Kinetic Evaluation of the Factor Used in the Saltzman Analysis of Oxides of Nitrogen

The Saltzman reaction, a modification of the Griess-Ilsovay diazotization-coupling, is commonly used for analysis of oxides of nitrogen at air pollution levels. A factor is generally applied to the results to compensate for partial conversion to non-reactive nitrogen (V). A modification of the method used at the Bureau of Mines for the higher levels of oxides of nitrogen found in diesel exhaust yields quantitative results. An explanation for this is offered, based on rate studies of the gas-phase oxidation of nitric oxide to nitrogen dioxide.