US 12,429,419 B2Granted

IR spectra matching systems and methods

AssigneeMissouri State University

InventorsRazib Iqbal, Keiichi Yoshimatsu, Joshua Ellis

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Abstract

Spectra matching is widely used in various applications including the search for a spectrum of an unknown or subject material, chemical, or compound in an existing spectral database and quality control by means of comparing the spectra of products with standards. New systems and methods are described for identifying an unknown compound by calculating the similarities of Fourier-transform infrared (FTIR) spectra of organic compounds. The systems and methods incrementally calculate the spectral similarity based on the local spectral shapes. This reduces the bias caused by uneven weighing of large or broader peaks. In addition, the new systems and methods tolerant to the common issues in spectra matching including baseline offset, baseline sloping, and deviations in wavenumber axis alignment, suggesting its robustness and practical applicability.

Claims16

Dependent claims

A method for identifying a subject material having a subject spectrum, the method comprising:

obtaining the subject spectrum for the subject material by optically collecting data associated with the subject material;
and calculating a final set of normalized local change values for the subject spectrum by:
determining a set of ranges for each discrete wavenumber value of a plurality of discrete wavenumber values such that each set of ranges corresponds with a single discrete wavenumber and each discrete wavenumber corresponds with a single set of ranges, wherein each set of ranges includes including an upper wavenumber range and a lower wavenumber range;
determining for each discrete wavenumber value respective first and second values associated with respective upper and lower wavenumber ranges, respectively;
and calculating for each discrete wavenumber value a normalized local change value by dividing the respective first value by the sum of the respective first and second values, wherein each upper wavenumber range extends between respective first and second upper wavenumber values, wherein each lower wavenumber range extends between respective first and second lower wavenumber values, wherein each normalized local change value of each final set of normalized local change values is between zero and one.

2 more elements

A method for identifying a reference spectrum for an unknown subject spectrum from among a plurality of reference spectra, the subject spectrum and each reference spectrum comprising a plurality of discrete wavenumber values, each discrete wavenumber value being associated with respective upper and lower wavenumber ranges, the method comprising:

calculating a final spectral similarity value for each reference spectrum using a final set of normalized local change values for the subject spectrum and a final set of normalized local change values for the relevant reference spectrum;
identifying a maximum final spectral similarity value of the calculated final spectral similarity values;
and
identifying the reference spectrum for the unknown subject spectrum as the reference spectrum associated with the maximum spectral similarity value,
wherein calculating the final spectral similarity value for a first reference spectrum comprises:
comparing normalized local change values for each discrete wavenumber of the first reference spectrum with normalized local change values of the corresponding discrete wavenumber value of the subject spectrum;
and
comparing normalized local change values for each discrete wavenumber value of the first reference spectrum with normalized local change values that are shifted a first value from the corresponding discrete wavenumber value of the subject spectrum.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/233,431Filed 14 Aug 2023 · continuation
Priority: 7 Mar 2019
Published: US 2024/0219299 A14 Jul 2024
Granted: 30 Sep 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01N 21/35
Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry:…
G01J 3/28
Spectrometry; Spectrophotometry; Monochromators; Measuring colours: investigating the spectrum
G01N 2021/3196
Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry:…
G01N 2021/3595
Using infrared light: using FTIR

Family

Application62/815,093Us provisional application · filed 7 Mar 2019
Application16/811,680Parent of this continuation · filed 6 Mar 2020
US 2024/0219299 A1Pre-grant publication · published 4 Jul 2024
US 11,726,034 B2Parent of this continuation
US 2020/0284719 A1Published application
US 12,429,419 B2This patent

From the US filing history. Foreign family members aren’t listed.