Abstract: Based on the regulation of Pb(II) on the enzyme-like activity of carbon dots co-doped with copper and iodine (Cu, I-CDs), a novel, simple and sensitive colorimetric probe was established for the determination of Pb(II) in tea samples. The kinetic parameters of Cu, I-CD peroxidase-like activity were well fitted to the Michaelis-Menten equation. When it was adsorbed on the surface of Cu, I-CDs, Pb(II) could promote the oxidation of the substrate 3,3’,5,5’-tetramethylbenzidine (TMB). The concentration of Pb(II) in the range of 0.27–27.02 mg/L showed a good linear relationship with the formation of oxidized TMB (oxTMB). The detection limit of the developed method was 34.3 μg/L, and the spiked recoveries for actual tea samples were in the range of 92.41%–101.85%. These figures of merit meet the requirements of the national standard GB 5009.12-2017. In conclusion, this method is simple, stable, and specific, and its detection limit is lower than the country’s limit for Pb(II) content in foods.

Key words: lead; carbon dots co-doped with copper and iodine; peroxidase mimic; colorimetric probe; tea