Quantitative analysis method for content of LLM-105 and PYX in composite explosive

Abstract

The invention discloses a quantitative analysis method for the content of LLM-105 and PYX in a mixed explosive, which combines a 1H spectrum quantitative nuclear magnetic resonance technology and a peak-dividing fitting technology, performs peak-dividing fitting on a quantitative 1H spectrum specific region of a sample through a Gaussian / Lorentz model, and obtains the peak area of an LLM-105 characteristic group-NH2 and the peak area of a PYX characteristic group-C = CH-. And comparing the peak area caused by protons on the characteristic groups of the LLM-105 and PYX components with the peak area caused by protons on-CH groups in an internal standard substance tetrachloroethane to obtain the absolute content of the LLM-105 and PYX components in the composite explosive. The detection method does not need a separation step, the sample pretreatment is simple, convenient and rapid, and the detection sensitivity and the accuracy are high.

Description

Technical Field

[0001] The present invention belongs to the technical field of energetic materials, and relates to a quantitative analysis method for the contents of LLM-105 and PYX in a mixed explosive. Background Art

[0002] A mixed explosive is an energy material for ammunition to damage targets and is the main factor determining the power of conventional weapons. It has extensive applications in both military equipment and civilian industries. Currently, mixed explosives worldwide are developing towards higher energy and greater safety, and heat-resistant explosives have attracted much attention due to their characteristics of high energy and low sensitivity. LLM-105 (1-oxo-2,6-diamino-3,5-dinitropyrazine, C4H4N6O5) and PYX (2,6-bis(picrylamino)-3,5-dinitropyridine, C 16 H6N 12 O 12 ) are two single-component heat-resistant explosives with relatively good comprehensive properties among current high-energy and low-sensitivity energetic materials. As the basic components of heat-resistant mixed explosives, they are often used in the manufacture of ultra-high-temperature perforating charges and have been widely used in aerospace and underground exploration and development.

[0003] Quantitative analysis of each component in a heat-resistant mixed explosive is the key to ensuring product quality and the technical support for product inspection and testing. Quantitative analysis of components in a mixed explosive usually adopts the method of dissolution, separation, drying, and then obtaining the mass difference, and its principle is the mass difference subtraction method. LLM-105 and PYX have a nitrogen-benzene heterocyclic polynitro structure, and their dissolution properties are very similar. Common solvents are difficult to completely separate the two and accurately quantify them, which will lead to a situation where the measured content does not conform to the actual process, and it is not conducive to accurately reflecting the product quality situation. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a quantitative analysis method for the contents of LLM-105 and PYX in a mixed explosive, and to solve the problems in the prior art that due to the very similar dissolution properties of LLM-105 and PYX, common solvents are difficult to completely separate the two and accurately quantify them, resulting in a situation where the measured content does not conform to the actual process, and it is not conducive to accurately reflecting the product quality situation, etc.

[0005] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0006] A quantitative analysis method for the contents of LLM-105 and PYX in a mixed explosive, which uses high-resolution superconducting nuclear magnetic 1The chemical shifts of characteristic groups of the samples LLM-105 and PYX components were obtained by quantitative nuclear magnetic resonance technology of H spectrum. Peak fitting was carried out through the Gaussian / Lorentz model of the peak fitting model. At the same time, tetrachloroethane / carbon tetrachloride was used as the internal standard substance. By comparing the peak area caused by the protons on the characteristic groups of LLM-105 and PYX components with the peak area caused by the protons on the -CH group in the internal standard substance, the absolute contents of the two components of LLM-105 and PYX in the mixed explosive were obtained, and the accurate analysis of the contents of LLM-105 and PYX components in the mixed explosive was realized.

[0007] The present invention further includes the following technical features:

[0008] Specifically, it includes the following steps:

[0009] S1, preparation of the internal standard solution of tetrachloroethane / carbon tetrachloride as the internal standard substance: Weigh m b g of carbon tetrachloride into a dry volumetric flask, and then add m a g of tetrachloroethane, shake well, and use it as the internal standard solution;

[0010] S2, sample preparation: Weigh m1 mg of the sample into a nuclear magnetic tube, add deuterated dimethyl sulfoxide solvent, and ultrasonically assist to fully dissolve the sample; Add about m0 mg of the prepared tetrachloroethane / carbon tetrachloride internal standard solution to the dissolved sample, shake well, and use it for nuclear magnetic resonance testing;

[0011] S3, sample analysis: Set the test conditions of the high-resolution superconducting nuclear magnetic resonance spectrometer, select the single-pulse sequence, and collect the sample 1 1H nuclear magnetic spectrum, set the relaxation delay time to ≥10 s, and set the number of scans to ≥128 times; Put the nuclear magnetic tube filled with the prepared sample into the superconducting nuclear magnetic, and conduct sample detection;

[0012] S4, calculation of the contents of LLM-105 and PYX components: Since there is partial overlap in the characteristic signals of the characteristic groups -NH2 of LLM-105 and -C=CH- of PYX, use peak fitting software to perform peak fitting processing on the signals, and select the Gaussian / Lorentz mode; Finally, compare the peak areas caused by the protons on the characteristic groups of LLM-105 and PYX with the peak area caused by the protons on the -CH group in the internal standard substance tetrachloroethane, and calculate the percentage contents of LLM-105 and PYX.

[0013] Specifically, the percentage contents of LLM-105 and PYX are calculated according to formulas (1) and (2):

[0014]

[0015] In the formula:

[0016] W1 — Percentage content of LLM-105, %;

[0017] W2 — Percentage content of PYX, %;

[0018] h1 — Peak area of the 1H NMR spectrum of LLM-105 1 ;

[0019] h2 — Peak area of the 1H NMR spectrum of PYX 1 ;

[0020] h s — Peak area of the 1H NMR spectrum of tetrachloroethane 1 ;

[0021] n1 — Number of H atoms in the -NH2 structure in LLM-105, 4;

[0022] n2 — Number of H atoms in the -C=CH- structure in PYX, 5;

[0023] n s — Number of H atoms in the -CH structure in tetrachloroethane, 2;

[0024] M1 — Relative molecular mass of LLM-105, 216 g / mol;

[0025] M2 — Relative molecular mass of PYX, 621 g / mol;

[0026] M s — Relative molecular mass of tetrachloroethane, 168 g / mol;

[0027] m a — Mass of weighed tetrachloroethane, g;

[0028] m b — Mass of weighed carbon tetrachloride, g;

[0029] m0 — Mass of weighed internal standard solution, mg;

[0030] m1 — Mass of weighed sample, mg;

[0031] Each sample is determined in parallel for six groups, and the relative standard deviation of the parallel results is not more than 2%. The result is taken as its arithmetic mean and expressed to two decimal places.

[0032] Compared with the prior art, the present invention has the following technical effects:

[0033] In the method of the present invention, high-resolution superconducting nuclear magnetic 1 1H NMR quantitative nuclear magnetic resonance technology is used to obtain the chemical shifts of characteristic groups of LLM-105 and PYX components. The characteristic group in LLM-105 is -NH2 ( 1The chemical shifts of the H spectrum are 8.77 and 9.05 ppm), and the characteristic group in PYX is -C=CH-( 1 The chemical shifts of the H spectrum are 8.86 and 9.12 ppm), and peak fitting is performed through the Gaussian / Lorentz model. At the same time, tetrachloroethane / carbon tetrachloride is used as the internal standard substance (the characteristic group is -CH, and the chemical shift is 6.94 ppm). According to the comparison between the peak areas or peak heights caused by the protons on the characteristic groups of LLM-105 and PYX components and the peak area caused by the protons on the -CH group in the internal standard substance tetrachloroethane, the absolute contents of the two components of LLM-105 and PYX in the mixed explosive are obtained; this method has the advantages of simple test operation, high sensitivity, and high accuracy. Description of the Drawings

[0034] Figure 1 They are the molecular structure diagrams of LLM-105 and PYX.

[0035] Figure 2 They are the 1 Comparison diagrams of the H nuclear magnetic spectrum (left) of pure components of LLM-105 and PYX and a certain mixed explosive A and the enlarged area of 8 - 10 ppm (right).

[0036] Figure 3 They are the peak area fitting diagrams of the characteristic groups of LLM-105 and PYX in a certain mixed explosive A. Detailed Embodiment

[0037] The present invention provides a quantitative analysis method for the contents of LLM-105 and PYX in a mixed explosive. LLM-105 and PYX are single-component heat-resistant explosives with a nitrogen-benzene heterocyclic polynitro structure and are important components of the mixed explosive. Due to their very similar solubility properties, common solvents are difficult to completely separate the two and accurately quantify them, which will lead to a situation where the measured content does not conform to the actual process, and it is not conducive to accurately reflecting the product quality. Quantitative nuclear magnetic resonance (qNMR) technology, as a detection technology with high precision and accuracy, can accurately distinguish different structures and components through different chemical environments of atomic nuclei. Using the principle that its resonance peak area or peak height is directly proportional to the content of the component to be measured, by comparing the peak area or peak height caused by the protons on the specific group of the component to be measured with the peak area or peak height caused by the protons on a certain specified group in the reference standard, the absolute content of the component to be measured can be obtained to achieve quantitative analysis. At present, this method has been widely used in fields such as food, medicine, chemistry, and agriculture. Compared with the commonly used mass difference subtraction method, the quantitative nuclear magnetic resonance technology does not require a separation step, the sample pretreatment step is simple, fast, and the detection efficiency is high, which is an effective means for quantitative analysis of the contents of multiple components.

[0038] In order to accurately obtain the absolute contents of LLM-105 and PYX in the composite explosive, there are two key factors. One is the selection of specific groups of LLM-105 and PYX components, which requires significant differences in their chemical shifts and independent peak shapes in the nuclear magnetic 1 1H spectrum; the other is the use of an internal standard, which is very important. It can eliminate the influence of factors such as the volume, concentration, and signal intensity of the sample, and improve the accuracy of analysis. The internal standard is required to have good chemical stability with the sample to be measured to ensure that no chemical reactions or degradation occur during the experiment. In addition, the chemical shift value of the internal standard is required to have an obvious difference from that of the sample to be measured and not affect the peak area of the sample to be measured. The chemical structures of LLM-105 and PYX are as Figure 1 shown, and the 1 differences in the chemical shift values of their 1H spectra are small and cannot present independent peak shapes, which brings difficulties to the quantitative analysis of the two.

[0039] The method of the present invention uses high-resolution superconducting nuclear magnetic 1 1H spectrum quantitative nuclear magnetic resonance technology to obtain the chemical shifts of characteristic groups of LLM-105 and PYX components in the sample. Peak fitting is performed through the Gaussian / Lorentz model of the peak fitting model. At the same time, 1,1,2,2-tetrachloroethane / carbon tetrachloride is used as the internal standard substance, and its chemical shift value has an obvious difference from the characteristic shift values of LLM-105 and PYX, and it is an inert component. According to the comparison between the peak area or peak height caused by protons on the characteristic groups of LLM-105 and PYX components and the peak area caused by protons on the -CH group in the internal standard substance 1,1,2,2-tetrachloroethane, the absolute contents of LLM-105 and PYX in the composite explosive are obtained, and the accurate analysis of the contents of LLM-105 and PYX components in the composite explosive is realized.

[0040] Specifically, a high-resolution superconducting nuclear magnetic resonance spectrometer is selected as the test instrument, and the field strength is required to be 800 MHz or above. The fitting software for peak fitting includes dmfit, MestReNova, Origin, etc. The chemical shift of the specific region for peak fitting is 8.5-9.3 ppm.

[0041] The principle of the test method is: through the Gaussian / Lorentz model, peak fitting is performed on the specific region of the quantitative 1 1H spectrum of the sample to obtain the peak area of the -NH2 group of the LLM-105 characteristic group and the peak area of the -C=CH- group of the PYX characteristic group. According to the comparison between the peak areas caused by protons on the characteristic groups of LLM-105 and PYX components and the peak area caused by protons on the -CH group in the internal standard substance 1,1,2,2-tetrachloroethane, the absolute contents of LLM-105 and PYX in the composite explosive are obtained.

[0042] The method of the present invention specifically includes the following steps:

[0043] S1, Preparation of the internal standard substance, tetrachloroethane / carbon tetrachloride internal standard solution: Weigh approximately a certain amount of carbon tetrachloride, m b g (analytical grade) into a clean and dry volumetric flask, and then add m a g of tetrachloroethane (analytical grade), cover the cap, and shake well to use as the internal standard solution;

[0044] S2, Sample preparation: Weigh m1 mg (accurate to 0.1 mg) of the sample into a nuclear magnetic resonance tube, add a tube of deuterated dimethyl sulfoxide solvent (about 0.6 mL), cover the cap, and ultrasonically assist to fully dissolve the sample; Add approximately m0 mg (accurate to 0.1 mg) of the prepared tetrachloroethane / carbon tetrachloride internal standard solution to the dissolved sample, shake well, and use for nuclear magnetic resonance testing; The sample is a mixed material containing both LLM-105 and PYX, two single-component heat-resistant explosives;

[0045] S3, Sample analysis: Set the test conditions of the high-resolution superconducting nuclear magnetic resonance spectrometer, select the single-pulse sequence, and collect the 1 1H nuclear magnetic resonance spectrum of the sample. Set the relaxation delay time to ≥10 s and the number of scans to ≥128 times. Place the nuclear magnetic resonance tube containing the prepared sample into the superconducting nuclear magnetic resonance instrument for sample detection;

[0046] S4, Calculation of the contents of LLM-105 and PYX components: Since there is partial overlap in the characteristic signals of the characteristic groups -NH2 of LLM-105 and -C=CH- of PYX, use a peak separation software to perform peak separation fitting on the signals, and select the Gaussian / Lorentz mode; Finally, perform quantification through the ratio of the peak areas of LLM-105, PYX, and the internal standard tetrachloroethane.

[0047] The percentage contents of LLM-105 and PYX are calculated according to formulas (1) and (2):

[0048]

[0049] In the formulas:

[0050] W1 - The percentage content of LLM-105, %;

[0051] W2 - The percentage content of PYX, %;

[0052] h1 - The peak area of the 1H nuclear magnetic resonance spectrum of LLM-105 1 of the sample;

[0053] h2 - The peak area of the 1H nuclear magnetic resonance spectrum of PYX 1 of the sample;

[0054] h s - The peak area of the 1H nuclear magnetic resonance spectrum of tetrachloroethane 1 of the sample;

[0055] n1 —— The number of H atoms in the -NH2 structure in LLM-105, 4;

[0056] n2 —— The number of H atoms in the -C=CH- structure in PYX, 5;

[0057] n s —— The number of H atoms in the -CH structure in tetrachloroethane, 2;

[0058] M1 —— The relative molecular mass of LLM-105, 216 g / mol;

[0059] M2 —— The relative molecular mass of PYX, 621 g / mol;

[0060] M s —— The relative molecular mass of tetrachloroethane, 168 g / mol;

[0061] m a —— The mass of tetrachloroethane weighed, g;

[0062] m b —— The mass of carbon tetrachloride weighed, g;

[0063] m0 —— The mass of the internal standard solution weighed, mg;

[0064] m1 —— The mass of the test sample weighed, mg;

[0065] Each test sample is determined in parallel for six groups, and the relative standard deviation of the parallel results is not more than 2%. The results are taken as their arithmetic mean and expressed to two decimal places.

[0066] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solutions of this application fall within the protection scope of the present invention.

[0067] Example 1:

[0068] This example provides a quantitative analysis method for the contents of LLM-105 and PYX in a mixed explosive, including:

[0069] 1. Preparation of the tetrachloroethane / carbon tetrachloride internal standard solution: Weigh about a certain amount of carbon tetrachloride, 7.2791 g (analytical pure), into a clean and dry volumetric flask, and then add 54.2409 g of tetrachloroethane (analytical pure). Cover the flask with a cap and shake well to mix evenly. Use it as the internal standard solution, and the mass fraction of tetrachloroethane in the standard solution is 11.83%.

[0070] 2. Sample preparation: Weigh approximately 8.0 mg (accurate to 0.1 mg) of the sample into a nuclear magnetic resonance tube, add a tube of deuterated dimethyl sulfoxide solvent (about 0.6 mL), put on the cap, and use ultrasonic assistance to fully dissolve the sample; add approximately 15.0 mg (accurate to 0.1 mg) of the prepared tetrachloroethane / carbon tetrachloride internal standard solution to the dissolved sample, shake well, and use it for nuclear magnetic resonance testing; prepare six groups of samples in parallel.

[0071] 3. Sample analysis: Set the test conditions of the high-resolution superconducting nuclear magnetic resonance spectrometer, select an 800M superconducting nuclear magnetic resonance spectrometer, use a single-pulse sequence, and collect the 1 1H nuclear magnetic resonance spectra of six groups of prepared samples. Set the relaxation delay time to 10 s and the number of scans to 128 times; put the nuclear magnetic resonance tube containing the prepared sample into the superconducting magnet for sample detection. The quantitative 1 1H nuclear magnetic resonance spectrum of a certain mixed explosive A is shown in Figure 2 , and the comparison diagrams of the 1 1H nuclear magnetic resonance spectra (left) and the enlarged region from 8 - 10 ppm (right) of LLM-105 and PYX pure components with a certain mixed explosive A.

[0072] 4. Peak fitting of characteristic groups of LLM-105 and PYX: Since there is partial overlap of the characteristic signals of -NH2 in LLM-105 and -C=CH- in PYX, use the dmfit software to perform peak fitting on the signals, and select the Gaussian / Lorentz mode. The fitting spectra are shown in Figure 3 , the peak area fitting diagrams of the characteristic groups of LLM-105 and PYX in a certain mixed explosive A. Among them, the black solid line is the experimental spectrum, the red solid line is the fitting spectrum, and the dotted line is the fitting curve of the corresponding characteristic peak. The peaks at 9.12 and 8.86 ppm are the 1 1H spectral signals of the characteristic group -C=CH- in PYX, and the peaks at 8.77 and 9.05 ppm are the 1 1H spectral signals of the characteristic group -NH2 in LLM-105.

[0073] 5. Calculation of the contents of LLM-105 and PYX components: Compare the peak area or peak height caused by the protons on the characteristic groups of LLM-105 and PYX components with the peak area caused by the protons on the -CH group in the internal standard substance tetrachloroethane to obtain the absolute contents of the two components of LLM-105 and PYX in the mixed explosive. The specific calculation formulas refer to Formula (1) and Formula (2), and the results are shown in Table 1.

[0074] Table 1 Test results of the contents of LLM-105 and PYX components in a certain mixed explosive A

[0075]

[0076] 6. Method verification: Accurately weigh 29.8 mg of PYX and 43.3 mg of LLM-105 and mix them evenly. Then weigh approximately 8.0 mg (accurate to 0.1 mg) of the sample into an NMR tube and conduct the experiment according to the steps in 1-5 above. The results are shown in Table 2.

[0077] Table 2 Verification experiment results

[0078]

Claims

1. A quantitative analysis method for the contents of LLM-105 and PYX in a composite explosive, characterized in that, This method uses high-resolution superconducting nuclear magnetic 1 H nuclear magnetic resonance spectroscopy for quantitative nuclear magnetic resonance to obtain the chemical shifts of characteristic groups of the sample LLM-105 and PYX components. Peak fitting is performed through the peak-fitting model Gaussian / Lorentz model. At the same time, tetrachloroethane / carbon tetrachloride is used as the internal standard substance. By comparing the peak areas caused by the protons on the characteristic groups of the LLM-105 and PYX components with the peak areas caused by the protons on the -CH group in the internal standard substance, the absolute contents of the two components of LLM-105 and PYX in the mixed explosive are obtained, realizing the accurate analysis of the contents of the LLM-105 and PYX components in the mixed explosive.

2. The quantitative analysis method for the contents of LLM-105 and PYX in the composite explosive according to claim 1, characterized in that, Including the following steps: s1, Preparation of the internal standard substance tetrachloroethane / carbon tetrachloride internal standard solution: Weigh m b g of carbon tetrachloride into a dry volumetric flask, and then add m a g of tetrachloroethane, shake well, and use it as the internal standard solution; S2, sample preparation: Weigh m1 mg of the sample into a nuclear magnetic resonance tube, add deuterated dimethyl sulfoxide solvent, and use ultrasonic assistance to fully dissolve the sample; add approximately m0 mg of the prepared tetrachloroethane / carbon tetrachloride internal standard solution to the dissolved sample, and shake well for nuclear magnetic resonance testing; S3, Sample analysis: Set the test conditions of the high-resolution superconducting nuclear magnetic resonance spectrometer, select the single-pulse sequence, and collect the sample 1 1H nuclear magnetic spectrum, set the relaxation delay time to ≥10 s, and set the number of scans to ≥128 times; Put the nuclear magnetic tube containing the prepared sample into the superconducting nuclear magnetic resonance, and perform sample detection; S4, calculation of the component contents of LLM-105 and PYX: Since there is partial overlap in the characteristic signals of the characteristic groups -NH2 of LLM-105 and -C=CH- of PYX, use a peak separation software to perform peak separation fitting on the signals, and select the Gaussian / Lorentz mode; finally, calculate the percentage contents of LLM-105 and PYX by comparing the peak areas caused by the protons on the characteristic groups of LLM-105 and PYX with the peak area caused by the protons on the -CH group in the internal standard substance tetrachloroethane.

3. The quantitative analysis method for the contents of LLM-105 and PYX in the composite explosive according to claim 2, characterized in that, The percentage contents of the said LLM-105 and PYX are calculated according to formulas (1) and (2): In the formulas: W1 - the percentage content of LLM-105, %; W2 - the percentage content of PYX, %; h1——LLM-105 nuclear magnetic 1 Peak area of the H spectrum; h2——PYX nuclear magnetic 1 Peak area of the H spectrum; h s —— 1,1,2,2 - Tetrachloroethane NMR 1 Peak area of the H spectrum; n1 - the number of H atoms in the -NH2 structure of LLM-105, 4; n2 - the number of H atoms in the -C=CH- structure of PYX, 5; n s —— The number of H atoms in the -CH structure in tetrachloroethane is 2; M1 - the relative molecular mass of LLM-105, 216 g / mol; M2 - the relative molecular mass of PYX, 621 g / mol; M s —— The relative molecular mass of tetrachloroethane, 168 g / mol; m a —— Mass of tetrachloroethane weighed, g; m b —— Mass of carbon tetrachloride weighed, g; m0 - the mass of the weighed internal standard solution, mg; m1 - the mass of the weighed sample, mg; Each sample is determined in parallel for six groups, the relative standard deviation of the parallel results is not more than 2%, and the result is taken as its arithmetic mean, expressed to two decimal places.

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