title: Implementation of droplet-membrane-droplet liquid-phase microextraction under stagnant conditions for lab-on-a-chip applications.
abstract: In the current work, droplet-membrane-droplet liquid-phase microextraction (LPME) under totally stagnant conditions was presented for the first time. Subsequently, implementation of this concept on a microchip was demonstrated as a miniaturized, on-line sample preparation method. The performance level of the lab-on-a-chip system with integrated microextraction, capillary electrophoresis (CE) and laser-induced fluorescence (LIF) detection in a single miniaturized device was preliminarily investigated and characterized. Extractions under stagnant conditions were performed from 3.5 to 15 microL sample droplets, through a supported liquid membrane (SLM) sustained in the pores of a small piece of a flat polypropylene membrane, and into 3.5-15 microL of acceptor droplet. The basic model analytes pethidine, nortriptyline, methadone, haloperidol, and loperamide were extracted from alkaline sample droplets (pH 12), through 1-octanol as SLM, and into acidified acceptor droplets (pH 2) with recoveries ranging between 13 and 66% after 5 min of operation. For the acidic model analytes Bodipy FL C(5) and Oregon Green 488, the pH conditions were reversed, utilizing an acidic sample droplet and an alkaline acceptor droplet, and 1-octanol as SLM. As a result, recoveries for Bodipy FL C(5) and Oregon Green 488 from human urine were 15 and 25%, respectively.
authors.affiliation: Division of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O. Box 56, FI-00014, University of Helsinki, Helsinki, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Sikanen
authors.forename: Stig
authors.initials: S
authors.lastname: Pedersen-Bjergaard
authors.forename: Henrik
authors.initials: H
authors.lastname: Jensen
authors.forename: Risto
authors.initials: R
authors.lastname: Kostiainen
authors.forename: Knut Einar
authors.initials: KE
authors.lastname: Rasmussen
authors.forename: Tapio
authors.initials: T
authors.lastname: Kotiaho
mesh_terms: D002264:Carboxylic Acids / Q000302:isolation & purification / Q000652:urine; D019075:Electrophoresis, Capillary / Q000379:methods*; D006220:Haloperidol / Q000032:analysis / Q000302:isolation & purification; D006801:Humans; D006863:Hydrogen-Ion Concentration; D056656:Lab-On-A-Chip Devices; D007834:Lasers; D008139:Loperamide / Q000032:analysis / Q000302:isolation & purification; D008614:Meperidine / Q000032:analysis / Q000302:isolation & purification; D008904:Miniaturization; D009661:Nortriptyline / Q000032:analysis / Q000302:isolation & purification; D000442:Octanols / Q000737:chemistry; D011126:Polypropylenes / Q000737:chemistry; D011162:Porphobilinogen / Q000031:analogs & derivatives / Q000302:isolation & purification / Q000652:urine; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: C538930:3-anilino difluoroboron dipyrromethene; D002264:Carboxylic Acids; D000442:Octanols; C436864:Oregon Green 488 carboxylic acid; D011126:Polypropylenes; D008139:Loperamide; D011162:Porphobilinogen; D008614:Meperidine; D009661:Nortriptyline; D006220:Haloperidol