Green Synthesis of Nitrogen and Sulfur-Doped Carbon Dots for Fluorometric Determination of Pd۲+ and Fe۳+

Iron is an essential transition metal for both plants and animals. However, it is potentially toxic to humans at excess concentration levels. Palladium (II) is also a transition element that plays an important role in cancer treatment, dental crowns, jewelry, and electronics [۱]. Pd(II) is used as a catalyst for many reactions, and the contamination with Pd۲+ requires extensive purification [۲-۳]. Thus, the determination of iron and palladium in environmental and biological samples is important and has been attracted much attention.In this research, A fluorometric nanosensor is designed for the determination of Pd۲+ or Fe۳+ using nitrogen, sulfur carbon dots (N, S-CDs). The N, S-CDs were synthesized by microwave using thyme extract as the carbon source and thiourea as the nitrogen and sulfur source. The prepared N, S-CDs have the strongest excitation/emission peaks at ۳۵۰/۴۵۰ nm and a ۵۳% fluorescence quantum yield. The N, S-CDs were employed as a fluorescent probe for the determination of Pd۲+ with a linear response in the ۰.۱-۲۱۲۰.۰ μM concentration range with the limit of detection (LOD) of ۰.۰۲۹ μM. The probe also responds linearly to Fe۳+ in the ۰.۱-۳۰۰.۰ μM concentration range with a limit of detection of ۰.۰۲۵ μM. The probe was employed for the determination of Fe۳+ in whole milk powder, serum, and urine samples.