MSACL 2019 EU Abstract

Evaluating the Stability of Breath During Storage in Thermal Desorption Tubes by Mass Spectrometry

Oscar Ayrton, Sophie Doran, Michael Hewitt, Ilaria Belluomo, George B. Hanna
Imperial College London

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Oscar Ayrton (Presenter) Imperial College London >> POSTER (PDF)

Presenter Bio: In 2011 I completed my undergraduate degree from Cambridge in Chemistry. In 2012 I spent 6 months carrying out an internship at a private healthcare supplier. In 2013 I completed my Postgraduate MSc in Forensic Sciences at King’s College London.
In May 2014 I started a role at the analytical science company LGC in a laboratory that carried out drug quality control on behalf of the Medicines and Healthcare products Regulatory Agency (MHRA).
In 2018 I decided I wanted to get more involved in non-routine research and in April 2018 started my current role as a Biomedical Research Officer at Imperial College London in the Professor Hanna VOC group. My responsibilities include laboratory management, instrument quality control, setting up the laboratory quality system, Biobank management and advising on technical aspects of research.

Relevant Financial Disclosures (within past 24 months) No relevant financial relationship(s) to disclose. Conflict mitigation NOT REQUIRED.

Introduction
The relationship between volatile organic compound (VOC) content in the breath and disease state is well established and so breath analysis has the potential to become a non-invasive early diagnostic tool. Direct sampling techniques such as proton transfer reaction mass spectrometry (PTR-MS) and selected ion flow tube mass spectrometry (SIFT-MS) have been used to probe differences in VOC profiles in clinical studies. Previous studies have used direct sampling techniques or breath collection in nalophan bags for VOC analysis. For large multi-centre studies the use of direct techniques or nalophan bags is inappropriate as samples will need to be stored on site, collected together and transported to the laboratory and may not be able to be analysed immediately, requiring further storage. A potential solution to this issue is to use thermal desorption (TD) tubes to store breath, transport to the laboratory and analyse at a later date. To validate this approach, a study to look at the deterioration of VOCs over time stored in thermal desorption tubes at a range of temperatures is being carried out.
Methods:
The Carbograph-Tenax TD tubes were conditioned as per manufacturer’s instructions then stored with air-tight brass caps on as blanks or loaded with a standard mixture of benzene, phenol, acetone, propanal, butanal and decanal, prepared by means of a permeation unit. The tubes were stored at a range of temperatures: -80°C, -20°C, +4°C, room temperature and +37°C. Desorption tubes were analysed at the start of the study (day zero), and then after 1, 3, 7, 14, 21 and 28 days. VOCs were analysed by a TD unit attached to a PTR-MS instrument with NO+ ionisation.
Results:
VOC concentrations were stable, although at 37° C acetone showed a slight deterioration after 28 days. This may be because it is the most volatile compound of the standard mixture and so it is the first to deteriorate.
Conclusion:
Results using the standard mixture are encouraging as there is no deterioration at room temperature after 28 days, indicating that TD tubes could potentially be stored without impacting on results. Further work includes expanding to breath to see the impact of the moisture in the matrix on storage and changing the ionisation mode to analyse different compounds.