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ASTM Selected Technical Papers
Techniques in Thermal Analysis: Hyphenated Techniques, Thermal Analysis of the Surface, and Fast Rate Analysis
By
Wei-Ping Pan
Wei-Ping Pan
1
Western Kentucky University
?
Bowling Green, Kentucky Symposium Co-chairman and editor
Search for other works by this author on:
Lawrence Judovits
Lawrence Judovits
2
Arkema Inc.
?
King of Prussia, Pennsylvania Symposium Co-chairman and editor
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ISBN-10:
0-8031-5616-2
ISBN:
978-0-8031-5616-6
No. of Pages:
142
Publisher:
ASTM International
Publication date:
2007

TGA-DTA plays a central role in the strategy outlined for early evaluation of the solid state forms available to pharmaceutical new chemical entities. Understanding of the solid state forms becomes more difficult when individual samples present as mixed forms, especially when it is not immediately recognized that the samples represent a mixture. In this study, TGA-DTA, in combination with light microscopy and powder X-ray diffraction, provided immediate evidence that samples represented mixed solid state forms. The initial assessment was made using as little as 5 mg of sample. Hygroscopicity challenges provided further proof for mixed forms. To make a definite assignment of the solid state forms present, isolation of pure phases of the suspected individual forms was necessary. Success of this testing strategy is illustrated using an example of mixed salt stoichiometry and mixed hydration states. A hierarchy is suggested for efficient isolation efforts when a complex mixture of solid state samples is present.

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Redman-Furey
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, and
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,
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, Ed.,
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,
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Davey
,
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and
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, “
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,”
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,
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,
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Morris
,
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, “
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,”
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, Eds., New York,
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6.
Redman-Furey
,
N. L.
and
Collins
,
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, “
Thermoanalytical Characterization of Pharmaceutical Materials: Small Molecule Applications
,”
American Pharmaceutical Review
, Vol.
5
, No.
1
,
2002
, pp. 102–107.
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