A comparison of sorbent materials for offline TD-GC-MS breath analysis

A comparison of sorbent materials for offline TD-GC-MS breath analysis

Wilkinson M (1), White I (1), Nijsen T (2), Goodacre R (3), Fowler SJ (1)
1. Division of Infection, Immunity and Respiratory Medicine, University of Manchester, Manchester, UK
2. Philips Research, Philips, Eindhoven, Netherlands
3. School of Chemistry, University of Manchester, Manchester, UK


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Background: Offline analysis of breath samples by TD-GC-MS remains the gold standard for the detection of novel potential biomarkers in breath. The sensitivity of these systems is affected by a large range of confounding factors and the sorbent material used to capture and concentrate volatiles at the time of sampling is an important consideration when designing a study. 
Methods: One single bed sorbent (TenaxGR) and two dual bed sorbents (TenaxTA/Carbograph1TD (TA/1TD) and TenaxTA/Carbograph5TD (TA/5TD)) were. The hydrophilicity of each sorbent was assessed and optimal dry purge times were selected for 0.5 and 1 L sampling volumes. The recovery of 29 compounds loaded using high humidity gas was tested for each sorbent and compared to recovery when loaded using dry gas. Finally repeat breath samples were taken on the ReCIVA (Owlstone Cambridge) to validate the results of the previous experiments in a real breath sampling environment. 
Results: Dry purge times for all sorbents. Loading the standards in humid gas was shown to lead to reduced recovery of compounds. The breath results allowed discrimination between the sorbents using PC-DFA. Principally due to better retention of highly volatile species by TA/5TD and TA/1TD when compared to TenaxGR and the different background profiles between sorbents.
Conclusions: While it is important to try and capture the largest range of VOCs possible, making the use of stronger sorbent mixes such as TA/5TD desirable, consideration must be given to the high humidity of breath samples and the impact that this will have on the recovery of VOCs.




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