title: pH-independent large-volume sample stacking of positive or negative analytes in capillary electrophoresis.
abstract: In capillary electrophoresis, the short optical path length associated with on-column UV detection imposes an inherent detection problem. Detection limits can be improved using sample stacking. Recently, large-volume sample stacking (LVSS) without polarity switching was demonstrated to improve detection limits of charged analytes by more than 100-fold. However, this technique requires suppression of the electroosmotic flow (EOF) during the run. This necessitates working at a low pH, which limits using pH to optimize selectivity. We demonstrate that LVSS can be performed at any buffer pH (4.0-10.0) if the zwitterionic surfactant Rewoteric AM CAS U is used to suppress the EOF. Sensitivity enhancements of up to 85-fold are achieved with migration time, corrected area, and peak height reproducibility of 0.8-1.6%, 1.3-3.7%, and 0.8-4.9%, respectively. Further, it is possible to stack either positively or negatively charged analytes using zwitterionic surfactants to suppress the EOF.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: N E
authors.initials: NE
authors.lastname: Baryla
authors.forename: C A
authors.initials: CA
authors.lastname: Lucy
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000302:isolation & purification; D001622:Betaine / Q000031:analogs & derivatives / Q000737:chemistry; D001977:Brompheniramine / Q000302:isolation & purification; D002395:Catecholamines / Q000302:isolation & purification; D002412:Cations; D002744:Chlorpheniramine / Q000302:isolation & purification; D004295:Dihydroxyphenylalanine / Q000302:isolation & purification; D004155:Diphenhydramine / Q000302:isolation & purification; D004319:Doxylamine / Q000302:isolation & purification; D019075:Electrophoresis, Capillary / Q000379:methods*; D006634:Histamine H1 Antagonists / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D010632:Pheniramine / Q000302:isolation & purification; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002395:Catecholamines; D002412:Cations; D006634:Histamine H1 Antagonists; D013501:Surface-Active Agents; C400714:amidopropylhydroxydimethylsulfobetaine; D015102:3,4-Dihydroxyphenylacetic Acid; D010632:Pheniramine; D001622:Betaine; D002744:Chlorpheniramine; D004295:Dihydroxyphenylalanine; D004155:Diphenhydramine; D004319:Doxylamine; D001977:Brompheniramine