Rapid Visual Detection of Sulfur Dioxide Residues in Food by Cdte Quantum Dots-Loaded Alginate Hydrogel Beads

Abstract

A rapid visual detection of sulfur dioxide residues by CdTe quantum dots-loaded alginate hydrogel (CdTe QDs-AH) beads is developed. In the newly designed reaction device, under the condition of adding citric acid and heating at 70°C for 20 min, the sulfites in the solution are transformed into SO2 gas, which can then quench the fluorescence of a CdTe QDs-AH bead fixed above the solution. The amount of sulfur dioxide residue can be accurately determined according to the linear relationship between the difference the average fluorescence brightness (L0-L) of the CdTe QDs-AH bead and the concentration of SO2. It also can be semi-quantitatively estimated by naked-eye observation. This novel method, which has been successfully applied to 5 kinds of food substrates, is simpler, more portable, and economical and does not require complex pretreatment. It will provide a new idea for the development of on-site real-time detection in food control.

Keywords: Sulfur dioxide residues, Visual detection, Hydrogel beads, CdTe quantum dots, alginate