Time-gated fluorescence sensor for trace water content determination in organic solvents based on covalently immobilized europium ternary complex

A time-gated fluorescence sensor for water content determination in organic solvents was proposed in this paper. A europium ternary complex (ETC) was synthesized and used as the fluorescence indicator in the fabrication of the fluorescence water sensor. To prevent leakage of the fluorophore, ETC was photo-copolymerized with acrylamide, (2-hydroxyethyl)methacrylate, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and triethylene glycol dimethacrylate on a glass surface treated with a silanizing agent. The ETC has long life-time fluorescence, and time-gated fluorescence intensity was used in this paper instead of fluorescence intensity. The time-gated fluorescence intensity of ETC decreased with increasing of water content in organic solvents. In the range of 0.0–8.0% (v/v), the time-gated fluorescence intensity of ETC changed as a linear function of water content. The detection limits were 0.056%, 0.042%, and 0.033% for ethanol, tetrahydrofuran, and 1,4-dioxane, respectively. The sensor exhibited satisfactory reproducibility, reversibility, and a short response time. The sensing membrane was found to have a lifetime of at least one mouth.