Patent US5092155A successfully refreshed from Google Patents.
US5092155A
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High speed detection of vapors of specific compounds
Assignee: Thermo Fisher Scientific Inc
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Filing: 1987-07-08
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Granted: 1992-03-03
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Expires: 2007-07-08
Abstract
Abstract A highly selective, sensitive, fast detection system and method are disclosed for detecting vapors of specific compounds in air. Vapors emanating from compounds such as explosives, or stripped from surfaces using heat and suction from a hand-held sample gun, are collected on surfaces coated with gas chromatograph (GC) material which trap explosives vapors but repel nitric oxide, then are desorbed and concentrated in one or more cold spot concentrators. A high speed gas chromatograph (GC) separates the vapors, after which specific vapors are decomposed in two pyrolyzers arranged in parallel and the resulting nitric oxide is detected. A low temperature pyrolyzer with silver produces NO from nitramines or nitrite esters; a high temperature pyrolyzer decomposes all explosives vapors to permit detection of the remaining explosives. Also disclosed is a series arrangement of pyrolyzers and gas chromatographs and an NO detector to time-shift detection of certain vapors and facilitate very fast GC analyses. The use of hydrogen as a carrier gas, plus unique collectors and concentrators, high speed heaters, NO detectors, and very fast, temperature-programmable GC's enhance selectivity, sensitivity and speed of detection.
Inventors
- 👤 David P. Rounbehler
- 👤 Eugenie Hainsworth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:46
CPC Classifications
G; G01; G01N; G01N30/00; G01N30/02; G01N30/26; G01N30/38; G01N30/46; G01N30/461; G01N1/00; G01N1/02; G01N30/04; G01N30/06; G01N30/08; G01N30/12; G01N30/84; G01N33/00; G01N33/0004; G01N33/0009; G01N33/0027; G01N33/0036; G01N33/0057; G01V; G01V9/00; G01V9/007; G01N1/22; G01N1/2202; G01N1/2214; G01N1/2226; G01N1/28; G01N1/40; G01N2001/022; G01N2001/028; G01N2030/022; G01N2030/025; G01N2030/065; G01N2030/085; G01N2030/121; G01N2030/122; G01N2030/123; G01N2030/125; G01N2030/126; G01N30/14; G01N2030/143; G01N30/16; G01N2030/167; G01N30/28; G01N30/30; G01N2030/3007; G01N2030/3046; G01N2030/3053; G01N2030/3061; G01N2030/3069; G01N2030/3076; G01N2030/3084; G01N30/62; G01N2030/626; G01N30/64; G01N2030/642; G01N2030/8405; G01N21/00; G01N21/75; G01N21/76; G01N30/40; G01N30/72
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
236 words
Apparatus for detecting vapors of specific nitrogen-containing compounds comprising; means for forming a gas sample containing vapors of said sepcific compounds and a non-oxidizing carrier gas; a first gas chromatograph for effecting timewise separation of the vapors of said gas samples; means for directing said gas sample through said first gas chromatograph; an NO detector operable to detect nitric oxide and to a low temperature pyrolyzer, a second gas chromatograph, and a high temperature pyrolyzer connected in series between said first gas chromatograph and said NO detector; said low temperature pyrolyzer operable to produce nitrogen dioxide or nitric oxide by decomposing vapors of a first set of compounds, if present in said gas sample received from said first gas chromatograph without producing nitric oxide from other substances in said gas sample; said second gas chromatograph operable to allow very rapid passage therethrough of the nitrogen dioxide and nitric oxide produced in said low temperature pyrolyzer while retarding passage of vapors of a second set of compounds and other substances in said gas sample to effect additional timewise separation of said sample; said high temperature pyrolyzer operable to produce nitric oxide by decomposing nitrogen dioxide and vapors of said second set of compounds present in the gas sample received from said second gas chromatograph; and means for detecting, based on signals produced by said NO detector, the vapors of said specific compounds present in said gas sample.
Claim 2
Dependent Claim
236 words
Apparatus for detecting vapors of specific nitrogen-containing compounds comprising; means for forming a gas sample containing vapors of said sepcific compounds and a non-oxidizing carrier gas; a first gas chromatograph for effecting timewise separation of the vapors of said gas samples; means for directing said gas sample through said first gas chromatograph; an NO detector operable to detect nitric oxide and to a low temperature pyrolyzer, a second gas chromatograph, and a high temperature pyrolyzer connected in series between said first gas chromatograph and said NO detector; said low temperature pyrolyzer operable to produce nitrogen dioxide or nitric oxide by decomposing vapors of a first set of compounds, if present in said gas sample received from said first gas chromatograph without producing nitric oxide from other substances in said gas sample; said second gas chromatograph operable to allow very rapid passage therethrough of the nitrogen dioxide and nitric oxide produced in said low temperature pyrolyzer while retarding passage of vapors of a second set of compounds and other substances in said gas sample to effect additional timewise separation of said sample; said high temperature pyrolyzer operable to produce nitric oxide by decomposing nitrogen dioxide and vapors of said second set of compounds present in the gas sample received from said second gas chromatograph; and means for detecting, based on signals produced by said NO detector, the vapors of said specific compounds present in said gas sample.
Claim 3
Dependent Claim
15 words
Apparatus as in claim 1 including a supply of hydrogen as said non-oxidizing carrier gas.
Claim 4
Dependent Claim
30 words
Apparatus as in claim 1 wherein said low temperature pyrolyzer contains a silver surface and is operable at a temperature in the range of about 160° C. to 250° C.
Claim 5
Dependent Claim
62 words
Apparatus as in claim 1 wherein said means for forming a gas sample includes means for trapping vapors of said specific compounds from an air sample and means for concentrating said vapors such that said gas sample received by the first gas chromatograph has a concentration of vapors at least 100 times greater than the concentration of vapors in said air sample.
Claim 6
Dependent Claim
24 words
Apparatus as in claim 1 wherein said low temperature pyrolyzer is operable to decompose vapors of nitramines and nitrite esters to produce nitrogen dioxide.
Claim 7
Dependent Claim
19 words
Apparatus as in claim 1 wherein said high temperature pyrolyzer is operable to decompose vapors of essentially all explosives.
Claim 8
Dependent Claim
28 words
Apparatus as in claim 1 wherein said high temperature pyrolyzer is a ceramic pyrolyzer operable at a temperature in the range of about 700° C. to 1000° C.
Claim 9
Dependent Claim
26 words
Apparatus as in claim 1 including means for rapidly heating said first and second gas chromatographs over selected time intervals to remove vapors from said chromatographs.
Claim 10
Dependent Claim
31 words
Apparatus as in claim 1 wherein said means for concentrating said vapors of said specific compounds includes a tube containing a coating of polymerized methyl silicone of thickness about 0.1-5 microns.
Claim 11
Dependent Claim
25 words
Apparatus as in claim 9 including means for flash-heating said tube to rapidly desorb said vapors of said specific compounds into said first gas chromatograph.
Claim 12
Independent Claim
204 words
A method of detecting vapors of specific nitrogen-containing compounds comprising: forming a gas sample containing of said specific compounds and a non-oxidizing carrier gas; directing said gas sample through a first gas chromatograph to timewise separate vapors of various compounds from other substnces and from one another; in a low temperature pyrolyzer operable to receive the output of said first gas chromatograph, decomposing vapors of a first set of compounds to produce nitric oxide or nitrogen dioxide without producing nitric oxide or nitrogen dioxide from other substances in said gas sample; directing the output of said low temperature pyrolyzer through a second gas chromatograph to allow very rapid passage therethrough of nitric oxide and nitrogen dioxide, while retarding passage of a second set of compounds and other substances in said gas sample to effect additional timewise separation of said sample; in a high temperature pyrolyzer operable to receive the output of said second gas chromatograph, decomposing vapors of said second set of compounds and nitrogen dioxide present in said gas sample received from said second gas chromatograph to produce nitric oxide; detecting the nitric oxide produced in said pyrolyzers; and determining, from said nitric oxide detected, the specific compounds present in said gas sample.
Claim 13
Independent Claim
204 words
A method of detecting vapors of specific nitrogen-containing compounds comprising: forming a gas sample containing of said specific compounds and a non-oxidizing carrier gas; directing said gas sample through a first gas chromatograph to timewise separate vapors of various compounds from other substnces and from one another; in a low temperature pyrolyzer operable to receive the output of said first gas chromatograph, decomposing vapors of a first set of compounds to produce nitric oxide or nitrogen dioxide without producing nitric oxide or nitrogen dioxide from other substances in said gas sample; directing the output of said low temperature pyrolyzer through a second gas chromatograph to allow very rapid passage therethrough of nitric oxide and nitrogen dioxide, while retarding passage of a second set of compounds and other substances in said gas sample to effect additional timewise separation of said sample; in a high temperature pyrolyzer operable to receive the output of said second gas chromatograph, decomposing vapors of said second set of compounds and nitrogen dioxide present in said gas sample received from said second gas chromatograph to produce nitric oxide; detecting the nitric oxide produced in said pyrolyzers; and determining, from said nitric oxide detected, the specific compounds present in said gas sample.
Claim 14
Dependent Claim
37 words
A method as in claim 11 including, prior to directing said gas sample through said first gas chromatograph, trapping said vapors of said specific compounds from an air sample and concentrating said vapors in said carrier gas.
Claim 15
Dependent Claim
12 words
A method as in claim 11 wherein said carrier gas is hydrogen.
Claim 16
Dependent Claim
33 words
A method as in claim 11 wherein said vapors of said first set of compounds are decomposed in the presence of silver and at a temperature in the range of about 160°-250° C.
Claim 17
Dependent Claim
37 words
A method as in claim 11 including, prior to said detection of nitric oxide, directing the output of said high temperature pyrolyzer through a trap effective to trap compounds having relatively large molecules while passing nitric oxide.
Claim 18
Dependent Claim
17 words
A method as in claim 11 wherein said first set of compounds are nitramines and nitrite esters.
Claim 19
Dependent Claim
12 words
A method as in claim 11 wherein said specific compounds are explosives.
Claim 20
Dependent Claim
57 words
A method as in claim 11 wherein said steps of directing the gas sample through said gas chromatographs include rapidly heating the analytical columns of said gas chromatographs for selected times and wherein all of the steps of said method subsequent to said gas sample formation are performed in a total of less that about five seconds.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-03 | 1995-09-02 | 1996-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-03 | 1999-09-02 | 2000-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-03 | 2003-09-02 | 2004-03-03 | $7700.00 | Window Closed / Lapsed |