Science Serving Maryland's Coasts
Michael Gonsior, Ph.D.
Chesapeake Biological Laboratory
Determining the Photochemical Fate of Organic UV-filters Commonly Found in Sunscreen in Natural Waters
Chromophoric dissolved organic matter (CDOM) holds the potential to drastically change the light field of aquatic environments. Once in solution, organic UV-filters commonly found in sunscreen such as oxybenzone, octocrylene, and octinoxate fall within the definition of CDOM, dissolved organic matter that absorbs UV and visible light. Thus, these compounds hold the potential participate in photochemical reactions, altering both the chemical makeup and light field of an aquatic environment. To date, limited information exists on the photochemical degradation of sunscreen organic UV-filters in natural waters. Thus, we used a customdesigned photodegradation system to continuously photo-irradiate samples with simulated sunlight and quantify changes in optical properties throughout long-term experiments. We utilized excitation-emission matrix spectroscopy to determine absorbance and fluorescence spectra. Additionally, sub-samples were collected during 24h irradiation experiments to determine the change in concentrations of the examined UV-filters using LC-qqq MS. Results revealed exponential decrease in concentration of the parent compound during photoirradiation, no OpenFluor database comparison matches, a variety of photo-products, and suggest the possibility of secondary photo-products.
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