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Optical coherence tomography (OCT), rheology, thermal analysis and particle size determination applied for the characterization of cosmetic use emulsified systems

Grant number: 09/12502-5
Support type:Scholarships in Brazil - Master
Effective date (Start): March 01, 2010
Effective date (End): February 29, 2012
Field of knowledge:Health Sciences - Pharmacy - Medicines Analysis and Control
Principal researcher:André Rolim Baby
Grantee:Paula Souza Prestes
Home Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade de São Paulo (USP). São Paulo , SP, Brazil


The physical, physicochemical and chemical attributes of the emulsified systems are influenced by the characteristics of their internal phase droplets, such as: concentration, size and morphology. Thus, the aims involved the physical and physicochemical characterization of emulsions obtained from the stearyl alcohol condensed with 21 mols ethylene oxide (EO) (steareth-21) and oleyl alcohol with 20 mols EO (oleth-20), as well as, the introduction of the optical coherence tomography (OCT) as the analytical technique tool to the determination of the particle size and morphological characterization of the emulsified systems. Three formulations were prepared, differing at the surfactant used, being the emulsified system SE-1 composed by 8.0% (p/p) of oleth-20, the SE-2 by 4.0% (p/p) of oleth-20 and 4.0% (p/p) steareth-21; and the SE-3 by 8.0% (p/p) steareth-21. The preliminary stability was evaluated, such as the ph value and the rheological and thermogravimetric profiles. The presence of the crystalline gel phase was determined from microscopy with polarized light and the droplet size through regular optical microscopy, laser diffraction and OCT. The samples did not present signs of instability throughout the centrifugation and thermal stress tests. The ph value was considered compatible to human skin (4.6 to 5.8). Systems represent the non-Newtonian pseudoplastic rheological behaviour. The SE-1 presented inferior apparent viscosity (223.53 mPa.s) and the hysteresis area (2238.38 Pa/s) statistically equal to SE-2 (2911.19 Pa/s); the SE-2 presented an average value of apparent viscosity (332.20 mPa.s) and, the SE-3, superior values to both parameters (636.40 mPa.s and 4248.97 Pa/s). The oscillating tests verified the elastic character predomination to the three systems. Throughout the thermogravimetry, the profile of the three samples was similar, independent from the kind and concentration of the non-ionic surfactant. The presence of the crystalline gel phase was identified at the three systems, being apparently more pronounced to the SE-2. Either at the microscopic analysis as well as at the laser diffraction were obtained an average size of the particles minor than 6.0 µm. According to OCT results, the particles below 6.0 µm were not possible to be identified and the major particles were suggested be the internal phase of the systems, however new studies should be performed.

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Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
PRESTES, Paula Souza. Optical coherence tomography (OCT), rheology, thermal analysis and particle size determination applied for the characterization of cosmetic use emulsified systems. 2012. Master's Dissertation - Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) São Paulo.

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