The determination of nitrite is of increasing interest in a variety of fields such as food, water and environmental samples. Nitrite and nitrate ions participate in several important environmental transformations involving nitrogen. The toxicity of nitrite is primarily due to the fact that it can react with secondary or tertiary amines present in the human body to form nitrosamines, which are known to be carcinogens and mutagenic. Traces of nitrite in drinking water may lead to methemoglobinemia and with long term exposure is a possible cancer risk. It is well known that the nitrite ion is an important intermediate in the biological nitrogen cycle and is present in soils and surface water. Nitrite, formed during the biodegradation of nitrate and ammonical nitrogen or nitrogenous organic matter, is an important indicator of pollution of natural water. A simple, selective and sensitive spectrophotometric method for the determination of trace amount of nitrite in water is described. This method is based on diazo coupling reaction, where 4-aminophenylacetic acid is treated with nitrite under acidic condition to form diazonium ion which is subsequently coupled with oxine to form a stable orange coloured azo-dye. The formed azo-dye has absorption maxima at 480 nm. Various analytical parameters have been studied. The applicability of Beer-Lambert's law may be tested by measuring the absorbance of series of solutions of known concentration of absorbing species. The system obeys Lambert-Beer’s law over the range 0.2 to 1.8 µg/ml of nitrite. The correlation coefficient, molar absorptivity and Sandell’s sensitivity of the method were found to be 0.983, 1.077×104 litmol-1cm-1 and 4.27×10-3 µgcm-2 respectively. The percentage recovery was found to range from 93.98% - 108.9% indicating the suitability of the method for the determination of nitrite in water. The details results will be discussed in the conference.

Spectrophotometric determination of trace amount of nitrite in water with 4-aminophenylacetic acid and oxine

2019 Spring National Meeting

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