MWSCC Reveals the Faces of Cosmetic Science

By: Katie Anderson (Schaefer), Cosmetics & Toiletries magazine

Posted: November 10, 2011

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Jill Costa, PhD, chief perfumer at Bell Flavours & Fragrances, followed Akridge with a talk on choosing a successful fragrance for a personal care product. She explained that the vast majority of fragrance materials are hydrophobic and between log K_ow 2.5-3.5. There are a few exceptions, specifically vanilla, which has a log K_ow 0 (hydrophilic) and citrus terpenes, which have a log K_ow 5 (hydrophobic). She explained that “like dissolves like” when it comes to fragrance. Therefore, most fragrances in emulsions are incorporated into the oil phase. Fragrances equilibrate in micelle in micelle structures and into silicone or oils in solutions. However, fragrance can change based on product matrix. “The same fragrance will change in different types of matrixes such as lotion, shower gel and silicone,” added Costa. This is due to different concentrations, solubility differences and addition of other materials (water, heat). For example, shower gel is difficult to fragrance because it diluted so much in water and little is left on the skin. “You may ask, why are shower gels usually citrus and fruity, and the answer is because it works.”

Costa noted that the fragrance carrier is currently a hot topic, with popular options being dipropylene glycol for water-based formulations with high surfactants, isopropyl myristate for bath oils and hydrophobic matrices and polysorbate 20 for water-based products with low surfactants. She discussed the request by formulators to dilute a fragrance to decrease its cost. She noted that this really does not save the company a great deal of money, as more of the diluted fragrance is needed than the concentrated fragrance to have a successful scent and the diluent is an added cost. She noted that many formulators ask for water-soluble fragrance, which involves adding a surfactant such as polysorbate at 70%. She explained, “If you can solubilize the fragrance yourself, you can save your company that cost.” Costa has had a number of formulators ask her for all natural fragrances or essential oil blends. She finds that natural materials are limited and vary greatly is cost. With the request for an all-natural, allergen-free fragrance, she added “It usually doesn’t work, and if it does, it doesn’t smell nice.” She noted that essential oils can discolor a product, which can be adjusted with chelators.

After the morning presentations finished and lunch and mingling concluded, it was time for the MWSCC to name the Best Poster Award, which was sponsored by TH Hilson. Lori Hilson from the company named the award winners, which were chosen by a panel of experts selected by the MWSCC. Third place was awarded to Tao Bai from the University of Illinois in Chicago for her paper, “Roles of the Pharmacist in the Natural, Organic Cosmetic Industry,” which was co-authored by Ronald L. Koch. Second place went to Kathleen Davis from the University of Southern Mississippi, for her paper, “Acrylate/C_10-30 Alkyl Acrylate as an Osmotic Sponge, which was co-authored by Laura Anderson and Robert Y. Lochhead, PhD. Finally, the Best Poster Award was given to Andrew D. Kosal from the University of Notre Dame for his paper, “Polyelectolytes of the Poloxamer/Propylene glycol/Water system,” which was co-authored by Erin E. Wilson and Brandon L. Ashfeld. In addition to receiving their awards, the students were also given cash prizes to aid them in their pursuits of science.

The afternoon began with Kathleen Martin, a spectroscopist and research associate for McCrone Associates. Martin’s presentation was focused on identifying the materials that should not be present in a formulation. She began with the different types of contaminants that can be found in cosmetic products including: chemical contaminants such as heavy metals, dioxanes, phthalates and nitrosamines; microbiological contaminants such as bacteria and mold; and particulates such as visible and subvisible (≤50 μm). Martin’s search for contaminants typically begins from quality control personnel, the manufacturer in product development or stability testing or from consumer complaints from visual, tactile or olfactory clues. She noted that particulates can arise from the manufacturing process due to poor dispersion of ingredients, manufacturing debris, corrosion or environmental contamination. Other sources can be reaction between ingredients, raw materials, packaging and postconsumer use. Some environmental particulates can be hair, charred material, dirt, paint chips or cardboard.

To identify the particulates, Martin first uses a stereomicroscope to identify visual and tactile clues before using particulate isolation and instrumental analysis. Particle manipulation, solvent washing and filtration can all be used to isolate particulates. Instrumental analysis can involve SEM/EDS for morphology and elemental data, infrared spectroscopy and Raman spectroscopy for molecular identification, Polarized light microscopy for fibers, glass and insects and Gas chromatography/mass spectrometry for odors. Martin took attendees through her process to identify a few contaminants found in personal care products. She concluded that contaminants will always be present in products; therefore, the best a manufacturer can do is to take all the precautions they can to avoid them.