Microextraction Tech

We highlight today an article that describes the combination of laser desorption and solid phase microextraction (SPME) for the analysis of solid samples. The article has been published in Rapid Communications in Mass Spectrometry under the title " Laser desorption sample transfer for gas chromatography/mass spectrometry" (1) . It is not necessary to describe the potential of SPME since it is a well established technique in almost every analytical laboratory. Despite its potential, SPME is the focus of an intense research and its direct combination with mass spectrometry (MS) or its in-vivo applications are strongly remarkable. Our colleagues, from the Louisiana State University, have proposed an innovative approach that allows the isolation of target compounds from solid samples followed by their preconcentration in a conventional SPME fiber. The manifold proposed is quite simple. First of all, the sample (solid or liquid) is deposited in a metal target. A laser radiati...

Nucleic acids have several practical applications in Analytical Sciences as they can be used as biorecognition molecules (e.g. aptamer) in the design of sensors and even extraction phases. However, this post deals with those methods that are aimed to determining nucleic acids in samples of different origin (usually biosamples). Among these applications, we can highlight paternity tests, the study of genetic diseases, the identification of the virus or bacteria behind an infection or the certification of the origin of a meat in a processed food. Whatever the application is. the extraction of nucleic acids of the system under study is the initial (and usually) critical step. The conventional extraction procedure, which is based on the use of silica particles as extractant, involves several steps like extraction or clean-up that makes the process tedious, especially if we consider that the particles should be separated from the sample or washing solutions by centrifugation. The use o...

The usefulness of molecularly imprinted polymers is unquestionable. They have been extensively used for the selective extraction of different families of compounds in a wide variety of samples. The main problem associated to these sorbents is the impossibility to ensure that a high percentage of the recognition sites are available for analyte interaction as they can be embebed into the polymeric structure. These attractive solids have not been excluded from the nanometric approach. In this sense, a synergic combination of the selectivity of the imprinting process and nanometric dimension is achieved. The easiest way to obtain nanoMips is by using a conventional nanoparticle (NP) as the core whose surface is covered by the polymeric phase with recognition sites. Usually, magnetic NPs are the preferred option because they also implements a clear simplification of the extraction process as they are isolated by means of an external magnet. However, their preparation can be a little be...

The extraction of polar compounds from aqueous matrices is not a easy process due to the high solubility of these compounds into the sample that weakens the interactions with the extractant. Polymeric phases, comprising different monomer in their structure that may establish polar interactions and even ionic, have been widely used to solve this problem. Although there are some commercially available phases, the development of novel ones as well as the design of formats different than the conventional particle-packed column one are attractive research lines. In this context, the use of polymer mats synthesized by electro-spinning allows the fabrication of extraction disks that have special properties like high surface to volume ratio. In addition, they permit the continuous flow of the sample through the extractant phase increasing the sample throughput. Polypyrrole (PPy) coated nylon fibers have been recently proposed as sorbent for the extraction of azo dyes, which are compound...

Mercury is a well known toxicant with different exposure sources. Although its use on medical products is banned in many countries, other sources like environmental pollution or contaminated food still exist. Professor Bin Hu and co-workers have been recently researched how Hg species are distributed and even modified in cell cultures [1]. In their own words, this type of research is of paramount importance in order to fully understand the toxicity but also the cell protection mechanisms. The toxicological application is, in itself, interesting but the tools used in this research makes it attractive to "microextracters". This study has come up several challenges related to cell culture studies. First of all, in this field the sample volume is usually limited so miniaturized instrumental techniques are required. In addition, the inherent nature of biosamples (complex matrices and low target concentrations) further complicate the situation. Our colleagues have on-line comb...