title: Sample preservation for the analysis of antibiotics in water.
abstract: This paper describes a stability study performed for 56 antibiotics belonging to 9 different groups--macrolides, tetracyclines, fluoroquinolones, quinolones, penicillins, cephalosporines, lincosamides, sulfonamides and nitroimidazole antibiotics--in purified water samples fortified with the selected compounds at 10 ng/ml. For this purpose, three different sample preservation modes were tested with the aim of avoiding biotic and abiotic degradation: (i) storage at -20°C, (ii) storage at -20°C with 0.1% of EDTA and (iii) pre-concentration in a solid phase extraction cartridge (SPE), which was afterwards stored at -20°C. Concentrations of antibiotics in the samples preserved using the different protocols were monitored after 0, 1, 2 and 12 weeks. The results showed that, for the accurate determination of all compounds they should be analyzed right after sampling. However, if this is not possible, most of the antibiotics can be analyzed within the 1st week after sampling and preservation at -20°C (with or without EDTA) or in a SPE cartridges at -20°C. Nonetheless, some antibiotics found extensively in the environment, such as sulfamethoxazole, ciprofloxacin, ofloxacin, erythromycin, azithromycin and clarithromycin exhibited low stability after 1 week preservation and, therefore, they should be analyzed within this time.
authors.affiliation: Catalan Institute for Water Research (ICRA), H(2)O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003 Girona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Llorca
authors.affiliation: Catalan Institute for Water Research (ICRA), H(2)O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003 Girona, Spain.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Gros
authors.affiliation: Catalan Institute for Water Research (ICRA), H(2)O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003 Girona, Spain. Electronic address: srodriguez@icra.cat.
authors.forename: Sara
authors.initials: S
authors.lastname: Rodríguez-Mozaz
authors.affiliation: Catalan Institute for Water Research (ICRA), H(2)O Building, Scientific and Technological Park of the University of Girona, Emili Grahit 101, 17003 Girona, Spain; Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: Damià
authors.initials: D
authors.lastname: Barceló
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004355:Drug Stability; D052616:Solid Phase Extraction / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods; D014867:Water / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D014867:Water
keywords: Antibiotics; Liquid chromatography coupled to mass spectrometry in tandem; Preservation stability in water