Blue fluorescent carbon dots doped with nitrogen and sulfur as a dual-functional fluorescent probe for the detection of Hg2+ and chloramphenicol

Mercury ions (Hg²⁺) contamination and chloramphenicol (CAP) residue in food pose significant threats to human health and food safety. This study explores the use of nitrogen and sulfur-doped blue fluorescent carbon dots (B-CDs) as a fluorescence-based sensor for the detection of chloramphenicol (CAP) and mercury ions (Hg²⁺), which are critical contaminants in both environmental and food safety contexts. B-CDs were synthesized and characterized, and their performance as sensors was evaluated through fluorescence intensity measurements in response to varying concentrations of CAP and Hg²⁺. The linear correlation coefficients (R²) for both CAP and Hg²⁺ detection were 0.9958 and 0.9944, respectively, demonstrating a strong linear relationship between fluorescence intensity and analyte concentration. The detection limits for CAP and Hg²⁺ were calculated as 0.31 μM/L and 1.75 μM/L, highlighting the high sensitivity of B-CDs. Additionally, the sensor's performance was tested under various conditions, including changes in temperature, salinity, and light exposure, showing excellent stability and photostability. This work provides a simple, efficient, and highly sensitive sensor for detecting trace amounts of CAP and Hg²⁺, with significant potential for applications in environmental monitoring and food safety. The findings may pave the way for the development of more advanced, cost-effective, and portable fluorescence-based sensors for broader analytical purposes.