Optical compositional analyzer apparatus and method for detection of ash in wheat and milled wheat products

• US 5,258,825 A
• Filed: 11/13/1991
• Issued: 11/02/1993
• Est. Priority Date: 11/13/1991
• Status: Expired due to Term

• Current Assignee: Perten Instruments North America, Inc.
• Original Assignee: Perten Instruments North America, Inc.
• Inventors: Psotka, James J., Reed, David S.
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US07/791,884
• Time in Patent Office: 720 Days
• Field of Search: 356/39, 356/40, 356/41, 356/51, 356/402, 356/407, 356/414, 356/416, 356/419, 356/420, 250/339, 250/338.5, 250/341
• US Class Current: 356/402
• CPC Class Codes: G01N 2021/3114 Multi-element AAS arrangements
• CPC Class Codes: G01N 2021/3129 Determining multicomponents by multiwavelength light
• CPC Class Codes: G01N 2021/3155 Measuring in two spectral ranges, e.g. UV and visible
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 2201/065 Integrating spheres
• CPC Class Codes: G01N 33/10 Starch-containing substances, e.g. dough
• CPC Class Codes: Y10S 250/91 Food sample analysis using invisible radiant energy source

Abstract

An optical analyzing apparatus (20) for obtaining a quantitative correlation spectroscopy measurements of an analyte concentration in a multiple constituent sample (24). The optical analyzing apparatus (20) employs a correlation spectroscopy algorithm which uses preselected wavelength light energy from both the visible light spectrum and the near-infrared (NIR) light spectrum to analyze multiconstituent samples. The optical analyzing apparatus (20) comprises a light emitter mechanism (22) formed for irradiating the sample (24) with a predetermined first wavelength of light energy in the visible light spectrum and a predetermined second wavelength of light energy in the NIR spectrum. The first wavelength is selected to be active in response to the presence of the analyte while the second wavelength is selected to be active in response to the presence of at least one of the remaining constituents in the sample (24). A detector mechanism (50) is positioned to detect one of optical reflectance and transmissivity of the sample (24) after irradiation at the first and second wavelength, whereby the detected one of reflectance and transmissivity can be used in correlation spectroscopy algorithms to obtain a value of the concentration.

Claims

1. An optical analyzing apparatus for obtaining quantitative compositional correlation spectroscopy measurements of an analyte concentration in a multiple constituent flour product sample, said optical analyzing apparatus comprising:

light emitter means formed for irradiating said sample with a predetermined first wavelength of light energy in the visible light spectrum in the range between about 530 nm to about 550 nm selected to be active in response to the presence of said analyte, and a predetermined second wavelength of light energy in the near-infrared (NIR) spectrum in the range between about 1350 nm to about 1370 nm selected to be active in response to the presence of at least one of the remaining constituents in the sample; and

detector means positioned to detect one of optical reflectance and transmissivity of the ample after said irradiation at said first wavelength and said second wavelength, whereby

the detected one of reflectance and transmissivity can be used in a compositional correlation spectroscopy algorithm to obtain a value of said concentration.

2. The optical analyzing apparatus as defined in claim 1 further including:

computation means coupled to said detector means for calculating said value from the detected one of reflectance and transmissivity of the sample using said algorithm.

3. The optical analyzing apparatus as defined in claim 2 wherein,

said computation means includes means for determining the value of said concentration in accordance with the following compositional correlation spectroscopy algorithm:

space="preserve" listing-type="equation">%.sub.Analyte =a.sub.0 +a.sub.1 log(1/R.sub.1)+a.sub.2 log(1/R.sub.2)

in which the constants a₀, a₁ and a₂ are constants having predetermined values, R₁ is the reflectance from the sample due to said predetermined visible light wavelength, and R₂ is the reflectance from the sample due to said predetermined NIR light wavelength.

4. The optical analyzing apparatus as defined in claim 1 wherein,

said light emitter means comprising a wide band wavelength light, first filter means positioned between said light and said sample and permitting irradiation of said sample by said first wavelength of light energy, and second filter means positioned between said light and said sample and permitting irradiation of said sample by said second wavelength of light energy.

5. The optical analyzing apparatus as defined in claim 4 wherein,

said light is a quartz tungsten-halogen light source.

6. The optical analyzing apparatus as defined in claim 4 wherein,

said first filter means and said second filter means are preselected interference filters.

7. The optical analyzing apparatus as defined in claim 4 wherein,

said first and second filter means are fixed to a rotatable turret means operable to sequentially rotate said first and second filters between said light and said sample.

8. The optical analyzing apparatus as defined in claim 1 wherein,

said light emitter means comprise a light emitting diode (LED) emitting light corresponding to said first wavelength of light energy, and a NIR emitting diode (NIRED) emitting light corresponding to said second wavelength of light energy.

9. The optical analyzing apparatus as defined in claim 1 wherein,

said light emitter means sequentially irradiates said sample with said first wavelength of light energy and with said second wavelength of light energy.

10. The optical analyzing apparatus as defined in claim 1 wherein,

said flour product sample is provided by wheat flour and said analyte is any one of bran and cellulose.

11. The optical analyzing apparatus as defined in claim 1 wherein,

said first wavelength of visible light energy is about 540 nm.

12. The optical analyzing apparatus as defined in claim 1 wherein,

said first wavelength of visible light energy is about 540 nm, and said second wavelength of NIR light energy is about 1360 nm.

13. The optical analyzing apparatus as defined in claim 1 wherein,

said second wavelength of NIR light energy is about 1360 nm.

14. The optical analyzing apparatus as defined in claim 1 wherein,

said sample is positioned for irradiation in an integrating sphere and said detector means are strategically located therein.

15. An optical analyzing apparatus for obtaining a compositional quantitative measurement of an analyte concentration in a multiple constituent flour product sample, said optical analyzing apparatus comprising:

light emitter means formed for irradiating the sample with light energy;

first filter means positioned between said light emitter means and said sample, and permitting irradiation of said sample by predetermining wavelength of light energy in the visible light spectrum in the range between about 530 nm to about 550 nm selected to be active in response to the presence of said analyte;

second filter means positioned between said light emitter means and said sample, and permitting irradiation of said sample by a predetermined wavelength of light energy in the near-infrared (NIR) spectrum in the range between about 1350 nm to about 1370 nm selected to be active in response to the presence of at least one of the remaining constituents in the sample;

detector means positioned to detect one of optical reflectance and transmissivity of the sample after said irradiation at said wavelength in the NIR spectrum and said wavelength in the visible spectrum; and

computation means coupled to said detector means for calculating said compositional quantitative measurement from the detected one of reflectance and transmissivity of the sample.

16. The optical analyzing apparatus as defined in claim 15 wherein,

said first filter means and said second filter means are preselected interference filters.

17. The optical analyzing apparatus as defined in claim 15 wherein,

said irradiation of said sample with said first wavelength of light energy and with said second wavelength of light energy is sequential.

18. The optical analyzing apparatus as defined in claim 15 wherein,

said product sample is provided by wheat flour.

19. The optical analyzing apparatus as defined in claim 18 wherein,

said analyte is any one of bran and cellulose.

20. The optical analyzing apparatus as defined in claim 15 wherein,

said first wavelength of visible light energy is about 540 nm.

21. The optical analyzing apparatus as defined in claim 20 wherein,

said second wavelength of NIR light energy is about 1360 nm.

22. In an optical analyzing apparatus for obtaining quantitative compositional correlation spectroscopy measurements of flour "ash" concentration in a multiple constituent wheat flour sample, said optical analyzing apparatus including light emitter means formed for irradiating said sample with light energy and detector means positioned to detect one of optical reflectance and transmissivity of the sample after said irradiation, said detected one of reflectance and transmissivity can be used in a compositional correlation spectroscopy algorithm to obtain a value of said concentration, wherein the improvement comprises:

said light emitter means irradiating said sample with a predetermined first wavelength of light energy in the visible light spectrum in the range between about 530 nm to about 550 nm selected to be active in response to the presence of said flour "ash", and a predetermined second wavelength of light energy in the near-infrared (NIR) spectrum in the range between about 1350 nm to about 1370 nm selected to be active in response to the presence of at least one of the remaining constituents in the sample.

23. The optical analyzing apparatus as defined in claim 22 wherein,

said flour "ash" includes any one of bran and cellulose.

24. The optical analyzing apparatus as defined in claim 22 wherein,

said first wavelength of visible light energy is about 540 nm.

25. The optical analyzing apparatus as defined in claim 22 wherein,

said first wavelength of visible light energy is about 540 nm, and said second wavelength of NIR light energy is about 1360 nm.

26. The optical analyzing apparatus as defined in claim 22 wherein,

said second wavelength of NIR light energy is about 1360 nm.

27. A method for optically obtaining quantitative compositional correlation spectroscopy measurements of an anlayte concentration in a multiple constituent flour product sample, said method comprising the steps of:

irradiating said flour product sample with a predetermined first wavelength of light energy in the visible light spectrum selected to be active in response to the presence of said analyte;

detecting one of a first optical reflectance and a first optical transmissivity of the flour product sample after said irradiation at said first wavelength;

irradiating said flour product sample with a predetermined second wavelength of light energy in the near-infrared (NIR) spectrum selected to be active in response to the presence of at least one of the remaining constituents in the flour product sample;

detecting one of a second optical reflectance and a second optical transmissivity of the flour product sample after said irradiation at said second wavelength;

calculating a value of said concentration of said analyte using a compositional correlation spectroscopy algorithm from said first and said second detected one of reflectance and transmissivity of the flour product sample.

28. The method as defined in claim 27 wherein,

said step of irradiating said sample with a first wavelength of light energy is accomplished by irradiating said sample with visible light energy having a wavelength in the range of about 530 nm to about 550 nm.

29. The method as defined in claim 28 wherein, said step of irradiating said sample with a second wavelength of light energy is accomplished by irradiating said sample with NIR energy having a wavelength in the range of about 1350 nm to about 1370 nm.

30. The method as defined in claim 29 wherein,

said step of irradiating said sample with a first wavelength of light energy is accomplished by irradiating said sample with visible light energy having a wavelength of about 540 nm;

and

said step of irradiating said sample with a second wavelength of light energy is accomplished by irradiating said sample with NIR light energy having a wavelength of about 1360 nm.