Molecular sieve trap for nitrogen compound detection

摘要

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 NO2 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 NOx 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. Also disclosed is a NOx detection system having a molecular sieve trap in a sample inlet line of a NOx detector.