COMBINATION OF SOLID-PHASE EXTRACTION AND FLAME ATOMIC-ABSORPTION SPECTROMETRY FOR DIFFERENTIATED ANALYSIS OF LABILE IRON(II) AND IRON(III)SPECIES

The labile iron(II) and iron(III) species are complexed directly in th e sample solution with 1,10 phenanthroline and ferron (8-hydroxy-7-iod oquinoline-5-sulfonic acid), respectively. The complexes thus formed a re mutually adsorbed and separated by solid phase extraction. The dire ct determination of iron(III) and iron(II) species with flame atomic a bsorption spectrometry (FAAS) follows the elution of the iron(III)-fer ron complex adsorbed by an anion-exchange and an iron(II)-phenanthroli ne complex adsorbed by a non-polar RP-18 phase. In the case of indirec t determination, the iron(II)-phenanthroline complex that passes throu gh the anion-exchange phase, is measured, and the content of iron(III) is calculated by the difference of the iron(II) and the total iron co ntent. A direct determination with this method has been applied to the iron species analysis in wine samples and the results are compared wi th those obtained for the determination with adsorptive stripping volt ammetry (ASV) as reference method.