A highly selective colorimetric fluorescent probe for detection of Hg and its application on test strips.

An efficient fluorescent probe Pyr-Rhy based on pyrazole was developed, which can detect Hg in water. Its fluorescence properties were studied by UV-vis and fluorescence spectroscopy, and the study results indicated that this probe can selectively detect Hg complexation reaction, and then cause a remarkable color change from colorless to pink and a strong fluorescence enhancement can be observed. Furthermore, this probe showed high sensitivity with the detection limit down to 2.07 × 10 M, and its stoichiometric ratio toward Hg ions was 1 : 1. The sensing mechanism was investigated by Job's plot H NMR titrations, and FT-IR spectra analysis, which demonstrated a chelation-enhanced fluorescence (CHEF) mechanism. More importantly, obvious color changes of sensor Pyr-Rhy can be observed when it was impregnated on filter paper testing strips and immersed in Hg solution (water as solution), indicating its potential application for trace Hg detection in environmental samples.