title: Sample stacking and sweeping in microemulsion electrokinetic chromatography under pH-suppressed electroosmotic flow.
abstract: Two on-line sample concentration techniques, sample stacking and sweeping under pH-suppressed electroosmotic flow, were evaluated in microemulsion electrokinetic chromatography. The concept of stacking with anion selective electrokinetic injection and a water plug in a reverse-migrating microemulsion (SASIW-RMME) was brought forward in this article. Six flavonoids were concentrated using a microemulsion consisting of 80 mM sodium dodecyl sulfate, 1.2% (v/v) ethyl acetate, 0.6% (v/v) 1-butanol, 10% acetonitrile (v/v) and 50 mM phosphoric acid (pH* 1.8). Significant detector response improvements were achieved. The limits of detection were in the low ng/ml level. Finally, the sample of Fructus aurantii Immaturus was analyzed using sweeping technique.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Zhu
authors.forename: Shengda
authors.initials: S
authors.lastname: Qi
authors.forename: Huige
authors.initials: H
authors.lastname: Zhang
authors.forename: Xingguo
authors.initials: X
authors.lastname: Chen
authors.forename: Zhide
authors.initials: Z
authors.lastname: Hu
mesh_terms: D000465:Algorithms; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D053841:Electroosmosis; D004655:Emulsions; D005419:Flavonoids / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D012996:Solutions
chemical_list: D004655:Emulsions; D005419:Flavonoids; D007202:Indicators and Reagents; D012996:Solutions