Highlighted articles (November 12, 2014)

By -

We recommend the following articles that deal with different aspects related to sample preparation.

1. Development of combined salt- and air-assisted liquid–liquid microextraction as a novel sample preparation technique. Air assisted liquid-liquid microextraction is an interesting technique that uses air to assist the dispersion of the extractant solvent into the sample. It is usually performed by adding a small volume of extractant to the sample, the resulting mixture being sucked several times by a glass syringe. The process generates an efficient dispersion of the solvent and a final centrifugation is required to recover the acceptor phase for its final analysis. In this article, the authors face up the phases separation using a gas stream to break the emulsion and to recover a low volume of organic solvent (typically 10 µL). This proposal has been evaluated for the determination of β-naphtol, naphthalene and anthracene in water and wastewater. This article merits attention and you can read it freely for the next few weeks at this link.


2. Aptamer functionalized SPME–LC- tamdem MS for selective enrichment and determination of thrombin. Aptamers, which are nucleic acids or peptides that can bind target molecules with high affinity and specificity, are promising materials in Analytical Chemistry in general and in the microextraction filed in particular. Prof. Pawliszyn group has already proposed the use of aptamers as selective receptors in solid phase microextraction, using the determination of thrombin in serum as proof-of-concept. A stainless steel wire is coated by electrospinning with a polymeric mat of poly(acrylonitrile-co-maleic acid). The monomer composition and ratio defines the stability of the coating and its hydrophilicity, the latter aspect being essential for the immobilization of the aptamer. The resulting fiber demonstrated high selectivity towards the analyte when it is compared with other potential interferents like prothrombin, hemoglobin, cytochrome C and human serum albumin. Although the extraction capacity of the fiber resulted to be low in plasma samples, this problem can be avoided diluting the sample. This article presents a powerful combination and you can read it at this link.


3. A needle extraction utilizing a molecularly imprinted-sol–gel xerogel for on-line microextraction of the lung cancer biomarker bilirubin from plasma and urine samples. Dr. M. Abdel-Rehim and collaborators have already presented an interesting extraction unit for the selective extraction of bilirubin from plasma and urine samples. The unit consists of a needle whose inner surface is coated with a thin film of molecularly imprinted xerogel synthesized by sol-gel reaction of 3-(propylmethacrylate) trimethoxysilane. The new coating presents recognition potential when it is compared with the non-imprinted polymer. In addition, it can be reused up to 100 times with a negligible effect on the extraction performance. Read this article at this link.

Comments

Post a Comment

Popular posts from this blog

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

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

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