Molecular sieve trap for nitrogen compound detection

Apparatus for measuring in a sample the amount of predetermined nitrogen compounds comprising:

• a chromatograph for receiving said sample and producing an effluent including, at separate intervals of time, a first portion containing said predetermined nitrogen compounds and a second portion without said compounds;
• a reactor for selectively liberating NO gas from the nitrogen compounds of said first portion, thereby producing a reactor effluent containing NO gas;
• a NO detector for measuring the amount of NO gas liberated in said reactor;
• and
• a trap between said reactor and said detector for selectively trapping substances from said reactor effluent, said trap including a packing of a granular molecular sieve material permeable to the flow therethrough of NO gas and effective to trap and hold substances whose presence in said detector might interfere with measurement of the NO gas liberated by said reactor.

Apparatus for measuring in a gaseous sample the concentration of at least one oxide of nitrogen comprising:

• a reaction chamber for permitting a chemiluminescent reaction therein of a selected constituent of the sample with a reagent;
• means for supplying said reagent and said gaseous sample to the reaction chamber;
• means for detecting the light produced in said chamber during a chemiluminescent reaction;
• and a trap for selectively removing substances from said gaseous sample prior to entry of said sample into said reaction chamber, said trap comprising a packing of a granular molecular sieve material permeable to the flow therethrough of NO and NO.sub.2 gases and effective to trap and hold substances whose presence in said reaction chamber might interefere with measurement of NO or NO.sub.2 gas in said sample.