Method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy

Abstract

The invention discloses a method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy, which relates to the technical field of chemical detection and comprises the following steps: weighing a quinalphos internal standard substance and dissolving the quinalphos internal standard substance in deuterated methanol to prepare an internal standard substance solution for later use; the method comprises the following steps: adding a trimethyl phosphate sample into deuterated methanol, respectively preparing solutions with different concentration gradients, adding an internal standard substance solution, respectively measuring integral areas of a measured sample and an internal standard substance, drawing a concentration configuration marking line, and calculating a linear regression equation; the method comprises the following steps: preparing a quinalphos standard solution and a candidate sample solution by using the same solvent and internal standard substance by using a phosphorus spectrum nuclear magnetic quantitative method, carrying out sample introduction analysis on the candidate sample solution, and testing the integral area of trimethyl phosphate and quinalphos; and calculating the content of trimethyl phosphate.

Description

Technical Field

[0001] The invention relates to the technical field of chemical detection, in particular to a detection method for trimethyl phosphate, specifically to a method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy. Background Art

[0002] Trimethyl phosphate, also known as trimethyl phosphate, is a colorless liquid, flammable, easily soluble in water, soluble in ether, and insoluble in ethanol; chemical formula C3H9O4P, molecular weight 140.08, boiling point 197°C, density 1.97g / cm 3 Trimethyl phosphate is an important organic compound and an important intermediate in organic synthesis reactions. It is used to prepare various organic acids, bases, alcohols and other organic substances. It can also be used as a solvent, extractant and gas chromatography stationary liquid for medicines and pesticides.

[0003] In the prior art, since trimethyl phosphate is a genotoxic impurity, it is necessary to strictly control the trimethyl phosphate appearing in the synthesis process of pharmaceutical compounds and in pesticide residues. Therefore, the measurement of trimethyl phosphate is mostly qualitative measurement, and there is little research on quantitative determination. Among them, the quantitative determination uses the peak area normalization method to calculate the purity, which cannot analyze all the impurities contained therein one by one, and the quantitative error of this method may be as high as 20%, affecting the performance evaluation of the product. Summary of the invention

[0004] The invention provides a method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy in order to solve the problem that the current quantitative measurement method of trimethyl phosphate cannot analyze all impurities, resulting in large detection errors and affecting product performance evaluation.

[0005] The present invention is implemented by the following technology: The present invention provides a method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy, comprising the following steps: a. Preparation of internal standard solution Weigh quinalphos internal standard and dissolve it in deuterated methanol to prepare a 5.0 mg / mL internal standard solution for later use. Select quinalphos as the internal standard, as the phosphorus spectrum peak has a good shape and is well separated from the sample quantitative peak without causing interference. Further, 200.0 mg of quinalphos internal standard was weighed and dissolved in 40.000 mL of deuterated methanol to prepare a 5.0 mg / mL internal standard solution for later use.

[0006] b. Preparation of standard solution Take a trimethyl phosphate sample and add it to deuterated methanol, prepare solutions with different concentration gradients, and add 100 uL of the internal standard solution; specifically, take a trimethyl phosphate sample and add it to 1 mL of deuterated methanol to prepare solutions with concentrations of 10.0 mg / mL, 20.0 mg / mL, 40.0 mg / mL, 60.0 mg / mL, 80.0 mg / mL, and 100 mg / mL, respectively; Add 100 uL of internal standard solution and transfer to the NMR tube. Measure the integrated area of ​​the sample and the internal standard respectively, draw the concentration configuration line, and calculate the linear regression equation and fit.

[0007] c. Quantitative measurement Since the hydrogen spectrum is narrow and has severe peak overlap, while the phosphorus spectrum is wide and has simple peak extraction, the phosphorus spectrum method was chosen for quantification.

[0008] Phosphorus NMR quantitative method ( 31 P-qNMR), fixed power 40 W, optimized 90° pulse width 14.8 μs, relaxation delay time D1 30 s, scan number NS 64 times, to ensure the straightness of the baseline and high signal-to-noise ratio, sampling time AQ 3 s; Using deuterated methanol as solvent and quinalphos purity standard substance as internal standard, prepare quinalphos standard solution and candidate sample solution, take candidate sample solution for injection analysis, and test the integrated area of ​​trimethyl phosphate I 磷酸三甲酯 and the integrated area of ​​quinalphos I 喹硫磷 , measure three times in parallel, take the average value, and quantify the content of impurity peak by accurate integration; d, calculate the content of trimethyl phosphate The content of trimethyl phosphate in the candidate sample is calculated according to Formula 1, Formula 1 Where: w is the impurity peak content in the sample to be tested, expressed in percentage; A1 and A2 are the integrated areas of the sample and internal standard respectively; m1 and m2 are the weights of the sample to be tested and the internal standard respectively; M1, M2 molar mass of the sample and internal standard; K is the purity of the internal standard.

[0009] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy. A quinalphos purity standard substance is used as an internal standard, and the content of the trimethyl phosphate in a sample is calculated by testing the integral area of ​​the trimethyl phosphate and the integral area of ​​the quinalphos, so as to accurately measure the content of the trimethyl phosphate. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A concentration configuration line graph for an embodiment of the present invention.

[0011] Figure 2 These are the splitting spectra of samples of different concentrations in the sample quantity selection of the present invention.

[0012] Figure 3 This is a comparative spectrum of different experimental methods in the pulse experimental method selection of the present invention.

[0013] Figure 4 NMR spectrum of the solvent selected in the present invention.

[0014] Figure 5 It is the fitting curve of T1 time in the relaxation time T1 test of the present invention.

[0015] Figure 6 The scanning number NS of the present invention optimizes the hydrogen spectrum comparison spectrum of different scanning numbers.

[0016] Figure 7 This is a comparison spectrum of hydrogen spectra at different D1 times in the optimization of the relaxation delay time D1 of the present invention.

[0017] Figure 8 This is a comparison of hydrogen spectra at different sampling times in the sampling time AQ optimization of the present invention.

[0018] Fig. 9 This is a comparison spectrum of the hydrogen spectra of trimethyl phosphate and DMMP in the component verification of the present invention.

[0019] Fig.10 This is a carbon spectrum comparison chart of trimethyl phosphate and DMMP in the component verification of the present invention.

[0020] Fig.11 This is a comparison chart of the phosphorus spectra of trimethyl phosphate and DMMP in the component verification of the present invention.

[0021] Fig.12 This is a comparison chart of the phosphorus spectra of the zgig and ASSURE_31P methods selected for the pulse experimental method of the present invention.

[0022] Fig.13 This is a comparison spectrum of phosphorus spectra under different scanning times in the pulse experimental method of the present invention.

[0023] Fig.14It is the 31P chemical shift under different relaxation delay times in the optimization of relaxation delay time D1 of the present invention.

[0024] Fig.15 The figure is a comparison spectrum of the phosphorus spectra of quinalphos and DMMP in the selection of the internal standard of the present invention. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are described below in conjunction with the accompanying drawings.

[0026] one, 1 Optimization of H-qNMR test conditions 1.1 Sample volume selection The fixed sample solvent is CDCl3, the solvent volume is 600 μL, and 30 μL, 50 μL and 100 μL of the sample are taken into the NMR tube with a pipette, and samples of different concentrations are prepared and shaken for use. The comparison spectra of hydrogen spectra of different concentrations obtained by the test are shown in Table 1. Figure 2 shown.

[0027]

[0028] It can be seen that with the increase of concentration, the peak splitting at the chemical shift δ=3.68 ppm becomes significantly worse, so the quantitative sample volume of 30 μL is determined to be the best.

[0029] 1.2 Pulse experiment method selection Use a pipette to transfer 30 μL of sample into the NMR tube, add 600 μL of CDCl3 solution, shake well and set aside. The number of scans NS was fixed to 16 times, and the hydrogen spectrum was tested using different experimental methods. The comparison spectra of the three experimental methods (PROTON red, zg green, ASSURE_1H blue) are shown in the figure below. Figure 3 shown.

[0030] From the hydrogen spectrum comparison, it can be seen that the signal-to-noise ratio of the hydrogen spectrum chemical shift obtained by the ASSURE_1H experimental method is best at δ=3.68 ppm, so the ASSURE_1H experimental method is selected for hydrogen spectrum quantification.

[0031] 1.3 Solvent selection Take 30 μL of sample in two NMR tubes, add 600 μL CDCl3 (deuterated chloroform) and 600 μL MeOD (deuterated methanol) to prepare the solution, and test it with PROTON method. The scanning number is NS=32 and the spectrum is as follows: Figure 4 shown.

[0032] By comparison, it was found that the solutions of the samples dissolved in chloroform and methanol were all transparent solutions. In addition, except for the residual solvent peak of deuterated chloroform at 7.26 ppm, the residual solvent peak of deuterated methanol at 3.31 ppm, and the water peak at 4.82 ppm in the NMR spectrum, the other main peaks were the same as the impurity peaks, so chloroform and methanol could both be used as quantitative solvents, and methanol with a smaller residual solvent peak was preferred.

[0033] 1.4 Relaxation time T1 test Take 30 μL of sample into the NMR tube, add 600 μL of CDCl3 solution, shake well and test T1 time. The fitting curve of T1 time is as follows: Figure 5 shown.

[0034] According to the T1 test results, T1=3.283 s at a chemical shift of δ3.681 ppm and T1=2.638 s at a chemical shift of δ1.423 ppm. In order to ensure the accuracy of quantitative analysis, the D1 time is usually set to be greater than 5 times the T1 time, so the D1 time is set to 15 s in the experiment.

[0035] 1.5 Scan times NS optimization Using the ASSURE_1H experimental method, the D1 time was fixed at 15 s, and the number of scans NS was set to 8, 16, 32, 64, and 128 times, respectively, and the hydrogen spectra were collected. The hydrogen spectra of different scan times were compared as shown in the figure. Figure 6 shown.

[0036] By comparing the NMR spectra at different scanning times and the signal-to-noise ratio at the chemical shift δ3.68 ppm, it was finally determined that the optimal scanning number was 32 times.

[0037] 1.6 Optimization of relaxation delay time D1 Using the ASSURE_1H experimental method, the number of scans NS was fixed to 32 times, and the D1 time was set to 5 s, 10 s, 15 s, 20 s and 25 s respectively. The hydrogen spectra were collected and the hydrogen spectra with different D1 times were compared as shown in the figure. Figure 7 shown.

[0038] From the hydrogen spectrum comparison, it can be seen that when D1=10 s, the peak signal at the chemical shift δ=3.68 ppm is the strongest and the signal-to-noise ratio is the best, so the D1 time is determined to be 10 s.

[0039] 1.7 Sampling time AQ optimization Using the ASSURE_1H experimental method, the number of scans NS was fixed to 32 times, the D1 time was 10 s, and the AQ time was set to 1.5 s, 3 s, 4 s, 5 s, and 6 s, respectively, to collect hydrogen spectra. The hydrogen spectra obtained by testing at different AQ times are shown in the figure below. Figure 8 shown.

[0040] From the hydrogen spectrum comparison, it can be seen that the peak intensity at the chemical shift δ=3.68 ppm is similar. By calculating the signal-to-noise ratio intensity, the AQ time is determined to be 3 s.

[0041] In summary, the experimental conditions for the quantitative analysis of candidate samples by hydrogen spectrum were preliminarily determined as follows: deuterated chloroform as solvent, sample volume of 30 μL, ASSURE_1H experimental method, D1 time of 10 s, AQ time of 3 s, and scan times of 32 times.

[0042] 2. Determination of the conditions for quantitative hydrogen spectrum testing Through the above experiments, the experimental conditions for the quantitative analysis of candidate samples by hydrogen spectrum were determined as follows: deuterated chloroform was used as the solvent, the sample volume was 30 μL, the ASSURE_1H experimental method was selected, the D1 time was 10 s, the AQ time was 3 s, and the number of scans was 32 times.

[0043] 2.1 Ingredient Verification Take 30 μL of trimethyl phosphate sample and dissolve it in 600 μL CDCl3, shake it well and set aside for use, test the hydrogen spectrum, and compare it with the hydrogen spectrum of the candidate. From the comparison chart, it can be seen that the hydrogen spectrum is narrow and the peaks overlap seriously, and it is impossible to determine whether there is trimethyl phosphate. Further test the carbon spectrum and phosphorus spectrum.

[0044] Take 100 μL of sample and 100 μL of trimethyl phosphate sample, dissolve them in 600 μL of CDCl3 and shake well, test the carbon spectrum and phosphorus spectrum, the scanning times NS are 1024 and 128 respectively. Fig. 9 , 10 , as shown in 11.

[0045] from Fig.10 It can be seen that the chemical shift δ = 54.29 ppm, the methyl carbon peak in trimethyl phosphate, has a peak at the corresponding chemical shift in the DMMP candidate C13CPD spectrum. Fig.11 It can be seen that the characteristic peak of the phosphorus spectrum of trimethyl phosphate is at a chemical shift of 2 ppm, and it also has a peak at the corresponding position in the phosphorus spectrum of the DMMP candidate. Therefore, combining the carbon spectrum and the phosphorus spectrum, it is determined that the DMMP candidate contains trimethyl phosphate, an organic impurity, which is consistent with the qualitative analysis results of GC-MS. At the same time, it can be seen that the spectrum width range of the carbon spectrum and the phosphorus spectrum is relatively large, and the peak of the phosphorus spectrum is simpler than that of the carbon spectrum.

[0046] Since the hydrogen spectrum is narrow and the peaks overlap seriously, and the phosphorus spectrum has a wide range and simple peaks, the phosphorus spectrum nuclear magnetic resonance quantitative method ( 31 P-qNMR) to further optimize the quantitative testing conditions of phosphorus spectrum.

[0047] three, 31 Optimization of P-qNMR test conditions 3.1 Solvent selection according to 1 The test results of solvent selection in H-qNMR test conditions show that both chloroform and methanol can be used as quantitative solvents, and methanol is preferred. Methanol is a commonly used solvent for nuclear magnetic resonance. Candidate samples have good solubility in methanol, and the solvent does not contain phosphorus and has no interference with quantification. Therefore, deuterated methanol is proposed to be used as the quantitative solvent.

[0048] 3.2 Pulse experiment method selection Take 30 μL of the candidate and dissolve it in 600 μL of deuterated methanol and shake it well. Use zgig and ASSURE_31P methods to test the phosphorus spectrum respectively. The scanning number NS is 128 times. The comparison of the phosphorus spectra obtained by the two methods is shown in the figure below. Fig.12 shown.

[0049] The signal-to-noise ratios of the main peak at the chemical shift of 35.58 ppm in the ASSURE_31P and zgig methods were 23158.76 and 10714.26, respectively. The main peak signal-to-noise ratio of the ASSURE_31P method was better, so the ASSURE_31P method was determined to be used for quantification. The 90° pulse of the candidate was further calibrated by the ASSURE_31P experimental method, and the 90° pulse width after optimization with a fixed power of 40 W was 14.8μs.

[0050] 3.3 Scan times NS optimization Take 100 μL of DMMP candidate and dissolve it in 600 μL of deuterated methanol and shake it well. Use ASSURE_31P method to test the phosphorus spectrum. The scanning times NS are 16, 32, 64, 128 and 256 times respectively. The phosphorus spectra of different scanning times are compared as shown in the following figure. Fig.13 shown.

[0051] Comparing the phosphorus spectrum, it can be seen that as the number of scans increases, the signal-to-noise ratio gradually increases, the scanning time also gradually increases, and when the number of scans is 128 and 256, the test time reaches 1.25 h and 2.5 h respectively, and the baseline is also partially distorted. Therefore, the optimal number of scans is 64, considering the signal-to-noise ratio, scanning time and spectrum baseline processing.

[0052] 3.4 Optimization of relaxation delay time D1 Take 100 μL of DMMP candidate and dissolve it in 600 μL of deuterated methanol and shake it well. Use ASSURE_31P method to test the phosphorus spectrum. The number of scans NS is fixed to 64 times, and D1 is set to 20 s, 30 s, 35 s, 40 s and 45 s respectively.

[0053] like Fig.14As shown in the figure, by comparing the phosphorus spectrum, it can be seen that there is basically no difference in the signal-to-noise ratio when D1 is above 30 s. As D1 increases, the scanning time gradually increases. Therefore, D1 is selected as 30 s.

[0054] 3.5 Selection of internal standard The prior art shows that the qNMR method can use national purity standard substances such as benzoic acid, ethylparaben, potassium hydrogen phthalate, dimethyl sulfoxide, etc. as internal standards. When optimizing the test conditions of hydrogen spectrum nuclear magnetic resonance, the present invention selected two standard substances, the benchmark benzoic acid purity (acidity) standard substance and the food preservative ethylparaben. After testing, both can be used as internal standards. 1 H-qNMR internal standard. However, since the above two are not suitable as internal standards for phosphorus spectrum, they are no longer used. After investigating phosphorus-containing standards, it is planned to use the national purity standard quinalphos purity standard material for experimental verification.

[0055] Weigh 5 mg of the internal standard quinalphos, dissolve it in 600 μL of deuterated methanol and shake well. Use the ASSURE_31P method with a scan number NS of 128 to obtain the internal standard phosphorus spectrum.

[0056] like Fig.15 As shown, the quantitative peak of the internal standard quinalphos is a single peak, the peak shape of the phosphorus spectrum is good, and it is completely separated from the DMMP peak, without interference from other impurities. Therefore, quinalphos was determined as the internal standard for phosphorus spectrum nuclear magnetic resonance determination. Its parameters are as follows: Quinalphos purity standard substance, standard value 99.8%, expanded uncertainty 0.2% ( k =2).

[0057] In summary, the quantitative test conditions for phosphorus spectrum of candidate samples were determined as follows: the solvent was deuterated methanol, the internal standard was quinalphos purity standard substance, the ASSURE_1H experimental method was selected, the relaxation delay time D1 was 30 s, the number of scans NS was 64 times, and the sampling time AQ was 3 s.

[0058] The invention discloses a method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy, the accuracy of which can reach or approach the level of HPLC. The most widely used hydrogen spectrum quantitative nuclear magnetic resonance method ( 1 H-qNMR), including the following steps: a. Preparation of internal standard solution Accurately weigh 200.0 mg of quinalphos internal standard and dissolve it in 40.000 mL of deuterated methanol to prepare a 5.0 mg / mL internal standard solution for later use.

[0059] b. Preparation of standard solution Take trimethyl phosphate sample and add it to 1 mL of deuterated methanol to prepare solutions with concentrations of 10.0 mg / mL, 20.0 mg / mL, 40.0 mg / mL, 60.0 mg / mL, 80.0 mg / mL, and 100 mg / mL, respectively. Add 100 uL of internal standard solution and transfer to NMR tubes. Measure the integrated areas of the sample and internal standard, respectively, and draw concentration configuration lines as shown in the figure. Figure 1 As shown, the linear regression equation is calculated as y=1.8107x+0.4853, and the fitting degree R 2 =0.9969.

[0060] c. Quantitative measurement Phosphorus NMR quantitative method ( 31 P-qNMR), fixed power 40 W, optimized 90° pulse width 14.8 μs, relaxation delay time D1 30 s, scan number NS 64 times, to ensure the straightness of the baseline and high signal-to-noise ratio, sampling time AQ 3 s; Using deuterated methanol as solvent and quinalphos purity standard substance as internal standard, prepare quinalphos standard solution and candidate sample solution, take 200 μL candidate sample and weigh accurately m 样品 (about 220 mg), add to 300 μL of deuterated methanol, add 60 μL of 5.0 mg / mL quinalphos standard solution (the mass of quinalphos in the sample solution is m 喹硫磷 =0.3 mg) and transferred to an NMR tube with a total volume of 560 μL.

[0061] After the instrument parameters are stable, take the candidate sample solution for analysis and test the integrated area of ​​trimethyl phosphate. I 磷酸三甲酯 and the integrated area of ​​quinalphos I 喹硫磷 , parallel determination was performed three times, the average value was taken, and the content of the impurity peak was quantified by integration; d, calculate the content of trimethyl phosphate The content of trimethyl phosphate in the candidate sample is calculated according to formula 2: Formula 2 Where: P NMR is the organic impurity content measured by nuclear magnetic resonance method; I 有机杂质 Assign integrated areas to peaks for organic impurities; I std Assign the integrated area of ​​the peak to the internal standard; nst The number of nuclei in the nucleus group of the specified peak for the internal standard; n 有机杂质 The number of nuclei in the nucleus group of the specified peak for organic impurities; M 有机杂质 is the molecular weight of the organic impurity; m std is the mass of the added internal standard; m 有机杂质 is the sample weight of the organic impurity sample; P std is the purity of the internal standard.

[0062] According to the molecular weight of the internal standard quinalphos is 298.30, the purity is 99.8%, the molecular weight of the organic impurity trimethyl phosphate is 140.08, and the number of nuclei in the nucleus group of the internal standard quinalphos and the organic impurity trimethyl phosphate is the same, the phosphorus spectrum nuclear magnetic quantitative calculation formula of the organic impurity trimethyl phosphate is as follows: Formula 3 Where: P NMR is the content of organic impurity trimethyl phosphate measured by phosphorus spectrum nuclear magnetic resonance method; I 磷酸三甲酯 The integrated area of ​​the peak designated for trimethyl phosphate, an organic impurity in the sample; I 喹硫磷 The integrated area of ​​the peak designated as internal standard quinalphos in the sample; m 喹硫磷 is the mass of the added internal standard quinalphos; m 候选物 is the sample weight of the candidate sample; GC-MS was used to determine the content of trimethyl phosphate, an organic impurity in the candidate standard substance. After calculation, the results were as follows: Table 2 GC-MS determination data of trimethyl phosphate content of candidate substances

[0063] The result is the overall average:

[0064] according to 31 The P-qNMR organic impurity determination method was used to determine the content of trimethyl phosphate, an organic impurity, in the candidate standard substance. After calculation, the results are as follows: Table 3 Content of Trimethyl Phosphate in Candidates 31 P-qNMR determination data

[0065] The result is the overall average:

[0066] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various deformations and changes. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy, characterized in that: The following steps are involved: a. Preparation of internal standard solution Weigh quinalphos internal standard and dissolve it in deuterated methanol to prepare a 5.0 mg / mL internal standard solution for later use; b. Preparation of standard solution Take a trimethyl phosphate sample and add it to deuterated methanol, prepare solutions with different concentration gradients, add 100 uL of the internal standard solution, measure the integrated area of ​​the sample and the internal standard, draw the concentration configuration line, and calculate the linear regression equation; c. Quantitative measurement The phosphorus spectrum nuclear magnetic quantitative method was selected, deuterated methanol was used as the solvent, and the purity standard substance of quinalphos was used as the internal standard. The quinalphos standard solution and the candidate sample solution were prepared, and the candidate sample solution was sampled and analyzed to test the integrated area of ​​trimethyl phosphate. I 磷酸三甲酯 and the integrated area of ​​quinalphos I 喹硫磷 , the test was performed three times in parallel and the average value was taken; d, calculate the content of trimethyl phosphate The content of trimethyl phosphate in the candidate sample is calculated according to formula 1, Formula 1 Where: w is the impurity peak content in the sample to be tested, expressed in percentage; A1 and A2 are the integrated areas of the sample and internal standard respectively; m1 and m2 are the weights of the sample to be tested and the internal standard respectively; M1, M2 molar mass of the sample and internal standard; K is the purity of the internal standard.

2. A method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy according to claim 1, characterized in that: In step c, in the phosphorus spectrum nuclear magnetic resonance quantitative method, the optimized 90° pulse width at a fixed power of 40 W is 14.8 μs, the relaxation delay time D1 is 30 s, the number of scans NS is 64 times, and the sampling time AQ is 3 s.

3. A method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy according to claim 1, characterized in that: Step a includes the following steps: Weigh 200.0 mg of quinalphos internal standard and dissolve it in 40.000 mL of deuterated methanol to prepare a 5.0 mg / mL internal standard solution for later use.

4. A method for quantitatively testing trimethyl phosphate by nuclear magnetic resonance spectroscopy according to claim 1, characterized in that: Step b comprises the following steps: Take trimethyl phosphate sample and add it to 1 mL of deuterated methanol to prepare solutions with concentrations of 10.0 mg / mL, 20.0 mg / mL, 40.0 mg / mL, 60.0 mg / mL, 80.0 mg / mL, and 100 mg / mL, respectively. Add 100 uL of internal standard solution and transfer them to NMR tubes. Measure the integrated areas of the sample and internal standard, draw concentration configuration lines, and calculate the linear regression equation.

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