Chemiluminescence of doped carbon dots with H2O2-KMnO4 system for the detection of Cu2+ and tannin.

The carbon dots doped with chlorine and phosphorus (CDs-Cl,P) were used as chemiluminescence (CL) reagent for the sensitive detection of copper ions (Cu2+) and tannin (TA). The CDs-Cl,P was found to strongly enhance the reaction of H2O2 and KMnO4 in alkaline medium. The enhanced CL behavior of CDs-Cl,P was investigated and it was found that some radicals such as •OH, •O2- and 1O2 appeared in the CL reaction process. The participation of Cu2+ could result in an enhanced CL intensity of the CDs-Cl,P-H2O2-KMnO4 system due to the Cu2+-catalyzed decomposition of H2O2 resulting in more •OH generation. Therefore, the CDs-Cl,P-H2O2-KMnO4 system was used to selectively quantify Cu2+ in solution by CL emission. A linear increase was observed between CL intensity and Cu2+ concentration. The CDs-Cl,P-H2O2-KMnO4 system allowed the detection of Cu2+ down to lower concentration of 0.1 μM with a linear range of 0.2-60.0 μM. Moreover, TA as a common polyphenolic compound, could selectively decrease the CL signal of the CDs-Cl,P-H2O2-KMnO4-Cu2+ system due to its complexation with Cu2+. On this basis, the CL assay for TA was also developed. The detection limit was 0.14 μM and the linear range was from 5.0 μM to 100.0 μM. The proposed method was successfully applied to the determination of Cu2+ and TA in water, rice dumplings leaves, sodium copper chlorophyllin and wine samples with satisfactory results.