Ultrasound-assisted continuous flow synthesis of natural phenolic-coated Fe3O4 for magnetic solid phase extraction of tetracycline residues in honey.

Waste rubber bark abundant in phenolics can be used to produce an adsorbent for the enrichment and determination of tetracycline. Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) coated with naturally extracted phenolics from waste rubber bark were synthesized for the first time by ultrasound combined with a continuous flow approach. The production of Fe3O4 MNPs with effective contact surface areas (45.3 m2 g-1) was employed as a novel attractive sorbent in magnetic solid phase extraction (MSPE) to selectively preconcentrate oxytetracycline, tetracycline, chlortetracycline, and doxycycline before HPLC-UV analysis. This MSPE-HPLC exhibited wide linear ranges (14.0-260.0 μg kg-1), with low limits of detection (10.0 μg kg-1) and quantitation (14.0-20.0 μg kg-1), and was successfully applied to quantify tetracycline residues in honey samples, with recoveries ranging from 81.3 % to 117.9 %. This method offers a potential alternative for determining tetracycline in food with a high enrichment factor, high precision, and more effective accuracy, selectivity, and sensitivity.