Infrared spectrometry for solid phase analysis: Corrosion rusts

For the quantitative analysis of iron oxides powders by infrared spectrometry, the importance of grinding, symmetry (three spectra per sample) and calibration are emphasized (five independent teams of two persons for nine phases, 60 spectra). Simple semi-quantitative problems (three FeOOH phases) are solved by a standard Cramer system. When maghemites are present, it is preferable to adjust the spectrum profile through a least squares method (425–587 cm−1 range). Contrary to Beer’s law, the Bouguer–Lambert formalism gives absolute values (μmoles Fe). Slope measurements are useful for the most difficult substance (Fe3O4).