title: Photodegradation of antibiotics under simulated solar radiation: implications for their environmental fate.
abstract: Roxithromycin, erythromycin, ciprofloxacin and sulfamethoxazole are frequently detected antibiotics in environmental waters. Direct and indirect photolysis of these problematic antibiotics were investigated in pure and natural waters (fresh and salt water) under irradiation of different light sources. Fundamental photolysis parameters such as molar absorption coefficient, quantum yield and first order rate constants are reported and discussed. The antibiotics are degraded fastest under ultraviolet 254 nm, followed by 350 nm and simulated solar radiation. The composition of the matrix (pH, dissolved organic content, chloride ion concentration) played a significant role in the observed photodegradation. Under simulated solar radiation, ciprofloxacin and sulfamethoxazole degrade relatively quickly with half-lives of 0.5 and 1.5h, respectively. However, roxithromycin and erythromycin, macrolides are persistent (half-life: 2.4-10 days) under solar simulation. The transformation products (15) of the targeted antibiotics produced under irradiation experiments were identified using high resolution mass spectrometry and degradation pathways were proposed.
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA. Electronic address: sbatc001@fiu.edu.
authors.forename: Sudha Rani
authors.initials: SR
authors.lastname: Batchu
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA. Electronic address: vpand001@fiu.edu.
authors.forename: Venkata R
authors.initials: VR
authors.lastname: Panditi
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA. Electronic address: osheak@fiu.edu.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Shea
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA. Electronic address: gardinal@fiu.edu.
authors.forename: Piero R
authors.initials: PR
authors.lastname: Gardinali
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects*; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects*; D008956:Models, Chemical; D010782:Photolysis; D013472:Sunlight
chemical_list: D000900:Anti-Bacterial Agents; D004785:Environmental Pollutants
keywords: Antibiotics; High resolution mass spectrometry; Intermediates; Photodegradation; Photolysis products; Simulated solar radiation