title: Single drop microextraction using commercial capillary electrophoresis instruments.
abstract: Single drop microextraction (SDME), a simple and efficient sample preconcentration method for capillary electrophoresis (CE), was performed using two different commercial CE instruments. With a CE instrument providing adjustable forward and backward pressures, a single drop of an aqueous acceptor phase covered with a thin layer of an organic phase was formed at the capillary tip by programming the sample-handling functions of the instrument to perform 3-phase SDME where the organic film is essentially a membrane. Analytes from an acidic donor phase were concentrated into a basic acceptor phase yielding 190-fold enrichment in 10 min. When the donor phase was agitated using a microstirrer, a 2000-fold enrichment was obtained in 10 min. For a less flexible CE instrument, 2-phase SDME was carried out with a large volume pentanol drop held by a Teflon sleeve, yielding 110-fold enrichments in 30 min. We demonstrate a practical and automated SDME-CE technique with accuracy and reproducibility that is easy to practice to attain matrix isolation and high concentration sensitivity.
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 151-747, Korea.
authors.forename: Kihwan
authors.initials: K
authors.lastname: Choi
authors.forename: Su Ju
authors.initials: SJ
authors.lastname: Kim
authors.forename: Yoo Gon
authors.initials: YG
authors.lastname: Jin
authors.forename: Yong Oh
authors.initials: YO
authors.lastname: Jang
authors.forename: Jin-Soo
authors.initials: JS
authors.lastname: Kim
authors.forename: Doo Soo
authors.initials: DS
authors.lastname: Chung