Optical pH sensor based on chemical modification of polymer film

A new low-cost pH sensor developed by immobilizing a direct indicator dye t o porous and transparent acetylcellulose film. This sensor was fabricated b y binding alpha-Naphthyl Red and Alizarine Yellow GG to a cellulose acetate film that had previously been subjected to an exhaustive base hydrolysis. The membranes have good durability (>12 months) and a short response time ( <5 s). The method is easy to perform and uses acetylcellulose as a carrier. The reagents used for the activity of the cellulose support are inexpensiv e, nontoxic, and widely available. The Alizarine Yellow GG sensor can be us ed for direct determination of pH in alkaline media without any alkaline er ror, (C) 1999 Academic Press.