In this work, a method for the analysis of fluoroquinolone antibiotics using microwave-assisted micellar extraction combined with liquid chromatography-mass spectrometry detection has been developed. Different surfactants were tested for use as extractants in the isolation of the analytes from solid samples, and several experimental designs were evaluated for the determination and optimization of the variables that affect recovery from the matrix. Under optimal conditions, we obtained recoveries greater than 73% with relative standard deviations below 8%. Compounds were detected by liquid chromatography-electrospray ionization tandem mass spectrometry with detection limits between 0.15 and 0.55 ng g(-1) and quantification limits between 0.49 and 1.85 ng g(-1) . Finally, the optimized method was applied in the determination of antibiotics in real solid samples. Four fluoroquinolones (levofloxacin, norfloxacin, ciprofloxacin and enrofloxacin) were found in coastal marine sediments taken close to a marine outfall and in sewage sludge samples from a wastewater treatment plant. Concentrations ranged between 0.81 and 34.3 ng g(-1) in the sediments and 3.43 and 206.1 ng g(-1) in the sludge.
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