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Title: Analysis of human breath samples using a modified thermal desorption: gas chromatography electrospray ionization interface
Authors: Reynolds, James C.
Jimoh, Modupe A.
Guallar-Hoyas, Cristina
Creaser, Colin S.
Siddiqui, Salman
Thomas, C.L. Paul
Keywords: Secondary electrospray ionisation
Thermal desorption
Mass spectometry
Issue Date: 2014
Publisher: © IOP Publishing Ltd
Citation: REYNOLDS, J.C. ... et al, 2014. Analysis of human breath samples using a modified thermal desorption: gas chromatography electrospray ionization interface. Journal of Breath Research, 8 (3), 037105.
Abstract: A two-stage thermal desorption/secondary electrospray ionization/time-of-flight mass spectrometry for faster targeted breath profiling has been studied. A new secondary electrospray ionization (SESI) source was devised to constrain the thermal desorption plume and promote efficient mixing in the ionization region. Further, a chromatographic pre-separation stage was introduced to suppress interferences from siloxanes associated with thermal desorption profiles of exhaled breath samples. In vitro tests with 5-nonanone indicated an increased sensitivity and a lowered limit-of-detection, both by a factor of ~4, the latter to an on-trap mass of 14.3 ng, equivalent to a sampled breath concentration of 967 pptv. Analysis of the mass spectrometric responses from 20 breath samples acquired sequentially from a single participant indicated enhanced reproducibility (reduced relative standard deviations (RSD) for 5-nonanone, benzaldehyde and 2-butanone were 28 %, 16% and 14% respectively. The corresponding values for an open SESI source were that 5-nonanone was not detected, with %RSD of 39% for benzaldehyde and 31% for 2-butanone). The constrained source with chromatographic pre-separation resulted in an increase in the number of detectable volatile organic compounds (VOCs) from 260 mass spectral peaks with an open SESI source to 541 peaks with the constrained source with pre-separation. Most of the observed VOCs were present at trace levels, at less than 2.5% of the intensity of the base peak. Seventeen 2.5 dm3 distal breath samples were collected from asthma patients and healthy controls respectively, and subjected to comparative high-throughput screening using thermal desorption/SESI/time-of-flight mass spectrometry (TD-SESI-ToFMS). Breath metabolites were detected by using a background siloxane ion (hexamethylcyclotrisiloxane m/z 223.0642) as an internal lockmass. Eleven breath metabolites were selected from the breath research literature and successfully targeted. These data reinforce the proposition that TD-SESI-MS has potential for development as a rapid screening method for disease stratification and targeted metabolism profiling
Description: This definitive published version of this paper is available from: http://dx.doi.org/10.1088/1752-7155/8/3/037105
Sponsor: The authors gratefully acknowledge the Daphne Jackson Trust and the sponsorship of EPSRC and Loughborough University for the support to MAJ. CG-H was supported jointly by funding from Astra Zeneca and Loughborough University. The in-clinic studies were supported by the National Institute for Health Research (NIHR) Leicester Respiratory Biomedical Research Unit.
Version: Accepted for publication
DOI: 10.1088/1752-7155/8/3/037105
URI: https://dspace.lboro.ac.uk/2134/16247
Publisher Link: http://dx.doi.org/10.1088/1752-7155/8/3/037105
ISSN: 1752-7155
Appears in Collections:Published Articles (Chemistry)

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