Reducing Background VOCs in Breath Samples

Published on 31 Mar 20, under Research focus

Collecting and analyzing volatile organic compounds (VOCs) on exhaled breath represents a powerful and versatile means to detect and monitor a wide range of diseases and biological effects. Breath collection can be completely non-invasive and can be applied for use with patients affected by a range of conditions including inflammation, respiratory diseases, liver and metabolic diseases as well as cancers. A growing body of evidence from around the world demonstrates the potential of techniques such as Breath Biopsy for early detection of diseases and precision medicine.

One of the breath collection challenges that Breath Biopsy® addresses is the presence of background VOCs in samples. Food, drink, flowers, cleaning products, pollution etc. are all sources of VOCs and the air in a room will always contain a broad selection of VOCs that have nothing to do with a patient’s health. Background VOCs add to the complexity of studying breath since each sample contains a combination of VOCs from biological and external environmental sources.

As an additional challenge, the selection of background VOCs is highly dependent on location. This means that collected breath samples often contain VOCs that are more related to location than to subject health and can be one reason for proposed breath biomarkers failing to pass validation. Many studies control for this by collecting all samples in the same room, but this isn’t a practical solution for large scale trials or eventual clinical applications.

We created the CASPER™ Portable Air Supply, part of the Breath Biopsy Collection Station, to reduce background VOC contamination in breath samples. CASPER combines a pump and filtration system, drawing in room air and removing VOCs. The air from CASPER is then supplied to the ReCIVA® Breath Collector ensuring that the air inhaled by each subject contains minimal and uniform background VOCs, limiting the impact of sampling location on the collected VOCs. The inclusion of CASPER in Breath Biopsy Collection Stations means you can have greater confidence that the VOCs in your samples come from your test subjects and not the air around them.

Comparison to Clean Air Supplies

Industrial air cleaners remove VOCs from the air, but producing clean air is a complex and expensive process and the required machinery isn’t portable. CASPER provides a more practical, economical and mobile solution while offering comparable reduction in background VOCs for breath collection.

We used the Breath Biopsy platform (gas chromatography mass spectrometry (GC-MS)) to analyze air produced by CASPER in comparison to industrial clean air and ambient air samples.

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Figure 1: CASPER Portable Air Supply reduces ambient VOCs to an extent comparable to industrial clean air and statistically comparable to unused sorbent tubes. Data derived from total GC-MS spectrograph areas normalised against spectra generated from unused tubes. P-values show results of pairwise t-test comparisons. P-value for comparison to unused tubes are shown directly above each bar.

This illustrates CASPER’s ability to effectively remove a broad-spectrum of VOCs from ambient air, while remaining suitable for use in a range of breath collection situations.

Removing Known Test Compounds from the Air

We’ve also tested CASPER by introducing increased levels of selected VOCs into the air. We used a combination of essential oils to add VOCs to the air in a room. Samples of the air in the room were collected using the ReCIVA Breath Sampler. We also collected samples of the air after it had been processed by CASPER. The VOCs from both sets of samples were analysed on the Breath Biopsy platform. 

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Figure 2: Ambient VOCs collected in rooms spiked with a non-standardized quantity of essential oils, with and without the use of CASPER

Thorough Quality Control at All Stages

Appropriate and thorough quality control is critical to our ability to provide high quality breath analysis for our customers. Across all Breath Biopsy studies, we collect and analyze air from CASPER collected on sorbent tubes. As a baseline, we also analyze comparable unused sorbent tubes. The results of these analyses are compared to ensure that all CASPER devices provide reliable background VOC reduction across every Breath Biopsy study.

Non-invasive breath analysis represents an unparalleled opportunity for the advancement of disease detection and precision medicine. Breath Biopsy offers world-leading breath collection and analysis capabilities to support your biomarker research. With performance that parallels industrial air cleaners, CASPER represents the most suitable and widely applicable solution to the challenge of background VOCs in breath collection. CASPER uses a standard power supply and draws air from its surroundings, it is portable and has easy-change filter cartridges each of which is suitable for up to 250 hours of use making it suitable in almost any clinical setting. To find out more about CASPER and how Breath Biopsy can support your research, get in touch.

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