Detection method and detection system for six olefin compounds in food packaging material
By using solid-phase microextraction and GC-MS detection methods, the chromatographic separation conditions were optimized, the sensitivity and accuracy issues of detecting the migration of olefin compounds in food packaging materials were resolved, and simplified pretreatment and efficient detection were achieved.
Patent Information
- Application Number
- CN202510898144.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-01
- Publication Date
- 2025-09-12
AI Technical Summary
The existing technology lacks effective detection methods to monitor the migration of olefin compounds in food packaging materials. Traditional solvent extraction methods are complex and lack sensitivity, and cannot meet the needs of food safety testing.
Solid phase microextraction fiber head is used to adsorb olefins in the headspace, combined with GC-MS separation and detection. By optimizing chromatographic separation conditions and headspace injection parameters, the pretreatment process is simplified and the detection sensitivity and accuracy are improved.
High-sensitivity detection of six olefin compounds in food packaging materials was achieved, the pretreatment steps were simplified, misidentification of isomers and matrix interference were avoided, and the method is suitable for industrial applications.
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Figure CN120629412A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of food contact material safety detection, in particular to a method for detecting six olefin compounds in food packaging materials. Background Art
[0002] When food packaging materials come into contact with food, toxic and hazardous substances may migrate from the packaging into the food, potentially causing serious harm to the human body. Existing detection methods for migrating substances from food packaging materials focus primarily on plasticizers and antioxidants, but lack effective detection methods for the migration of olefin compounds (particularly unsaturated olefin nitriles). Studies have shown that the migration of these olefin compounds into food can pose potential risks to human health. Therefore, accurately measuring their migration is a key consideration for ensuring food safety. However, traditional solvent extraction methods are complex pretreatment methods, prone to loss of volatile components, and have issues with sensitivity in detecting olefin compounds. Summary of the Invention
[0003] The purpose of the present invention is to propose a method for detecting six olefin compounds in food packaging materials in response to actual needs. The method utilizes the distribution equilibrium of the substance to be tested in the gas phase and liquid phase, adsorbs the olefin substances in the headspace with a solid phase microextraction fiber head, and then separates and detects them by GC-MS. Qualitative analysis is performed based on retention time and characteristic ions, thereby realizing the detection of six olefin compounds in food packaging materials. Compared with traditional solvent extraction methods, the pretreatment process is simpler and the detection sensitivity is higher.
[0004] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions.
[0005] A method for detecting six olefin compounds in food packaging materials, wherein the six olefin compounds are (Z)-9-octadecenenitrile, cis-2-octene, trans-2-octene, 1-octene, 1-hexene, and 1-decene, and the detection method comprises the following steps: Step S1, sample preparation and migration simulation; Cut the food packaging material sample to obtain 1×1 cm sample material fragments, select a food simulant corresponding to the food packaging content, place the sample material fragments in the food simulant and conduct a migration test to obtain a migration test immersion solution; Step S2, headspace sampling pre-treatment; Take an appropriate amount of the migration test immersion solution and transfer it to a 50 mL centrifuge tube. After adding sodium chloride, ultrasonically vibrate for 5 minutes to completely dissolve the sodium chloride to obtain the sample migration test immersion solution. Step S3, standard solution preparation; Weigh six olefin standards separately, prepare 1000 μg / mL single standard stock solutions using chromatographic grade methanol, and store at -20°C in the dark. When used, a series of mixed standard working solutions are prepared using the food simulant selected in step S1 as a matrix, with the concentration range of the mixed standard working solutions being 0.05 μg / mL-50.0 μg / mL; Step S4, drawing a standard curve; Take 5 mL of each of the series of mixed standard working solutions prepared in step S3 and add them to a 20 mL headspace bottle. After adding 8 g of sodium chloride, ultrasonic oscillation is performed for 5 minutes to make the mass concentration of sodium chloride in the migration test immersion solution reach 20% w / v. According to the optimized headspace injection parameters and chromatography-mass spectrometry conditions, the analysis is performed, and the concentration of each substance is used as the horizontal axis and the peak area of the quantitative ion is used as the vertical axis to draw a standard curve; Step S5, sample measurement; 5 mL of the sample migration test immersion solution obtained in step S2 was placed in a 20 mL headspace bottle and sealed. The analysis was performed according to the same headspace injection parameters and chromatography-mass spectrometry conditions as in step S4. The migration amounts of the six olefinic substances in the sample migration test immersion solution were calculated according to the standard curve drawn in step S3.
[0006] Specifically, in step S1, a food simulant corresponding to the contents of the food package is selected by: For water-based foods, 10% ethanol solution is used as a food simulant; for acidic foods, 3% acetic acid solution is used as a food simulant; for oily foods, olive oil or isooctane is used as a food simulant; In the migration test, the corresponding relationship between sample material fragments, temperature conditions and migration time is: Migration simulation of food packaging under short-term use: 70℃, 2h; Migration simulation of food packaging under long-term use: 40°C, 10 days; Migration simulation of food packaging under heating conditions: 60℃, 6h or 100℃, 30min.
[0007] Specifically, the mass concentration of sodium chloride in the sample migration test immersion solution in step S2 is 20% w / v.
[0008] Specifically, the concentrations of the mixed standard working solution in step S3 include 0.05 μg / mL, 0.1 μg / mL, 0.5 μg / mL, 1.0 μg / mL, 5.0 μg / mL, 10.0 μg / mL, 20.0 μg / mL, and 50.0 μg / mL.
[0009] Specifically, the optimized headspace injection parameters and chromatography-mass spectrometry conditions in step S4 are as follows: Headspace injection parameters: headspace equilibrium temperature 80±2°C, equilibrium time 30 min; injection needle temperature 85°C; 100 μm PDMS extraction fiber tip was selected and conditioned at 250°C for 30 min in the gas chromatograph inlet before use; adsorption time 15 min; desorption time 5 min; Chromatographic conditions: The chromatographic column selected was a DB-17MS capillary column with specifications of 30m×0.25mm×0.25μm, and the chromatographic column stationary phase was 50% phenyl-50% methyl polysiloxane; The column oven temperature program was set as follows: initial temperature 40°C, hold for 3 min, increase the temperature to 150°C at 8°C / min, hold for 5 min, then increase the temperature to 280°C at 15°C / min, hold for 10 min; The gas chromatograph GC inlet temperature was 260°C; The carrier gas of the gas chromatograph GC was helium, and the gas flow rate was 1.2 mL / min; The splitless injection mode was initially selected, and the split valve was opened 0.75 min after injection, with the split ratio set to 20:1; Mass spectrometry conditions: The ionization mode was selected as electron bombardment, and the electron energy was set to 70 eV; The ion source temperature was set to 250°C; the transfer line temperature was set to 280°C; The scanning mode is ion monitoring mode, and the quantitative ions and characteristic ions corresponding to the six olefin substances are as follows: (Z)-9-Octadecenonitrile: quantitative ion m / z 96; characteristic ions m / z 81, m / z 67; cis-2-octene: quantitative ion m / z 55; characteristic ions m / z 41, m / z 69; trans-2-octene: quantitative ion m / z 55; characteristic ions m / z 41, m / z 69; 1-Octene: quantitative ion m / z 41; characteristic ions m / z 56, m / z 70; 1-Hexene: quantitative ion m / z 41; characteristic ions m / z 55, m / z 69; 1-Decene: quantification ion m / z 41; characteristic ions m / z 56 and m / z 70.
[0010] Specifically, in step S5, the migration amounts of the six olefinic substances in the sample migration test immersion solution are calculated based on the standard curve drawn in step S3. The calculation formula is as follows: ; In the above formula, is the migration amount, unit is mg / kg; is the measured concentration of the target compound in the sample migration test immersion solution, unit: μg / mL; is the concentration of the target compound in the blank solution, in μg / mL; The volume of the sample migration test immersion solution, unit: mL; is the dilution factor; m is the mass of the food packaging material sample, in g.
[0011] The present invention discloses a detection system adopted by a detection method, comprising a migration test device, a collector, a clamping device, a centrifuge tube and a bracket, wherein the migration test device is fixed to the top of the bracket, a liquid outlet pipe is provided at the bottom of the migration test device, the collector is fixed to the middle of the outer wall of the bracket, the top of the collector is connected to the liquid outlet pipe via a hose, the bottom of the collector is provided with a collection port, the outer wall of the collector is provided with a sodium chloride addition tube, a clamping device for clamping the centrifuge tube is provided below the collector, and the top opening of the centrifuge tube is located below the collection port.
[0012] The migration test device includes a front plate, a rear plate, a containing ring, positioning bolts and butterfly nuts. The front plate and the rear plate are square structures with the same cross-section. Four positioning bolts are fixed to the inner wall of the rear plate. The outer walls of the four positioning bolts can be tangent to the outer wall of the containing ring. The surface of the front plate is provided with four bolt holes for the positioning bolts to pass through. The outer ends of the positioning bolts pass through the bolt holes and are threadedly connected to the butterfly nuts. The inner walls of the front plate, the containing ring and the rear plate can form a containing cavity for accommodating sample material fragments and food simulants. Two liquid inlet pipes are provided on one side of the outer wall of the containing ring, and the liquid outlet pipe is located on the other side of the outer wall of the containing ring.
[0013] The collector has a hollow cylindrical structure, the bottom end of the hose is connected to the top of the inner cavity of the collector, the top end of the hose is connected to the bottom end of the liquid outlet pipe through a quick connection mechanism, and the liquid outlet pipe is provided with a quantitative valve; the quick connection mechanism includes a clamping part and a locking nut, the clamping part is arranged at the bottom end of the liquid outlet pipe, the cross-sectional outer diameter of the clamping part gradually decreases from the end of the liquid outlet pipe to the end close to the accommodating ring, the top end of the hose is externally covered with the locking nut that is clamped with the clamping part, the inner hole of the locking nut forms a taper, and the aperture of the locking nut gradually increases from the top end to the bottom end.
[0014] The clamping device includes a cylinder, a connecting frame, a horizontal slider and a vertical slider. The inner wall of the connecting frame is fixed to the middle part of the outer wall of the bracket. The middle part of the inner wall of the connecting frame is connected to the front end of the cylinder. The piston rod of the cylinder passes through the middle part of the inner wall of the connecting frame and is connected to the middle part of the upper surface of the vertical slider. The vertical slider is an isosceles trapezoidal structure that is wide at the top and narrow at the bottom. Dovetail keys are provided on both side walls of the vertical slider; side holes for the horizontal slider to pass through are provided in the middle part of the side walls of the connecting frame, and a hole for the horizontal slider to pass through is provided in the middle part of the outer wall of the connecting frame. The horizontal slider slides along a horizontal slide groove in the horizontal direction, and the two ends of the horizontal slide groove are connected to the bottom of the side hole. Limit slide grooves are provided on both sides of the inner wall of the horizontal slide groove along its length direction. The front ends of the upper and lower surfaces of the horizontal slider are provided with limit sliders that slide in cooperation with the limit slide groove. The cross-section of the horizontal slider is a right-angled trapezoidal structure, and its inner wall is an inclined surface with the same slope as the vertical slider. A dovetail groove for the sliding of the dovetail key is provided on the inclined surface; a clamping block for clamping the centrifuge tube is fixed to the front end of the horizontal slider.
[0015] The bracket includes a vertical plate, an upper horizontal plate, a lower horizontal plate and an inclined plate, the upper two sides of the inner wall of the vertical plate are respectively connected to the upper horizontal plate, the bottom two sides of the vertical plate are respectively connected to the lower horizontal plate, the upper outer wall of the vertical plate is connected to the top of the inclined plate, and the bottom end of the inclined plate is connected to the rear end top of the two lower horizontal plates; the top outer ends of the two upper horizontal plates are provided with connecting plates, the middle part of the connecting plates is provided with a square hole, the front plate and the rear plate are respectively connected to the top front end and the rear end of the connecting plate; the lower part of the outer wall of the collector is connected to the middle part of the outer wall of the vertical plate by a connecting rod; the rear wall of the connecting frame of the clamping device is connected to the lower part of the outer wall of the vertical plate, and the vertical plate is provided with a cylinder hole for the cylinder to pass through.
[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The method of the present invention achieves baseline separation of cis / trans octene isomers through optimized chromatographic separation conditions (DB-17MS column and programmed temperature), avoiding misidentification of cis / trans isomers. At the same time, it has a good separation effect on the high-boiling point (Z)-9-octadecenenitrile and other olefins, avoiding matrix interference and improving the accuracy of qualitative and quantitative analysis.
[0017] 2. The method of the present invention is easy to operate. Headspace solid-phase microextraction does not require complex solvent extraction and purification steps, which reduces the use of organic solvents, simplifies the pretreatment process, and improves the efficiency of analysis and detection. It can be combined with online thermal desorption-GC / MS and is suitable for industrial detection. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 is a flow chart of the method for detecting six olefin compounds in food packaging materials of the present invention; Figure 2 It is a structural schematic diagram of a detection system used in a detection method of the present invention; Figure 3 It is a left side view of a detection system used in a detection method of the present invention; Figure 4 yes Figure 3 Cross-section at AA; Figure 5 is an enlarged view of the quick connection mechanism of the present invention; Figure 6 yes Figure 3 Cross-section at the middle BB; Figure 7 It is a structural schematic diagram of the migration experimental device of the present invention; Figure 8 It is a schematic structural diagram of the clamping device of the present invention.
[0019] In the figure: 1 migration test device, 2 collector, 3 clamping device, 4 centrifuge tube, 5 bracket, 6 liquid outlet pipe, 7 hose, 8 quick connection mechanism, 9 quantitative valve, 11 front plate, 12 rear plate, 13 accommodating ring, 14 positioning bolt, 15 butterfly nut, 16 bolt hole, 17 liquid inlet pipe, 31 cylinder, 32 connecting frame, 33 horizontal slider, 34 vertical slider, 35 piston rod, 36 dovetail key, 37 side hole, 38 horizontal slide, 39 limit slide, 40 limit slider, 41 dovetail groove, 42 clamping block, 51 vertical plate, 52 upper horizontal plate, 53 lower horizontal plate, 54 inclined plate, 55 connecting plate, 56 square hole, 81 clamping portion, 82 locking nut. DETAILED DESCRIPTION
[0020] In order to facilitate those skilled in the art to understand and implement the present invention, each step of the method proposed in the present invention is described in detail below. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims appended hereto.
[0021] Example like Figure 1 As shown, the present invention discloses a method for detecting six olefin compounds in food packaging materials, wherein the six olefin compounds are (Z)-9-octadecenenitrile, cis-2-octene, trans-2-octene, 1-octene, 1-hexene and 1-decene. The detection method comprises the following steps: Step S1, sample preparation and migration simulation; Cut the food packaging material sample to obtain 1×1 cm sample material fragments, select a food simulant corresponding to the food packaging content, place the sample material fragments in the food simulant and conduct a migration test to obtain a migration test immersion solution; Step S2, headspace sampling pre-treatment; Take an appropriate amount of the migration test immersion solution and transfer it to a 50 mL centrifuge tube. After adding sodium chloride, ultrasonically vibrate for 5 minutes to completely dissolve the sodium chloride to obtain the sample migration test immersion solution. Step S3, standard solution preparation; Weigh six olefin standards separately, prepare 1000 μg / mL single standard stock solutions using chromatographic grade methanol, and store at -20°C in the dark. When used, a series of mixed standard working solutions are prepared using the food simulant selected in step S1 as a matrix, with the concentration range of the mixed standard working solutions being 0.05 μg / mL-50.0 μg / mL; Step S4, drawing a standard curve; Take 5 mL of each of the series of mixed standard working solutions prepared in step S3 and add them to a 20 mL headspace bottle. After adding 8 g of sodium chloride, ultrasonic oscillation is performed for 5 minutes to make the mass concentration of sodium chloride in the migration test immersion solution reach 20% w / v. According to the optimized headspace injection parameters and chromatography-mass spectrometry conditions, the analysis is performed, and the concentration of each substance is used as the horizontal axis and the peak area of the quantitative ion is used as the vertical axis to draw a standard curve; Step S5, sample measurement; 5 mL of the sample migration test immersion solution obtained in step S2 was placed in a 20 mL headspace bottle and sealed. The analysis was performed according to the same headspace injection parameters and chromatography-mass spectrometry conditions as in step S4. The migration amounts of the six olefinic substances in the sample migration test immersion solution were calculated according to the standard curve drawn in step S3.
[0022] Specifically, in step S1, a food simulant corresponding to the contents of the food package is selected by: For water-based foods, 10% ethanol solution is used as a food simulant; for acidic foods, 3% acetic acid solution is used as a food simulant; for oily foods, olive oil or isooctane is used as a food simulant; In the migration test, the corresponding relationship between sample material fragments, temperature conditions and migration time is: Migration simulation of food packaging under short-term use: 70℃, 2h; Migration simulation of food packaging under long-term use: 40°C, 10 days; Migration simulation of food packaging under heated use with packaging: 60℃, 6h or 100℃, 30min.
[0023] Specifically, the mass concentration of sodium chloride in the sample migration test immersion solution in step S2 is 20% w / v.
[0024] In this embodiment, sodium chloride was added to the food simulant to adjust the mass concentration of sodium chloride in the sample migration test immersion solution to 20% w / v. The addition of sodium chloride can reduce the solubility of olefins in water, promote their volatilization into the headspace, significantly improve the extraction efficiency, and thus enhance the detection signal.
[0025] Specifically, the concentrations of the mixed standard working solution in step S3 include 0.05 μg / mL, 0.1 μg / mL, 0.5 μg / mL, 1.0 μg / mL, 5.0 μg / mL, 10.0 μg / mL, 20.0 μg / mL, and 50.0 μg / mL.
[0026] Specifically, the optimized headspace injection parameters and chromatography-mass spectrometry conditions in step S4 are as follows: Headspace injection parameters: headspace equilibrium temperature 80±2°C, equilibrium time 30 min; injection needle temperature 85°C; 100 μm PDMS extraction fiber tip was selected and conditioned at 250°C for 30 min in the gas chromatograph inlet before use; adsorption time 15 min; desorption time 5 min; In this embodiment, based on multiple experimental analyses, the headspace equilibrium temperature was selected to be 80±2°C and the equilibrium time was 30 min. At this temperature and equilibrium time, the distribution coefficients of the six olefinic substances in the headspace reached a good balance, and the response signals of each olefinic substance were stable, which not only ensured sufficient volatility but also reduced interference from high-boiling-point substances, thereby effectively improving detection sensitivity. Chromatographic conditions: The chromatographic column selected was a DB-17MS capillary column with dimensions of 30 m × 0.25 mm × 0.25 μm, and the column stationary phase was 50% phenyl-50% methyl polysiloxane; Comparison of different chromatographic columns revealed that the DB-17MS capillary column exhibits excellent separation selectivity for olefin compounds. Compared to the traditional HP-5MS column, the DB-17MS column offers superior separation of cis / trans isomers (such as the target substances cis-2-octene and trans-2-octene in this example), achieving baseline separation and improving qualitative and quantitative accuracy.
[0027] The column oven temperature program was set as follows: initial temperature 40°C, hold for 3 min, increase the temperature to 150°C at 8°C / min, hold for 5 min, then increase the temperature to 280°C at 15°C / min, hold for 10 min; In this example, by optimizing the column oven heating program, reducing the initial heating rate (from 10°C / min to 8°C / min), and maintaining the temperature at 150°C for a longer time, the separation of low-boiling-point olefins (such as 1-hexene) and high-boiling-point olefins [such as (Z)-9-octadecenenitrile and 1-decene] was significantly improved. In particular, the separation of cis / trans octene isomers was increased from 1.2 in the traditional method to 1.8, thereby better meeting the requirements of quantitative analysis.
[0028] The gas chromatograph GC inlet temperature was 260°C; The carrier gas of the gas chromatograph GC was helium (purity ≥ 99.999%), and the gas flow rate was 1.2 mL / min; In this example, the splitless injection mode was selected. The split valve was opened 0.75 min after injection, and the split ratio was set to 20:1. This can effectively increase the sample injection volume and enhance the detection signal of low-concentration olefins, thereby reducing the detection limit. Mass spectrometry conditions: The ionization mode was selected as electron bombardment, and the electron energy was set to 70 eV; The ion source temperature was set to 250°C, and the transfer line temperature was set to 280°C. This can improve ionization efficiency and ensure that there is no condensation during the sample transfer from GC to MS. This can especially enhance the response intensity of the characteristic ion of the high-boiling-point (Z)-9-octadecenenitrile, thereby ensuring detection stability. The scanning mode is ion monitoring mode, and the quantitative ions and characteristic ions corresponding to the six olefin substances are as follows: (Z)-9-Octadecenonitrile: quantitative ion m / z 96; characteristic ions m / z 81, m / z 67; cis-2-octene: quantitative ion m / z 55; characteristic ions m / z 41, m / z 69; trans-2-octene: quantitative ion m / z 55; characteristic ions m / z 41, m / z 69; 1-Octene: quantitative ion m / z 41; characteristic ions m / z 56, m / z 70; 1-Hexene: quantitative ion m / z 41; characteristic ions m / z 55, m / z 69; 1-Decene: quantification ion m / z 41; characteristic ions m / z 56 and m / z 70.
[0029] Specifically, in step S5, the migration amounts of the six olefinic substances in the sample migration test immersion solution are calculated based on the standard curve drawn in step S3. The calculation formula is as follows: ; In the above formula, is the migration amount, unit is mg / kg; is the measured concentration of the target compound in the sample migration test immersion solution, unit: μg / mL; is the concentration of the target compound in the blank solution, in μg / mL; The volume of the sample migration test immersion solution, unit: mL; is the dilution factor; m is the mass of the food packaging material sample, in g.
[0030] The following is an experiment on detecting six olefin compounds in food packaging materials using the method of the present invention to further illustrate the technical effect of the method of the present invention.
[0031] The experimental configuration is as follows: 1. Experimental instruments; Gas chromatography-mass spectrometry (equipped with electron impact source EI, 70eV); Headspace solid phase microextraction device (with 100 μm polydimethylsiloxane PDMS extraction fiber head); Headspace injection vials (20 mL, with sealing ferrules and aluminum caps); Constant temperature water bath oscillator; Analytical balance (precision 0.1 mg); Microinjector (10μL, 100μL); Ultrasonic cleaner.
[0032] 2. Experimental reagents; Basic reagents: methanol (chromatographic grade); sodium chloride (analytical grade), calcined at 400°C for 4 h; deionized water (18.2 MΩ cm); Food simulants (migration medium): 10% ethanol solution (v / v), 3% acetic acid solution (w / v), olive oil, isooctane; Six olefin standards: (Z)-9-octadecenenitrile (purity ≥99.0%), cis-2-octene (purity ≥98.5%), trans-2-octene (purity ≥98.5%), 1-octene (purity ≥99.0%), 1-hexene (purity ≥99.0%), and 1-decene (purity ≥99.0%).
[0033] 3. Experimental process and results; (1) Linear range The six olefins showed good linearity in the concentration range of 0.05 μg / mL-50.0 μg / mL, with correlation coefficients R²≥0.999.
[0034] (2) Detection limit and quantification limit The limit of detection (LOD) was determined at a signal-to-noise ratio of 3 (S / N=3), and the limit of quantification (LOQ) was determined at a signal-to-noise ratio of 10 (S / N=10). The optimized method significantly reduced the limit of detection (LOD) to ≤0.005 mg / kg for 1-hexene, ≤0.01 mg / kg for (Z)-9-octadecenenitrile, and ≤0.008 mg / kg for the remaining olefins. The limit of quantification (LOQ) ranged from ≤0.02 mg / kg to 0.05 mg / kg, meeting the requirements for detecting trace olefin migration in food packaging materials.
[0035] (3) Precision Six replicate measurements were performed on spiked samples at three concentration levels: low (0.1 mg / kg), medium (1.0 mg / kg), and high (10.0 mg / kg). The relative standard deviations (RSDs) were all ≤8%, with the RSDs for cis / trans octene isomers ≤5%, indicating good precision of the method.
[0036] (4) Accuracy Low, medium and high concentration standards were added to blank samples, and the spiked recoveries were 85%-115%, of which the recovery rates of (Z)-9-octadecenenitrile were 88%-112% and 1-hexene were 85%-110%, meeting the requirements for quantitative analysis.
[0037] In summary, the method of the present invention significantly improves the detection sensitivity by optimizing the headspace injection parameters (such as salt effect, equilibrium temperature and time) and adopting the headspace solid-phase microextraction HS-SPME technology. The detection limit is as low as μg / kg, which is 30-50% lower than the traditional solvent extraction method and can be applied to the detection of trace olefin migration. The baseline separation of cis / trans octene isomers is achieved by optimizing the chromatographic separation conditions (DB-17MS column and programmed temperature), avoiding the misidentification of cis / trans isomers, and the separation effect of high-boiling point (Z)-9-octadecenenitrile and other olefins is good, avoiding matrix interference, and effectively improving the detection accuracy.
[0038] like Figure 2-Figure 4As shown, the present invention discloses a detection system used in a detection method, comprising a migration test device 1, a collector 2, a clamping device 3, a centrifuge tube 4 and a bracket 5, wherein the migration test device 1 is fixed to the top of the bracket 5, a liquid outlet pipe 6 is provided at the bottom of the migration test device 1, the collector 2 is fixed to the middle of the outer wall of the bracket 5, the top of the collector 2 is connected to the liquid outlet pipe 6 through a hose 7, a collection port 21 is provided at the bottom of the collector 2, a sodium chloride addition tube 22 is provided on the outer wall of the collector 2, and a tube 23 for clamping the centrifuge tube is provided below the collector 2. 4, the top opening of the centrifuge tube 4 is located below the collecting port 21, the food packaging material sample fragments and the food simulant are placed in the migration test device 1 and subjected to a migration test according to temperature conditions and migration time, and then the liquid is input into the collector 2 through the outlet pipe 6 at the bottom of the migration test device 1 through the hose 7, the centrifuge tube 4 is clamped below the collector 2 through the clamping device 3, the migration test immersion solution is collected, sodium chloride is added through the sodium chloride addition tube 22, and the centrifuge tube is ultrasonically oscillated for 5 minutes to completely dissolve the sodium chloride to obtain the sample migration test immersion solution.
[0039] Further, such as Figure 7 As shown, the migration test device 1 includes a front plate 11, a rear plate 12, a receiving ring 13, a positioning bolt 14 and a butterfly nut 15. The front plate 11 and the rear plate 12 are square structures with the same cross-section. Four positioning bolts 14 are fixed to the inner wall of the rear plate 12. The outer walls of the four positioning bolts 14 can be tangent to the outer wall of the receiving ring 13. The surface of the front plate 11 is provided with four bolt holes 16 for the positioning bolts 14 to pass through. The outer ends of the positioning bolts 14 pass through the bolt holes 16 and are connected to the butterfly nuts 15 by threads. The inner walls of the front plate 11, the receiving ring 13 and the rear plate 12 can form a receiving cavity for accommodating sample material fragments and food simulants. The outer wall of the receiving ring 13 is Two liquid inlet pipes 17 are provided on the side, and the liquid outlet pipe 6 is located on the other side of the outer wall of the accommodating ring 13. When it is necessary to prepare the migration test immersion solution, the butterfly nut 15 is opened to remove the front plate 11, and the food packaging sample fragments are placed in the accommodating ring 13, and then the front plate 11 is covered, and the front plate 11 and the rear plate 12 are clamped to the accommodating ring 13 through the butterfly nut 15. Then, the food simulant is injected through the liquid inlet pipe 17, and the migration test is carried out according to the temperature conditions and migration time. Another way to prepare the migration test immersion solution is to cut the food packaging sample into a circle slightly larger than the outer diameter of the accommodating ring 13, clamp two food packaging samples between the accommodating ring 13 and the front plate 11 and the rear plate 12 respectively, and then inject the food simulant.
[0040] Furthermore, the collector 2 is a hollow cylindrical structure, and the bottom end of the hose 7 is connected to the top of the inner cavity of the collector 2, as shown in FIG. Figure 5As shown, the top end of the hose 7 is connected to the bottom end of the liquid outlet pipe 6 through a quick connection mechanism 8. The liquid outlet pipe 6 is provided with a quantitative valve 9. By setting the quantitative valve 9, a suitable migration test immersion solution can be injected according to the size of the centrifuge tube 4; the quick connection mechanism 8 includes a clamping portion 81 and a locking nut 82. The clamping portion 81 is provided at the bottom end of the liquid outlet pipe 6. The cross-sectional outer diameter of the clamping portion 81 gradually decreases from the end of the liquid outlet pipe 6 to the end close to the accommodating ring 13. The top end of the hose 7 is externally sleeved with the locking nut 82 that is clamped with the clamping portion 81. The inner hole of the locking nut 82 forms a taper. The aperture of the locking nut 82 gradually increases from the top end to the bottom end. The locking nut 62 has a taper opposite to that of the clamping portion, so that the locking nut 62 can better cooperate with the clamping portion 61 to lock the grouting pipe 5. Since the food packaging material sample fragments need to be disassembled when placed in the migration test device 1, the hose 7 and the liquid outlet pipe 6 need to be separated. Therefore, the hose 7 and the liquid outlet pipe 6 are connected by a quick connection mechanism 8 to facilitate quick connection and disassembly of the two.
[0041] Further, such as Figure 6 and Figure 8The cam 33 is fixed to the upper and lower parts of the support frame 32, and the cam 33 is fixed to the upper and lower parts of the support frame 32. The cam 33 is fixed to the upper and lower parts of the support frame 32, and the cam 33 is fixed to the upper and lower parts of the support frame 32. The cam 33 is fixed to the upper and lower parts of the support frame 32, and the cam 33 is fixed to the upper and lower parts of the support frame 32. The cam 33 is fixed to the upper and lower parts of the support frame 32, and the cam 33 is fixed to the upper and lower parts of the support frame 32. The front end is provided with a limit slider 40 that slides in cooperation with the limit slide groove 39. The cross-section of the horizontal slider 33 is a right-angled trapezoidal structure, and its inner wall is an inclined surface with the same slope as the vertical slider 34, and the inclined surface is provided with a dovetail groove 41 for the sliding of the dovetail key 36; the front end of the horizontal slider 33 is fixed with a clamping block 42 for clamping the centrifuge tube 4. By arranging a dovetail key 36 on the side wall of the vertical slider 34 and arranging a dovetail groove 41 on the inclined surface of the vertical slider 34, the vertical slider 34 is driven by the cylinder 31 to move along its axial direction. The power can be converted into power for the horizontal slider 33 to slide along the side hole 37. By arranging limit slide grooves 39 on both sides of the inner wall of the horizontal slide groove 38 along its length direction, the limit slider 40 that slides in cooperation with the limit slide groove 39 is provided below the front and rear walls of the horizontal slider 33, it can be ensured that the horizontal slider 33 can slide stably in the horizontal direction.
[0042] The working process of the clamping device 3: when the clamping blocks 42 on both sides need to be opened, the piston rod 55 of the cylinder 31 is in an extended state, and the vertical slider 34 slides to the front of the inner walls of the horizontal sliders 33 on both sides; when the piston rod 35 of the cylinder 31 retracts upward, the vertical slider 34 can drive the horizontal sliders 33 on both sides to move inward, thereby driving the two clamping blocks 42 to move inward to clamp the centrifuge tube 4.
[0043] Furthermore, the bracket 5 includes a vertical plate 51, an upper horizontal plate 52, a lower horizontal plate 53 and an inclined plate 54, the upper two sides of the inner wall of the vertical plate 51 are respectively connected to the upper horizontal plate 52, the bottom two sides of the vertical plate 51 are respectively connected to the lower horizontal plate 53, the upper outer wall of the vertical plate 51 is connected to the top of the inclined plate 54, and the bottom end of the inclined plate 54 is connected to the rear end top of the two lower horizontal plates 53; the top outer ends of the two upper horizontal plates 52 are provided with a connecting plate 55, the middle part of the connecting plate 55 is provided with a square hole 56, the front plate 11 and the rear plate 12 are respectively connected to the top front end and rear end of the connecting plate 55; the lower part of the outer wall of the collector 2 is connected to the middle part of the outer wall of the vertical plate 51 by a connecting rod; the rear wall of the connecting frame 32 of the clamping device 3 is connected to the lower outer wall of the vertical plate 51, and the vertical plate 51 is provided with a cylinder hole for the cylinder 31 to pass through.
[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.
Claims
1. A method for detecting six olefin compounds in food packaging materials, wherein the six olefin compounds are (Z)-9-octadecenenitrile, cis-2-octene, trans-2-octene, 1-octene, 1-hexene and 1-decene, characterized in that: The detection method includes the following steps: Step S1, sample preparation and migration simulation; Select food simulants corresponding to the contents of food packaging, conduct migration tests on food packaging materials by bag making, full immersion, filling or migration tank, and obtain migration test immersion solutions; Step S2, headspace sampling pre-treatment; Take an appropriate amount of the migration test immersion solution and transfer it to a 50 mL centrifuge tube. After adding sodium chloride, ultrasonically vibrate for 5 minutes to completely dissolve the sodium chloride to obtain the sample migration test immersion solution. Step S3, standard solution preparation; Weigh six olefin standards separately, prepare 1000 μg / mL single standard stock solutions using chromatographic grade methanol, and store at -20°C in the dark. When used, a series of mixed standard working solutions are prepared using the food simulant selected in step S1 as a matrix, with the concentration range of the mixed standard working solutions being 0.05 μg / mL-50.0 μg / mL; Step S4, drawing a standard curve; Take 5 mL of each of the series of mixed standard working solutions prepared in step S3 and add them to a 20 mL headspace bottle. After adding 8 g of sodium chloride, ultrasonic oscillation is performed for 5 minutes to make the mass concentration of sodium chloride in the migration test immersion solution reach 20% w / v. According to the optimized headspace injection parameters and chromatography-mass spectrometry conditions, analyze the solution and draw a standard curve with the concentration of each substance as the horizontal axis and the peak area of the quantitative ion as the vertical axis. Step S5, sample measurement; 5 mL of the sample migration test immersion solution obtained in step S2 was placed in a 20 mL headspace bottle and sealed. The analysis was performed according to the same headspace injection parameters and chromatography-mass spectrometry conditions as in step S4. The migration amounts of the six olefinic substances in the sample migration test immersion solution were calculated according to the standard curve drawn in step S4.
2. The method for detecting six olefin compounds in food packaging materials according to claim 1, characterized in that: In step S1, a food simulant corresponding to the contents of the food package is selected, and the method for selecting the food simulant is as follows: For water-based foods, 10% ethanol solution is used as a food simulant; for acidic foods, 3% acetic acid solution is used as a food simulant; for oily foods, olive oil or isooctane is used as a food simulant; In the migration test, the corresponding relationship between sample material fragments, temperature conditions and migration time is: Migration simulation of food packaging under short-term use: 70℃, 2h; Migration simulation of food packaging under long-term use: 40°C, 10 days; Migration simulation of food packaging under heating conditions: 60℃, 6h or 100℃, 30min.
3. The method for detecting six olefin compounds in food packaging materials according to claim 1, characterized in that: The mass concentration of sodium chloride in the sample migration test immersion solution in step S2 is 20% w / v.
4. The method for detecting six olefin compounds in food packaging materials according to claim 1, characterized in that: The concentrations of the mixed standard working solution in step S3 include 0.05 μg / mL, 0.1 μg / mL, 0.5 μg / mL, 1.0 μg / mL, 5.0 μg / mL, 10.0 μg / mL, 20.0 μg / mL, and 50.0 μg / mL.
5. The method for detecting six olefin compounds in food packaging materials according to claim 1, characterized in that: The optimized headspace injection parameters and chromatography-mass spectrometry conditions in step S4 are as follows: Headspace injection parameters: headspace equilibrium temperature 80±2°C, equilibrium time 30 min; injection needle temperature 85°C; 100 μm PDMS extraction fiber tip was selected and conditioned at 250°C for 30 min in the gas chromatograph GC injection port before use; adsorption time 15 min; desorption time 5 min; Chromatographic conditions: The chromatographic column selected was a DB-17MS capillary column with specifications of 30m×0.25mm×0.25μm, and the chromatographic column stationary phase was 50% phenyl-50% methyl polysiloxane; The column oven temperature program was set as follows: initial temperature 40°C, hold for 3 min, increase the temperature to 150°C at 8°C / min, hold for 5 min, then increase the temperature to 280°C at 15°C / min, hold for 10 min; The gas chromatograph GC inlet temperature was 260°C; The carrier gas of the gas chromatograph GC was helium, and the gas flow rate was 1.2 mL / min; The splitless injection mode was initially selected, and the split valve was opened 0.75 min after injection, with the split ratio set to 20:1; Mass spectrometry conditions: The ionization mode was selected as electron bombardment, and the electron energy was set to 70 eV; The ion source temperature was set to 250°C; the transfer line temperature was set to 280°C; The scanning mode is ion monitoring mode, and the quantitative ions and characteristic ions corresponding to the six olefin substances are as follows: (Z)-9-Octadecenonitrile: quantitative ion m / z 96; characteristic ions m / z 81, m / z 67; cis-2-octene: quantitative ion m / z 55; characteristic ions m / z 41, m / z 69; trans-2-octene: quantitative ion m / z 55; characteristic ions m / z 41, m / z 69; 1-Octene: quantitative ion m / z 41; characteristic ions m / z 56, m / z 70; 1-Hexene: quantitative ion m / z 41; characteristic ions m / z 55, m / z 69; 1-Decene: quantification ion m / z 41; characteristic ions m / z 56 and m / z 70.
6. The method for detecting six olefin compounds in food packaging materials according to claim 1, characterized in that: In step S5, the migration amounts of the six olefinic substances in the sample migration test immersion solution are calculated based on the standard curve drawn in step S3. The calculation formula is as follows: ； In the above formula, is the migration amount, unit is mg / kg; is the measured concentration of the target compound in the sample migration test immersion solution, unit: μg / mL; is the concentration of the target compound in the blank solution, in μg / mL; The volume of the sample migration test immersion solution, unit: mL; is the dilution factor; m is the mass of the food packaging material sample, in g.
7. A detection system used in the detection method according to claim 1, characterized in that: The invention comprises a migration test device (1), a collector (2), a clamping device (3), a centrifuge tube (4) and a bracket (5), wherein the migration test device (1) is fixed to the top of the bracket (5), a liquid outlet pipe (6) is provided at the bottom of the migration test device (1), the collector (2) is fixed to the middle of the outer wall of the bracket (5), the top of the collector (2) is connected to the liquid outlet pipe (6) via a hose (7), the bottom of the collector (2) is provided with a collecting port (21), the outer wall of the collector (2) is provided with a sodium chloride addition pipe (22), a clamping device (3) for clamping the centrifuge tube (4) is provided below the collector (2), and the top opening of the centrifuge tube (4) is located below the collecting port (21); The migration test device (1) comprises a front plate (11), a rear plate (12), a receiving ring (13), a positioning bolt (14) and a butterfly nut (15). The front plate (11) and the rear plate (12) are square structures with the same cross-section. Four positioning bolts (14) are fixed to the inner wall of the rear plate (12). The outer walls of the four positioning bolts (14) can be tangent to the outer wall of the receiving ring (13). The surface of the front plate (11) is provided with four positioning bolts (14). The bolt (14) passes through the bolt hole (16), and the outer end of the positioning bolt (14) passes through the bolt hole (16) and is connected to the butterfly nut (15) by a thread. The inner wall of the front plate (11), the accommodating ring (13) and the rear plate (12) can form an accommodating cavity for accommodating sample material fragments and food simulants. Two liquid inlet pipes (17) are provided on one side of the outer wall of the accommodating ring (13), and the liquid outlet pipe (6) is located on the other side of the outer wall of the accommodating ring (13).
8. The detection system used in the detection method according to claim 7, characterized in that: The collector (2) is in a hollow cylindrical structure. The bottom end of the hose (7) is in communication with the top of the inner cavity of the collector (2). The top end of the hose (7) is connected to the bottom end of the liquid outlet pipe (6) through a quick connection mechanism (8). The liquid outlet pipe (6) is provided with a quantitative valve (9). The quick connection mechanism (8) includes a clamping portion (81) and a locking nut (82). The clamping portion (81) is provided at the bottom end of the liquid outlet pipe (6). The cross-sectional outer diameter of the clamping portion (81) gradually decreases from the end of the liquid outlet pipe (6) to the end close to the accommodating ring (13). The top end of the hose (7) is provided with the locking nut (82) that is clamped with the clamping portion (81). The inner hole of the locking nut (82) forms a taper. The aperture of the locking nut (82) gradually increases from the top end to the bottom end.
9. The detection system used in the detection method according to claim 8, characterized in that: The clamping device (3) includes a cylinder (31), a connecting frame (32), a horizontal slider (33) and a vertical slider (34), the inner wall of the connecting frame (32) is fixed to the middle of the outer wall of the bracket (5), the middle of the inner wall of the connecting frame (32) is connected to the front end of the cylinder (31), the piston rod (35) of the cylinder (31) passes through the middle of the inner wall of the connecting frame (32) and is connected to the middle of the upper surface of the vertical slider (34), the vertical slider (34) is an isosceles trapezoidal structure with a width at the top and a narrowness at the bottom, and dovetail keys (36) are provided on both side walls of the vertical slider (34); side holes (37) for the horizontal slider (33) to pass through are provided in the middle of the two side walls of the connecting frame (32), and the outer wall of the connecting frame (32) is provided with a plurality of holes (37) for the horizontal slider (33) to pass through. A horizontal slide groove (38) is provided in the middle for the horizontal slider (33) to slide in the horizontal direction, and the two ends of the horizontal slide groove (38) are connected to the bottom of the side hole (37). The inner wall of the horizontal slide groove (38) is provided with a limit slide groove (39) along its length direction. The front ends of the upper and lower surfaces of the horizontal slider (33) are provided with a limit slider (40) that slides in cooperation with the limit slide groove (39). The cross section of the horizontal slider (33) is a right-angled trapezoidal structure, and its inner wall is an inclined surface with the same slope as that of the vertical slider (34). A dovetail groove (41) for the dovetail key (36) to slide is provided on the inclined surface; the front end of the horizontal slider (33) is fixed with a clamping block (42) for clamping the centrifuge tube (4).
10. The detection system used in the detection method according to claim 9, characterized in that: The bracket (5) comprises a vertical plate (51), an upper horizontal plate (52), a lower horizontal plate (53) and an inclined plate (54), wherein the upper sides of the inner wall of the vertical plate (51) are respectively connected to the upper horizontal plates (52), and the lower sides of the bottom of the vertical plate (51) are respectively connected to the lower horizontal plates (53), the upper side of the outer wall of the vertical plate (51) is connected to the top of the inclined plate (54), and the bottom end of the inclined plate (54) is connected to the top of the rear ends of the two lower horizontal plates (53); the tops of the two upper horizontal plates (52) are connected to the upper ends of the lower horizontal plates (53); A connecting plate (55) is provided at the outer end, a square hole (56) is provided in the middle of the connecting plate (55), and the front plate (11) and the rear plate (12) are respectively connected to the top front end and the rear end of the connecting plate (55); the lower part of the outer wall of the collector (2) is connected to the middle part of the outer wall of the vertical plate (51) through a connecting rod; the rear wall of the connecting frame (32) of the clamping device (3) is connected to the lower part of the outer wall of the vertical plate (51), and the vertical plate (51) is provided with a cylinder hole for the cylinder (31) to pass through.