Antonijevic, Milan D. ORCID: 0000-0002-5847-7886 , Craig, Duncan Q. M. and Barker, Susan A. (2008) The role of space charge formation in the generation of thermally stimulated current (TSC) spectroscopy data for a model amorphous drug system. International Journal of Pharmaceutics, 353 (1-2). pp. 8-14. ISSN 0378-5173 (doi:https://doi.org/10.1016/j.ijpharm.2007.11.004)

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Abstract

Thermally stimulated current (TSC) spectroscopy is attracting increasing attention as a means of materials characterization, particularly in terms of measuring slow relaxation processes in solid samples. However, wider use of the technique within the pharmaceutical field has been inhibited by difficulties associated with the interpretation of TSC data, particularly in terms of deconvoluting dipolar relaxation processes from charge distribution phenomena. Here, we present evidence that space charge and electrode contact effects may play a significant role in the generation of peaks that have thus far proved difficult to interpret. We also introduce the use of a stabilization temperature in order to control the space charge magnitude. We have studied amorphous indometacin as a model drug compound and have varied the measurement parameters (stabilization and polarization temperatures), interpreting the changes in spectral composition in terms of charge redistribution processes. More specifically, we suggested that charge drift and diffusion processes, charge injection from the electrodes and high activation energy charge redistribution processes may all contribute to the appearance of shoulders and 'spurious' peaks. We present recommendations for eliminating or reducing these effects that may allow more confident interpretation of TSC data.

Item Type:	Article
Additional Information:	[1] Available online: 20 February 2008. [2] Published in print: 2 April 2008. [3] Published in International Journal of Pharmaceutics, 2 April 2008, Volume 353, Issues 1–2, pp. 8–14.
Uncontrolled Keywords:	amorphous, depletion region, dielectric, pharmaceutical, thermally stimulated current, space charge
Subjects:	T Technology > TP Chemical technology R Medicine > RS Pharmacy and materia medica
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science > School of Science (SCI)
Related URLs:	Publisher Organisation
Last Modified:	11 Feb 2020 13:13
URI:	http://gala.gre.ac.uk/id/eprint/2181

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