Non-supported electrodriven liquid microextraction

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Today, we focus the attention on an interesting article recently published in Journal of Chromatography A by researchers from the University of Tasmania at Australia. As our readers well known, electrodriven liquid microextraction techniques present a high efficiency for the extraction of charged analytes. In those techniques, the analytes migrate from the sample to the acceptor phase as a consequence of the voltage gradient established between both phases. In the off-line modes, the involved phases are often physically separated by an organic phase or a polymeric membrane impregnated with an appropriate organic solvent. Our colleagues have proposed a novel configuration that permits the development of the extraction procedure without any physical barrier between phases (1).

The device consists of a 20 µL micropipette (a microtube with length of 6.4 cm and inner diameter of 0.3 mm) where the acceptor phase is located. The upper part of the microtube is introduced into a syringe that contains a hydrogel while the lower part is immersed into the sample. Two electrodes, essential to create a voltage gradient, are finally introduced in the hydrogel and the sample. The complete device is schematically presented in the Figure. As the readers may infer, the hydrogel is the core of the system. It plays two different roles. On the one hand, it stabilizes the acceptor phase into the microtube and it also supported the electrical current during the extraction procedure. Therefore, in this approach the acceptor phase is in direct contact with the sample.

This electrodriven microextraction technique has been applied to the isolation and preconcentration of several anions from water samples providing enrichment factors as high as 249. In addition, the extraction is rapid and it lasts less than 20 min.

We strongly recommend this article to our readers. 

Reference

(1) Off-line sample preparation by electrophoretic concentration using a micropipette and hydrogel. Link to the article

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