Study of Homosalate Stability in Chlorinated Water and Identification Chalogenated By-Products by Gas Chromatography-Mass Spectrometry

The increasing use of sun-creams containing organic UV-filters has led to increased concentration of these compounds in aquatic environment. Chlorinated water can convert these chemicals into chlorinated products whose toxic effects are of primary concern. The new compound may be more toxic than the starting primary compound. Many studies have shown that UV filters absorb UV light and decompose under solar irradiation, due to their unstable properties. This may lead to formation of certain by-products with harmful effects. Their decomposition products can cause allergic and toxic reactions to the human skin. This study follows the stability of most commonly used UV filters, homosalate, in conditions that include those existent in swimming pools. Stability of the homosalate in chlorinated water was studied in simulated swimming pool water samples. UV spectroscopy was used to follow the reaction of homosalate in presence of free chlorine. Water samples were filtered, acidified, and extracted by use of solid-phase extraction. Gas chromatography with mass spectrometry was used to identify the major transformation by-products. Under the experimental conditions, homosalate reacted with chlorine following zero order reaction. The chemical transformation of the homosalate in chlorinated water led to formation of chlorinated by-products that was identified as: monochloro-homosalate, dichloro-homosalate and two diastereoisomers monochloro-homosalate