Non-targeted screening detection method for migration volume of non-volatile substances in bamboo fiber plastic

Abstract

The invention belongs to the technical field of food safety detection, and particularly relates to a non-targeted screening detection method for the migration quantity of non-volatile substances in bamboo fiber plastic. According to the method, a high performance liquid chromatography (HPLC) technology is applied, and a quadrupole-time-of-flight high-resolution mass spectrometer (QTOF) is combined, so that the migration volume of the non-volatile substances in the bamboo fiber plastic product migration liquid can be quickly screened; according to the method disclosed by the invention, the detection limit of screening is 0.01 mg / kg under the condition that S / V in a migration test is consistent with S / V in an actual situation; the method is a screening method, has the characteristics of simplicity and convenience in operation, high stability, good reproducibility and the like, aims at screening potential risk substances as much as possible, can comprehensively evaluate the migration quantity of non-volatile substances in the bamboo fiber plastic product, and ensures the safety of the bamboo fiber plastic product.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food safety detection, and particularly relates to a non-target screening detection method for the migration amount of non-volatile substances in bamboo fiber plastic. BACKGROUND

[0002] Plastics are widely used in food contact materials due to their light weight, durability and cost-effectiveness. In order to reduce plastic white pollution and reduce dependence on petroleum, bamboo fiber, as a high-quality raw material in China, has the advantages of strong environmental protection, multiple functions, strong safety, etc., and has become a major alternative source of plastics in the field of food contact materials. In recent years, with the awakening of consumers' environmental awareness and the upgrading of health needs, the selection criteria for food contact materials and products have shifted from single functionality to a multi-dimensional value system. The "four-dimensional decision model" composed of aesthetic appearance, practicality, durability and price sensitivity is reshaping the industry's product development logic. Against this background, bamboo fiber and plastic composite materials, with their unique ecological advantages and performance balance, have become the focus of market innovation.

[0003] At present, bamboo fiber plastic products on the market mainly use bamboo powder as raw material, often mixed with corn starch, wheat fiber and other plant components, and also add melamine resin, polylactic acid resin or polypropylene resin and other plastic resin components. Its production and processing process involves high temperature, mixing, stamping, demolding and other processes. In addition, in order to promote the effective combination of bamboo fiber and plastic matrix, surfactants, compatibilizers and other additive ingredients may be added during processing. Due to the uncertainty of raw materials and input ingredients, combined with the complexity of the production process, the safety of bamboo fiber plastic products faces many unknown factors, and how to effectively protect the food safety of consumers has become a major problem to be solved.

[0004] Therefore, how to overcome the defect that the non-volatile substances in the composite material mixed with multiple component plant fibers and plastic components are not easy to detect is a technical problem that needs to be solved in the field.

[0005] It should be noted that the above information disclosed in this background section is only used to understand the background of the present application, and therefore, the above description is not considered to constitute prior art information. SUMMARY

[0006] The embodiments of the present disclosure at least provide a non-target screening detection method for the migration amount of non-volatile substances in bamboo fiber plastic.

[0007] In a first aspect, the embodiments of the present disclosure provide a non-targeted screening detection method for non-volatile substance migration amount in bamboo fiber plastic, comprising: preparing food simulant, internal standard stock solution A and internal standard working solution B; migration test: using organic solvent to rinse the vessels involved in the migration test, and then performing the migration test to obtain soaking liquid, recording the volume V1 of the food simulant, the area S1 of the sample contacting with the food simulant in the migration experiment, recording the area S2 of the sample actually used and contacting with the food, and the volume or mass V2 of the sample actually used and contacting with the food according to the actual use condition of the sample to be tested; pretreating the soaking liquid; blank test: selecting food simulant not contacting with the sample to repeat the foregoing migration experiment, and repeating the pretreatment of the foregoing soaking liquid to obtain blank test solution A; determination: determining the blank test solution A and the soaking liquid by high performance liquid chromatography-quadrupole-time-of-flight high resolution mass spectrometry to obtain total ion chromatogram, primary high resolution mass spectrum and corresponding secondary high resolution mass spectrum, wherein, each batch of test solution is collected once in positive ion mode and negative ion mode respectively; data processing: when the extracted ion chromatogram peak area of the unknown substance in the sample total ion chromatogram meets the two conditions of being more than 10 times of the peak area of the blank sample and being more than 1 times of the peak area of the internal standard with similar structure, the next step of analysis is performed; calculating the migration amount X1 of the detected substance:

[0008]

[0009] In the formula:

[0010] A 目标 is the peak area of the target substance screened out in the soaking liquid of the sample to be tested in the chromatogram;

[0011] A 内标 is the peak area of the target substance corresponding to the internal standard in the soaking liquid of the sample to be tested in the chromatogram;

[0012] A 0目标 is the peak area of the target substance screened out in the soaking liquid of the blank sample in the chromatogram;

[0013] A 0内标 is the peak area of the target substance corresponding to the internal standard in the soaking liquid of the blank sample in the chromatogram;

[0014] C 内标 is the concentration of the internal standard in the soaking liquid of the sample to be tested, in milligrams per liter (mg / L);

[0015] V1 is the volume of the food simulant in the migration experiment;

[0016] S1 is the area of the sample contacting with the food simulant in the migration experiment;

[0017] V2 is the volume or mass of the sample actually used and contacting with the food;

[0018] S2 is the area of the sample actually in contact with the food during use.

[0019] In an alternative embodiment, the preparation method of the food simulant comprises: preparing acetic acid and water at a volume ratio of 1:24 to obtain a 4% acetic acid solution; preparing ethanol and water at a volume ratio of 1:9, 1:4, 1:1, 19:1 to obtain a 10%, 20%, 50%, 95% ethanol solution.

[0020] In an alternative embodiment, the preparation of the internal standard stock solution A comprises: weighing the internal standard substance and acetone in proportion, dissolving in a beaker and then transferring to a volumetric flask to configure the internal standard stock solution A, and storing at a temperature of-20℃ in the dark; the preparation of the internal standard working solution B comprises: diluting the internal standard stock solution A with methanol to configure the internal standard working solution B, and storing at a temperature of-20℃ in the dark.

[0021] In an alternative embodiment, in the pretreatment of the soaking solution, for the soaking solution containing isooctane, 1.00 mL of the soaking solution is accurately transferred to a sample vial, blown to 0.50 mL with mild nitrogen, 0.50 mL of isopropyl alcohol and a certain volume of internal standard working solution B are added, mixed and then detected and analyzed on the machine; for the soaking solution not containing isooctane, 1.00 mL of the soaking solution is accurately transferred to a sample vial, a certain volume of internal standard working solution B is added, mixed and then the soaking solution is obtained and detected and analyzed on the machine.

[0022] In an alternative embodiment, the volume of the internal standard working solution B added in the pretreatment of the soaking solution is 10 μL-100 μL.

[0023] In an alternative embodiment, the chromatographic column used in the high performance liquid chromatography-quadrupole-time-of-flight high resolution mass spectrometry method is a Waters T3 column or an equivalent column, and the mobile phase used in chromatographic separation is 5 mmol / L ammonium formate and different concentrations of methanol, the flow rate is 0.3 mL / min, the column temperature is 40℃, and the gradient elution comprises: 0-8 min, the concentration of methanol is 10%; 8-17 min, the concentration of methanol is 100%; 17-20 min, the concentration of methanol is 10%.

[0024] In an alternative embodiment, the high performance liquid chromatography-quadrupole-time-of-flight high resolution mass spectrometry detector is a quadrupole-time-of-flight high resolution mass spectrometer, and the mass spectrometry conditions are as follows: positive ion mode: ion source gas path 1: 55 PSI; curtain gas: 30 PSI; CAD gas: 7; temperature: 550 DEG C; TOF MASS scan range: 100-1500 Da; acquisition mode: IDA; nozzle voltage: 5500 V; de-clustering voltage: 60 V; collision energy: 10 V; secondary mass spectrum scan range: 30-1500 Da; de-clustering voltage: 60 V; collision energy: 35 V; adjustment range: 15 V; negative ion mode: ion source gas path 1: 55 PSI; curtain gas: 30 PSI; CAD gas: 7; temperature: 550 DEG C; TOF MASS scan range: 100-1500 Da; acquisition mode: IDA; nozzle voltage: -4500 V; de-clustering voltage: 60 V; collision energy: 10 V; secondary mass spectrum scan range: 30-1500 Da; de-clustering voltage: 60 V; collision energy: 35 V; adjustment range: 15 V.

[0025] In an alternative embodiment, the data processing includes: performing spectral library retrieval on the primary high resolution mass spectrum and the corresponding secondary high resolution mass spectrum by using a Library database, and if the spectral library matching degree is greater than or equal to 70%, confirming the substance structure in combination with the molecular structure and material information; if the spectral library matching degree is less than 70%, finding the primary high resolution mass spectrum and the secondary high resolution mass spectrum of the unknown substance in the OS Explorer, and performing spectral library retrieval on the primary high resolution mass spectrum and the secondary high resolution mass spectrum by using the Library database, and if the spectral library matching degree is greater than or equal to 70%, confirming the substance structure in combination with the molecular structure and material information; if the spectral library matching degree is less than 70%, performing Formular Finder function, calculating possible molecular formula in combination with the primary mass spectrum accurate mass number and isotopic division ratio, and verifying according to certain mass spectrum cracking rules and the secondary mass spectrum accurate mass number; combining the material information, common additives and product upstream and downstream processes to draw possible structures of the compound and verifying by using the Fragment Pane function; and performing qualitative confirmation by using a standard substance to configure a standard solution, and confirming the retention time and the mass spectrum.

[0026] The Formular Finder function, in combination with the primary mass spectrum accurate mass number and isotopic division ratio, calculates possible molecular formula, and verifies according to certain mass spectrum cracking rules and the secondary mass spectrum accurate mass number; combining the material information, common additives and product upstream and downstream processes to draw possible structures of the compound and verifying by using the Fragment Pane function; and performing qualitative confirmation by using a standard substance to configure a standard solution, and confirming the retention time and the mass spectrum.

[0027] The method has the advantages that the non-target screening and detection method for the migration amount of non-volatile substances in the bamboo fiber plastic can quickly screen the migration amount of non-volatile substances in the migration liquid of the bamboo fiber plastic product by using the high performance liquid chromatography (HPLC) in combination with the quadrupole-time-of-flight high resolution mass spectrometer (QTOF); the detection limit of the method is 0.01 mg / kg under the condition that the S / V in the migration test is consistent with the actual situation; the method is a screening method, and has the characteristics of simple operation, high stability and good reproducibility, and is intended to screen as many potential risk substances as possible, so that the migration amount of non-volatile substances in the bamboo fiber plastic product can be comprehensively evaluated, and the safety of the bamboo fiber plastic product is ensured.

[0028] Other features and advantages of the present application will be set forth in the descriptions that follow, and in part will be apparent from the description, or can be learned by practice of the application. The purposes and other advantages of the present application will be realized and attained by the structures particularly pointed out in the description and the appended drawings.

[0029] In order to make the above objectives, features and advantages of the present application more apparent, the following will specifically describe a preferred embodiment, and combine with the accompanying drawings, make a detailed description as follows. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0031] Figure 1 DNOP-D4 standard extraction chromatogram (m / z: 395.3094 ([M+H]+)) provided by the embodiment of the present disclosure;

[0032] Figure 2 4-nitrophenol tetrabutylammonium standard extraction chromatogram (m / z: 242.2842 ([M+H]+)) provided by the embodiment of the present disclosure;

[0033] Figure 3 Peanut acid-D39 standard extraction chromatogram (m / z: 350.5404 ([M-H]-)) provided by the embodiment of the present disclosure;

[0034] Figure 4 4'-bromobiphenylol standard extraction chromatogram (m / z: 246.9764 ([M-H]-)) provided by the embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the present application will be described clearly and completely in the following with reference to the drawings. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0036] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0037] In this document, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0038] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0039] Non-targeted screening technology can be used for high-throughput screening and accurate detection of natural active ingredients and contaminants derived from plant fibers, residual monomers and oligomers and degradation products from plastics, and additives such as process aids and bactericides from different processing techniques. Through migration simulation experiments, the migration of hazardous substances in bamboo fiber plastic products can be analyzed, key factors influencing migration can be identified, and migration mechanisms and patterns can be revealed, further ensuring the safety of food contact materials and products.

[0040] Currently, there is no non-targeted screening method for the migration of non-volatile substances in bamboo fiber plastic products. In order to fill the gap in detection methods and ensure the safety of food contact materials and products, it is necessary to propose a simple, efficient and accurate method to provide an effective screening means for non-volatile substances in bamboo fiber plastic products.

[0041] The shortcomings of the above solutions are the result of the inventor's practical experience and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure below should be considered as the inventor's contribution to this disclosure.

[0042] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0043] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0044] This disclosure provides a non-targeted screening method for detecting the migration of non-volatile substances in bamboo fiber plastics, including: preparing a food simulant, an internal standard stock solution A, and an internal standard working solution B; a migration test: rinsing the vessels involved in the migration test with an organic solvent, followed by the migration test to obtain an immersion solution; recording the volume V1 of the food simulant and the area S1 of the sample in contact with the food simulant during the migration test; recording the area S2 of the sample in actual use in contact with food and the volume or mass V2 of the sample in contact with food during actual use, based on the actual usage of the sample; pretreatment of the immersion solution; and a blank test: selecting a food simulant that has not been in contact with the sample. The aforementioned migration experiment was repeated, and the pretreatment of the soaking solution was repeated to obtain blank solution A. Determination: Blank solution A and the soaking solution were subjected to high-performance liquid chromatography-quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-QMS-MTMS) to obtain the total ion chromatogram, first-order high-resolution mass spectrum, and corresponding second-order high-resolution mass spectrum. Data was collected once in both positive ion mode and negative ion mode for each batch of solutions. Data processing: Further analysis was performed when the peak area of ​​the extracted ion chromatogram of the unknown substance in the total ion chromatogram of the sample simultaneously met two conditions: it was more than 10 times the peak area of ​​the blank sample and it was more than 1 times the peak area of ​​the structurally similar internal standard. The migration amount X1 of the detected substance was calculated.

[0045]

[0046] In the formula:

[0047] A 目标 The peak area of ​​the target analyte in the chromatogram is determined by screening the target analyte from the soaking solution of the sample to be tested.

[0048] A 内标 The peak area of ​​the internal standard corresponding to the target analyte in the chromatogram of the sample soaking solution to be tested.

[0049] A 0目标The peak area of ​​the target analyte screened from the blank sample soaking solution in the chromatogram;

[0050] A 0内标 The peak area of ​​the internal standard corresponding to the target analyte in the chromatogram of the blank sample soaking solution;

[0051] C 内标 The concentration of the internal standard in the immersion solution of the sample to be tested is expressed in milligrams per liter (mg / L).

[0052] V1 is the volume of the food simulant in the migration experiment;

[0053] S1 is the area of ​​contact between the sample and the food simulant in the migration experiment;

[0054] V2 represents the volume or mass of the sample in contact with food during actual use.

[0055] S2 represents the area of ​​the sample in contact with food during actual use.

[0056] Specifically, before preparing the food simulant, the following reagents are required for measurement: analytical grade acetone, acetic acid, ethanol, methanol, isooctane, and isopropanol; and standards ammonium formate (CH5NO2, CAS No.: 540-69-2) and DNOP-D4 (C 24 H 34 D4O4, CAS No.: 93952-13-7), 4-nitrophenol tetrabutylammonium (C 22 H 40 N2O3, CAS No.: 3002-48-0), arachidic acid-D39(C 20 HD 39 O2 (CAS No.: 39756-32-6) and 4-hydroxy-4'-bromobiphenyl (C 12 H9BrO (CAS No.: 29558-77-8), ultrapure water with a purity >99% and a resistivity of 18.2 MΩ·cm.

[0057] Specifically, in the migration test procedure, the volume of various liquid foods is usually converted into the corresponding mass at a density of 1 kg / L.

[0058] Specifically, during the testing process, a quality calibration must be performed every five injections.

[0059] In some embodiments, specifically, the method for preparing the food simulant includes: preparing an acetic acid solution with water at a volume ratio of 1:24 to obtain an acetic acid solution with a volume fraction of 4%; and preparing an ethanol solution with water at volume ratios of 1:9, 1:4, 1:1, and 19:1 to obtain ethanol solutions with volume fractions of 10%, 20%, 50%, and 95%.

[0060] In some embodiments, the preparation of the internal standard stock solution A specifically includes: weighing the internal standard substance and acetone in proportion, dissolving them in a beaker, transferring them to a volumetric flask to prepare internal standard stock solution A, and storing it in the dark at a temperature of -20°C; the preparation of the internal standard working solution B includes: diluting the internal standard stock solution A with methanol to prepare internal standard working solution B, and storing it in the dark at a temperature of -20°C.

[0061] In some embodiments, specifically, in the pretreatment of the soaking solution, for soaking solutions containing isooctane, accurately transfer 1.00 mL of the soaking solution into a vial, blow it down to 0.50 mL with mild nitrogen gas, add 0.50 mL of isopropanol and a certain volume of internal standard working solution B, mix well, and then perform instrumental analysis; for soaking solutions without isooctane, accurately transfer 1.00 mL of the soaking solution into a vial, add a certain volume of internal standard working solution B, mix well, and then perform instrumental analysis.

[0062] Specifically, since non-targeted screening targets all organic substances that may appear in the migration test solution, the tools and utensils involved in the migration test need to be rinsed with organic solvents before reuse; then, samples are selected for migration experiments to obtain the soaking solution.

[0063] In some embodiments, specifically, the volume of the internal standard working solution B added in the pretreatment of the soaking solution is 10 μL to 100 μL.

[0064] In some embodiments, specifically, the chromatographic column used in the high-performance liquid chromatography-quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-QQMS) is a Waters T3 column or an equivalent column. During chromatographic separation, the mobile phase is 5 mmol / L ammonium formate and methanol of different concentrations, the flow rate is 0.3 mL / min, the column temperature is 40 °C, and gradient elution is also included: 0–8 min, methanol concentration of 10%; 8–17 min, methanol concentration of 100%; 17–20 min, methanol concentration of 10%.

[0065] In some embodiments, specifically, the detector for the high-performance liquid chromatography-quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-quadrupole-time-of-flight high-resolution mass spectrometry) is a quadrupole-time-of-flight high-resolution mass spectrometer, and the mass spectrometry conditions are as follows: Positive ion mode: ion source gas path 1: 55 PSI; curtain gas: 30 PSI; CAD gas: 7; temperature: 550℃; TOF MASS scan range: 100~1500 Da; acquisition mode: IDA; nozzle voltage: 5500 V; declustering voltage: 60 V; collision energy: 10 V; secondary mass spectrometry scan range: 30~1500 Da; declustering voltage: 60 V; collision energy: 35 V; adjustment range: 15 V; Negative ion mode: ion source gas path 1: 55 PSI; curtain gas: 30 PSI; CAD gas: 7; temperature: 550℃; TOF MASS scan range: 100–1500 Da; Acquisition mode: IDA; Nozzle voltage: -4500 V; Declustering voltage: 60 V; Collision energy: 10 V; Secondary mass spectrometry scan range: 30–1500 Da; Declustering voltage: 60 V; Collision energy: 35 V; Adjustment range: 15 V.

[0066] In some embodiments, specifically, the data processing parsing includes: using a library database to perform a spectral library search on the primary high-resolution mass spectrum and the corresponding secondary high-resolution mass spectrum; if the spectral library matching degree is ≥70%, the material structure is confirmed by combining molecular structure and material information; if the spectral library matching degree is <70%, the primary and secondary high-resolution mass spectra of the unknown substance are found in OS Explorer, and then...

[0067] The Formula Finder function, combined with the precise mass number and isotope resolution of primary mass spectrometry, calculates possible molecular formulas and verifies them based on certain mass spectrometry fragmentation rules and the precise mass number of secondary mass spectrometry. Combining material information, common additives, and upstream and downstream processes of the product, it plots possible structures of compounds and verifies them using the Fragment Pane function. In addition, it uses corresponding standard substances to prepare standard solutions for qualitative confirmation, confirming retention time and mass spectra.

[0068] Specifically, the Library database is a self-developed database of the laboratory, the OS Explorer is a data analysis software, the Formula Finder is a molecular formula fitting function, and the Fragment Pane is an automated fragment matching function.

[0069] Example 1

[0070] 1. Experimental Section

[0071] Experimental materials and instruments: Migration test samples: natural bamboo fiber cup, bamboo fiber + PP bowl, bamboo fiber...

[0072] Melamine bowls are available for online purchase; High-performance liquid chromatography-quadrupole time-of-flight mass spectrometry system.

[0073] (HPLC-QTOF), Waters T3 analytical column, 250*4.6mm, 5μm.

[0074] Main reagents: Analytical grade acetone, acetic acid, ethanol, methanol, isooctane, and isopropanol; Standards: ammonium formate (CH5NO2, CAS No.: 540-69-2), DNOP-D4 (C24H34D4O4, CAS No.:

[0075] Ultrapure water with a purity >99% and a resistivity of 18.2 MΩ·cm, containing tetrabutylammonium 4-nitrophenol (C22H40N2O3, CAS No.: 3002-48-0), arachidic acid-D39 (C20HD39O2, CAS No.: 39756-32-6) and 4-hydroxy-4'-bromobiphenyl (C12H9BrO, CAS No.: 29558-77-8).

[0076] Preparation of food simulants: Ethanol and water were mixed at a volume ratio of 19:1 to obtain an ethanol solution with a volume fraction of 95%.

[0077] Migration experiment: In accordance with the requirements of GB 31604.1 and GB 5009.156, three samples, namely natural bamboo fiber cup, bamboo fiber + PP bowl and bamboo fiber + melamine bowl, were immersed in 95% (volume fraction) ethanol at 70℃ for 2 hours using the filling method to carry out the migration experiment and obtain the migration soaking solution.

[0078] Preparation of internal standard stock solution: Accurately weigh 100 mg (accurate to 0.1 mg) each of DNOP-D4, 4-nitrophenol tetrabutylammonium, arachidic acid-D39 and 4-hydroxy-4'-bromobiphenyl into a beaker, dissolve in 50 mL of acetone, transfer to a 100 mL volumetric flask, wash the beaker twice with a small amount of acetone, combine the washings into the volumetric flask, dilute to the mark with acetone, shake well, and prepare internal standard stock solution A with a concentration of 1000 mg / L. Store at -20℃ protected from light.

[0079] Preparation of internal standard working solution: Accurately transfer 10 μL of internal standard stock solution A (1000 mg / L) into a 50 mL volumetric flask, and dilute to the mark with methanol to obtain internal standard working solution B with a concentration of 0.2 mg / L.

[0080] Pretreatment of the soaking solution: Accurately transfer 1.00 mL of soaking solution into a vial, add 50 μL of internal standard working solution B, mix well, and then perform analysis on the instrument.

[0081] Blank test: Prepare a food simulant that has not come into contact with the food contact material according to the migration test and the pretreatment of the soaking solution to obtain a blank soaking solution.

[0082] 2. Analysis Section

[0083] High-performance liquid chromatography-quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-QQMS) was used to determine the total ion chromatogram, first-order high-resolution mass spectrum, and corresponding second-order high-resolution mass spectrum. Data were collected once for each batch of test solutions in both positive and negative ion modes. A mass calibration was performed every 5 injections of sample.

[0084] The chromatographic conditions were as follows: the chromatographic column was a Waters T3 column or an equivalent column; the mobile phase for chromatographic separation was 5 mmol / L ammonium formate (A) + methanol (B); the flow rate was 0.3 mL / min; the column temperature was 40℃; gradient elution was used; and the program is shown in Table 1.

[0085] Table 1 Gradient elution conditions

[0086]

[0087]

[0088] The mass spectrometry conditions are as follows:

[0089] Positive ion mode: Ion source gas path 1: 55 PSI; curtain gas: 30 PSI; CAD gas: 7; temperature: 550℃; TOF MASS scan range: 100~1500 Da; acquisition mode: IDA; nozzle voltage: 5500 V; declustering voltage: 60 V; collision energy: 10 V; secondary mass spectrometry scan range: 30~1500 Da; declustering voltage: 60 V; collision energy: 35 V; adjustment range: 15 V.

[0090] Negative ion mode: Ion source gas path 1: 55 PSI; curtain gas: 30 PSI; CAD gas: 7; temperature: 550℃; TOF MASS scan range: 100~1500 Da; acquisition mode: IDA; nozzle voltage: -4500V; declustering voltage: 60V; collision energy: 10V; secondary mass spectrometry scan range: 30~1500 Da; declustering voltage: 60V; collision energy: 35V; adjustment range: 15V.

[0091] 3. Results and Discussion

[0092] If the peak area of ​​the extracted ion current chromatogram of the unknown substance in the total ion chromatogram of the sample simultaneously meets two conditions—more than 10 times the peak area of ​​the blank sample and more than 1 times the peak area of ​​the internal standard with similar structure—then further analysis is performed. A library search is conducted on the primary high-resolution mass spectrum and the corresponding secondary high-resolution mass spectrum using the Library database. If the matching degree is ≥70%, the substance structure is confirmed by combining molecular structure and material information. If the library matching degree is <70%, the primary and secondary high-resolution mass spectra of the unknown substance are found in OS Explorer. The possible molecular formula is calculated using the Formula Finder function, combined with the precise mass number and isotope fractionation of the primary mass spectrometer, and verified based on certain mass spectrometry fragmentation rules and the precise mass number of the secondary mass spectrometer. Combining material information, common additives, and upstream and downstream processes of the product, the possible structure of the compound is plotted and verified using the Fragment Pane function. If necessary, a standard solution is prepared using appropriate standard substances for qualitative confirmation, confirming the retention time and mass spectrum.

[0093] Limit of quantitation and precision: The limit of detection of this invention was determined by the signal-to-noise ratio method. Figures 1-4 The standard extractable ion chromatograms for DNOP-D4, 4-nitrophenol tetrabutylammonium, arachidic acid-D39, and 4-hydroxy-4'-bromobiphenyl are shown. It can be seen that the signal-to-noise ratio (S / N) of each internal standard at a concentration of 0.01 mg / L is ≥3, indicating that the detection limit of this method is 0.01 mg / kg when the S / V in the migration test is the same as that in actual conditions, and the method has high sensitivity.

[0094] This invention uses DNOP-D4, 4-nitrophenol tetrabutylammonium, arachidic acid-D39 and 4-hydroxy-4'-bromobiphenyl as internal standards. The internal standard stock solution A (1000 mg / L) was serially diluted with methanol to 0.01 mg / L. Six samples were prepared in parallel and their precision was calculated according to the above chromatographic and mass spectrometric conditions. The results are detailed in Table 2.

[0095] The standard deviations of the four internal standards ranged from 2.48% to 5.01%, meeting the requirements of GB / T 27417-2017, indicating that the method of the present invention has good repeatability.

[0096] Table 2 Precision verification of internal standards (n=6)

[0097]

[0098] Measurement of actual samples: The present invention uses the above-mentioned optimized method to conduct migration tests and screenings on three batches of bamboo fiber plastic products purchased from the market. The specific screening results of this embodiment are shown in Table 3 below:

[0099] Table 3. Screening results of three batches of bamboo fiber plastic products

[0100]

[0101]

[0102] As can be seen from the above embodiments, the screening scope of the present invention covers a wide range of additives such as antioxidants, lubricants, antistatic agents, and ultraviolet absorbers, with a wide coverage, a detection limit of 0.01 mg / kg, high sensitivity, and good stability.

[0103] Specifically, this invention provides a method for detecting three phenolic substances in food or food simulants. This method is simple to operate, efficient, specific, and precise. It is suitable for qualitative analysis and quantitative detection of the migration of the three phenolic substances in food contact materials and products. It provides a new method for food safety technical testing in my country and provides risk monitoring and early warning for food enterprises and food contact material manufacturers, which has certain practical significance.

[0104] In summary, this non-targeted screening method for detecting the migration of non-volatile substances in bamboo fiber plastics utilizes high-performance liquid chromatography (HPLC) combined with quadrupole-time-of-flight high-resolution mass spectrometry (QTOF) to rapidly screen the migration amounts of non-volatile substances in bamboo fiber plastic products. The detection limit of this method is 0.01 mg / kg when the S / V in the migration test is consistent with the actual S / V. This screening method is simple to operate, highly stable, and reproducible, aiming to screen out as many potential risk substances as possible. It can comprehensively evaluate the migration amounts of non-volatile substances in bamboo fiber plastic products, ensuring the safety of bamboo fiber plastic products.

[0105] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A non-targeted screening method for detecting the migration of non-volatile substances in bamboo fiber plastics, characterized in that, include: Prepare food simulants, internal standard stock solution A, and internal standard working solution B; Migration test: The vessels involved in the migration test are rinsed with organic solvents and then the migration test is carried out to obtain the soaking solution. In the migration test, the volume V1 of the food simulant and the area S1 of the sample in contact with the food simulant are recorded. According to the actual use of the test sample, the area S2 of the sample in contact with the food in actual use and the volume or mass V2 of the sample in contact with the food in actual use are recorded. Pretreatment of the soaking solution; Blank test: Select a food simulant that has not been in contact with the sample and repeat the above migration test, and repeat the above pretreatment of the soaking solution to obtain blank test solution A; Determination: Blank test solution A and soaking solution were subjected to high performance liquid chromatography-quadrupole-time-of-flight high resolution mass spectrometry to obtain total ion chromatogram, first-level high resolution mass spectrum and corresponding second-level high resolution mass spectrum. Data were collected once each for each batch of test solution in positive ion mode and negative ion mode. Data processing: If the peak area of ​​the extracted ion chromatogram of the unknown substance in the total ion chromatogram of the sample simultaneously meets two conditions, namely, that it is more than 10 times the peak area of ​​the blank sample and more than 1 times the peak area of ​​the internal standard with similar structure, then proceed to the next step of analysis. Calculate the migration amount X1 of the detected substance: In the formula: A 目标 The peak area of ​​the target analyte in the chromatogram is determined by screening the target analyte from the soaking solution of the sample to be tested. A 内标 The peak area of ​​the internal standard corresponding to the target analyte in the chromatogram of the sample soaking solution to be tested. A 0目标 The peak area of ​​the target analyte screened from the blank sample soaking solution in the chromatogram; A 0内标 The peak area of ​​the internal standard corresponding to the target analyte in the chromatogram of the blank sample soaking solution; C 内标 The concentration of the internal standard in the immersion solution of the sample to be tested is expressed in milligrams per liter. V1 is the volume of the food simulant in the migration experiment; S1 is the area of ​​contact between the sample and the food simulant in the migration experiment; V2 represents the volume or mass of the sample in contact with food during actual use. S2 represents the area of ​​the sample in contact with food during actual use.

2. The detection method as described in claim 1, characterized in that, The method for preparing the food simulant includes: mixing acetic acid and water at a volume ratio of 1:24 to obtain an acetic acid solution with a volume fraction of 4%; and mixing ethanol and water at volume ratios of 1:9, 1:4, 1:1, and 19:1 to obtain ethanol solutions with volume fractions of 10%, 20%, 50%, and 95%.

3. The detection method as described in claim 1, characterized in that, The preparation of the internal standard stock solution A includes: weighing the internal standard substance and acetone in proportion, dissolving them in a beaker, transferring them to a volumetric flask to prepare internal standard stock solution A, and storing it in the dark at a temperature of -20℃. The preparation of the internal standard working solution B includes: diluting the internal standard stock solution A with methanol to prepare the internal standard working solution B, and storing it in the dark at a temperature of -20°C.

4. The detection method as described in claim 3, characterized in that, The internal standard includes one or more of DNOP-D4, 4-nitrophenol tetrabutylammonium, arachidic acid-D39, and 4-hydroxy-4'-bromobiphenyl. The mass ratio of each internal standard to the volume of acetone is 100 mg: 100 mL. The concentration of the internal standard stock solution A is 1000 mg / L. It is stored in the dark at a temperature of -20°C.

5. The detection method as described in claim 1, characterized in that, In the pretreatment of the soaking solution, for soaking solutions containing isooctane, accurately transfer 1.00 mL of soaking solution into a vial, blow it down to 0.50 mL with mild nitrogen gas, add 0.50 mL of isopropanol and a certain volume of internal standard working solution B, mix well and then perform instrumental detection and analysis. For immersion solutions that do not contain isooctane, accurately transfer 1.00 mL of the immersion solution into a vial, add a certain volume of internal standard working solution B, mix well to obtain the immersion solution, and then perform instrumental analysis.

6. The detection method as described in claim 5, characterized in that, The volume of the internal standard working solution B added during the pretreatment of the immersion solution is 10 μL to 100 μL.

7. The detection method as described in claim 1, characterized in that, The high-performance liquid chromatography-quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-QPS-MS) method uses a Waters T3 column or an equivalent column. The mobile phase for chromatographic separation is 5 mmol / L ammonium formate and methanol of varying concentrations, with a flow rate of 0.3 mL / min and a column temperature of 40 °C. Gradient elution is also included. From 0 to 8 minutes, the methanol concentration was 10%. The methanol concentration was 100% for 8–17 minutes. 17–20 min, methanol concentration is 10%.

8. The detection method as described in claim 1, characterized in that, The detector used in the high-performance liquid chromatography-quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-QLP-TFO) method is a quadrupole-time-of-flight high-resolution mass spectrometer, and the mass spectrometry conditions are as follows: Positive ion mode: Ion source gas path 1: 55 PSI; curtain gas: 30 PSI; CAD gas: 7; Temperature: 550℃; TOF MASS scan range: 100~1500Da; Acquisition mode: IDA; Nozzle voltage: 5500V; Declustering voltage: 60V; Collision energy: 10V; Secondary mass spectrometry scan range: 30~1500Da; Declustering voltage: 60V; Collision energy: 35V; Adjustment range: 15V; Negative ion mode: Ion source gas path 1: 55 PSI; curtain gas: 30 PSI; CAD gas: 7; Temperature: 550℃; TOF MASS scan range: 100~1500Da; Acquisition mode: IDA; Nozzle voltage: -4500V; Declustering voltage: 60V; Collision energy: 10V; Secondary mass spectrometry scan range: 30~1500Da; Declustering voltage: 60V; Collision energy: 35V; Adjustment range: 15V.

9. The detection method as described in claim 1, characterized in that, The data processing includes parsing: The Library database was used to search for the primary high-resolution mass spectra and their corresponding secondary high-resolution mass spectra. If the library matching degree was ≥70%, the material structure was confirmed by combining molecular structure and material information. If the library matching degree was <70%, the primary and secondary high-resolution mass spectra of the unknown substance were found in OS Explorer. The possible molecular formula was calculated using the Formula Finder function, along with the precise mass number and isotope fractionation of the primary mass spectra, and then verified based on certain mass spectrometry fragmentation rules and the precise mass number of the secondary mass spectra. By combining material information, common additives, and upstream and downstream processes of the product, the possible structures of the compound are plotted and verified using the FragmentPane function. Additionally, standard solutions were prepared using appropriate standard substances for qualitative confirmation, including confirmation of retention time and mass spectra.

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