Preparation of shrimp shell derived magnetic biochar coupled with UHPLC-MS/MS for determination of 12 tetracyclines in aquatic products.

Shrimp shell, a waste product from seafood processing, has a great potential to be reused. In this study, a magnetic biochar derived from shrimp shell(MBC-600) was prepared and applied in magnetic solid phase extraction (MSPE) for pretreatment of 12 tetracyclines (TCs) in aquatic products. The characterization and adsorption experiments show that MBC-600 showed good adsorption capacity for 12 TCs due to its high specific surface area (71.30 m/g) and large adsorption capacity(92.08∼141.44 mg/g). The adsorption mechanism of MBC-600 on TCs mainly included π-π interactions, surface complexation, hydrogen bonding, hydrophobic interaction and electrostatic interactions. Under optimized conditions, the MSPE based on MBC-600 coupled with ultra-performance liquid chromatography tandem mass spectrometry(UHPLC-MS/MS) was established for high sensitively determination of TCs from aquatic products. The proposed method showed good linearities (0.5∼200 ng/mL) with R≥0.995, the limits of detection (LODs) and limit of quantification (LOQs) were 0.15∼0.49 μg/kg and 0.50-1.63 μg/kg, respectively. The acceptable recoveries were between 86.6 % and 98.9 % with intra-day and inter-day relative standard deviations ranging from 1.62 % to 3.80 % and 2.41 % to 11.6 %, respectively. The developed green recyclable magnetic biochar material exhibits a facile preparation process with minimal reagent consumption, adhering to green chemistry principles. This dual-function strategy enables sustainable valorization of seafood processing by-products while expanding biochar's applicability in advanced sample pretreatment and ultrasensitive trace analysis systems.