Detection method for measuring content of triethylamine in paraformaldehyde

Abstract

The invention discloses a detection method for measuring the content of triethylamine in paraformaldehyde, and belongs to the technical field of triethylamine detection. In order to solve the technical problem of low detection precision of triethylamine in paraformaldehyde in the prior art, the detection method for measuring the content of triethylamine in paraformaldehyde comprises the following steps: setting a high performance gas chromatograph according to chromatographic conditions; preparing a test sample by taking methanol as a solvent; and performing gas phase analysis on the test sample by using the high performance gas chromatograph with the chromatographic conditions set in the step S1. According to the method, after the paraformaldehyde is depolymerized, the gas chromatographic conditions are optimized, so that the detection precision of the triethylamine in the paraformaldehyde is effectively improved, and the detection limit of the content of the triethylamine in the paraformaldehyde is reduced to 1mg / g.

Description

Technical Field

[0001] The invention relates to the technical field of triethylamine detection, and in particular to a detection method for measuring the content of triethylamine in paraformaldehyde. Background Art

[0002] In the chemical industry and drug synthesis field, paraformaldehyde, as an important chemical raw material, is widely used in many industries such as resins, adhesives, dyes, and drugs. However, in the production process of paraformaldehyde, triethylamine is usually used as a catalyst, which leads to the residual triethylamine in the paraformaldehyde. Although triethylamine, as a common organic solvent and catalyst, is widely used in the fields of medicine, dyes, etc., its toxicity and flammable and explosive properties require that its content in the final product be strictly controlled.

[0003] The existing methods for measuring the content of triethylamine in paraformaldehyde mainly include acid-base titration, spectral analysis and chromatographic analysis. Gas chromatography has been widely used in the fields of drug residues and environmental pollutant analysis due to its advantages of high efficiency, high selectivity and high sensitivity. However, when traditional gas chromatography is used to process complex matrices such as paraformaldehyde, it is difficult to completely separate the triethylamine peak from other impurity peaks due to the matrix effect, which affects the accuracy of the test results. The detection accuracy of triethylamine in paraformaldehyde is low.

[0004] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0005] The object of the present invention is to provide a detection method for measuring the content of triethylamine in paraformaldehyde, so as to solve the technical problem of low detection accuracy of triethylamine in paraformaldehyde in the prior art.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A detection method for measuring the content of triethylamine in paraformaldehyde comprises the following steps:

[0008] S1. Set up a high performance gas chromatograph according to chromatographic conditions;

[0009] S2. Prepare the test sample using methanol as solvent;

[0010] S3, performing gas phase analysis on the test sample using a high performance gas chromatograph with the chromatographic conditions set in step S1;

[0011] S4. Calculate the content of triethylamine in the sample to be tested according to the calculation formula of the external standard method to obtain the content of triethylamine in the sample to be tested.

[0012] Further, in step S1, the chromatographic conditions are as follows:

[0013] Chromatographic model: GC2014C;

[0014] Chromatographic column: SK-5, 0.32mm×30m×0.25um;

[0015] Injection volume: 1.0uL;

[0016] Vaporization chamber temperature: 200℃;

[0017] Injection mode: split flow ratio: 50:1, linear velocity: 26.2 cm / sec;

[0018] Column temperature: 40°C, hold for 5 minutes, increase the temperature to 200°C at 20°C / min, hold for 2 minutes;

[0019] Testing room temperature: 250℃.

[0020] Furthermore, the sample preparation method is as follows: 5 g of the paraformaldehyde sample, 40 g of methanol and 0.5-1 g of an inorganic alkali solution are mixed, condensed and refluxed for 5 min in a water bath, the solution is clarified, and filtered for sampling.

[0021] Furthermore, the inorganic alkali solution is an aqueous solution of sodium hydroxide, potassium hydroxide or ammonium hydroxide, and the concentration of the inorganic alkali solution is 0.5-1.5 mol / L.

[0022] Furthermore, the external standard method calculation formula is: Wherein, W is the content, s is the peak area of ​​triethylamine detected by gas chromatography, f is the correction factor, and M is the weight of paraformaldehyde.

[0023] Further, the linear equation of triethylamine is y=117644x.

[0024] The present invention has the following beneficial effects:

[0025] The invention depolymerizes paraformaldehyde in a methanol solution through pretreatment, optimizes the configuration method of the paraformaldehyde sample and the gas chromatography conditions, can effectively promote the separation of triethylamine and paraformaldehyde, has the advantages of small interference, high sensitivity and the like. It has been verified that the invention has a low detection limit, high precision and accuracy, is easy to operate, and is easy to promote in laboratories. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is a detection spectrum of triethylamine content in paraformaldehyde in the test sample in Example 2 of the present invention;

[0028] Figure 2 It is the linear calibration curve of the sample in the linear test of the present invention. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] This embodiment provides a chromatographic condition for measuring the content of triethylamine in paraformaldehyde:

[0032] Chromatographic model: GC2014C;

[0033] Chromatographic column: SK-5, 0.32mm×30m×0.25um;

[0034] Injection volume: 1.0ul;

[0035] Vaporization chamber temperature: 200℃;

[0036] Injection mode: split flow ratio: 50:1, linear velocity: 26.2 cm / sec;

[0037] Column temperature: 40°C, hold for 5 minutes, increase the temperature to 200°C at 20°C / min, hold for 2 minutes;

[0038] Testing room temperature: 250℃.

[0039] Example 2

[0040] This embodiment provides a detection method for measuring the content of triethylamine in paraformaldehyde:

[0041] S1. Start-up preparation

[0042] According to the chromatographic conditions of Example 1, the high performance gas chromatograph was turned on and set;

[0043] S2. System balance

[0044] Detect the chromatographic slope, which is required to be less than 1000.

[0045] S3. Sample configuration

[0046] 5 g of paraformaldehyde sample, 40 g of methanol and 0.5 g of 1 mol / L sodium hydroxide solution were added to a flask and stirred. The flask was placed in a water bath and condensed and refluxed for 5 minutes. The system was dissolved and clarified, and filtered using a 0.22 um filter membrane to prepare a test sample.

[0047] S4, Linearity Test

[0048] Prepare linearity standard solution:

[0049] 10.51 mg, 23.82 mg, 34.86 mg, 45.31 mg and 51.48 mg of analytically pure triethylamine were accurately weighed, diluted to 10 g with methanol solution, and subjected to gas phase testing. The specific test results are shown in Table 1 below.

[0050] The linear standard solution was analyzed by high performance gas chromatography to obtain a standard curve graph and a linear equation.

[0051] Table 1. Peak areas of triethylamine detected at different concentrations

[0052]

[0053] Draw a scatter plot and fit the linear calibration curve and linear equation with reference to Table 1. The results show that the linear equation of triethylamine is y=117644x, R 2 =0.9976.

[0054] It is proved that the method of the present invention has a good linear relationship in determining triethylamine.

[0055] S5. Method detection limit

[0056] Sample configuration:

[0057] Accurately weigh 10 mg of triethylamine, 5 g of analytical grade paraformaldehyde, 40 g of methanol, and 0.5 g of 0.5 mol / L sodium hydroxide solution, add them into a flask and stir, set the water bath temperature to 50°C, condense and reflux for 5 minutes until the solution is clear, and filter to obtain sample 1;

[0058] Accurately weigh 5 mg of triethylamine, 5 g of analytical grade paraformaldehyde, 40 g of methanol, and 0.7 g of 1 mol / L sodium hydroxide solution, add them into a flask and stir. Set the water bath temperature to 50°C, condense and reflux for 5 min until the solution is clear, and filter to obtain sample 2.

[0059] Accurately weigh 3 mg of triethylamine, 5 g of analytical grade paraformaldehyde, 40 g of methanol, and 1 g of 1.5 mol / L sodium hydroxide solution, add them into a flask and stir. Set the water bath temperature to 50°C, condense and reflux for 5 min until the solution is clear, and filter to obtain sample 3.

[0060] The gas chromatography conditions were set according to Example 1, and samples 1, 2, and 3 were tested. Each sample was tested 6 times. The specific test results are shown in Table 2 below.

[0061] Table 2. Performance test data of samples

[0062]

[0063] Note: Relative deviation is calculated according to the formula Calculate, where C1 is the sample average value and C0 is the theoretical concentration of triethylamine in the sample.

[0064] Comparative analysis of the test data in Table 2 above shows that when the triethylamine content in the sample is 1 mg / g, the relative deviation is only 2%, and when the triethylamine content in the sample is 0.6 mg / g, the relative deviation reaches 21.7%, indicating that the detection method of the present application can accurately measure the triethylamine content in paraformaldehyde, and its detection concentration reaches 1 mg / g.

[0065] S6. Test sample testing

[0066] The produced paraformaldehyde is used as a test sample;

[0067] Weigh 5g of the paraformaldehyde sample from the prepared paraformaldehyde, add it into a flask with 40g of methanol and 0.5g of 1mol / L sodium hydroxide solution, stir, set the water bath temperature to 50℃, condense and reflux for 5min until the solution is clear, filter, and obtain the test sample. The test results are as follows:

[0068] <Peak table>

[0069] DFID1

[0070] Peak Retention time area high concentration Concentration Unit mark Compound Name 1 2.140 1957 1219 0.007 2 2.213 23731385 11613688 87.776 SV 3 2.676 3206549 817275 11.860 T 4 3.812 96275 38452 0.356 total 27036166 12470635

[0071] The peak position of triethylamine is 3.812, the separation effect is good, the peak is obvious, and it is calculated by the formula: The content of paraformaldehyde in the test sample is 0.1637 mg / g.

[0072] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0073] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0074] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for measuring the content of triethylamine in paraformaldehyde, characterized in that: The following steps are involved: S1. Set up a high performance gas chromatograph according to chromatographic conditions; S2. Prepare the test sample using methanol as solvent; S3, performing gas phase analysis on the test sample using a high performance gas chromatograph with the chromatographic conditions set in step S1; S4. Calculate the content of triethylamine in the sample to be tested according to the calculation formula of the external standard method to obtain the content of triethylamine in the sample to be tested.

2. A detection method for measuring the content of triethylamine in paraformaldehyde according to claim 1, characterized in that: In step S1, the chromatographic conditions are as follows: Chromatographic model: GC2014C; Chromatographic column: SK-5, 0.32mm×30m×0.25um; Injection volume: 1.0uL; Vaporization chamber temperature: 200℃; Injection mode: split flow ratio: 50:1, linear velocity: 26.2 cm / sec; Column temperature: 40°C, hold for 5 minutes, increase the temperature to 200°C at 20°C / min, hold for 2 minutes; Testing room temperature: 250℃.

3. A detection method for measuring the content of triethylamine in paraformaldehyde according to claim 1, characterized in that: The preparation method of the test sample is as follows: 5g of polyformaldehyde sample, 40g of methanol and 0.5-1g of inorganic alkali solution are mixed, condensed and refluxed for 5 minutes under water bath conditions, the solution is clarified, and filtered for sampling.

4. A detection method for measuring the content of triethylamine in paraformaldehyde according to claim 3, characterized in that: The inorganic alkali solution is an aqueous solution of sodium hydroxide, potassium hydroxide or ammonium hydroxide, and the concentration of the inorganic alkali solution is 0.5-1.5 mol / L.

5. A detection method for measuring the content of triethylamine in paraformaldehyde according to claim 1, characterized in that: The calculation formula of external standard method is: Wherein, W is the content; s is the peak area of ​​triethylamine detected by gas chromatography, f is the correction factor, and M is the weight of paraformaldehyde.

6. A detection method for measuring the content of triethylamine in paraformaldehyde according to claim 1, characterized in that: The linear equation of triethylamine is y=117644x.

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