The cell-impermeant ratiometric pH indicator
SNARF™-4F 5-(and-6)-carboxylic acid (pK
a of ∼6.4) exhibits a significant pH-dependent emission shift from yellow-orange to deep red fluorescence under acidic and basic conditions, respectively. This pH dependence allows the ratio of the fluorescence intensities from the dye at two emission wavelengths - typically 580 nm and 640 nm - to be used for quantitative determinations of pH.
Learn more about ion indicators including calcium, potassium, pH, and membrane potential indicators ›For Research Use Only. Not for use in diagnostic procedures.