Nitric oxide plus nitrogen dioxide

In this metho d [ 124 ] nitrate, nitrate plus nitrite or nitrite alone are selectively reduced to nitric oxide, which is swept from the sample in a helium carrier gas flow. Nitric oxide is allowed to react with ozone in a nitrogen oxide analyser, where it forms nitrogen dioxide. The return of the nitrogen dioxide to the ground state is accompanied by release of a photon, which is detected by a photomultiplier. The integrated output of the photomultiplier over the time that the nitric oxide is pinged from the sample is proportional to the nitrite content of the sample. 

Tetraphenylhydrazine is a while solid, soluble in chloroform, acetone, benzene, or toluene, and upon standing is changed into triphenylaminc plus azobenzene. In solution, tetraphenylhydrazine dissociates into nitrogen diphenyl. (Ct,Hs) N-. free radical, which in toluene at 90cC reads with nitric oxide, NO, Tetraphenylhydrazine is formed by oxidation of diphenylamine,. by lead dioxide. 

The problem of identifying and measuring ozone in the complex gaseous-aerosol mixture which is smog is formidable. There are such gases present as nitric oxide, nitrogen dioxide, sulfur dioxide, hydrocarbon vapors from methane up to probably xylene, plus such partial oxidation products as aldehydes, ketones, and acids. The search for a method of high specificity has been an intensive one. 

USE In large quanities in the manuf of nitric acid, also in the bleaching of rayon, as stabilizer (to prevent free-radical decompn) for propylene, methyl ether, etc. Caution Immediately on contact with air, nitric oxide is converted to the highly poisonous nitrogen dioxide nitrogen tetroxide, or both. Gas masks plus adequate ventilation are mandatory when handling even small amounts in the laboratory- See also Nitrogen Dioxide,... 

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