A rapid screening method for solvent residue in food contact packaging materials

Abstract

The application discloses a kind of fast screening method of solvent residual quantity in food contact packaging material, sample is sent into gas chromatograph by headspace sampler and separates out the gas to be measured, and the gas to be measured is detected using hydrogen flame ion detector, and the chromatogram of sample is obtained;Add mixed standard intermediate liquid of known content in blank matrix to obtain the standard reference sample of the limited concentration to be measured, and the peak area of methyl acetate, benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene is measured respectively;By comparing the sum of the peak area of all detected substances in sample chromatogram with the chromatographic peak area of methyl acetate in standard reference sample, judge whether the total amount of residual solvent meets the limit requirement, and by comparing the peak area of benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene in sample with the peak area of corresponding substance in standard reference sample, judge whether each benzene solvent meets the limit requirement.

Description

Technical Field

[0001] This invention relates to a detection method, and more particularly to a rapid screening method for solvent residue in food contact packaging materials. Background Technology

[0002] In recent years, to meet the requirements of oxygen barrier, moisture protection, heat resistance, quality preservation, and environmental protection, food packaging materials have undergone technological improvements, gradually evolving from single-layer films to multi-layer composite films. However, the printing, lamination, and coating processes of food composite packaging materials involve the use of inks and adhesives, which introduce various organic solvents (such as benzene, toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, n-butanol, isopropanol, and propylene glycol methyl ether acetate). These solvents may migrate into the food during packaging, storage, and transportation, affecting food quality and posing a threat to human health. Therefore, national food safety standards impose strict limits on the total amount of residual solvents and the amount of benzene-based solvents.

[0003] Currently, the main methods for detecting residual solvents include headspace / gas chromatography-mass spectrometry (HCGC-MS) and headspace / gas chromatography (GC). In gas chromatography, static headspace gas chromatography (GC) is more advantageous than dynamic headspace gas chromatography (GC) and direct injection, and has become the preferred method for residual solvent detection. However, food contact composite packaging materials include various materials (such as paper-plastic, aluminum-plastic, plastic-plastic, paper-aluminum-plastic, etc.). These composite packaging materials use a wide variety of solvents during production. Furthermore, the types of solvents tested in various standards for total solvent residue detection need to be determined based on the actual solvents used in production. Therefore, when it is impossible to accurately obtain information on all solvents used, the total solvent residue, including the types of solvents, cannot be determined, thus making it impossible to ascertain the product's compliance. Furthermore, multiple product standards impose strict limits on benzene, toluene, ethylbenzene, xylene, and other benzene-based solvents in food contact composite packaging materials. Existing testing methods require the separate preparation of standard curves for detecting total solvent residues and benzene-based solvent residues, which is time-consuming in terms of solution preparation and instrument testing. Therefore, establishing a rapid screening method for both total solvent residues and benzene-based solvent residues is of great significance for the hygienic performance testing of food composite packaging materials, improving testing efficiency, and saving energy and reducing consumption. Summary of the Invention

[0004] The purpose of this invention is to provide a rapid screening method for detecting solvent residues in food contact packaging materials that is fast and accurate.

[0005] The technical solution to achieve the purpose of this invention is: a rapid screening method for solvent residue in food contact packaging materials, wherein the sample is sent into a gas chromatograph through a headspace sampler to separate the gas to be tested, and the gas to be tested is detected by a hydrogen flame ionization detector to plot a test curve; a standard curve is established by adding a mixed standard intermediate liquid with standard content to a blank matrix; by comparing the test curve of the sample with the standard curve, it is determined whether the total amount of residual solvent and benzene solvents exceed the standard.

[0006] The mixed standard intermediate solution includes ethyl acetate, benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene.

[0007] The headspace sampler operating parameters are as follows:

[0008] Headspace constant temperature: 80℃;

[0009] Injection loop temperature: 90℃;

[0010] Transmission line temperature: 100℃;

[0011] Headspace equilibration time: 30 min;

[0012] Ring balancing time: 0.05 min;

[0013] Pressurization time: 0.2 min;

[0014] Injection time: 1 min.

[0015] The operating parameters of the gas chromatograph are:

[0016] The chromatographic column is 30 mm long, 0.32 mm in inner diameter, and 0.25 μm thick.

[0017] Temperature program: Initial temperature 50℃, hold for 30 minutes, increase temperature to 70℃ at 10℃ / min and hold for 1 minute, increase temperature to 160℃ at 12℃ / min and hold for 1 minute, run for 2 minutes;

[0018] Inlet temperature: 200℃;

[0019] Injection mode: split injection, split ratio 15:1;

[0020] Detector temperature: 300℃;

[0021] Carrier gas: nitrogen, flow rate 1.0 mL / min;

[0022] Hydrogen flow rate: 30 mL / min;

[0023] Air flow rate: 400 mL / min;

[0024] Tail-blown flow rate: 25 mL / min.

[0025] The sample was prepared by means of a single-sided area of ​​100 cm². 2 The sample is rolled up and placed in the sample vial of the headspace sampler. The headspace vial is then sealed, and the sample is successfully prepared.

[0026] The method for establishing the standard curve is as follows: a mixed standard intermediate solution is injected into a headspace vial containing a blank matrix and then analyzed by a gas chromatograph; the injected mixed standard intermediate solution includes 50 μg methyl acetate, 0.1 μg benzene, 2 μg toluene, 2 μg ethylbenzene, 2 μg o-xylene, 2 μg m-xylene, and 2 μg p-xylene; the blank matrix has a single-sided area of ​​100 cm². 2 .

[0027] The mixed standard intermediate solution was prepared by mixing methyl acetate standard solution, benzene standard solution, and a mixed benzene standard solution. Take 5 mL of 20000 mg / L methyl acetate standard stock solution, 100 μL of 2000 mg / L benzene standard stock solution, and 2 mL of a mixed standard stock solution of toluene, ethylbenzene, and three xylenes (each with a concentration of 2000 mg / L) into a 10 mL volumetric flask. Add N,N-dimethylformamide to the mark and mix well.

[0028] The standard solution of methyl acetate has a mass concentration of 20000 mg / L. The preparation process is as follows: accurately weigh 200 mg of methyl acetate into a 10 mL volumetric flask, dissolve it with N,N-dimethylformamide and dilute to the mark, and mix well.

[0029] The benzene standard solution has a mass concentration of 2000 mg / L. The preparation process is as follows: accurately weigh 20 mg of benzene into a 10 mL volumetric flask, dissolve it with N,N-dimethylformamide and dilute to the mark, then mix well.

[0030] The mass concentration of each component in the benzene mixed standard solution is 2000 mg / L. The preparation process is as follows: accurately weigh 20 mg of toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene into a 10 mL volumetric flask, dissolve them with N,N-dimethylformamide and dilute to the mark, and mix well.

[0031] By adopting the above technical solution, the present invention has the following beneficial effects:

[0032] (1) This invention uses methyl acetate in a standard reference sample with a limited concentration as a reference substance. Without using other toxic or harmful solvents, the method allows for rapid screening of whether the total residual solvent in the sample meets the limit requirements. This is achieved by analyzing the sample using gas chromatography to obtain a test curve, which is then compared with the standard curve. Simultaneously, it screens for the restricted use of benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene. When screening samples that meet the limit requirements, this rapid screening method for total residual solvent has advantages such as accurate test results, reduced use of toxic and harmful solvents, cost savings, and ease of operation. It is suitable for batch testing tasks in inspection and testing institutions and enterprise product quality control.

[0033] (2) The present invention uses a headspace sampler for injection. By heating, volatile components are volatilized from the sample matrix and reach equilibrium in the gas and liquid phases. The top gas is directly extracted for chromatographic analysis, thereby examining the composition and content of volatile components in the sample. This eliminates the lengthy and cumbersome sample pretreatment process, avoids interference from organic solvents in the analysis, reduces contamination of the chromatographic column and injection port, and makes injection convenient and accurate, thus improving the accuracy of the test.

[0034] (3) The present invention uses gas chromatography to separate the sample and uses a hydrogen flame ionization detector to detect the separated gas. The detection results are accurate and can perform precise qualitative and quantitative analysis of the sample.

[0035] (4) The headspace sampler of the present invention has appropriate parameter selection. The higher temperature and appropriate flow time ensure that the sample will not condense under these parameters, reduce the loss of volatile substances, obtain the maximum sensitivity and precision, and ensure detection accuracy.

[0036] (5) The parameters of the gas chromatograph of the present invention are appropriately selected. Under these parameter conditions, the sample can be completely vaporized, the peak shape is normal, the response is high, and the repeatability is good. Attached Figure Description

[0037] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0038] Figure 1 This is a chromatogram of the GC-FID standard mixed solution of the present invention. Detailed Implementation

[0039] See Figure 1 The rapid screening method for solvent residue in food contact packaging materials in this embodiment is as follows.

[0040] The sample preparation process is as follows: the single-sided area of ​​the sample is 100 cm². 2The sample is placed in a vacuum drying oven and dried at 90℃ for 24 hours. After drying, it is stored in a sealed container for later use. The sample is then rolled up and placed in a headspace sampler vial. The vial is then sealed. The sample preparation is now complete. When preparing the sample, if the sample is printed with ink, the area with the largest ink distribution should be selected to ensure that the sample represents the worst quality condition of the batch.

[0041] The method for establishing the standard curve is as follows: A mixed standard intermediate solution is injected into a headspace vial containing a blank matrix and then analyzed by a gas chromatograph. The mixed standard intermediate solution is prepared by mixing methyl acetate standard solution, benzene standard solution, and a mixed benzene standard solution. Take 5 mL of methyl acetate standard stock solution (20000 mg / L), 100 μL of benzene standard stock solution (2000 mg / L), and 2 mL of a mixed standard stock solution of toluene, ethylbenzene, and three xylenes (all 2000 mg / L) in a 10 mL volumetric flask. Add N,N-dimethylformamide to the mark and mix well.

[0042] The standard solution of methyl acetate has a mass concentration of 20000 mg / L. The preparation process is as follows: accurately weigh 200 mg of methyl acetate into a 10 mL volumetric flask, dissolve it with N,N-dimethylformamide and dilute to the mark, and mix well.

[0043] The benzene standard solution has a mass concentration of 2000 mg / L. The preparation process is as follows: accurately weigh 20 mg of benzene into a 10 mL volumetric flask, dissolve it with N,N-dimethylformamide and dilute to the mark, then mix well.

[0044] The mass concentration of each component in the benzene mixed standard solution is 2000 mg / L. The preparation process is as follows: accurately weigh 20 mg of toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene into a 10 mL volumetric flask, dissolve them with N,N-dimethylformamide and dilute to the mark, and mix well.

[0045] The injected mixed standard intermediate solution included 50 μg methyl acetate, 0.1 μg benzene, 2 μg toluene, 2 μg ethylbenzene, 2 μg o-xylene, 2 μg m-xylene, and 2 μg p-xylene. The blank matrix had a single-sided area of ​​100 cm². 2 .

[0046] To improve the accuracy of solvent detection, the sample was injected into a gas chromatograph via a headspace sampler to separate the analyte gas. A flame ionization detector was used to detect the analyte gas, and a test curve was plotted. A standard curve was established by adding a mixed standard intermediate solution with the standard content to a blank matrix. By comparing the sample test curve with the standard curve, it was determined whether the total residual solvent and benzene solvent exceeded the limit. Peak areas within the retention time range were compared: when the sum of the peak areas of all chromatographic peaks in the sample with retention times between methyl acetate and N,N-dimethylformamide and peak areas greater than the benzene peak area was less than or equal to the methyl acetate peak area in the mixed standard working solution, the total residual solvent in the sample was <5 mg / m³. 2 When the peak area of ​​benzene in the sample is less than or equal to the peak area of ​​benzene in the mixed standard working solution, the residual amount of benzene in the sample is less than 0.01 mg / m³. 2 When the sum of the peak areas of other benzene solvents in the sample is less than the peak area of ​​toluene in the mixed standard working solution, the residual amounts of toluene, ethylbenzene, and xylene in the sample are less than 0.2 mg / m³. 2 .

[0047] To detect and compare the total amount of residual solvents and benzene-based solvents, a standard curve was plotted using a mixed standard intermediate solution, which included ethyl acetate, benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene.

[0048] To facilitate sample injection, a headspace sampler is used. The operating parameters for the headspace sampler are as follows:

[0049] Headspace constant temperature: 80℃.

[0050] Injection loop temperature: 90℃.

[0051] Transmission line temperature: 100℃.

[0052] Headspace equilibration time: 30 min.

[0053] Ring balancing time: 0.05 min.

[0054] Pressurization time: 0.2 min.

[0055] Injection time: 1 min.

[0056] To enhance testing accuracy, gas chromatography was used to detect the samples, and appropriate parameters were set to further improve precision. The operating parameters of the gas chromatograph are as follows:

[0057] The chromatographic column is 30 mm long, 0.32 mm in inner diameter, and 0.25 μm thick.

[0058] Temperature rise program: Initial temperature 50℃, hold for 30 minutes, increase temperature to 70℃ at 10℃ / min and hold for 1 minute, increase temperature to 160℃ at 12℃ / min and hold for 1 minute, run for 2 minutes.

[0059] Inlet temperature: 200℃.

[0060] Injection mode: split injection, split ratio is 15:1.

[0061] Detector temperature: 300℃.

[0062] Carrier gas: nitrogen, flow rate 1.0 mL / min.

[0063] Hydrogen flow rate: 30 mL / min.

[0064] Air flow rate: 400 mL / min.

[0065] Tail-blown flow rate: 25 mL / min.

[0066] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapid screening method for solvent residue in food contact packaging materials, characterized in that: The sample was fed into a gas chromatograph via a headspace sampler to separate the analyte gas, which was then detected using a flame ionization detector. Plot a test curve; establish a standard curve by adding a mixed standard intermediate solution with standard content to a blank matrix; determine whether the total residual solvent and benzene solvent exceed the standard by comparing the sample test curve with the standard curve; the mixed standard intermediate solution is prepared by mixing methyl acetate standard solution, benzene standard solution, and benzene mixed standard solution; determine the total residual solvent in the sample by comparing the peak areas within the retention time range: when the sum of the peak areas of all chromatographic peaks in the sample whose retention time is between that of methyl acetate and N,N-dimethylformamide and whose peak area is greater than that of benzene is less than or equal to the peak area of ​​methyl acetate in the mixed standard working solution, then the total residual solvent in the sample is <5 mg / m³. 2 When the peak area of ​​benzene in the sample is less than or equal to the peak area of ​​benzene in the mixed standard working solution, the residual amount of benzene in the sample is less than 0.01 mg / m³. 2 When the sum of the peak areas of other benzene solvents in the sample is less than the peak area of ​​toluene in the mixed standard working solution, the residual amounts of toluene, ethylbenzene, and xylene in the sample are less than 0.2 mg / m³. 2 The methyl acetate standard solution has a mass concentration of 20000 mg / L, the benzene standard solution has a mass concentration of 2000 mg / L, and the mass concentration of each component in the benzene mixed standard solution is 2000 mg / L. The injected mixed standard intermediate solution includes 50 μg methyl acetate, 0.1 μg benzene, 2 μg toluene, 2 μg ethylbenzene, 2 μg o-xylene, 2 μg m-xylene, and 2 μg p-xylene. The blank matrix has a single-sided area of ​​100 cm². 2 .

2. The rapid screening method for solvent residue in food contact packaging materials according to claim 1, characterized in that: The headspace sampler operating parameters are as follows: Headspace constant temperature: 80℃; Injection loop temperature: 90℃; Transmission line temperature: 100℃; Headspace equilibration time: 30 min; Ring balancing time: 0.05 min; Pressurization time: 0.2 min; Injection time: 1 min.

3. The rapid screening method for solvent residue in food contact packaging materials according to claim 1, characterized in that: The operating parameters of the gas chromatograph are: The chromatographic column is 30 mm long, 0.32 mm in inner diameter, and 0.25 μm thick. Temperature program: Initial temperature 50℃, hold for 30 minutes, increase temperature to 70℃ at 10℃ / min and hold for 1 minute, increase temperature to 160℃ at 12℃ / min and hold for 1 minute, run for 2 minutes; Inlet temperature: 200℃; Injection mode: split injection, split ratio 15:1; Detector temperature: 300℃; Carrier gas: nitrogen, flow rate 1.0 mL / min; Hydrogen flow rate: 30 mL / min; Air flow rate: 400 mL / min; Tail-blown flow rate: 25 mL / min.

4. The rapid screening method for solvent residue in food contact packaging materials according to claim 1, characterized in that: The sample was prepared by means of a single-sided area of ​​100 cm². 2 The sample is rolled up and placed in the sample vial of the headspace sampler. The headspace vial is then sealed, and the sample is successfully prepared.

5. The rapid screening method for solvent residue in food contact packaging materials according to claim 1, characterized in that: The method for establishing the standard curve is as follows: inject the mixed standard intermediate solution into a headspace vial containing a blank matrix. The sample was sent to a gas chromatograph for detection, and a standard curve was plotted.

6. The rapid screening method for solvent residue in food contact packaging materials according to claim 1, characterized in that: The preparation process of the methyl acetate standard solution is as follows: accurately weigh 200 mg of methyl acetate into a 10 mL volumetric flask, dissolve it with N,N-dimethylformamide and dilute to the mark, then mix well.

7. The rapid screening method for solvent residue in food contact packaging materials according to claim 1, characterized in that: The preparation process of the benzene standard solution is as follows: accurately weigh 20 mg of benzene into a 10 mL volumetric flask, dissolve it with N,N-dimethylformamide and dilute to the mark, then mix well.

8. The rapid screening method for solvent residue in food contact packaging materials according to claim 1, characterized in that: The preparation process of the benzene mixed standard solution is as follows: accurately weigh 20 mg of toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene into a 10 mL volumetric flask, dissolve them with N,N-dimethylformamide and dilute to the mark, and mix well.

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