Rapid and specific detection of copper chlorophyllin in food with turn-on fluorescence signal

The rapid detection of copper chlorophyllin (Cu-Chl) is crucial for ensuring food safety. A key challenge in achieving specific detection is the effective elimination of interference from substances such as natural chlorophyll. Herein, a rapid fluorescence method for detecting Cu-Chl is developed. KMnO₄ is employed to efficiently decompose Cu-Chl, releasing Cu²⁺ while simultaneously neutralizing the interference from natural chlorophyll. Inspired by the principles of fluorescent nanoparticle synthesis, fluorescent Cu nanoclusters were developed by utilizing p-mercaptobenzoic acid as a ligand to react with Cu²⁺. The "turn-on" fluorescence signal demonstrates excellent stability and robust resistance to non-specific quenching. The concentration of Cu-Chl can be rapidly quantified by measuring the resulting fluorescence intensity. This method achieves a detection limit of 15.0 μg/g, with recoveries higher than 91.2% in ice cream, beverages and biscuit. The validation results from ICP-MS demonstrate that the fluorescent assay exhibits good applicability in rapid detection of Cu-Chl in foods.