Persistence of Ibuprofen, Ketoprofen, Diclofenac and Clofibric Acid in Natural Waters

The presence and persistence of drugs in natural waters is an issue of high environmental interest, because of the biological activity of these emergent contaminants. In this work a gas chromatography-mass spectrometry analytical method was applied to a persistence study of ibuprofen, ketoprofen, diclofenac and clofibric acid in raw and lake water samples stored at room temperature under sunlight and dark conditions. Pharmaceuticals degradation follow a pseudo first order kinetic and their half-lives calculated in every experimental condition. The most rapid degradation rate was observed in non-filtered open recipients samples exposed to sunlight, where environmental factors such as adsorption on particulates, biodegradation and sunlight were present. Under sunlight, ketoprofen was quickly degraded with half-lives from 7.1 to 11.9 hours, while clofibric acid had the higher persistence (t1/2 = 130.7 – 495.1 days).