Research on Carbon-Derived Fluorescent Probes for Selective Detection of Oxytetracycline in Shellfish Products

A fluorescent probe based on phthalic acid-o-phenylenediamine carbon dots (PP-CDs) was synthesized via a solvent-free method for the specific detection of oxytetracycline (OTC) in shellfish products. Characterization results revealed that the PP-CDs exhibit uniform morphology with an average size of 6.39 ± 1.37 nm, high crystallinity, and abundant surface functional groups. Under optimized conditions, the PP-CDs showed high sensitivity to OTC through a static quenching mechanism, with a detection limit of 0.35 ng mL^-1 (0.76 nmol L^-1 ) and a linear range of 0.4 ~ 50 ng mL^-1. Specificity experiments confirmed that the PP-CDs can selectively recognize OTC among 12 common veterinary drugs, including metronidazole and malachite green. Validation with real shellfish samples showed consistent results with high-performance liquid chromatography (HPLC), indicating the reliability of the method. This probe provides a rapid and cost-effective approach for monitoring OTC residues in seafood, which is of great significance for food safety and environmental protection.