US 4,066,411 AGranted

N-nitroso compound analyzer with sample atomization

AssigneeThermo Electron Corporation

InventorsDavid H. Fine, John J. Fronduto, David P. Rounbehler

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Abstract

A liquid-gas interface is provided between a heated reaction chamber of an N-nitroso compound detection system and a liquid chromatograph. The liquid-gas interface atomizes liquid chromatograph effluent, including the N-nitroso compounds to be measured, with a stream of carrier gas, into the reaction chamber. In the heated reaction chamber, the effluent from the interface is vaporized. Condensation of non-volatile N-nitroso compounds is avoided by preheating the liquid effluent prior to atomization.

Claims7

Dependent claims

Apparatus for measuring in a sample the amount of N-nitroso compounds having the general formula:

##STR3## wherein R.sub.1 and R.sub.2 are the same or different organic radicals, including those radicals which together with the non-nitroso N of the depicted N--NO bond constitute a nitrogen heterocyclic radical, and wherein the N--NO bond is the weakest bond in the molecule, comprising:
A. high performance chromatograph including a column, having an input end for receiving said sample in liquid solution form with a solvent and an output end for ejecting column effluent, wherein the ejection of the N-nitroso portion having N-nitroso compounds therein is separate in time from the ejection of other portions of said sample having other compounds therein and further wherein ejections of portions having different N-nitroso compounds are separate in time from each other;
B. chamber means for pyrolyzing said column effluent at a temperature in the range 300.degree. to 500.degree. C to liberate from said N-nitroso compounds nitric oxide (NO) in the gaseous phase;
C. liquid-gas interface means having an effluent delivery means extending into said chamber means for conveying and discharging liquid chromatograph effluent thereinto and carrier gas delivery means for directing carrier gas into said chamber means, said effluent delivery means and said carrier gas delivery means cooperating to atomize liquid effluent into said chamber means, both said delivery means cooperating to promote transfer of heat from said chamber means to said liquid effluent and said carrier gas prior to said atomization, said interface means and said chamber means cooperating to vaporize column effluent as a continuous process for preserving the timewise separation of N-nitroso compounds therein;
D. means for establishing a sub-atmospheric pressure in said chamber means for promoting vaporization of said column effluent;
E. means for measuring in the gaseous phase the amount of nitric oxide (NO) liberated in said chamber means;
and
F. a cold trap interposed between said chamber means and said measuring means for removing chromatograph solvent from the input to said measuring means, said cold trap including an input port for receiving a cold trap input gas from said chamber means and an output port for injecting gaseous cold trap effluent into said measuring means.

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Abstract

Apparatus for measuring in a sample the amount of N-nitroso compounds having the general formula:

##STR3## wherein R.sub.1 and R.sub.2 are the same or different organic radicals, including those radicals which together with the non-nitroso N of the depicted N--NO bond constitute a nitrogen heterocyclic radical, and wherein the N--NO bond is the weakest bond in the molecule, comprising:
A. high performance chromatograph including a column, having an input end for receiving said sample in liquid solution form with a solvent and an output end for ejecting column effluent, wherein the ejection of the N-nitroso portion having N-nitroso compounds therein is separate in time from the ejection of other portions of said sample having other compounds therein and further wherein ejections of portions having different N-nitroso compounds are separate in time from each other;
B. chamber means for pyrolyzing said column effluent at a temperature in the range 300.degree. to 500.degree. C to liberate from said N-nitroso compounds nitric oxide (NO) in the gaseous phase;
C. liquid-gas interface means having an effluent delivery means extending into said chamber means for conveying and discharging liquid chromatograph effluent thereinto and carrier gas delivery means for directing carrier gas into said chamber means, said effluent delivery means and said carrier gas delivery means cooperating to atomize liquid effluent into said chamber means, both said delivery means cooperating to promote transfer of heat from said chamber means to said liquid effluent and said carrier gas prior to said atomization, said interface means and said chamber means cooperating to vaporize column effluent as a continuous process for preserving the timewise separation of N-nitroso compounds therein;
D. means for establishing a sub-atmospheric pressure in said chamber means for promoting vaporization of said column effluent;
E. means for measuring in the gaseous phase the amount of nitric oxide (NO) liberated in said chamber means;
and
F. a cold trap interposed between said chamber means and said measuring means for removing chromatograph solvent from the input to said measuring means, said cold trap including an input port for receiving a cold trap input gas from said chamber means and an output port for injecting gaseous cold trap effluent into said measuring means.

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