Fully automated electromembrane extraction

By -
The implementation of microextraction techniques in process laboratories usually depends on their automation degree. In reality, the use of too manual procedures is not practical when a large number of samples must be processed. In addition, manual workflows are labor intensive and prone to errors. This situation can be further complicated when risky samples, pretty common in bioanalysis, are handled.

The potential of electromembrane extraction (EME) has been highlighted several times in Microextraction Tech blog. Among other advantages, EME is a rapid process thanks to the migration of the target compounds from the sample to the acceptor phase (through an appropriate supported liquid membrane) under an electrical voltage gradient. No doubt, the automation of EME and its hyphenation to chromatographic techniques would have a high impact in the field.

Researchers from the universities of Copenhagen and Oslo have reported this year two interesting articles in this context. Earlier in this year, they described the direct combination of EME and liquid chromatography-mass spectrometry (LC-MS) in a highly recommendable article published in Analytica Chimica Acta (1). Despite the interest of this approach, this post is focused on a recent article accepted for publication in Analytical Chemistry. In this case, our colleagues go beyond to the "simple" automation and coupling. In fact, they propose the integration of EME in a LC-MS autosampler.

The modification of the autosampler syringe makes this integration possible while enabling the subsequent extraction of several samples (each one located in a different vial of the autosampler tray). Although we recommend reading the original article to fully understand the proposal, a brief description is outlined before.

The core of the system, which is schematically shown in the Figure, consists of a hollow fiber (HF) whose ends are attached to fused capillary tubes. The acceptor phase flows through that inner volume and it is finally placed in the loop of a switching valve that allows its injection in the LC. The hollow fiber is located in the luer adapter of the syringe in such a way that the sample comes in close contact with the HF when it is aspirated from the vial by the syringe. An electrical wire and a voltage sequencer are the last elements needed to integrate EME with LC. Several steps (e.g aspiration of the sample, extraction and injection) are developed in a sequential and automated way. We strongly recommend the movie published as supplementary information and freely available on the journal webpage since it clearly explains all the process.
Scheme of the proposed device (more info in the original manuscript)

This is just a brief excerpt of the article and you will find additional info in the original article. Among this info, you will read a comprehensive description of the device, the optimization of the experimental variables involved in the extraction and the practical application to study the in-vivo conversion of methadone by rat liver microsomes.

References
(1) Direct coupling of a flow–flow electromembrane extraction probe to LC-MS. Link to the article
(2) Fully Automated Electro Membrane Extraction Autosampler for LC–MS Systems Allowing Soft Extractions for High-Throughput Applications. Link to the article
Related posts
(A) Electromembrane extraction of biological samples: determining stimulant drugs in whole blood. Link to the post
(B) Simultaneous electromembrane extraction of acidic and basic drugs. Link to the post
(C) Dynamic electromembrane extraction. Link to the post

Comments

  1. Bullion Jackpot CallSeptember 26, 2016 at 5:24 AM

    thanks for sharing full concepts of Fully automated electromembrane extraction.

    ReplyDelete

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