CN111665312A - Method for detecting content of N-methylimidazole in water phase system - Google Patents
Method for detecting content of N-methylimidazole in water phase system Download PDFInfo
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- CN111665312A CN111665312A CN202010622287.7A CN202010622287A CN111665312A CN 111665312 A CN111665312 A CN 111665312A CN 202010622287 A CN202010622287 A CN 202010622287A CN 111665312 A CN111665312 A CN 111665312A
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
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Abstract
The invention discloses a method for detecting the content of N-methylimidazole in an aqueous phase system, which belongs to the technical field of N-methylimidazole content determination.
Description
Technical Field
The invention relates to the technical field of N-methylimidazole content determination, in particular to a method for detecting N-methylimidazole content in an aqueous phase system.
Background
N-methylimidazole is an important fine chemical raw material and intermediate, and has wide application. N-methylimidazole is mainly used as an organic synthesis intermediate, such as an ionic liquid, a resin curing agent and an adhesive, and is also an active ingredient of many pesticides, enzyme inhibitors, medicaments and fine chemicals. During the synthesis of N-methylimidazole, the realization of the rapid and accurate detection of the product content in the aqueous phase synthesis stock solution has important significance for controlling the yield.
For the detection of products in organic reactions, the traditional method for detecting products after separation and purification is time-consuming and labor-consuming, and is not suitable for controlling the reaction process in industrial production. The synthetic stock solution can be directly detected by an ultraviolet spectrophotometer or an Abbe refractometer, and the product content in the stock solution is calculated according to a standard curve obtained in advance. However, the components of the actual synthetic stock solution are complex, and the system contains byproducts of the reaction and unreacted raw materials, which interfere the detection of an ultraviolet spectrophotometer or an abbe refractometer, so that the detection result has large errors, and the content of the N-methylimidazole is difficult to accurately obtain. By selecting a proper chromatographic system, the gas chromatography can accurately measure the content of various volatile organic components, and is a common method for detecting the content of products in organic media. However, in the case of a synthesis system of N-methylimidazole containing a large amount of water, the measurement of the aqueous phase synthesis stock solution by gas chromatography is seriously disturbed by the water content, so that the gas chromatography is not suitable for determining the content of N-methylimidazole in the aqueous solution.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for detecting the content of N-methylimidazole in an aqueous phase system, which is characterized in that ethylene glycol is used as an internal standard substance, N, N-dimethylformamide is used as a diluting solvent, a correction factor is obtained through a working curve of ethylene glycol and N-methylimidazole, quantitative analysis is carried out to detect the content of N-methylimidazole in the aqueous phase system, and the method is high in accuracy, good in stability, wide in linear range, simple, convenient and rapid.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for detecting the content of N-methylimidazole in an aqueous phase system comprises the following steps:
s1, quantitative method: adopting an internal standard method, wherein the internal standard substance adopts ethylene glycol, and the sample is dissolved by adopting N, N-dimethylformamide;
s2, drawing a working curve: respectively preparing mixed solutions of glycol and pure N-methylimidazole with different proportions, diluting with N, N-dimethylformamide to a constant volume of 50ml, wherein the sample injection amount is 0.4 mu l, measuring peak areas of the glycol and the pure N-methylimidazole by using a gas chromatograph to obtain peak area ratios under different mass ratios, and drawing a working curve to obtain a correction factor;
s3, detection of the sample to be detected: accurately weighing 1.8000-2.2000g of sample to be detected in a 50ml volumetric flask, adding 0.5500-0.6500g of ethylene glycol, performing constant volume by using N, N-dimethylformamide, wherein the sample injection amount is 0.4 mu l, calculating the peak area ratio of an internal standard substance and the sample from a spectrogram obtained by a gas chromatograph, calculating the content of the internal standard substance and the sample according to the correction factor obtained in the step S2, performing average sample injection for three times, and taking an average value.
Preferably, in step S2, the ratio of ethylene glycol to pure N-methylimidazole is 3:1, 2:1, 1:2, 1:3, and a new ratio may be added within the range of the ratio of 3:1, 2:1, 1:2, 1: 3.
Preferably, in the step S2, a standard working curve is drawn by using a peak area ratio of ethylene glycol and N-methylimidazole as a ordinate and a mass ratio as an abscissa, so as to obtain a correction factor.
Preferably, the ethylene glycol is chromatographically pure.
Preferably, the N, N-dimethylformamide is analytically pure.
The beneficial technical effects of the invention are as follows: the invention adopts ethylene glycol as an internal standard substance and N, N-dimethylformamide as a diluting solvent, and both the ethylene glycol and the N-methylimidazole can be well mixed with the synthetic stock solution; n, N-dimethylformamide is used as a diluting solvent, the synthetic stock solution is diluted, the influence of the presence of water in the stock solution on a detection result is reduced, and the problem that the measurement of the gas chromatography on the aqueous phase synthetic stock solution is seriously interfered by the presence of a large amount of water is solved; in gas chromatography detection, the outflow time of ethylene glycol and N, N-dimethylformamide is obviously different from that of N-methylimidazole and other organic components in a synthetic stock solution, signal peaks on a gas chromatogram map are not overlapped and are not interfered by other organic components in the synthetic stock solution, and an obtained working curve has a good linear relationship in a wide range, so that the working curve of ethylene glycol and N-methylimidazole can be obtained by using ethylene glycol as an internal standard substance and N, N-dimethylformamide as a diluting solvent, and the content of N-methylimidazole in an aqueous phase system is quantitatively analyzed and detected; the price of the internal standard substance and the diluting solvent is low and non-toxic, the sample treatment is simple, the precision is high, the stability is good, the linear range is wide, and the analysis is free of interference, simple, convenient and quick.
Drawings
FIG. 1 is a gas chromatogram of a standard solution according to the invention;
fig. 2 is a graph of the operation of the present invention.
Detailed Description
The present invention will be further described with reference to the following specific examples.
Example 1
A method for detecting the content of N-methylimidazole in an aqueous phase system comprises the following steps:
s1, quantitative method: adopting an internal standard method, adopting chromatographic grade ethylene glycol as an internal standard substance, and adopting analytically pure N, N-dimethylformamide for dissolving a sample;
s2, drawing a working curve: pure N-methylimidazole was used as standard, according to ethylene glycol: the ratio of N-methylimidazole is 3:1, 2.5:1, 2:1, 1.5: 1. weighing an N-methylimidazole standard sample and an ethylene glycol standard sample at a ratio of 1:1, 1:2 and 1:3, diluting with N, N-dimethylformamide to a constant volume of 50ml, wherein the sample injection amount is 0.4 mu l, measuring peak areas of ethylene glycol and pure N-methylimidazole by using a gas chromatograph to obtain peak area ratios of the ethylene glycol and the pure N-methylimidazole under different mass ratios, and drawing a working curve to obtain a correction factor;
the gas chromatogram of the standard solution is shown in FIG. 1, wherein the peak at the position of outflow time of 2.2min is an ethylene glycol signal peak, the position of 2.4min is an N, N-dimethylformamide signal peak, and the peak does not overlap with the N-methylimidazole signal peak and other signal peaks at the outflow time of 3.3min, and has good peak pattern; the obtained working curve is shown in fig. 2, wherein the mass and mass ratio of ethylene glycol and N-methylimidazole corresponding to the working curve to the area ratio are shown in table 1, and the working curve has good linearity.
TABLE 1
S3, detection of the sample to be detected: 2.1137g of sample # 1 to be tested is accurately weighed in a 50ml volumetric flask, 0.5718g of ethylene glycol is added, the volume is determined by N, N-dimethylformamide, the sample introduction amount is 0.4 mu l, the peak area ratio of the internal standard substance to the sample is calculated from a spectrogram obtained by a gas chromatograph, the content of the internal standard substance to the sample is calculated according to the correction factor obtained in the step S2, the detection is repeated for 3 times, the average value is taken, and the test results are shown in Table 2.
Example 2
2.0983g of sample # 2 to be tested is accurately weighed in a 50ml volumetric flask, 0.5704g of ethylene glycol is added, the volume is determined by N, N-dimethylformamide, the sample is injected according to the gas chromatography condition, the injection amount is 0.4 mu l, the peak area ratio of the internal standard substance and the sample is calculated from the spectrogram obtained by a gas chromatograph, the content of the internal standard substance and the sample is calculated according to the correction factor obtained in the step S2 in the embodiment 1, the average value is obtained by repeating the detection for 3 times, and the test result is shown in Table 2.
Example 3
2.0762g of sample # 3 to be tested is accurately weighed in a 50ml volumetric flask, 0.5889g of ethylene glycol is added, the volume is determined by N, N-dimethylformamide, the sample is injected according to the gas chromatography condition, the injection amount is 0.4 mu l, the peak area ratio of the internal standard substance and the sample is calculated from the spectrogram obtained by a gas chromatograph, the content of the internal standard substance and the sample is calculated according to the correction factor obtained in the step S2 in the embodiment 1, the average value is obtained by repeating the detection for 3 times, and the test result is shown in Table 2.
TABLE 2 actual sample test results
Methodology investigation:
the test was repeated 5 times using a standard solution of the same concentration of N-methylimidazole, and the results are shown in Table 3 below.
TABLE 3 repeatability test results
As can be seen from Table 3, the relative standard deviation of the peak area ratio of the repeated tests is 0.03%, which shows that the precision of the correction factor detected by the method is high and the reproducibility is good.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and variations which do not require inventive efforts and are made by those skilled in the art are still within the scope of the present invention.
Claims (5)
1. A method for detecting the content of N-methylimidazole in an aqueous phase system is characterized by comprising the following steps:
s1, quantitative method: adopting an internal standard method, wherein the internal standard substance adopts ethylene glycol, and the sample is dissolved by adopting N, N-dimethylformamide;
s2, drawing a working curve: respectively preparing mixed solutions of glycol and pure N-methylimidazole with different proportions, diluting with N, N-dimethylformamide to a constant volume of 50ml, wherein the sample injection amount is 0.4 mu l, measuring peak areas of the glycol and the pure N-methylimidazole by using a gas chromatograph to obtain peak area ratios under different mass ratios, and drawing a working curve to obtain a correction factor;
s3, detection of the sample to be detected: accurately weighing 1.8000-2.2000g of sample to be detected in a 50ml volumetric flask, adding 0.5500-0.6500g of ethylene glycol, performing constant volume by using N, N-dimethylformamide, wherein the sample injection amount is 0.4 mu l, calculating the peak area ratio of an internal standard substance and the sample from a spectrogram obtained by a gas chromatograph, calculating the content of the internal standard substance and the sample according to the correction factor obtained in the step S2, performing average sample injection for three times, and taking an average value.
2. The method for detecting the content of N-methylimidazole in the aqueous phase system as claimed in claim 1, wherein in step S2, the ratio of ethylene glycol to pure N-methylimidazole is 3:1, 2:1, 1:2, 1:3, and a new ratio can be added within the range of the ratio of 3:1, 2:1, 1:2, 1: 3.
3. The method according to claim 1, wherein in step S2, a standard working curve is drawn by using a peak area ratio of ethylene glycol to N-methylimidazole as an ordinate and a mass ratio as an abscissa, so as to obtain the calibration factor.
4. The method for detecting the content of N-methylimidazole in an aqueous system as claimed in claim 1, wherein the ethylene glycol is chromatographically pure.
5. The method for detecting the content of N-methylimidazole in an aqueous system as claimed in claim 1, wherein the N, N-dimethylformamide is analytically pure.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114200037A (en) * | 2021-11-11 | 2022-03-18 | 山东中科恒联生物基材料有限公司 | Method for detecting purity of ionic liquid in preparation of regenerated cellulose material |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114200037A (en) * | 2021-11-11 | 2022-03-18 | 山东中科恒联生物基材料有限公司 | Method for detecting purity of ionic liquid in preparation of regenerated cellulose material |
| CN114200037B (en) * | 2021-11-11 | 2024-04-05 | 山东中科恒联生物基材料有限公司 | Method for detecting purity of ionic liquid in preparation of regenerated cellulose material |
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Application publication date: 20200915 |