CONSTRUCTION OF A SELECTIVE OPTICAL SENSOR FOR NITRITE BASED ON THE GRIESS REACTION

A novel optical sensor for determination of nitrite ions has been developed. The method is based on the diazotization-coupling reaction of nitrite by 3-nitroaniline and 1-naphthylamine in hydrochloric acid solution at pH 1.4 (Griess reaction). The final product has maximum absorption at 346 nm in the membrane. The response characteristic of the sensor including its response mechanism, pH of solution, repeatability and reproducibility, response time and selectivity were evaluated. Conditions for the fabricating the membrane and its function were optimized by central composite design (CCD). The optimized factors were the mass ratio of 3-nitroaniline to 1-naphthylamine as reagents, mass of oleic acid as an additive compound in constructing the membrane and solution pH. The univariate calibration curve was linear in the range of 0.10–4.00 mg Lˉ1 of nitrite. Detection limit of the method for determination of nitrite was 9.5×10-2 mg Lˉ1. The sensor was successfully used to determine nitrite in tap and wastewater samples. In the analysis of the real samples it was found that percent relative standard deviation (RSD %) of the method is low and percent recoveries vary between 103 and 108%.