Electrokinetic supercharging for highly efficient peptide preconcentration in capillary zone electrophoresis

Abstract

Electrokinetic supercharging has been integrated in CZE for the development of a highly sensitive methodology for protein tryptic digest analysis. A careful choice of the experimental conditions led to sensitivity enhancement factors between 1000 and 10 000 whilst maintaining a satisfactory resolution. Peptides in the low nanomolar concentration range have been detected despite the use of the poorly sensitive UV absorbance detection mode. The buffer system used in this study is fully suitable for coupling CE to MS.

Electrokinetic supercharging focusing in capillary zone electrophoresis of weakly ionizable analytes in environmental and biological samples

“…Generally, this low-conductivity plug provides a higher electrical field at the beginning of the capillary and ensures the fast migration of the analytes across this plug. In this way, it is possible to improve the sample stacking efficiency between this zone and the BGE zone [12,38,39]. Additionally, if there are salts present in the matrix, this plug helps to maintain reproducibility [40].…”

“…This combination was first introduced by Hirokawa et al [10] and named electrokinetic supercharging (EKS). In that work, a mixture of 18 inorganic cations was analyzed with detection limits of 0.3 mg/L when the sample was injected by EKI at 20 kV for 150 s. Following the successful introduction of this new preconcentration strategy, EKS has been applied for the analysis of other kinds of compounds in different matrices [11][12][13][14]. For example, Busnel et al [11,12] used this preconcentration technique to analyze peptides in biological samples.…”

Advances in the theory and application of MEEKC

“…Reproduced with permission from [7]. [14], dynamic pH junction [15], sweeping and stacking with reverse migrating pseudostationary phase (SRMP) [16] as well as a combination of these techniques. Sample stacking is the result of sample ions moving across a boundary, which is formed inside the capillary between the sample and separation zone.…”

Sample stacking in CZE using dynamic thermal junctions I. Analytes with low dpKa/dT crossing a single thermally induced pH junction in a BGE with high dpH/dT

“…Several methods of sample stacking in CE have been proposed, studied, and improved during the last two decades [1][2][3][4][5][6][7][8][9]. Most of these methods are based on simple principles, but are sometimes very laborious in practice.…”