Cell-Impermeable Ratio pH IndicatorSNARF™-5F 5-(and-6)-Carboxylic Acids(pK_a of ∼7.2) show significant pH-dependent emission wavelength changes from yellow-orange to deep red fluorescence under acidic and alkaline conditions, respectively. This pH dependence allows the quantitative determination of pH using the ratio of the dye's fluorescence intensity at two emission wavelengths (typically 580 nm and 640 nm).

Learn more about ion indicators, including calcium, potassium, pH, and membrane potential indicators›