Publication details
PRESSURIZED LIQUID EXTRACTION (PLE) AND DETERMINATION OF ANTIBIOTICS (TETRACYCLINES AND SULFONAMIDES) IN BIOSOLIDS BY LC-MS/MS
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| Year of publication | 2012 |
| Type | Conference |
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| Description | Tetracyclines (TCs) and sulfonamides (SAs) are widely used antibiotics in human and veterinary medicine practice and as a result of there are not completely metabolized, they were detected in wastewaters. Several studies have also shown that antibiotics are not eliminated during waste water treatment and sewage treatment plants (STPs) are referred to be the major source of their release into environment [1]. Due to their physical and chemical properties, TCs and SAs are distributed in STPs between sludge and water phases and they are accumulated in bio-solids. The determination of antibiotics in sewage sludge it is important both in the evaluation of the efficiency of the wastewater treatment and for determining the potential reuse of bio-solids as a manure. Recently several analytical methods were developed for the determination of various antibiotics in environmental matrices by using liquid chromatography- mass spectrometry [2, 3]. In sewage sludges, pharmaceuticals are present in very low concentrations and coexist with a large number of potentially interfering compounds. For this reason, a clean-up step is sometimes required. SPE is preferred as clean up technique because it is fast, requires a low volume of organic solvent and has a low contamination risk. However, the use of SPE has resulted in low recoveries for tetracyclines and sulfonamides [3]. The main aim of this study is to develop an analytical methodology based in a PLE extraction procedure followed by SPE clean up and LC-MS/MS analysis for the quantification of tetracyclines and sulfonamides in sewage sludges. Eight antibiotics from two major antibiotic classes, tetracyclines and sulfonamides, have been selected for this study. Veterinary antibiotic agents oxytetracycline (OTC), tetracycline.HCl (TC), dioxycycline.HCl (DC), chlorotetracycline (CTC), sulfathiazole (STZ), sulfapyridine (SPY), sulfamethazine (SMN) and sulfamethoxazole (SMX) were extracted from sewage sludge samples by pressurized liquid extraction (PLE) using citric acid (pH 4.7) and methanol as extracting buffer. The clean-up of the extract was carried out with Oasis HLB Cartridge solid-phase extraction cartridges. The samples were analyzed with a UHPLC-MS/MS (1290 Infinity LC System and 6430 Triple Quad, Agilent Technologies, USA) instrument operating in positive ion mode and multiple reaction monitoring (MRM) by recording two MRM per compound. The parameters for pressurized solvent extraction were optimized as well as the SPE conditions resulting in recoveries of about 53-85% for the sulfonamides and quantitative for the tetracyclines. The validation of the method and determination of the analytical parameters were carried out by analyzing spiked blank samples (rabbit excrement) at different concentration levels. The method was applied to the analysis of sewage sludges collected from different STPs. |