A core-shell magnetic metal organic framework of type Fe3O4@ZIF-8 for the extraction of tetracycline antibiotics from water samples followed by ultra-HPLC-MS analysis

The authors describe an efficient method for the extraction of tetracycline antibiotics (TCs) from water samples by using a new kind of core-shell adsorbent. It consists of a magnetite (Fe 3 O 4 ) core and a metal-organic framework (type ZIF-8) as the shell. The sorbent has a large specific surface and superparamagnetic response. The sorbent was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption, and X-ray diffraction. The adsorption isotherms, dynamic adsorption, and mechanisms of interactions between tetracycline and sorbent were studied. Various parameters affecting the extraction efficiency were optimized. Following desorption of the TCs with methanol (containing 1% of acetic acid), they were quantified by using ultra-high performance liquid chromatography combined with mass spectrometry. The method has a linear range that extends from 0.5 to 50 ng·L −1 , and the limits of detection for tetracycline, chlortetracycline, and oxytetracycline are 0.125, 0.122 and 0.143 ng·L −1 , respectively. The relative standard deviations of intra-day and inter-day assays range from 3.3% to 8.5%, and from 2.8% to 8.3%, respectively. The recoveries of TCs (at spiking levels of 0.5, 5.0 and 50 ng·L −1 ) are in the range between 78.3% and 93.7%. The method was successfully applied to the determination of TCs in spiked river water, fish pond water, and livestock wastewater.