Metal-organic framework modified carbon cloth for electric field enhanced thin film microextraction of sulfonamides in animal-derived food.

Sulfonamides (SAs) were widespread in animal-derived food at trace level, which could trigger hazards to human health. Herein, electric field enhanced thin-film microextraction (EE-TFME) was developed based on carbon cloth (CC) modified with metal-organic frameworks (MOFs) for extraction of SAs (sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidine, sulfamethoxazole and sulfisoxazole), which were a series of polar analytes. MIL-101(Cr) was in situ synthesized on CC via hydrothermal reaction and then was used as positive electrode in EE-TFME for adsorption of SAs. Compared with traditional TFME, EE-TFME shortened extraction equilibrium time from 30 min to 15 min. Coupled with high-performance liquid chromatography (HPLC), the limits of detection (LODs) were 2.5-4.5 µg/L, while the repeatability and intermediate precision was lower than 9.1%. Quantitative determination of SAs in extracts of animal-derived samples, such as honey, pork, chicken and milk, was achieved with recoveries from 81.7% to 114.2%. The developed MOF/CC-based EE-TFME has a great potential in rapid extraction of similar polar or ionic analytes from complex food matrices.