Solid-liquid extraction in hard cap espresso machine

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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 cap type, as it has been demonstrated by the authors, can reach 19 bars. To allow the normal flowing of the extractant through the sample, the soil agglomeration has been avoided using a commercial dispersing agent and controlling the soil particles size.

The results obtained in combination with LC-FD are truly remarkable. Limits of detection in the low µg/Kg with good precision and exceptional accuracy, demonstrate the potential of the idea.

In addition to the analytical connotations, this article is a clear consequence of observing the daily reality with an open and scientific mind. In short, it teaches us that the scientific ideas may be closer to us than we think. Enjoy the reading of the full article in Analytical Chemistry (1).

Finally, we would like to thank Dr. Lasarte-Aragonés for suggesting this article for Microextraction Tech blog.

The editor

References:

(1) Hard cap espresso machines in Analytical Chemistry. What else?. Link to the article

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