مشخصات پژوهش

In recent years, environmental pollution by nitrogen compounds, such as nitrite, nitrate, ammonia, and organic compounds [1], has attracted considerable attention. Among the above-mentioned compounds, nitrite (NO2¯) is known as the most hazardous and important anionic analyte. Nitrites are largely used in food preservatives, fertilizers, detergents, wood pulping and dyes and thus can be released into the environment, leading to the contamination of soils, groundwater, rivers, and lakes. According to the World Health Organization (WHO), the maximum permissible amount of nitrite ions in drinking water is 3 mg L-1 [2] . Thus, sensitive, selective, and precise methods are required for the determination of nitrite ions in water samples. In this work, a simple method has been developed for determination of nitrite in different aqueous samples based on spectrophotometry and colorimetric methods. The method is based on the reaction of nitrite with potassium iodide in acid medium to liberate iodine. This liberated iodine reacts with starch adhesive to form a dark blue complex with a maximum absorption of 570 nm. The effect of different parameters on the proposed method was investigated and optimized. Under the optimal conditions, the calibration graph was linear in the range of 0.05-1 mg L-1 with the limit of detection (LOD) of 0.02 mg L-1. Relative standard deviation for determination of 0.3 and 0.5 mg L-1 of nitrite was obtained 7.5% and 5.5, respectively, for six replicates. After investigating of interference of common cations and anions, the proposed method was successfully utilized for the determination of nitrite ions in different water samples (rain water and tap water) with satisfactory recovery ranged from 93% to 95%.