US5141534A
Expired / Lapsed
US
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Sample collection and inlet systems for gas chromatography apparatus
Assignee: MICHIGAN A CONSTITUTIONAL CORP OF MICHIGAN, University of, Regents of
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Filing: 1991-06-18
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Granted: 1992-08-25
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Expires: 2011-06-18
Abstract
Abstract A gas chromatography system of the type incorporating a thermal focusing chamber for introducing a sample into a column for separation and analysis. The system of the present invention provides benefits in terms of reducing memory effect of one analysis being influenced by prior experiments, a reduction in system dead volume which leads to broadening of peaks produced on the chromatogram and artifacts caused by sample decomposition. These advantages are achieved principally through a novel fluid circuit in which the sample is trapped onto the column by trapping it at the end of the thermal focusing chamber closest to the column. This feature has the effect of eliminating the necessity of the sample residing in the heated focusing chamber for a period giving rise to sample decomposition. This system further avoids the necessity of passing the inlet flow through mechanical valves which also contributes to memory effect. This system further has the benefit of enabling sampling of sources at various pressures including ambient pressure as an air quality sensing probe. An alternative embodiment is a simplified system for enabling ambient pressure source monitoring without mechanical valves in the sample flow path.
Inventors
- 👤 Richard D. Sacks
- 👤 Mark A. Klemp
- 👤 Christine L. Rankin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:29
CPC Classifications
G; G01; G01N; G01N30/00; G01N30/02; G01N30/04; G01N30/06; G01N30/12; G01N30/26; G01N30/38; G01N30/40; G01N1/00; G01N1/28; G01N1/40; G01N2030/121; G01N2030/122; G01N2030/382; G01N2030/383; G01N2030/402; G01N2030/405
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
173 words
A gas chromatography system comprising: a source of a sample, a source of a carrier gas, a chromatography separation column, a sample tube having a first end communicating with said source of a carrier gas and having a second end communicating with said column and said source of a sample, temperature control means for controlling the temperature of said sample tube between a low temperature for condensing at least some components of said sample, and a high temperature for vaporizing said components, a controllable pressure means for causing said sample to flow into said sample tube second end, control means for controlling said temperature control means and said pressure means wherein during a collection mode, said pressure means draws said sample into said sample tube second end while said sample tube is at said low temperature, and during an injection mode, causes said sample tube to be heated to said high temperature and allowing said carrier gas to flow into said sample tube first end, through said sample tube, and into said column.
Claim 2
Dependent Claim
173 words
A gas chromatography system comprising: a source of a sample, a source of a carrier gas, a chromatography separation column, a sample tube having a first end communicating with said source of a carrier gas and having a second end communicating with said column and said source of a sample, temperature control means for controlling the temperature of said sample tube between a low temperature for condensing at least some components of said sample, and a high temperature for vaporizing said components, a controllable pressure means for causing said sample to flow into said sample tube second end, control means for controlling said temperature control means and said pressure means wherein during a collection mode, said pressure means draws said sample into said sample tube second end while said sample tube is at said low temperature, and during an injection mode, causes said sample tube to be heated to said high temperature and allowing said carrier gas to flow into said sample tube first end, through said sample tube, and into said column.
Claim 3
Dependent Claim
24 words
A gas chromatography system according to claim 1 wherein said controllable pressure means comprises a vacuum source communicating with said sample tube first end.
Claim 4
Dependent Claim
104 words
A gas chromatography system according to claim 2 further comprising a first conduit branch communicating said source of carrier gas with said sample tube first end, and a second conduit branch communicating said source of a sample with said sample tube second end, with first valve means between said first and second branches for allowing fluid flow between said branches, wherein during said collection mode, said first valve means is closed causing said carrier gas to flow through said first branch and to said vacuum source, and said sample to flow through said second branch and through said sample tube toward said vacuum source.
Claim 5
Dependent Claim
38 words
A gas chromatography system according to claim 3 wherein during said injection mode, said first valve means is opened allowing said carrier gas to flow through at least a portion of said second branch thereby flushing said portion.
Claim 6
Dependent Claim
49 words
A gas chromatography system according to claim 3 wherein said control means further controls said gas chromatography system to provide a backflush mode in which said source of vacuum is actuated and said first valve means is opened allowing said column and said second conduit branch to be purged.
Claim 7
Dependent Claim
59 words
A gas chromatography system according to claim 3 further comprising a first fluid restrictor means in said second branch between said first valve means and said sample source and a second fluid restrictor means in said second branch between said first valve means and said column, wherein said restrictors control the flow of fluids during said modes of operation.
Claim 8
Dependent Claim
40 words
A gas chromatography system according to claim 3 further comprising a third fluid restrictor means in said first conduit branch between said first valve means and said sample tube for controlling the flow of fluids during said modes of operation.
Claim 9
Dependent Claim
21 words
A gas chromatography system according to claim 3 wherein said vacuum source comprises a vacuum pump and a second valve means.
Claim 10
Dependent Claim
121 words
A gas chromatography system comprising: a source of a sample, a source of a carrier gas, a chromatography separation column, a sample tube, temperature control means for controlling the temperature of said sample tube between a low temperature for condensing at least some components of said sample, and a high temperature for vaporizing said components, and fluid circuit and control means for causing said sample to flow into said sample tube in a first direction of flow during a collection mode during which said sample tube is at said low temperature and causing said carrier gas to flow through said sample tube in an opposite second direction during an injection mode, during which said sample tube is at said high temperature.
Claim 11
Dependent Claim
121 words
A gas chromatography system comprising: a source of a sample, a source of a carrier gas, a chromatography separation column, a sample tube, temperature control means for controlling the temperature of said sample tube between a low temperature for condensing at least some components of said sample, and a high temperature for vaporizing said components, and fluid circuit and control means for causing said sample to flow into said sample tube in a first direction of flow during a collection mode during which said sample tube is at said low temperature and causing said carrier gas to flow through said sample tube in an opposite second direction during an injection mode, during which said sample tube is at said high temperature.
Claim 12
Dependent Claim
40 words
A gas chromatography system according to claim 9 wherein said fluid circuit and control means comprises said sample tube having a first end communicating with said source of a carrier gas and having a second end communicating with said column.
Claim 13
Dependent Claim
33 words
A gas chromatography system according to claim 10 further comprising a controllable pressure means for causing said sample to flow into said tube second end in said first direction during said collection mode.
Claim 14
Dependent Claim
24 words
A gas chromatography system according to claim 11 wherein said controllable pressure means comprises a vacuum source communicating with said sample tube first end.
Claim 15
Dependent Claim
108 words
A gas chromatography system according to claim 12 further comprising a first conduit branch communicating said source of carrier gas with said sample tube first end, and a second conduit branch communicating said source of a sample to said sample tube second end, with first valve means between said first and second branches for allowing fluid flow between said branches, wherein during said collection mode, said first valve means is closed causing said carrier gas to flow through said first branch and toward said vacuum source, and said sample to flow through said second branch and through said sample tube in said first direction toward said vacuum source.
Claim 16
Dependent Claim
38 words
A gas chromatography system according to claim 13 wherein during said injection mode, said first valve means is opened allowing said carrier gas to flow through at least a portion of said second branch thereby flushing said portion.
Claim 17
Dependent Claim
58 words
Gas chromatography system according to claim 13 further comprising a first fluid restrictor means in said second branch between said first valve means and said sample source and a second fluid restrictor means in said second branch between said first valve means and said column, wherein said restrictors control the flow of fluids during said modes of operation.
Claim 18
Dependent Claim
39 words
A gas chromatography system according to claim 13 further comprising a third restrictor means in said first conduit branch between said first valve means and said sample tube, for controlling the flow of fluids during said modes of operation.
Claim 19
Dependent Claim
49 words
A gas chromatography system according to claim 12 wherein said control means further controls said gas chromatography system to provide a backflush mode in which said source of vacuum is actuated and said first valve means is opened allowing said column and said second conduit branch to be purged.
Claim 20
Dependent Claim
21 words
A gas chromatography system according to claim 12 wherein said vacuum source comprises a vacuum pump and a second valve means.
Claim 21
Dependent Claim
183 words
A gas chromatography system comprising: a source of a sample, a source of a carrier gas a chromatography separation column, a sample tube in fluid communication with said column having an inlet end and an outlet end, a temperature control means for controlling the temperature of said sample tube between a low temperature for condensing at least some components of said sample, and a high temperature for vaporizing said components, a controllable source of vacuum communicating between said sample tube and said column, first restrictor means communicating with said carrier gas source and to said sample tube first end, second restrictor means communicating said sample source with said sample tube first end, and control means for providing a collection mode energizing said vacuum source for drawing said carrier gas and said sample source through said restrictors into said sample tube while said sample tube is at said low temperature, and in an injection mode deactivating said vacuum source causing said carrier gas to purge said second restrictor and injecting said sample into said column as said sample tube is at said high temperature.
Claim 22
Dependent Claim
183 words
A gas chromatography system comprising: a source of a sample, a source of a carrier gas a chromatography separation column, a sample tube in fluid communication with said column having an inlet end and an outlet end, a temperature control means for controlling the temperature of said sample tube between a low temperature for condensing at least some components of said sample, and a high temperature for vaporizing said components, a controllable source of vacuum communicating between said sample tube and said column, first restrictor means communicating with said carrier gas source and to said sample tube first end, second restrictor means communicating said sample source with said sample tube first end, and control means for providing a collection mode energizing said vacuum source for drawing said carrier gas and said sample source through said restrictors into said sample tube while said sample tube is at said low temperature, and in an injection mode deactivating said vacuum source causing said carrier gas to purge said second restrictor and injecting said sample into said column as said sample tube is at said high temperature.
Claim 23
Dependent Claim
15 words
A gas chromatography system according to claim 19 wherein said sample source comprises ambient air.
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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) | 1995-08-25 | 1996-02-24 | 1996-08-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-08-25 | 2000-02-24 | 2000-08-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-08-25 | 2004-02-24 | 2004-08-25 | $7700.00 | Window Closed / Lapsed |