Here Comes the Sun - Using Laser Diffraction to Characterize Cosmetics
Nano- and microparticles are used in the cosmetics industry to enhance product performance and meet the high expectations of consumers. Particle size affects different properties such as skin feel, texture, color or UV absorbance. Moreover, the European Commission has issued a regulation to guarantee the safety of cosmetic products, making it necessary to characterize raw materials for cosmetic industry and final products. Here we demonstrate that the PSA is a wellsuited tool for characterizing different cosmetic products in terms of particle size distribution.
Nowadays it’s becoming ever more important for the cosmetics industry to create not only make-up and fragrance products, but also products containing many active components such as sunscreen or anti-aging components, able to provide multiple benefits at the same time. The cleaning effect, moisture balance, stimulation of the skin’s metabolism and protection from harmful ultraviolet radiation are some of the main purposes of the skin care cosmetics. Cosmetics for skin care contain substances, which support the homeostasis function, so that the skin is maintained in a beautiful and healthy condition (1).
The formulation of new cosmetics aims for creating not only versatile, but also safe-to-apply products. To guarantee the safety of cosmetic products and a high level of protection of human health, the European Commission has issued a regulation containing certain standards that every product on the market must meet. In fact, according to some preliminary studies, certain types of nanoparticles can be toxic to human tissue and cell cultures (2). The investigation of the particle size in cosmetics allows a qualitative characterization of raw materials and the final product. Such characterization is crucial for the development of new formulations exhibiting excellent texture and skin feel while maintaining highest functionality.
Many sunscreens and facial powders contain zinc oxide or titanium oxide particles smaller than 100 nm.
There are open discussions about the possible inhalation or skin absorption of nanoparticles through cosmetics. Therefore, manufactures consider particle size as very important to estimate the healthy risk associated to their products.
Titanium dioxide, a pigment that is used for various cosmetic products, is especially popular because of its ability to strongly absorb the UV light and protect the skin due to its particular chemical and physical properties. It is also referred to as “attenuation grade” material, reducing the intensity of received UV light when applied. However, this attenuation grade depends on the titanium oxide’s particle size, becoming less effective with increasing particle size (3).
In addition to the mentioned parameters, particle size also affects product qualities such as texture and skin feel, color and shade, smoothness and powder compaction. A major disadvantage of titanium dioxide in sunscreen is the strong whitening effect. For this reason, additives such as mica powder can be added to improve the skin’s appearance. Mica is a non-toxic mineral, ground to fine powder (mica powder). Due to its reflective properties, mica is often used as a coloring additive in cosmetics and leaves a certain pearly glow.
In the present application report a titanium dioxide powder sample, two different sun protection formulations and mica powder were characterized by the means of laser diffraction technology.
1. Mitsui, Takeo. New cosmetic science. s.l. : Elsevier, 1997.
2. Toxicity of nanoparticles and an overview of current experimental models. Bahadar, Haji, et al., et al. 1, s.l. : Pasteur Institute of Iran, 2016, Iranian biomedical journal, Bd. 20, S. 1.
3. Kobo. Literature. Kobo. [Online] [Zitat vom: 23. January 2019.] www.koboproductsinc.com/Literature.aspx.
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