A simple method for determination of mercury (II) ions by PNBS-doped carbon dots as a fluorescent probe

A simple and efficient fluorometric method is described for detecting mercury (II) ions. Carbon quantum dots doped with nitrogen, sulfur, phosphorus, and boron were prepared by a one-step hydrothermal method for first time that involves heating of a solution of glucose, thiourea, boric acid, and phosphoric acid in an autoclave simultaneously for 5 h at 200 degrees C. The carbon quantum dots with phosphorus, sulfur, boron, and nitrogen atom (PNBS-CQDs) are a viable probe for fluorometric detection of Hg2+. Unlike CQD-based probes reported so far, the addition of Hg2+ causes a decrease in fluorescence signal (with excitation/emission maxima at 450/530 nm). The probe has a linear response in the 25.0 mu M to 1500.0 mM of Hg2+ concentration range with 5.0 mu M (S/N = 3) and 16.5 mu M for LOD and LOQ, respectively. The developed method was successfully applied for determining the mercury (II) ions in real samples.