Electromembrane extraction of biological samples: determining stimulant drugs in whole blood
Electromembrane
extraction (EME), which was firstly proposed in 2006 by Pedersen-Bjergaard and
Rasmussen, is based on the voltage-assisted migration of the target analytes
from two aqueous solutions: the sample and the acceptor phase. Both phases are
separated by a polymeric membrane where an organic solvent is immobilized in
the form of a supported liquid membrane (SLM).
EME shares some of the
principles and a similar manifold that this employed for hollow fiber-liquid
phase microextraction (HF-LPME). As it is schematized in the Figure, the sample
is located in an appropriate vessel where a polypropylene hollow fiber (HF) is introduced.
The HF contains the acceptor phase in the lumen and an organic solvent in the
internal pores acting as a physical barrier between the two aqueous solutions. Moreover,
the EME manifold involves two electrodes which are located in the sample and the
HF lumen, respectively. The voltage applied between both electrodes is the driving
force of this extraction procedure.
EME is an interesting
extraction technique for biosamples due to different reasons. On the one hand,
it allows the isolation and preconcentration of the target analytes with an
inherent improvement of selectivity and sensitivity which is essential in
bioanalysis. On the other hand, it can be easily adapted to the extraction of
low volume of samples which it is interesting when plasma or blood is analyzed.
Moreover, EME is faster (6-17 depending on the published application) than
conventional HF-LPME allowing the rapid decision making in specific problems. Taking
into account that EME does not require a stirring of the sample, the potential
emulsification of the SLM solvent with the biological matrix is also avoided.
In a recent article
published in Journal of Chromatography A, the potential of EME in the
extraction of six stimulant drugs from whole blood has been evaluated. Excellent
absolute recoveries (up to 25 %) are achieved in only 5 min of extraction,
allowing the determination of the targets also in the pg/mL level. Moreover, a common
5V-battery is employed to assist the extraction which highlights the simplicity of
the extraction procedure.
References
Link to article: Electrokinetic
migration across artificial liquid membranes: New concept for rapid sample
preparation of biological fluids.
Link to article: Electromembrane
extraction of stimulating drugs from undiluted whole blood
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