Determination method for additive migration in fresh agricultural product package

Abstract

The invention belongs to the technical field of chemical analysis and detection, and relates to a method for measuring the migration amount of an additive in a fresh agricultural product package. Comprising an additive migration experiment, sample treatment and instrument analysis. Aiming at the problem of additive migration in the fresh agricultural product package, food simulants are adopted and different temperature and time conditions are combined, and migration of the additive in the fresh agricultural product package is systematically researched. And the migration condition of the additive in the simulant is analyzed by utilizing GC-MS. Specifically, the invention establishes an effective method for measuring the migration amount of the additive in the fresh agricultural product package, the influence of different temperatures and time on the migration of the additive in the package is considered, and the migration rule is investigated. The method has the advantages of simple operation, high sensitivity, good accuracy and the like, is suitable for rapid detection of additive migration in various fresh agricultural product packages, and provides reliable technical support for food safety supervision.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical analysis and detection, and relates to a method for determining the migration of additives in fresh agricultural product packaging. Background Art

[0002] Fruits and vegetables are essential for promoting healthy growth and development of the human body. Fresh produce packages (FPPs) play an important role in protecting fruits and vegetables from a range of environmental impacts. However, in order to meet the specific performance requirements of packaging materials (such as flexibility, flame retardancy and antioxidant properties), a variety of functional additives are usually added during the production process. A large number of studies have confirmed that during the use of packaging, these additives can easily migrate into food and eventually be ingested by consumers, endangering human health.

[0003] In the current field of food packaging safety, research on the migration of harmful additives mainly focuses on the migration of packaging materials into liquid foods / food simulants (such as water, beverages, oils, different concentrations of ethanol, etc.). The relevant research has been relatively mature and has formed a relatively complete analysis method and evaluation system. However, there are relatively few studies on the migration of additives from packaging materials to solid foods (such as fruits, vegetables, etc.), especially the systematic research on influencing factors and migration amount is still obviously insufficient.

[0004] Polyurethane foam packaging has become one of the most widely used FPPs in the market due to its excellent elasticity and thermal insulation properties. In addition, the use conditions of this type of packaging span different temperatures, time, etc., which will have a multi-faceted impact on the migration of additives. This further increases public concern about the risk of additive exposure. However, there is currently no specific research on the migration of additives in this type of packaging. Therefore, establishing an effective measurement method to clarify the migration of additives in this type of packaging material is a key issue that needs to be addressed urgently.

[0005] At present, the determination methods of additives reported in domestic and foreign literature are mainly gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). Among them, GC-MS is mostly used to analyze volatile and semi-volatile substances, while LC-MS is mostly used to analyze non-volatile substances. Compared with non-volatile substances, volatile and semi-volatile substances are more likely to migrate into food, so their potential risks are higher. Summary of the invention

[0006] To solve the above problems, the present invention provides a method for determining the migration of additives in fresh agricultural product packaging, which involves the entire workflow of additive migration experiment, sample processing and instrument analysis. Aiming at the problem of additive migration in FPPs, the present invention uses food simulants and combines different temperature and time conditions to systematically study the migration of additives in polyurethane foam packaging. The migration of additives in the simulants is analyzed by GC-MS.

[0007] The technical solution of the present invention:

[0008] A method for determining the migration of additives in fresh agricultural product packaging comprises the following steps:

[0009] Step (1) Selection and pretreatment of food simulants

[0010] According to the properties of fresh agricultural products (such as fat content, water content, acidity and alkalinity, etc.), the present invention selects poly (2,6-diphenyl-p-phenylene ether) (Tenax) as a food simulant of fresh agricultural products, and washes and dries it to obtain a pre-treated solid food simulant. Tenax can simulate low-fat solid food.

[0011] Before using Tenax (particle size of 60-80 mesh, pore size of 200 nm), it was first cleaned using an accelerated solvent extractor (ASE) and ethyl acetate solvent. The extraction conditions of ASE were set as follows: temperature 100°C, pressure 1500 psi, heating for 5 minutes, 2 static cycles, each static time of 10 minutes, purge time of 120 seconds, and flushing volume of 60%. After cleaning, the solid simulant was placed in a vacuum drying oven, dried at 80°C for 6 hours, and then cooled to room temperature to obtain the pretreated solid food simulant.

[0012] Step (2) Migration and accumulation of additives in fresh agricultural product packaging

[0013] The fresh agricultural product packaging material is covered with a certain surface area on a certain mass of the simulant pretreated in step (1) to migrate, wherein the coating amount of Tenax per unit area is 4 g / dm 2 The migration temperature range is 5℃~40℃, and the migration time is 12~240h. After the migration is completed, the packaging material is separated from Tenax, and the migrated Tenax is ultrasonically extracted using ethyl acetate solvent. A substitute is added before extraction, and the supernatant after extraction is enriched using a nitrogen blowing concentrator. The enriched sample is transferred to an injection vial, fixed to volume, and an internal standard solution is added. It is stored at at least -20℃ for further analysis.

[0014] The surrogate is an isotope marker of the target additive, and the internal standard is hexamethylbenzene, and the spiked amounts of the two are the same. The concentrations of the surrogate and the target additive in the sample must be within the linear range of the standard curve.

[0015] Step (3) Preparation of standard solution

[0016] Preparation of standard stock solution: dilute the original standard of the target additive with n-hexane solution to a fixed volume, and finally obtain a standard stock solution with a concentration of 1000 μg / mL, which is stored in a refrigerator at 4–8°C.

[0017] Preparation of mixed standard working solution: Dilute the standard stock solution with n-hexane to make a 10 μg / mL mixed standard working solution.

[0018] Preparation of series of standard solutions: According to the content of target additives in the sample to be tested, the gradient concentration range of the series of standard solutions is set to 20-5000 ng / mL, and the gradient concentration can be set to 20, 50, 100, 200, 500, 1000, 2000, 5000 ng / mL. When the sample concentration exceeds the calibration range, the sample is diluted and further analyzed.

[0019] Step (4) Gas chromatography-mass spectrometry (GC-MS) analysis of additives

[0020] The same amount of internal standard is added to the series of standard solutions prepared in step (3), and then analyzed using GC-MS to establish a calibration curve of the response ratio (peak area) and concentration of the target analyte and the internal standard; then, the migration sample treated in step (2) is quantified for the target additive.

[0021] The analytical conditions of GC-MS were as follows: the chromatographic separation was performed using a SH-Rxi-5sil column (30 m × 0.25 mm × 0.25 μm) in selected ion monitoring (SIM) mode. A 1.0 μL sample was automatically injected in splitless mode. The GC oven temperature program was set as follows: initial temperature 60 °C, maintained for 1 min, then increased to 220 °C at a rate of 10 °C / min, maintained for 1 min, then increased to 250 °C at a rate of 5 °C / min, maintained for 1 min, and finally increased to 300 °C at a rate of 10 °C / min, maintained for 5 min. The carrier gas was helium with a flow rate of 1.2 mL / min and a constant linear velocity. An electron impact ionization source (EI) was used with an ion source temperature of 250 °C and an ionization voltage of 70 eV.

[0022] Beneficial effects of the present invention:

[0023] The present invention uses Tenax as a food simulant, combines different temperature and time conditions to conduct additive migration experiments on FPPs, and uses GC-MS to analyze the migration of additives in the simulant. The main purpose is to establish an effective method for determining the migration amount of additives in FPPs, consider the influence of different temperatures and times on the migration of additives in this type of packaging, and investigate the migration rules.

[0024] The experiment found that within the temperature and time range studied, polyurethane foam sponge sheets released 11 target additives into food simulants. Temperature had a significant effect on the migration of additives. As the temperature increased from 5°C to 40°C, the migration of packaging materials in Tenax showed a significant increasing trend. The research results provide a scientific basis for the safe use of this type of food packaging material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a basic flow chart of the method of the present invention.

[0026] Figure 2 It is the extracted ion chromatogram of the standard solution of 11 target additives.

[0027] Figure 3 This is the matrix spike recovery result graph of 11 target additives.

[0028] Figure 4 It is a bar graph showing the effect of migration temperature on the amount of additive migration in foam sponge sheets.

[0029] Figure 5 It is a trend chart showing the effect of migration time on the migration of additives in foam sponge sheets. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is described in detail below in conjunction with the technical solution.

[0031] The basic process of the method for determining the migration of additives in fresh agricultural product packaging of the present invention is as follows: Figure 1 As shown, the specific embodiments and measurement results are as follows:

[0032] Example 1 Selection of food simulants and migration conditions

[0033] According to the properties of fresh fruits and vegetables (such as fat content, water content, acidity and alkalinity, etc.), the present invention selects Tenax as a food simulant for fresh fruits and vegetables. Tenax can simulate low-fat solid food. The particle size of the selected Tenax [poly (2,6-diphenylene oxide)] is 60-80 mesh and the pore size is 200nm.

[0034] Since different usage scenarios may affect the migration amount of additives, this experiment focuses on the migration rules of additives under different conditions. Therefore, different temperature and time conditions were set. The experimental design is as follows: Under the condition of a constant migration time of 240 hours, the temperature is controlled at 5℃, 25℃ and 40℃ respectively, and a temperature gradient experiment is carried out; at the same time, under a constant temperature of 25℃, the migration time is controlled at 12h, 24h, 72h, 120h, 168h and 240h respectively, and a time gradient experiment is carried out.

[0035] The specific implementation steps of the migration experiment are as follows: Fresh agricultural product packaging example: polyurethane foam sponge sheet; First, cut the foam sponge material into 5×5cm 2 The samples (three parallel samples for each group) were prepared and weighed accurately. Subsequently, a single layer of foam sponge was covered on the evenly dispersed Tenax, and the amount of Tenax was set to 4g / dm per unit surface area of ​​the packaging material. 2 Next, the treated specimens were completely wrapped in aluminum foil and placed in a petri dish. Finally, the petri dish was transferred to an artificial climate incubator to conduct the migration experiment under the preset time and temperature conditions.

[0036] Example 2 Treatment of Migration Samples

[0037] After the migration experiment is completed, the packaged sample is separated from the simulant. To detect the presence of additives in Tenax, the simulant is transferred to a 30mL glass centrifuge tube and 100ng of a mixture of isotope-labeled standards is added. Subsequently, 5mL of ethyl acetate is added to the centrifuge tube, ultrasonic extraction is performed for 30 minutes, and centrifugation is performed at 3000rpm for 10 minutes. The supernatant is taken, filtered through a 0.22μm polytetrafluoroethylene needle filter, and transferred to a clean glass bottle. Repeat the above extraction process, combine the extracts, evaporate to near dryness under a gentle stream of high-purity nitrogen, and finally adjust the volume to 0.5mL. Before instrumental analysis, 100ng of hexamethylbenzene is added as an internal standard.

[0038] Example 3 GC-MS analysis

[0039] A GC-MS analysis method for 11 additives was established, and the method quantitative limits, spike recovery rates and matrix effects of the 11 additives were determined. Finally, the target additives in the migration samples were quantified based on the internal standard method. The specific test steps are as follows:

[0040] The detailed information of the test compounds (including target analytes, surrogates, and internal standards) is shown in Table 1.

[0041] Table 1 Summary of chemical names, abbreviations, CAS numbers, quantitative and qualitative separations of each analyte

[0042]

[0043] The GC-MS analysis conditions are as follows:

[0044] The instrument was operated in selected ion monitoring (SIM) mode, and chromatographic separation was performed using an SH-Rxi-5sil column (30m×0.25mm×0.25μm). The sample was automatically injected in splitless mode with an injection volume of 1.0μL. The GC oven temperature program was set as follows: initial temperature 60℃, maintained for 1 minute; then heated to 220℃ at a rate of 10℃ / min, maintained for 1 minute; then heated to 250℃ at a rate of 5℃ / min, maintained for 1 minute; finally heated to 300℃ at a rate of 10℃ / min, maintained for 5 minutes. The carrier gas was high-purity helium with a flow rate of 1.2mL / min and a constant linear velocity. The MS part used an EI ionization source with an ion source temperature of 250℃ and an ionization voltage of 70eV.

[0045] Establishment of standard curve: 11 target analytes were prepared into standard solutions with different concentration gradients, i.e. 20, 50, 100, 200, 500, 1000, 2000, 5000 ng / mL. The concentrations of the surrogate and internal standard in the standard solution were both 200 ng / mL. The standard solution was analyzed by GC-MS to establish a linear curve between the response and concentration. The linear regression coefficient (R 2 ) The results are shown in Table 2. R 2 The linear relationship is between 0.998 and 0.999, and the extracted ion chromatograms of the standard solutions (1000 ng / mL) of the 11 target substances are shown in the figure. Figure 2 As shown in the figure: a is the extracted ion chromatogram of EHA; b is the extracted ion chromatogram of TEP; c is the extracted ion chromatogram of DMP; d is the extracted ion chromatogram of TBP; e is the extracted ion chromatogram of TCPP; f is the extracted ion chromatogram of DIBP; g is the extracted ion chromatogram of DBP; h is the extracted ion chromatogram of DBS; i is the extracted ion chromatogram of DBEP; j is the extracted ion chromatogram of DEHP; k is the extracted ion chromatogram of UV-328.

[0046] Method quantification limit: To determine the quantification limit of the method during the migration process, a target standard solution with a concentration of 20 ng / mL was added to the treated sample matrix. For compounds not detected in the program blank, the quantification limit was determined by the concentration at a signal-to-noise ratio (S / N) of 10; for compounds detected in the program blank, the quantification limit was calculated based on 10 times the standard deviation of the program blank.

[0047] Matrix effect: Calculate the matrix effect by comparing the response of the spiked sample (minus the response of the unspiked sample) with the response of the standard solution of the same concentration. The spiked amount of the target analyte was 100 ng / mL.

[0048] The method quantification limits and matrix effect results of the 11 target additives are shown in Table 2. The matrix effect ranged from 68.1% to 109.0%, which met the analysis requirements.

[0049] Matrix spike recovery: The target compound and surrogate were spiked into the cleaned and dried Tenax matrix at a spike level of 100 ng / mL. The spike recovery of the target compound was calculated for three replicate samples. The results are shown in Figure 3 shown.

[0050] Table 2 Instrumental analysis performance, method quantification limit and matrix effect of 11 target additives

[0051]

[0052] Example 4 Effect of Temperature on Migration of Additives in Foam Sponge Sheets

[0053] The foam sponge was subjected to migration experiments for 240 hours at migration temperatures of 5°C, 25°C and 40°C. After the migration experiment, the sample was processed and finally analyzed by GC-MS to obtain the migration amount of the corresponding target additive, such as Figure 4 As shown. With the increase of temperature, the migration amount of the 11 target additives in the foam sponge sheet all showed a trend of gradually increasing, especially at a temperature of 40°C, the migration amount of the additives in the simulant increased sharply, such as triethyl phosphate (TEP). During the migration time of 240 hours, the migration amount at 40°C increased from 15.02μg to 27.77μg at 5°C.

[0054] Example 5 Effect of time on additives in foam sponge sheets

[0055] The migration time of the foam sponge sheet was controlled at 12h, 24h, 72h, 120h, 168h and 240h at 25℃. Figure 5 As shown in the figure: a is the extracted ion chromatogram of EHA; b is the extracted ion chromatogram of TEP; c is the extracted ion chromatogram of DMP; d is the extracted ion chromatogram of TBP; e is the extracted ion chromatogram of TCPP; f is the extracted ion chromatogram of DIBP; g is the extracted ion chromatogram of DBP; h is the extracted ion chromatogram of DBS; i is the extracted ion chromatogram of DBEP; j is the extracted ion chromatogram of DEHP; k is the extracted ion chromatogram of UV-328.

[0056] When the migration time increases from 12h to 120h, the migration amount of 11 additives in the foam sponge sheet increases significantly. Taking di(2-ethylhexyl) phthalate as an example, at 40℃, the migration amount of 240h is 10 times that of 12h. The above results show that extending the time can increase the migration amount of additives.

Claims

1. A method for determining the migration of additives in fresh agricultural product packaging, characterized in that: The steps include: Step (1) Selection and pretreatment of food simulants According to the properties of fresh agricultural products, poly (2,6-diphenyl-p-phenylene ether) Tenax is selected as a food simulant of fresh agricultural products, and the pretreated solid food simulant is obtained by washing and drying. Step (2) Migration and accumulation of additives in fresh agricultural product packaging The fresh agricultural product packaging material is covered with a certain surface area on a certain mass of the simulant pretreated in step (1) to migrate, wherein the coating amount of Tenax per unit area is 4 g / dm 2 ; The migration temperature range is 5°C-40°C, and the migration time is 12-240h; after the migration is completed, the packaging material is separated from the Tenax, and the migrated Tenax is ultrasonically extracted using ethyl acetate solvent, and a substitute is added before extraction. The supernatant after extraction is enriched using a nitrogen blow concentrator, and the enriched sample is transferred to an injection vial, fixed to volume and added with an internal standard solution, and stored at least -20°C for further analysis; Step (3) Preparation of standard solution Preparation of standard stock solution: dilute the original standard of the target additive with n-hexane solution to a fixed volume; Preparation of mixed standard working solution: dilute the standard stock solution with n-hexane to make a mixed standard working solution; Preparation of a series of standard solutions: according to the content of the target additive in the sample to be tested, the gradient concentration of the series of standard solutions is set; when the sample concentration exceeds the calibration range, the sample is diluted and further analyzed; step (4) gas chromatography-mass spectrometry analysis of the additive The same amount of internal standard is added to the series of standard solutions prepared in step (3), and then analyzed using GC-MS to establish a calibration curve of the response ratio and concentration of the target analyte and the internal standard; then, the migration sample treated in step (2) is quantified for the target additive.

2. The method for determining the migration of additives in fresh agricultural product packaging according to claim 1, characterized in that: In step (1), the particle size of the Tenax is 60-80 meshes and the pore size is 200 nm; before using Tenax, it is first cleaned using an accelerated solvent extractor ASE and ethyl acetate solvent; the extraction conditions of ASE are set as follows: temperature 100°C, pressure 1500psi, heating for 5 minutes, 2 static cycles, each static time is 10 minutes, purge time is 120 seconds, and flushing volume is 60%; after cleaning, the solid simulant is placed in a vacuum drying oven, dried at 80°C for 6 hours, and then cooled to room temperature to obtain a pretreated solid food simulant.

3. The method for determining the migration of additives in fresh agricultural product packaging according to claim 1, characterized in that: In step (2), the surrogate is an isotope labeled target additive, and the internal standard is hexamethylbenzene, and the amounts of both are the same; the concentrations of the surrogate and the target additive in the sample must be within the linear range of the standard curve.

4. The method for determining the migration of additives in fresh agricultural product packaging according to claim 1, characterized in that: In step (3), Preparation of standard stock solution: dilute the original standard of the target additive with n-hexane solution to a fixed volume, and finally obtain a standard stock solution with a concentration of 1000 μg / mL, which is stored in a refrigerator at 4–8°C; Preparation of mixed standard working solution: dilute the standard stock solution with n-hexane to make a 10 μg / mL mixed standard working solution; Preparation of a series of standard solutions: According to the content of the target additive in the sample to be tested, the gradient concentration range of the series of standard solutions is set to 20-5000 ng / mL.

5. The method for determining the migration of additives in fresh agricultural product packaging according to claim 1, characterized in that: In step (4), The analysis conditions of GC-MS are as follows: operate in selected ion monitoring mode, and use SH-Rxi-5sil column for chromatographic separation; take 1.0 μL sample and automatically inject it in splitless mode; the GC oven temperature program is set as follows: initial temperature 60°C, hold for 1 min, then increase to 220°C at a rate of 10°C / min, hold for 1 min, then increase to 250°C at a rate of 5°C / min, hold for 1 min, and finally increase to 300°C at a rate of 10°C / min, hold for 5 min; the carrier gas is helium, the flow rate is 1.2 mL / min, and the linear velocity is constant; an electron impact ionization source is used, the ion source temperature is 250°C, and the ionization voltage is 70 eV.

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