Comparison of methods for fullerene detection and measurements of reactive oxygen production in cosmetic products
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Numerous commercial products incorporate novel engineered nanomaterials such as gold, silica, zinc oxide, and fullerenes in complex matrices such as polymer composites, creams, and textiles. Analytical methods for detecting nanomaterials in complex matrices are not well developed. Moreover, nanomaterial content and properties of these commercial products are typically unknown and protected for proprietary reasons. This study had two primary aims: detection of C60 within commercial face creams to establish a baseline concentration in these products (the first time this has been performed) and detection of residual C60 reactivity remaining in the products aged in water under various light conditions with a view toward environmental exposure assessment. To achieve these aims, three commercial creams advertised as containing the fullerene nanomaterials were investigated using a range of analytical techniques. Among the detection methods tested, only extraction followed by high-performance liquid chromatography was able to detect fullerenes in these products. The measured quantities of C60 in these creams represented <0.005% (w/w) with an unknown yield because total amounts added to the creams were unknown. Production of reactive oxygen species from these face creams was measured after aging them in water as well as exposing them to solar spectrum illumination or ultraviolet light, or storage in the dark. Singlet oxygen generated in the products after 48 h of aging was correlated with the amounts of C60 extracted from preaged samples, indicating residual photochemical reactivity and pointing toward the long-term impacts of utilizing these materials in commercial products. © 2010, Mary Ann Liebert, Inc.