A coumarin-based ratiometric fluorescent sensor for the detection of hydrazine in environmental and biological samples

Abstract

Hydrazine (N₂H₄), a common industrial chemical, poses significant risks to both human health and the environment due to its high toxicity. In this study, a proportional fluorescence sensor (COFB) with coumarin as the fluorophore and 4-bromobutyl as the recognition group was designed and synthesized for the rapid detection of hydrazine residues in the environment. The structure of COFB was confirmed through ¹H NMR, ¹³C NMR and HRMS analysis. Upon reacting with hydrazine, the 4-bromobutyryl group is selectively removed, triggering a fluorescence red-shift that enables ratiometric detection. The sensor COFB demonstrates excellent selectivity, high sensitivity, and robust anti-interference capabilities for hydrazine detection. It operates effectively over a broad linear range (200–600 μM), within a wide pH range (5–9), and with a rapid response time of 22 min. Notably, the detection limit is as low as 0.15 μM (4.8 ppb). The detection mechanism was further elucidated through density functional theory (DFT) calculations. Additionally, COFB was integrated into test strips for visual tracking of hydrazine solution quantification, providing a convenient and practical tool for on-site applications. In biological systems, COFB successfully monitored hydrazine in NCM-460 cells with high sensitivity and selectivity. It also proved effective in detecting hydrazine in soil and water samples from various environmental settings. This study introduces a multifunctional and reliable tool for monitoring hydrazine in the environment, which is of great significance for protecting the ecological environment and promoting social development.