SPME to evaluate the permeation profiles of human presence markers

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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 sense, human urine is usually considered as the matrix probe as it generates a wide range of potential biomarkers, some of them (up to 230) being volatile organic compounds. On the other hand, it is necessary to understand the production profile of the potential biomarkers as well as their interaction (adsorption) with the building materials, that is, their permeation profiles.

In a recent article, published in The Analyst, researchers from Austria, Poland and Greece have developed an interesting study of the permeation profile of 22 urine-borne compounds (2). For this purpose solid phase microextraction performed in a dedicated permeation chamber has been used in combination with gas chromatography-mass spectrometry. The effect of two different building materials, brick and concrete, on the permeation profiles of the potential biomarkers has been also evaluated.

The authors claim two main conclusions in the study. First of all, the generation of urine markers is not constant in time and the concentration profile depends directly on the chemical nature of the biomarker. Secondly, the building material modifies the concentration profile due to the interaction with the biomarker. In this sense, concrete presents a more intense adsorptive behavior. Among all the analyzed compounds, ketones can be considered the most promising biomarkers thanks to their high concentration and persistence over the time.

For more detailed information, readers are referred to the article where they will find a deeper discussion about the permeation profiles of the potential biomarkers. Moreover, they will find the description of the dedicated permeation chamber.

References:

(1) Earthquake hazards program. Link
(2) Permeation profiles of potential urine-borne biomarkers of human presence over brick and concrete. Link

Acknowledgement: The picture showed in this post has been obtained from http://www.freedigitalphotos.net/

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