title: Photolysis of sulfamethoxypyridazine in various aqueous media: aerobic biodegradation and identification of photoproducts by LC-UV-MS/MS.
abstract: Sulfonamides are one of the most frequently used antibiotics worldwide. Therefore, mitigation processes such as abiotic or biotic degradation are of interest. Photodegradation and biodegradation are the potentially significant removal mechanisms for pharmaceuticals in aquatic environments. The photolysis of sulfamethoxypyridazine (SMP) using a medium pressure Hg-lamp was evaluated in three different media: Millipore water pH 6.1 (MW), effluent from sewage treatment plant pH 7.6 (STP), and buffered demineralized water pH 7.4 (BDW). Identification of transformation products (TPs) was performed by LC-UV-MS/MS. The biodegradation of SMP using two tests from the OECD series was studied: Closed Bottle test (OECD 301 D), and Manometric Respirometry test (OECD 301 F). In biodegradation tests, it was found that SMP was not readily biodegradable so it may pose a risk to the environment. The results showed that SMP was removed completely within 128 min of irradiation in the three media, and the degradation rate was different for each investigated type of water. However, dissolved organic carbon (DOC) was not removed in BDW and only little DOC removal was observed in MW and STP, thus indicating the formation of TPs. Analysis by LC-UV-MS/MS revealed new TPs formed. The hydroxylation of SMP represents the main photodegradation pathway.
authors.affiliation: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg, Germany. drndahshan@yahoo.com
authors.forename: Nareman D H
authors.initials: ND
authors.lastname: Khaleel
authors.forename: Waleed M M
authors.initials: WM
authors.lastname: Mahmoud
authors.forename: Ghada M
authors.initials: GM
authors.lastname: Hadad
authors.forename: Randa A
authors.initials: RA
authors.lastname: Abdel-Salam
authors.forename: Klaus
authors.initials: K
authors.lastname: Kümmerer
mesh_terms: D000332:Aerobiosis; D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000528:radiation effects*; D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D010100:Oxygen / Q000378:metabolism; D010782:Photolysis; D012722:Sewage / Q000382:microbiology; D013421:Sulfamethoxypyridazine / Q000378:metabolism* / Q000528:radiation effects*; D053719:Tandem Mass Spectrometry / Q000379:methods; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D000900:Anti-Bacterial Agents; D012722:Sewage; D014874:Water Pollutants, Chemical; D010100:Oxygen; D013421:Sulfamethoxypyridazine