Far-infrared spectroscopy, X-ray diffraction, and thermogravimetric different thermal analyses on crude and processed Pyritum / 中草药

ABSTRACT

Objective: To establish a method by which the multi-analysis and identification on the crude and processed Pyritum (natural coppor) could be carried out. Methods: The qualitative and semi-quantitative analyses of the structure, chemical composition, and thermal stability of crude and processed Pyritum were determined by means of far-infrared (FIR) spectroscopy, X-ray diffraction (XRD) analyses, and thermogravimetric differential thermal analysis (TG-DTA). Results: FIR spectroscopy showed that processed Pyritum had the chemical composition of Fe2O3. XRD analysis indicated that in crude Pyritum, the phase was mainly made up of FeS2; however, in processed one, the more complicated phase was made up of Fe7S 8, FeO(OH), Fe2O3, and Fe3O 4, etc and appeared. Thermal analysis suggested that the phase FeS2 can be gradually decomposed, the composition structure of the processed Pyritum changed less than that of the crude one when heated from 400 to 1 000°C. Conclusion: The method of analyzing and identifying the crude and processed Pyritum is feasible.