FD&C Yellow No. 5 (tartrazine) degradation via reactive oxygen species triggered by TiO2 and Au/TiO2 nanoparticles exposed to simulated sunlight.
When exposed to light, TiO2 nanoparticles (NPs) become photoactivated and create electron/hole pairs as well as reactive oxygen species (ROS). We examined the ROS production and degradation of a widely used azo dye, FD&C Yellow No. 5 (tartrazine), triggered by photoactivated TiO2 NPs. Degradation was found to follow pseudo-first order reaction kinetics where the rate constant increased with TiO2 NP concentration. Depositing Au on the surface of TiO2 largely enhanced electron transfer and ROS generation, which consequently accelerated dye degradation. Alkaline conditions promoted ROS generation and dye degradation. Results from electron spin resonance spin-trap spectroscopy suggested that at pH 7.4, both hydroxyl radical (•OH) and singlet oxygen ((1)O2) were responsible for dye discoloration, whereas at pH 5, the consumption of (1)O2 became dominant. Implications for dye degradation in foods and other consumer products that contain both TiO2 and FD&C Yellow No. 5 as ingredients are discussed.
Division of Analytical Chemistry and ‡Division of Bioanalytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , College Park, Maryland 20740, United States.
Meng
M
Li
Weiwei
W
He
Yi
Y
Liu
Haohao
H
Wu
Wayne G
WG
Wamer
Y Martin
YM
Lo
Jun-Jie
JJ
Yin
D004396:Coloring Agents / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D007700:Kinetics; D053758:Nanoparticles / Q000737:chemistry*; D010782:Photolysis / Q000528:radiation effects*; D017382:Reactive Oxygen Species / Q000737:chemistry*; D013472:Sunlight; D013645:Tartrazine / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry
D004396:Coloring Agents; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D006046:Gold; D014025:Titanium; D013645:Tartrazine
ESR; FD&C Yellow No. 5; ROS; TiO2 nanoparticles; color degradation; tartrazine