Read all posts from June 2014

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Accelerated solvent extraction for the evaluation ofprenatal exposure to drugs of abuse


Drug abuse is an important and worldwide problem with several health and legal connotations. The intake of these substances during pregnancy is especially critical since it affects both the mother and the growing infant. In this sense, potential effects caused by drug intake include decreased birth weight, body length and head circumference, intra-uterine growth retardation, impairment of normal fetal brain development, placental insufficiency, fetal distress, intra-uterine death, and a higher risk of premature birth.(Read more)

Monitoring a single C18 particle by confocal Raman microscopy


Solid phase extraction (SPE) is a consolidated sample treatment technique based on the retention of the target analytes in an appropriate sorbent thanks to different chemical interactions. SPE allows the enhancement of the selectivity and sensitivity of an analytical methodology through removing potential interferences and increasing the concentration of the target compounds. The latter depends directly on the extraction efficiency (defined as the absolute extraction recovery), as well as the volumes of the sample processed and the final eluent. Objectively seen, the final elution produces a dilution of the analyte which is previously confined in a lower amount/volume of the sorptive phase, thus reducing the potential enrichment factors of the technique. (Read more)

MIPintegration into a fiber-optic evanescent sensor

Analytical and Bioanalytical Chemistry journal has published a novel miniaturized extraction method for the determination of bisphenol A in plastic products treated at different temperatures. The main advantage of the proposed approach is that it is a fiber-optic evanescent wave sensor. In this case, a molecularly imprinted polymer is synthesized on a fiber column to which an optical fiber is adapted. As far as the detection limit is concerned, the sensor uses a low volume cell (20 µL) formed by the fiber and the capillary. The main innovation of this sensing device is that the fiber optical column and capillary (Read more)

Massspectrometric analysis of surfaces by electro-focusing liquid extractive surface analysis (EF-LESA)
Surface analysis by mass spectrometry is an interesting research topic with plenty of applications. This type of analysis requires a previous sampling of the planar material and the introduction of the surface components on the mass spectrometer. As the readers know, there are different alternatives in this context, matrix-assisted laser desorption ionization (MALDI) being one of the most known. However, the mass spectrometric analysis of a surface can be also performed by direct contact liquid interfaces.(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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Highlighted articles (November 27th, 2015)

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We recommend the following articles that deal with different aspects related with sample preparation. 1. Application of graphitic sorbent for on-line microextraction of drugs in human plasma samples . Graphitic carbon has a great potential as sorbent since it may develop different interaction chemistries with target compounds. Commercial graphitic carbons like graphitized carbon black or porous graphitic carbon presents some disadvantages including a lack of mechanical stability or a high retention (almost irreversible) of some analytes. These shortcomings are faced in this article where a new carbon material is presented. The new material is based on the deposition of a graphitic carbon layer over an inert substrate like alumina. This combination increases the mechanical strength which is key for chromatographic uses. The material has been packed in a lab made microextraction in packed sorbent (MEPS) device and it has been applied for the extraction of ropivacaine and lidocaine f
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