Author
Stig Pedersen-Bjergaard
Other affiliations: University of Waterloo, Technical University of Denmark, University of Oslo
Bio: Stig Pedersen-Bjergaard is an academic researcher from University of Copenhagen. The author has contributed to research in topics: Extraction (chemistry) & Capillary electrophoresis. The author has an hindex of 57, co-authored 227 publications receiving 11283 citations. Previous affiliations of Stig Pedersen-Bjergaard include University of Waterloo & Technical University of Denmark.
Papers published on a yearly basis
Papers
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TL;DR: Liquid-liquid-liquid microextraction (LLLME) served as a technique for sample cleanup since large molecules, acidic compounds, and neutral components were not extracted into the acceptor phase.
Abstract: Methamphetamine as a model compound was extracted from 2.5-mL aqueous samples adjusted to pH 13 (donor solution) through a thin phase of 1-octanol inside the pores of a polypropylene hollow fiber and finally into a 25-microL acidic acceptor solution inside the hollow fiber. Following this liquid-liquid-liquid microextraction (LLLME), the acceptor solutions were analyzed by capillary zone electrophoresis (CE). Extractions were performed in simple disposable devices each consisting of a conventional 4-mL sample vial, two needles for introduction and collection of the acceptor solution, and a 8-cm piece of a porous polypropylene hollow fiber. From 5 to 20 different samples were extracted in parallel for 45 min, providing a high sample capacity. Methamphetamine was preconcentrated by a factor of 75 from aqueous standard solutions, human urine, and human plasma utilizing 10(-1) M HCl as the acceptor phase and 10(-1) M NaOH in the donor solution. In addition to preconcentration, LLLME also served as a technique for sample cleanup since large molecules, acidic compounds, and neutral components were not extracted into the acceptor phase. Utilizing diphenhydramine hydrochloride as internal standard, repetitive extractions varied less than 5.2% RSD (n = 6), while the calibration curve for methamphetamine was linear within the range 20 ng/microL to 10 micrograms/mL (r = 0.9983). The detection limit of methamphetamine utilizing LLLME/CE was 5 ng/mL (S/N = 3) in both human urine and plasma.
1,163 citations
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TL;DR: Electrokinetic migration across thin artificial liquid membranes may be an interesting tool for future isolation within chemical analysis and may serve as an efficient tool for controlling the transport selectivity.
582 citations
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TL;DR: A recent review as discussed by the authors focuses on basic extraction principles, technical set-up, recovery, enrichment, extraction speed, selectivity, applications, and future trends in hollow fibre-based liquid-phase microextraction.
Abstract: The demand for automation in analytical liquid-liquid extraction (LLE) combined with organic solvent reduction or elimination has led to the recent development of liquid-phase microextraction (LPME) based on disposable hollow fibres. In this concept, analytes of interest are extracted from aqueous samples, through a thin layer of organic solvent immobilized within the pores of a porous hollow fibre, and into an acceptor solution inside the lumen of the hollow fibre. Subsequently, the acceptor solution is directly subjected to a final analysis by capillary gas chromatography (CGC), high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), or mass spectrometry (MS) without any further effort. Hollow fibre-based LPME may provide high analyte pre-concentration and excellent sample clean-up, and it has a broad application potential within areas such as drug analysis and environmental monitoring. This review focuses on basic extraction principles, technical set-up, recovery, enrichment, extraction speed, selectivity, applications, and future trends in hollow fibre-based LPME.
494 citations
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TL;DR: In this review, LPME will be discussed with focus on extraction principles, historical development, fundamental theory, and performance.
452 citations
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TL;DR: Important applications of LPME are reviewed with special focus on bioanalytical and environmental chemistry, and a new possible direction is covered namely electromembrane extraction, where analytes are extracted through the SLM and into the acceptor phase by the application of electrical potentials.
381 citations
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28,685 citations
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TL;DR: This book by a teacher of statistics (as well as a consultant for "experimenters") is a comprehensive study of the philosophical background for the statistical design of experiment.
Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON
13,333 citations
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TL;DR: An extensive review of existing data in the form of tables, encompassing many therapeutic classes is presented and the different contamination sources as well as fate and both acute and chronic effects on non-target organisms are reviewed.
1,281 citations