Simultaneous separation of basic and acidic proteins using 1‐butyl‐3‐methylimidazolium‐based ion liquid as dynamic coating and background electrolyte in capillary electrophoresis

Abstract

1-Butyl-3-methylimidazolium tetrafluoroborate ionic liquids (1B-3MI-TFB ILs) were employed as a coating material and BGE in CE for simultaneous separation of basic and acidic proteins such as lysozyme, cytochrome C, ribonuclease A, albumin, and alpha-lactalbumin. 1B-3MI-TFB ILs effectively reversed the surface charges on the capillary inner surface, preventing the adsorption of positively charged proteins onto the silica surface, as well as associated with proteins, thus benefiting the separation efficiencies and reproducibility. Consequently, simultaneous baseline separation of five proteins was achieved within 14 min by using 10 mM of 1B-3MI-TFB ILs as dynamic coating and the only running electrolyte at the voltage of +20 kV. The proposed coating technique is simple, less time-consuming, reproducible, and also stable enough for proteins separation without the need of additives. Symmetrical peaks with efficiencies up to 670,000 plates/m were obtained. Recoveries of proteins with RSD (for migration times) of 0.23-0.42% (run-to-run) and 2.5-3.8% (day-to-day) were achieved, respectively. The applicability of the proposed method in proteins separation was evaluated by the separation of egg white samples.

Separation of acidic and basic proteins by CE with CTAB additive and its applications in peptide and protein profiling

“…However, their preparation is somewhat complicated. Ionic liquids have also shown their potentials in protein separation as coating materials or background electrolytes [25]. In particular, CTAB/chloride (CTAB/C), a cationic surfactant, has been used as buffer additive for CE of proteins [26][27][28][29].…”

Recent advances in column coatings for capillary electrophoresis of proteins

“…Applying ionic liquids (IL) as dynamic coating agents showed several advantages in capillary electrophoresis separations such as high solubility, heat stability, good electrical conductivity, adequate influence on EOF and efficient adsorption onto the capillary wall [29]. Wu et al [20] employed 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid as dynamic coating material for the separation of basic and acidic proteins. As a matter of fact, ionic liquids assist better in the separation of proteins with reasonable background current compared to other common electrolytes.…”

Application of Ionic Liquids in Liquid Chromatography

“…ILs as dynamic coating materials were used for separation of different groups of compounds. For instance, dimethyldinonylammonium bromide was used for determination of carboxylates as copper complexes (Laamanen et al,2005), 1-alkyl-3-methylimidazoliumbased ionic liquids were used as the running electrolytes for separation of acidic and basic proteins Wu et al, 2008) and flavone derivatives (Qi et al,2006), nicotinic, isonicotinic and picolinic acids (Marszałł et al, 2006 b), monocationic and dicationic phosphonium-based ILs were tested for separation of inorganic and small organic anions (Krizek et al,2009). Dicationic ion paring reagent (N,N'-dibutyl 1,1′-pentylenedipyrrolidinium) was applied for determination of several anions in the positive mode using CE-ESI-MS method achieving greater sensitivity, in comparison to the direct MS detection in the negative mode ( Lin et al, 2009).…”