Fast Spectrophotometric Determination Of Fe3+ And Fe2+ In Commercial Glass

Total iron and Fe0/Fe20 ratio in the glass can be otbained by spectrophtometry. A fourth derivative calculation and the conventional procedure are respectively applied for the determination of Fe3+ and Fe2+ concentrations. The shape of the fourth derivative in the 360-400nm range recorded with the same spectrophotometer was similar for analysed samples with different Fe203 concentrations but with the same glass system (soda-lime, borosilicate). By a simple linear regression the peak height of the fourth derivative can be correlated with the known Fe3+. In the case of flat polished samples the sole spectrophotometric measurement allows total iron and Fe0/Fe203tot ratio to be obtained with an accuracy comparable to wet chemical analysis.