A Colorimetric and Fluorescent pH Probe for Extremely Acidic Conditions and its Application in pH Test Paper: Fluorescent pH Probe for Extremely Acidic Conditions

Here, we report a highly water-soluble colorimetric and fluorescent pH probe that works in the pH range 0.2-3.0. The probe showed a rapid response, high stability, and excellent reversibility to acidity. Moreover, the fluorescence of probe was not influenced by the existence of high concentration of cations. The pK(a) of probe was calculated to be 2.25 +/- 0.06. Furthermore, the pH test papers coated with the probe exhibited a distinct color change in acidic conditions.