Determination of trace hydrogen sulfide by using the permanganate induced chemiluminescence of carbon dots

Carbon dots (C-dots) were prepared in aqueous solution by a one-step ultrasonic approach, and the absorption and fluorescence spectra were acquired. It is found that acidic solutions of potassium permanganate cause C-dots to produce green and red chemiluminescence (CL) peaking at 520 nm and 620 nm, respectively, and that CL intensity is further enhanced on addition of sulfide. A mechanism leading to this enhancement is suggested. After optimizing the reaction conditions, the CL-based calibration plot is linear in the 1.0 to 100 mu M sulfide concentration range, with a 0.2 mu M detection limit (at a signal-to-noise ratio of 3). The relative standard deviation is 1.7 % for the determination of a 10 mu M solution of sulfide. The method was employed to quantify trace levels of sulfide in water samples.