Quality detection method of diacetone acrylamide
By using a 1:2 methanol-water mixed solution with a volume ratio of 1:2 and the HPLC method combined with a gradient elution procedure in bisacetone acrylamide, the complexity and anti-interference problems of detecting the polymerization inhibitor content in the prior art were solved, and the problem of anti-interference was achieved. Fast and accurate quality control improves the precision and stability of inspection.
Patent Information
- Application Number
- CN202411354979.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2024-12-24
AI Technical Summary
In the prior art, the detection method of polymerization inhibitor content in bisacetone acrylamide is complicated to operate and has poor anti-interference ability. Especially during gas chromatography analysis, due to the large difference in boiling points of polymerization inhibitors, it is difficult to analyze and lacks rapidity. Simple quality control method.
The content of polymerization inhibitor was detected by HPLC using a 1:2 mixed solution of methanol-water with a volume ratio of 1:2. Thermo Gold C18 chromatography column was used, and 0.1% phosphoric acid was added to the mobile phase. The gradient elution procedure was optimized, and the detection wavelengths were detected respectively. It is 253nm, 220nm and 240nm, combined with strong shaking, sonication and centrifugation technology to ensure the stability and accuracy of the sample solution.
It realizes rapid and accurate detection of the polymerization inhibitor content in bisacetone acrylamide, provides reliable guarantee of product quality, improves the precision, repeatability and solution stability, reduces impurity interference, and ensures the detection results. reliability.
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Abstract
Description
Technical Field
[0001] The invention relates to a detection method for diacetone acrylamide, and belongs to the technical field of material quality control. Background Art
[0002] Diacetone acrylamide (DAAM) is an important vinyl monomer, which is widely used in new materials such as hair treatment agents, photosensitive resins, adhesives, coatings, resins, etc. In the industrial synthesis of diacetone acrylamide, due to the addition of appropriate inhibitors during the vacuum distillation process, the final product may contain inhibitors. If not properly controlled, it may affect the product quality. Therefore, the content of inhibitors in the final product needs to be controlled.
[0003] Commonly used inhibitors are phenothiazine, p-hydroxyanisole, tetramethyl piperidine nitroxide free radical phosphite triester (inhibitor 705). The inhibitor content in the current diacetone acrylamide product is commonly used in spectrophotometry and gas chromatography, and wherein, spectrophotometry is complex to operate, and anti-interference ability is poor, which limits the application of the method. Because the boiling points of phenothiazine, p-hydroxyanisole and tetramethyl piperidine nitroxide free radical phosphite triester inhibitor differ greatly in diacetone acrylamide, there is certain difficulty in gas chromatography analysis.
[0004] In summary, it is necessary to provide a rapid and simple analysis method for the inhibitor content in diacetone acrylamide to provide a guarantee for product quality control. Summary of the invention
[0005] Purpose of the invention: To provide a method for rapid detection of the content of inhibitor in diacetone acrylamide.
[0006] Technical solution: A method for detecting the content of inhibitor in diacetone acrylamide, wherein the solvent for dissolving the diacetone acrylamide sample is a methanol-water mixed solution with a volume ratio of 1:1.9-2.1, preferably a methanol-water mixed solution with a volume ratio of 1:2.
[0007] The applicant tried to use mobile phase A (methanol-water mixed solution with a volume ratio of 60:40) as the solvent for dissolving diacetone acrylamide samples. It was found that after the prepared test solution was placed at room temperature for about 45 minutes, the original clear solution gradually became turbid and could not be determined by HPLC. When a methanol-water mixed solution with a volume ratio of 1:1.9-2.1 was used as the solvent, the sample solution remained clear even after being placed for 72 hours. Therefore, we chose a methanol-water mixed solution with a volume ratio of 1:2 as the solvent. When the methanol-water mixed solution with a volume ratio exceeding 1:1.9-2.1 was used as the solvent, the sample solution also had varying degrees of turbidity within 1-24 hours after preparation, and could not be determined by HPLC.
[0008] Preferably, the method for detecting the content of polymerization inhibitor in diacetone acrylamide comprises the following steps: (1) Preparation of reference stock solutions: Accurately weigh 20 mg of each of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite tryester reference substances, respectively, and dissolve them in a 1:2 methanol-water mixed solvent until clear, and dilute to 100 ml with a 1:2 methanol-water mixed solvent to obtain standard solutions of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite tryester as reference stock solutions, and store them in a refrigerator away from light; (2) Preparation of diacetone acrylamide test solution: accurately weigh 25.00 g of diacetone acrylamide sample into a beaker, add an appropriate amount of 1:2 methanol-water mixed solvent, shake vigorously for 6 minutes, and then ultrasonicate for 6 minutes. Add 1:2 methanol-water mixed solvent to make the volume to 25 mL, centrifuge at 10,000 rpm for 5 minutes, take the supernatant and filter it through a 0.45 µm filter membrane. The filtrate is used as the test solution; (3) Preparation of the sample solution: Accurately weigh 25.00 g of diacetone acrylamide sample and place it in a 25 ml volumetric flask. Accurately add 1 ml of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide free radical phosphite triester reference substance stock solution, then add 4 ml of a 1:2 methanol-water mixed solvent, shake vigorously for 5 min, and then ultrasonicate for 5 min. Add a 1:2 methanol-water mixed solvent to make up to volume, and then centrifuge at 10,000 rpm for 5 min. Take the supernatant and filter it through a 0.45 µm filter membrane. The filtrate is used as the sample solution. (4) Thermo Gold C18 was used as the chromatographic column, a methanol-water mixture containing 0.1% phosphoric acid in a volume ratio of 60:40 was used as the mobile phase A, and acetonitrile was used as the mobile phase B; the detection wavelengths were 253 nm, 220 nm, and 240 nm, respectively; the sample was injected and gradient eluted according to Table 1. The flow rate was 1.0 ml / min, the column temperature was 30°C, and the injection volume was 80 µl. The contents of phenothiazine, p-hydroxyanisole, and tetramethylpiperidinium nitroxide free radical phosphite triester were calculated respectively.
[0009] Phenothiazine has a maximum absorption at 253 nm and a secondary absorption peak at 320 nm; p-hydroxyanisole has a maximum absorption at 220 nm and a secondary absorption peak at 290 nm; tetramethylpiperidinium nitroxide free radical phosphite triester (inhibitor 705) has a maximum absorption at 240 nm.
[0010] Because the amide structure of the main component diacetone acrylamide is obviously alkaline, the chromatographic peak graphs of the inhibitors phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide free radical phosphite in sample solutions with different diacetone acrylamide contents are significantly different, and the chromatographic peaks are asymmetric in some cases. The experiment found that when 0.1% phosphoric acid was added to the mobile phase, it could be effectively improved and a good effect could be achieved. The retention time of diacetone acrylamide and the inhibitors phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide free radical phosphite was stable and the chromatographic peaks were symmetrical.
[0011] Table 1 Gradient elution program
[0012] Beneficial effects of the present invention: The invention provides a HPLC detection method for diacetone acrylamide, which provides a rapid and accurate quality control method for diacetone acrylamide.
[0013] Embodiment 1: (1) Preparation of reference solution: Accurately weigh 20 mg of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite tryester reference substances, respectively, and dissolve them in a 1:2 methanol-water mixed solvent until clear, and dilute to 100 ml with a 1:2 methanol-water mixed solvent to obtain standard solutions of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite tryester as reference substance stock solutions, and store them in a refrigerator away from light; (2) Preparation of diacetone acrylamide test solution: accurately weigh 25.00 g of diacetone acrylamide sample into a beaker, add an appropriate amount of 1:2 methanol-water mixed solvent, shake vigorously for 6 minutes, and then ultrasonicate for 6 minutes. Add 1:2 methanol-water mixed solvent to make the volume to 25 mL, centrifuge at 10,000 rpm for 5 minutes, take the supernatant and filter it through a 0.45 µm filter membrane. The filtrate is used as the test solution; (3) Preparation of the sample solution: Weigh 25.00 g of diacetone acrylamide sample accurately and place it in a 25 ml volumetric flask. Accurately add 1 ml of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide free radical phosphite triester reference substance stock solutions respectively. Then add 4 ml of a 1:2 methanol-water mixed solvent. Shake vigorously for 5 min. Ultrasonicate for 5 min. Add a 1:2 methanol-water mixed solvent to make up to volume. Centrifuge at 10,000 rpm for 5 min. Filter the supernatant through a 0.45 µm filter membrane. The filtrate is used as the sample solution. (4) Chromatographic conditions: Thermo Gold C18 (4.6×250mm, 5µm) was used as the chromatographic column, a methanol-water mixed solvent with a volume ratio of 60:40 containing 0.1% phosphoric acid was used as the mobile phase A, and acetonitrile was used as the mobile phase B; the detection wavelength was 240nm; gradient elution was performed according to the technical scheme Table 1 of the manual. The flow rate was 1.0 ml / min, the column temperature was 30℃, the injection volume was 80µl, and the test results were recorded; (5) Specificity investigation: 80 µl of blank solvent (methanol-water mixed solution with a volume ratio of 1:2), reference solution, and test solution were accurately measured and injected into the liquid chromatograph. The chromatogram showed that there were no interfering peaks at the peak positions of phenothiazine, p-hydroxyanisole, and tetramethylpiperidinium nitroxide phosphite triester in the blank solvent and the test solution, indicating good method specificity. (6) Precision: The reference solution was sampled and measured six times continuously. The peak areas of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite triester were recorded. The calculated peak area RSDs were 0.8%, 0.5% and 0.6%, respectively. The precisions were good. (7) Repeatability: According to the method for preparing the sample solution of this embodiment, the same batch of diacetone acrylamide (batch number S202401) was used to prepare 6 sample solutions, and the reference solution and the 6 sample solutions were injected respectively. The contents of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite triester were determined in parallel. The results showed that the RSDs of the contents of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite triester in the 6 samples were 1.3%, 1.2% and 1.5%, respectively, indicating good repeatability. (8) Solution stability: According to the method for preparing the sample solution of this example, the sample solution was prepared, and the sample was injected and tested at 0 h, 2 h, 4 h, 8 h, 12 h, and 48 h, respectively. The peak areas of phenothiazine, p-hydroxyanisole, and tetramethylpiperidinium nitroxide free radical phosphite triester were recorded. The peak area RSDs were 0.9%, 1.0%, and 0.9%, respectively, indicating that the solution had good stability within 48 h. (9) Accuracy: Weigh 20 g of diacetone acrylamide sample accurately, a total of 12 portions, and place them in 10 ml volumetric flasks respectively. 3 portions form a group. Add 0.2000 μg, 0.8000 μg, 1.000 μg, and 1.200 μg of reference substance stock solution according to the quantitative limit, low, medium, and high concentrations, respectively. Prepare the solution according to the method of “Preparation of sample solution”, inject and analyze respectively, record the chromatogram, and calculate the recovery rate. The results are shown in Table 2-4.
[0014] Table 2. Phenothiazine accuracy study
[0015] Table 3. Accuracy study of p-hydroxyanisole
[0016] Table 4. Peak accuracy study of tetramethylpiperidinium nitroxide free radical phosphite triester
[0017] Example 2: Sample testing According to the method described in Example 1, diacetone acrylamide test solutions with batch numbers S202401 and S202403 were prepared, and the contents of phenothiazine, p-hydroxyanisole, and tetramethylpiperidinium nitroxide free radical phosphite triester in the diacetone acrylamide test samples were detected respectively according to the HPLC inspection method described in Example 1. The test results are shown in Table 5.
[0018] Table 5. Test results
[0019] Comparative Example 1: The other conditions were the same as in Example 1, except that the initial ratio of mobile phase A was a methanol-water mixed solution with a volume ratio of 70:30, and mobile phase B was acetonitrile. The gradient conditions in Table 6 were used for the operation.
[0020] Table 6. Gradient conditions
[0021] HPLC results showed that under this condition, there were other impurities interfering near the peak positions of the reference substances of p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite triester in the chromatogram of the test solution, which was not conducive to the accurate quantification of the impurities p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite triester. Therefore, the mobile phase ratio needs to be further optimized.
[0022] Control Example 2: Other conditions were the same as in Example 1, except that the initial ratio of mobile phase A was a methanol-water mixed solution with a volume ratio of 50:50, and mobile phase B was acetonitrile. The gradient conditions in Table 1 of the technical solution in the manual were used.
[0023] HPLC results showed that under this condition, there were other impurities interfering near the peak positions of the impurity phenothiazine and hydroxyanisole reference substance in the chromatogram, which was not conducive to the accurate quantification of the impurity phenothiazine and hydroxyanisole. Therefore, the mobile phase ratio needed to be further optimized.
Claims
1. A method for detecting diacetone acrylamide, characterized in that: The solvent for dissolving the diacetone acrylamide sample is a methanol-water mixed solution with a volume ratio of 1:1.9-2.
1.
2. The detection method according to claim 1, characterized in that: The solvent for dissolving the diacetone acrylamide sample is a methanol-water mixed solution with a volume ratio of 1:
2.
3. The detection method according to claim 1, characterized in that: The steps include: (1) Preparation of reference stock solutions: Accurately weigh 20 mg of each of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite tryester reference substances, respectively, and dissolve them in a 1:2 methanol-water mixed solvent until clear, and dilute to 100 ml with a 1:2 methanol-water mixed solvent to obtain standard solutions of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide phosphite tryester as reference stock solutions, and store them in a refrigerator away from light; (2) Preparation of diacetone acrylamide test solution: accurately weigh 25.00 g of diacetone acrylamide sample into a beaker, add an appropriate amount of 1:2 methanol-water mixed solvent, shake vigorously for 6 minutes, and then ultrasonicate for 6 minutes. Add 1:2 methanol-water mixed solvent to make the volume to 25 mL, centrifuge at 10,000 rpm for 5 minutes, take the supernatant and filter it through a 0.45 µm filter membrane. The filtrate is used as the test solution; (3) Preparation of the sample solution: Accurately weigh 25.00 g of diacetone acrylamide sample and place it in a 25 ml volumetric flask. Accurately add 1 ml of phenothiazine, p-hydroxyanisole and tetramethylpiperidinium nitroxide free radical phosphite triester reference substance stock solution, then add 4 ml of a 1:2 methanol-water mixed solvent, shake vigorously for 5 min, and then ultrasonicate for 5 min. Add a 1:2 methanol-water mixed solvent to make up to volume, and then centrifuge at 10,000 rpm for 5 min. Take the supernatant and filter it through a 0.45 µm filter membrane. The filtrate is used as the sample solution. (4) Thermo Gold C18 was used as the chromatographic column, a methanol-water mixture containing 0.1% phosphoric acid in a volume ratio of 60:40 was used as the mobile phase A, and acetonitrile was used as the mobile phase B; the detection wavelengths were 253 nm, 220 nm, and 240 nm, respectively; the sample was injected and gradient eluted according to the table below, and the contents of phenothiazine, p-hydroxyanisole, and tetramethylpiperidinium nitroxide free radical phosphite triester were detected and calculated respectively. Gradient elution procedure:
4. The detection method according to claim 4, characterized in that: The flow rate of the mobile phase in step 4 was 1.0 ml / min.
5. The detection method according to claim 4, characterized in that: Step 4: The column temperature was 30°C.
6. The detection method according to claim 4, characterized in that: The injection volume in step 4 is 80 µl.