Cane molasses-derived N-doped CQDs for the simultaneous detection of heavy metal ions

The excessive presence of heavy metal ions in food and drinking water poses severe threats to human health and the ecological environment. Therefore, it is crucial to establish highly selective, direct and rapid detection methods. In this work, using cane molasses as the carbon source and ethylenediamine as the nitrogen source, nitrogen-doped carbon quantum dots with high fluorescence performance were synthesized via a green hydrothermal method. By incorporating specific masking agents, this study developed a fluorescent sensor for the rapid, highly sensitive and selective detection of Ag⁺, Co²⁺, Mn²⁺ and Fe³⁺. The sensor exhibits excellent linear ranges with limits of detection of 0.12, 0.53, 0.53 and 0.70 μmol·L⁻¹, respectively. Mechanistic studies reveal that the fluorescence quenching is governed by a static quenching mechanism. Furthermore, Fourier-transform infrared spectroscopy systematically elucidated the specific functional groups interacting with different metal ions, providing a solid structural basis for multi-ion sensing. The successful application of this sensor in human serum and tap water samples demonstrates its outstanding potential for efficient multi-metal ion monitoring.