Microdetermination of nitrates and nitrites in saliva, blood, water, and suspended particulates in air by gas chromatography.

A generally applicable method for the analysis of nitrates and nitrites has been used for a wide variety of samples, including human saliva, blood, drinking water, and airborne particulates. Aqueous nitrate ion is first converted to nitrobenzene by reaction with benzene (or another aromatic reactant) in the presence of a catalyst. The nitrobenzene is then quantitated by electron capture gas chromatography (GC-ECD). Nitrite ion and gaseous oxides of nitrogen can be determined also if such samples are treated appropriately prior to CG-ECD analysis. Other reactants such as 1,3,5-trimethoxybenzene can also be used in the place of benzene. The high sensitivity of ECD allows the quantitation of as little as 0.1 ppm (w/w) nitrate in a single drop of saliva or blood.