US4512181A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pressure compensation for a chromatograph
Assignee: Applied Automation Inc
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Filing: 1983-02-17
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Granted: 1985-04-23
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Expires: 2003-02-17
Abstract
Abstract In a chromatographic analysis, errors in the chromatographic analysis caused by barometric pressure variations are corrected by dividing the actual measured analysis (Cm) by a correction factor which is calculated based on the actual atmospheric pressure at the time the measurement is made (Pa), the atmospheric pressure at which the chromatographic analyzer system was calibrated, and the slope of a plot of Cm/Ca as a function of Pa/Pc where Ca is the magnitude that Cm would have if errors were not introduced by changes in barometric pressure.
Inventors
- 👤 Buell O. Ayers
- 👤 Edwin K. Clardy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:03
CPC Classifications
G; G01; G01N; G01N30/00; G01N30/02; G01N30/26; G01N30/28; G01N30/32; G01N30/62; G01N2030/626
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
216 words
In a chromatographic analyzer system for analyzing the composition of a sample, wherein said chromatographic analyzer system has a detector means for providing an output signal (C m ) having an amplitude which varies as a function of time in accordance with the sample composition and wherein said chromatographic analyzer system is calibrated at a barometric pressure P c , the improvement comprising apparatus for compensating for errors in said output signal, said errors being produced by changes in barometric pressure from the barometric pressure P c , said apparatus comprising: means for establishing a first signal representative of the actual barometric pressure (P a ) at the time an analysis is made using said chromatographic analyzer system; means for determining the slope (M) of a plot of C m divided by the magnitude that C m would have if errors were not introduced by changes in barometric pressure (C a ) as a function of P a /P c for said detector means and for said sample; means for calculating a pressure compensation factor using P c , P a and M; and means for dividing said output signal by said pressure compensation factor to compensate for errors in said output signal produced by changes in barometric pressure from the barometric pressure P c .
Claim 2
Dependent Claim
216 words
In a chromatographic analyzer system for analyzing the composition of a sample, wherein said chromatographic analyzer system has a detector means for providing an output signal (C m ) having an amplitude which varies as a function of time in accordance with the sample composition and wherein said chromatographic analyzer system is calibrated at a barometric pressure P c , the improvement comprising apparatus for compensating for errors in said output signal, said errors being produced by changes in barometric pressure from the barometric pressure P c , said apparatus comprising: means for establishing a first signal representative of the actual barometric pressure (P a ) at the time an analysis is made using said chromatographic analyzer system; means for determining the slope (M) of a plot of C m divided by the magnitude that C m would have if errors were not introduced by changes in barometric pressure (C a ) as a function of P a /P c for said detector means and for said sample; means for calculating a pressure compensation factor using P c , P a and M; and means for dividing said output signal by said pressure compensation factor to compensate for errors in said output signal produced by changes in barometric pressure from the barometric pressure P c .
Claim 3
Dependent Claim
20 words
Apparatus in accordance with claim 1 wherein said pressure compensation factor is equal to 1+M (P a /P c -1).
Claim 4
Dependent Claim
57 words
Apparatus in accordance with claim 2 wherein said means for determining the slope (M) comprises: means for analyzing a sample having a known composition at a plurality of different barometric pressures, as seen by said chromatographic analyzer system, to establish the values required for said plot; and means for calculating the slope of the experimentally determined plot.
Claim 5
Independent Claim
202 words
A method for compensating for errors in the output signal (C m ) from the detector associated with a chromatographic analyzer system used to analyze the composition of a sample, wherein said errors are caused by changes in barometric pressure with respect to the barometric pressure (P c ) at which said chromatographic analyzer was calibrated and wherein said output signal has an amplitude that varies as a function of time in accordance with the composition of said sample, said method comprising the steps of: establishing a first signal representative of the actual barometric pressure (P a ) at the time an analysis is made using said chromatographic analyzer system; determining the slope (M) of a plot of C m divided by the magnitude that C m would have if errors were not introduced by changes in barometric pressure (C a ) as a function of P a /P c for said detector means and for said sample; calculating a pressure compensation factor using P c , P a and M; and dividing said output signal by said pressure compensation factor to compensate for errors in said output signal produced by changes in barometric pressure from the barometric pressure P c .
Claim 6
Independent Claim
202 words
A method for compensating for errors in the output signal (C m ) from the detector associated with a chromatographic analyzer system used to analyze the composition of a sample, wherein said errors are caused by changes in barometric pressure with respect to the barometric pressure (P c ) at which said chromatographic analyzer was calibrated and wherein said output signal has an amplitude that varies as a function of time in accordance with the composition of said sample, said method comprising the steps of: establishing a first signal representative of the actual barometric pressure (P a ) at the time an analysis is made using said chromatographic analyzer system; determining the slope (M) of a plot of C m divided by the magnitude that C m would have if errors were not introduced by changes in barometric pressure (C a ) as a function of P a /P c for said detector means and for said sample; calculating a pressure compensation factor using P c , P a and M; and dividing said output signal by said pressure compensation factor to compensate for errors in said output signal produced by changes in barometric pressure from the barometric pressure P c .
Claim 7
Dependent Claim
21 words
A method in accordance with claim 4 wherein said pressure compensation factor is equal to 1+M (P a /P c -1).
Claim 8
Dependent Claim
54 words
A method in accordance with claim 5 wherein said step of determining the slope (M) comprises: analyzing a sample having a known composition at a plurality of different barometric pressures, as seen by said chromatographic analyzer system, to establish the values required for said plot; and calculating the slope of the experimentally determined plot.
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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) | 1988-04-22 | 1988-10-22 | 1989-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-22 | 1992-10-22 | 1993-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-22 | 1996-10-22 | 1997-04-23 | $7700.00 | Window Closed / Lapsed |