Electromembrane extraction of biological samples: determining stimulant drugs in whole blood

By R. Lucena -

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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