As far as the position and intensit

As far as the position and intensity of various bands of the KG and KOG were concerned, the major bands centered at 1800–1200 cm−1 showed significant change, which shifted to a little lower wave number when the KG was degraded and, at the same time, their intensity was decreased.

The peak at 1723 cm−1 disappeared in the spectra of KOG, these significant changes suggested the KG degradation occurred.