Sample stacking by field‐amplified sample injection and sweeping for simultaneous analysis of acidic and basic components in clinic application

Abstract

In this study, online sample concentration method, which coupled field‐amplified sample injection (FASI) and sweeping technology with micellar electrokinetic chromatography (MEKC), was used to detect and analyze acidic and basic components in a single run. In order to concentrate the acidic and basic components simultaneously in a single run sweeping step, a combination of successive anion‐ and cation‐selective injections were used. Before sample loading, a rinse buffer containing 50 mM Tris buffer (pH 3) with 41% MeOH and 0.1% polyethylene oxide (PEO) was injected in order to suppress the electroosmotic flow (EOF). Sample loading of anionic components was achieved by electrokinetic injection at a negative voltage of −2.5 kV for 80 s, and then the cationic components were injected at a positive voltage of +5 kV for 120 s. Finally, sweeping with SDS micelles from the separation buffer (25 mM Tris buffer with 60 mM SDS, pH 3) was performed at a negative voltage of −20 kV. This capillary electrophoretic methodology was applied to the quantification of acidic and basic drugs in commercial tablets and in plasma samples. The precision and accuracy of the proposed method at different concentrations ranging from high, medium, to low were evaluated on spiked plasma samples. The intra and interday precision and accuracy values at three concentrations were all below 6.1%. The method was also successfully applied to monitor the tested drugs in the plasma of nine elderly cardiovascular and/or Alzheimer's disease patients after oral administration of the commercial products.

Contemporary sample stacking in analytical electrophoresis

“…An online sample concentration method coupling FASI and sweeping with MEKC was used by Wei et al. to detect and analyze acidic and basic components. Simultaneous concentration of acidic and basic components in a single sweeping step was reached by combination of successive anion‐ and cation‐selective injections.…”

Recent contributions for improving sensitivity in chiral CE

“…Even, Wei et al. combined a successive CSEI‐ASEI with sweeping to analyze both acidic and basic components in a single run. However, to the best of our knowledge, there have been no studies reporting the use of ASEI‐sweeping or CSEI‐ASEI‐sweeping to achieve enantioseparations.…”

Simultaneous separation of cations and anions in capillary electrophoresis – recent applications

“…One of the chemical ways to modify ion mobilities is to use complexing agents than can form anionic complexes with transition metal cations, allowing their detection alongside native anions in the sample [2]. Another way is to use cationic micelles to sweep anionic compounds towards the detector end of the capillary [3]. In counter electroosmotic flow (EOF) mode CE, an increase in the pH of the background electrolyte is created, which increases the magnitude of the EOF to such an extent, that the migration direction of slow anions is reversed and they can be detected alongside analytes of opposite charge [4].…”