title: Micro-electromembrane extraction across free liquid membranes. Instrumentation and basic principles.
abstract: A micro-electromembrane extraction (μ-EME) technique using electrically induced transfer of charged analytes across free liquid membranes (FLMs) was presented. A disposable extraction unit was proposed and it was made of a short segment of transparent perfluoroalkoxy tubing, which was successively filled with three liquid plugs serving as acceptor solution, FLM and donor solution. These plugs formed a three-phase extraction system, which was precisely defined, that was stable and required μL to sub-μL volumes of all respective solutions. Basic instrumental set-up and extraction principles of μ-EME were examined using an anionic and a cationic dye, 4,5-dihydroxy-3-(p-sulfophenylazo)-2,7-naphthalene disulfonic acid trisodium salt (SPADNS) and crystal violet, respectively. Transfers of the charged dyes from donor into acceptor solutions across FLMs consisting of 1-pentanol were visualized by a microscope camera and quantitative measurements were performed by UV-vis spectrophotometry. The effects of operational parameters of μ-EME system were comprehensively investigated and experimental measurements were accompanied with theoretical calculations. Extraction recoveries above 60% were achieved for 5min μ-EME of 1mM SPADNS at 100V with repeatability values below 5%. Selectivity of FLMs was additionally examined by capillary electrophoretic analyses of acceptor solutions and the potential of FLMs for μ-EME pretreatment of samples with artificial complex matrices was demonstrated.
authors.affiliation: Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic, v. v. i., Veveří 97, CZ-60200 Brno, Czech Republic. Electronic address: kuban@iach.cz.
authors.forename: Pavel
authors.initials: P
authors.lastname: Kubáň
authors.affiliation: Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic, v. v. i., Veveří 97, CZ-60200 Brno, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Boček
mesh_terms: D000838:Anions / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D004396:Coloring Agents / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D008567:Membranes, Artificial; D000439:Pentanols / Q000737:chemistry; D015203:Reproducibility of Results; D013057:Spectrum Analysis
chemical_list: D000838:Anions; D002412:Cations; D004396:Coloring Agents; D008567:Membranes, Artificial; D000439:Pentanols; C024999:n-pentanol
keywords: Free liquid membranes; Micro-electromembrane extraction; SPADNS, UV–vis spectrophotometry