A Chemiluminescence Method Based on Cl, S, N Co-Doped Carbon Dots for the Rapid Determination of Folic Acid in Foods

Folic acid (FA) is a crucial B vitamin for cell formation and maintenance, and its deficiency can lead to severe health disorders, highlighting the importance for accurate FA detection. Chemiluminescence (CL) provides a highly sensitive analytical approach, characterized by simple instrumentation, high accuracy, and low background interference. However, traditional CL techniques are often limited by weak signal intensity and poor robustness. This study presents a novel CL system using well-defined fluorescent Cl, S, N co-doped carbon dots (ClSN-CDs) integrated into the H₂O₂-KBrO₃ system. Under acidic conditions, the synergistic effect of H₂O₂ and KBrO₃ induced ClSN-CDs to emit a strong CL signal, with the emitting species identified as excited-state ClSN-CDs. Trace amounts of FA significantly quenched the CL intensity of the ClSN-CDs-H₂O₂-KBrO₃ system, enabling rapid, sensitive, and selective FA detection. The system demonstrated a linear response to FA concentrations ranging from 0.02 to 1.0 μM, with a detection limit of 3.1 nM. Selectivity and recovery studies validated the system's robust analytical performance. Mechanistic investigations revealed that the CL reaction involved reactive oxygen species (ROS), and FA-mediated ROS consumption led to luminescence suppression.