US5142143A
Expired / Lapsed
US
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Method and apparatus for preconcentration for analysis purposes of trace constitutes in gases
Assignee: Extrel CMS LLC
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Filing: 1991-10-30
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Granted: 1992-08-25
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Expires: 2011-10-30
Abstract
Abstract A preconcentrator for analyzing trace constituents in gases wherein a sample gas is introduced to a confined sorbent which thereafter is evacuated by a vacuum pump and a low-pressure carrier gas passes through the sorbent while it is desorbing, wherein the desorbed trace constituents are carried by the carrier gas to a detector that operates at low pressure such as a mass spectrometer. Because the mass of the carrier gas which carries the desorbed trace consituents to the detector is at a lower pressure and therefore has less density than the sample gas, the relative mass of trace constituents in the carrier gas is much greater than in the sample gas. The sample gas can be hot to assist desorption or a gas which reacts with trace constituents of interest to improve their detection. Valves located in the system between the sample gas intake, the carrier gas supply, the vacuum pump for the system and the detector operate to admit the sample gas, isolate the system, create a vacuum in the system, establish the sample gas flow, and to carry the trace consituents to the detector. Preconcentrators can be placed in parallel, whereby when one is desorbing and analyzing trace elements, the other is receiving the sample gas.
Inventors
- 👤 Wade L. Fite
- 👤 Stephen M. Penn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:18
CPC Classifications
G; G01; G01N; G01N1/00; G01N1/28; G01N1/40; G01N1/405; G01M; G01M3/00; G01M3/02; G01M3/04; G01M3/20; G01M3/202; G01N33/00; G01N33/0004; G01N33/0009; G01N33/0027; G01N33/0036; G01N33/0047; G01N33/0049; Y; Y10; Y10T; Y10T436/00; Y10T436/24; Y10T436/25; Y10T436/25375; Y10T436/255
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
160 words
A method of preconcentrating trace constituents in a gas for subsequent analysis which comprises the steps of: A adsorbing at least one of the trace constituents onto a confined sorbent material for a predetermined period of time from a sample gas moving at a predetermined gaseous mass flow rate; B confining said sorbent material in a sealed space which includes an inlet of a detector means for receiving said one trace constituent; and C desorbing said one trace element from said sorbent material for a predetermined period of time into a carrier gas moving at a predetermined gaseous mass flow rate which is substantially less than the gaseous mass flow rate of said sample gas whereby the desorbed amount of said one trace constituent relative to said carrier gas that contains said desorbed trace constituent is substantially greater than the same amount of said one trace constituent relative to the portion of said sample gas that contained said trace constituent.
Claim 2
Independent Claim
160 words
A method of preconcentrating trace constituents in a gas for subsequent analysis which comprises the steps of: A adsorbing at least one of the trace constituents onto a confined sorbent material for a predetermined period of time from a sample gas moving at a predetermined gaseous mass flow rate; B confining said sorbent material in a sealed space which includes an inlet of a detector means for receiving said one trace constituent; and C desorbing said one trace element from said sorbent material for a predetermined period of time into a carrier gas moving at a predetermined gaseous mass flow rate which is substantially less than the gaseous mass flow rate of said sample gas whereby the desorbed amount of said one trace constituent relative to said carrier gas that contains said desorbed trace constituent is substantially greater than the same amount of said one trace constituent relative to the portion of said sample gas that contained said trace constituent.
Claim 3
Dependent Claim
25 words
A method in accordance with claim 1, wherein said carrier gas containing said one trace constituent is introduced into said detector means through said inlet.
Claim 4
Dependent Claim
15 words
A method in accordance with claim 2, wherein said detector means comprises a mass spectrometer.
Claim 5
Dependent Claim
24 words
A method in accordance with claim 1, wherein the pressure of said carrier gas is substantially less than the pressure of said sample gas.
Claim 6
Dependent Claim
19 words
A method in accordance with claim 4, wherein said sample gas is substantially at or near ambient atmospheric pressure.
Claim 7
Dependent Claim
13 words
A method in accordance with claim 1, wherein said sample gas is air.
Claim 8
Dependent Claim
26 words
A method in accordance with claim 1, wherein said sorbent material is composed of particles of a solid material which are confined within a glass tube.
Claim 9
Dependent Claim
25 words
A method in accordance with claim 1, wherein said one trace constituent is caused to desorb from said sorbent material by heating said sorbent material.
Claim 10
Dependent Claim
27 words
A method in accordance with claim 8, wherein said carrier gas is preheated to assist in the desorption of said one trace constituent from said sorbent material.
Claim 11
Dependent Claim
13 words
A method in accordance with claim 1, wherein said carrier gas is air.
Claim 12
Dependent Claim
20 words
A method in accordance with claim 1, wherein said carrier gas does not chemically react with said one trace constituent.
Claim 13
Dependent Claim
35 words
A method in accordance with claim 1, wherein said carrier gas chemically reacts with said one trace constituent to produce a derivative of said one trace constituent that facilitates its detection by said detector means.
Claim 14
Dependent Claim
54 words
A method in accordance with claim 1, wherein a plurality of confined sorbent materials are provided in parallel with sealing means for each whereby one or more of said plurality of adsorbent materials may be used selectively to receive said sample gas and to desorb said carrier gas for analysis by said detector means.
Claim 15
Dependent Claim
22 words
A method in accordance with claim 3, wherein said mass spectrometer includes an electron-impact ionization ion source operatively connected to said inlet.
Claim 16
Dependent Claim
22 words
A method in accordance with claim 3, wherein said mass spectrometer includes a chemical ionization ion source operatively connected to said inlet.
Claim 17
Dependent Claim
18 words
A method in accordance with claim 15, wherein said carrier gas is a reagent gas for chemical ionization.
Claim 18
Dependent Claim
31 words
A method in accordance with claim 3, wherein said mass spectrometer includes a gas discharge ion source operatively connected to said inlet to operate at a pressure less than atmospheric pressure.
Claim 19
Dependent Claim
47 words
A method in accordance with claim 17, wherein a portion of said carrier gas entering said gas discharge ion source is removed therefrom by a vacuum pump and the remainder of said carrier gas is drawn through an aperture into the high vacuum of said mass spectrometer.
Claim 20
Independent Claim
197 words
An apparatus for preconcentrating trace constituents in a gas to facilitate their analysis which comprises: a sorbent material which is retained in a confined space and associated with means for selectively causing said sorbent material to adsorb or desorb said trace constituents; a sample gas source and valve for introducing said sample gas onto said sorbent material and means for selectively opening and closing said valve; a source of carrier gas connected to provide said carrier gas to said sorbent material; pumping means for selectively lowering the pressure in said confined space containing said sorbent material; a detector for detecting said trace constituents in said carrier gas; a confined passageway from said carrier gas source to said detector through said sorbent material, whereby when said sorbent material desorbs said trace constituents received from said sample gas they can be carried by said carrier gas to said detector at a pressure substantially less than the pressure of said sample gas, whereby the ratio of the density of said trace constituents to mass of said carrier gas is substantially increased relative to the ratio of the density of said trace constituents for a comparable mass of said sample gas.
Claim 21
Independent Claim
197 words
An apparatus for preconcentrating trace constituents in a gas to facilitate their analysis which comprises: a sorbent material which is retained in a confined space and associated with means for selectively causing said sorbent material to adsorb or desorb said trace constituents; a sample gas source and valve for introducing said sample gas onto said sorbent material and means for selectively opening and closing said valve; a source of carrier gas connected to provide said carrier gas to said sorbent material; pumping means for selectively lowering the pressure in said confined space containing said sorbent material; a detector for detecting said trace constituents in said carrier gas; a confined passageway from said carrier gas source to said detector through said sorbent material, whereby when said sorbent material desorbs said trace constituents received from said sample gas they can be carried by said carrier gas to said detector at a pressure substantially less than the pressure of said sample gas, whereby the ratio of the density of said trace constituents to mass of said carrier gas is substantially increased relative to the ratio of the density of said trace constituents for a comparable mass of said sample gas.
Claim 22
Dependent Claim
14 words
An apparatus in accordance with claim 19, wherein said detector comprises a mass spectrometer.
Claim 23
Dependent Claim
17 words
An apparatus in accordance with claim 20, wherein said mass spectrometer includes an electron-impact ionization ion source.
Claim 24
Dependent Claim
17 words
An apparatus in accordance with claim 20, wherein said mass spectrometer includes a chemical ionization ion source.
Claim 25
Dependent Claim
21 words
An apparatus in accordance with claim 22, wherein said carrier gas is a reagent gas to react with said trace constituents.
Claim 26
Dependent Claim
26 words
An apparatus in accordance with claim 20, wherein said mass spectrometer includes a gas discharge ion source that operates at a pressure less than atmospheric pressure.
Claim 27
Dependent Claim
44 words
An apparatus in accordance with claim 24, wherein a portion of said carrier gas entering said gas discharge ion source is removed therefrom by a vacuum pump and the remainder is removed through an aperture leading to a high vacuum in said mass spectrometer.
References Cited (Backward Citations)
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 |