Dermatologists recommend sunscreen as a protective measure against excessive amounts of sunlight in order to prevent UV induced erythema (sunburn). Manufacturers have developed sunscreens that protect from most of the harmful solar UVA and UVB radiation and are differentiated by “sun protection factors” (SPFs). Ideally, the larger the SPF value of a sunscreen is, the longer an individual using the sunscreen can stay out in the sun without damage. Commercial sunscreens contain various compounds that absorb or physically block UV radiation, both of which are properties that can be exploited when determining the concentrations of these compounds. Here, undergraduate students were able to evaluate and compare the concentration of zinc in different sunscreens using inductively coupled plasma spectroscopy (ICP). Furthermore, sunscreen lotions containing organic UV absorbers were analyzed using high performance liquid chromatography (HPLC) to investigate the concentration of the organic UV absorber, such as avobenzone, oxybenzone, and octocrylene. The values obtained by ICP and HPLC were compared to those reported by the sunscreens’ manufacturers. Scanning electron microscopy with energy dispersive spectroscopy was used to detect agglomeration, which is an issue is of special concern in sunscreens with high SPF values. By incorporating these interesting characterization techniques, students are able to combine both spectroscopy and chromatography methods to analyze inorganic and organic components of sunscreens but these experiments could also be adapted to other commercial cosmetic formulations.<br/>

Analysis of metal oxide and organic UV absorbers in commercial sunscreens

253rd National Meeting (2017)

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