Detecting Hydrazine via Optical Detection of Ammonia

In a proposed method for rapidly detecting hydrazine in air at concentrations at or above 10 parts per billion by volume (ppbv), tunable diode lasers (TDLs) and photodetectors would be used to measure infrared absorption spectra of both ammonia and hydrazine simultaneously. In this method, one would take advantage of the fact that (1) ammonia is formed in the decomposition of hydrazine and is always present when hydrazine is present and (2) the spectral features attributable to ammonia are much stronger than those attributable to hydrazine, and thus ammonia can be detected more easily. In a typical situation in which hydrazine is suspected of leaking and in which one could rule out an alternative source of ammonia (e.g., an open bottle of household ammonia solution or window cleaner), an ammonia spectrum could thus be taken as an indication of hydrazine.