Microextraction Tech

Information about drug distribution after intake in a certain tissue is of relevance as it provides useful information for the development of novel medicines. Conventional homogenization methods are not applicable in this context as they provide a qualitative information about the drug present in the analyzed samples. However, data about the spatial distribution and the ability of the drug to cross the cellular barrier is usually missing. To overcome this drawback, Swales and coworkers have studied the drug distribution in brain tissue using liquid extraction surface analysis combined to mass spectrometry (LESA-MS). LESA-MS is a surface sampling technique that combines liquid extraction from the surface of tissue sections with mass spectrometry. The authors use mass spectrometric imaging (MSI) to build an image of xenobiotic and endogenous compound distribution to asses drug brain barrier penetration. LESA-MSI was useful to obtain the map distribution of poorly penetrative compoun...

The analysis of ancient documents, pictures, archeological pieces and related added-value samples is a challenging issue for any analytical chemist. The unique character of the samples and the priceless values of most of them require the sampling of a very small quantity to obtain as much information as possible. Undoubtedly, the direct analysis or the use of non destructive analytical techniques must be the first option for the researchers. But not the only one!! Our loved microextraction techniques could play a relevant role in this scientific field as they are able to maximize the amount of information obtained from a very low sample amount. Recently, The Analyst journal has published a research carried out by our colleagues from the University of North Texas dealing with the potential of direct analyte-probed nanoextraction (DAPNe) coupled to different instrumental techniques for the determination of the authenticity of documents (1). The ink used for writing the manuscript is...

Direct coupling of microextraction techniques and ambient ionization mass spectrometry opens a door to rapid, selective and sensitive analyses that are quite attractive in the bioanalytical field. The use of nanoparticles (NPs) in this combination may be problematic since they are not fully compatible with MS although they have a great potential as sorbent in microextraction techniques. In fact, these NPs may be blown during the ionization step causing the entering of this material in the spectrometer. Prof. Yu-Qi Feng and coworkers have recently proposed the use of magnetic NPs (MNPs) for this arrangement avoiding the previously mentioned shortcoming. The extraction protocol follows the typical workflow of a dispersive solid phase extraction (DSPE). In short, the MNPs are dispersed into the sample to favor the interaction/isolation of the analytes. Afterwards, they are cleaned-up with an appropriate solvent and finally recovered in a special capillary for instrumental analysis. T...

Design and fabricate your own extraction devices in a cheap and rapid way. This is the main conclusion that we can infer after reading an article recently accepted for publication in Analytical Chemistry. This dream has come true by our colleagues form the National Tsing-Hua University at Taiwan (1). They have designed a solid phase extraction device which has been finally fabricated in acrylate using a 3D printer. The fabrication time (approximately 38 min) and the cost of each unit (US$ 1.5) are really motivating. The extraction device consists of a microfluidic channel where cuboids of defined dimensions are printed on surface to increase the superficial area and thus the extraction kinetics. The device presents a high permeability, it allows the use of high sample flow rates (essential to pass larger sample volumes allowing high preconcentration factors) and it is easy to regenerate. In addition, it can be easily adapted to flow systems as it can work with low-pressure pumping...

Membranes can be used for different purposes in Analytical Chemistry. In the extraction context, they permit the development of several liquid-liquid extraction techniques such as dialysis, osmosis, among others. Also, they can provide an additional enhancement of the selectivity by the direct selection of the pore size. They are also commercialized in different formats (planar, tubular) and polarities in such a way that they can be applied to almost any analyte-sample binomial. In liquid phase microextraction, membranes have been used under the 2 phases and 3 phases formats depending on the number, nature and role played by the different liquid phases involved. In order to favor the kinetic of the whole process the continuous agitation of the system is recommended to accelerate the diffusive transport of the target compounds in both the donor and acceptor phases reducing the thickness of the diffusion layer near the membrane. Prof. Dr March and Prof. Dr. Cerdá have recently pro...

The potential of ionic liquids (ILs) in the microextraction context is beyond any doubt. ILs, especially those that are liquid at room temperature (RTILs), present a negligible vapour pressure (attractive in HS-SDME), tuneable solubility in water (interesting in in-situ solvent formation technique) and they may be tailored to extract target analytes by the proper selection of the forming ions. RTIL have been extensively used in DLLME for these reasons, its recovery after extraction, being usually developed by centrifugation thanks to their higher density than water. However, this centrifugation step is time-consuming and several alternatives like in-syringe DLLME have been proposed to avoid it. Magnetic materials present a clear advantage over other materials in dispersive procedures as they can be recovered from the bulk solution using an external magnet. The combination of magnetic materials/ionic liquids has been studied from different approaches. For example, ILs can be used t...

Today, we focus the attention on an interesting article recently published in Journal of Chromatography A by researchers from the University of Tasmania at Australia. As our readers well known, electrodriven liquid microextraction techniques present a high efficiency for the extraction of charged analytes. In those techniques, the analytes migrate from the sample to the acceptor phase as a consequence of the voltage gradient established between both phases. In the off-line modes, the involved phases are often physically separated by an organic phase or a polymeric membrane impregnated with an appropriate organic solvent. Our colleagues have proposed a novel configuration that permits the development of the extraction procedure without any physical barrier between phases (1). The device consists of a 20 µL micropipette (a microtube with length of 6.4 cm and inner diameter of 0.3 mm) where the acceptor phase is located. The upper part of the microtube is introduced into a syringe th...