Analytical Sciences

Reversed Micellar Mediated Luminol ChemiluminescenceDetection of Iron(II, III) Combined with On-Line SolventExtraction Using 8-Quinolinol

Theingi KYAW, TerufumiFUJIWARA, Hidekazu INOUE, Yasuaki OKAMOTO and TakahiroKUMAMARU *

Department of Chemistry,Faculty of Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739, Japan

An enhancement of the chemiluminescence (CL) emission, observed when theiron(III) complex of 8-quinolinol (oxine),Fe(oxine)3, was mixed with areversed micellar solution of cetyltrimethylammonium chloride inchloroform-cyclohexane(6:5 v/v)-water (1.0 M NaOH) containing luminol and hydrogen peroxide, wasinvestigated in order to develop a methodfor iron(III) determination based on the direct coupling of on-line solventextraction with a reversed micellar-mediatedCL reaction in a reverse-flow injection system using a microporous Teflonmembrane filter for phase separation. In theCL process, uptake of the complex by reverse micelles and its subsequentdecomposition occurs easily, followed by aniron(III)-catalyzed luminol reaction. In the on-line process, iron(III) wasextracted from an aqueous solution intochloroform via complex formation with oxine. Upon mixing thereversed micellar luminol solution with the extractstream in a flow cell of a CL monitor, the produced CL signal was measured.A detection limit of 5 ng cm -3 Fe(III) and alinear calibration graph was obtained in the concentration range of 10 -500 ng cm -3 Fe(III). In a samplesolutioncontaining iron(II) and iron(III), total iron, Fe(II)+Fe(III), was measuredas the peak height in the presence of thehydrogen peroxide used to oxidize iron(II) to iron(III) prior to solventextraction, while only iron(III) could be determinedin the absence of hydrogen peroxide. (Keywords: Chemiluminescence, luminol, tris(8-quinolinolato)iron(III),reverse micelles, cetyltrimethylammoniumchloride, on-line solvent extraction)

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