Carbon dots-enhanced chemiluminescence method for the sensitive determination of iodide

The nitrogen doped carbon dots regulated by formaldehyde were synthesized using citric acid and melamine by a simple hydrothermal method. The obtained carbon dots (MFCD) significantly enhanced the weak chemiluminescence (CL) reaction of K2Cr2O7 with NaHSO3 by means of energy transform from the intermediate of excited sulphur dioxide (SO2*) and the radiative recombination of oxidant-injected holes and electrons. Interestingly, it was discovered that iodide was effective in enhancing the CL intensity of this system. Based on this finding, the MFCD-based CL system as a sensitive and selective probe was applied for detection of nM levels of iodide ions. Under optimum conditions, the probe had a linear calibration range from 0.03 to 5.0 mu M with a detection limit of 5.6 nM. The developed CL method was applied for the detection of iodide in milk and mineral water samples.