Visual detection of nitrite via the multicolor cellulose-based rare-earth fluorescent materials

Abstract

Excessive nitrite has posed serious threats to the environment, human beings, and public security. In this work, multicolor cellulose-based fluorescent probes were prepared from the cellulose-based polymeric sensitizer and rare-earth metal ions for nitrite detection. The sensitizer contained two typical groups: terpyridine and quaternary ammonium. Terpyridine sensitized rare-earth metal ions, while quaternary ammonium granted good water solubility and intrinsic blue fluorescence to the cellulose-based fluorescent materials. The emission spectra of the fluorescent materials can be finely regulated by adjusting the concentration of rare-earth metal ions, resulting in different luminescent materials with blue, green, red and white fluorescence. This is a feature unattainable with conventional single-signal probes. A colorimetric approach based on the intrinsic blue fluorescence of quaternary ammonium and the sensitized rare-earth metal ions was established to detect nitrite in different modes. The materials exhibited exceptional performance, including a low detection limit of 12.4 μM (surpassing the WHO guideline of 65.22 μM for nitrite in drinking water) and high selectivity among 13 anions. With their exceptional specificity, low limit of detection, and convenient operation, these ratiometric probes show great potential for applications in food safety assessment, drinking water quality monitoring, and environmental monitoring.