Nitrates are particularly harmful to human health because of the reduction tonitrite which takes place in humans. Long term effects arise from reaction of nitrites with certain substrates such asamines, amides, and amino acids to produce N-nitroso compounds, which have beenfound in numerous animal studies to be carcinogenic. Due to this factor, nitrate andnitrite are regulated by the US Environmental Protection Agency (USEPA) (maximum allowable levels are 10ppm and 1ppm,respectively) due to their common occurrence as constituents in drinking water. Theanalysis of these compounds is a routine analytical procedure in most water laboratories.The standard method for the determination of nitrate in drinking water, USEPA Method353.2 "Determination of Nitrate-Nitrite by Automated Colorimetry," employs cadmiumas the reductant for the conversion of nitrate to nitrite. The nitrite is then analyzedcolorimetrically by way of the Griess reaction. This procedure is not only tedious, but thebyproducts of the cadmium column are hazardous to the environment. Once cadmium isintroduced to the soil, plants uptake the cadmium, and then, via the food chain, theexposure is passed upward towards humans. The objective is to find an alternative by useof Superior Stock Nitrate Reductase or YNaR1 (The Nitrate Elimination Co. of LakeLinden, Michigan). This enzyme, a natural reductant, combined with NADH, can replacethe cadmium column reduction, thus eliminating the need to dispose of toxic cadmiumwaste. Includes 3 references, table, figures.
