Capillary Electrophoresis of Inorganic Anions in Nonaqueous Media with Electrochemical and Indirect UV Detection

Abstract

Methanol and dimethylformamide were evaluated for the separation of a series of inorganic anions. As these solvents were added to an aqueous electrolyte, the electroosmotic flow went through a minimum at 70-80% (v/ v) organic solvent and then increased as the composition approached that of the pure solvent Reproducibility of electroosmotic flow was good (%RSD = 1.1 for dimethylformamide), and Joule heating was not as important as in water systems. The effect of electrolyte concentration on electroosmotic flow was similar to that expected for aqueous solutions, but significant differences in separation selectivity were observed, with many ions showing reversed separation order compared to aqueous systems.

Integration of Flow Injection Analysis and Zeptomole-Level Detection of the Fe(II)-o-Phenanthroline Complex

“…First, the electroosmotic driving force can be applied only to aqueous solutions or to a few polar solvents. [19][20][21] Moreover, applying an electric field causes spatial inhomogenization of the components, owing to a difference in the mobility; this could lead to a spatial change in the sample composition during transportation under a high electric field, although this effect is necessary for electrophoresis analyses. There are usually multi-components in a sample solution, and each component has a characteristic mobility.…”

Detecção eletroquímica em eletroforese capilar

“…A ED também é bastante apropriada em separações eletroforéticas em meio não-aquoso (NACE), uma vez que a maioria dos solventes utilizados absorve fortemente na região do UV, o que dificulta as medidas fotométricas. Com efeito, AD tem sido aplicada com sucesso em técnicas de NACE [202][203][204][205][206][207][208] . Separações quirais são de grande interesse em análises clínicas e na indústria farmacêutica e, nestes casos, a AD também tem estado presente 62,209,210 .…”

Électrophorèse capillaire en milieu non aqueux

“…C'est d'ailleurs une des raisons pour lesquelles le méthanol et l'acétonitrile sont les solvants les plus utilisés en milieu non aqueux. Il est cependant à signaler que d'autres modes de détection peuvent être envisagés, la détection UV indirecte [13,14], la détection fluorimétrique indirecte induite par LASER [15,16], la détection électrochimique qui est bien adaptée aux solvants dipolaires aprotiques comme le dimethylformamide, le dimethylsulfoxyde et l'acétonitrile [17][18][19] ou encore le couplage CE/MS qui nécessite des solvants volatils tels que le méthanol ou l'acétonitrile [4,[20][21][22]. Ainsi dans l'étude du métabolisme du tamoxifène en électrophorèse capillaire couplée à la spectrométrie de masse (ESI), il a été constaté une meilleure résolution et une sensibilité plus grande en milieu organique par rapport au milieu aqueux [22].…”

“…Dans certains cas, il a été signalé une amélioration au niveau de la résolution [28,31] ou encore de l'efficacité [19]. Mais l'intérêt essentiel d'introduire un co-solvant organique dans la veine liquide en électrophorèse capillaire est d'engendrer une modification de la sélectivité favorable à la séparation des constituants d'un mélange [19], qui se traduit même parfois par une modification de l'ordre d'élution [29].…”