Spectrofluorometric determination of Fe, Pd, and Snions using carbon nanodots derived from hazelnut shells.

Carbon nanodots (CNDs) were synthesized from hazelnut shells using the pyrolysis method in an oven at temperatures ranging from 250 to 400 °C and reaction times between 1 and 3 h. The structural and optical properties of the CNDs, which exhibited strong blue fluorescence under a UV lamp (365 nm), were characterized using UV-vis absorption spectroscopy, fluorescence spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The quantum yield of the CNDs was determined to be between 2.2% and 7.8%. The effect of various cations on the fluorescence spectra of the CNDs was investigated using fluorescence spectrometry. Among the synthesized CNDs, those prepared via pyrolysis for 3 h at 300 °C, 315 °C, and 350 °C (designated as HS300-3, HS315-3, and HS350-3, respectively) exhibited selective fluorescence quenching in the presence of Fe, Sn, and Pd. These CNDs were applied for the determination of Fein tap water and soil samples, while HS315-3 was also employed for the detection of Snand Pdin tap water. The limits of detection (LOD) were 4.5 μg lfor Feand 15.8 μg lfor both Snand Pd. The accuracy of the methods was validated through spiked recovery experiments with tap water samples and by analyzing a certified reference material (CRM-SA-C Sandy Soil C).