An Innovative Selective Fluorescence Sensor for Quantification of Hazardous Food Colorant Allura Red in Beverages Using Nitrogen-Doped Carbon Quantum Dots

An innovative simple, sensitive, and selective method has been developed and validated for quantification of hazardous Allura red (AR, E129) dye in beverages. Allura red (AR) is a synthetic dye that is commonly used in the food industry to give foods a bright and appealing color. The method is based on microwave-assistant nitrogen-doped carbon quantum dots (N@CQDs) from a very cheap source with a high quantum yield equal to (36.60%). The mechanism of the reaction is based on an ion-pair association complex between AR and nitrogen-doped carbon quantum dots (N@CQDs) at pH 3.2. The reaction between AR and N@CQDs led to a quenching effect of the fluorescence intensity of N@CQDs at 445 nm after excitation at 350 nm. Moreover, the quantum method's linearity covered the range between 0.07 and 10.0 & mu;g mL(- 1) with a regression coefficient is 0.9992. The presented work has been validated by ICH criteria. High-resolution transmission electron microscopy (HR-TEM), X-ray photon spectroscopy (XPS), Zeta potential measurements, fluorescence, UV-VIS, and FTIR spectroscopy have all been used to fully characterize of the N@CQDs. The N@CQDs were successfully utilized in different applications (beverages) with high accuracy.

Automated summary

An innovative method using microwave-assisted nitrogen-doped carbon quantum dots (N@CQDs) was developed and validated for quantifying Allura red (AR, E129) dye in beverages. The method is based on the ion-pair association complex between AR and N@CQDs at pH 3.2, which leads to a quenching effect of N@CQDs fluorescence. The method showed a linear range of 0.07-10.0 µg mL(-1) with a regression coefficient of 0.9992. HR-TEM, XPS, Zeta potential measurements, and spectroscopic techniques were used to fully characterize the N@CQDs.