title: Three-step stacking by field-enhanced sample injection, sweeping, and micelle to solvent stacking in capillary electrophoresis: Anionic analytes.
abstract: Three-step stacking by field-enhanced sample injection (FESI), sweeping, and micelle to solvent stacking (MSS) in co-EOF capillary zone electrophoresis (CZE) is presented for anionic analytes. Long FESI produced an overloaded stacked zone of analytes (four model penicillins). Sweeping of the FESI zone was by electrokinetic injection of cetyltrimethylammonium bromide (CTAB) micelles. MSS was by short injection of 60% methanol that released the swept analytes from CTAB micelles. The sensitivity enhancement factors were 146-279 and 519-954 for conductivity ratio of 10 and 100, respectively. The SEF enhancement factors (factor=SEF from three-step stacking/SEF from FESI) were 16-32 and 6-10, correspondingly. The LODs were between 6.6-13.2 ng/mL, repeatability (intraday and interday) was %RSD≤5.4%, and linearity was R(2)≥0.998. Application to real sample was investigated using fortified plasma after liquid-liquid extraction.
authors.affiliation: Australian Centre for Research on Separation Science (ACROSS), School of Physical Sciences-Chemistry, University of Tasmania, Hobart, Australia; Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdansk, Gdansk, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Grochocki
authors.affiliation: Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdansk, Gdansk, Poland.
authors.forename: Michał J
authors.initials: MJ
authors.lastname: Markuszewski
authors.affiliation: Australian Centre for Research on Separation Science (ACROSS), School of Physical Sciences-Chemistry, University of Tasmania, Hobart, Australia; Department of Chemistry, Ateneo de Manila University, Katipunan Avenue, Loyola Heights, Quezon City 1108, Philippines. Electronic address: jquirino@utas.edu.au.
authors.forename: Joselito P
authors.initials: JP
authors.lastname: Quirino
mesh_terms: D000838:Anions / Q000737:chemistry; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D059625:Liquid-Liquid Extraction; D000432:Methanol / Q000737:chemistry; D008823:Micelles; D012997:Solvents
chemical_list: D000838:Anions; D002593:Cetrimonium Compounds; D008823:Micelles; D012997:Solvents; D000432:Methanol; D000077286:Cetrimonium
keywords: Anionic analytes; Capillary electrophoresis; Field-enhanced sample injection; Micelle to solvent stacking; Stacking; Sweeping