SPECIATION OF IRON IN ENVIRONMENTAL WATER AND GEOLOGICAL SAMPLES BY KINETIC SPECTROPHOTOMETRY

A kinetic spectrophotometric approach is applied to the determination of iron oxidation states in environmental groundwater and silicate rock samples. The method is based on the rapid formation of iron(III)-Tiron complexes, while the oxidation of iron(II) is remarkably accelerated in the presence of Tiron. The increase of absorbance was followed at 560 nm and kinetic data were analyzed by non-linear least squares fitting. The proposed method does not require precise control of temperature, unlike most kinetic measurements.