Green optical sensor based on saffron for monitoring and determination of nitrite in the environmental samples

Optical chemical sensors (optode) have important place in the analytical chemistry research area because of their use in different fields of human knowledge’s. The study of these sensors is also attractive since they allow us to perform in vivo analysis and in situ monitoring. Determination of nitrite ions as a potentially carcinogenic species is in the core attention of the analytical scientists to produce simple, fast, cost effective and environmental friendly approaches. In this work a new simple, low cost, and sensitive optical sensor has been developed for determination of nitrite ions based on the immobilization of saffron (Crocus sativus L.) as a natural sensing reagent on the triacetylcellulose membrane. Selective reaction of the saffron and nitrite ions in the acidic media was monitored photometrically and absorption changes in the wavelength of 440 nm were recorded as analytical signal. The influence of effective variables on the optode performance including triacetylcellulose activation process, concentration of saffron, response time and the effect of ionic strength were studied and optimized. In the optimum conditions, the sensor has good durability and a short response time with linear dynamic range of 1.010-3 – 50.0 μg mL-1 and detection limits of 7.010-4 μg mL-1. Reproduce determinations were done on the solution containing 5.0 μg mL-1 nitrite ion and RSD (n=5) of 4 % was obtained. The effects of various ions and species on the analytical signal were also studied and application of the proposed method in the determination of nitrite ion in many real samples such as tap and well water gave satisfactory results.