Abstract: Based on the fluorescence quenching effect of CdTe quan tum dots by amaranth, we used fluorescence quenching method of CdTe quantum dots to detect the concentration of amaranth, and analyzed its reaction mechanism. T he results show that the linear range of detection is from 4.14×10^-6 mol/ L to 9.10×10^-5 mol/L, and the minimum detection limit is 4.81×10^-9 mol/L. The fluorescence quenching constant is 1.91×10¹² L/(mol·s) , the slope of SternVolmer curve at high temperature is lower than that of l ow temperature, and UVVis absorption spectra show that the process is a static quenching process. According to thermodynamics calculation, the thermodynamic p arameters Δ H=1.063 kJ/mol, Δ S=91.36 J/(mol·K) and Δ G=-26.62 kJ/mol, i.e., and the process is an endothermic and spontaneous proc ess.

Key words: fluorescence quenching, CdTe quantum dot, amaranth, food additive