetic- and catalytic-spectrophotometric determination of iron by pyrogallolphthalein and potassium perdisulphate in non-ionic surfactant micellar medium

Abstract

A simple and highly sensitive spectrophotometric determination of iron with pyrogallolphthalein in a micellar medium of non-ionic surfactant is proposed. This method is based on the kinetic-catalytic action of iron(III) upon the decomposition reaction between pyrogallolphthalein and potassium perdisulphate at pH 2.4–2.9 in the presence of Triton X 100 as a non-ionic surfactant. The calibration graph is linear over the range 10–600 ng iron(III) per 10 ml in spectrophotometry (apparent molar absorption coefficient for decomposition was 1.25×10−6 l per mole per cm at 385 nm). The method was applied to assay and recovery tests for artificial waste water with satisfactory results (recovery 97.6%–103.5%).