Method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin
The static headspace-gas chromatography-mass spectrometry method solves the problem of simultaneous detection of residual monomers in vinyl chloride-vinyl acetate copolymer resin, achieving rapid and accurate quantitative analysis, which is suitable for quality control of complex samples.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUXI HONGHUI NEW MATERIALS TECH
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-28
AI Technical Summary
Existing technologies struggle to rapidly and accurately detect residual vinyl chloride monomer and vinyl acetate monomer in vinyl chloride-vinyl acetate copolymer resins simultaneously. This is especially true in complex sample matrices and in the presence of interfering peaks, which affects the applicability and reliability of the detection results.
A static headspace-gas chromatography-mass spectrometry (HS-GC-MS) method was used to perform quantitative analysis after qualitative identification by mass spectrometry, and a standard curve was established to achieve simultaneous detection of vinyl chloride monomer and vinyl acetate monomer.
Accurate quantification of vinyl chloride monomer and vinyl acetate monomer was achieved in a single test, reducing misjudgment and quantitative deviation caused by co-elution and interfering peaks. The test process is simple and fast, and is suitable for quality control in the production process.
Smart Images
Figure CN121933642A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of analytical chemistry, and in particular to a method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin. Background Technology
[0002] With the widespread application of vinyl chloride-vinyl acetate copolymer resin in industries such as inks, coatings, plastic processing materials, and adhesives, as well as in end-use fields such as paper, food packaging, pharmaceutical packaging, artificial leather, furniture, containers, automobiles, ships, steel structures, and plastic parts, the market has increasingly stringent requirements for its performance stability and environmental safety.
[0003] However, due to factors such as the conversion rate and reaction conditions of the vinyl chloride-vinyl acetate copolymer polymerization reaction, complete conversion of the monomers is difficult to achieve, inevitably resulting in a certain amount of unreacted monomers remaining in the obtained resin. These residual monomers may not only affect the resin's physical properties, chemical stability, and processing consistency, but may also pose potential health and environmental risks.
[0004] Specifically, the common residual monomers in vinyl chloride-vinyl acetate copolymer resins mainly include vinyl chloride monomer and vinyl acetate monomer. Vinyl chloride monomer is a toxic substance, and its residue limits are particularly stringent in sensitive applications such as medical and food packaging. Existing gas chromatography methods for detecting vinyl chloride monomer often suffer from cumbersome sample pretreatment processes and focus primarily on the detection of a single vinyl chloride monomer. Furthermore, the applicability and reliability of the detection results are easily affected when the resin matrix is complex or other volatile components or interfering peaks may be present in the sample. For vinyl acetate monomer, a common method is the chemical analysis of bromine addition to unsaturated double bonds; however, this method suffers from drawbacks such as the volatility of bromine reagents, the potential for side reactions with bromine in the sample introducing interference, and reliance on color changes for judgment, which is prone to subjective errors.
[0005] Therefore, there is an urgent need to establish a simple, rapid, and accurate detection method to simultaneously detect residual monomers in vinyl chloride-vinyl acetate copolymer resin. Summary of the Invention
[0006] To address the challenge of simultaneously detecting residual monomers in vinyl chloride-vinyl acetate copolymer resins using existing methods, this invention discloses a method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resins. The method employs static headspace gas chromatography-mass spectrometry (HS-GC-MS) to first perform qualitative identification of the volatile residual monomers to be tested using mass spectrometry, followed by quantitative analysis based on the qualitative confirmation. This method can simultaneously achieve quantitative determination of vinyl chloride monomers and vinyl acetate monomers in a single detection and can be extended to the detection and monitoring of other residual monomers and volatile components in vinyl chloride-vinyl acetate copolymer resins.
[0007] The technical solution adopted by this invention to solve its technical problem is: A method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin, comprising the following steps: S1: Establishment of standard curve: Prepare an external standard solution of the target monomer with solvent A, place it in a static headspace sampler and detect it using HS-GC-MS to obtain the peak area of the target monomer, and plot the content-peak area standard curve of the target monomer using the external standard method. S2: Sample detection: The vinyl chloride-vinyl acetate copolymer resin to be tested is mixed with solvent A to dissolve it and obtain the test solution. The solution is placed in a static headspace sampler and detected by HS-GC-MS to obtain the peak area of the target monomer. The content of the target monomer in the vinyl chloride-vinyl acetate copolymer resin to be tested is calculated by combining the peak area of the target monomer and the content-peak area standard curve. The target monomers include at least vinyl chloride monomer and vinyl acetate monomer; the chromatographic column of the HS-GC-MS is a DB-1701 capillary gas chromatographic column.
[0008] Optionally, solvent A is N,N-dimethylacetamide (DMAC).
[0009] Optionally, in step S2, the sample amount of the vinyl chloride-vinyl acetate copolymer resin is 0.1 g, and the amount of N,N-dimethylacetamide added is 1 mL.
[0010] Optionally, the external standard solution is prepared according to the following method: Using solvent A as the diluent, a mixed standard stock solution containing vinyl chloride monomer and vinyl acetate monomer was serially diluted to prepare external standard solutions with multiple concentration gradients; and the concentration gradients of the external standard solutions were 0.1 μg / mL, 0.3 μg / mL, 0.5 μg / mL, 0.7 μg / mL, 0.9 μg / mL, 1.1 μg / mL and 1.3 μg / mL.
[0011] Optionally, the headspace conditions of the static headspace sampler are set as follows: equilibrium temperature 80℃, quantitative loop temperature 120℃, transfer line temperature 150℃, equilibrium time 20min, pressurization time 0.5min, and injection time 1min.
[0012] Optionally, the gas chromatography injection conditions of the HS-GC-MS are as follows: injection port temperature 230℃, injection mode split mode, split ratio 10:1, carrier gas helium, and constant flow rate 1.6 mL / min.
[0013] Optionally, the column oven temperature program of the HS-GC-MS is as follows: the column oven temperature is initially 40°C and held for 3 minutes, then increased to 120°C at 10°C / min and held for 1 minute, and then increased to 230°C at 20°C / min and held for 3 minutes.
[0014] The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1 is characterized in that the mass spectrometry conditions of the HS-GC-MS are: EI ion source full scan mode, mass transfer line temperature 260℃, and mass-to-charge ratio scan range of 35-300.
[0015] Optionally, the content-peak area standard curve of the target monomer is specifically as follows: The regression equation for the external standard curve of vinyl chloride monomer is: y = 38627.369552x - 3.100002; The regression equation for the external standard curve of vinyl acetate monomer is: y = 62076.369002x - 5.12076; In the formula, y is the peak area of the target monomer in the chromatogram, and x is the content of the target monomer in the vinyl chloride-vinyl acetate copolymer resin to be tested, in μg / g.
[0016] Optionally, the content of the target monomer is calculated using the following formula: Monomer content (μg / g) = Standard solution concentration (μg / mL) / Standard peak area × Target monomer peak area × 1 mL / 0.1 g.
[0017] The present invention has the following beneficial effects: This invention employs a HS-GC-MS coupled method, first performing qualitative identification of the volatile residual monomers to be analyzed by mass spectrometry, and then conducting quantitative analysis based on the qualitative confirmation. This effectively reduces misjudgments and quantitative deviations caused by co-elution or interfering peaks, even in cases with complex sample matrices, diverse residual components, and the potential presence of unknown interfering substances. Furthermore, this method features a simple detection process, fast analysis speed, and convenient operation. It can simultaneously achieve quantitative determination of vinyl chloride monomer and vinyl acetate monomer in a single detection and can be extended to the detection and monitoring of other residual monomers and volatile components in vinyl chloride-vinyl acetate resins. It is suitable for quality control in production processes and has significant advantages. Attached Figure Description
[0018] Figure 1 The total ion chromatogram of the sample in Example 1; Figure 2 The mass spectrum of vinyl chloride obtained in Example 1; Figure 3 The mass spectrum of vinyl acetate obtained in Example 1 is shown below. Figure 4 The standard curve of vinyl chloride established for Example 1; Figure 5 The standard curve of vinyl acetate established in Example 1 is shown. Detailed Implementation
[0019] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0020] During the production of vinyl chloride-vinyl acetate copolymer resin, various unreacted monomers and other volatile components often remain in the resin due to factors such as polymerization conversion rate, reaction conditions, and fluctuations in post-processing. These residues may not only degrade the physicochemical properties and processing stability of the resin but also pose environmental and health risks. Because the production sample matrix is complex and the composition is variable, traditional gas chromatography detection methods for vinyl chloride typically rely on retention time for judgment. In the presence of unknown volatile interfering substances or peak overlap, it is difficult to accurately identify whether the target peak is interfered with. Furthermore, the bromine addition chemical analysis method for vinyl acetate is easily affected by factors such as reagent volatilization, side reactions, and the subjectivity of color interpretation, thus introducing significant analytical errors.
[0021] To address the challenge of simultaneously detecting residual monomers in vinyl chloride-vinyl acetate copolymer resins using existing methods, this invention provides a method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resins, comprising the following steps: S1: Establishment of standard curve: Prepare an external standard solution of the target monomer with solvent A, place it in a static headspace sampler and detect it using HS-GC-MS to obtain the peak area of the target monomer, and plot the content-peak area standard curve of the target monomer using the external standard method. S2: Sample detection: The vinyl chloride-vinyl acetate copolymer resin to be tested is mixed with solvent A to dissolve it and obtain the test solution. The solution is placed in a static headspace sampler and detected by HS-GC-MS to obtain the peak area of the target monomer. The content of the target monomer in the vinyl chloride-vinyl acetate copolymer resin to be tested is calculated by combining the peak area of the target monomer and the content-peak area standard curve. The target monomers include at least vinyl chloride monomer and vinyl acetate monomer; the chromatographic column of the HS-GC-MS is a DB-1701 capillary gas chromatographic column.
[0022] Specifically, solvent A is preferably N,N-dimethylacetamide; and preferably, the amount of vinyl chloride-vinyl acetate copolymer resin sampled in step S2 is 0.1 g, and the amount of N,N-dimethylacetamide added is 1 mL.
[0023] The preferred method for preparing the external standard solution of this invention is as follows: using N,N-dimethylacetamide as a diluent, a mixed standard stock solution containing vinyl chloride monomer and vinyl acetate monomer is serially diluted to obtain external standard solutions with multiple concentration gradients; and the concentration gradients of the external standard solutions are 0.1 μg / mL, 0.3 μg / mL, 0.5 μg / mL, 0.7 μg / mL, 0.9 μg / mL, 1.1 μg / mL and 1.3 μg / mL.
[0024] Furthermore, the preferred headspace conditions for the static headspace sampler of the present invention are set as follows: equilibrium temperature 80°C, quantitative loop temperature 120°C, transfer line temperature 150°C, equilibrium time 20 min, pressurization time 0.5 min, and injection time 1 min.
[0025] The preferred gas chromatography injection conditions for HS-GC-MS in this invention are: injection port temperature 230℃, injection mode split mode, split ratio 10:1, carrier gas helium, and constant flow rate 1.6 mL / min.
[0026] The preferred column oven temperature program of the present invention for HS-GC-MS is as follows: the column oven temperature is initially 40°C and held for 3 min, then increased to 120°C at 10°C / min and held for 1 min, and then increased to 230°C at 20°C / min and held for 3 min.
[0027] The preferred mass spectrometry conditions for HS-GC-MS in this invention are: EI ion source full scan mode, mass transfer line temperature 260℃, and mass-to-charge ratio scan range of 35-300.
[0028] The preferred target monomer content-peak area standard curve of this invention is as follows: The regression equation for the external standard curve of vinyl chloride monomer is: y = 38627.369552x - 3.100002; The regression equation for the external standard curve of vinyl acetate monomer is: y = 62076.369002x - 5.12076; In the formula, y is the peak area of the target monomer in the chromatogram, and x is the content of the target monomer in the vinyl chloride-vinyl acetate copolymer resin to be tested, in μg / g.
[0029] The preferred content of the target monomer in this invention is calculated using the following formula: standard solution concentration (μg / mL) / standard peak area × target monomer peak area × 1 mL / 0.1 g.
[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.
[0031] Example 1 This embodiment provides a method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin, comprising the following steps: S1: Using DMAC as the diluent, a mixed standard solution of vinyl chloride and vinyl acetate, each with a concentration of 1000 mg / L, was serially diluted to prepare external standard solutions with concentrations of 0.1 μg / mL, 0.3 μg / mL, 0.5 μg / mL, 0.7 μg / mL, 0.9 μg / mL, 1.1 μg / mL, and 1.3 μg / mL, respectively. S2: Take the external standard solutions of each concentration gradient mentioned above, fill them into headspace sample vials and seal them. Place them in a static headspace sampler and perform detection using HS-GC-MS. Integrate the corresponding chromatographic peaks of vinyl chloride monomer and vinyl acetate monomer to obtain the standard peak area of the target monomer in each standard solution. Plot a content-peak area standard curve with the target monomer content as the x-axis and the standard peak area as the y-axis. The standard curves for vinyl chloride and vinyl acetate are shown below. Figure 4 and Figure 5 As shown; The regression equation for the standard curve of target monomer content versus peak area is as follows: The regression equation for the external standard curve of vinyl chloride monomer is: y = 38627.369552x - 3.100002; The regression equation for the external standard curve of vinyl acetate monomer is: y = 62076.369002x - 5.12076; In the formula, y is the peak area of the target monomer in the chromatogram, and x is the content of the target monomer in the vinyl chloride-vinyl acetate copolymer resin to be tested, in μg / g.
[0032] S3: Take 0.1g of vinyl chloride-vinyl acetate copolymer resin into a 20ml headspace sample vial, add 1ml of analytical grade DMAC, and dissolve the sample completely to obtain the test solution. Then seal the headspace sample vial for later use.
[0033] S4: Place the test solution obtained in step S3 into a static headspace sampler and detect it using HS-GC-MS; The instrument configuration is as follows: Agilent 7697A headspace sampler (HS), Agilent 7890B gas chromatograph (GC), and Agilent 5977B mass spectrometer (MS). The specific testing conditions are as follows: Chromatographic column: DB-1701 capillary gas chromatograph column; Headspace conditions (HS): Equilibrium temperature 80 ℃, equilibrium time 20 min; quantitative loop temperature 120 ℃; transfer line temperature 150 ℃; pressurization time 0.5 min; injection time 1 min; Gas chromatography (GC) conditions: Injector temperature 230 °C; split injection, split ratio 10:1; carrier gas helium, constant flow rate 1.6 mL / min; column oven temperature program: initial 40 °C, hold for 3 min; increase to 120 °C at 10 °C / min, hold for 1 min; then increase to 230 °C at 20 °C / min, hold for 3 min. Mass spectrometry conditions (MS): EI ion source, full scan mode; mass transfer line temperature 260 ℃; mass-to-charge ratio scan range 35-300.
[0034] Under the above conditions, the total ion chromatogram (TIC) of the vinyl chloride resin sample can be obtained, such as... Figure 1 As shown.
[0035] S5: Perform spectral library search and matching on the target peaks in the sample, and confirm them in conjunction with characteristic ions: Vinyl chloride: retention time TR(VCM) = 3.551 min, characteristic ion m / z = 62, mass spectrum shown below. Figure 2 ; Vinyl acetate: retention time TR(VAM) = 7.05 min, characteristic ion m / z = 43, mass spectrum shown below. Figure 3 .
[0036] S6: The content-peak area standard curve established in step S2 ( Figure 4 , Figure 5The target peak area of the target monomer is obtained by integrating the target peak in the chromatogram obtained in step S4, which was qualitatively confirmed in step S5.
[0037] In this embodiment, the target monomer content is preferably calculated using the external standard ratio method, and the calculation formula is as follows: Monomer content (μg / g) = Standard solution concentration (μg / mL) / Standard peak area × Target monomer peak area × 1 mL / 0.1 g; Wherein, “standard solution concentration / standard peak area × target monomer peak area” is used to convert the peak area of the target monomer into the equivalent concentration (μg / mL) of the target monomer in the sample solution; “×1 mL / 0.1 g” is used to convert the equivalent concentration into the mass content (μg / g) in the resin according to the sample preparation volume (1 mL) and sampling amount (0.1 g) in this embodiment.
[0038] The vinyl chloride content and vinyl acetate content in the sample were calculated using the above formula.
[0039] To verify the linearity of the external standard response relationship and the reliability of the calculation results, the sample peak area can also be substituted into the standard curve regression equation described in step S2 for comparison calculation. The results are consistent with or basically consistent with the results calculated by the external standard ratio method.
[0040] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin, characterized in that, Includes the following steps: S1: Establishment of standard curve: Prepare an external standard solution of the target monomer with solvent A, place it in a static headspace sampler and detect it using HS-GC-MS to obtain the peak area of the target monomer, and plot the content-peak area standard curve of the target monomer using the external standard method. S2: Sample detection: The vinyl chloride-vinyl acetate copolymer resin to be tested is mixed with solvent A to dissolve it and obtain the test solution. The solution is placed in a static headspace sampler and detected by HS-GC-MS to obtain the peak area of the target monomer. The content of the target monomer in the vinyl chloride-vinyl acetate copolymer resin to be tested is calculated by combining the peak area of the target monomer and the content-peak area standard curve. The target monomers include at least vinyl chloride monomer and vinyl acetate monomer; the chromatographic column of the HS-GC-MS is a DB-1701 capillary gas chromatographic column.
2. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1, characterized in that, Solvent A is N,N-dimethylacetamide.
3. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1, characterized in that, In step S2, the sample amount of the vinyl chloride-vinyl acetate copolymer resin is 0.1 g, and the amount of N,N-dimethylacetamide added is 1 mL.
4. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1, characterized in that, The external standard solution was prepared according to the following method: Using solvent A as the diluent, a mixed standard stock solution containing vinyl chloride monomer and vinyl acetate monomer was serially diluted to prepare external standard solutions with multiple concentration gradients; and the concentration gradients of the external standard solutions were 0.1 μg / mL, 0.3 μg / mL, 0.5 μg / mL, 0.7 μg / mL, 0.9 μg / mL, 1.1 μg / mL and 1.3 μg / mL.
5. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1, characterized in that, The headspace conditions of the static headspace sampler are set as follows: equilibrium temperature 80℃, quantitative loop temperature 120℃, transfer line temperature 150℃, equilibrium time 20min, pressurization time 0.5min, and injection time 1min.
6. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1, characterized in that, The gas chromatography injection conditions for the HS-GC-MS are as follows: injection port temperature 230℃, injection mode split mode, split ratio 10:1, carrier gas helium, and constant flow rate 1.6 mL / min.
7. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1, characterized in that, The column oven temperature program of the HS-GC-MS is as follows: the column oven temperature is initially 40℃ and held for 3 min, then increased to 120℃ at 10℃ / min and held for 1 min, and then increased to 230℃ at 20℃ / min and held for 3 min.
8. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1, characterized in that, The mass spectrometry conditions for the HS-GC-MS are: EI ion source full scan mode, mass transfer line temperature 260℃, and mass-to-charge ratio scan range of 35-300.
9. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 1, characterized in that, The content-peak area standard curve of the target monomer is specifically as follows: The regression equation for the external standard curve of vinyl chloride monomer is: y = 38627.369552x - 3.100002; The regression equation for the external standard curve of vinyl acetate monomer is: y = 62076.369002x - 5.12076; In the formula, y is the peak area of the target monomer in the chromatogram, and x is the content of the target monomer in the vinyl chloride-vinyl acetate copolymer resin to be tested, in μg / g.
10. The method for detecting residual monomers in vinyl chloride-vinyl acetate copolymer resin according to claim 9, characterized in that, The content of the target monomer is calculated using the following formula: Monomer content (μg / g) = Standard solution concentration (μg / mL) / Standard peak area × Target monomer peak area × 1 mL / 0.1 g.