Method for analyzing one ingredient of a three ingredient mixture

• US 4,136,959 A
• Filed: 01/28/1977
• Issued: 01/30/1979
• Est. Priority Date: 01/28/1976
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Honkawa, Tadashi, Komori, Ritsuo
• Primary Examiner(s): McGraw, Vincent P.
• Assistant Examiner(s): Bovernick, Rodney B.
• Application Number:
  US05/763,674
• Time in Patent Office: 732 Days
• Field of Search: 356/180, 356/188, 356/184, 356/178, 356/199, 356/201
• US Class Current: 356/418
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: Y10S 250/91 Food sample analysis using invisible radiant energy source

Abstract

A three ingredient mixture is eradiated with light rays of two separate wave lengths selected at which the absorption spectra of at least two of the materials of the mixture intersect. The light rays passing through the materials are detected and separated electrically so that they are processed with coefficients determined from ratios involving the absorption of at least two of the materials, so that the difference in the signals so obtained is quantitatively correlated to only one of the materials in the mixture.

Claims

1. A method for quantitatively analyzing one ingredient in a mixture of three ingredients comprising the steps of:

passing light rays of a first wavelength and a second wavelength through the mixture of the three ingredients, with the first and second wavelengths being selected at which the absorption spectra of at least two of the materials of the mixture intersect;

detecting the light waves of the first wavelength transmitted through said mixture and the light rays of the second wavelength transmitted through said mixture and producing first and second electric signals proportional to the transmittance of the first and second wavelengths through the mixture;

electrically logrithmically converting the first and second electric signals respectively into third and fourth electrical signals correlated to the absorbance of the light rays of the first wavelength and the light rays of the second wavelength in the mixture;

determining one wavelength at which the absorbance of the second and third materials is identical and another separate wavelength at which the absorbance of the second and third materials are identical and measuring the absorbance of the second and third materials at said one and another wavelengths to obtain first and second coefficients having a ratio with respect to each other that is substantially equal to the ratio of the absorbance of the another wavelength in said second material to the absorbance of the one wavelength in said second material, which is substantially equal to the ratio of the absorbance of the another wavelength in said third material to the absorbance of said one wavelength in said third material; and

multiplying said third and fourth electric signals by said first and second coefficients, respectively, to obtain fifth and sixth electric signals;

differentially amplifying said fifth and sixth electric signals to obtain a seventh differential signal that is quantitatively correlated to only said first material in the mixture.