mercury (ii) detection using nitrogen and sulfur co-doped carbon quantumdots and fluorescence quenching assay

Mercury is a highly toxic and potentially bioaccumulative heavy metal ion that can cause severehealth problems in humans even at very low concentrations. thus, the development of a simple,rapid, and sensitive assay for the effective detection of mercury ions at trace levels is of greatimportance. here, nitrogen and sulfur co-doped carbon quantum dots (n,s-cqd) were synthesizedby hydrothermal treatment of chitosan in the presence of thiourea and citric acid with a quantumyield (qy) up to 33.0 % and used as a selective fluorescent probe to detect mercury ions (hg2+).the synthesized n,s-cqd showed ultrasensitive ability to detect hg2+ ions in the presence of 11interfering metal ions, with a low detection limit (~4 nm) over a wide linear range from ~5- 160nm. the sensing performance of n,s-cqd probe in real sample applications was evaluated by thedetection of hg2+ in lake water samples.