thank you for initiating this very interesting and important discussion on RG. In fact, ther are a few relevant articles available in the literature which might help you in your analysis. For example, please have a look at the following potentially useful research papers:
Cardiovascular Biomarkers In Exhaled Breath
Article Cardiovascular Biomarkers In Exhaled Breath
Urinary volatile organic compounds as potential biomarkers for renal cell carcinoma
Article Urinary volatile organic compounds as potential biomarkers f...
Unfortunately these two articles have not yet been posted as public full texts on RG. However, in both cases some of the authors have RG profiles. So it should easily be possible to request the full texts directly from the authors via RG (provided that they are of interest to you).
Good luck with your work and best wishes, Frank Edelmann