Microextraction Tech

Polymeric frits are employed in solid phase extraction to confine the sorbent in the cartridge avoiding it losses during the extraction procedure and to filter the sample avoiding the clogging of the cartridge due to the potential particulate matter present in the sample. Taking advantage of their organic nature -they are usually built with polyethylene- polymeric frits can be used as active sorbent allowing the retention of non polar analytes. Moreover, polymeric frits have been recently proposed as support for the synthesis of monolithic material (1) or molecularly imprinted polymers (2) for extraction purposes. Stir frit microextraction In a recent article, accepted for publication in Journal of Chromatography A, researchers from the University of Cordoba at Spain have proposed the use of polyethylene frits in the so-called stir frit microextraction technique (3). The new technique combines the extraction capability of this polymeric material with the stirring element, an ...

Carbon nanotubes reinforced hollow fiber microextraction (HF-SLPM) was proposed for the first time by Es´haghi et al. in 2010 (1). The original technique consisted of a multi-phase system where the aqueous donor and acceptor phases were separated by a polymeric membrane with a dispersion of carbon nanotubes in 1-octanol immobilized in its pores. The pH gradient established at both sides of the reinforced hollow membrane allowed the extraction of the target analytes. Due to its multiphase nature,  HF-SLPM  involves a selectivity enhancement compared to traditional hollow fiber liquid phase microextraction. Diethylstilbestrol The direct immobilization of carbon nanotubes (CNTs) in the pores of a polypropylene hollow fiber have been recently proposed by researchers from the Chinese Academy of Sciences of Beijing at China (2), for the isolation and preconcentration of diethylstilbestrol from milk. Diethylstilbestrol is a steroid hormone used for animal growth and it pre...

In the last decade, earthquakes have hit throughout the globe producing over 200.000 deaths (1). The effect of an earthquake depends  not only  on its size but also on the vulnerability of the buildings and infrastructure. In fact, a considerable percentage of deaths occur as a consequence of the building collapsing. In this context, the location of trapped victims becomes critical since their survival rate diminishes exponentially over the time. This location is usually performed by expert trained dogs as canine can analyzed large areas with high sensitivity. However, in the last years different instrumental techniques, such as ion mobility spectrometry (IMS), have been evaluated as alternative or complementary tools to canine work. In order to develop an efficient instrumental technique for the detection of human presence, two main aspects have to be considered. On the one hand, the selection of the biomarkers, as well as their biological source, is essential. In this s...

The efficient dispersion of the extracting phase into the sample is a useful strategy to enhance the kinetic of a given extraction technique. The dispersion enhances the contact area between phases making easier the transference of the target analytes across the interface. Dispersive procedures have been exploited both in the liquid and solid (micro)extraction techniques, being dispersive liquid-liquid microextraction (DLLME) a preeminent example. In DLLME, the dispersion of the extractant can be assisted chemically, by using a disperser solvent or surfactants, or applying an external energy source like ultrasounds. In a recent article, accepted for publication in Talanta, aerosol phase extraction (APE) has been proposed for the first time as an alternative to these conventional approaches (1). In APE the sample is nebulized by an inert gas into the extracting phase in the form of very small drops. APE presents two very positive aspects which must be highlighted. On the one han...

Stir cake sorptive extraction (SCSE) was proposed in 2011 by researchers from the Xiamen University at China as an alternative to classic stir bar sorptive extraction.(1) The novel extraction technique is especially useful when monolithic polymers, characterized by their low mechanical stability, are employed as extracting phases. In SCSE a disk of monolithic material is introduced in a dedicated device in order to protect it from cracking due to the friction with the extraction vessel walls. The device also allows the stirring of the solution, thanks to a metallic wire, enhancing the analytes transference from the bulk solution to the extracting phase. In the first application, the efficient extraction of steroid hormones from milk was achieved using poly(vinylimidazole-divinylbenzene) monolithic with a low effect of the sample matrix (it was not required to remove fat and proteins). In a recent article, accepted for publication in Journal of Chromatography A, the same research ...

Single drop microextraction (SDME), which was described in the middle 90´s, is an effective extraction technique which comprises isolation and preconcentration in one step, allowing the direct injection of the extracts in different analytical instruments. In SDME, a small volume of extractant is aspirated in a microsyringe which is introduced in the extraction vessel where the sample is located. A small drop of extractant, in the range of 1-5 µL, is finally exposed to the sample (direct immersion mode) or to its headspace (headspace mode) in order to extract the target analytes. After the extraction, the drop is retracted into the microsyringe which will be finally transferred to the appropriate analytical instrument. In the usual situation, the extractant is an organic solvent with suitable properties. In this way, the solvent should present a high affinity towards the analytes in order to isolate them from the sample matrix. Moreover, the organic solvent should present a low vo...