Methods for determining plant rubber content with low field NMR

Patent metadata

Field	Value
Publication number	US-10859650-B2
Application number	US-201715637254-A
Country	US
Kind code	B2
Filing date	Jun 29, 2017
Priority date	Jun 29, 2016
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

Methods are described for quantifying an amount of natural rubber in a plant from a sample of the plant by obtaining a NMR spectrum and analyzing the signal peaks for the natural rubber in the plant sample and a standard component tested in combination with the plant sample. The NMR testing is conducted on a liquid state sample of a solution containing dissolved plant sample and standard component. A pre-determined and known amount of standard component is present in the liquid state sample and provides a reference for calculating an estimated amount of natural rubber in the plant sample. The estimated amount of natural rubber in the sample can be used to quantify the amount of extractable rubber in the sampled plant.

First claim

The invention claimed is:

1. A method for quantifying an amount of natural rubber in a rubber-containing plant by use of low-field NMR, comprising the steps of:
a. introducing a sample solution comprising a sample portion of the plant, a solvent and a known amount of a non-polyisoprene standard rubber into a sample receiving space of a low-field NMR apparatus, and the low-field NMR apparatus operating at a magnetic field strength of 2 T or less for obtaining a NMR spectrum for the sample solution;
b. obtaining a NMR spectrum of the sample solution, the NMR spectrum comprising a first signal peak corresponding to a single proton for the natural rubber present in the portion of the plant, the first signal peak having a first peak area, and a second signal peak corresponding to one or more protons for the non-polyisoprene standard rubber, the second signal peak having a second peak area;
c. quantifying an amount of natural rubber in the portion of the plant by multiplying the first peak area by a conversion factor to obtain an estimate of the number of moles of natural rubber in the plant portion, the conversion factor being the number of moles of the non-polyisoprene standard rubber in the sample solution divided by the second peak area divided by the number of protons corresponding to the second signal peak.

2. The method of claim 1 , further comprising the step of quantifying an amount of natural rubber in the sampled rubber-containing plant by dividing the quantified amount of natural rubber in the portion of the plant by the weight of the portion of the plant to obtain a natural rubber per weight factor and multiplying the natural rubber per weight factor by the total weight of the sampled rubber-containing plant.

3. The method of claim 2 , the plant being guayule and the amount of quantified natural rubber in the sampled rubber-containing plant being the amount of extractable natural rubber contained the guayule plant being tested.

4. The method of claim 1 , further comprising comparing the amount of quantified natural rubber to a pre-determined threshold amount of rubber and making a decision to harvest the rubber-containing plant being tested.

5. The method of claim 1 , further comprising comparing the amount of quantified natural rubber to a pre-determined threshold amount of rubber and making a decision to breed the rubber-containing plant being tested.

6. The method of claim 1 , the method being non-destructive to the plant wherein the portion of the plant used in the sample receiving space of the low-field NMR apparatus to quantify an amount of natural rubber in the plant is less than 5 weight percent of the plant.

7. The method of claim 1 , the low-field NMR apparatus operating at a magnetic field strength of 1.5 T or less for obtaining the NMR spectrum for the sample solution.

8. The method of claim 1 , the low-field NMR apparatus operating at a frequency of 90 MHz less for obtaining the NMR spectrum for the sample solution.

9. The method of claim 1 , the method being performed on the sample solution in less than 10 minutes.

10. The method of claim 1 , the rubber-containing plant being guayule and the non-polyisoprene standard rubber being polybutadiene.

11. The method of claim 1 , the solvent being a deuterated solvent containing an internal standard.

12. The method of claim 10 , the portion of the plant having at least 1 weight percent resin based on the total weight of the portion of the plant in the sample solution introduced into the receiving space of the low-field NMR apparatus.

13. A non-destructive method for quantifying an amount of natural rubber in a guayule plant by use of low-field NMR, comprising the steps of:
a. introducing a sample solution into a sample receiving space of a low-field NMR apparatus, the sample solution consists of a solvent and a dissolved plant sample of the guayule plant, the dissolved plant sample consisting of a dried and ground up portion of the guayule plant, and a pre-determined known amount of moles of a non-polyisoprene standard rubber component, and the low-field NMR apparatus operating at a magnetic field strength of 2 T or less for obtaining a NMR spectrum for the sample solution;
b. obtaining a NMR spectrum for the sample solution, the NMR spectrum comprising a first signal peak corresponding to a single proton position for the natural rubber present in the plant sample of the guayule plant, the first signal peak having a first peak area, and a second signal peak corresponding to one or more protons for the non-polyisoprene standard rubber component, the second signal peak having a second peak area;
c. quantifying the number of moles of the natural rubber in the guayule plant by multiplying the first peak area by a conversion factor to obtain an estimate of the number of moles of natural rubber in the plant sample, the conversion factor being the number of moles of the non-polyisoprene standard rubber component in the sample solution divided by the second peak area divided by the number of protons corresponding to the second signal peak.

14. A non-destructive method for quantifying an amount of natural rubber in a guayule plant by use of low-field NMR, comprising the steps of:
a. introducing a sample solution into a sample receiving space of a low-field NMR apparatus, the sample solution consisting of a solvent and a dissolved plant sample of the guayule plant, the plant sample comprising natural rubber and resin and being a dried and milled portion of the guayule plant, and a pre-determined known amount of moles of a standard high cis 1,4-polybutadiene rubber, and the low-field NMR apparatus operating at a magnetic field strength of 2 T or less for obtaining a NMR spectrum for the sample solution;
b. obtaining a NMR spectrum for the sample solution, the NMR spectrum comprising a first signal peak corresponding to a single proton position for the natural rubber present in the plant sample of the guayule plant, the first signal peak having a first peak area, and a second signal peak corresponding to one or more protons for the standard high cis 1,4-polybutadiene rubber component, the second signal peak having a second peak area;
c. quantifying the number of moles of the natural rubber in the guayule plant by multiplying the first peak area by a conversion factor to obtain an estimate of the number of moles of natural rubber in the plant sample, the conversion factor being the number of moles of the standard high cis 1,4-polybutadiene rubber component in the sample solution divided by the second peak area divided by the number of protons corresponding to the second signal peak, the method being performed on the sample solution in less than 10 minutes.

15. The method of claim 14 , further comprising deciding to harvest the guayule plant by comparing step (c) to a natural rubber harvesting threshold.

16. The method of claim 15 , further comprising extracting the natural rubber from the harvested guayule plant.

17. The method of claim 14 , the portion of the plant having at least 1 weight percent resin based on the total weight of the portion of the plant in the sample solution introduced into the receiving space of the low-field NMR apparatus.

18. The method of claim 14 , the solvent being a deuterated solvent.

19. The method of claim 14 , the method being performed on the sample solution in less than 5 minutes.

Assignees

• Bridgestone Corp

Inventors

• Davis Michael C
• Huang Yingyi

Classifications

• G01R33/4625

  Processing of acquired signals, e.g. elimination of phase errors, baseline fitting, chemometric analysis · CPC title

• G01R33/445

  MR involving a non-standard magnetic field B0, e.g. of low magnitude as in the earth's magnetic field or in nanoTesla spectroscopy, comprising a polarizing magnetic field for pre-polarisation, B0 with a temporal variation of its magnitude or direction such as field cycling of B0 or rotation of the direction of B0, or spatially inhomogeneous B0 like in fringe-field MR or in stray-field imaging · CPC title

• G01N24/08

  by using nuclear magnetic resonance (G01N24/12 takes precedence) · CPC title

• G01R33/465 Primary

  applied to biological material, e.g. in vitro testing · CPC title

• G01R33/4616

  using specific RF pulses or specific modulation schemes, e.g. stochastic excitation, adiabatic RF pulses, composite pulses, binomial pulses, Shinnar-le-Roux pulses, spectrally selective pulses not being used for spatial selection · CPC title