Development of Optical pH Sensor Based on Curcumin Reagent Immobilized in Sol-gel/Chitosan Melamine Hybrid Matrices)

An optical pH sensor has been developed using curcumin reagent immobilized in sol-gel/chitosan-melamine hybrid matrices. The optical pH sensor gave a linear response at range of pH 9-13 (R-2 = 0.9846). Relative standard deviation (RSD) values of reproducibility were 7.38%-9.65%, while RSD values of repeatability were 2.18%-4.72%. Good photostability was obtained for immobilized curcumin reagent when the films were kept in dark surrounding with RSD value 3.69% for 3 weeks. No hysteresis effect was observed when the sensor was used to measure pH in cycle from pH 2-12-2. The response time of the sensor was within 10-20 seconds. Determination of pH value in real samples by using pH sensor developed in this study showed no significance differences when compared with results obtained by using conventional pH meter.