Fluorescence based visual sensing of cesium ions enabled by space-confined converting enriched cesium ions to CsPbBr3 nanocrystals in crown ether functionalized mesoporous silica.

Portable fluorescence-based Cs+ radionuclide sensing has received great concerns yet challenged by interference in complex sample matrices. Herein, a reliable method was established by in situ converting the preconcentrated Cs+ to CsPbBr 3 perovskite nanocrystals in mesoporous silica modified with dibenzo 24-crown-8 ethers (DB24C8E-SiO 2), which combined the selective extraction of Cs+ with in situ fluorescence derivatization to achieve good anti-interference ability. The high adsorption capacity (49.5 mg g−1) of DB24C8E-SiO 2 for Cs+ and elution-free operation enabled enrichment factor up to 4500, which was conducive to reducing the limit of detection (LOD) for Cs+. By this method, the fluorescence intensity linearly increased with the Cs+ concentration from 0.050 μg mL−1 to 100 μg mL−1 with an LOD of 0.017 μg mL−1 (S/N = 3). The concentration of Cs+ in seawater sample was detected to be 0.056 μg mL−1. The recoveries of Cs+ in spiked samples remained above 88.90 % and the relative standard deviations were less than 12.06 %. In addition, the relative errors of this method were within ±13.2 % compared with the result from atomic absorption spectrometry. The study demonstrated the high potential of the method for removal and portable detection of Cs+. [Display omitted] • Solid phase extraction coupled with in situ perovskite growth are realized for highly selective Cs+ sensing. • On site fluorescence derivatization enables ultrahigh enrichment factor and low detection limit. • Fluorescence turn-on and wavelength-shift responses facilitate visual sensing. [ABSTRACT FROM AUTHOR]