Red-emissive carbon dot as fluorescent probe for the sensitive detection of sunset yellow in foodstuffs.

The highly efficient red-emissive carbon dots (R-CDs) were synthesized from citric acid, polyethyleneimine, and benzil via a facile solvothermal process. The R-CDs displayed maximum fluorescence properties at excitation and emission wavelengths of 550 and 631 nm, respectively, which fall within the red wavelength range. Moreover, the R-CDs exhibited a high fluorescence quantum yield of 11.3 %, and this fluorescence was effectively quenched by Sunset Yellow (SY). Consequently, a novel fluorescent probe was developed for SY detection. This probe exhibited a linear range of 0.085-11.31 μg/mL and limit of detection of 0.026 μg/mL. The R-CDs were validated for SY quantification in various food samples, including carbonate beverages, powdered beverage, cider vinegar, fruit flavored drinks, chocolate, and hard candy samples, achieving recovery rates of 91.2-122 % and a relative standard deviation of 1.0-3.5 %. The synthesized R-CDs therefore show promise for application as a probe for the detection of SY in foods.