On-Capillary Sample Preconcentration Incorporated in Chiral Capillary Electrophoresis

Abstract

The on-capillary sample enrichment technique was developed to improve the sensitivity of UV-detection in capillary electrophoresis (CE). The enrichment was achieved in a preconcentration zone (zone length 2 mm) filled with the packing material used for HPLC, which is fixed by an inner frit near to the inlet of the capillary. The feasibility of this technique was demonstrated by chiral separation of a low concentration of verapamil (VER, a calcium channel blocker) enantiomers. The preconcentration procedure involves initial conditioning of the capillary, hydrodynamic sample introduction, washing of adsorbed VER, and its transfer to the capillary. Enriched VER was separated into enantiomers using a chiral selector (25 mM trimethyl-a-CD) dissolved in the run buffer (pH 2.5). The detection limit was 5 nM, about 200-times lower than that without preconcentration.The detection response indicated good linearity against the concentration of VER over the 10 -100 nM range for each enantiomer (r>0.999). The present CE system was applied to determine the unbound concentration of VER enantiomers in human plasma after ultrafiltration.

In‐line solid‐phase extraction preconcentration in capillary electrophoresis‐tandem mass spectrometry for the multiresidue detection of quinolones in meat by pressurized liquid extraction

“…Two types of applications have been reported using AC: characterization of metabolite and biopolymer mixtures [7][8][9][10][11] and determination of small molecules such as hypogly-cemic drugs [12], oxprenolol [13], verapamil [14], doxepin [15], terbutaline [16], ceftiofur [2], chlorophenols [17], and 3-nitrotyrosine [6]. Quantification was just attempted in case of small molecules and it was limited to only one or two compounds, using in all cases UV-Vis detection.…”

Quantitative analysis of pharmaceutically active peptides using on-capillary analyte preconcentration transient isotachophoresis

“…Direct injection is perhaps possible for analytes present in biofluids, like aqueous humor [33], cerebrospinal fluid, tears [34], or urine [35,36], but in the case of plasma this does not seem possible. For this reason off-line ultrafiltration [37] or off-line solid-phase extraction should be employed. Our results with solid-phase extraction are promising but more research has to be done to overcome the problems with robustness.…”

The use of selective adsorbents in capillary electrophoresis-mass spectrometry for analyte preconcentration and microreactions: A powerful three-dimensional tool for multiple chemical and biological applications

“…Several applications employing immobilized affinity ligands with nonspecific functions have also been reported [152,154,155,158,161,[166][167][168][169][170][171][172][173][174][175]. Some of these applications have been targeted for peptide mapping studies, utilizing peptides derived from protein digestion [167][168][169], others are related to peptide purification and characterization from peptides generated by a synthetic chemical process [191], and yielding chemical by-products of the reaction.…”