Abstract
The new enhancement in the determination of pH using optical fiber system is described here. This work uses the membrane made of cellulose acetate membrane for reagent immobilization and congo red (pK a 3.7) and neutral red (pK a 7.2) as pH indicators. An effective covalent chemical binding procedure is used to immobilize the indicators. The response time, reversibility, linear range, reproducibility, and long-term stability of fiber optic sensor with congo red as well as neutral red have been determined. The linear range measured for the sensor based on the congo red and neutral red is 4.2–6.3 and 4.1–9.0, respectively. The response time of sensor membrane is measured by varying the substance pH values between 11.0 and 2.0.
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