A fluorescence-quenching method for quantitative analysis of Ponceau 4R in beverage

CdTe quantum dots was synthesized and used to quantitative analysis of Ponceau 4R in solution. With the excitation wavelength of 380 nm the emission of CdTe quantum dots was quenched obviously by Ponceau 4R. In order to detect Ponceau 4R in mild condition the influences of fluorescence emission wavelength of CdTe quantum dots, pH value, temperature and reaction time were examined to establish the experimental condition. The linear response of the fluorescence intensity of CdTe quantum dots to Ponceau 4R allowed the quantitative analysis of Ponceau 4R in a range of 2.5-25 mu g/mL, and the limit of detection for Ponceau 4R was 0.025 mu g/mL. In addition, the responsive mechanism of this reaction system was investigated in detail by using the modified Stern-Volmer equation and thermodynamic calculation. Particularly, this method was used to quantitatively analyze the real sample, which indicated that this method could be more widely applied in similar samples. (C) 2016 Elsevier Ltd. All rights reserved.