Nitrogen and sulfur co-doped carbon quantum dots fluorescence quenching assay for detection of mercury (II)

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2023-05, Vol.293, p.122448, Article 122448
• Main Authors: Chaghaghazardi, Mosayeb, Kashanian, Soheila, Nazari, Maryam, Omidfar, Kobra, Joseph, Yvonne, Rahimi, Parvaneh
• Format: Article
• Language: English
• Subjects: Carbon quantum dots; Chitosan; Fluorescence quenching; Mercury sensor; Nitrogen and sulphur doping
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2023.122448

[Display omitted] •Nitrogen and sulfur co-doped carbon quantum dots were hydrothermally synthesized using chitosan, thiourea, and citric acid.•The calculated quantum yield of synthesized carbon quantum dots is relatively high (up to 33.0 %).•The synthesized carbon quantum dots were used as a fluorescent probe to detect Hg2+ in water with a low detection limit.•The effect of interfering metal ions was investigated; also acceptable recoveries were obtained in real samples. Mercury is a highly toxic and potentially bioaccumulative heavy metal ion that can cause severe health 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 great importance. Here, nitrogen and sulfur co-doped carbon quantum dots (N,S-CQD) were synthesized by a simple hydrothermal treatment of chitosan in the presence of thiourea and citric acid with a quantum yield (QY) up to 33.0 % and used as a selective fluorescent probe to detect mercury ions (Hg2+). The effect of pH, ionic strength, and time on the fluorescence intensity of N,S-CQD were investigated and optimized. The synthesized N,S-CQD showed ultrasensitive ability to detect Hg2+ ions in the water samples, also in the presence of 11 interfering metal ions, with a low detection limit (∼4 nM) over a wide linear range from ∼5–160 nM. The sensing performance of N,S-CQD probe in real sample applications was evaluated by the detection of Hg2+ in lake water samples, which confirmed its potential application in environmental analysis.