LVSEP Analysis of Cationic Analytes in Non-Aqueous Capillary Electrophoresis

Abstract

To achieve highly sensitive analyses of cationic analytes with simple experimental procedures in non-aqueous capillary electrophoresis (NACE), large-volume sample stacking with an electroosmotic flow pump (LVSEP) was performed in dynamically polymer coated capillaries. As the dynamic coating polymers, cationic polybrene (PB), and neutral polymer, (hydroxypropyl)methyl cellulose (HPMC), were employed in methanolic media to reverse and suppress the electroosmotic flow. In the analysis of cationic amines, good enrichments were attained with the sensitive enhancement factor (SEF) of 70 and 687 for benzylamine and 1-(1-naphthyl)ethylamine, respectively, with a methanolic running solution containing 1.0% HPMC and 0.5% PB. In the NACE-LVSEP analysis of Ru(bpy) 3 2+ and Ru(phen) 3 2+ , furthermore, the values of SEF were almost 40 with almost no-loss of the resolution.

Practical sample pretreatment techniques coupled with capillary electrophoresis for real samples in complex matrices

“…To stack a long plug of sample to achieve high preconcentration without losing the separation quality, the sample matrix must be removed before the separation step. The matrix removal can be carried out either via polarity switching [37] or EOF pumping in an automatic manner [38]. These techniques called as large volume sample stacking (LVSS) can provide EFs of up to several hundreds.…”

Nonaqueous capillary gel electrophoretic analysis of metal nanoclusters in polymeric–DMSO–Li+ systems

“…As reported previously, PVA-N-methyl-2-pyrrolidone (NMP)-Li salt mixtures form viscous organogel electrolytes [19]. For the application of organogel systems to NACGE, at first, common organic solvents used in NACE [24] were tested. In PVA-methanol-Li + system, a stable baseline was obtained in the electropherograms, but a sufficient solubility of PVA was not obtained.…”

LVSEP Analysis of Cationic Analytes in Cationic Polymer-Coating Microchannel Prepared by Vacuum-Drying Method

“…To overcome the sensitivity problem, various on-line sample preconcentration techniques, including stacking [4][5][6], sweeping [7,8], selective sweeping [9][10][11], dynamic pH junction [12], transient isotachophoresis [13][14][15] and their modified techniques [16][17][18][19][20], have been developed in capillary electrophoresis (CE) and MCE. Among these techniques, large-volume sample stacking with an electroosmotic flow (EOF) pump (LVSEP) has several unique characteristics, e.g., efficient enrichments by a whole column sample-injection, simple experimental procedures based on a voltage application without polarity switching, and high resolutions according to the movement of the stacked analytes zone from the column inlet to the outlet [21][22][23][24][25][26][27][28][29][30]. However, the LVSEP technique has been mainly applied to the analyses of anionic compounds, i.e., the applications to cations have been limited since a reversal EOF is required.…”

“…At first, the microchannel is coated with cationic polymers to obtain weakly and positively-charged surface (Fig. 1a) [21,26]. A low-ionic strength (I) sample solution containing cationic analytes is fully injected into the channel (Fig.…”