ABSTRACT
Many nitrate minerals occur in nature, such as potassium nitrate, KNO3 or saltpeter, and sodium nitrate, NaNO3 or Peru saltpeter. Nitrate salts have wide industrial applications. They are used as fertilizers in agriculture, and are also common laboratory chemicals. Nitrates are ubiquitously found in the environment at low concentrations. Most metal nitrates are soluble in water and occur in trace amounts in surface- and groundwater. Nitrate is toxic to human health and chronic exposure to high concentrations of nitrate may cause methemoglobinemia. The maximum contaminant limit in potable water imposed by the US Environmental Protection Agency (EPA) is 10 mg nitrate as nitrogen/L. Nitrates in water may be analyzed by the following methods: ion chromatography, nitrate selective electrode method, cadmium reduction method, miscellaneous reduction method and brucine method. The cadmium reduction method and the miscellaneous reduction method are colorimetric procedures based on the reduction of nitrate to nitrite, followed by diazotization and then coupling to an azo dye.
