Stir bar dispersive liquid microextraction using magnetic ionic liquids

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  • Published: Jul 6, 2017
  • Author: Rafael Lucena
  • Channels: HPLC / Proteomics & Genomics / Electrophoresis / Detectors / Laboratory Informatics / Sample Preparation / Ion Chromatography / Gas Chromatography / Base Peak / NMR Knowledge Base / Raman / MRI Spectroscopy / UV/Vis Spectroscopy / Infrared Spectroscopy / Chemometrics & Informatics / Atomic / Proteomics / X-ray Spectrometry

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The combination of different types of extraction techniques is a fascinating and ever evolving field. The combination is usually achieved in a discontinuous manner by which the extract obtained after application of the first extraction is then submitted to the next technique. If the chemical basics of both techniques are sufficiently different, then a selectivity enhancement is achieved. In other cases the extraction efficiency can also be improved by such combinations. The number of approaches that combine two extraction techniques in the same procedure are quite rare. ICECLES based on the combination of stir bar sorptive extraction (SBSE) and freeze extraction is one of the most recent proposals. This post is dedicated to one of these interesting strategies.

In 2014, Benedé et al. proposed for the first time the so-called stir bar sorptive dispersive microextraction. As with many good ideas, the system was both simple and efficient. It combined the advantages of SBSE and dispersive magnetic solid phase extraction. The extraction scheme is shown in the figure below and it experiments with different stirring rates of the magnetic bar. In the first step, the bar containing the attached magnetic nanoparticles (MNPs) is introduced into the sample. The bar is then stirred at a high velocity inducing the detachment of the MNPs which are dispersed into the sample enhancing the active superficial area. The continuous reduction of the stirring velocity induces the re-attachment of the MNPs onto the bar simplifying the final elution step.

The same group in collaboration with Professor Jared Anderson´s group at Iowa State University has already extended this approach to the liquid phase microextraction context using magnetic ionic liquids as solvents. The extraction process follows the same steps as previously described.

Ionic liquids provide a high sorption capacity and their thermal stability makes them compatible with thermal desorption-gas chromatography. This new combination has been tested for the extraction of non-polar UV filters. Enrichment factors in the range from 67-791, similar to those provided by classical SBSE, are achieved. However the new technique is almost 20 times faster than the classical one.

References:

  1. Microextraction Tech blog. 2014. Stir bar sorptive dispersive microextraction mediated by magnetic nanoparticles.
  2. J. Chromatogr. A, 2014, 1362, 25. Benedé et al. Development of stir bar sorptive-dispersive microextraction mediated by magnetic nanoparticles and its analytical application to the determination of hydrophobic organic compounds in aqueous media.
  3. Anal. Chim Acta, 2017, in press. Anderson et al. Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction.

Blog post by: Rafael Lucena

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