Reversed Micellar Mediated Luminol Chemiluminescence Detection of Iron(II, III) Combined with On-Line Solvent Extraction Using 8-Quinolinol

Abstract

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 ...

Acid-Base Behavior of Rhodamine B in a Reversed Micellar Medium of Cetyltrimethylammonium Chloride in 1-Hexanol-Cyclohexane/Water

“…4,5 Using cetyltrimethylammonium chloride (CTAC) reverse micelles as micro-reactors in CL analysis, we have developed a flow-injection method based on a reversed micellar-mediated CL detection following solvent extraction. [6][7][8][9] In our previous studies concerning a luminol CL reaction with metal complexes in the CTAC reversed micellar solution, 10,11 it has been noted that the dissociation of metal complexes occurs at the reversed micellar interface, and that the released metal ions subsequently catalyze the CL reaction in the reversed micellar aqueous phase immediately after metal uptake by the reverse micelle into the water pool. In the uptake process, the reversed micellar interface has been regarded as being significant.…”

Simultaneous Determination of Iron(II) and Iron(III) by Micellar Electrokinetic Chromatography Using an Off-line Selective Complexing Reaction

“…The proposed method had a sensitivity enhancement of about 70-fold greater than that of UV/CE by Naujialis et al 13 (for Fe(II)), about 2200-fold greater than that of the chemiluminescence detection/flow injection by Kyaw et al 14 (for Fe(III)). Moreover, the proposed method was compared with other highly sensitive analyses, such as AAS 15 and XRF.…”

Application of Flow-Injection Spectrophotometry to Pharmaceutical and Biomedical Analyses

“…Thus, by combining the pretreatment (digestion, preconcentration, sample clean-up, and solvent-solvent extraction, etc.) with on-line sample introduction, the FIA system becomes a very efficient and advantageous technique [52][53][54][55][56][57].…”