Magnetic stir cake sorptive extraction of trace tetracycline antibiotics in food samples: preparation of metal–organic framework-embedded polyHIPE monolithic composites, validation and application

Abstract

In this work, a novel Fe₃O₄@Cu₃(btc)₂-embedded polymerized high internal phase emulsion (Fe₃O₄@HKUST-1-polyHIPE) monolithic cake was synthesized, characterized and used as an adsorbent in the magnetic stir cake sorptive extraction (MSCSE) and determination of tetracycline antibiotics (TCs) in food samples by a combination of with high-performance liquid chromatography–fluorescence detection (HPLC-FLD). The prepared Fe₃O₄@HKUST-1-polyHIPE monolithic composites displayed a strong extraction ability and high column capacity due to enhanced interactions such as π–π interactions, hydrogen bonding, and electrostatic interactions. The extraction and desorption conditions were evaluated, and the calibration curves of four spiked TCs were linear (R² ≥ 0.9991) in the range from 20 to 800 ng mL⁻¹ for milk and egg samples, and 20 to 800 ng g⁻¹ for chicken muscle and kidney samples. The limits of detection and the limits of quantification of the four TCs by using the proposed MSCSE-HPLC-FLD method were in the range of 1.9–4.6 and 5.5–13.9 ng mL⁻¹ for milk and egg samples, and 1.8–3.7 and 5.3–13.0 ng g⁻¹ for chicken muscle and kidney samples, respectively. The recoveries of the target TCs from spiked food samples were in the range from 86.6 to 110.7% with relative standard deviations lower than 7.0%. The proposed method was successfully applied for the determination of these four TCs in milk, egg, chicken muscle, and kidney samples.

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