FT-IR spectroscopy applied for identification of a mineral drug substance in drug products: Application to bentonite

Abstract

The aim of this study is to prove the effectiveness of IR spectroscopy as an identification test able to discriminate between mineral compounds in mixtures. This work is concerned with the physical characterisation of purified bentonite, bentonite in organic mixtures and organic excipients, and mineralized organic mixture containing bentonite using FT-IR spectroscopy. The different spectra were compared with each other in order to determine fingerprints of bentonite represented by bands located at 3632 cm-1 and 3437 cm-1. The analysis of the spectra of the nonmineralized mixture demonstrates the presence of two bands at 1454 and 2928 cm-1, superimposed on those of the excipients and which disappear after 2 hours of mineralization at 500°C. Finally, we notice a displacement of the stretching band of H2O to the right with increasing the proportion of the excipients.