TY - JOUR
T1 - A Study of Moisture Sorption and Dielectric Processes of Starch and Sodium Starch Glycolate
T2 - Theme: Formulation and Manufacturing of Solid Dosage Forms Guest Editors: Tony Zhou and Tonglei Li
AU - Hiew, Tze Ning
AU - Huang, Rongying
AU - Popov, Ivan
AU - Feldman, Yuri
AU - Heng, Paul Wan Sia
N1 - Publisher Copyright:
© 2017, Springer Science+Business Media, LLC.
PY - 2017/12/1
Y1 - 2017/12/1
N2 - Purpose: This study explored the potential of combining the use of moisture sorption isotherms and dielectric relaxation profiles of starch and sodium starch glycolate (SSG) to probe the location of moisture in dried and hydrated samples. Methods: Starch and SSG samples, dried and hydrated, were prepared. For hydrated samples, their moisture contents were determined. The samples were probed by dielectric spectroscopy using a frequency band of 0.1 Hz to 1 MHz to investigate their moisture-related relaxation profiles. The moisture sorption and desorption isotherms of starch and SSG were generated using a vapor sorption analyzer, and modeled using the Guggenheim-Anderson-de Boer equation. Results: A clear high frequency relaxation process was detected in both dried and hydrated starches, while for dried starch, an additional slower low frequency process was also detected. The high frequency relaxation processes in hydrated and dried starches were assigned to the coupled starch-hydrated water relaxation. The low frequency relaxation in dried starch was attributed to the local chain motions of the starch backbone. No relaxation process associated with water was detected in both hydrated and dried SSG within the frequency and temperature range used in this study. The moisture sorption isotherms of SSG suggest the presence of high energy free water, which could have masked the relaxation process of the bound water during dielectric measurements. Conclusion: The combined study of moisture sorption isotherms and dielectric spectroscopy was shown to be beneficial and complementary in probing the effects of moisture on the relaxation processes of starch and SSG.
AB - Purpose: This study explored the potential of combining the use of moisture sorption isotherms and dielectric relaxation profiles of starch and sodium starch glycolate (SSG) to probe the location of moisture in dried and hydrated samples. Methods: Starch and SSG samples, dried and hydrated, were prepared. For hydrated samples, their moisture contents were determined. The samples were probed by dielectric spectroscopy using a frequency band of 0.1 Hz to 1 MHz to investigate their moisture-related relaxation profiles. The moisture sorption and desorption isotherms of starch and SSG were generated using a vapor sorption analyzer, and modeled using the Guggenheim-Anderson-de Boer equation. Results: A clear high frequency relaxation process was detected in both dried and hydrated starches, while for dried starch, an additional slower low frequency process was also detected. The high frequency relaxation processes in hydrated and dried starches were assigned to the coupled starch-hydrated water relaxation. The low frequency relaxation in dried starch was attributed to the local chain motions of the starch backbone. No relaxation process associated with water was detected in both hydrated and dried SSG within the frequency and temperature range used in this study. The moisture sorption isotherms of SSG suggest the presence of high energy free water, which could have masked the relaxation process of the bound water during dielectric measurements. Conclusion: The combined study of moisture sorption isotherms and dielectric spectroscopy was shown to be beneficial and complementary in probing the effects of moisture on the relaxation processes of starch and SSG.
KW - dielectric relaxation
KW - dielectric spectroscopy
KW - moisture sorption isotherm
KW - sodium starch glycolate
KW - starch
UR - http://www.scopus.com/inward/record.url?scp=85028979929&partnerID=8YFLogxK
U2 - 10.1007/s11095-017-2252-x
DO - 10.1007/s11095-017-2252-x
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C2 - 28875274
AN - SCOPUS:85028979929
SN - 0724-8741
VL - 34
SP - 2675
EP - 2688
JO - Pharmaceutical Research
JF - Pharmaceutical Research
IS - 12
ER -