Method and apparatus for determination of an analyte and method of calibrating such apparatus

Claim 1

A method for calibrating a chemical analyzer useful in the determination of an analyte in an aqueous liquid, said analyzer comprising (a) spectrophotometric means for detecting "n" spectrophotometric responses A 1 , A 2 , . . . A n resulting when a sample of said liquid is contacted with an interactive composition for said analyte, and (b) means for calculating the concentration or activity C of said analyte in said sample using the equation (I): C=a.sub.0 +a.sub.1 [A.sub.1 +α.sub.1 A.sub.2 +. . . +α.sub.n-1 A.sub.n ] wherein a 0 , a 1 , α 1 , α 2 , . . . α n-1 are defined hereinafter, said method comprising the steps of: (A) from a multiplicity of patient test samples of unknown analyte concentration or activity, identifying first and second patient test samples having substantially the same analyte concentration or activity, said first sample exhibiting a significant bias in analyte concentration or activity and said second sample exhibiting no significant bias in analyte concentration or activity measured at a primary wavelength λ 1 ; (B) making a spectral absorption scan of each of said samples identified in step A; (C) identifying absorption bands from said spectral scans where differences in absorbance between said scans can be observed, and selecting at least one secondary wavelength from the group of secondary wavelengths λ 2 , λ 3 , . . . λ n representative of said absorption bands of both said first and second patient samples, respectively, wherein n represents the number of absorption bands; (D) using a multiplicity of patient test samples of known analyte concentration or activity, determining a linear regression line and its intercept and slopes using the equation (II): C=a.sub.0 +a.sub.1 A.sub.1 +a.sub.2 A.sub.2 + . . . +a.sub.n A.sub.n wherein C is analyte concentration or activity; a 0 is the intercept of said line; A 1 , A 2 , . . . A n are the spectrophotometric responses measured at λ 1 , λ 2 , . . . λ n respectively; and a 1 , a 2 , . . . a n are the slopes of said line relating said spectrophotometric responses at λ 1 , λ 2 , . . . λ n , respectively, to said analyte concentration or activity; (E) using the results of step D to determine constants α 1 , α 2 , . . . α n-1 for said equation (I) above using the equation (III): α.sub.i =(a.sub.i+1)/a.sub.1 wherein i=1 to (n-1); and (F) recording in said analyzer the values of said constants a 0 , a 1 , and α 1 , α 2 , . . . α n-1 for use in equation I above.

Claim 2

A method for calibrating a chemical analyzer useful in the determination of an analyte in an aqueous liquid, said analyzer comprising (a) spectrophotometric means for detecting "n" spectrophotometric responses A 1 , A 2 , . . . A n resulting when a sample of said liquid is contacted with an interactive composition for said analyte, and (b) means for calculating the concentration or activity C of said analyte in said sample using the equation (I): C=a.sub.0 +a.sub.1 [A.sub.1 +α.sub.1 A.sub.2 +. . . +α.sub.n-1 A.sub.n ] wherein a 0 , a 1 , α 1 , α 2 , . . . α n-1 are defined hereinafter, said method comprising the steps of: (A) from a multiplicity of patient test samples of unknown analyte concentration or activity, identifying first and second patient test samples having substantially the same analyte concentration or activity, said first sample exhibiting a significant bias in analyte concentration or activity and said second sample exhibiting no significant bias in analyte concentration or activity measured at a primary wavelength λ 1 ; (B) making a spectral absorption scan of each of said samples identified in step A; (C) identifying absorption bands from said spectral scans where differences in absorbance between said scans can be observed, and selecting at least one secondary wavelength from the group of secondary wavelengths λ 2 , λ 3 , . . . λ n representative of said absorption bands of both said first and second patient samples, respectively, wherein n represents the number of absorption bands; (D) using a multiplicity of patient test samples of known analyte concentration or activity, determining a linear regression line and its intercept and slopes using the equation (II): C=a.sub.0 +a.sub.1 A.sub.1 +a.sub.2 A.sub.2 + . . . +a.sub.n A.sub.n wherein C is analyte concentration or activity; a 0 is the intercept of said line; A 1 , A 2 , . . . A n are the spectrophotometric responses measured at λ 1 , λ 2 , . . . λ n respectively; and a 1 , a 2 , . . . a n are the slopes of said line relating said spectrophotometric responses at λ 1 , λ 2 , . . . λ n , respectively, to said analyte concentration or activity; (E) using the results of step D to determine constants α 1 , α 2 , . . . α n-1 for said equation (I) above using the equation (III): α.sub.i =(a.sub.i+1)/a.sub.1 wherein i=1 to (n-1); and (F) recording in said analyzer the values of said constants a 0 , a 1 , and α 1 , α 2 , . . . α n-1 for use in equation I above.

Claim 7

A method for the determination of an analyte in an aqueous liquid, said method comprising the steps of: (A*) physically contacting a sample of said liquid with an interactive composition for said analyte; (B*) measuring the spectrophotometric responses A 1 , A 2 , . . . A n resulting from said contact at, respectively, a primary wavelength λ 1 and at n secondary wavelengths selected from secondary wavelengths λ 2 , λ 3 , . . . λ n ; and (C*) determining the concentration or activity C of said analyte using the equation (I): C=a.sub.0 +a.sub.1 (A.sub.1 +α.sub.1 A.sub.2 + . . . +α.sub.n-1 A.sub.n) wherein the constants a 0 , a 1 and α 1 , α 2 , . . . α n-1 and said secondary wavelengths λ 2 , λ 3 , . . . λ n are determined according to a calibration method for as many n secondary wavelengths as are used in said step (B*), said calibration method comprising the steps: (A) from a multiplicity of patient test samples of unknown analyte concentration or activity, identifying first and second patient test samples having substantially the same analyte concentration or activity, said first sample exhibiting a significant bias in analyte concentration or activity and said second sample exhibiting no significant bias in analyte concentration or activity measured at a primary wavelength λ 1 ; (B) making a spectral absorption scan of each of said samples identified in step A; (C) identifying absorption bands from said spectral scans where differences in absorbance between said scans can be observed, and selecting at least one secondary wavelength from the group of secondary wavelengths λ 2 , λ 3 , . . . λ n representative of said absorption bands of both said first and second patient samples, respectively, wherein n represents the number of absorption bands; (D) using a multiplicity of patient test samples of known analyte concentration or activity, determining a linear regression line and its intercept and slopes using the equation (II): C=a.sub.0 +a.sub.1 A.sub.1 +a.sub.2 A.sub.2 + . . . +a.sub.n A.sub.n wherein C is analyte concentration or activity; a 0 is the intercept of said line; A 1 , A 2 , . . . A n are the spectrophotometric responses measured at λ 1 , λ 2 , . . . λ n respectively; and a 1 , a 2 , . . . a n are the slopes of said line relating said spectrophotometric responses at λ 1 , λ 2 , . . . λ n , respectively, to said analyte concentration or activity; (E) using the results of step D to determine constants α 1 , α 2 , . . . α n-1 for said equation (I) above using the equation (III): α.sub.i =(a.sub.i+1)/a.sub.1 wherein i=1 to (n-1); and (F) recording in said analyzer the values of said constants a 0 , a 1 , and α 1 , α 2 , . . . α n-1 for use in equation I above.

Claim 8

A method for the determination of an analyte in an aqueous liquid, said method comprising the steps of: (A*) physically contacting a sample of said liquid with an interactive composition for said analyte; (B*) measuring the spectrophotometric responses A 1 , A 2 , . . . A n resulting from said contact at, respectively, a primary wavelength λ 1 and at n secondary wavelengths selected from secondary wavelengths λ 2 , λ 3 , . . . λ n ; and (C*) determining the concentration or activity C of said analyte using the equation (I): C=a.sub.0 +a.sub.1 (A.sub.1 +α.sub.1 A.sub.2 + . . . +α.sub.n-1 A.sub.n) wherein the constants a 0 , a 1 and α 1 , α 2 , . . . α n-1 and said secondary wavelengths λ 2 , λ 3 , . . . λ n are determined according to a calibration method for as many n secondary wavelengths as are used in said step (B*), said calibration method comprising the steps: (A) from a multiplicity of patient test samples of unknown analyte concentration or activity, identifying first and second patient test samples having substantially the same analyte concentration or activity, said first sample exhibiting a significant bias in analyte concentration or activity and said second sample exhibiting no significant bias in analyte concentration or activity measured at a primary wavelength λ 1 ; (B) making a spectral absorption scan of each of said samples identified in step A; (C) identifying absorption bands from said spectral scans where differences in absorbance between said scans can be observed, and selecting at least one secondary wavelength from the group of secondary wavelengths λ 2 , λ 3 , . . . λ n representative of said absorption bands of both said first and second patient samples, respectively, wherein n represents the number of absorption bands; (D) using a multiplicity of patient test samples of known analyte concentration or activity, determining a linear regression line and its intercept and slopes using the equation (II): C=a.sub.0 +a.sub.1 A.sub.1 +a.sub.2 A.sub.2 + . . . +a.sub.n A.sub.n wherein C is analyte concentration or activity; a 0 is the intercept of said line; A 1 , A 2 , . . . A n are the spectrophotometric responses measured at λ 1 , λ 2 , . . . λ n respectively; and a 1 , a 2 , . . . a n are the slopes of said line relating said spectrophotometric responses at λ 1 , λ 2 , . . . λ n , respectively, to said analyte concentration or activity; (E) using the results of step D to determine constants α 1 , α 2 , . . . α n-1 for said equation (I) above using the equation (III): α.sub.i =(a.sub.i+1)/a.sub.1 wherein i=1 to (n-1); and (F) recording in said analyzer the values of said constants a 0 , a 1 , and α 1 , α 2 , . . . α n-1 for use in equation I above.