title: Kinetic electro membrane extraction under stagnant conditions--fast isolation of drugs from untreated human plasma.
abstract: Amitriptyline, citalopram, fluoxetine, and fluvoxamine were isolated by electro membrane extraction (EME) from 70microl of untreated plasma (pH 7.4), through a supported liquid membrane (SLM) of 1-ethyl-2-nitrobenzene immobilized in the pores of a porous polypropylene hollow fiber, and into 30microl of 10mM HCOOH as acceptor solution inside the lumen of the hollow fiber. The driving force of the extraction was a 9V potential sustained over the SLM with a common battery, with the positive electrode placed in the plasma sample and the negative electrode placed in the acceptor solution. Extractions were performed under totally stagnant conditions with a very simple device for 1min (kinetic regime), and subsequently the acceptor solution was analyzed directly by liquid chromatography-mass spectrometry (LC-MS). Recoveries were 12, 13, 22, and 17% for fluoxetine, amitriptyline, citalopram, and fluvoxamine, respectively. Sample clean-up was comparable to reversed-phase solid-phase extraction (SPE), but EME required substantially less time than SPE. The time advantage of EME was further improved by parallel extraction of three samples (for 1min) with the same 9V battery. EME from plasma combined with LC-MS provided limits of quantification (S/N=10) in the range 0.4-2.3ng/ml, linearity in the range 1-1000ng/ml with r(2)-values of 0.998-0.999, and repeatability in the range 3.2-8.9% RSD in the mid-therapeutic window (100ng/ml).
authors.affiliation: Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway.
authors.forename: Lars Erik Eng
authors.initials: LE
authors.lastname: Eibak
authors.forename: Astrid
authors.initials: A
authors.lastname: Gjelstad
authors.forename: Knut Einar
authors.initials: KE
authors.lastname: Rasmussen
authors.forename: Stig
authors.initials: S
authors.lastname: Pedersen-Bjergaard
mesh_terms: D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007700:Kinetics; D008567:Membranes, Artificial; D004364:Pharmaceutical Preparations / Q000097:blood* / Q000737:chemistry; D052616:Solid Phase Extraction / Q000295:instrumentation / Q000379:methods*
chemical_list: D008567:Membranes, Artificial; D004364:Pharmaceutical Preparations