Biomass-Derived Fluorescent Probe from Silk Tree Flowers for the Selective and Sensitive Determination of Iron (III) in Water and Food

In this study, fluorescent carbon quantum dots (CQDs) with a high quantum yield of 16.84% were synthesized by utilizing silk tree flowers the as carbon precursor and applied as fluorescent probes for Iron (III) ions (Fe³⁺) detection. The CQDs probe exhibited rapid response to Fe³⁺ (within 2 min) and stable performance across a pH range of 3-10 as well as in high concentration of NaCl solution. Under optimized conditions, the linear range of the probes was from 0 to 35 µmol/L for Fe³⁺ with an ultra-low detection limit of 15 nmol/L and high selectivity against interfering ions. Furthermore, the sensitivity and reliability of the CQDs probe were demonstrated by the determination of Fe³⁺ in complex matrices, including tap water, mineral water, river water, and iron-fortified food products (rice flour, noodles, and biscuits). Owing to its sustainable synthesis and robust analytical performance, the developed probe holds considerable practical potential for the determination of metal ions in environmental and food samples.