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Characterization of cosmetic dispersion by centrifugal analyser
Tumová, Šárka ; Bokrová, Jitka (referee) ; Doskočil, Leoš (advisor)
Cosmetic products are widely used nowadays. These products are mostly emulsion systems, in which processes that lower physical stability can take place. This can leads among others to the shortening of the expiration date or to the reduction of the efficacy of the product. So, in the cosmetic practice, the physical stability is monitoring by tests. There are more types of these tests and they can be realized under different conditions. This Bachelor Thesis is focused on monitoring the physical stability of samples of cosmetics products by using an analytical centrifuge LUMiSizer and by using methods that are commonly used in a cosmetic practice and development. The aim of this study is to compare single results and to verify the suitability of the use of LUMiSizer for accelerated determine of the physical stability of cosmetic products. The stability of samples over time and the effect of the temperature on the stability of samples were monitoring by using the LUMiSizer device. Freeze-Thaw cycles and the conventional method of testing the stability of samples were applied as well. There was also determined the effectiveness of the stability test, mentioned by the literature, in this work. Based upon the results of experiments that were carried out and upon information given by manufacturers of samples that were used, the LUMiSizer device was evaluated as a useful tool for assessing the stability of samples although results obtained by the LUMiSizer device are not exactly the same as results of the conventional method. Although the application of additional methods is recommended.
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The long-term stability and properties of a skin cream with addition of liposomes
Müllerová, Kristýna ; Pekař, Miloslav (referee) ; Enev, Vojtěch (advisor)
The aim of the thesis was to design a formulation and subsequently prepare a native skin cream and skin creams enriched with liposomal particles with encapsulated vitamin E. After preparation of the skin creams, their stability and rheological properties were studied at given time intervals during storage for 12 weeks. The stability of the prepared samples was determined using a LUMiSizer analytical centrifuge with STEP-Technology. Among the rheological properties, changes in the rate of structure recovery of the formulations were monitored, as well as changes in zero and infinite viscosity, which can be presented as changes in viscosity during product storage and changes in viscosity during application and spreading on the skin. All stability and rheological tests were performed for a temperature of 25 °C, which also corresponded to the storage temperature, and for a temperature of 37 °C, which approximately corresponds to the human body temperature. According to the results, the sample without the addition of liposomes showed the highest stability and the skin cream with the addition of 10 wt.% liposomes at 1 week of age showed the best spreadability. Next, the characterization of liposomal particles was performed. Finally, a sensory analysis was performed where the evaluators compared the fresh native skin cream, the native skin cream at 12 weeks of age, the fresh skin cream with the highest liposome content and the skin cream with the highest liposomal particle content at 12 weeks of age.
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Characterization of cosmetic dispersion by centrifugal analyser
Tumová, Šárka ; Bokrová, Jitka (referee) ; Doskočil, Leoš (advisor)
Cosmetic products are widely used nowadays. These products are mostly emulsion systems, in which processes that lower physical stability can take place. This can leads among others to the shortening of the expiration date or to the reduction of the efficacy of the product. So, in the cosmetic practice, the physical stability is monitoring by tests. There are more types of these tests and they can be realized under different conditions. This Bachelor Thesis is focused on monitoring the physical stability of samples of cosmetics products by using an analytical centrifuge LUMiSizer and by using methods that are commonly used in a cosmetic practice and development. The aim of this study is to compare single results and to verify the suitability of the use of LUMiSizer for accelerated determine of the physical stability of cosmetic products. The stability of samples over time and the effect of the temperature on the stability of samples were monitoring by using the LUMiSizer device. Freeze-Thaw cycles and the conventional method of testing the stability of samples were applied as well. There was also determined the effectiveness of the stability test, mentioned by the literature, in this work. Based upon the results of experiments that were carried out and upon information given by manufacturers of samples that were used, the LUMiSizer device was evaluated as a useful tool for assessing the stability of samples although results obtained by the LUMiSizer device are not exactly the same as results of the conventional method. Although the application of additional methods is recommended.
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