Water quality - Determination of nitrite - Manual cadmium reduction method

This technical specification outlines a standardized methodology for the determination of nitrite levels in water samples using the manual cadmium reduction method. The procedure involves reducing nitrite ions to nitric oxide through passage over a column of granulated cadmium, followed by the reaction of nitric oxide with sulfanilamide and N-(1-naphthyl)ethylenediamine to form an azo dye. The intensity of the resulting color, measured spectrophotometrically, is directly proportional to the nitrite concentration in the original sample. This approach is designed to ensure consistency and accuracy in analytical laboratories assessing water quality parameters across different environments. The method provides clear guidelines for reagent preparation, calibration, sample handling, and calculation of results. It serves as a reference for laboratories conducting routine analysis to monitor environmental water safety and compliance with relevant quality criteria. The protocol emphasizes precise control over experimental conditions to minimize interference and variability, supporting reliable data generation for regulatory and scientific purposes.