Highly sensitive oligosaccharide analysis in capillary electrophoresis using large-volume sample stacking with an electroosmotic flow pump

Abstract

To obtain high sensitivity in capillary electrophoresis of oligosaccharide without reducing the high resolution with an easy experimental procedure, large-volume sample stacking with an electroosmotic flow pump (LVSEP) was investigated. As a fundamental study, effect of the conductivity of a sample solution in LVSEP was examined. It was revealed that LVSEP was successfully carried out even in using a sample solution with the ionic strength of 150 μM and the conductivity ratio of 20, indicating a good applicability of LVSEP to the analysis of real samples containing salts. When glucose oligomer was analyzed as a model sample in LVSEP-capillary zone electrophoresis (CZE), all peaks were well resolved with decreasing only 5% of the peak-to-peak distance, which suggested 95% of the whole capillary could be used for the effective separation. In the analysis of maltoheptaose, a good calibration line with correlation coefficient of 0.9995 was obtained. The limit of detection was estimated as 2 pM, which was 500-fold lower than that in the conventional CZE. N-linked glycans released from three glycoproteins, bovine ribonuclease B, bovine fetuin, and human α(1)-acid glycoprotein were also analyzed by LVSEP-CZE. By the sample purification with a gel filtration column, further sample dilution to reduce the sample conductivity for LVSEP was not needed. All glycan samples were well concentrated and separated with up to a 770-fold sensitivity increase. The run-to-run repeatabilities of the migration time, peak height, and peak area were good with relative standard deviations of 0.1-1.3%, 1.2-1.7%, and 2.8-4.9%, respectively.

On-line Sample Preconcentration by Large-volume Sample Stacking with an Electroosmotic Flow Pump (LVSEP) in Microscale Electrophoresis

“…We applied this technique to the CE analysis of oligosaccharides. 42 In the LVSEP-CZE analysis of oligosaccharides, up to a 2500-fold sensitivity improvement and good resolution utilizing a long effective separation length with 95% of the total length were achieved. Furthermore, we found that a conductivity ratio (σBGS/σSM) larger than 20 and an electrolyte concentration of the sample less than 0.15 mM were needed to obtain the LVSEP effect.…”

Recent Studies on Online Sample Preconcentration Methods inCapillary Electrophoresis Coupled with Mass Spectrometry

“…To achieve truly practical analysis, thus, smart construction of whole analytical system including sample collection and pretreatment is of more importance. For example, LVSS provides high sensitivity and resolution via a simple procedure (full-capillary injection and constant voltage application) [35][36][37][38][39][40], where the optimization process can be minimized. It is suitable for the total system development and therefore, further deeper understanding of OSP methods are required.…”

“…After the sample concentration, the focused analytes are separated by CZE in the BGE. As only tens-fold sensitivity increase is usually available due to limited injection volume, similar techniques such as field-amplified sample injection (FASI) and large-volume sample stacking (LVSS) have been developed to increase the loadable volume [35][36][37][38][39][40].…”

Application of Online Preconcentration Affinity Capillary Electrophoresis Method to Glycans Labeled with 8-Aminonaphthalene-1,3,6-trisulfonic Acid Using Blue Light Emitting Diode-induced Fluorescence Detection

“…[13][14][15][16] This exhibits efficient preconcentration and separation performance and the sample components are stacked at the sample/buffer boundary for a long time. Therefore, by injecting lectin from the anodic end as a short plug, followed by injection of sample solution to the entire capillary, anionic derivatives of oligosaccharides are continuously moved and stacked in the lectin plug until the completion of preconcentration.…”