A novel chemosensor based on graphitic carbon nitride quantum dots and potassium ferricyanide chemiluminescence system for Hg(II) ion detection

• Graphitic carbon nitride quantum dots (g-CNQDs) were prepared by a simple method.
• K3Fe(CN)6 was used as an oxidant in chemiluminescence (CL) system of g-CNQDs.
• Hg(II) ion has a diminishing effect on the g-CNQDs–K3Fe(CN)6 CL system.
• A simple and sensitive chemosensor was constructed for Hg(II) ion detection.
• The method was successfully applied to determine Hg(II) ion in various real samples.

In this research, graphitic carbon nitride quantum dots (g-CNQDs) were prepared by a simple and one-step microwave-assisted approach and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The chemiluminescence (CL) emission of the synthesized g-CNQDs induced by K3Fe(CN)6 as an oxidant along with the CL mechanism were investigated. Based on the diminishing effect of Hg(II) ion on the g-CNQDs–K3Fe(CN)6 CL system, a simple and sensitive chemosensor was constructed for Hg(II) ion detection in aqueous solutions. A response surface methodology was used to optimize the experimental parameters affecting the analytical signal. Under the optimized experimental conditions, the calibration graph was linear in the range of 0.25–10 ng mL−1 with a detection limit of 0.08 ng mL–1. The inter-day and intra-day relative standard deviations for six replicate determinations of 4 ng mL–1 Hg(II) ion were 3.4% and 2.8%, respectively. The developed method was successfully applied for the selective and sensitive determination of Hg(II) in water and food samples with recoveries in the range of 95.7–102.8% for the spiked samples. The accuracy of the method was evaluated by analyzing a certified reference material (SRM 1566b).

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