SIFT-MS Analysis of Nose-Exhaled Breath; Mouth Contamination and the Influence of Exercise

The value of selected ion flow tube mass spectrometry, SIFT-MS, for the sampling and analysis of trace metabolites in both mouth-exhaled and nose-exhaled breath is discussed, and the latter is shown to circumvent oral contamination. Results of experiments are described in which increased levels of ammonia and ethanol deliberately generated in the oral cavity are clearly registered in mouth-exhaled breath but not in nose-exhaled breath. The value of the sampling methods that are used for the analysis of trace metabolites in both mouth-exhaled and nose-exhaled breath with selected ion flow tube mass spectrometry, SIFT-MS, is discussed, and their importance as a means to provide concentrations of truly endogenous compounds by circumventing their oral contamination is demonstrated. Further to this, data are presented on the direct analysis by SIFT-MS of several compounds in the nose-exhaled breath of eight healthy volunteers during exercise on a stationary bicycle. Of note are the data on breath isoprene, which is seen to increase during exercise above the respective resting levels for all eight volunteers by a factor of 2 or 3 times, this being in accordance with previous observations. Taken together, the results of this study show the value and simplicity of direct analysis of nose-exhaled breath by SIFT-MS, which can provide immediate results to the clinician and sports physiologists with no pain or discomfort to the volunteer or patient.