Non-supported electrodriven liquid microextraction

By -
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

Comments

Post a Comment

Popular posts from this blog

Fabric phase sorptive extraction: a new generation green sample preparation strategy

By -
Image
by Dr. Abuzar Kabir, International Forensic Research Institute, Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, USA Fabric phase sorptive extraction (FPSE), the most recent member of the sorptive microextraction family, has innovatively incorporated both solid phase microextraction (SPME) and solid phase extraction (SPE) techniques into a single technology platform. FPSE utilizes permeable natural/synthetic fabrics e.g., cotton, polyester, fiber glass supports to chemically bind sol-gel hybrid inorganic-inorganic sorbents. A 5 cm2unit of coated fabric (2.5 cm x 2.0 cm) is typically used as the extraction media which can be inserted directly into the sample container. Extraction of the analytes is generally expedited by using a magnetic stir bar to diffuse the analyts into the sample matrix so that rapid mass transfer from the sample matrix to the extraction medium takes place.Once the mass transfer equilibrium between the FPSE media and
Read more

Gold coated magnetic beads for electrochemical detection

By -
Image
This post summarizes an interesting article, recently accepted for publication in Analytical Chemistry, which presents an innovative use of magnetic beads. Researchers from the Osaka Prefecture University at Japan have proposed the synthesis of magnetic microbeads covered with a smooth gold layer that are used for the electrochemical detection of streptavidin (1). The synthesis, which is deeply described in the manuscript, consists of three well defined steps. First of all, the magnetic beads are introduced in a colloidal gold dispersion containing Au-nanoparticles (Au-NPs). Thanks to the opposite zeta potential of both materials (microbeads are negatively charged while Au-NPs present a positive charge), their assembly takes place by electrostatic interactions. However, the Au-NPs are not connected to each other and therefore the electrical resistance of the microbeads is too high. In a second step, the modified microbeads are dispersed in an aqueous medium containing HAuCl 4 as
Read more

Rotating Disk Sorptive Extraction

By -
Image
by Prof. Dr. Pablo Richter, Department of Inorganic and Analytical Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile. The modern trends in analytical chemistry promote efficiency and green technology in sample preparation. In this context, our research team developed a new technique in 2009 that is capable of extracting pollutants from liquid samples on a rotating PTFE disk with one surface coated with an extraction phase [1]. The disk has embedded a miniature magnetic rod, which allows rotation. We have termed this procedure rotating-disk sorptive extraction (RDSE). RDSE is currently available in two configurations. In the classic version (Figure 1), the extraction phase is a polymeric film adhered to one side of the PTFE disk (configuration 1). In this configuration, polydimethylsiloxane (PDMS), nylon and octadecyl (C18) have been used as the sorptive material for the extraction of low-polarity analytes (Log Kow between 3 and 7) [1-12]. However
Read more