Green/red dual emissive carbon dots for ratiometric fluorescence detection of acid red 18 in food

Abstract

Quantitative determination of hazardous synthetic colorants in food is quite essential for human health. Herein, a ratiometric fluorescence method is developed for sensitive and selective detection of acid red 18 (AR18) using green/red dual emissive carbon dots (g/r-CDs) as probes. The as-synthesized g/r-CDs exhibit two emission peaks at 508 and 610 nm under excitation of a UV light. When AR18 is added, the green fluorescence of g/r-CDs at 508 nm is quenched dramatically due to the strong inner filter effect; in contrast, the red fluorescence at 610 nm decreases much more mildly. The intensity ratio of I 610 /I 508 has a good linearity with the AR18 concentration over the range of 0.05–8.00 μM. A detection limit of 16 nM is obtained, much lower than the most values reported by former analytical methods. Based on the g/r-CD sensor, accurate determination of AR18 in drinks and candy is successfully realized, demonstrating the good practicability of the proposed method for AR18 monitoring in real samples. ● Green/red dual emissive carbon dots (g/r-CDs) are prepared. ● g/r-CDs are used for ratiometric fluorescence assay of acid red 18 in food samples. ● The ratiometric sensor has good sensitivity and selectivity toward acid red 18.