Abstract: A molecular sieve trap is disclosed for selective trapping of substances in a gas stream, the trap being particularly useful in systems for detecting nitrogen compounds such as N-nitrosamines or nitrogen oxides in a sample. The trap comprises a cartridge containing a packing of a granular adsorbent molecular sieve material with a carefully controlled pore size of about ten angstroms and a preference for adsorbing polar substances. The packing readily passes NO and NO.sub.2 gases in a gas stream directed through the trap while trapping and retaining larger and/or more polar molecules such as those of double-bonded carbon compounds and sulfur compounds which could otherwise interfere with subsequent measurement of the NO or NO.sub.x content of the gas stream. An N-nitroso compound detection system incorporating the molecular sieve trap is described wherein the molecular sieve trap is interposed between a pyrolyzer and a chemiluminescent NO detector to selectively trap substances in the reactor effluent.

Abstract: A method and apparatus are disclosed for extracting N-nitroso compounds from air samples without artifact formation of nitrosamines from precursors in the sample. The apparatus includes a cartridge having two zones between a first port and a second port. The first zone, closest to the first port, contains an air pervious packing of a granular, solid phase amine complexing agent. The second zone, closest to the second port, contains an air pervious packing of a mixture of a granular, solid phase amine complexing agent and a particulate sorbent adapted to extract and concentrate N-nitroso compounds from air. The method includes a first step of driving an air sample through the first and second contiguous zones of the cartridge in succession, and a second step of driving an eluent through the second and first zones in succession, or backflushing the cartridge.