Use of a TG/DTA/Raman system enabled real time collection of Raman spectra during the dehydration of Risedronate, the active pharmaceutical ingredient in the osteoporosis drug Actonel. Raman spectra collected during the dehydration of this material show a crystal lattice adjustment below the boiling point of water facilitating interpretation of the TG/DTA thermal profile. Raman spectra also revealed recrystallization processes subsequent to loss of lattice water that were not evident in the thermal analysis profile. Spectral evidence showing the formation and disappearance of a second hydrate form are observed during the dehydration of this material. In addition, spectral evidence indicating the presence of an anhydrate form of this material are observed prior to thermal induced degradation of this material.

Modification of a commercially available TG/DTA instrument enabled development of a working TG/DTA/Raman system. The TG/DTA was modified by replacing a portion of the furnace wall above the sample and reference holders with a double layer insulated quartz window. The quartz window provided ready access for Raman spectroscopy, enabling simultaneous collection of TGA, DTA, and Raman data during thermal analytical experiments. Insertion of the quartz glass window did not impact TGA or DTA performance as demonstrated by the comparison of baseline drift and temperature calibration for modified and unmodified furnaces.