Amao, Yutaka published the artcileAn optical sensor with the combination of colorimetric change of α-naphtholphthalein and internal reference luminescent dye for CO2 in water, Computed Properties of 596-01-0, the publication is Sensors and Actuators, B: Chemical (2005), 107(2), 861-865, database is CAplus.
A new optical CO2 sensor based on luminescence intensity changes of tetraphenylporphyrin (TPP) due to the absorption change of pH indicator dye (α-naphtholphthalein) with CO2 is developed and its CO2 sensing properties in pure H2O were studied. The observed luminescence intensity from TPP at 650 nm increased with increasing the CO2 concentration in pure H2O. The ratio I100/I0, where I0 and I100 represent the detected luminescence intensities from a layer exposed to 100% Ar and 100% CO2, resp., that the authors takes the sensitivity of the sensor is 430. The response times of the sensing film are 42.6 s for switching from Ar to CO2, and 88.8 s for switching from CO2 to Ar in pure H2O. The signal changes are fully reversible and no hysteresis is observed during the measurements.
Sensors and Actuators, B: Chemical published new progress about 596-01-0. 596-01-0 belongs to benzofurans, auxiliary class Benzofuran,Naphthalene,Alcohol,Ester, name is 3,3-Bis(4-hydroxynaphthalen-1-yl)isobenzofuran-1(3H)-one, and the molecular formula is C28H18O4, Computed Properties of 596-01-0.
Referemce:
https://en.wikipedia.org/wiki/Benzofuran,
Benzofuran | C8H6O – PubChem