Moving miniaturization a step forward

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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 completely automated and even integrated with the analytical instruments. This post deals with a recent contribution of microfluidic microextraction just published in Journal of Separation Science. In this article, Bagheri et al. have designed a chip that miniaturizes solid phase extraction in a simple microchannel. The microchannel, which is previously excavated in a silicone rubber plate by using a carbon dioxide laser, presents dimensions (width and depth) in the intermediate micrometer range. That means that volumes in the microliter range can be easily processed. In addition, the channel is coated with an extracting polymer,  polyaniline (PANI), which allows the isolation of the target analytes.

Once prepared, the chip works in a simple manner. In a first step, the sample containing the analytes (atrazine, ametryne and terbutryn) is passed through the channel, the analytes being retained. Secondly, the channel is washed and dried before the final elution, performed with a few microliters of solvents that are directly driven to the gas chromatograph injector. Exceptional sensitivity and precision are obtained in this approach.

We recommend you the reading of the article. You will find there the fabrication of the microchannel, the optimization of the extraction and the complete validation of the analytical application.

Reference:

(1) H. Bagheri, M. Allahdadlalouni, C. Zamani. Toward a comprehensive microextraction/determination unit: A chip silicon rubber polyaniline-based system and its direct coupling with gas chromatography and mass spectrometry, J. Sep. Sci. DOI: 10.1002/jssc.201600500 Link to the article

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