Method for detecting succinic anhydride hydrolysis reaction rate using high performance liquid chromatography

Abstract

This invention relates to the field of succinic anhydride hydrolysis reaction detection technology, and discloses a method for detecting the succinic anhydride hydrolysis reaction rate using high performance liquid chromatography (HPLC). The method includes the following steps: (1) diluting the succinic anhydride hydrolysis reaction product with acetonitrile to obtain the test solution; (2) analyzing the test solution using HPLC, with a diode array detector, a reversed-phase column, and a mobile phase of a mixture of acetonitrile and water, and quantifying using the external standard method. The method provided by this invention utilizes ultra-high performance liquid chromatography (UHPLC) to simultaneously determine the content of succinic anhydride and succinic acid in the reaction solution, and has the advantages of rapid detection, simple method, and good repeatability.

Description

Technical Field

[0001] This invention relates to the field of succinic anhydride hydrolysis reaction detection technology, and specifically to a method for detecting the succinic anhydride hydrolysis reaction rate using high performance liquid chromatography. Background Technology

[0002] Succinic acid, as an important organic chemical raw material and intermediate, is widely used in industries such as synthetic plastics, rubber, and pharmaceuticals. The main methods for preparing succinic acid include catalytic hydrogenation, paraffin oxidation, electrochemical methods, and bio-fermentation. Catalytic hydrogenation, using maleic anhydride as a raw material, is the most widely used industrial method for succinic acid synthesis worldwide. The reaction begins with maleic anhydride and hydrogen gas, undergoing catalytic hydrogenation to obtain succinic anhydride, which is then hydrolyzed to prepare succinic acid.

[0003] The hydrolysis of succinic acid is exothermic, and the products succinic acid and succinic anhydride have significantly different properties. The reaction rate is typically monitored using GB / T264-83, "Determination of Acid Value of Petroleum Products." This method involves extracting the acidic component from the sample with boiling ethanol, then titrating with a potassium hydroxide ethanol standard solution using Basic Blue B as an indicator. However, this method is complex, time-consuming, and unsuitable for real-time monitoring of the hydrolysis reaction. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned problems in the prior art and to provide a method for detecting the hydrolysis reaction rate of succinic anhydride using high performance liquid chromatography. This method utilizes ultra-high performance liquid chromatography to simultaneously determine the content of succinic anhydride and succinic acid in the reaction solution, and has the advantages of rapid detection, simple method and good repeatability.

[0005] To achieve the above objectives, the present invention provides a method for detecting the hydrolysis rate of succinic anhydride using high-performance liquid chromatography, the method comprising the following steps:

[0006] (1) The product of succinic anhydride hydrolysis reaction was diluted with acetonitrile to prepare the test solution;

[0007] (2) The test solution was analyzed by high performance liquid chromatography. The detector was a diode array detector, the chromatographic column was a reversed phase column, the mobile phase was a mixture of acetonitrile and water, and the external standard method was used for quantification.

[0008] This invention employs ultra-high performance liquid chromatography (UPLC) combined with specific diluents and mobile phases to detect the hydrolysis rate of succinic anhydride. It can effectively detect the concentrations of succinic acid and succinic anhydride in the reaction solution and thus obtain the reaction rate. The method of this invention not only has high accuracy, repeatability, and stability, but also has a short processing time, which can complete the hydrolysis reaction rate detection within 1.5 minutes. Therefore, the rapid monitoring of the hydrolysis reaction rate of succinic anhydride using UPLC has significant guiding significance for optimizing hydrolysis process conditions. Attached Figure Description

[0009] Figure 1 This is an ultra-high performance liquid chromatogram of the test solution according to a preferred embodiment of the present invention.

[0010] Figure 2 This is a curve showing the change in concentrations of succinic anhydride and succinic acid in the test solution of Example 1 of the present invention.

[0011] Figure 3 This is a curve showing the concentration changes of succinic anhydride and succinic acid in the test solution of Example 2 of the present invention.

[0012] Figure 4 This is a curve showing the change of peak area integral of succinic anhydride and succinic acid in the test solution of Example 4 of the present invention with the standing time. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] This invention provides a method for detecting the hydrolysis rate of succinic anhydride using high performance liquid chromatography, the method comprising the following steps:

[0015] (1) The product of succinic anhydride hydrolysis reaction was diluted with acetonitrile to prepare the test solution;

[0016] (2) The test solution was analyzed by high performance liquid chromatography. The detector was a diode array detector, the chromatographic column was a reversed phase column, the mobile phase was a mixture of acetonitrile and water, and the external standard method was used for quantification.

[0017] According to the present invention, preferably, the volume ratio of the succinic anhydride hydrolysis product to acetonitrile in the test solution is 1:5-30. During the succinic anhydride hydrolysis reaction, the concentrations of succinic acid and succinic anhydride in the reaction solution are relatively high, making them prone to precipitation after sampling and direct injection, which can exceed the detector's range. Therefore, it is necessary to dilute the reaction solution. Limiting the dilution factor within the above-mentioned range can prevent column clogging and sample concentration exceeding the detector's range.

[0018] According to the present invention, a diode array detector can be used to perform continuous wavelength scanning in the range of 200-400nm. However, in order to improve the accuracy of detection, it is preferable that the scanning wavelength of the diode array detector is 205-230nm (e.g., any value between 205nm, 210nm, 215nm, 220nm, 225nm, 230nm or higher). Considering both sensitivity and anti-interference, it is more preferable that the wavelength is 210-220nm, and even more preferably, the wavelength is 210nm.

[0019] According to the present invention, preferably, the reversed-phase column is a polar-modified octadecylsilane-bonded chromatographic column.

[0020] According to the present invention, preferably, the volume ratio of acetonitrile to water in the mobile phase is 10-30:70-90, for example 10:90, 15:85, 20:80, 25:75, 30:70, etc., and more preferably 20-25:80-75. When the volume ratio of acetonitrile to water is limited to the above range, baseline separation of the two components can be achieved with a shorter separation time (e.g., ...). Figure 1 However, when the volume ratio of acetonitrile is >30%, succinic acid and succinic anhydride cannot be separated at baseline; when the volume ratio of acetonitrile is <10%, succinic acid and succinic anhydride exhibit tailing, and the separation time becomes longer.

[0021] According to the present invention, preferably, a standard curve is prepared before analyzing the test solution using high-performance liquid chromatography. The process of preparing the standard curve includes:

[0022] A. Prepare a succinic anhydride standard stock solution with a concentration of 15-25 mg / mL (such as 15 mg / mL, 18 mg / mL, 20 mg / mL, 22 mg / mL or 25 mg / mL or any value between the above ranges) using acetonitrile as a solvent;

[0023] B. Prepare a succinic acid standard stock solution with a concentration of 30 mg / mL (e.g., 20 mg / mL, 25 mg / mL, 28 mg / mL, 30 mg / mL, or 35 mg / mL or any value between the above ranges) using a mixture of acetonitrile and water in a volume ratio of 1:(3-5) (1:3, 1:4 or 1:5) as the solvent.

[0024] C. The mother liquors from steps A and B are serially diluted and detected by liquid chromatography. Plot the standard curves of succinic anhydride in the concentration range of 0.1-20 mg / mL and the standard curves of succinic acid in the concentration range of 0.1-30 mg / mL with peak area as the ordinate and concentration as the abscissa.

[0025] The liquid chromatography conditions include:

[0026] Chromatographic column: UPLC HSS T3 column, particle size 1.5-2.5μm, dimensions (0.8-1.2)mm × (80-120)mm, or other similar columns.

[0027] The volume ratio of the mobile phase is: acetonitrile:water = 10⁻³⁰:90⁻⁷⁰ (volume ratio).

[0028] Mobile phase flow rate: 0.3-0.5 mL / min

[0029] Detection wavelength: 205-230nm

[0030] Injection volume: 0.5-3 μL;

[0031] D. The regression equation is calculated as follows:

[0032] Y 丁二酸酐 =260218C 丁二酸酐 -3557, linear correlation coefficient R 2 =0.9998

[0033] Y 丁二酸 =214889C 丁二酸 +70796, linear correlation coefficient R 2 =0.9991

[0034] Among them, Y 丁二酸酐 The integral peak area of ​​succinic anhydride, C 丁二酸酐 Y represents the concentration of succinic anhydride. 丁二酸 The integral peak area of ​​succinic anhydride, C 丁二酸 This refers to the concentration of succinic acid.

[0035] According to the present invention, preferably, the peak areas corresponding to succinic anhydride and succinic acid in the high performance liquid chromatogram of the test solution are substituted into their respective regression equations to calculate the concentrations of succinic anhydride and succinic acid in the test solution. The hydrolysis reaction is considered to be complete when the concentration of succinic anhydride in the solution (test solution) is <0.1 mg / mL.

[0036] According to the present invention, preferably, the injection volume of the test solution is 0.5-3 μL.

[0037] According to the present invention, preferably, the total flow rate of the mobile phase is 0.3-0.5 mL / min relative to a chromatographic column with a specification of 1 mm (ID) × 100 mm.

[0038] According to the present invention, preferably, the column temperature of the chromatographic column is 30-45°C.

[0039] According to the present invention, preferably, the analysis of the test solution by high performance liquid chromatography can be completed within 1.5 minutes.

[0040] In this invention, there are no particular restrictions on the conditions of the hydrolysis reaction corresponding to the hydrolysis rate of the succinic anhydride to be tested. For example, the hydrolysis reaction temperature can be 30-70℃, and the amount of succinic anhydride used relative to 100g of water can be 10-30g.

[0041] The present invention will be described in detail below through embodiments. In the following embodiments,

[0042] Experimental instruments and chromatographic conditions:

[0043] The Waters H-class ultra-high performance liquid chromatograph, Waters 2996 diode array detector (PDA), and the control and recording of the chromatographic separation system are completed by the Waters Empower3.0 workstation.

[0044] The chromatographic column used was a Waters ACQUITY UPLC HSS T3 column with an average particle size of 1.8 μm, a column size of 1 mm (ID) × 100 mm, and a column temperature of 35 ℃.

[0045] Succinic anhydride and succinic acid (analytical grade, >99.5%).

[0046] Acetonitrile (HPLC grade).

[0047] In the experiment, both the mobile phase and the solution were made of high-purity water.

[0048] External standard curve creation

[0049] Accurately weigh 2000 mg of succinic anhydride into a 100 mL volumetric flask and dilute to volume with acetonitrile to obtain a 20 mg / mL succinic anhydride standard stock solution. Accurately weigh 3000 mg of succinic acid into a 100 mL volumetric flask and dilute to volume with an acetonitrile:water solution at a ratio of 1:4 (v / v) to obtain a 30 mg / mL succinic acid standard stock solution. Dilute both stock solutions to the required concentrations with acetonitrile and inject them separately. The mobile phase composition was acetonitrile:water = 20:80 (v / v), the mobile phase flow rate was 0.3 mL / min, the detection wavelength was 210 nm, and the injection volume was 1 μL. Plot a curve of peak area versus concentration (mg / mL), and the regression equation is:

[0050] Y 丁二酸酐 =260218C 丁二酸酐 -3557, R² = 0.9998

[0051] Y 丁二酸 =214889C 丁二酸 +70796, R 2 =0.9991,

[0052] In addition, when the signal-to-noise ratio S / N = 3, the detection limits for succinic anhydride and succinic acid were 0.002 mg / mL and 0.006 mg / mL, respectively.

[0053] Example 1

[0054] This example illustrates the use of high-performance liquid chromatography (HPLC) to detect the hydrolysis rate of succinic anhydride.

[0055] The hydrolysis reaction conditions for succinic anhydride were as follows: reaction temperature 35℃, 10.45 g of succinic anhydride, and 100 g of water. As the reaction proceeded, at 0 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, and 35 min, 100 μL of the reaction solution was taken from the reactor and transferred to a sample vial. Then, 900 μL of acetonitrile was added and mixed thoroughly, and this mixture was used as the analyte for injection. The injection volume was 1 μL. The mobile phase composition was acetonitrile:water = 20:80 (volume ratio), the mobile phase flow rate was 0.3 mL / min, and the detection wavelength was 210 nm. The chromatographic peaks of succinic anhydride and succinic acid in the obtained liquid chromatogram were integrated, and the concentration changes of succinic anhydride and succinic acid in the reaction solution were calculated by substituting the peaks into the external standard curve regression equation. (See figure). Figure 2 .

[0056] Example 2

[0057] This example illustrates the use of high-performance liquid chromatography (HPLC) to detect the hydrolysis rate of succinic anhydride.

[0058] The hydrolysis reaction conditions for succinic anhydride were as follows: reaction temperature 60℃, succinic anhydride 29.87g, and water 100g. As the reaction proceeded, at 0 min, 2 min, 4 min, 6 min, 8 min, and 10 min, 100 μL of the reaction solution was taken from the reactor and added to a sample vial. Then, 900 μL of acetonitrile was added and mixed thoroughly before being injected as the analyte. The injection volume was 1 μL. The mobile phase composition was acetonitrile:water = 20:80 (volume ratio), the mobile phase flow rate was 0.3 mL / min, and the detection wavelength was 210 nm. The concentration changes of succinic anhydride and succinic acid in the reaction solution were calculated by integrating the peaks of succinic anhydride and succinic acid in the obtained liquid chromatogram and substituting them into the external standard curve regression equation. (See figure). Figure 3 .

[0059] Example 3

[0060] This embodiment is used to test the repeatability of the high-performance liquid chromatography method for detecting the hydrolysis rate of succinic anhydride in this invention.

[0061] The test solutions with different reaction times in Example 2 were injected 5 times in accordance with the method in Example 2. The succinic anhydride and succinic acid chromatographic peaks in the obtained liquid chromatograms were integrated, and the relative standard deviation (RSD) of the integrated area was calculated. The results are shown in Table 1.

[0062] Table 1

[0063] Sampling time 0min 2min 4min 6min 8min 10min Succinic anhydride RSD% 0.53 0.47 0.78 1.14 2.35 3.02 Succinic acid RSD% 1.26 0.88 0.74 0.65 0.71 0.53

[0064] The repeatability RSD of this method for succinic anhydride is <3.02%, and the repeatability RSD for succinic acid is <1.26%, indicating that the method of detecting the hydrolysis reaction rate of succinic anhydride using high performance liquid chromatography has good repeatability.

[0065] Example 4

[0066] This embodiment is used to test the stability of the succinic anhydride hydrolysis reaction rate detection method of the present invention using high performance liquid chromatography.

[0067] The hydrolysis reaction conditions for succinic anhydride were: reaction temperature 60℃, succinic anhydride 29.87g, and water 100g. As the reaction proceeded, at the 2nd minute, 100μL of the reaction solution was transferred to a sample vial, and 900μL of acetonitrile was added and mixed thoroughly. The time after mixing was recorded as 0 min. After injection, the integrated peak areas of succinic anhydride and succinic acid were recorded. The sample was then allowed to stand for 10 min, 20 min, 30 min, 60 min, and 120 min sequentially before injection, and the integrated peak areas of succinic anhydride and succinic acid were recorded. The results are shown below. Figure 4 .

[0068] The results showed that the contents of succinic anhydride and succinic acid in the solution did not change significantly within 60 minutes as the storage time increased. The experiment showed that the method has good stability and the detection can be completed within 60 minutes after the sample is collected.

[0069] Comparative Example 1

[0070] The comparative example was prepared according to GB / T264-83 "Determination of Acid Value of Petroleum Products" to determine the succinic acid content in the reaction solution at 0 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, and 35 min in Example 1. The results are shown in Table 2. The results of the two methods are consistent, indicating that the method provided by the present invention is accurate and reliable.

[0071] Table 2

[0072]

[0073] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for detecting the hydrolysis rate of succinic anhydride using high performance liquid chromatography, characterized in that, The method includes the following steps: (1) The product of succinic anhydride hydrolysis reaction was diluted with acetonitrile to prepare the test solution; (2) The test solution was analyzed by high performance liquid chromatography. The detector was a diode array detector, the chromatographic column was a reversed phase column, the mobile phase was a mixture of acetonitrile and water, and the external standard method was used for quantification. The volume ratio of succinic anhydride hydrolysis product to acetonitrile in the test solution is 1:5-30; the scanning wavelength of the diode array detector is 210-220 nm; and the volume ratio of acetonitrile to water in the mobile phase is 20-25:80-75. Before analyzing the test solution using high-performance liquid chromatography (HPLC), a standard curve is prepared. The process of preparing the standard curve includes: A. Prepare a standard stock solution of succinic anhydride with a concentration of 15-25 mg / mL using acetonitrile as solvent; B. Prepare a succinic acid standard stock solution with a concentration of 25-35 mg / mL using a mixture of acetonitrile and water in a volume ratio of 1:(3-5) as the solvent; C. The mother liquors from steps A and B are serially diluted and detected by liquid chromatography. Plot the standard curves of succinic anhydride in the concentration range of 0.1-20 mg / mL and the standard curves of succinic acid in the concentration range of 0.1-30 mg / mL with peak area as the ordinate and concentration as the abscissa. The liquid chromatography conditions include: Chromatographic column: UPLC HSS T3 column, particle size 1.5-2.5μm, dimensions (0.8-1.2) mm × (80-120) mm. The volume ratio of the mobile phase is: acetonitrile:water = 20-30:80-70. Mobile phase flow rate: 0.3-0.5 mL / min Detection wavelength: 205-230nm Injection volume: 0.5-3 μL; D. The regression equation is calculated as follows: Y 丁二酸酐 = 260218C 丁二酸酐 - 3557, linear correlation coefficient R 2 = 0.9998, Y 丁二酸 =214889C 丁二酸 +70796, linear correlation coefficient R 2 =0.9991, R 2 The goodness of fit of the linear regression equation; Among them, Y 丁二酸酐 The integral peak area of ​​succinic anhydride, C 丁二酸酐 Y represents the concentration of succinic anhydride. 丁二酸 The integral peak area of ​​succinic anhydride, C 丁二酸 This refers to the concentration of succinic acid. The peak areas corresponding to succinic anhydride and succinic acid in the high performance liquid chromatogram of the test solution were substituted into their respective regression equations to calculate the concentrations of succinic anhydride and succinic acid in the test solution. The hydrolysis reaction was defined as complete when the concentration of succinic anhydride in the test solution was <0.1 mg / mL.

2. The method according to claim 1, wherein, The flow rate of the mobile phase is 0.3-0.5 mL / min relative to a chromatographic column with dimensions of 1 mm × 100 mm.

3. The method according to claim 1, wherein, The column temperature of the chromatographic column is 30-45℃.

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