title: Aqueous chlorination of mefenamic acid: kinetics, transformation by-products and ecotoxicity assessment.
abstract: Mefenamic acid (Mfe) is one of the most frequently detected nonsteroidal anti-inflammatory drugs in the environment. This study investigated the kinetics and the transformation by-products of Mfe during aqueous chlorination. The potential ecotoxicity of the transformation by-products was also evaluated. In the kinetic study, the second-order rate constant (kapp) for the reaction between Mfe and free available chlorine (FAC) was determined at 25 ± 0.1 °C. The result indicated that the degradation of Mfe by FAC is highly pH-dependent. When the pH was increased from 6 to 8, it was found that the kapp for the reaction between Mfe and FAC was decreased from 16.44 to 4.4 M(-1) s(-1). Characterization of the transformation by-products formed during the chlorination of Mfe was carried out using liquid chromatography-quadrupole time-of-flight accurate mass spectrometry. Four major transformation by-products were identified. These transformation by-products were mainly formed through hydroxylation, chlorination and oxidation reactions. Ecotoxicity assessment revealed that transformation by-products, particularly monohydroxylated Mfe which is more toxic than Mfe, can be formed during aqueous chlorination.
authors.affiliation: Environmental Research Group, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia. khengsoo@um.edu.my.
authors.forename: Wan Nor
authors.initials: WN
authors.lastname: Adira Wan Khalit
authors.forename: Kheng Soo
authors.initials: KS
authors.lastname: Tay
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry*; D002853:Chromatography, Liquid; D054879:Halogenation; D015386:Hazardous Substances / Q000737:chemistry*; D007700:Kinetics; D008528:Mefenamic Acid / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D015386:Hazardous Substances; D014874:Water Pollutants, Chemical; D008528:Mefenamic Acid; D002713:Chlorine