Microextraction Tech

Carbon nanotubes sponges are three dimensional structures formed by the random self-assembly of these nanostructures during their synthesis. They are produced by the classical chemical vapor deposition method simply using special catalysts like ferrocene. The structure of an sponge can be observed in Figure 1A which shows a scanning electron micrograph of the bulk material. A closer view (Figure 1B) reveals how the nanostructures are interconnected(1). The sponges are characterized by a high superficial area (up to 100 m2/g), high porosity (derived from the 3D structure) and low density. From the chemical point of view they are superhydrophobic, property that has been exploited in some applications, such as the recovery of oil from water or the treatment of environmental waters. Figure 1. SEM micrographs of carbon nanotubes sponges at two magnifications. Reproduced from reference 1 Researchers from the Shandong Academy of Sciences and the Wuhan University of Technology have

Microextraction techniques have evolved from classical extraction procedures following three main trends, namely: miniaturization, simplification and automation, which have not received a similar attention in the last decades. In fact, simplification and miniaturization (in different degrees) are almost inherent to the majority of the new approaches while automation is, in some cases, considered in a lesser extent. However, all these facets are capital, especially if we consider the new demands of analytical information. The modern analytical platforms will have to process a larger number of samples providing information even faster and cheaper. It seems obvious that in this scenario, the previous trends should go a step further. Microfluidic system can answer to these new demands. On the one hand, they allow the miniaturization of the analytical procedures reducing the requirements of sample and extractant volumes to the microliter range. On the other hand, these systems can be

Single drop microextraction (SDME), the first liquid phase microextraction technique proposed, is a simple approach consisting of the extraction of the target analytes from the sample into a small drop of extractant. The characteristics of the drop, specially its chemical nature and mechanical stability, are key factors to guarantee the success of the extraction. Its chemical composition defines the affinity towards the target analytes which are, in fact, extracted depending on their solubility. The mechanical stability of the drop during the extraction is critical since the drop detachment would ruin the extraction. The drop volume and handling increase the probability of that detachment. Researchers from Ukraine and Slovak Republic have already published in Analytical Chemistry journal a nice contribution to SDME that overcomes this shortcoming(1). In this case, an optical probe is used as the drop holder in such a way that the continuous UV-Vis monitoring of the drop is achieve