title: New pressure-assisted sweeping on-line preconcentration for polar environmentally relevant nitrosamines: Part 1. sweeping for polar compounds and application of auxiliary pressure.
abstract: Typically sweeping reversed migration EKC (RM-EKC) is used for online enrichment and separation of neutral compounds in CE, however sweeping is not usually suitable for highly polar neutral compounds due to the lack of strong interaction with micellar phase. Since acidic BGE or coated capillaries (BGE pH 2-8) are used to virtually eliminate the EOF, migration of neutral analytes is only through association with the micelles with relatively slow electrophoretic mobility. To decrease the long analysis times that result, an auxiliary pressure can be applied, which also serves to avoid the associated band broadening. In this study, we have modified a commercially available CE instrument to perform pressure-assisted sweeping. The apparatus described can be used to precisely control the application of pressure, and therefore direction and magnitude of bulk flow in the capillary. This modification allows us to employ longer capillaries and capillaries with larger internal diameter to increase the sensitivity. An optimized method was used for the analysis of a group of seven N-nitrosamines that have been widely reported in environmental samples and good concentration factors of up to 34 were achieved. When a coated capillary is employed, this method is effective even at neutral pH, making it broadly applicable.
authors.affiliation: Department of Chemistry, Memorial University of Newfoundland, Canada.
authors.forename: Ali
authors.initials: A
authors.lastname: Modir-Rousta
authors.forename: Christina S
authors.initials: CS
authors.lastname: Bottaro
mesh_terms: D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D053841:Electroosmosis; D019075:Electrophoresis, Capillary / Q000379:methods*; D009602:Nitrosamines / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D011312:Pressure; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D009602:Nitrosamines; D013501:Surface-Active Agents
keywords: N-nitrosamines; Neutral polar compounds; On-line preconcentration; Pressure-assisted sweeping; Reversed migration-electrokinetic chromatography