Simultaneous detection of iodide and mercuric ions by nitrogen-sulfur co-doped graphene quantum dots based on flow injection "turn off-on" chemiluminescence analysis system

A simple, rapid and sensitive nitrogen and sulfur co-doped graphene quantum dots (NSGQD) based on flow injection chemiluminescence (FI-CL) technique for the determination of iodide and mercuric ions was reported. Strong CL signal was observed from the reaction of NSGQD and Ce(IV) under acidic condition. The mechanism was investigated by the spectra of CL, fluorescence and UV-vis. Moreover, the CL of the NSGQD-Ce(IV) system was found to be quenched by I-, and then recovered by Hg2+. In this way, a NSGQD-based CL "off-on" nanosensor for the simultaneous detection of I- and Hg2+ was designed. The "turn-off" mode was used for the determination of I- in a linear range of 0.04-3.0 mu M with a detection limit of 4.23 nM. And the linear range for Hg2+ detection based on the "turn-on" process was from 0.3 to 7.0 mu M with a 24.7 nM detection limit. The methods have been applied to the analysis of kelp, tea and water samples.