Mojtaba Amiri - Department of Chemistry, Yazd University, Safaieh, Yazd, Iran-Radiation Application Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
Ali Mohammad Haji Shabani - Department of Chemistry, Yazd University, Safaieh, Yazd, Iran
Shayessteh Dadfarnia - Department of Chemistry, Yazd University, Safaieh, Yazd, Iran

Chromium enters the environment as a result of effluent discharge from different industries, including electroplating, steel, tanning, and oxidative dyeing, and water cooling towers. The toxicity of chromium is a function of the concentration and its oxidation [۱]. Cr(III) is essential for living organisms especially human beings, while Cr(VI) is known as a toxic species that can easily penetrate the cell wall and exert its noxious influence in the cell. Cr(VI) is also known as a cause of different cancer diseases [۲].۲Therefore, the development of sensitive and fast analytical methods for accurate and selective determination of Cr(VI) is important [۳].In this study, nitrogen-doped carbon dots (N-CDs) were synthesized by one-pot microwave treatment of Ranunculus farsicus leaves extract as the carbon source and urea as the nitrogen source and applied as a fluorimetric nanosensor for selective and sensitive determination of Cr(VI) ions. The N-CDs have a relatively uniform size of approximately ۵.۶ nm and good water dispersibility. The N-CDs exhibit strong visible fluorescence and high stability at pH ۷.۰. The fluorescence intensity of the N-CDs would be turned off in the presence of Cr(VI) ions by the mechanism of the inner filter effect (IFT). The limit of detection for Cr(VI) was found to be ۰.۷۵۰ μM and the relative standard deviation (RSD) at ۱۰۰.۰ μM of Cr(VI) was ۵.۶% (n = ۵). The proposed method was successfully applied for the determination of Cr(VI) industrial waste, drinking water, and serum samples.