Quantitative analysis method for purity of pentazole ionic salt

Abstract

The invention provides a quantitative analysis method for purity of pentazole ionic salt, which comprises the following steps: step 1, weighing a pentazole cobalt standard substance, dissolving and preparing pentazole cobalt standard solutions with different concentrations; 2, weighing a to-be-detected pentazole ionic salt crude product, and dissolving to obtain a to-be-detected pentazole ionic salt crude product solution; step 3, setting ion chromatography conditions, and testing the prepared pentazole cobalt standard solutions with different concentrations to obtain peak areas of pentazole anions under different concentrations; step 4, testing the to-be-tested pentazole ion salt crude product solution in the step 2 and the same sample size in the step 3 under the same condition to obtain a corresponding peak area; and 5, making a standard curve according to the peak areas of the pentazole anions at different concentrations obtained in the step 3 and the concentrations, obtaining the molar concentration of the pentazole anions in the crude product solution of the to-be-detected pentazole ionic salt by an external standard method, and calculating to obtain the purity of the crude product of the to-be-detected pentazole ionic salt. The method disclosed by the invention is convenient to operate, high in accuracy and suitable for quantitatively analyzing the purity of various pentazole ion salt crude products.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of analytical chemistry, and relates to a pentazolate ion salt, in particular to a quantitative analysis method for the purity of a pentazolate ion salt. BACKGROUND

[0002] Traditional energetic materials (such as 2,4,6-trinitrotoluene and 1,3,5-trinitro-1,3,5-triazacyclohexane) have limited energy density, while all-nitrogen compounds (such as N5 — and N8) become a breakthrough direction due to the high energy storage characteristics of the nitrogen-nitrogen bond. The pentazolate anion (N5 — ) as a stable all-nitrogen cyclic structure releases much more energy than conventional materials when it is decomposed, and is regarded as a candidate for the next generation of high-energy explosives and propellants. Due to its special chemical structure and characteristics, it is difficult for conventional analysis methods to quantitatively analyze the content of the pentazolate anion, which seriously affects the quality control of the synthesis process of the pentazolate-based energetic material and hinders the in-depth study of the energetic material. Therefore, there is an urgent need for a quantitative analysis method for the content of the pentazolate anion which is simple to operate and has high accuracy. SUMMARY

[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide a quantitative analysis method for the purity of a pentazolate ion salt, which solves the technical problem that the quantitative analysis method for the purity of a pentazolate ion salt in the prior art cannot simultaneously improve efficiency and accuracy.

[0004] In order to solve the above technical problems, the present application adopts the following technical solutions: A quantitative analysis method for the purity of a pentazolate ion salt, which specifically comprises the following steps: Step 1: Preparation of a pentazolate cobalt standard solution: Weigh the pentazolate cobalt standard, dissolve it in water and dilute it to prepare pentazolate cobalt standard solutions of different concentrations.

[0005] Step 2: Preparation of a crude pentazolate ion salt solution to be tested: Weigh the crude pentazolate ion salt to be tested, dissolve it in water and dilute it to obtain a crude pentazolate ion salt solution to be tested.

[0006] Step 3: Determination of the pentazolate cobalt standard solution: Set the ion chromatography conditions, filter the pentazolate cobalt standard solutions of different concentrations prepared in step 1 with a water phase filter membrane, and then test them to obtain the peak area of the pentazolate anion at different concentrations.

[0007] Step 4: Determination of the crude pentazolate ion salt solution to be tested: The ion chromatography conditions are set as the same as step three, the solution of the crude product of the to-be-tested pentaazole ionic salt in step two is filtered by a water phase membrane filter, and the peak area of the pentaazole anion in the crude product of the to-be-tested pentaazole ionic salt is obtained by testing in the same injection amount as that in step three.

[0008] Step five, purity calculation of the crude product of the to-be-tested pentaazole ionic salt: The peak area of the pentaazole anion at different concentrations obtained in step three is used as a standard curve, and the molar concentration of the pentaazole anion in the solution of the crude product of the to-be-tested pentaazole ionic salt is obtained by an external standard method, and the purity of the crude product of the to-be-tested pentaazole ionic salt is calculated.

[0009] The present application also has the following technical features: Specifically, in step one, the concentration of the pentaazole anion in the different concentrations of pentaazole cobalt standard solution is 0.513-7.974 mmol / L.

[0010] Specifically, in step two, the crude product of the to-be-tested pentaazole ionic salt includes a crude product of to-be-tested pentaazole sodium.

[0011] Specifically, in step three, the ion chromatography conditions are as follows: the ion chromatography instrument is a Metrohm 940Professional IC ion chromatography instrument; the chromatographic analysis column is a Metrosep A Supp anion chromatographic column with a specification of 4 mm*250 mm; the mobile phase is an acetonitrile aqueous solution containing 0.01-0.05 mol / L sodium carbonate; the flow rate is 0.2-1.5 mL / min; the column temperature is 20-60 DEG C; the detector is a conductivity detector; the injection amount is 2-50 mu L; and the analysis time is 11 min.

[0012] Compared with the prior art, the present application has the following technical effects: (I) The method in the present application uses pentaazole cobalt standard as an analysis standard, realizes quantitative analysis of the content of the pentaazole ionic salt in the crude product of the to-be-tested pentaazole ionic salt by ion chromatography and an external standard method, and compared with the prior art, the method is more convenient and accurate, and the method in the present application is not only suitable for quantitative analysis of the purity of the crude product of pentaazole sodium in the synthesis process, but also suitable for quantitative analysis of the purity of other types of crude products of pentaazole ionic salt, and has strong universality.

[0013] (II) The method in the present application uses pentaazole cobalt which has low solubility in water, and the pentaazole cobalt standard can be easily obtained with a required purity; compared with pentaazole sodium salt, the pentaazole cobalt standard can be obtained by multiple recrystallization of the crude product of pentaazole cobalt, and is suitable for quantitative analysis of the pentaazole anion.

[0014] (III) The method in the application carries out ion chromatography analysis on standard solution of different concentrations of pentaazocobalt to obtain a standard curve of pentaazole anion concentration and response signal, and analyzes the crude product of pentaazocobalt to be detected under the same chromatographic conditions to obtain the purity of the crude product of pentaazocobalt to be detected; the method is high in accuracy, good in precision and simple and feasible, and provides effective guarantee for quality control in the synthesis process of pentaazol-based energetic materials. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Figure 4 is an ion chromatogram of the pentaazocobalt standard solution with a pentaazole anion concentration of 2.827 mmol / L in the application.

[0016] Figure 2 Figure 5 is a standard curve diagram of the relationship between the pentaazole anion concentration and the peak area.

[0017] Figure 3 Figure 6 is an ion chromatogram of sample 1 in the embodiment of the application.

[0018] Figure 4 Figure 7 is an ion chromatogram of sample 2 in the embodiment of the application.

[0019] Figure 5 Figure 8 is an ion chromatogram of sample 3 in the embodiment of the application.

[0020] Figure 6 Figure 9 is an ion chromatogram of sample 4 in the embodiment of the application.

[0021] The specific content of the application is further described in detail below in combination with the drawings and examples. DETAILED DESCRIPTION

[0022] It should be noted that all the methods and raw materials in the application, if not specially stated, all use the commonly used methods and raw materials known in the art in the prior art, for example, the external standard method uses the known external standard method, the standard addition recovery method uses the known standard addition recovery method, the precision RSD calculation method uses the known precision RSD calculation method, the pentaazocobalt crude product uses the known pentaazocobalt crude product, the pentaazol ion salt crude product uses the known pentaazol ion salt crude product, and the deionized water uses the known commonly used deionized water.

[0023] In the application, the structural formula of the pentaazocobalt standard is The purity of the pentaazocobalt standard is > 99%; the pentaazocobalt standard is obtained by multiple recrystallization of pentaazocobalt crude product with methanol and deionized water.

[0024] In accordance with the above technical solution, the specific embodiments of the application are given below, and it should be noted that the application is not limited to the following specific embodiments, and any equivalent transformation based on the technical solution of the application falls within the protection scope of the application.

[0025] Embodiment: The embodiment provides a quantitative analysis method of the purity of a pentazole ion salt, and the method specifically comprises the following steps. Step 1: Preparation of a pentazole cobalt standard solution 0.0088 g, 0.0190 g, 0.0345 g, 0.0696 g and 0.1368 g of pentazole cobalt standard substance are accurately weighed, respectively dissolved in deionized water and diluted to 100 mL, and different concentrations of pentazole cobalt standard solutions are prepared.

[0026] In step 1, the pentazole anion concentration in the pentazole cobalt standard solutions with different concentrations is 0.513-7.974 mmol / L.

[0027] Step 2: Preparation of a to-be-tested pentazole sodium crude product solution Four to-be-tested pentazole sodium crude products synthesized at different times are accurately weighed, and the mass is 0.0456 g, 0.0752 g, 0.0865 g and 0.0936 g respectively, and is sequentially marked as sample 1 to sample 4, respectively dissolved in deionized water and diluted to 100 mL, and a to-be-tested pentazole sodium crude product solution is obtained.

[0028] In the embodiment, the to-be-tested pentazole ion salt crude product is a to-be-tested pentazole sodium crude product, the to-be-tested pentazole sodium crude product is a pentazole sodium salt crude product, the molecular formula of the pentazole sodium salt is NaH6N5O3, and the structural formula is ; the to-be-tested pentazole sodium crude product is a pentazole sodium crude product commonly known in the art, and the pentazole sodium salt is a pentazole sodium salt commonly known in the art.

[0029] In the embodiment, the four to-be-tested pentazole sodium crude products synthesized at different times are a pentazole sodium crude product without purification, a pentazole sodium crude product after deionized water purification, a pentazole sodium crude product after ethanol purification and a pentazole sodium crude product after methanol purification, and are sequentially named from sample 1 to sample 4; the products obtained after deionized water purification, ethanol purification and methanol purification of the pentazole sodium crude product are products obtained by a commonly known purification method in the art.

[0030] Step 3: Determination of the pentazole cobalt standard solution Ion chromatography conditions are set, the pentazole cobalt standard solutions with different concentrations prepared in step 1 are respectively filtered by a water phase filter membrane and then tested, and the peak area of the pentazole anion under different concentrations is obtained; the peak area of the pentazole anion in the pentazole cobalt standard solutions with different concentrations is shown in Table 1, and the ion chromatogram of the pentazole cobalt standard solution with a pentazole anion concentration of 2.827 mmol / L is shown in Figure 1 .

[0031] In step 3, the structural formula of the pentazole anion (N5 — ) is .

[0032] In step three, the ion chromatography conditions are as follows: the ion chromatograph is a Metrohm 940 Professional IC ion chromatograph; the chromatographic column is a Metrosep A Supp anion chromatographic column with a specification of 4 mm x 250 mm; the mobile phase is an acetonitrile aqueous solution containing 0.01 mol / L sodium carbonate; the flow rate is 0.7 mL / min; the column temperature is 50°C; the detector is a conductivity detector; the sample injection volume is 20 μL; and the analysis time is 11 min.

[0033] Table 1 Standard curve data table corresponding to the penta-azole cobalt standard

[0034] In this embodiment, the aqueous phase filter membrane filtration is commonly used in the art.

[0035] In this embodiment, the ion chromatograph with a model of Metrohm 940 Professional IC is commonly used in the art; the anion chromatographic column with a model of Metrosep A Supp and a specification of 4 mm x 250 mm is commonly used in the art; the sodium carbonate is commonly used in the art; and the acetonitrile aqueous solution (the volume ratio of acetonitrile to deionized water is 25:75) is commonly used in the art.

[0036] Step four, determination of the crude penta-azole sodium solution to be tested: The ion chromatography conditions are set to be the same as those in step three, the crude penta-azole sodium solution to be tested in step two is filtered with the aqueous phase filter membrane, and the sample injection volume is the same as that in step three to obtain the peak area of the penta-azole anion in the crude penta-azole sodium solution to be tested. The ion chromatogram results of sample 1 to sample 4 are shown in Figures 3 to 6 Table 2 is the test data of the purity of different crude penta-azole sodium to be tested.

[0037] Table 2 Test data of the purity of different crude penta-azole sodium to be tested

[0038] Step five, purity calculation of the crude penta-azole sodium to be tested: The peak area of the penta-azole anion at different concentrations obtained in step three is used to draw a standard curve with the concentration, and the molar concentration of the penta-azole anion in the crude penta-azole sodium solution to be tested is obtained by the external standard method. The purity of the crude penta-azole sodium to be tested is calculated.

[0039] In this embodiment, the purity of the crude pentazocine sodium to be tested is the content of pentazocine anions in the crude pentazocine sodium to be tested.

[0040] A working curve was fitted to show the relationship between the concentration of pentazolium anion and the peak area in the cobalt pentazolium standard solution, as follows: Figure 2 As shown, the linear equation is A = 4.9456C - 1.1187, and the correlation coefficient R0 is... 2 =0.9997, indicating that within the concentration range of 0.513 to 7.974 mmol / L, the molar concentration of pentazolium anion in the crude pentazolium sodium solution can be calculated by the response of the ion chromatography peak area.

[0041] Substituting the values ​​into the formula, the purity of the crude sodium pentaazole can be calculated. The specific calculation method is as follows: ; In the formula: w The purity of the crude sodium pentaazole to be tested; C The molar concentration of pentazolium anion in the crude pentazolium sodium solution to be tested is given in mmol / L. M The molar mass of sodium pentazolate is 147.07 g / mol. V The volume of the crude sodium pentaazole solution to be tested is in mL. m The mass of the crude sodium pentazolate to be tested is in grams.

[0042] This embodiment also performed six parallel determinations of the same crude pentazocine to be tested, and the RSD of the precision of the method in steps one to five in this embodiment was 0.45%. This embodiment also used the spiked recovery method to verify the accuracy of the method in steps one to five. Different concentrations of cobalt pentazocine standard solution were added to the crude pentazocine to be tested solution prepared with crude pentazocine to be tested of known purity, and the test was performed under the same ion chromatography conditions as in this embodiment, and the recovery rate was 97.1% to 102.8%.

Claims

1. A quantitative analysis method for the purity of pentazolium salts, characterized in that, The method specifically includes the following steps: Step 1, Preparation of cobalt pentazonite standard solution: Weigh the cobalt pentaazole standard, dissolve it in water and dilute to volume to prepare cobalt pentaazole standard solutions of different concentrations; Step 2, Preparation of the crude pentazolium salt solution to be tested: Weigh the crude pentaazole ion salt to be tested, dissolve it in water and make up to volume to obtain the crude pentaazole ion salt solution; Step 3, Determination of cobalt pentazolium standard solution: Set up ion chromatography conditions, filter the pentazolium cobalt standard solutions of different concentrations prepared in step one through an aqueous filter membrane and test them to obtain the peak area of ​​pentazolium anion at different concentrations. Step 4: Determination of the crude pentazolium salt solution to be tested: Set the same ion chromatography conditions as in step three, filter the crude pentazolium ion salt solution to be tested in step two using an aqueous filter membrane, and test it with the same injection volume as in step three to obtain the peak area of ​​the pentazolium anion in the crude pentazolium ion salt solution to be tested. Step 5: Calculation of the purity of the crude pentazolium ion salt to be tested: A standard curve was plotted using the area and concentration of the pentazolium anion peaks at different concentrations obtained in step three. The molar concentration of pentazolium anions in the crude pentazolium salt solution to be tested was obtained by external standard method, and the purity of the crude pentazolium salt to be tested was calculated.

2. The method for quantitative analysis of the purity of pentaazole ion salts as described in claim 1, characterized in that, In step one, the concentration of pentazolium anion in the cobalt pentazolium standard solutions of different concentrations ranges from 0.513 to 7.974 mmol / L.

3. The method for quantitative analysis of the purity of pentaazole ion salts as described in claim 1, characterized in that, In step two, the crude pentazolium ion salt to be tested includes crude sodium pentazolium to be tested.

4. The method for quantitative analysis of the purity of pentaazole ion salts as described in claim 1, characterized in that, In step three, the ion chromatography conditions are as follows: the ion chromatograph is a Metrohm 940 Professional IC; the analytical column is a Metrosep A Supp anion exchange column with a size of 4 mm × 250 mm; the mobile phase is an acetonitrile aqueous solution containing 0.01–0.05 mol / L sodium carbonate; the flow rate is 0.2–1.5 mL / min; the column temperature is 20–60 °C; the detector is a conductivity detector; the injection volume is 2–50 μL; and the analysis time is 11 min.

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