LAUSR

Two sensitive and ratiometric fluorescent probes (probe I and probe II) were developed for the detection of fluoride ions. Probe I can detect fluoride ions quantitatively within a range of 0–6 μM and a detection limit of 73 nM, while probe II has a range of 0–40 μM and a detection limit of 138 nM. The test strips from probe I are quickly able to recognize F– (5 min) inside of the F– safety level in drinking water (1.0 mg/L, ∼5 μM) under 254 nm ultraviolet light, and the test strips from probe II quickly recognize F– (12 min) in dangerously high F– levels in water (4.0 mg/L, ∼21 μM) under 254 nm ultraviolet light. This combination of fluorescent paper sensors from probe I and probe II can be used as a simple and convenient tool to determine whether water is safe to drink or dangerous.