Comment on “Ozonation of triterpenoids: Implications for early diagenesis of biomarkers in oxic environments” by Tay et al. (2013)

The article entitled “Ozonation of triterpenoids: Implications for early diagenesis of biomarkers in oxic environments” (Tay, K.S., Rahman, N.A., Abas, M.R.B, Simoneit, B.R.T., 2013. Organic Geochemistry 57, 34-40) deals with an investigation of the early diagenetic transformations undergone by higher plant triterpenoids under oxic conditions by means of laboratory experiments involving various triterpenes in the presence of ozone. Several aspects of the publication by Tay et al. (2013) are questionable, and are discussed in detail here. These comprise (i) the analytical procedure (based mainly on gas chromatography-mass spectrometry, GC-MS) used for the investigation of reaction mixtures likely to contain thermally labile (poly)oxygenated triterpenoids, (ii) the proposed mechanisms involving the hydroxyl radical as the key oxidizing species, (iii) the interpretation of mass spectra of the products and the structural assignments therefrom, and (iv) the geochemical relevance of the experiments with respect to non-biological oxidative alteration undergone by higher plant triterpenes in sediments.