title: Liquid-phase microextraction as an on-line preconcentration method in capillary electrophoresis.
abstract: A simple and efficient sample preconcentration method for capillary electrophoresis has been developed using liquid-phase microextraction (LPME). A thin layer of an organic liquid was used to separate a drop of the aqueous acceptor phase hanging at the inlet of a capillary from the bulk aqueous donor phase. The donor-phase pH was 1.0, and the acceptor phase pH was 9.5. This pH difference caused the preconcentration of the acidic compounds, fluorescein and fluorescein isothiocyanate, into the acceptor-phase drop. Enrichment factors of 3 orders of magnitude were obtained with 30-min LPME at 35 degrees C.
authors.affiliation: School of Chemistry, Seoul National University, Seoul 151-747, Korea.
authors.forename: Kihwan
authors.initials: K
authors.lastname: Choi
authors.forename: Yongseong
authors.initials: Y
authors.lastname: Kim
authors.forename: Doo Soo
authors.initials: DS
authors.lastname: Chung