Solvent Extraction Coupled On-Line to a Reversed Micellar Mediated Chemiluminescence Detection System for Trace-Level Determination of Atropine

Abstract

A fast and sensitive method for the determination of atropine, an alkaloid closely related to cocaine, is proposed. The principles of on-line ion-pair formation of alkaloid-metal complexes and liquid-liquid extraction are applied to the chemiluminescence determination of atropine. On mixing with a reversed micellar medium of cetyltrimethylammonium chloride in dichloromethane-cyclohexane (1:1 v/v)-water (0.3 M Na2CO3) containing luminol, the ion-pair complex of tetrachloroaurate(III) with atropinium produced an analytical chemiluminescence signal when it entered the reversed micellar water pool. Using the reverse-flow injection and chemical conditions optimized for atropine in aqueous samples, a detection limit of 1 ng/mL was achieved and a linear calibration graph was obtained with a wide dynamic range from 10 ng/mL to 100 micrograms/mL. The proposed method is simple and provides a good precision with a relative standard deviation (n = 6) of ca. 3% at the atropine concentration of 100 ng/mL. After a preliminary study involving the potential interference from species of organic, inorganic, and metallic nature, the method was applied to the determination of atropine in artificial urine samples and of atropine and scopolamine in pharmaceutical formulations.

Chemiluminescence from an Oxidation Reaction of Rhodamine B with Cerium(IV) in a Reversed Micellar Medium of Cetyltrimethylammonium Chloride in 1-Hexanol-Cyclohexane/Water

“…The CL signal increased with an increase in the Rw value. It has been observed that such a relationship between the CL intensity and Rw usually existed for the RMM-CL reaction of luminol, 3,4,6,8,[18][19][20]33,35,36 which may be facilitated by the generation of bulk-like water in the reversed micellar water pool at higher Rw. With the RB-Ce(IV) CL reaction, a similar effect of reversed micellar microenvironment seems to be the case.…”

“…3 In order to achieve enhanced sensitivity and improved selectivity in addition to other advantages, the CTAC reversed micellar medium has been successfully used to combine a solvent-extraction technique with the CL detection system based on the luminol oxidation in our previous studies. [15][16][17][18][19][20] After solvent extraction, it is possible to mix the extract directly with a reversed micellar solution of luminol dispersed in oil. Thus, we can avoid a relatively tedious procedure, like back extraction into the aqueous phase or evaporation of the solvent, which is required to use conventional aqueous solutions for CL measurements.…”

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.…”

Microheterogeneous systems of micelles and microemulsions as reaction media in chemiluminescent analysis

“…Until 1987, almost all of the micelleenhanced analytical procedures reported had utilized normal aqueous micelle systems. Consideration of so-called reversed micelles in CL measurements or [60], iron(III) [54,61], iron(II) [61], vanadium(IV) [55,62], atropine [63] and iodide and/or iodine [64].…”