Method for spectrophotometric compensation for colorimetric reagent variation

Claim 1

A method for spectrophotometrically compensating for error in the amount of indicator added to a sample in bleaching chemistry analyses comprising, (a) adding to said sample a reagent system comprising an indicator whose absorbance at a first wavelength is a function of the amount of a parameter of interest in said sample and a dye whose absorbance at a second wavelength is equal to the absorbance of said indicator at said first wavelength at zero concentration parameter so that the dye provides a reference against which any change in absorbance may be measured; (b) measuring the absorbance at said first and second wavelengths; (c) finding the difference of the absorbance at said first wavelength from the absorbance at said second wavelength; and (d) relating said difference of absorbances to the amount of the parameter of interest in said sample.

Claim 2

A method for spectrophotometrically compensating for error in the amount of indicator added to a sample in bleaching chemistry analyses comprising, (a) adding to said sample a reagent system comprising an indicator whose absorbance at a first wavelength is a function of the amount of a parameter of interest in said sample and a dye whose absorbance at a second wavelength is equal to the absorbance of said indicator at said first wavelength at zero concentration parameter so that the dye provides a reference against which any change in absorbance may be measured; (b) measuring the absorbance at said first and second wavelengths; (c) finding the difference of the absorbance at said first wavelength from the absorbance at said second wavelength; and (d) relating said difference of absorbances to the amount of the parameter of interest in said sample.

Claim 4

A method for spectrophotometrically compensating for mixing and metering variations in bleaching chemistry analyses in a single beam dual wavelength chemical analyzer, comprising, in successive samples under test, (a) adding to said sample a reagent system capable of absorbing radiant energy at two wavelengths, the absorbance at a first wavelength being a function of an amount of a parameter in said sample and the absorbance at a second wavelength being a function of said reagent system added to said sample to conduct the tests, said absorbances at said first and second wavelengths being equal at zero parameter concentration; (b) detecting the radiant energy at said wavelengths with a sensing means that has an output signal indicative of the radiant energy detected; (c) finding the difference of the logarithm of said sensing means signal at the first wavelength from the logarithm of the sensing means signal at said second wavelength; and (d) relating said difference of logarithms to the amount of the parameter of interest.

Claim 5

A method for spectrophotometrically compensating for mixing and metering variations in bleaching chemistry analyses in a single beam dual wavelength chemical analyzer, comprising, in successive samples under test, (a) adding to said sample a reagent system capable of absorbing radiant energy at two wavelengths, the absorbance at a first wavelength being a function of an amount of a parameter in said sample and the absorbance at a second wavelength being a function of said reagent system added to said sample to conduct the tests, said absorbances at said first and second wavelengths being equal at zero parameter concentration; (b) detecting the radiant energy at said wavelengths with a sensing means that has an output signal indicative of the radiant energy detected; (c) finding the difference of the logarithm of said sensing means signal at the first wavelength from the logarithm of the sensing means signal at said second wavelength; and (d) relating said difference of logarithms to the amount of the parameter of interest.