Vibrational behavior of Gelucire 50/13 by Raman and IR spectroscopies: A focus on the 1800-1000 cm-1 spectral range according to temperature and degree of hydration

The present paper reports on physical and thermal properties of polyoxyethylene glycol glycerides (Gelucire 50/13) used as sustained release matrix forming agent in pharmaceutical applications. Gelucire 50/13 was essentially studied by Raman and IR spectroscopies according to the temperature and the degree of hydration. The hydration behavior of this amphiphilic excipient has been investigated with increasing water contents to study the behavior during dissolution. In the spectral range 1800-1000 cm(-1), Raman and IR spectroscopies of Gelucire 50/13 were performed to characterize the contribution of its each components at room temperature, with emphasis placed on the evolution of the CH2 wagging and twisting, nu(C C) and nu(C-O) vibrational modes regions (1400-1000 cm(-1)), along with analysis of the IR and Raman-active delta(CH2) deformation region (1500-1400 cm(-1)). In comparison with temperature and degree of hydration, in the spectral range 1800-1000 cm(-1), the vibrational changes were directly correlated with conformational changes of the Gelucire structure. Overall, IR and Raman spectroscopy clearly demonstrated that the different functional groups studied could be characterized independently, allowing for the understanding of their role in Gelucire structure. (C) 2014 Elsevier B.V. All rights reserved.