Microextraction Tech

Simultaneous liquid phase microextraction with multiple solvents In a recent article published in Analytical Methods, researchers from the Shanxi Medical University at China have presented a novel microextraction approach for the determination of flavanoids and anthraquinones from traditional Chinese herbs. The authors use two different organic solvents placed in two filter membranes as extraction device. The main advantage of the so-called multiple-solvent simultaneous microextraction (MSSME) are the wide exchange surface and the selective extraction provided by the organic solvents used.  (Read more) Agro-industrial wastes as precursors for adsorbent synthesis Microextraction techniques can be considered within the Green Chemistry framework as they reduce the amount of materials and organic solvents required for the development of an analytical methodology. This green character is more marked when the microextraction technique is employed to the resolution of...

Analytica Chimica Acta (ACA) has published a novel analytical method which combines extraction and clean-up in a single step. The so-called salting out supported liquid extraction (SOSLE) follows the liquid-liquid extraction principles, its main advantage being the capability of extracting compounds of a wide polarity range (1). The technique was evaluated using the multi-residue quantification of veterinary drugs in milk as model analytical problem. Acetonitrile was selected as extractant and the immiscibility with the aqueous sample is achieved by using a high concentration of ammonium sulfate, thus permitting the supported liquid-liquid extraction (SLE) using a polar organic solvent. The benefits of SLE technique has been recognized  by Ronald E. Majors, editor of "Sample Preparation Perspectives" in LC/GC journal, who defined it as the best kept secret in sample preparation (2). The approach presented in ACA by our colleagues from Zurich overcomes the limitation of c...

Since the development of solid phase microextraction (SPME), several alternatives for the fiber coating have been proposed to open the applicability of this microextraction technique to as much families of compounds as possible. Moreover, looking for higher selectivity is also a transversal research line in this methodology. Molecularly imprinted polymers (MIPs) can be used for this purpose although they are still scarcely used as coatings in SPME. MIP micro-solid phase extraction (MIMSPE) is a renovated version of MIP-SPME. The main difference between both techniques is the extent to which the analyte is extracted, being exhaustive for the formed which can be considered as a total recovery extraction method. One of the latest articles published in Journal of Chromatography A combines MIMSPE with a multiwalled carbon nanotubes-MIP composite sensor. The main goal of this proposal is to achieve a high sensitivity thanks to the double preconcentration carried out in the extraction a...

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 ...

The combination of highly efficient sorbent with commercially available extraction devices is the best way to consolidate microextraction techniques in routine laboratories. The potential of nanoparticles in this context is undeniable. In this regard, our colleagues of the Sharif University of Technology (Tehran, Iran) have evaluated the potential of a novel nanocomposite for microextraction in packed syringe (1). The new sorbent is based on silver nanoparticles/polyaniline (Ag NPs/PANI) and it was prepared by using interfacial polymerization. The procedure is rather simple and it is performed in an aqueous/organic biphasic system being the Ag NPs/PANI nanocomposite formed in the interface. The evolution of the reaction can be easily followed by the color change of the mixture which starts with a free color at the interface which becomes darker in the organic phase and eventually stop changing, indicating the reaction completion. After 24 h of ageing, the composite can be separate...

On April 6 th 2011, we launched @microextraction on Twitter. Our main objective was to present a periodic digest of those research publications devoted to sample preparation, paying special attention to microextraction approaches. We considered that this bibliographic update could be attractive for all those researchers interested in the role that those techniques may play in the development of a competitive analytical methodology. Moreover, as researchers in this field, the twitter account was also valuable for us since we were aware of any innovation or application. On March 2012, we launched this blog as a new platform to highlight special contributions to the topic. As the research lines in any scientific career are in a continuous evolution, we would like to extend the scope of our resources to other topics, including analytical nanotechnology and sensors. This decision relies on different additional reasons, which are described below. The role that nanoparticles (NPs) ...

Dispersive liquid-liquid microextraction (DLLME) is a consolidated sample treatment technique which is characterized by its high efficacy leading to high enrichment factors. In the normal mode, the technique consists of the dispersion of a mixture of disperser and extraction solvents into the aqueous sample. The dispersion forms a cloudy state consisting of a innumerable extractant droplets which favors the transference of the analyte from the bulk sample. Hashemi et al. (1) adapted this technique to the extraction of non-aqueous phases giving rise to the so-called reverse phase DLLME (RP-DLLME). Reverse DLLME has been recently applied by researchers of the University of Murcia (Spain) for the extraction of cadmium and lead from edible oils (2). This is a problem of concern due to the inherent toxicity of both elements and their capability to influence some oxidative reactions that may lead to toxic compounds. To perform the RP-DLLME the sample is extracted with a mixture containi...

Microextraction techniques can be considered within the Green Chemistry framework as they reduce the amount of materials and organic solvents required for the development of an analytical methodology. This green character is more marked when the microextraction technique is employed to the resolution of an environmental analytical problem. This post is focused on another green concern: the use of wastes for the fabrication of sorbent materials for analytical purposes. Researchers from the Federal University of Rio Grande do Sul (Brazil) have already proposed, in an article published in Journal of Hazardous Materials , the use of coffee grounds and eucalyptus sawdust for the preparation of activated carbon. According to the authors, these agro-industrial wastes are quite problematic since their natural degradation favors the proliferation of some harmful microorganisms. The synthesis of the activated carbon just involves various simple processes. First of all, the coffee grounds an...

In a recent article published in Analytical Methods, researchers from the Shanxi Medical University at China have presented a novel microextraction approach for the determination of flavanoids and anthraquinones from traditional Chinese herbs. The authors use two different organic solvents placed in two filter membranes as extraction device. The main advantage of the so-called multiple-solvent simultaneous microextraction (MSSME) are the wide exchange surface and the selective extraction provided by the organic solvents used. The miniaturized extraction unit (see Figure) was constructed as follows. Two square pieces (1cm X 1cm) of filter membrane were separately immersed in 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6mim][PF 6 ]) and decanol for 10 s. In this way, the pores of the membrane are impregnated with the extractants. The excess of the solvents was removed using absorbent paper. Once prepared, the solvent impregnated membranes were pierced by a microsyringe needle...