Prepartation of optical sensor based on biobegradable polymers for determination of cations

The development of a novel green optical pH sensor for a wide range pH values is described based on the immobilization of (rubiatinctroum, sour tea, barberry, blackberry) extract on an optically transparent agarose biopolymer. (rubia¬tinctroum, sour¬tea, barberry, blackberry) is famous in Iran. The anthocyanins of (rubiatinctroum-sour tea-barberry and blackberry) were extracted and used as a suitable dye for the preparation of a pH optical sensor, by its immobilization on a transparent agarose film. In an optimized coupling, pH of 11 for rubia¬tinctroum, pH of 2.45 for sour¬tea, pH of7.5 barberry, solution with primary pH for blackberry, and a dye concentration of 100 mg L−1, a sensitive sensor with long term stability was obtained. The sensors responds rapidly to the pH changes in a range of 1–12 with a response time of 5.0 min and repeatability better than %0.3 (RSD). The sensors were mounted in the quartz cells and successfully applied for pH monitoring. No evidence of leaching of the dye or any signal drift was observed.