Microextraction Tech

The implementation of microextraction techniques in process laboratories usually depends on their automation degree. In reality, the use of too manual procedures is not practical when a large number of samples must be processed. In addition, manual workflows are labor intensive and prone to errors. This situation can be further complicated when risky samples, pretty common in bioanalysis, are handled. The potential of electromembrane extraction (EME) has been highlighted several times in Microextraction Tech blog. Among other advantages, EME is a rapid process thanks to the migration of the target compounds from the sample to the acceptor phase (through an appropriate supported liquid membrane) under an electrical voltage gradient. No doubt, the automation of EME and its hyphenation to chromatographic techniques would have a high impact in the field. Researchers from the universities of Copenhagen and Oslo have reported this year two interesting articles in this context. Earli...

Selectivity is a main issue in any analytical process. Many strategies can be proposed to achieve the highest value of this basic analytical property. Among them, the use of selective sorbents can be highlighted. There are several alternatives that can be used to synthesize them, being the molecular imprinting one of the most reported. The so-called molecularly imprinted polymers (MIP) are usually employed to selectively isolate and preconcentrate target compounds from the sample matrix. Despite their potential, the synthetic process is complex and it requires the use of the target molecule to create the sterically and electrically recognition site on the polymeric network. It has two main inconveniences: a) the cost of the analyte which is used as template and b) the need for a complete elimination of the analyte to avoid memory effects. These negative aspects are relevant which MIP are intended to be used in a purification technique where the cost of the procedure exponentially incr...

Electrospun fibres (EFs) have a great potential in microextraction techniques thanks to their advantageous characteristics. They are versatile as a relatively large number of different polymers, with different interaction chemistries, can be used as precursors. In addition, the use of mixtures of polymers as well as the introduction of nanoparticles in the fibrous network have extended the applicability and have improved their performance. Although EFs can be obtained in several formats (e.g as solid phase microextraction coatings), they can be easily fabricated as a mat of ordered or random fibers. These membranes present a high surface to volume ratio which is key for a rapid extraction kinetics. In some cases, EFs membranes can be used as filters where the sample flows through the polymeric network while the analytes are retained. In other cases, the membrane can be immersed into the sample and the analytes are transferred from the bulk solution to the sample thanks to the sample a...

Despite the importance of solid-liquid extraction in the analysis of solid materials, this technique has been scarcely discussed in this blog. This post aims to be an inflection point in this trend and we have selected a very interesting article for this purpose. The article has been published in Analytical Chemistry by our colleagues from Valencia (Spain) under the appealing title " Hard cap espresso machines in Analytical Chemistry. What else ?". In this study, the authors proposed the use of espresso machines and their hard caps as extractors for the isolation of polycyclic aromatic hydrocarbons from soil samples. The idea is simple and clever and it involves the introduction of the soil into commercial caps and its extraction, as a conventional coffee cap, in the espresso machine with slight modifications. To make the extraction feasible, an acetonitrile/water mixture, instead of pure water, is used as extractant. The extraction pressure, which depends on the ...