Research on highly sensitive detection technology of nitrite based on a novel colorimetric fluorescent probe

Nitrite (NO₂^-), a natural component of the nitrogen cycle, poses significant risks to both ecosystems and human health when present as a pollutant. Hence, it is essential to develop detection methods with high selectivity, sensitivity, and rapid response for measuring nitrite levels in water. This study introduces a novel colorimetric fluorescent probe PQ-N, which specifically recognizes NO₂^- in diverse environments including water, soil, and food. The probe features ultra-low detection limits of 0.16 μM (for fluorescence spectroscopy) and 0.81 μM (for absorption spectroscopy), a linear detection range of 0-10 μM, as well as strong resistance to interference from complex environmental matrices. Moreover, a new sensing platform based on test strips combined with smartphone-assisted chemical dosimeters is established, enhancing the convenience and reliability of on-site nitrite detection. Validation using real samples shows agreement with national standard methods, confirming the probe's practical applicability. This research offers an effective and accurate tool for nitrite detection, contributing valuable support for ecological safety assessments.