title: Combination of Electromembrane Extraction and Liquid-Phase Microextraction in a Single Step: Simultaneous Group Separation of Acidic and Basic Drugs.
abstract: Electromembrane extraction (EME) and liquid-phase microextraction (LPME) were combined in a single step for the first time to realize simultaneous and clear group separation of basic and acidic drugs. Using 2-nitrophenyl octyl ether as the supported liquid membrane (SLM) for EME and dihexyl ether as the SLM for LPME, basic and acidic drugs were extracted and separated simultaneously from a low pH sample by EME and LPME, respectively. After 15 min of extraction, basic drugs (citalopram and sertraline) were exhaustively extracted, whereas the recoveries for acidic drugs (ketoprofen and ibuprofen) were in the range of 76%-86%. Longer extraction time provided higher recoveries for the acidic drugs, but this somewhat deteriorated the group separation. Matrices effects from the coexisting acidic drugs/basic drugs were tested, and we observed that simultaneous EME/LPME was not affected by coexisting drugs at high concentration. This approach was further investigated from human plasma. Extraction recoveries were strongly dependent on dilution of plasma with buffer and on extraction time. Finally, this simultaneous EME/LPME approach was evaluated in combination with liquid chromatography (LC)-MS. The linearity ranges for the basic and acidic drugs were 10-600 ng/mL and 1-60 μg/mL, respectively, with R(2) > 0.997 for all analytes. The repeatability at three different levels for all analytes was less than 15%. The limits of quantification (LOQ, S/N = 10) were found to be 4.0-6.3 ng/mL and 0.6-0.9 μg/mL for basic and acidic drugs, respectively. Simultaneous EME/LPME enabled efficient group separation of basic and acidic analytes under optimum experimental conditions for both EME and LPME.
authors.affiliation: †School of Pharmacy, University of Oslo, PO Box 1068, Blindern, 0316 Oslo, Norway.
authors.forename: Chuixiu
authors.initials: C
authors.lastname: Huang
authors.affiliation: †School of Pharmacy, University of Oslo, PO Box 1068, Blindern, 0316 Oslo, Norway.
authors.forename: Knut Fredrik
authors.initials: KF
authors.lastname: Seip
authors.affiliation: †School of Pharmacy, University of Oslo, PO Box 1068, Blindern, 0316 Oslo, Norway.
authors.forename: Astrid
authors.initials: A
authors.lastname: Gjelstad
authors.forename: Xiantao
authors.initials: X
authors.lastname: Shen
authors.affiliation: †School of Pharmacy, University of Oslo, PO Box 1068, Blindern, 0316 Oslo, Norway.|⊥Department of Pharmacy, Faculty of Health and Medical Sciences, Faculty of Pharmaceutical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark.
authors.forename: Stig
authors.initials: S
authors.lastname: Pedersen-Bjergaard
mesh_terms: D002853:Chromatography, Liquid; D059627:Liquid Phase Microextraction; D013058:Mass Spectrometry; D008567:Membranes, Artificial; D004364:Pharmaceutical Preparations / Q000302:isolation & purification*
chemical_list: D008567:Membranes, Artificial; D004364:Pharmaceutical Preparations