Ratiometric Fluorescence Detection of Tetracycline in Milk and Tap Water with Smartphone Assistance for Visual pH Sensing Using Innovative Dual-Emissive Phosphorus-Doped Carbon Dots

Tetracycline (TC) is a common antibiotic that poses risks to human and animal health when present in samples. pH is a crucial parameter for assessing water quality and food safety. The innovative ratiometric probe, designed based on dual-emissive phosphorus-doped carbon dots (DE-P-CDs), was synthesized through a green hydrothermal process. The sensor exhibited high analytical performance toward TC detection with a LOD of 5.78 μM and 6.18 μM, respectively, and visual pH detection. Furthermore, the DE-P-CDs were employed for visual pH sensing, with the solution color smoothly changing with variations in pH. The color transitioned from red to orange, green to dark green, and blue to dark blue, facilitating easy visual observation. This probe proves to be a versatile tool for detecting TC in milk and tap water samples, with visual capabilities for pH. Two metric tools which were AGREE and BAGI were also used to evaluate the method's greenness. The evaluation affirmed its outstanding environmental friendliness. It represents a valuable contribution to the fields of analytical chemistry, food, and environmental monitoring.