One-step green aqueous synthesis of blue light emitting copper nanoclusters for quantitative determination of food color Ponceau 4R

[Display omitted] •The copper nanoclusters (CuNCs) were synthesized by one-step aqueous method.•A blue-emissive fluorescence probe was designed for detection of Ponceau 4R.•Successful applicability in food samples and pharmaceuticals. Depending on the increase of food safety awareness, the quality control of artificial food color Ponceau 4R gain significant due to the adverse effect of dye on human health. For this reason, sensitive, selective, precise, and low cost methods must be developed to meet to need. The copper nanoclusters (CuNCs) were synthesized based on the reaction of copper and L‐cysteine as a reducing and stabilizing agent by the one-pot hydrothermal process and characterized with different methods. The effect of pH, incubation time, and temperature on emission signals of CuNCs were evaluated. The addition of Ponceau 4R into nanocluster solution induced the quenching of fluorescence and possible quenching mechanism was static quenching. Under the optimum conditions, the linearity was achieved between 1.5 and 30 μg mL−1. The selectivity and sensitivity studies showed that developed sensor has excellent selectivity for Ponceau 4R and high sensitivity with low LOD value, 0.028 μg mL−1. The developed fluorescent CuNCs sensor allows to determine of Ponceau 4R in powder drinks, candy, sugar paste, and pharmaceutical syrups samples detection with a high recovery value.