Mass Spectrometry Applied to Large-Scale Multi-Centre Clinical Project in Breath Research Ilaria Belluomo (Presenter) Imperial College London Presenter Bio: I am currently a post-doc scientist at the Surgery and Cancer division of the Imperial College London in the team of Professor George Hanna. The main interest of the research team is volatile organic compounds analysis in human breath and biofluids with different mass spectrometry techniques. Since few months, I am the senior scientist and I am directly responsible of the scientific and organizational management of the whole team. Before starting my postdoc in London, I have been working in Bologna (Italy) and in Bordeaux (France). My PhD has been carried out between these two countries, as part of the international program “Doctor Europaeus”. Clinical applications of mass spectrometry have always been the common thread in my entire career.

Authors: Belluomo I (1), Woodfield G (1,2), Waller A (1), Doran S (1,2), Lin G (1), Ayrton O (1), Romano A (1), Hanna GB (1,2)
1) Imperial College London 2) Imperial College Healthcare NHS Trust

Non-invasive and rapid diagnostic testing, such as breath testing, is the future of diagnostic medicine. We are establishing a workflow for a multi-centre large-scale clinical project for the diagnosis of colorectal cancer. This involves analysis of breath samples with two different mass spectrometry platforms, requiring reliability and a strong quality control system. The use of two different but complementary technologies and the three levels of quality control for this large-scale screening increased sensitivity, specificity and reliability of the results. Thanks to our multi-instrument platform and three different levels of quality control, we have an accurate, specific and sensitive method for determining volatile organic compounds profile in human breath.

Introduction

Non-invasive and rapid diagnostic testing, such as breath testing, is the future of diagnostic medicine1. Exhaled breath contains numerous trace gas metabolites, volatile organic compounds (VOCs), which potentially reflect all the biochemical processes acting in the body2. Due to the complex composition and the very low levels of VOCs (almost all are parts per billion, ppb), the techniques used to analyse breath must be highly sensitive and specific3. Mass spectrometry nowadays is one of the most innovative techniques in analytical chemistry, in continuous evolution, which allows high specificity and sensitivity, in a short analysis time. We are establishing a workflow for a multi-centre large-scale clinical project for the diagnosis of colorectal cancer. This involves analysis of breath samples with two different mass spectrometry platforms, requiring reliability and a strong quality control system.

Methods

Breath samples are analysed with proton transfer mass spectrometry (PTR-MS) and gas chromatography mass spectrometry (GC-MS). Three levels of quality control were established: instrument quality control, quantification quality control and single sample quality control. We developed the single sample quality control system by calculating a threshold for reference compounds always present in human breath. In the first part of the study, 400 breath samples were collected in thermal desorption tubes from patients in four London hospitals over six months and analysed at the Surgery division of Imperial College London.

Results

The use of two different but complementary technologies and the three levels of quality control for this large-scale screening increased sensitivity, specificity and reliability of the results. The single sample quality control system, in particular, provided evidence of some limitations of using thermal desorption tubes and allowed appropriate removal of unreliable samples.

Conclusions & Discussion

Breath is a complex biological matrix that represents the future of non-invasive diagnostic testing. Thanks to our multi-instrument mass spectrometry platform and three different levels of quality control we have an accurate, specific and sensitive method for determining the VOC profile in human breath.

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2. Volatile metabolites in the exhaled breath of healthy volunteers: their levels and distributions. Smith D, Turner C, Spaněl P. Journal of Breath Research 2007 Sep;1(1):014004.

3. A longitudinal study of ammonia, acetone and propanol in the exhaled breath of 30 subjects using selected ion flow tube mass spectrometry, SIFT-MS Turner C, Spanel P, Smith D. Physiological Measurement 2006 Apr;27(4):321-37.