5-(and-6)-Carboxy SNARF-5F Succinimidyl Ester

5-(and-6)-Carboxy SNARF-5F Succinimidyl Ester is an excellent amine-reactive building block that can be readily used for developing SNARF-5F pH probes. SNARF-5F has pKa of ~7.2. It exhibits a significant pH-dependent emission shift from yellow orange to deep red fluorescence under acidic and basic conditions, respectively. The ratioable pH dependent fluorescence intensity change 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 in cells and other biological media.