Comment on 'influences of mixed expiratory sampling parameters on exhaled volatile organic compound concentrations'

Stimulated by reading the recent article (Thekedar et al 2011 J. Breath Res. 5 016001) we are constrained to comment on some essential aspects of the terminology, interpretation and analysis of proton transfer reaction mass spectrometry (PTR-MS) data therein in an attempt to provide suggestions that will allow more rigorous application of PTR-MS to breath research and other areas. Additionally, we comment on the sampling methodology and protocols used and suggest that such experiments are most useful when compound identification is reliable. Finally, we propose that the challenging problems of identification and quantification of trace breath biomarkers related to patho-physiological conditions rather than the details of breath sampling should now become the priority for further breath analysis research.