title: Drop-to-drop microextraction across a supported liquid membrane by an electrical field under stagnant conditions.
abstract: Electromembrane extraction (EME) of basic drugs from 10 microL sample volumes was performed through an organic solvent (2-nitrophenyl octyl ether) immobilized as a supported liquid membrane (SLM) in the pores of a flat polypropylene membrane (25 microm thickness), and into 10 microL 10 mM HCl as the acceptor solution. The driving force for the extractions was 3-20 V d.c. potential sustained over the SLM. The influence of the membrane thickness, extraction time, and voltage was investigated, and a theory for the extraction kinetics is proposed. Pethidine, nortriptyline, methadone, haloperidol, and loperamide were extracted from pure water samples with recoveries ranging between 33% and 47% after only 5 min of operation under totally stagnant conditions. The extraction system was compatible with human urine and plasma samples and provided very efficient sample pretreatment, as acidic, neutral, and polar substances with no distribution into the organic SLM were not extracted across the membrane. Evaluation was performed for human urine, providing linearity in the range 1-20 microg/mL, and repeatability (RSD) in average within 12%.
authors.affiliation: Department of Pharmaceutics and Analytical Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark.
authors.forename: Nickolaj Jacob
authors.initials: NJ
authors.lastname: Petersen
authors.forename: Henrik
authors.initials: H
authors.lastname: Jensen
authors.forename: Steen Honoré
authors.initials: SH
authors.lastname: Hansen
authors.forename: Knut Einar
authors.initials: KE
authors.lastname: Rasmussen
authors.forename: Stig
authors.initials: S
authors.lastname: Pedersen-Bjergaard
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D055664:Electrochemical Techniques / Q000379:methods*; D019075:Electrophoresis, Capillary / Q000379:methods; D008567:Membranes, Artificial; D008956:Models, Chemical; D004364:Pharmaceutical Preparations / Q000097:blood / Q000302:isolation & purification / Q000652:urine; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D008567:Membranes, Artificial; D004364:Pharmaceutical Preparations