CN114113422B - Pretreatment method for monitoring content or migration amount of endocrine disruptors in plastic food packaging material - Google Patents
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Abstract
The invention belongs to the technical field of environmental monitoring, and discloses a pretreatment method for monitoring the content or migration amount of endocrine disruptors in a plastic food packaging material. The invention adopts the mode of heating and melting the food packaging material, cooling and remolding to form standard weight or volume again, so that the internal standard substance can permeate into the solid sample to form uniform mixing type standard addition, the sample prepared by the method can realize the same extraction of the internal standard substance and the target substance in the extraction process, the substance detection rate is improved, the size of matrix effect and the extraction capacity of the extractant are accurately displayed, the actual hazard of the sample is truly reflected, the error caused by the difference of the states of the internal standard substance and the target substance in the extraction process is avoided, the accuracy is improved by 10-30%, and the sampling deviation can be avoided by adopting the standard weight or the standard volume.
Description
Technical Field
The invention belongs to the technical field of environmental monitoring, and particularly relates to a pretreatment method for monitoring the content or migration amount of endocrine disruptors in a plastic food packaging material.
Background
The relevant regulations in the united states state that migration of actives in food packaging materials into food is a significant cause of food safety issues and define such actives as indirect food additives, and thus endocrine disruptors have gained widespread attention to researchers as a major role in food packaging. In China, the problem of food packaging has become a research hotspot in recent years. The food packaging materials in China mainly comprise plastic products, paper products, composite packages, metal, glass and the like, but with the acceleration of the living pace of residents, the consumption of the masses on fast food is stronger, and the plastic packages and the paper packages occupy most markets. In the production process of plastics and paper, plasticizers, dyes, bleaching agents, curing agents and the like are added, and the generation of endocrine disruptors is unavoidable.
In the current detection experiments of endocrine disruptors (such as bisphenol, polychlorinated biphenyl, phthalic dibasic esters and the like), quantitative analysis is mainly carried out on components to be detected in a sample by an internal standard method. The internal standard method is to add quantitative pure substances as internal standard substances into a sample mixture to be analyzed, then to carry out chromatographic analysis on a sample containing the internal standard substances, and to calculate the content of the component to be detected by monitoring the peak areas of the internal standard substances and the component to be detected. This method is also commonly used in experiments on migration of harmful chemicals within food packaging materials.
At present, in an experiment for detecting endocrine disruptors existing in food packaging materials, methods such as solid phase extraction, ultrasonic extraction, rapid solvent extraction and the like are mainly adopted. The method is mainly characterized in that the migration quantity of pollutants in the material is obtained by measuring the difference of the concentration of substances before and after extracting liquid of food and packaging materials, so that the migration capacity of the material is judged. However, the internal standard method needs to add the marker of the target compound into the sample, the common method is a direct addition mode, and the internal standard substance is attached to the surface of the sample after standing for a period of time. More importantly, the methods can only obtain a rapid extraction result under a single environment condition, and cannot realize long-term detection of pollutants in food packaging materials under the condition of multi-factor interference, and cannot exclude the influence of the pollutant content of foods except the food packaging materials. Therefore, a novel method for monitoring the migration quantity of endocrine disruptors in food packaging materials is found, so that more accurate data support is provided for related departments, and resident food safety is guaranteed.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the primary aim of the invention is to provide a novel pretreatment method for monitoring the content or migration amount of endocrine disruptors in food packaging materials, which adds a process of remolding the packaging materials in the existing endocrine disruptor detection technology, so that internal standard substances are fully fused into the packaging materials, thereby ensuring that the accurate measurement of the content or migration amount of the endocrine disruptors in the food packaging materials is realized under the influence of various environmental conditions, and solving the defect that the internal standard method is not well mixed when being used for solid samples.
It is a further object of the present invention to provide the use of the pretreatment method described above for monitoring the content or migration of endocrine disruptors in food packaging materials.
The aim of the invention is achieved by the following scheme:
a pretreatment method for monitoring endocrine disruptors content or migration in plastic food packaging material comprising heat dissolution and remodeling.
Wherein the heating dissolution means: wiping off surface pollutants from a food packaging material to be measured, washing, drying, cutting into fragments or grinding and crushing, taking out a sample with standard weight (such as 1-5 g) after uniform mixing, putting the sample into a round glass culture dish, adding an internal standard mixed solution corresponding to the endocrine disrupter to be measured, covering a cover of the glass culture dish, standing to enable the internal standard to be fully and uniformly mixed on the surface of the sample, and then putting the sample into a muffle furnace to heat to enable the packaging material to be in a molten state;
wherein the remodeling means: taking out the food packaging material in a molten state, naturally cooling the food packaging material at room temperature, and storing the food packaging material in a refrigerator so as to take out the sample for subsequent examination.
The food packaging material is one of a plastic snack box, a plastic yoghurt packaging box and a plastic soda bottle.
The mixed internal standard solution refers to a mixed solution of internal standard substances which are added in the pretreatment process of a sample and correspond to the to-be-detected substances when the internal standard method is used for measuring the substances, and is generally pure substances of carbon or deuterium, and the content of the to-be-detected components is measured in a comparison mode by taking the amount of the pure substances as a standard;
the food packaging material added into the round glass culture dish and the dosage of the internal standard mixed solution satisfy the following conditions: and placing 1-5g of each sample into a round glass culture dish, and correspondingly adding 50 mu L of internal standard mixed solution, wherein the optimal concentration range of the internal standard in the internal standard mixed solution is not lower than the concentration of the component to be detected and not more than twice the concentration value of the component to be detected.
The heating-induced packaging material is in a molten state, namely, the packaging material is heated for 5-15 minutes at 150-200 ℃.
The pretreatment method is applied to detection and monitoring of the content or migration amount of endocrine disruptors in the plastic food packaging material.
A method of monitoring the content of endocrine disruptors in a plastic food packaging material comprising the steps of:
(1) Carrying out ultrasonic extraction on the pretreated food packaging material;
(2) And detecting the extracted sample by a gas chromatography-mass spectrometer or a liquid chromatography-mass spectrometer.
The ultrasonic extraction in the step (1) refers to a three-time extraction process, wherein three-time ultrasonic extraction steps are as follows: taking out the cooled round slice, re-fragmenting the round slice, placing the round slice into a centrifuge tube, adding an extraction solvent 1, swirling, performing ultrasonic extraction, centrifuging in the centrifuge after swirling again to obtain a supernatant 1, adding an extraction solvent 2 into the centrifuge tube, swirling, performing ultrasonic extraction, centrifuging in the centrifuge after swirling again to obtain a supernatant 2, continuously adding an extraction solvent 3 into the centrifuge tube, swirling, performing ultrasonic extraction, centrifuging in the centrifuge after swirling again, collecting the supernatant 3, and combining the supernatant 1, the supernatant 2 and the supernatant 3. Taking all supernatant fluid, passing through a 0.22 mu m nylon filter membrane, blowing nitrogen until the supernatant fluid is nearly dry, and fixing the volume to 0.5ml by using normal hexane or methanol to obtain a sample which is measured by the machine in the step (3).
The extraction solvent 1, the extraction solvent 2 and the extraction solvent 3 in the step (1) can be selected to be the optimal extractant combination according to the substances to be detected, and can be one or more mixtures selected from ethyl acetate, n-hexane, acetone and dichloromethane relatively independently;
preferably, the extraction solvent 1, the extraction solvent 2 and the extraction solvent 3 in the step (1) are all ethyl acetate; or the extraction solvent 1, the extraction solvent 2 and the extraction solvent 3 in the step (1) are respectively n-hexane, acetone and a mixture of n-hexane and acetone in a volume ratio of 1:1.
The dosage of the extraction solvent in the step (1) needs to ensure that the solid sample is fully covered by the solvent, and the liquid level of the solvent is about 0.5 cm to 1cm higher than that of the solid sample.
More preferably, the ultrasonic extraction in the step (1) is a three-time extraction process, wherein three ultrasonic extraction steps are as follows: taking out 2g of cooled round slices, re-fragmenting the round slices, placing the round slices into a centrifuge tube, adding 4ml of extraction solvent 1, swirling the round slices for 20s, performing ultrasonic extraction for 30min, centrifuging the round slices in the centrifuge tube for 5min at the speed of 4000rpm after swirling the round slices again, obtaining supernatant 1, adding 3ml of extraction solvent 2 into the centrifuge tube, performing ultrasonic extraction for 20s, centrifuging the round slices for 20s at the speed of 4000rpm after swirling the round slices again, obtaining supernatant 2, continuously adding 3ml of extraction solvent 3 into the centrifuge tube, swirling the round slices for 20s, performing ultrasonic extraction for 30min, centrifuging the round slices in the centrifuge tube for 5min at the speed of 4000rpm after swirling the round slices again, obtaining supernatant 1, supernatant 2 and supernatant 3 by combining the round slices. Taking all supernatant, passing through a 0.22 mu m nylon filter membrane, blowing nitrogen to near dryness, and fixing the volume to 0.5ml by using normal hexane or methanol to obtain a sample which is measured by the machine in the step (2).
In the step (2), a gas chromatography-mass spectrometer or a liquid chromatography-mass spectrometer can be selected for detection according to the type of the substance to be detected;
the gas chromatography conditions in the gas chromatography mass spectrometer described in step (2) are preferably:
chromatographic column: model specification Rtx-5MS (30 m x 0.25mm i.d.:0.25 μm) from Agilent, inc;
carrier gas: high purity helium (> 99.999%);
sample injection mode: not split;
sample injection volume: 1 μl;
the sample inlet temperature is: 260 ℃;
chromatographic column temperature program: the initial temperature is 60 ℃, the temperature is kept for 2min, then the temperature is increased to 280 ℃ at the speed of 60 ℃/min, the temperature is kept for 2min, and then the temperature is increased to 290 ℃ at the speed of 10 ℃/min, and the temperature is kept for 12 min;
the mass spectrometry conditions in the gas chromatograph-mass spectrometer described in step (2) are preferably:
chromatographic column interface and ion source temperature: 230 ℃ and 280 ℃;
solvent delay time: 3min
Detection voltage: 0.1kv relative to the tuning result.
The conditions of liquid chromatography in the liquid chromatography mass spectrometer in step (2) are preferably:
chromatographic column: produced by sameimer, usa (Thermo Scientific), model number Betasil C18 (100 mm x 2.1 mm), filler particle size 5 μm;
mobile phase: the phase A is methanol, the phase B is pure water, and the total flow rate of the phase A and the phase B is 0.3ml/min;
sample injection amount of automatic sample injector: 5 μl;
column oven temperature: 40 ℃;
the elution mode of the target compound is gradient elution, the total duration is 15min, and the elution program is as follows: 0-2min, and the proportion of phase B is 0-15%;2-3min, wherein the proportion of phase B is 15% -60%;3-5min, the proportion of phase B is 60% -70%;5-6.5min, and the proportion of the phase B is 70% -80%;6.5 to 7.5 minutes, and the proportion of the phase B is 80 to 90 percent; 7.5 to 8.5min, and the proportion of the phase B is 90 to 99 percent; 8.5-10min, the proportion of B is kept to be 99%;10-10.5min, wherein the proportion of the phase B is 99% -15%;10.5-15, the proportion of the phase B is kept to be 15%, and the process is finished.
The relevant parameters of the mass spectrum in the liquid chromatography mass spectrometer in the step (2) are as follows:
mass spectrometry scan mode: a multi-reaction monitor (Multiple Reaction Monitoring, MRM);
ionization mode: electrospray Ionization (ESI);
the detection mode is as follows: negative ion mode (Negative);
ion source Temperature (TEM): 550 ℃;
electrospray Voltage (IS): -4500V;
curtain Gas (CUR): 25.0Psi;
collision Gas (CAD): 7.0Psi;
atomizing Gas (Ion Source Gas 1): 35.0Psi;
auxiliary Gas (Ion Source Gas 2): 60Psi.
A method of monitoring the migration of endocrine disruptors in a food packaging material comprising the steps of:
(1) Performing simulated soaking on the pretreated sample;
(2) And detecting the simulated soaked gas chromatography-mass spectrometer or the liquid chromatography-mass spectrometer.
The simulated soaking in the step (1) means that the pretreated sample is soaked in 4% (v/v) acetic acid solution for culture, 5ml of the sample is absorbed by a syringe in a screw test tube after the culture, 5ml of normal hexane or ethyl acetate solution is added, the mixture is uniformly mixed by vortex and then is subjected to ultrasonic treatment for 30min, the mixture is placed in a centrifugal machine for centrifugal treatment for 5min after vortex again, the speed is 4000rpm, the supernatant is taken, gentle nitrogen is blown to be nearly dry, and the normal hexane or methanol is used for fixing the volume to 0.5ml, so that the sample is measured by the step (2).
The culturing in the step (1) refers to culturing at 25-75 ℃ for 1-10h;
the parameters of the step (2) are the same as those of the step (2) for measuring the content of endocrine disruptors in the food packaging material.
Compared with the prior art, the invention has the following advantages:
compared with the traditional labeling method, the method has the advantages that the food packaging material is heated and melted, and cooled and remolded to form the standard weight or volume again, so that the internal standard substance can permeate into the solid sample to form the uniform-mixing labeling, the sample prepared by the method can be extracted from the internal standard substance and the target substance simultaneously in the extraction process, the substance detection rate is improved, the size of the matrix effect and the extraction capacity of the extractant are accurately displayed, the actual hazard of the sample is truly reflected, the error caused by the difference of the states of the internal standard substance and the target substance in the extraction process is avoided, the accuracy is improved by 10-30%, and the sampling deviation can be avoided by adopting the standard weight or the standard volume.
Drawings
FIG. 1 is a comparative drawing of plastic food packaging material samples before and after remodeling, wherein (a) represents a plastic snack box, (b) represents a plastic yogurt package, and (c) represents a plastic soda bottle.
FIG. 2 shows the internal standard recovery and matrix addition recovery of the samples measured in example 1, wherein (a) is the result of the content measurement recovery and (b) is the result of the migration measurement recovery.
FIG. 3 shows the internal standard recovery and matrix addition recovery of the samples measured in example 2, wherein (a) is the result of the content measurement recovery and (b) is the result of the migration measurement recovery.
FIG. 4 is a graph showing the comparison of the detection rate of substances in the plastic food packaging material after the remodeling in examples 1 and 2, wherein (a) represents example 1 and (b) represents example 2.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but embodiments of the present invention are not limited thereto. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The reagents used in the examples are commercially available as usual unless otherwise specified.
Example 1
The phthalate compounds are additives with the largest dosage in plastic products, and are also environmental endocrine disruptors, and researches show that the substances have reproduction toxicity, carcinogenicity and teratogenicity and are accumulated to a certain extent to cause serious harm to human health. The method can basically know the phthalate content and the phthalate migration rule in the common food packaging material by measuring the phthalate concentration and the phthalate migration amount in the specific food contact material of the plastic packaging box, including the common plastic snack box, the plastic soda bottle and the plastic sour milk bottle; aims to provide a certain reference basis for the standard use of the food packaging material in daily life and industrial application. The comparative figures of plastic food packaging material samples before and after remodeling are shown in fig. 1, wherein (a) represents a plastic snack box, (b) represents a plastic yogurt packaging box, (c) represents a plastic soda bottle, the left side represents the plastic soda bottle before remodeling, and the right side represents the plastic yogurt packaging box after remodeling.
(1) Experimental material for migration research of phthalate plasticizers in plastic food packaging boxes
(1.1) laboratory instruments and materials
(1.1.1) apparatus and consumables
The main instruments used in this example are shown in Table 1, and include pretreatment equipment and chemical analysis equipment.
Table 1 basic information of laboratory instruments and equipment
(1.1.2) Standard substance
Phthalate esters: n-butyl phthalate (DBP), di-n-octyl phthalate (DNOP), 2-ethylhexyl phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), dicyclohexyl phthalate (DCHP), diisobutyl phthalate (DIBP); the internal standard substances are 7 deuterated compounds, namely d4-DMP, d4-DEP, d4-DBP, d4-DIBP, d4-DCHP, d4-DEHP and d4-DNOP.
(1.1.3) chemical Agents
The chemicals used in the experiments were all HPLC chromatographic grade, including ultrapure water, n-hexane, acetone, all purchased from Fisher Scientific (Waltham, mass., USA). Glacial acetic acid, prepared as a 4% acetic acid solution, was analytically pure and purchased from the company, inc. of Tianjin far chemical reagent.
(1.1.4) other materials
The diameter of the round glass culture dish is 35mm; the nylon filter membrane has a diameter of 13mm and a pore diameter of 0.22 mu m, and the manufacturer is Shanghai Anpu experiment technology Co., ltd; the disposable sterile syringe has the specification of 1ml, and the manufacturer is Changzhou Yuekang medical instruments Co., ltd; dust-free paper; a 50ml glass beaker; a 12ml screw bottle; a 250ml volumetric flask; a glass rod; and scissors.
(1.1.5) preparation of Standard solution
Preparing standard storage solution: 7 PAES standard substances are diluted with n-hexane to prepare standard storage solutions with the concentration of each substance being 10 mug/ml, the corresponding deuterated internal standard compound is prepared into mixed storage solutions with the concentration of each deuterated internal standard compound being 2 mug/ml, and the solutions are stored at the low temperature of 4 ℃.
Standard working curve: and quantifying by adopting an internal standard method, wherein all standard working curves comprise a series of target compounds with gradient concentrations and corresponding internal standard substances with fixed concentrations. The standard curve is drawn according to peak area and mass concentration, the gradient concentration of 7 PAES standard curves is 5-2000ng/ml, wherein the concentration of 7 deuterated internal standard compounds is 200ng/ml.
(1.1.6) preparation of simulated soaking solution
4% acetic acid solution: taking 10m L glacial acetic acid, diluting and transferring to a 250m L volumetric flask by using ultrapure water, and uniformly mixing and standing after the volumetric flask is fixed.
(1.2) quality assurance and quality control
Each batch of samples is added with 3 blank controls, 3 blank labeling and 3 matrix labeling samples, and the blank labeling recovery rate and the matrix labeling recovery rate are calculated; the glassware used in the experiment is ultrasonically cleaned by methanol and soaked in alkali liquor for more than 24 hours, then fished out and cleaned by ultrapure water for 3 times, then put into an oven for drying, and finally burned for 4 hours at 400 ℃ by a muffle furnace for use, and before the use, the glassware is further rinsed by n-hexane for 2 times, so that the experiment process is ensured to be free from excessive pollution.
(2) The method for researching migration of phthalate plasticizer in plastic food packaging box
(2.1) sample pretreatment and instrumental analysis
(2.1.1) pretreatment Process of sample for determining phthalate content in Plastic food packaging box
(2.1.1.1) first, surface contaminants of the plastic food packaging box were wiped off with dust-free paper, rinsed with ultrapure water and dried. Cutting the sample to be detected according to the proportion of 1:10 according to different parts of the plastic packaging box, manually cutting the sample to fragments with the size close to 0.2cm and 0.2cm, and uniformly mixing;
(2.1.1.2) weighing 2g of the uniformly mixed sample, putting the sample into a round glass vessel with the bottom diameter of 3.5cm, adding 100ng of mixed internal standard (namely, 100ng of all seven internal standard substances), covering the glass vessel, standing for 30min, putting the sample into an electric heating constant temperature box for heating at 200 ℃, taking out the sealed glass vessel after 10min, cooling at room temperature, and putting the glass vessel into a refrigerator for half an hour;
(2.1.1.3) taking out the cooled and solidified plastic sample, crushing the sheet again, putting the sheet into a 12ml screw bottle, adding 4ml of extracting agent n-hexane, swirling for 20s, then carrying out ultrasonic treatment for 30min, swirling again, putting the sample into a centrifuge, centrifuging for 5min at 4000rpm, and taking supernatant;
(2.1.1.4) the volume of the extractant added in the second extraction process and the third extraction process is 3ml, and the extractant is acetone and n-hexane respectively: acetone=1:1, the extraction steps are the same as the first, and the supernatants obtained by three extractions are combined;
(2.1.1.5) blowing the extract to near dryness by using gentle nitrogen, adding 0.5ml of n-hexane, and then passing through a Ni Long Lvtou to enter a GC-MS (gas chromatography-mass spectrometry) for detection;
(2.1.2) pretreatment of samples for determining the migration amount of phthalate esters in plastic cutlery boxes at different temperatures and different storage times
(2.1.2.1) the surface contaminants of the plastic cutlery box were first wiped off with dust-free paper, rinsed with ultrapure water and dried. Cutting the sample to be detected according to the ratio of 1:10 according to different parts of the plastic cutlery box, manually cutting the sample to fragments with the size close to 0.2cm and 0.2cm, and uniformly mixing;
(2.1.2.2) weighing 2g of the uniformly mixed sample, putting the sample into a round glass vessel with the bottom diameter of 3.5cm, adding 20ng of mixed internal standard (namely, the using amount of 7 internal standard substances is 20 ng), covering the glass vessel, standing for 30min, putting the sample into an electric heating constant temperature box for heating at 200 ℃, taking out the sealed glass vessel after 10min, standing for cooling, and putting the glass vessel into a refrigerator for freezing for half an hour;
(2.1.2.3) taking out 15 cooled and solidified plastic samples, uniformly dividing into 3 parts, respectively placing three parts of 5 cooled and solidified plastic samples into three 50ml glass beakers, adding 40ml of 4% acetic acid solution into the glass beakers, uniformly stirring by using a glass rod, wrapping the cup opening by using tinfoil, respectively placing into a baking oven at 25 ℃, 50 ℃ and 75 ℃, sequentially taking out samples at corresponding time when the storage time is 1h, 2h, 5h, 8h and 10h, sucking 5ml of samples into a screw test tube by using a 1ml syringe, adding 5ml of n-hexane, uniformly vortex, performing ultrasonic treatment for 30min, centrifuging for 5min after vortex again, taking supernatant at 4000rpm, blowing to near dryness by using soft nitrogen, fixing the volume by using n-hexane to 0.5ml, and entering a GC-MS to be tested.
(3) Instrumental analysis
(3.1) chromatographic conditions:
chromatographic column: model specification Rtx-5MS (30 m x 0.25mm i.d.:0.25 μm) from Agilent, inc;
carrier gas: high purity helium (> 99.999%);
sample injection mode: not split;
sample injection volume: 1 μl;
sample inlet temperature: 260 ℃;
chromatographic column temperature program: the initial temperature is 60 ℃, the temperature is kept for 2min, then the temperature is increased to 280 ℃ at the speed of 60 ℃/min, the temperature is kept for 2min, and then the temperature is increased to 290 ℃ at the speed of 10 ℃/min, and the temperature is kept for 12 min;
(3.2) Mass Spectrometry conditions:
chromatographic column interface and ion source temperature: 230 ℃ and 280 ℃;
solvent delay time: 3min;
detection voltage: 0.1kv relative to the tuning result.
The qualitative and quantitative reference ions of 7 target compounds of phthalate and corresponding 7 deuterated internal standard compounds are shown in table 2.
Table 2 phthalate 7 target compounds and corresponding 7 deuterated internal standard compounds qualitative and quantitative reference ions
(4) Analysis of results
Migration refers to the amount of material transferred from the medium to the environment under certain conditions. And integrating the data detected by the machine by software to obtain the content or migration quantity of the corresponding endocrine disruptors.
The total internal standard recovery rate and the total sample matrix standard recovery rate of all the test samples in this embodiment are shown in fig. 2, and the internal standard for determining the content and the migration amount of the phthalate dibasic ester by the method in this embodiment is fully integrated into the samples, the internal standard recovery rate is inevitably reduced, but the average value is above 70%, the requirement for the internal standard recovery rate is met, the blank standard recovery rate and the matrix standard recovery rate are between 70% and 135%, the standard deviation is between 10% and 25%, and the method stability is good. And the detection rate of the substances is improved by about 10 percent, and the specific details are shown in (a) in fig. 4, wherein before remolding, the plastic sample is directly subjected to the pretreatment process of adding marks without heating to dissolve and remolding.
Example 2
Bisphenol materials are additives for the manufacture of polycarbonate plastics, epoxy resins and phenolic resins, and are widely found in food and beverage packaging materials or containers. Bisphenol A is a typical exogenous endocrine disrupter which, when absorbed and accumulated by the human body, alters the hormone level of the human body and causes harm to the reproductive system of the human body, and has been a negative effect even at low doses and has received extensive attention from researchers. Diet is generally considered the most important route of exposure, and thus leaching of bisphenols from food packaging materials needs to be more accurately measured. The embodiment of the invention basically knows the content and migration rule of bisphenol substances in the common food packaging material by measuring the concentration and migration amount of bisphenol in the specific food contact material, namely the plastic snack box, and perfects the existing measuring method.
(1) Experimental materials and methods for migration studies of bisphenol in Plastic snack boxes according to examples of the invention
(1.1) laboratory instruments and materials
(1.1.1) apparatus and consumables
The main instruments used in the examples of the present invention are shown in Table 3, including pretreatment equipment and chemical analysis equipment.
TABLE 3 basic information of laboratory instruments and devices
(1.1.2) Standard substance
Bisphenol: bisphenol a (BPA), bisphenol S (BPS), bisphenol F (BPF), bisphenol AF (BPAF), bisphenol B (BPB); the internal standard substance is 5 kinds of carbo-compounds, respectively 13 C 12 -BPA、 13 C 12 -BPS、 13 C 12 -BPF、 13 C 12 -BPAF、 13 C 12 -BPB。
(1.1.3) chemical Agents
The chemicals used in the experiments were all HPLC chromatographic grade, including ultrapure water, methanol, ethyl acetate, all purchased from Fisher Scientific (Waltham, mass., USA). Glacial acetic acid, prepared as a 4% acetic acid solution, was analytically pure and purchased from the company, inc. of Tianjin far chemical reagent.
(1.1.4) other materials
The diameter of the round glass culture dish is 35mm; the nylon filter membrane has a diameter of 13mm and a pore diameter of 0.22 mu m, and the manufacturer is Shanghai Anpu experiment technology Co., ltd; the disposable sterile syringe has the specification of 1ml, and the manufacturer is Changzhou Yuekang medical instruments Co., ltd; dust-free paper; a 50ml glass beaker; a 12ml screw bottle; a 250ml volumetric flask; a glass rod; and scissors.
(1.1.5) preparation of Standard solution
Preparing standard storage solution: 5 kinds of BPs standard substances are diluted by methanol to prepare standard storage solutions with the concentration of each substance being 10 mug/ml, 5 kinds of corresponding carbon-substituted internal standard compounds are prepared into mixed internal standard storage solutions with the concentration of each substance being 2 mug/ml, and the solutions are stored at the low temperature of 4 ℃.
Standard working curve: and quantifying by adopting an internal standard method, wherein all standard working curves comprise a series of target compounds with gradient concentrations and corresponding internal standard substances with fixed concentrations. And drawing a standard curve according to peak area and mass concentration, wherein the gradient concentration of 5 BPs standard curves is 0.1-400ng/ml, and the concentration of 5 carbon-substituted internal standard compounds is 50ng/ml.
(1.1.6) preparation of simulated soaking solution
4% acetic acid solution: taking 10m L glacial acetic acid, diluting and transferring to a 250m L volumetric flask by using ultrapure water, and uniformly mixing and standing after the volumetric flask is fixed.
(1.2) quality assurance and quality control
Each batch of samples is added with 3 blank controls, 3 blank labeling and 3 matrix labeling samples, and the blank labeling recovery rate and the matrix labeling recovery rate are calculated; the glassware used in the experiment is ultrasonically cleaned by methanol and soaked in alkali liquor for more than 24 hours, then fished out and cleaned by ultrapure water for 3 times, then put into an oven for drying, and finally burned for 4 hours at 400 ℃ in a muffle furnace for use, and before use, the glassware is further rinsed by methanol for 2 times, so that excessive pollution is avoided in the experiment process.
(2) Experimental details of migration studies of bisphenol in Plastic snack boxes
(2.1) sample pretreatment and instrumental analysis
(2.1.1) pretreatment Process for bisphenol content determination sample in Plastic cutlery box
(2.1.1.1) first, the surface contaminants of the plastic cutlery box were wiped off with dust-free paper, rinsed with ultrapure water and dried. Cutting the sample to be detected according to the ratio of 1:10 according to different parts of the plastic cutlery box, manually cutting the sample to fragments with the size close to 0.2cm and 0.2cm, and uniformly mixing;
(2.1.1.2) weighing 2g of the uniformly mixed sample, putting the sample into a round glass vessel with the bottom diameter of 3.5cm, adding 25ng of mixed internal standard stock solution, covering a cover of the glass vessel, standing for 30min, putting the sample into an electric heating incubator for heating at 200 ℃, taking out the sealed glass vessel after 10min, and standing for cooling;
(2.1.1.3) taking out the cooled and solidified plastic sample, crushing the sheet again, putting the sheet into a 12ml screw bottle, adding 4ml of extracting agent ethyl acetate, swirling for 20s, then carrying out ultrasonic treatment for 30min, swirling again, putting the sample into a centrifuge, centrifuging for 5min at 4000rpm, and taking supernatant;
(2.1.1.4) adding 3ml of extracting agent in the second and third extraction processes, wherein the extracting agent is ethyl acetate, the extraction steps are the same as those of the first extraction process, and finally, the supernatants obtained by the three extraction processes are combined;
(2.1.1.5) blowing the extract to near dryness by using gentle nitrogen, adding 0.5ml of methanol, and then filtering the nylon filter head to enter LC/MS/MS to be detected;
(2.1.2) pretreatment of samples for measuring migration amount of bisphenol in plastic cutlery box at different temperatures and different storage times
(2.1.2.1) the surface contaminants of the plastic cutlery box were first wiped off with dust-free paper, rinsed with ultrapure water and dried. Cutting the sample to be detected according to the ratio of 1:10 according to different parts of the plastic cutlery box, manually cutting the sample to fragments with the size close to 0.2cm and 0.2cm, and uniformly mixing;
(2.1.2.2) weighing 2g of the uniformly mixed sample, putting the sample into a round glass vessel with the bottom diameter of 3.5cm, adding 5ng of mixed internal standard stock solution, covering a cover of the glass vessel, standing for 30min, putting the sample into an electric heating incubator for heating at 200 ℃, taking out the sealed glass vessel after 10min, and standing for cooling;
(2.1.2.3) taking out 15 cooled and solidified plastic samples, uniformly dividing into 3 parts, adding three parts of 5 cooled and solidified plastic samples into three 50ml glass beakers respectively, adding 40ml of 4% acetic acid solution into the glass beakers, uniformly stirring by using a glass rod, wrapping the cup openings by using tinfoil, respectively placing into a baking oven at 25 ℃ and 50 ℃ and 75 ℃, sequentially taking out samples at corresponding time when the storage time is 1h, 2h, 5h, 8h and 10h, sucking 5ml of samples into a screw test tube by using a 1ml syringe, adding 5ml of ethyl acetate, carrying out ultrasonic treatment for 30min after vortex uniformly mixing, centrifuging for 5min after vortex again, taking supernatant at 4000rpm, blowing to near dryness by using soft nitrogen, fixing the volume to 0.5ml by using methanol, and entering an LC/MS/MS to be tested.
(3) Instrumental analysis
(3.1) conditions for liquid chromatography
Chromatographic column: produced by sameimer, usa (Thermo Scientific), model number Betasil C18 (100 mm x 2.1 mm), filler particle size 5 μm;
mobile phase: the phase A is methanol, the phase B is pure water, and the total flow rate of the phase A and the phase B is 0.3ml/min;
sample injection amount of automatic sample injector: 5 μl;
column oven temperature: 40 ℃;
the elution mode of the target compound is gradient elution, the total duration is 15min, and the elution program is as follows: 0-2min, and the proportion of phase B is 0-15%;2-3min, wherein the proportion of phase B is 15% -60%;3-5min, the proportion of phase B is 60% -70%;5-6.5min, and the proportion of the phase B is 70% -80%;6.5 to 7.5 minutes, and the proportion of the phase B is 80 to 90 percent; 7.5 to 8.5min, and the proportion of the phase B is 90 to 99 percent; 8.5-10min, the proportion of B is kept to be 99%;10-10.5min, wherein the proportion of the phase B is 99% -15%;10.5-15, the proportion of the phase B is kept to be 15%, and the process is finished.
(3.2) Mass Spectrometry-related parameters
Mass spectrometry scan mode: a multi-reaction monitor (Multiple Reaction Monitoring, MRM);
ionization mode: electrospray Ionization (ESI);
the detection mode is as follows: negative ion mode (Negative);
ion source Temperature (TEM): 550 ℃;
electrospray Voltage (IS): -4500V;
curtain Gas (CUR): 25.0Psi;
collision Gas (CAD): 7.0Psi;
atomizing Gas (Ion Source Gas 1): 35.0Psi;
auxiliary Gas (Ion Source Gas 2): 60Psi
The mass spectrum parameters of the target compounds are optimized in table 4.
Table 4 optimization of mass spectrometry parameters for target compounds
(4) The migration research method of bisphenol in the plastic snack box of the embodiment of the invention has the recovery rate
In this embodiment, the recovery rate of the internal standard and the recovery rate of the total sample matrix addition of all the test samples are shown in fig. 3, and the recovery rate of the internal standard is reduced by more than 55% compared with the previous method, but it can be seen that the same extractant is the same, and the extraction effect obtained when the internal standard is fused into the sample and the internal standard is attached to the surface is different, so that the detection rate of substances with low concentration in the environments of bisphenol B and bisphenol AF can be greatly improved, as shown in fig. 4 (B). The matrix marking recovery rate of the sample is 70% -110%, the standard deviation is 10% -20%, and the method is good in stability and high in accuracy.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (9)
1. A pretreatment method for monitoring the content or migration amount of endocrine disruptors in a plastic food packaging material is characterized by comprising heating, dissolving and remodelling;
the heating and dissolving means that: wiping off surface pollutants from a food packaging material to be measured, washing, drying, cutting into fragments or grinding, uniformly mixing, taking out a sample, putting the sample into a round glass culture dish, adding an internal standard mixed solution corresponding to the endocrine disrupter to be measured, covering a cover of the glass culture dish, standing to enable the internal standard to be fully and uniformly mixed on the surface of the sample, and then putting the sample into a muffle furnace to heat until the packaging material presents a molten state;
wherein the remodeling means: taking out the food packaging material in a molten state, naturally cooling the food packaging material at room temperature, and storing the food packaging material in a refrigerator so as to take out the sample for subsequent examination.
2. The pretreatment method for monitoring the content or migration of endocrine disruptors in plastic food packaging material according to claim 1, wherein:
the food packaging material is one of a plastic snack box, a plastic yoghurt packaging box and a plastic soda bottle.
3. The pretreatment method for monitoring the content or migration of endocrine disruptors in plastic food packaging material according to claim 1, wherein:
the internal standard in the internal standard mixed solution refers to deuterated or carbo-substituted products of the endocrine disruptors to be detected;
the food packaging material added into the round glass culture dish and the dosage of the internal standard mixed solution satisfy the following conditions: and placing 1-5g of each sample into a round glass culture dish, and correspondingly adding 50 mu L of internal standard mixed solution, wherein the concentration of an internal standard substance in the internal standard mixed solution is not lower than the concentration of a component to be detected and is not more than twice the concentration value of the component to be detected.
4. The pretreatment method for monitoring the content or migration of endocrine disruptors in plastic food packaging material according to claim 1, wherein:
the heating-induced packaging material is in a molten state, namely, the packaging material is heated for 5-15 minutes at 150-200 ℃.
5. Use of the pretreatment method according to any one of claims 1 to 4 for monitoring the content or migration of endocrine disruptors in plastic food packaging materials.
6. A method for monitoring the content of endocrine disruptors in a plastic food packaging material, comprising the steps of:
(1) Carrying out ultrasonic extraction on the food packaging material subjected to the pretreatment of claim 1;
(2) And detecting the extracted sample by a gas chromatography-mass spectrometer or a liquid chromatography-mass spectrometer.
7. The method of monitoring the content of endocrine disruptors in a plastic food packaging material according to claim 6, wherein:
the ultrasonic extraction in the step (1) refers to a three-time extraction process, wherein three-time ultrasonic extraction steps are as follows: taking out the cooled round slice, re-fragmenting the round slice, placing the round slice into a centrifuge tube, adding an extraction solvent 1, swirling, performing ultrasonic extraction, centrifuging in the centrifuge after swirling again to obtain a supernatant 1, adding an extraction solvent 2 into the centrifuge tube, swirling, performing ultrasonic extraction, centrifuging in the centrifuge after swirling again to obtain a supernatant 2, continuously adding an extraction solvent 3 into the centrifuge tube, swirling, performing ultrasonic extraction, centrifuging in the centrifuge after swirling again, collecting the supernatant 3, and combining the supernatant 1, the supernatant 2 and the supernatant 3; taking all supernatant fluid, passing through a 0.22 mu m nylon filter membrane, blowing nitrogen until the supernatant fluid is nearly dry, and fixing the volume to 0.5ml by using n-hexane or methanol to obtain a sample measured by the upper machine of the step (3);
the extraction solvent 1, the extraction solvent 2 and the extraction solvent 3 in the step (1) are independently selected from one or more of ethyl acetate, n-hexane, acetone and dichloromethane;
the gas chromatography conditions in the gas chromatography mass spectrometer described in the step (2) are as follows:
chromatographic column: model specification Rtx-5MS,30m*0.25mm I.D, 0.25 μm, available from America Anagalman;
carrier gas: high purity helium >99.999%;
sample injection mode: not split;
sample injection volume: 1 μl;
the sample inlet temperature is: 260 ℃;
chromatographic column temperature program: the initial temperature is 60 ℃, the temperature is kept for 2min, then the temperature is increased to 280 ℃ at the speed of 60 ℃/min, the temperature is kept for 2min, and then the temperature is increased to 290 ℃ at the speed of 10 ℃/min, and the temperature is kept for 12 min;
the mass spectrum conditions in the gas chromatography-mass spectrometer used in the step (2) are as follows:
chromatographic column interface and ion source temperature: 230 ℃ and 280 ℃;
solvent delay time: 3min
Detection voltage: 0.1kv relative to tuning results;
the conditions of liquid chromatography in the liquid chromatography mass spectrometer in the step (2) are as follows:
chromatographic column: model specification Betasil C18, 100mm x 2.1mm, filler particle size 5 μm from sameifer company, usa;
mobile phase: the phase A is methanol, the phase B is pure water, and the total flow rate of the phase A and the phase B is 0.3ml/min;
sample injection amount of automatic sample injector: 5 μl;
column oven temperature: 40 ℃;
the elution mode of the target compound is gradient elution, the total duration is 15min, and the elution program is as follows: 0-2min, and the proportion of phase B is 0-15%;2-3min, wherein the proportion of phase B is 15% -60%;3-5min, the proportion of phase B is 60% -70%;5-6.5min, and the proportion of the phase B is 70% -80%;6.5 to 7.5 minutes, and the proportion of the phase B is 80 to 90 percent; 7.5 to 8.5min, and the proportion of the phase B is 90 to 99 percent; 8.5-10min, the proportion of B is kept to be 99%;10-10.5min, wherein the proportion of the phase B is 99% -15%;10.5-15, keeping the proportion of the phase B to be 15%, and ending;
the relevant parameters of the mass spectrum in the liquid chromatography mass spectrometer in the step (2) are as follows:
mass spectrometry scan mode: a multi-reaction monitor;
ionization mode: electrospray ionization;
the detection mode is as follows: a negative ion mode;
ion source temperature: 550 ℃;
electrospray voltage: -4500V;
air curtain gas: 25.0Psi;
collision gas: 7.0Psi;
atomizing gas: 35.0Psi;
auxiliary gas: 60Psi.
8. A method of monitoring the migration of endocrine disruptors in a plastic food packaging material, comprising the steps of:
(1) Performing simulated soaking on the sample subjected to the pretreatment of claim 1;
(2) And detecting the simulated soaked gas chromatography-mass spectrometer or the liquid chromatography-mass spectrometer.
9. The method of monitoring the migration of endocrine disruptors in plastic food packaging material according to claim 8, wherein:
the simulated soaking in the step (1) means that the pretreated sample is soaked in acetic acid solution with the volume fraction of 4% for culture, 5ml of the sample is absorbed by a syringe in a screw test tube after the culture, 5ml of normal hexane or ethyl acetate solution is added, the mixture is uniformly mixed by vortex and then is subjected to ultrasonic treatment for 30min, the mixture is placed in a centrifugal machine for centrifugal treatment for 5min after vortex again, the speed is 4000rpm, supernatant is taken, gentle nitrogen is blown to near dryness, and the volume is fixed to 0.5ml by normal hexane or methanol to obtain the sample measured by the step (2);
the culturing in the step (1) refers to culturing at 25-75 ℃ for 1-10h;
the gas chromatography conditions in the gas chromatography mass spectrometer described in the step (2) are as follows:
chromatographic column: model specification Rtx-5MS,30m*0.25mm I.D, 0.25 μm, available from America Anagalman;
carrier gas: high purity helium >99.999%;
sample injection mode: not split;
sample injection volume: 1 μl;
the sample inlet temperature is: 260 ℃;
chromatographic column temperature program: the initial temperature is 60 ℃, the temperature is kept for 2min, then the temperature is increased to 280 ℃ at the speed of 60 ℃/min, the temperature is kept for 2min, and then the temperature is increased to 290 ℃ at the speed of 10 ℃/min, and the temperature is kept for 12 min;
the mass spectrum conditions in the gas chromatography-mass spectrometer used in the step (2) are as follows:
chromatographic column interface and ion source temperature: 230 ℃ and 280 ℃;
solvent delay time: 3min
Detection voltage: 0.1kv relative to tuning results;
the conditions of liquid chromatography in the liquid chromatography mass spectrometer in the step (2) are as follows:
chromatographic column: model specification Betasil C18, 100mm x 2.1mm, filler particle size 5 μm from sameifer company, usa;
mobile phase: the phase A is methanol, the phase B is pure water, and the total flow rate of the phase A and the phase B is 0.3ml/min;
sample injection amount of automatic sample injector: 5 μl;
column oven temperature: 40 ℃;
the elution mode of the target compound is gradient elution, the total duration is 15min, and the elution program is as follows: 0-2min, and the proportion of phase B is 0-15%;2-3min, wherein the proportion of phase B is 15% -60%;3-5min, the proportion of phase B is 60% -70%;5-6.5min, and the proportion of the phase B is 70% -80%;6.5 to 7.5 minutes, and the proportion of the phase B is 80 to 90 percent; 7.5 to 8.5min, and the proportion of the phase B is 90 to 99 percent; 8.5-10min, the proportion of B is kept to be 99%;10-10.5min, wherein the proportion of the phase B is 99% -15%;10.5-15, keeping the proportion of the phase B to be 15%, and ending;
the relevant parameters of the mass spectrum in the liquid chromatography mass spectrometer in the step (2) are as follows:
mass spectrometry scan mode: a multi-reaction monitor;
ionization mode: electrospray ionization;
the detection mode is as follows: a negative ion mode;
ion source temperature: 550 ℃;
electrospray voltage: -4500V;
air curtain gas: 25.0Psi;
collision gas: 7.0Psi;
atomizing gas: 35.0Psi;
auxiliary gas: 60Psi.
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