文摘
A novel method, solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME), was developed for ultra-preconcentration of 10 antibiotics in different environmental water samples prior to ultra-high performance liquid chromatography-tandem mass spectrometry detection. The optimized results were obtained as follows: after being adjusted to pH 4.0, the water sample was firstly passed through PEP-2 column at 10 mL min−1, and then methanol was used to elute the target analytes for the following steps. Dichloromethane was selected as extraction solvent, and methanol/acetonitrile (1:1, v/v) as dispersive solvent. Under optimal conditions, the calibration curves were linear in the range of 1–1000 ng mL−1 (sulfamethoxazole, cefuroxime axetil), 5–1000 ng mL−1 (tinidazole), 10–1000 ng mL−1 (chloramphenicol), 2-1000 ng mL−1 (levofloxacin oxytetracycline, doxycycline, tetracycline, and ciprofloxacin) and 1–400 ng mL−1 (sulfadiazine) with a good precision. The LOD and LOQ of the method were at very low levels, below 1.67 and 5.57 ng mL−1, respectively. The relative recoveries of the target analytes were in the range from 64.16 % to 99.80 % with relative standard deviations between 0.7 and 8.4 %. The matrix effect of this method showed a great decrease compared with solid-phase extraction and a significant value of enrichment factor (EF) compared with dispersive liquid-liquid microextraction. The developed method was successfully applied to the extraction and analysis of antibiotics in different water samples with satisfactory results. Keywords Antibiotics Dispersive liquid-liquid microextraction Solid-phase extraction Ultra-high performance liquid chromatography-tandem mass spectrometry Water samples