A solid sorbent personal sampling method for the simultaneous collection of nitrogen dioxide and nitric oxide in air

A sampling method is described for the collection of air samples containing both nitrogen dioxide (NO2) and nitric oxide (NO) in the range of 0.5 to 5 ppm NO2 and 9 to 50 ppm NO. These two gases are trapped on a solid sorbent sampling tube which employs the collection of the NO2 on a triethanol-amine (TEA)-impregnated molecular sieve surface; the oxidation of NO to NO2 by a solid oxidizer; and the collection of the converted NO on another section of TEA sorbent. The trapped NO/NO2 on each TEA section is desorbed and the concentrations are determined spectrophotometrically. At all concentrations tested, the collection efficiency for NO2 averaged approximately 96%. The collection efficiencies for NO were as follows: at 9 ppm, 97%; at 11 ppm, 106%; at 24 ppm, 84%; and at 50 ppm, 67%.