Molecular Probes pH indicator families, in order of decreasing pKa—Table 20.1

Parent Fluorophore pH Range Typical Measurement
SNARF indicators6.0–8.0Emission ratio 580/640 nm
HPTS (pyranine)7.0–8.0Excitation ratio 450/405 nm
BCECF6.5–7.5Excitation ratio 490/440 nm
Fluoresceins and carboxyfluoresceins6.0–7.2Excitation ratio 490/450 nm
LysoSensor Green DND-1894.5–6.0Single emission 520 nm
Oregon Green dyes4.2–5.7Excitation ratio 510/450 nm or excitation ratio 490/440 nm
LysoSensor Yellow/Blue DND-1603.5–6.0Emission ratio 450/510 nm
pHrodo dyesee below *Single emission 585 nm
* pHrodo succinimidyl ester exhibits a complex pH titration profile. Decreasing pH (from pH 9 to pH 2) produces a continuous (but nonlinear) fluorescence increase. This pH response profile typically changes upon conjugation of the dye to proteins and other biomolecules.
For Research Use Only. Not for use in diagnostic procedures.