idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
Prof. Dr. Jan Åke Jönsson
Center for Analysis and Synthesis, Department of Chemistry, Lund University, Sweden
Liquid phase microextraction can be performed in several ways, but the most efficient and convenient version is
membrane extraction using hollow fibers. Such techniques permit the application of classical liquid-liquid extraction
(LLE) chemistry in a miniaturized way. Various shortcomings of LLE are overcome as only very little organic
solvents are used, high enrichment factors can be obtained and there are no problems with emulsions. Disposable
material can be used, so the costs can be kept to a minimum and the technique is very suitable for work in the field or
in developing countries. With a three phase system (aq/org/aq) (sometimes called SLM, supported liquid membrane),
analytes are extracted from an aqueous sample into an organic liquid, immobilized in a porous hydrophobic
membrane support, and further to a second aqueous phase. This is suitable for the extraction of polar compounds
(acidic or basic, charged, metals, etc.) and it is compatible with reversed phase HPLC [1].
A two-phase system (aq/org) where analytes are extracted into an organic solvent separated from the aqueous sample
by a hydrophobic porous membrane is more suitable for hydrophobic analytes and is compatible with gas
chromatography. It is possible to perform extractions for sample clean-up and enrichment with very cheap and
simple equipment, leading to high enrichment factors (easily thousands of times) for trace analysis [2-4].
Usually a complete extraction of the analytes in a sample is attempted in order to determine the total concentration of
these analytes. This is similar to what is attempted with classical techniques such as LLE and SPE (solid phase
extraction).
An alternative and complementary way of working is to attempt equilibrium between the sample and the extraction
device, with minimum disturbance of the sample. These are the principles of “equilibrium extraction through
membranes” (ESTM) as recently was developed. [5-7]. This technique leads to the determination of the freely
dissolved concentration (i.e. not complexated or otherwise bound fraction) of the analyte. This is related to the
bioavailability, fugacity and chemical potential of a pollutant in the sample and is therefore significant for the
evaluation of toxicity and transport processes of the pollutant in the environment, both for polar organic compounds,
and for metal ions.
References
1. Jönsson, J.Å. and L. Mathiasson, J. Separation Sci., 2001. 24: 495-507.
2. Berhanu, T., J.-f. Liu, R. Romero, N. Megersa, and J.Å. Jönsson, J. Chromatogr. A, 2006. 1103: 1-8.
3. Fontanals, N., T. Barri, S. Bergström, and J.Å. Jönsson, J. Chromatogr. A, 2006. 1133: 41-48.
4. Zorita, S., L. Mårtensson, and L. Mathiasson, J. Separation Sci., 2007. 30: 2513-2521.
5. Liu, J.-f., J.Å. Jönsson, and P. Mayer,. Anal. Chem., 2005. 77: 4800-4809.
6. Romero, R., J.-f. Liu, P. Mayer, and J.Å. Jönsson, Anal. Chem., 2005. 77: 7605-7611.
7. Larsson, N., K. Utterback, L. Toräng, J. Risberg, P. Gustafsson, P. Mayer, and J.Å. Jönsson, Chemosphere, 2009.
75: 1213-1220.
Einladender : PD Dr. Richard Thede
gez. Prof. Dr. J. Heinicke
Vorsitzender des Ortsverbandes der
GDCh
Information on participating / attending:
Date:
05/26/2011 17:00 - 05/26/2011
Event venue:
Großer Seminarraum D213 des Instituts für Biochemie
Felix-Hausdorff-Str. 4
17489 Greifswald
Mecklenburg-Vorpommern
Germany
Target group:
Business and commerce, Scientists and scholars
Email address:
Relevance:
transregional, national
Subject areas:
Chemistry
Types of events:
Presentation / colloquium / lecture
Entry:
05/06/2011
Sender/author:
Sabine Köditz
Department:
Presse- und Informationsstelle
Event is free:
yes
Language of the text:
English
URL of this event: http://idw-online.de/en/event35296
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