Photodegradation of common environmental pharmaceuticals and estrogens in river water

Photodegradation rates of five pharmaceuticals (gemfibrozil, ibuprofen, ketoprofen, naproxen, and propranolol) and of four estrogens (estriol, estrone [E-1] 17 beta-estradiol [E-2], and 17 alpha-ethinylestradiol [EE2] which are common contaminants in the aquatic environment, were measured in both purified and river water at environmentally relevant concentrations (1-2 mu g/L) and different oxygen concentrations. Solutions were irradiated with a xenon arc lamp (765 W/m(2); 290 nm < lambda < 700 nm) and analyzed using a high-performance liquid chromatography-tandem mass spectrometry method with electrospray ionization for pharmaceuticals and atmospheric pressure photoionization for estrogens. In river water, half-lives were 4. 1 h for ketoprofen, 1. 1 min for propranolol, 1.4 h for naproxen, 2 to 3 h for estrogens, and 15 It for gemfibrozil and ibuprofen. In air-saturated purified water, rates generally were slower except for that of ketoprofen, which reacted with a half-life of 2.5 min. Naproxen, propranolol, and E, reacted with half-lives of 1.9, 4.4, and 4.7 h, respectively. The EE2, estriol, E-2, gemfibrozil, and ibuprofen reacted with half-lives of 28.4, 38.2, 41.7, 91.4, and 205 h, respectively. The presence of oxygen doubled the direct photolysis rates of naproxen and propranolol. In nonautoclaved river water, 80% of E-2 rapidly biotransformed to E-1 within less than 20 min, whereas all other compounds remained stable over 22 h.