Electrokinetic supercharging preconcentration and microchip gel electrophoretic separation of sodium dodecyl sulfate‐protein complexes

Abstract

A microchip gel electrophoresis (MCGE) method with electrokinetic supercharging (EKS, electrokinetic injection with transient isotachophoresis) on a single channel chip was developed for high-sensitive detection of a standard mixture of six proteins (phosphorylase b, albumin, ovalbumin, carbonic anhydrase, trypsin inhibitor, and alpha-lactalbumin) in the form of sodium dodecyl sulfate (SDS) complexes. An average lower limit of detectable concentration (LLDC) achieved using UV detection at 214 nm was 0.27 microg/mL that is 30 times lower than that of conventional MCGE on a cross geometry chip. The calibration curves for molecular weight and concentration of SDS-protein complexes suggested that the present EKS-MCGE method had a better linear dynamic range and benefited future applications for qualitative and quantitative analysis of unknown protein samples. It was found that an excessive amount of unbound SDS in the sample deteriorated the preconcentration effect and resolution. The developed method appears greatly promising for high-speed and high sensitive analysis of SDS-proteins by MCGE.

Highly sensitive double‐fluorescent dye staining on microchip electrophoresis for analysis of milk proteins

“…The sizing and quantitation data of these milk proteins are shown in Table 2. Except for casein aggregations, the sizing accuracy was within 3.5%, which was regarded as good in ME [4][5][6][7][8][9][10] and the quantitation results were also good compared to those of another report [19]. Consequently, these results suggested that our staining method was promising for analysis of real biological proteins.…”

“…To enhance the sensitivity, alternatives such as LIF detection instead of UV detection [7], on-line preconcentration [8], porous membrane [9] and a special detection method like refractive index detection [10] have been examined. However, they needed custom-made instruments and were labor intensive, and so have not been put to practical use.…”

Electrokinetic supercharging for highly efficient peptide preconcentration in capillary zone electrophoresis

“…For example Quirino and Terabe [20] have demonstrated that SEFs as high as several hundreds of thousands are reachable if FESI is used under sweeping condition. Also, Hirokawa and co-workers [21][22][23] have introduced few years ago the electrokinetic supercharging (EKS) methodology. In EKS, analytes are introduced into the separation capillary with an electrokinetic injection under conditions that are suitable for isotachophoretic stacking.…”

High‐sensitive protein analysis by FESI‐CE‐MALDI‐MS

“…For example, the acido-basicity or hydrophobicity characteristics of the considered analytes are used in the dynamic pH junction [14][15][16][17] and sweeping [18] [19,20]. It combines the strengths of electrokinetic injection and those of t-ITP and has so far been applied to small ions [21], DNA strands [22], SDS denaturized proteins [23] as well as peptides [24].…”