MoS2 Quantum Dots for On-Line Fluorescence Determination of the Food Additive Allura Red.

This work presents an on-line fluorescence method for the allura red (AR) determination. The method is based on the fluorescence quenching of dots of MoS2 because of their interaction with the non-fluorescence dye. MoS2-dots were synthetized and characterized by spectroscopic techniques and High Resolution Transmission Electronic Microscopy (HR-TEM). The simultaneous injection of the nanomaterial and the dye in a flow injection analysis system allows the determination of allura red at 1.7 x 10(-6) M concentration level with a very good accuracy and precision (Er minor than 10% and RSD lower than 8%) and a sampling frequency of 180 samples per hour. Moreover, the interaction fluomphore-quencher results a dynamic inhibition mechanism. The proposed methodology was applied to the AR analysis in soft beverages and powders for gelatine preparation. Colourant concentrations of 63 +/- 2 mg/L (n = 3) and 0.30 +/- 0.01 mg/g (n = 3) were found, respectively. These results were validated by high performance liquid chromatography technique.