Optical sensor for high pH values Original Research Article

A new optical pH sensor for high pH values has been developed by covalently immobilizing Thiazole Yellow on an optically transparent triacetylcellulose membrane, which had been previously hydrolyzed. The advantageous features of the sensor include (a) the ability to respond at high pH values (12.0–13.5), where glass electrodes show an alkaline error, (b) a rapid equilibration time, (c) high reproducibility, (d) long term stability, (e) high sensitivity and (f) ease of fabrication.