Limonene as a breath biomarker for liver diseases

Several publications investigating breath biomarkers for liver diseases have now reported limonene as a potential option for test development. Limonene is exogenous and so it can be administered before breath collection to provide a high contrast signal, this is the premise of the EVOC Probe approach.

Take a look at Ferrandino et al. for more information: https://www.owlstonemedical.com/ferrandino_2020

What are your thoughts on limonene as a biomarker? Could administered probes be a useful way forward in breath research, allowing us to develop new tests supported by biological insights? What other compounds on breath could be useful in the early detection of liver disease?