Application of the H-point standard addition method to the speciation of Fe(II) and Fe(III) with chromogenic mixed reagents

Simultaneous determination of Fe(TI) and Fe(III) or selective determination of each oxidation state of iron in the presence of the other one by H-poin t standard addition method (HPSAM) is described. Mixed reagents of 1,10-phe nanthroline and salicylic acid was used as a selective chromogenic system f or speciation of Fe(II) and Fe(III). It was shown that with appropriate sel ection of wavelength pairs, both Fe(II) and Fe(III) can be considered as an alyte. The results showed that Fe(II) and Fe(III) can be determined simulta neously with the concentration ratios of Fe(II) to Fe(III) varying from 10: 1 to 1:20 in the mixed sample. The accuracy and precision of the method are all satisfactory. (C) 2001 Elsevier Science B.V. All rights reserved.