Factors affecting the determination of iron species in the presence of ferric iron

The high concentration Fe³⁺ in sample had interference on the determination of iron species by spectrophotometric method in which 1,10-phenanthroline was used to as a chromogenic agent. The F⁻ could mask absolutely the effect of Fe³⁺ when F⁻/Fe³⁺ molar concentration ratio was 13.3. The temperature or light did not affect the masking action of F⁻. Low temperature and dark conditions favored the stability of chromophoric complex. This method is suitable for the measure of iron species where the concentration of Fe³⁺ is far more than that of Fe²⁺ in samples.