Molecular sieve trap for nitrogen compound detection
First Claim
1. Apparatus for selectively trapping substances in a gas stream comprising a cartridge having an inlet at one end for receiving a gas stream, an outlet at the end opposite said inlet end, and a shell defining a chamber between said inlet and said outlet, said chamber containing a packing of a granular molecular sieve material permeable to the flow therethrough of NO gas and adapted to trap and hold substances therein which might otherwise interfere with measurement of the NO gas which has passed through said packing.
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Accused Products
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 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.
44 Citations
21 Claims
- 1. Apparatus for selectively trapping substances in a gas stream comprising a cartridge having an inlet at one end for receiving a gas stream, an outlet at the end opposite said inlet end, and a shell defining a chamber between said inlet and said outlet, said chamber containing a packing of a granular molecular sieve material permeable to the flow therethrough of NO gas and adapted to trap and hold substances therein which might otherwise interfere with measurement of the NO gas which has passed through said packing.
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8. Apparatus for measuring in a sample the amount of predetermined nitrogen compounds comprising:
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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. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. Apparatus for measuring in a gaseous sample the concentration of at least one oxide of nitrogen comprising:
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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 NO2 gases and effective to trap and hold substances whose presence in said reaction chamber might interefere with measurement of NO or NO2 gas in said sample. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification