Measurement of volatile organic compounds in exhaled breath as collected in evacuated electropolished canisters.
A set of three complementary analytical methods were developed specifically for exhaled breath as collected in evacuated stainless steel canisters using gas chromatographic-mass spectrometric detection. The first is a screening method to quantify the carbon dioxide component (generally at 4-5% concentration), the second method measures the very volatile high-level endogenous compounds [e.g. acetone and isoprene at 500-1000 parts per billion by volume (ppbv), methanol, ethanol, dimethylsulfide at 2-10 ppbv], and the third method is designed to measure trace-level environmental contaminants and other endogenous volatile organic compounds (VOCs) (sub-ppbv) in breath. The canister-based sample format allows all three methods to be applied to each individual sample for complete constituent characterization. Application of these methods is shown to be useful in the following ways: analysis of CO2 levels indicates the approximate quantity of alveolar breath collected (as opposed to whole breath) in a sample; levels of major endogenous compounds are shown to be influenced by physical activities and subsequent recovery periods; and environmental exposures to xenobiotic VOCs can be characterized by assessment of post-exposure breath elimination curves. The instrumentation and methodology are described and example chromatograms and quantitative data plots demonstrating the utility of the methods are presented.