US4238830A
Expired / Lapsed
US
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Curvature correction
Assignee: Applied Biosystems Inc
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Filing: 1979-08-01
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Granted: 1980-12-09
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Expires: 1999-08-01
Abstract
Abstract In a dual beam atomic absorption spectrometer having a dedicated microcomputer, improved calibration constants are obtained from either two or three known concentration values by finding a number of constants equal to the number of samples such that when the excess over one of the absorbance of that sample of known concentration multiplied by a second constant is divided into the first constant times the absorbance raised to a power one less than the number of samples or in the case of three samples the difference between that value and a third constant times the absorbance, for each measured sample, the result is equal to the known concentration of the sample.
Inventors
- 👤 Hoshang A. Unvala
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:51
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/3103
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
225 words
In a photometric instrument in which radiant energy measurements are taken and used to determine a concentration, and in which the relationship between measured radiant energy values and concentration is non-linear over the full range desired to be measured, a method of correcting for the curvature which exists in the relationship comprising: (a) measuring the radiant energy with respect to at least two and not more than three samples of known concentration; (b) storing said known concentrations and their associated measured values; (c) determining in computing apparatus a number of constants equal to the number of samples which are such that, with two measured samples, the excess over one of a second constant times the measured value divided into a first constant times the measured value and, with three samples, said excess divided into a quantity equal to said first constant times the measured value squared minus a third constant times the measured value, for each sample, is equal to the known concentration; (d) storing said determined constants; (e) measuring such radiant energy with respect to an unknown sample and storing the measured value; (f) using the measured value of said unknown sample and said stored constants in said computing apparatus to determine the concentration of said unknown using the same relationship used to determine said constants; and (g) storing and displaying said unknown concentration.
Claim 2
Dependent Claim
225 words
In a photometric instrument in which radiant energy measurements are taken and used to determine a concentration, and in which the relationship between measured radiant energy values and concentration is non-linear over the full range desired to be measured, a method of correcting for the curvature which exists in the relationship comprising: (a) measuring the radiant energy with respect to at least two and not more than three samples of known concentration; (b) storing said known concentrations and their associated measured values; (c) determining in computing apparatus a number of constants equal to the number of samples which are such that, with two measured samples, the excess over one of a second constant times the measured value divided into a first constant times the measured value and, with three samples, said excess divided into a quantity equal to said first constant times the measured value squared minus a third constant times the measured value, for each sample, is equal to the known concentration; (d) storing said determined constants; (e) measuring such radiant energy with respect to an unknown sample and storing the measured value; (f) using the measured value of said unknown sample and said stored constants in said computing apparatus to determine the concentration of said unknown using the same relationship used to determine said constants; and (g) storing and displaying said unknown concentration.
Claim 3
Dependent Claim
15 words
The method according to claim 1 wherein said measured values reflect absorbance of the samples.
Claim 4
Dependent Claim
15 words
The method according to claim 1 wherein said measured values reflect emission of the samples.
Claim 5
Dependent Claim
68 words
The method according to claim 1 wherein said instrument is an atomic absorption spectrophotometer including means for providing an analog signal proportional to the intensity of light reaching the sample divided by the intensity of light transmitted through the sample, and further including the step of taking the log of said analog signal to obtain a log value and storing said log value as the value of absorbance.
Claim 6
Dependent Claim
30 words
The method according to claim 4 wherein said log value is an analog for and said method includes the further step of converting said log value to a digital value.
Claim 7
Dependent Claim
20 words
The method according to claim 5 further including the step of integrating said analog value over a predetermined cycle time.
Claim 8
Dependent Claim
47 words
The method according to claim 5 wherein said apparatus includes programmed digital computing means having a predetermined cycle time and receiving input data once during each cycle and said method further includes the step of measuring the peak value of said analog value during said cycle time.
Claim 9
Dependent Claim
164 words
In a photometric instrument in which radiant energy measurements are taken and used to determine a concentration, and in which the relationship between measured radiant energy values and concentration is non-linear over the full range desired to be measured, apparatus for correcting the curvature which exists in the relationship, comprising: (a) means for making radiant energy measurements; (b) computing means for (1) storing the known concentration values of two measured samples of known concentration and their associated measured radiant energy values; (2) determining two constants which are such that the excess over one of a second constant times the measured energy value divided into a first constant times the measured energy value, for each sample, is equal to the known concentration; (3) storing the measured energy values of samples of unknown concentrations; and (4) using said measured energy values of unknown samples and said stored constants to determine the concentration of said unknown samples; and (c) means for storing and displaying said unknown concentration.
Claim 10
Dependent Claim
164 words
In a photometric instrument in which radiant energy measurements are taken and used to determine a concentration, and in which the relationship between measured radiant energy values and concentration is non-linear over the full range desired to be measured, apparatus for correcting the curvature which exists in the relationship, comprising: (a) means for making radiant energy measurements; (b) computing means for (1) storing the known concentration values of two measured samples of known concentration and their associated measured radiant energy values; (2) determining two constants which are such that the excess over one of a second constant times the measured energy value divided into a first constant times the measured energy value, for each sample, is equal to the known concentration; (3) storing the measured energy values of samples of unknown concentrations; and (4) using said measured energy values of unknown samples and said stored constants to determine the concentration of said unknown samples; and (c) means for storing and displaying said unknown concentration.
Claim 11
Dependent Claim
178 words
In a photometric instrument in which radiant energy measurements are taken and used to determine a concentration, and in which the relationship between measured radiant energy values and concentration is non-linear over the full range desired to be measured, apparatus for correcting the curvature which exists in the relationship, comprising: (a) means for making radiant energy measurements; (b) computing means for (1) storing the known concentration values of three measured samples of known concentration and their associated measured radiant energy values; (2) determining three constants which are such that, the excess over one of a second constant times the measured energy value divided into a quantity equal to a first constant times the measured energy value squared minus a third constant times the measured energy value, for each sample, is equal to the known concentration; (3) storing the measured energy values of samples of unknown concentrations; and (4) using said measured energy values of unknown samples and said stored constants to determine the concentration of said unknown samples; and (c) means for storing and displaying said unknown concentration.
Claim 12
Dependent Claim
178 words
In a photometric instrument in which radiant energy measurements are taken and used to determine a concentration, and in which the relationship between measured radiant energy values and concentration is non-linear over the full range desired to be measured, apparatus for correcting the curvature which exists in the relationship, comprising: (a) means for making radiant energy measurements; (b) computing means for (1) storing the known concentration values of three measured samples of known concentration and their associated measured radiant energy values; (2) determining three constants which are such that, the excess over one of a second constant times the measured energy value divided into a quantity equal to a first constant times the measured energy value squared minus a third constant times the measured energy value, for each sample, is equal to the known concentration; (3) storing the measured energy values of samples of unknown concentrations; and (4) using said measured energy values of unknown samples and said stored constants to determine the concentration of said unknown samples; and (c) means for storing and displaying said unknown concentration.
Claim 13
Dependent Claim
213 words
In a photometric instrument in which radiant energy measurements are taken and used to determine a concentration, and in which the relationship between measured radiant energy values and concentration is non-linear over the full range desired to be measured, apparatus for correcting the curvature which exists in the relationship, comprising: (a) means for making radiant energy measurements; (b) computing means for (1) storing the known concentration values of at least two and not more than three measured samples of known concentration and their associated measured radiant energy values; (2) determining a number of constants equal to the number of samples which are such that, with two measured samples, the excess over one of a second constant times the measured energy value divided into a first constant times the measured energy value and, with three samples, said excess divided into a quantity equal to said first constant times the measured energy value squared minus a third constant times the measured energy value, for each sample, is equal to the known concentration; (3) storing the measured energy values of samples of unknown concentrations; and (4) using said measured energy values of unknown samples and said stored constants to determine the concentration of said unknown samples; and (c) means for storing and displaying said unknown concentration.
Claim 14
Dependent Claim
213 words
In a photometric instrument in which radiant energy measurements are taken and used to determine a concentration, and in which the relationship between measured radiant energy values and concentration is non-linear over the full range desired to be measured, apparatus for correcting the curvature which exists in the relationship, comprising: (a) means for making radiant energy measurements; (b) computing means for (1) storing the known concentration values of at least two and not more than three measured samples of known concentration and their associated measured radiant energy values; (2) determining a number of constants equal to the number of samples which are such that, with two measured samples, the excess over one of a second constant times the measured energy value divided into a first constant times the measured energy value and, with three samples, said excess divided into a quantity equal to said first constant times the measured energy value squared minus a third constant times the measured energy value, for each sample, is equal to the known concentration; (3) storing the measured energy values of samples of unknown concentrations; and (4) using said measured energy values of unknown samples and said stored constants to determine the concentration of said unknown samples; and (c) means for storing and displaying said unknown concentration.
Claim 15
Dependent Claim
27 words
Apparatus according to claim 10 or claim 8 or claim 15 wherein said photometric instrument is an atomic absorption spectrophotometer and said measured energy values reflect absorbance.
Claim 16
Dependent Claim
84 words
Apparatus according to claim 10 or claim 8 or claim 9 wherein said instrument is an atomic absorption spectrophotometer including means for providing an analog signal proportional to the intensity of light reaching the sample divided by the intensity of light transmitted through the sample, and in which absorbance is equal to the log of this signal and further including a log converter for taking the log of said signal and means for storing said log as the value of absorbance in analog form.
Claim 17
Dependent Claim
31 words
Apparatus according to claim 12 wherein said computing means is digital computing means and further including an analog-to-digital converter for converting the output of said logrithmic converter to a digital value.
Claim 18
Dependent Claim
50 words
Apparatus according to claim 13 wherein said digital computing means has a predetermined cycle time and receives input data once during each cycle and further including means for integrating interposed between said log converter and said analog-to-digital converter for integrating the output of said log converter over said cycle time.
Claim 19
Dependent Claim
49 words
Apparatus according to claim 13 wherein said digital computing means has a predetermined cycle time and receives input data once during each cycle and further including means interposed between said log converter and said analog-to-digital converter for measuring the peak value of said log converter during said cycle time.
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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) | 1983-12-09 | 1984-06-09 | 1984-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-09 | 1988-06-09 | 1988-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-09 | 1992-06-09 | 1992-12-09 | $7700.00 | Window Closed / Lapsed |