Porphyrin based metal-organic frameworks as an enhanced fluorescence nanoprobe for highly sensitive detection of sulfite

Development of a facile and effective strategy for highly sensitive detection of sulfite (SO32−) in food is of great significance to human health. Herein, fluorescent porphyrin-based MOFs (PCN-224) was synthesized and further developed as an enhanced fluorescence sensor for SO32− detection. The fluorescence peak of PCN-224 locates at 664 ​nm. In the presence of SO32−, the acid-base reaction between H2PO4− and SO32− promotes the generation of PO43−, thus forming Zr-OP bonds and enhancing the fluorescence intensity of PCN-224 at 664 ​nm. Therefore, H2PO4− is used as an auxiliary agent to construct the sensing system PCN-224/H2PO4−. The fluorescence enhancement of PCN-224/H2PO4− shows a good linear relationship in the range of 0.01–18 ​μM and the limit of detection is as low as 3.8 ​nM. In addition, the constructed PCN-224/H2PO4− sensor system can be successfully used for SO32− detection in the granulated sugar with a recovery ranging from 100.17% to 106.25%, demonstrating the feasibility of PCN-224/H2PO4− nanosensor for SO32− detection in real sample analysis.