Variation of volatile organic compound levels within ambient room air and its impact upon the standardisation of breath sampling

Abstract

The interest around analysis of volatile organic compounds (VOCs) within breath has increased in the last two decades. Uncertainty remains around standardisation of sampling and whether VOCs within room air can influence breath VOC profiles. To assess the abundance of VOCs within room air in common breath sampling locations within a hospital setting and whether this influences the composition of breath. A secondary objective is to investigate diurnal variation in room air VOCs. Room air was collected using a sampling pump and thermal desorption (TD) tubes in the morning and afternoon from five locations. Breath samples were collected in the morning only. TD tubes were analysed using gas chromatography coupled with time-of-flight mass spectrometry (GC-TOF-MS). A total of 113 VOCs were identified from the collected samples. Multivariate analysis demonstrated clear separation between breath and room air. Room air composition changed throughout the day and different locations were characterized by specific VOCs, which were not influencing breath profiles. Breath did not demonstrate separation based on location, suggesting that sampling can be performed across different locations without affecting results.

Effects of a Volatile Organic Compound Filter on Breath Profiles Measured by Secondary Electrospray High-Resolution Mass Spectrometry

“…Most ambient air contaminants were only found at concentrations lower than 3 µg m −3 in their GC-MS data set, and they concluded that it was unlikely that the detected compounds with higher intensities were originating from the room air. In contrast to most other studies, Hewitt et al assessed the influence of different clinical sampling environments on breath data and did not find a significant impact, concluding that the sampling location and varying VOC levels in room air do not affect GC-MS breath measurements [27].…”

Progress and challenges of developing volatile metabolites from exhaled breath as a biomarker platform

“…Background correction techniques can be undertaken via the calculation of an alveolar gradient that directly compares signal strength in breath to background samples, simultaneous monitoring of inhaled and exhaled breath fractions, and using a lung washout with synthetic air to identify background VOCs (Hewitt et al, 2022 ; Maurer et al, 2014 ; Phillips, 1997 ; Schubert et al, 2005 ; Spaněl et al, 2013 ; Westhoff et al, 2022 ). A common method is collecting the ambient air in the same location where breath sampling is being performed, but this will not sample VOCs that originate from the sampling equipment.…”

Global Urinary Volatolomics with (GC×)GC-TOF-MS

“… 8 Orthogonal partial least-squares discriminant analysis (OPLS-DA) and PCA were performed with SIMCA 17 (Sartorius, Malmö, Sweden). The variable importance projection (VIP) score was used to select the features with the highest discrimination potential; 9 VIP-score > 1.35 was considered relevant for group separation. Permutation testing and CV-ANOVA were used to validate the OPLS-DA model.…”