US 5,706,208 AGranted

Method for the prediction of properties of biological matter by analysis of the near-infrared spectrum thereof

AssigneesMinnesota Mining and Manufacturing Company, The Board of Regents of the University of Washington

InventorsDavid W. Osten, James B. Callis

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Abstract

A method for predicting a property of a matter of biological origin, such as biological fluid, containing water, where the biological matter may be approximated to contain two compartments where one compartment has a proportionally larger or smaller amount of water than the other compartment having the property of interest. The method establishes a training set in the near-infrared (NIR) region with independent quantification of the property of the matter using known techniques. The training set is mathematically analyzed according to a correlation developed by regression analysis after employment of a ratio pre-processing technique. The result is a mathematical transformation equation which quantitatively relates spectral intensities at specific wavelengths to the property of interest. This transformation equation may be applied to unknown samples so as to predict their properties, thereby eliminating need for the reference method except for validation or recalibration. There is rapid and accurate prediction of the property of the unknown sample, which may be the property of hematocrit or hemoglobin concentration in whole animal blood.

A method for analyzing a property of biological matter having a water content, the biological matter approximated to comprise a first compartment related to the property to be analyzed and a second compartment having a proportionally different amount of water than the first compartment, the method comprising:

(a) obtaining multiple samples of biological matter from at least one known organism of a given species;
(b) irradiating with near infrared light said multiple samples;
(c) detecting a near infrared spectrum of each of said multiple samples as spectral data consisting of absorbance intensities;
(d) applying a ratio pre-processing technique to the spectral data of absorbance intensities of the spectrum of each of said multiple samples to identify a multiplicity of ratio wavelength pairs;
(e) independently quantifying the property to be analyzed for each of said multiple samples;
(f) establishing a training set from said near infrared spectra from step (d) of said multiple samples using the multiplicity of ratio wavelength pairs;
(g) statistically identifying a nature of a best two compartment mathematical correlation between the property to be analyzed in the first compartment and the water content in the biological matter (1) by correlating values obtained during step (e) with values obtained during step (f) and (2) by selecting a ratio wavelength pair of absorbance intensities in which one wavelength is a near infrared wavelength absorbance peak of the water content and in which the second wavelength of the ratio wavelength pair is another near infrared wavelength absorbance measuring point having absorbances in the first compartment which minimize variability in the property to be analyzed;
(h) obtaining an unknown sample of biological matter from an organism of said given species;
(i) irradiating said unknown sample with near infrared light;
(j) detecting near infrared absorbance of said unknown sample at said near infrared wavelength absorbance peak of the water content and at said another near infrared wavelength absorbance measuring point as spectral data consisting of absorbance intensities;
(k) applying said ratio pre-processing technique using the ratio wavelength pair selected in step (g) to the spectral data of absorbance intensities of said near infrared absorbance peak of the water content and said another near infrared wavelength absorbance measuring point;
and
(l) predicting the property to be analyzed in said unknown sample by utilizing said best two compartment mathematical correlation obtained in said statistically identifying step (g).

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Abstract

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