Boron-doped graphitic carbon nitride as a novel fluorescent probe for mercury(ii) and iron(iii): a circuit logic gate mimic

Abstract

The detection and determination of metal cations in different real samples are important matters in various fields of experimental science. Herein, graphitic carbon nitride (g-C₃N₄) doped with boron was facilely prepared and shown to be a practical fluorescent probe for the detection and measurement of mercury and ferric ions in real samples. The nanomaterial was characterized by XRD, FT-IR, SEM, elemental mapping, and N₂ adsorption–desorption techniques. Fluorescence of the boron-doped g-C₃N₄, with a 280/348 nm excitation/emission maximum, is quenched by mercury and ferric ions. The quenching effect was used to design assays with detection limits of 185 nM (for Hg²⁺) and 154 nM (for Fe³⁺) and worked in the pH range 7–10, in aqueous solutions. The mechanism of quenching was investigated by using the Stern–Volmer equation. The probe was used to determine the Fe³⁺ and Hg²⁺ levels in spinach and tuna fish, respectively, and the results were compared with ICP-OES. Quenching by Fe³⁺ can be reversed by sodium hexametaphosphate (SHMP), as a masking agent for Fe³⁺. Therefore, a circuit logic system was developed with Fe³⁺, Hg²⁺, and SHMP as inputs, and the quenched signal as the output.