Magnetomotive ionic liquids

By -
The potential of ionic liquids (ILs) in the microextraction context is beyond any doubt. ILs, especially those that are liquid at room temperature (RTILs), present a negligible vapour pressure (attractive in HS-SDME), tuneable solubility in water (interesting in in-situ solvent formation technique) and they may be tailored to extract target analytes by the proper selection of the forming ions. RTIL have been extensively used in DLLME for these reasons, its recovery after extraction, being usually developed by centrifugation thanks to their higher density than water. However, this centrifugation step is time-consuming and several alternatives like in-syringe DLLME have been proposed to avoid it.

Magnetic materials present a clear advantage over other materials in dispersive procedures as they can be recovered from the bulk solution using an external magnet. The combination of magnetic materials/ionic liquids has been studied from different approaches. For example, ILs can be used to cover the outer surface of magnetic particles (MPs). In the easiest way, ILs can be retained on the surface by electrostatic interactions. However, the preparation of such combination requires long IL-MNPs interaction times and the IL can be easily detached from the surface of the MPs (due to pH changes or solubilization in organic solvents) and therefore it may be present in the final eluate, which is not recommendable. This issue can be solved by the covalent binding of the IL to the MPs although this approach requires a multistep synthetic procedure.

There is another issue to consider when you use a NP as support. The size of the particle defines the superficial area and therefore, the efficiency of the IL interaction with the analyte. The lower the particle size, the higher the area and therefore, the use of magnetic nanoparticles (MNPs) is preferred over micrometric ones. But, where is the limit of the particle size? The answer is clear (and obvious). The lower limit is to avoid the use of MNPs (reducing the particle size to zero). I accept that this answer is contradictory and generates another question. How can we confer magnetic properties to an IL without a MNPs?. Magnetic ILs are the response to this question. Journal of Chromatography A has already published an article where a magnetomotive room temperature dicationic ionic liquid is synthesized and applied as solvent in DLLME (1). The IL, whose formula is presented in Figure 1, is prepared in two steps and presents magnetic properties due to the FeCl4-. Although the approach is very interesting, the IL exhibits a low solubility in water that limits its dispersability into the sample.

 Our colleagues have used the IL to extract Ag and Au ions from waters and ore samples after their complexation. The analytes are finally analyzed by ETAAS with LODs lower than 7.3 ng/L.

We recommend this article to our readers. In the original manuscript, you will find the synthetic protocol, the characterization of the solvent as well as the practical application.

Reference
(1) Magnetomotive room temperature dicationic ionic liquid: A new concept toward centrifuge-less dispersive liquid–liquid microextraction. Link to the article

Comments

Post a Comment

Popular posts from this blog

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

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

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