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Fulvic Acid Mediated Photolysis of Ibuprofen in Water.
Citation:
Jacobs, L. E., R. L. Fimmen, Y. Chin, H. E. Mash, AND L. K. Weavers. Fulvic Acid Mediated Photolysis of Ibuprofen in Water. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 45(15):4449-4458, (2011).
Impact/Purpose:
To inform the public.
Description:
Photolysis of the nonsteroidal anti-inflammatory drug ibuprofen was studied in solutions of fulvic acid (FA) isolated from Pony Lake, Antarctica; Suwannee River, GA, USA; and Old Woman Creek, OH, USA. At an initial concentration of 10 µM ibuprofen degrades by direct photolysis, but the presence of fulvic acids (6 mg C/L) significantly increases reaction rates (×5). These reactions proceeded even more quickly in FA solutions at lower ibuprofen concentrations (0.1 µM). Incomplete quenching of the reaction in the presence of isopropanol suggests that the hydroxyl radical is only partially responsible for ibuprofen’s photodegradation in FA solutions, and other reactive transients likely play an important role. Liquid chromatography quadrupole time-of-flight mass spectrometry and 1H NMR spectroscopy reveal the formation of multiple hydrophobic photoproducts, with the dominant byproduct identified as 1-(4-isobutylphenyl)ethanol as well as a minor derivative isobutylacetophenone. Pony Lake FA significantly increases the production of the major byproduct relative to yields produced by direct photolysis and the other two FA. Thus, the photolytic fate of ibuprofen in sunlit waters is affected by its initial concentration and the type of dissolved organic matter present.
