Novel porphyrin covalent organic framework for sensitive fluorescence detection of Cd2+ in tap water and tea beverages.

Covalent organic frameworks (COFs) have emerged as promising materials for heavy metal detection due to their tunable porosity and structural stability. This study synthesized a novel porphyrin-functionalized COF (COF-PPR) and developed a highly sensitive rapid detection method for Cd2+ in tap water and tea beverages based on its fluorescence properties. The COF-PPR exhibited high crystallinity, moderate specific surface area, and excellent chemical/thermal stability. The fluorescence-based Cd2+ detection method demonstrated a low detection limit (1.4 μg/L), wide linear range (5-500 μg/L), and good linearity (R2 = 0.9958). Through optimization of experimental parameters (solvent, material concentration, pH, storage, and reaction time), the method's sensitivity and accuracy were enhanced. It was successfully applied to detect Cd2+ in real samples with recovery rates of 94.6 %-106.0 %, showing satisfactory performance. Mechanistic studies revealed that COF-PPR captures Cd2+ through its porphyrin core cavity. This work provides a novel approach for Cd2+ detection in food-related matrices and offers a valuable material candidate for food safety applications.