For DBC no method for the assessment of the degree of butyrylation—based on FT-IR measurements—is found in the literature. Several measurement peaks and reference peaks were investigated but the results were not conclusive enough to differentiate between the two studied DBC types. Comparing with a direct technique such as 13C NMR would yield a series of calibration curves, thus resulting in relevant FT-IR measurement and reference peaks. This might be the subject of further study