Solid Phase Colorimetry of Trace Metal Ions Based on a Tristimulus Chromaticity Diagram. Simultaneous Determination of Iron(II) and Iron(III)

Solid phase colorimetry based on a tristimulus chromaticity diagram has been developed for the simultaneous determination of iron(II) and iron(III). 2-Nitroso-5-(N-propyl-N-sulfopropylamino)phenol (nitroso-PSAP) and finely divided anion exchange resins (chloride form) were used for the preconcentration of iron(II,III) complexes. The image of colour space for both iron complexes is represented by a chromaticity diagram and a calibration plane for iron(II) and iron(III) determinations is constructed at microgram levels.