Importance of sorbent material selection for VOCs sampling: application on bacterial cultures and breath.

Importance of sorbent material selection for VOCs sampling: application on bacterial cultures and breath.

Authors: Flavio A. Franchina1; Delphine Zanella1; Pierre-Hugues Stefanuto1; Giorgia Purcaro2; Alison Burklund2; Marco Beccaria2; Jane E. Hill2; Jean-François Focant1.

Affiliations: 1Organic and Biological Analytical Chemistry Group, University of Liège, Belgium 
2Thayer School of Engineering at Dartmouth College, Hanover, USA




Bacterial volatile organic compounds (VOCs) have been considered as sensitive and specific biomarkers for bacterial phenotyping in both human biofluids (breath, blood, urine, etc.) and culture media. The possibility of using VOCs markers for bacterial identification would open a new frontier for developing more efficient diagnostic techniques of infections. Besides the biological differences in in vivo/in vitro environments, the importance of using the same sampling technique and sorbent phase is crucial for the translation and validation of biomarker discovery.  In the present contribution, GC×GC-MS was exploited to compare and evaluate different adsorption materials for thermal desorption tubes for VOCs sampling. Specifically, the following parameters were evaluated: sensitivity, selectivity, reproducibility and linear range. Five different adsorbent materials (Carbopack Y, X, B, Carboxen 1000 and Tenax), packed singularly or in combination, were tested on a standard mixture (15 compounds). The tubes packed with Tenax showed the best reproducibility (max 14% RSD) and sensitivity, with ~24 average fold increase compared to Carbopack Y+X+Carboxen 1000, which was second in terms of sensitivity.     The two better performing thermal desorption tubes, Tenax and Carbopack Y+X+Carboxen 1000, was also evaluated on E. coli, S. aureus, and P. aeruginosa cultures. Both tubes were able to discriminate between the 3 culture types, but improved sensitivity and reproducibility were obtained with Tenax tubes. A similar comparison on tube performances was carried out on breath samples.




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