Graphene quantum dots as a fluorescence-quenching probe for quantitative analysis of Ponceau 4R solution

Ponceau 4R is widely used as a colorant in China. However Ponceau 4R poses potential risks to human health, especially when consumed in excess amounts. In this paper, quantitative analysis of Ponceau 4R in solution was achieved based on the fluorescence quenching of graphene quantum dots. UV absorption spectra and calculations based on a modified Stern–Volmer curve were employed to study the fluorescence quenching mechanism of this system. All results indicate that it is a static quenching process. Furthermore, the effect of pH, temperature and reaction times on the fluorescence intensity of GQDs with Ponceau 4R was studied. Under the optimal conditions, the linear response of the fluorescence intensity of GQDS to the concentration of Ponceau 4R allowed the quantitative analysis of Ponceau 4R in a range of 5–150 μg mL−1, and the limit of detection was 2.57 μg mL−1. And the low detection limit could reach 8.32 ng mL−1 by using more diluted GQDs. Particularly, this method was used to quantitatively analyze real samples, indicating that this method could be more widely applied to similar samples.