阅读说明：本技术 一种利用气相色谱检测复合固体推进剂中乙腈含量的方法 (Method for detecting acetonitrile content in composite solid propellant by using gas chromatography ) 是由 张翠珍 王吉强 张宇 李�杰 郑晓林 于科青 陈志鸿 于 2020-12-22 设计创作，主要内容包括：本发明提供一种利用气相色谱检测复合固体推进剂中乙腈含量的方法,包括如下步骤：内标溶液的配制、待测样品溶液配制、气相色谱检测条件选择、校正曲线的绘制和待测样品的检测。本发明可以准确的检测出复合固体推进剂中残留乙腈的含量,本发明测量效果好且测量精准,方法简便快捷,重复性好,适合微量组分的测定。(The invention provides a method for detecting acetonitrile content in a composite solid propellant by using gas chromatography, which comprises the following steps: preparing an internal standard solution, preparing a sample solution to be detected, selecting gas chromatography detection conditions, drawing a correction curve and detecting a sample to be detected. The method can accurately detect the content of the residual acetonitrile in the composite solid propellant, has good measurement effect and accurate measurement, is simple, convenient and quick, has good repeatability, and is suitable for measuring trace components.)

1. A method for detecting the acetonitrile content in a composite solid propellant by using gas chromatography is characterized by comprising the following steps:

s1: preparation of internal standard solution

Weighing analytically pure acetonitrile into a volumetric flask of 100mL respectively, adding tetrahydrofuran for diluting to constant volume, shaking up, and preparing tetrahydrofuran solutions with mass concentrations of 0.8mg/mL, 1.6mg/mL, 2.4mg/mL, 4.0mg/mL and 8.0mg/mL acetonitrile as internal standard sample solutions;

s2: preparation of sample solution to be tested

Weighing about 2g of propellant slurry sample, placing the sample in a 6mL reagent bottle, adding 2.0mL of tetrahydrofuran of analytical grade by using a transfer pipette, quickly stirring uniformly, covering a bottle stopper tightly, dissolving for about 12h, and taking supernatant as a sample solution to be detected;

s3: gas chromatography detection condition selection

A chromatographic column: a 5% phenyl-methyl polysiloxane gas phase capillary column of 15 mx 0.53mm x 5 μm;

sample introduction amount: 0.2 μ L, injection port temperature: 160 ℃, split ratio: 30: 1;

carrier gas: n is a radical of₂Flow rate: 1.5 mL/min;

a detector: hydrogen flame ionization detector FID, detector temperature: 260 ℃;

temperature rising procedure: the initial temperature is 60 ℃, and the temperature is maintained for 2min; heating to 120 deg.C at a rate of 10 deg.C, heating to 160 deg.C at a rate of 10 deg.C/min, and maintaining for 2min;

and (3) sample introduction mode: split-flow sample injection is adopted, and the split-flow ratio is 30: 1;

measuring the peak area by adopting electron integration;

s4: drawing of calibration curves

Injecting 0.2 mu L of internal standard solution into the gas chromatogram, measuring the peak areas of acetonitrile and tetrahydrofuran according to the gas chromatogram conditions, repeating for three times, drawing a correction curve by taking the concentration value of the acetonitrile as a horizontal coordinate and the peak area ratio of the acetonitrile to the tetrahydrofuran as a vertical coordinate, wherein the standard regression equation is as follows:

y =1550.1097X-0.4261, and the correlation coefficient r is 0.9983;

s5: detection of a sample to be tested

And (3) carrying out multiple average sample introduction on the sample to be detected in the S2 according to gas chromatography conditions, wherein the sample introduction amount is 0.2 mu L, obtaining the peak area ratio of the sample and the internal standard substance through a chromatogram, and calculating the acetonitrile content in the composite solid propellant according to the mass ratio of the internal standard calibration curve in the S4.

Technical Field

The invention relates to the field of detection of composite solid propellants of solid rocket engines, in particular to a method for detecting the acetonitrile content in a composite solid propellant by using gas chromatography.

Background

In the propellants used in certain engines, a "wet-on" process of bonding agent is used. The bonding agent is firstly dispersed in acetonitrile, then mixed with other components, and the solvent acetonitrile is removed by vacuumizing in the casting process. The acetonitrile has largely evaporated, but the propellant is still a slurry mixture in which traces of acetonitrile may remain. Residual acetonitrile can adversely affect combustion, energy and mechanical properties and can subsequently potentially compromise storage aging. At present, a method for measuring the residual acetonitrile in the propellant slurry is not reported, so that an effective measuring method for monitoring the content of the residual acetonitrile in the propellant slurry has certain practical significance.

Disclosure of Invention

The invention provides a method for detecting the content of acetonitrile in a composite solid propellant by using gas chromatography, which is used for detecting the content of acetonitrile remained in the composite solid propellant.

In order to solve the technical problem, the invention provides a method for detecting the acetonitrile content in a composite solid propellant by using gas chromatography, which comprises the following steps:

s1: preparation of internal standard solution

Weighing analytically pure acetonitrile into a volumetric flask of 100mL respectively, adding tetrahydrofuran for diluting to constant volume, shaking up, and preparing tetrahydrofuran solutions with mass concentrations of 0.8mg/mL, 1.6mg/mL, 2.4mg/mL, 4.0mg/mL and 8.0mg/mL acetonitrile as internal standard sample solutions;

s2: preparation of sample solution to be tested

Weighing about 2g of propellant slurry sample, placing the sample in a 6mL reagent bottle, adding 2.0mL of tetrahydrofuran of analytical grade by using a transfer pipette, quickly stirring uniformly, covering a bottle stopper tightly, dissolving for about 12h, and taking supernatant as a sample solution to be detected;

s3: gas chromatography detection condition selection

The gas-phase capillary column adopts 5% phenyl-methyl polysiloxane with the thickness of 15m multiplied by 0.53mm multiplied by 5 mu m, carrier gas is high-purity nitrogen, the flow rate of the carrier gas is 1.5mL/min, the chromatographic column is subjected to temperature programming, the initial column temperature is 60 ℃, the temperature is kept for 2min, the temperature is increased to 120 ℃ at the speed of 10 ℃/min, the temperature is kept for 2min, the temperature of a sample injector is 160 ℃, the temperature of a detector is 260 ℃, split sampling is adopted, and the split ratio is 30: 1, measuring the peak area by adopting electron integration;

s4: drawing of calibration curves

Injecting 0.2 mu L of internal standard solution into the gas chromatogram, measuring the peak areas of acetonitrile and tetrahydrofuran according to the gas chromatogram conditions, repeating for three times, drawing a correction curve by taking the concentration value of the acetonitrile as a horizontal coordinate and the peak area ratio of the acetonitrile to the tetrahydrofuran as a vertical coordinate, wherein the standard regression equation is as follows:

y =1550.1097X-0.4261, and the correlation coefficient r is 0.9983;

s5: detection of a sample to be tested

And (3) carrying out multiple average sample introduction on the sample to be detected in the S2 according to gas chromatography conditions, wherein the sample introduction amount is 0.2 mu L, obtaining the peak area ratio of the sample and the internal standard substance through a chromatogram, and calculating the acetonitrile content in the composite solid propellant according to the mass ratio of the internal standard calibration curve in the S4.

According to the method for detecting the acetonitrile content in the composite solid propellant by using the gas chromatography, the (5% phenyl) -methyl polysiloxane gas capillary column is adopted as the chromatographic column, so that the peak appearance effect of detecting the trace acetonitrile content in the composite solid propellant sample by using the gas chromatography is good, tetrahydrofuran is selected as an internal standard substance, a peak area internal standard method is adopted, the measurement effect is good, the measurement is accurate, the method is simple, convenient and quick, the repeatability is good, the method is suitable for measuring trace components, the sensitivity is high, the method is suitable for measuring compounds with low concentration in a solution, the method is simple and practical, the accuracy is good, and therefore, the method for identifying and quantitatively measuring the trace acetonitrile content in the composite solid propellant sample by using the gas chromatography is an ideal technical means at present.

Drawings

FIG. 1 is a chromatogram of a standard sample in example 1 of the present invention;

FIG. 2 is a chromatogram of a sample from example 1 of the present invention.

Detailed Description

The technical solution of the present invention is described below clearly and completely with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the obtained embodiments. All other embodiments that can be derived from the embodiments of the present invention by a person of ordinary skill in the art are within the scope of the present invention.

Example 1

A method for detecting the acetonitrile content in a composite solid propellant by using gas chromatography comprises the following steps:

s1: preparation of internal standard solution

Weighing analytically pure acetonitrile into a volumetric flask of 100mL respectively, adding tetrahydrofuran for diluting to constant volume, shaking up, and preparing tetrahydrofuran solutions with mass concentrations of 0.8mg/mL, 1.6mg/mL, 2.4mg/mL, 4.0mg/mL and 8.0mg/mL acetonitrile as internal standard sample solutions;

s2: preparation of sample solution to be tested

Weighing about 2g of propellant slurry sample, placing the sample in a 6mL reagent bottle, adding 2.0mL of tetrahydrofuran of analytical grade by using a transfer pipette, quickly stirring uniformly, covering a bottle stopper tightly, dissolving for about 12h, and taking supernatant as a sample solution to be detected;

s3: gas chromatography detection condition selection

Chromatograph: a gas chromatograph model SHIMADZU GC-2010-Pro;

a chromatographic column: a 5% phenyl-methyl polysiloxane gas phase capillary column of 15 mx 0.53mm x 5 μm;

sample introduction amount: 0.2 μ L, injection port temperature: 160 ℃, split ratio: 30: 1;

carrier gas: n is a radical of₂Flow rate: 1.5 mL/min;

a detector: hydrogen flame ionization detector FID, detector temperature: 260 ℃;

temperature rising procedure: the initial temperature is 60 ℃, and the temperature is maintained for 2min; heating to 120 deg.C at a rate of 10 deg.C, heating to 160 deg.C at a rate of 10 deg.C/min, and maintaining for 2min;

and (3) sample introduction mode: split-flow sample injection is adopted, and the split-flow ratio is 30: 1;

measuring the peak area by adopting electron integration;

s4: drawing of calibration curves

Injecting 0.2 mu L of internal standard solution into the gas chromatogram, measuring the peak areas of acetonitrile and tetrahydrofuran according to the gas chromatogram conditions, repeating for three times, drawing a correction curve by taking the concentration value of the acetonitrile as a horizontal coordinate and the peak area ratio of the acetonitrile to the tetrahydrofuran as a vertical coordinate, wherein the standard regression equation is as follows:

y =1550.1097X-0.4261, and the correlation coefficient r is 0.9983;

the acetonitrile standard sample solution has a good linear relation in a linear range of 0.8 mg/mL-8.0 mg/mL;

s5: detection of a sample to be tested

And (3) carrying out multiple average sample introduction on the sample to be detected in the S2 according to gas chromatography conditions, wherein the sample introduction amount is 0.2 mu L, obtaining the peak area ratio of the sample and the internal standard substance through a chromatogram, and calculating the acetonitrile content in the composite solid propellant according to the mass ratio of the internal standard calibration curve in the S4.

The test results of the content of the trace acetonitrile in the composite solid propellant slurry prepared by different processes are shown in table 1.

TABLE 1 test results of the samples

Treatment process	Acetonitrile/%)
		Process 1	0.33
Process 2	0.24
		Process 3	0.11
Process 4	0.04
		Process 5	Not detected out

Table 1 shows that the method can effectively guide the treatment process of the composite solid propellant slurry.

In order to further verify the detection accuracy, the detection accuracy is verified by adopting a standard addition recovery method in the embodiment, standard solutions with three concentration levels (1mg/mL, 3mg/mL and 5mg/mL) are respectively added into the same composite solid propellant sample to be detected, 3 parallel samples are set for each standard addition concentration sample, and the average standard addition recovery rate under the three concentration levels is calculated. The result shows that the recovery rate of each target object is 93.1-105.4% at the standard addition level (1-5 mg/mL), which indicates that the recovery rate of the method is high. The instrument detection limit (the lowest detection concentration corresponding to 3 times of signal to noise ratio) of the target substance is 0.7 mug/mL, which indicates that the method has higher sensitivity and meets the requirements of actual analysis and detection.

To further verify the reproducibility of the assay results, the reproducibility of the assay results are shown in table 2.

TABLE 2 repeatability of test results

Measurement results	Sample # 1%	Sample 2 #/%)
			1	0.33	0.23
2	0.36	0.24
			3	0.37	0.23
4	0.34	0.25
			5	0.36	0.22
Mean value/%)	0.35	0.23
			RSD/%	4.7	4.9

And (4) conclusion: as can be seen from figure 1, the acetonitrile peak and the tetrahydrofuran peak in the standard solution have no interference before and after, and the peak type is good; as can be seen from FIG. 2, acetonitrile is detected to be remained in the chromatogram of the sample of the composite solid propellant slurry. As can be seen from Table 2, the relative standard deviation RSD of the method is less than 5%, which shows that the method has better repeatability and can meet the actual measurement requirement.