Read all posts from September 2014

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Continuous flow micro-electroextraction for enrichment of low abundant compounds

 

IIt is well known by all the readers that achieving the highest enrichment is the key factor in any miniaturized extraction technique. In this sense, the use of highly efficient materials is a valuable alternative but not the only one. The use of auxiliary energies which force the analyte migration from the sample to the extractant phase is also a widespread alternative. Among them, electromigration-based microextraction is an elegant approach which allows the focusing and stacking of charged compounds within a short temporal window. (Read more)

Switchable hydrophilicity solvents in the microextraction context


The concept of switchable solvents (SS) was firstly introduced by Canter in 2006, in the framework of industrial processes. The initial idea was to introduce solvents which can switch between a polar and non-polar chemical form, aiming to reduce the number of organic solvent and toxic wastes generated during extraction procedures [1]. Recently, professor Jessop and co-workers expands the application field of this kind of solvents in order to develop cheaper and greener chemical processes.(Read more)

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Gold coated magnetic beads for electrochemical detection

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

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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...
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Rotating Disk Sorptive Extraction

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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...
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