Methodology for the identification of materials through methods of comparison of the spectrum of a sample against a reference library of spectra of materials

1. Method of comparison of spectra from a sample spectrum and at least one spectrum of a reference library, the method comprising the steps of:

obtaining at least one relevant spectral peak from the sample spectrum, and

comparing each of the relevant spectral peaks with the spectra in the reference library,

wherein:

the relevant spectral peaks are identified from a sample spectrum variation parameter, and

the relevant spectral peaks are obtained within a region of interest in the sample spectrum.

2. The method of comparison of spectra according to claim 1 , wherein:

each of the reference library spectra comprises at least one reference spectral peak, and

the method further comprises the step of comparing each of the relevant spectral peaks of the sample with each of the reference spectral peaks of the reference spectra.

3. The method of comparison of spectra according to claim 2 , further comprising the steps of:

checking if there is an equivalence of one of the relevant spectral peaks of the sample with the reference spectral peaks of the reference spectra, and

if an equivalence is detected, correlating the sample spectrum with the spectrum of the reference library around the relevant spectral peak of the sample and the reference spectral peak where the equivalence is detected.

4. The method of comparison of spectra according to claim 3 , wherein:

the step of correlating the sample spectrum with the spectrum of the reference library around the relevant spectral peak of the sample and reference spectral peak is performed within a spectral window, and

the method further comprises the step of, within the spectral window, considering absorbance values of the sample spectrum and of the reference material spectrum during the correlation of the sample spectrum with the reference material's spectrum.

5. The method of comparison of spectra according to claim 3 , wherein, if not detected an equivalence between one of the relevant spectral peaks of the sample and the spectral reference peaks of the reference spectra, the method further comprises the step of correlating a second derivative of the sample spectrum with a second derivative from the reference spectrum library in a dispersion region, the dispersion region obtained from the second derivative of the spectrum in the reference library.

6. A method of comparison of spectra according to claim 5 , wherein the step of correlating the sample spectrum with the reference library spectrum and the step of correlating a second derivative of the sample spectrum with a second derivative of the reference library spectrum are performed through one of the following methods: Pearson correlation formula, cosine similarity and Spearman correlation coefficient.

7. A method of comparison of spectra from the spectrum of a sample and at least one spectrum of a reference library, the method comprising the steps of:

obtaining a second derivative of the sample spectrum and of the spectrum in the reference library, and

correlating the second derivative of the sample spectrum with the second derivative of the reference library spectrum,

wherein the step of correlating the second derivative of the sample spectrum with the second derivative of the reference library spectrum is performed in a dispersion region, the dispersion region being obtained from the second derivative of the reference library spectrum.

8. The method of comparison of spectra according to claim 7 , wherein the dispersion region is determined from calculating at least one dispersion parameter related to the wavelengths of the second derivative of the reference library spectrum, the dispersion parameter related to a dispersion range of the reference library spectrum.

9. The method of comparison of spectra according to claim 8 , wherein, within the dispersion region, consider absorbance values of the second derivative of the sample spectrum and of the second derivative of the reference library spectrum during the correlation of the second derivative of the sample spectrum with the second derivative of the reference library spectrum.

10. A method of comparison of spectra with the identification of a major component of a sample, the method comprising the steps of:

obtaining a spectrum of the sample and of a reference,

previously identifying the major component present in the sample,

correlating the sample spectrum with the reference spectrum, obtaining a first correlation value,

correlating the reference spectrum with a spectrum of the major component, obtaining a second correlation value, and

comparing the first correlation value with the second correlation value.

11. The method of comparison of spectra with the identification of the major component of a sample according to claim 10 , wherein:

the method further comprises the step of defining a dispersion region from a second derivative of the reference spectrum,

the dispersion region is obtained from the calculation of at least one dispersion parameter related to the wavelengths of the second derivative of the reference spectrum, and

the steps to correlate the sample spectrum with the reference spectrum and correlating the reference spectrum with the spectrum of the major component of the sample are carried out within the limits defined by the dispersion region.

12. The method of comparison of spectra with the identification of the major component of a sample according to claim 11 , further comprising the step of subtracting from the value obtained for the correlation between the reference spectrum with the spectrum of the sample, the value obtained in the correlation between the reference spectrum with the spectrum of the major component.

13. The method of comparison of spectra with the identification of the major component of a sample according to claim 12 , further comprising the steps of:

correlating, within the limits defined by the dispersion region, the second derivative of the sample spectrum with the second derivative of the reference spectrum, and

correlating, within the limits defined by the dispersion region, the second derivative of the reference spectrum with the second derivative of the major component spectrum.

14. The method of comparison between spectra with the identification of the major component of a sample according to claim 13 , further comprising the step of subtracting from the value obtained for the correlation between the second derivative of the sample spectrum with the second derivative of the reference spectrum the value obtained from the correlation between the second derivative of the reference spectrum with the second derivative of the spectrum of the major component.