A stacking approach in capillary electrophoresis based on the reversal of the analytes’ effective electrophoretic velocities at a dynamic stacking boundary formed between charged micelles (i.e., from long chain ionic surfactants) and neutral cyclodextrins (i.e., native α-, β-, or γ-cyclodextrin) is presented. The approach was demonstrated by the long injection of samples in a micellar solution followed by injection of a cyclodextrin solution zone, and then separation by co-electro-osmotic flow capillary zone electrophoresis. The reversal is caused by the formation of stable cyclodextrin–surfactant complexes at the boundary that significantly decreased the retention factor of the analytes in the presence of a micellar pseudostationary phase. The dynamic boundary was formed at the cyclodextrin zone as the micelles penetrated this zone. Under optimum conditions, the boundary disappears, and the stacking ends when all the micelles have electrophoretically migrated to the boundary. Cationic and anionic small molecules were enriched using oppositely charged micelles from sodium dodecyl sulfate and cetyltrimethylammonium bromide, respectively. There were 1–2 orders of concentration magnitude improvement in analyte detection, which is expected in stacking with hydrodynamic injection. The improvements in the peak signals (height/corrected area) were up to 236/445 and 101/76 for the cationic and anionic analytes tested, respectively. Linearity (r²) and repeatability (%RSD of migration time, peak height, and corrected peak area) under the chosen stacking conditions (cations/anions) were ≥0.998/≥0.995 and ≤3.8%/≤5.7%, respectively. The stacking approach was also implemented in the direct analysis of peptides from trypsin digested bovine serum albumin.

Item Type:	Refereed Article
Keywords:	analytical chemistry, electrophoresis
Research Division:	Chemical Sciences
Research Group:	Analytical chemistry
Research Field:	Separation science
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the chemical sciences
UTAS Author:	Quirino, JP (Associate Professor Lito Quirino)
UTAS Author:	Grochocki, W (Dr Wojciech Grochocki)
ID Code:	123458
Year Published:	2017
Web of Science® Times Cited:	16
Deposited By:	Austn Centre for Research in Separation Science
Deposited On:	2018-01-09
Last Modified:	2022-08-29
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