Development of a Method for the Analysis of NO2and NH3by NO-Measuring Instruments

Abstract

Adaptation of available instruments to the analysis of NO₂ and NH₃ became important with the introduction of the Federal Constant Volume Sampling procedure for exhaust analysis in 1970. Two instruments, the NO optical detector (NOOD) and the non-dispersive infrared analyzer (ND1R), are both fast and accurate. The use of a system of two converters in conjunction with either of these instruments permits the analysis of a gas stream for NO, NO₂, and NH₃. NO is measured on the gas stream before conversion; NO₂ is determined after the gas stream has passed over a C-Mo converter at 475°C; and NH₃ is determined after the gas has been conducted over a C-Cu converter.