A reverse micelle is a droplet of water surrounded by surfactant molecules dispersed in an organic solvent of low polarity, where their polar groups are concentrated in the inner aqueous core of the aggregate, while their hydrophobic moieties extend into the bulk organic solvent. The water pool, formed by water molecules included in the core of reverse micelles, provides a unique and versatile reaction field, referred to as microreactors.1-4 The area with the most applications of reversed micellar media in spectroscopy is perhaps that of analytical bioluminescence or chemiluminescence (CL) measurements.3,4 It has been pointed out that the CL reaction occurs at the surfactant-water pool interface of the reverse micelles dispersed in the bulk organic solvent.3,5 Although a CL emission from luminol oxidation catalyzed by metal ions and metalcontaining ions is well known in conventional or usual aqueous solution 6,7 , in reversed micellar solutions this is rarely reported. [8][9][10][11] In our previous work 8 it was observed that the uptake of the iron(III) complex of 8-quinolinol (oxine), Fe(oxine) 3 , by a reverse micelle of cetyltrimethylammonium chloride (CTAC) into the water pool and its subsequent conversion into a reactive species, that is, iron(III) ion capable of catalyzing the CL reaction of luminol with hydrogen peroxide occur.Accomplished in many ways, the extraction of metal ions with a suitable organic solvent is effective in separation, and can be used in both micro and macro levels of concentration. When usual aqueous solutions are used in CL measurements after extraction, however, a relatively time-consuming procedure, like back extraction into an aqueous solution or evaporation of the solvent, is certainly needed before CL detection.
12On the other hand, the extract can be mixed directly with a reversed micellar solution of luminol dispersed in oil. We thus examined the development of a hybrid method based on the combination of the reversed micellar-mediated CL (RMM-CL) detection with solvent extraction for the determinations of iodine 13 , gold(III) 14,15 , and rhodium(III). 10 Furthermore, an online procedure for extraction via ion-pair formation followed by the RMM-CL detection was proposed for gold(III) determination using a reverse-flow injection (FI) system with a membrane filter for phase separation. 16 In this work, the luminol CL enhanced by the Fe(oxine) 3 complex in reverse micelles was investigated and on-line extraction through complex formation was combined with the RMM-CL reaction An enhancement of the chemiluminescence (CL) emission, observed when the iron(III) complex of 8-quinolinol (oxine), Fe(oxine)3, was mixed with a reversed micellar solution of cetyltrimethylammonium chloride in chloroform-cyclohexane (6:5 v/v)-water (1.0 M NaOH) containing luminol and hydrogen peroxide, was investigated in order to develop a method for iron(III) determination based on the direct coupling of on-line solvent extraction with a reversed micellar-mediated CL reaction in a reverse-flow injection ...