Red-emitting carbon dots as fluorescent probes for the rapid detection of brilliant blue FCF in foods

To avoid the interference of blue background fluorescence from food substrates, red-emitting carbon dots (R-CDs) were designed for the detection of brilliant blue FCF (BB). The synthesized R-CDs exhibited good photoluminescence stability and emitted red fluorescence at 627 nm. BB exhibits a linear fluorescence quenching effect on R-CDs in the range of 0.2–40 μM with a limit of detection of 84.00 nM. The fluorescence quenching mechanism can be explained by the inner filter effect. Food samples showed no fluorescence signals in the red region. Common substrates also had no visible effect on the fluorescence of the R-CDs. The developed method is practical for the detection of BB in cocktails and beverages without sample pretreatment. Using R-CDs as fluorescent probes, a sensitive, selective, and accurate BB detection method was developed.