ABSTRACT

A simple ion chromatographic technique is described for the routine determination of the Fe₂O₃/FeO ratio in geological samples. The iron species were eluted using pyridine-2, 6-dicarboxylic acid (PDCA), and photometrically detected at 520 nm as mono- and divalent complexes using a wavelength detector. An analysis is completed in approximately 10 minutes and, unlike commonly applied titrimetric methods, does not require an independent measurement of the total iron content of the sample. The technique is applicable to sample sizes of 25-50 mg, enabling the analysis of fragments of quench glass and individual large mineral grains. Results from the analysis of 7 international standard reference materials of widely differing Fe₂O₃/FeO ratios show a high degree of reproducibility (2σ=±0.02 in Fe₂O₃/FeO ratio) and are, with one exception, in close agreement with recommended published values.