Read all posts from May 2014
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 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...(Read more)
Reverse
dispersive liquid-liquid microextraction for the isolation of Cd and Pb from
edible oils
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)...(Read more)
Making our scope
wider
On April 6th 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.
Composites of
silver nanoparticles and polyaniline for MEPS
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....(Read more)
Gold coated
magnetic beads for electrochemical detection
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),...(Read more)
Molecularly
imprinted polymer for the extraction and detection of insulin
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....(Read more)
Salting out
supported liquid extraction
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...(Read more)
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