title: Variable heating rate thermogravimetric analysis as a mechanism to improve efficiency and resolution of the weight loss profiles of three model pharmaceuticals.
abstract: The effect of variable heating rates on the efficiency or resolution of the derivative of the thermogravimetry profiles of three model pharmaceutical compounds was investigated. The variable heating system utilized computer controlled algorithms for the evaluation of crystalline sodium warfarin, DuP 532 and hydrated DuP 925 as model compounds with one, two and three step weight loss profiles, respectively. As the heating modes were increased through each of the eight settings, the minimum heating rate decreased while the efficiency and resolution and the analysis times increased. The observed weight loss remained relatively constant for each of the model compounds as the heating modes were increased. The efficiency of the derivative of the weight loss profile of crystalline sodium warfarin increased from 121 to 621 as the heating mode increased. The resolution between the two steps of the derivative of the weight loss profile of DuP 532 increased from 1.73 to 3.88 as the heating mode increased. For hydrated DuP 925, the resolution increased from 1.49 to 5.46 between steps 1 and 2 of the derivative of the weight loss profile and from 1.87 to 3.24 between steps 2 and 3 of the derivative of the weight loss profile. Variable heating rates provided a valuable aid in obtaining high efficiency/resolution thermograms. The enhanced efficiency/resolution permitted greater separation of the volatilization process, especially for samples with multi-step weight loss profiles. Increasing the heating mode afforded higher efficiencies/resolutions that typically reached a maximum value at mode 6.
authors.affiliation: Pharmacy Research and Development, DuPont Pharmaceuticals Company, Wilmington, DE 19880-0400, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Maurin
authors.forename: A
authors.initials: A
authors.lastname: Taylor
mesh_terms: D000465:Algorithms; D000925:Anticoagulants / Q000032:analysis*; D000998:Antiviral Agents / Q000032:analysis*; D003201:Computers; D006358:Hot Temperature; D007093:Imidazoles / Q000032:analysis*; D008956:Models, Chemical; D013777:Tetrazoles / Q000032:analysis*; D013818:Thermogravimetry / Q000379:methods*; D017973:Tungsten Compounds / Q000032:analysis*; D014638:Vanadates / Q000032:analysis*; D014859:Warfarin / Q000032:analysis*; D005466:Fluorocarbons
chemical_list: D000925:Anticoagulants; D000998:Antiviral Agents; D007093:Imidazoles; D013777:Tetrazoles; D017973:Tungsten Compounds; D014638:Vanadates; D014859:Warfarin; C069045:DuP 532; D005466:Fluorocarbons; C076004:DuP 925