Human breath analysis: methods for sample collection and reduction of localized background effects

Abstract

Solid-phase microextraction (SPME) was applied, in conjunction with gas chromatography-mass spectrometry, to the analysis of volatile organic compounds (VOCs) in human breath samples without requiring exhaled breath condensate collection. A new procedure, exhaled breath vapor (EBV) collection, involving the active sampling and preconcentration of a breath sample with a SPME fiber fitted inside a modified commercial breath-collection device, the RTube, is described. Immediately after sample collection, compounds are desorbed from the SPME fiber at 250 degrees C in the GC-MS injector. Experiments were performed using EBV collected at -80 degrees C and at room temperature, and the results compared to the traditional method of collecting exhaled breath condensate at -80 degrees C followed by passive SPME sampling of the collected condensate. Methods are compared in terms of portability, ease-of-use, speed of analysis, and detection limits. The need for a clean air supply for the study subjects is demonstrated using several localized sources of VOC contaminants including nail polish, lemonade, and gasoline. Various simple methods to supply clean inhaled air to a subject are presented. Chemical exposures are used to demonstrate the importance of providing cleaned air (organic vapor respirator) or an external air source (tubing stretched to a separate room). These techniques allow for facile data interpretation by minimizing background contaminants. It is demonstrated herein that this active SPME breath-sampling device provides advantages in the forms of faster sample collection and data analysis, apparatus portability and avoidance of power or cooling requirements, and performance for sample collection in a contaminated environment.

Analytical challenges in breath analysis and its application to exposure monitoring

“…EBC contains both volatiles and non-volatiles, and these must be recognized as separate entities with different properties [34]. But, it has been found that conventional EBC-collection methods (e.g., Rtube at -80ºC) yield significantly lower sensitivity in the analysis of VOCs than specific EBV-concentration methodologies {e.g., solid-phase microextraction (SPME) [35]}. When VOCs are the analytes of interest, EBV sampling is preferred.…”

Biomarkers in asthma and allergic rhinitis

“…However, an ATS/ERS task force addressed several issues resulting in novel EBC guidelines [85]. Several collectors and condensers are currently available [86][87][88][89][90]. All devices are easy to use and subsequent exhaled breath collection can be simply obtained from both young and elderly individuals.…”

Influence of ambient air on NMR-based metabolomics of exhaled breath condensates

“…This method is currently applied in MS breath analysis by measuring the metabolic concentration in volatiles (also in EBCs) and subtracting (filtering) the analytes from room air. Details about room air measurement have been previously reported [14]. A similar approach cannot be easily translated to NMR-based metabolomic data.…”