CN110988199B - A kind of determination method of 2-ethylhexyl acrylate in carbonated beverages - Google Patents

Abstract

The invention discloses a quantitative detection method of 2-ethylhexyl acrylate content in carbonated beverage, which mainly comprises the preparation of magnetic solid phase extraction material; preparing a standard working solution, a sample test solution and a blank test solution; gas chromatography-tandem triple quadrupole mass spectrometry; drawing a standard curve, calculating concentration and the like; the method has the advantages that the process is simple, the content of the 2-ethylhexyl acrylate in the carbonated beverage can be accurately measured by utilizing the sample pretreatment method and the conditions set by the chromatogram and the mass spectrum, the detection limit of the method is as low as 0.005mg/kg (5 mu g/kg), the method has good accuracy and reproducibility, and the method can be used for accurately, qualitatively and quantitatively determining.

Description

A kind of determination method of 2-ethylhexyl acrylate in carbonated beverages

technical field

The invention belongs to the technical field of compound content determination, in particular to a method for determining 2-ethylhexyl acrylate in carbonated beverages.

Background technique

Polyacrylate is a kind of high molecular polymer with excellent heat resistance, water resistance and oxidation resistance, so it is widely used in coatings, adhesives, leather, chemical fiber, synthetic plastics, paper industry and food contact materials. . Copolymers based on 2-ethylhexyl acrylate (2-ethylhexyl acrylate) have gradually become the most popular acrylate coatings due to their excellent color retention properties and physical processing properties. With the rapid development of China's packaging material industry, adhesives based on 2-ethylhexyl acrylate are more and more frequently used in the beverage industry.

In the production process, in order to improve the appearance and physical properties, beverage containers such as beverage bottles and beverage cans are processed with an adhesive with 2-ethylhexyl acrylate as the monomer. However, relevant studies have shown that 2-ethylhexyl acrylate has certain mutagenicity and genotoxicity. Such substances will migrate in the process of contacting food, especially from packaging materials and coatings to various Among the beverages, it will endanger the life and health of consumers. my country's national standard GB 9685 stipulates that the specific migration limit of 2-ethylhexyl acrylate in food contact materials is 0.05mg/kg. The harmfulness of phthalate plasticizers has been well known to the public, so it has a high degree of attention. The relevant detection methods are also mature, the monitoring is relatively strict, and the purchase and use can be effectively controlled; however, for carbonated beverages A complete and high-precision detection system has not yet been established for 2-ethylhexyl acrylate. Some unscrupulous merchants take advantage of this loophole and use 2-ethylhexyl acrylate instead of 2-ethyl phthalate. Hexyl ester (DEHP) is used to produce related food contact products. If it cannot be effectively supervised in time, it will easily cause greater food safety risks.

At present, there is no report on the detection of 2-ethylhexyl acrylate in carbonated beverages at home and abroad. Therefore, a simple, easy-to-operate and high-accuracy detection method for 2-ethylhexyl acrylate in carbonated beverage foods has been established, so as to carry out effective inspection and supervision on the product quality of carbonated beverage products, which will protect consumers' interests. Health and safety are important.

Chromatography-mass spectrometry is a common method for compound detection, but the detected substances are easily interfered by the matrix and affect the determination results. Therefore, the selection of chromatographic and mass spectrometry parameters is very important. Each compound corresponds to a different chromatogram. For mass spectrometry analysis conditions, only the correct chromatographic and mass spectrometry parameters can be selected to accurately analyze the target. If the parameter settings are not good, not only will you not be able to get satisfactory results, but it will even be interfered by false positive substances, resulting in wrong conclusions and affecting the accuracy of the analysis results; Although it has good sensitivity, it is not very suitable for the detection of target substances in aqueous food because the mass spectrometer needs to maintain a vacuum environment.

Therefore, the establishment of a sample pretreatment method that can rapidly enrich the target and remove the aqueous matrix is of great social significance and practicality for the rapid detection of the target 2-ethylhexyl acrylate in carbonated beverages. value.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the deficiencies in the prior art, and to provide a quantitative detection method for the content of 2-ethylhexyl acrylate in carbonated beverages, which has the advantages of simple measurement process, high result accuracy and good reproducibility.

The technical scheme of the present invention is: a quantitative detection method for the content of 2-ethylhexyl acrylate in carbonated beverages, which specifically includes the following steps:

(1) Preparation of magnetic solid phase extraction material: iron trichloride hexahydrate was dissolved in ethylene glycol at room temperature, after adding anhydrous sodium acetate and polyethylene glycol 600, adding sodium carbon nitride material, Stir to make it evenly suspended in the iron solution, and put the suspension into a high-pressure reactor for hydrothermal reaction. After the reaction is completed, the formed Fe ₃ O ₄ @C ₃ N ₄ magnetic solid phase material is collected with a magnet, and the reaction solution is poured out. , the magnetic solid phase material is washed with distilled water for use;

(2) Preparation of standard working solution, sample test solution and blank test solution:

① Preparation of standard working solution:

a. Prepare standard stock solution of 2-ethylhexyl acrylate: Accurately weigh 10 mg of 2-ethylhexyl acrylate standard with a content of more than 99.0% into a 100 mL volumetric flask, accurate to 0.1 mg, and use pesticide residue grade Dissolved in n-hexane and fixed to volume, sealed and stored at 4°C away from light;

b. Prepare standard solution of 2-ethylhexyl acrylate: Pipette 50 μL, 100 μL, 200 μL, 500 μL and 1000 μL of standard stock solution of 2-ethylhexyl acrylate into five 100 mL volumetric flasks, respectively, and use pesticide residues Grade n-hexane to constant volume, prepare standard working solutions with concentrations of 50μg/L, 100μg/L, 200μg/L, 500μg/L and 1000μg/L to be tested;

② Preparation of sample test solution:

Weigh 20-30g of carbonated beverage samples into a 50mL glass centrifuge tube, add 50-100mg of magnetic solid phase extraction material Fe ₃ O ₄ @C ₃ N ₄ , vortex for 2-5min, and centrifuge the glass with a magnet Absorb the Fe ₃ O ₄ @C ₃ N ₄ material on the outside of the tube, and pour out the carbonated beverage solution; add 2.0-3.0 mL of n-hexane solvent to the centrifuge tube, vortex for 5-15 s, and then extract by ultrasonic for 5-10 min; Absorb the magnetic solid phase material outside the centrifuge tube, take 1-2 mL of the supernatant, pass it through a 0.45 μm organic filter membrane, and place it in a sample injection vial for testing;

③ Preparation of blank test solution: replace the carbonated beverage used in ② with ultrapure water of the same quality, and other operations are consistent with ②;

(3) gas chromatography-tandem triple quadrupole mass spectrometry was used to measure the three solutions prepared in step 2 by gas chromatography-tandem triple quadrupole mass spectrometry; 2-ethylhexyl acrylate in the standard working solution The concentration x is the abscissa, and the corresponding measured product ion peak area y is the ordinate, draw the regression curve of the standard working solution, and calculate the slope a and intercept of the regression curve according to the linear equation y=ax+b obtained from the curve. distance b;

Among them, the settings of the measurement parameters of the gas chromatography-tandem triple quadrupole mass spectrometer detection instrument are as follows:

Gas chromatography conditions:

①Capillary chromatographic column: the length of the chromatographic column is 30～60m; the inner diameter of the chromatographic column is 0.25～0.50mm; the thickness of the coating film of the chromatographic column is 0.25～0.4μm;

②Programmed heating conditions: the initial temperature is 30-90°C, maintained for 2-6min, then heated to 200-325°C at a rate of 20-40°C/min, and maintained for 1-10min;

③ Sample injection volume: 1.0-5.0μL;

④The flow rate of carrier gas: 0.5～2.0mL/min;

Tandem triple quadrupole mass spectrometry conditions:

①Ion source: electron bombardment ion source (EI) or atmospheric pressure chemical ionization source (CI);

② Electron energy: 60-75eV;

③Ion source temperature: 150-250℃;

④ Detection method: Selected Ion Scanning (SIM) or Multiple Ion Reaction Detection (MRM);

⑤ Solvent delay: 2-8min;

⑥Carrier gas: Helium with a purity of 99.999%;

⑦Sheath air flow: 6～9L/min;

⑧ Collision gas: nitrogen with a purity of 99% to 99.995%;

⑨ Resolution: narrow or wide;

(4) Calculate the concentration c of the sample test solution and the concentration c ₀ of the blank test solution according to the formula c=[yb]/a, where the value of y corresponds to the quantitative ion of 2-ethylhexyl acrylate in the measured carbonated beverage sample or blank Peak area;

(5) The content of 2-ethylhexyl acrylate in carbonated beverages is X=(cc ₀ )/10, where X is the content of 2-ethylhexyl acrylate in carbonated beverages, in μg/kg; c is the concentration of the carbonated beverage sample test solution, c ₀ is the concentration of the blank test solution, and the unit is μg/L.

In step 1, the concentration range of ferric chloride in the ethylene glycol solution is 0.1-2.0 mol/L.

In step 1, the molar ratio of anhydrous sodium acetate to ferric chloride is 2-10:1.

In step 1, the molar ratio of polyethylene glycol 600 to ferric chloride is 0.01-0.5:1.

In step 1, the mass ratio of gC ₃ N ₄ to ferric chloride is 0.1-0.5:1.

In step 1, the temperature of the hydrothermal reaction is 150-250° C., and the reaction time is 5-24 h.

The beneficial effects of the present invention are:

The invention establishes a method for detecting the content of 2-ethylhexyl acrylate in carbonated beverages for the first time. The sample test solution can be directly injected into the test solution after being enriched by a magnetic solid phase material, separated from an aqueous phase, extracted with n-hexane and filtered by a filter membrane. No complicated pretreatment steps are required, and the target to be tested can be enriched efficiently, reducing the detection limit of the method; in addition, using the chromatographic and mass spectrometry setting conditions disclosed in this method, acrylic acid-2 in carbonated beverages can be accurately measured. -Ethylhexyl ester content, the detection limit of the method is as low as 0.005mg/kg, the method has good accuracy and reproducibility, and can be accurately qualitative and quantitative.

Description of drawings

Fig. 1 is the collision energy of 2-ethylhexyl acrylate;

Fig. 2 is acrylate-2-ethylhexyl acrylate content addition recovery rate and precision statistics;

Fig. 3 is a typical chromatogram of 2-ethylhexyl acrylate;

Figure 4 is a curve-type MRM mass spectrum of 2-ethylhexyl acrylate.

Detailed ways

The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Modifications and substitutions made to the methods, steps or conditions of the present invention without departing from the essence of the present invention all belong to the scope of the present invention.

Embodiment 1. The detection method of 2-ethylhexyl acrylate content in carbonated beverages

1. Preparation of magnetic solid phase extraction material: 2.7g FeCl ₃ ·6H ₂ O (10mmol) was dissolved in 50mL ethylene glycol, then 4.1g sodium acetate (50mmol) and 1.2g polyethylene glycol 600 (0.2mmol) were added. ), stir and dissolve; then add carbon nitride nanomaterials (gC ₃ N ₄ , which can be obtained by calcining urea or melamine at high temperature, and there are mature methods for preparation, see literature: Nat.Mater., 2009, 8,76-80; Angew.Chem.Int.Ed., 2012,51,68), stir to make it evenly suspended in the iron solution, and put the suspension into the autoclave (with a polytetrafluoroethylene tank), After the reaction kettle was tightened, the hydrothermal reaction was carried out at 220° C. for 15 h. After the reaction was over, the Fe ₃ O ₄ @C ₃ N ₄ material formed was collected with a magnet, and rinsed with distilled water for use.

2. Prepare standard working solution, sample test solution and blank test solution:

① Preparation of standard working solution:

a. Prepare standard stock solution of 2-ethylhexyl acrylate: Accurately weigh 10 mg of 2-ethylhexyl acrylate standard with a content of more than 99.0% into a 100 mL volumetric flask, accurate to 0.1 mg, and use pesticide residue grade The n-hexane was dissolved and made up to volume. The stock solution was sealed and stored at 4°C and protected from light. The content of 2-ethylhexyl acrylate in the solution was 100 mg/L;

b. Prepare standard solution of 2-ethylhexyl acrylate: Pipette 50 μL, 100 μL, 200 μL, 500 μL and 1000 μL of standard stock solution of 2-ethylhexyl acrylate into five 100 mL volumetric flasks, respectively, and use pesticide residues The standard working solution with the concentration of 50μg/L, 100μg/L, 200μg/L, 500μg/L and 1000μg/L is prepared to be tested;

② Preparation of sample test solution:

Weigh 20g of carbonated beverage samples into a 50mL glass centrifuge tube, add 100mg of magnetic solid phase extraction material Fe ₃ O ₄ @C ₃ N ₄ , vortex for 5 minutes, and use a magnet to absorb Fe ₃ outside the glass centrifuge tube O ₄ @C ₃ N ₄ material, pour off the carbonated beverage solution; add 2.0 mL of n-hexane solvent to the centrifuge tube, vortex for 10 s, and extract ultrasonically for 5 min; place a magnet outside the glass centrifuge tube to absorb the magnetic solid phase material , take 1 mL of the supernatant, pass it through a 0.45 μm organic filter membrane, and place it in a sample injection vial for testing;

③ Preparation of blank test solution: replace 20 g of carbonated beverage used in ② with 20 g of ultrapure water, and other operations are the same as in ②;

3. Use gas chromatography-tandem triple quadrupole mass spectrometer to perform gas chromatography-tandem triple quadrupole mass spectrometry respectively on the three solutions prepared in step 2; The concentration x is the abscissa, the corresponding measured product ion peak area y is the ordinate, and the regression curve of the standard working solution is drawn. According to the linear equation y=ax+b obtained from the curve, the slope a and intercept of the regression curve are calculated. b;

The instrument conditions for this measurement are set as follows:

Gas chromatography conditions:

1) Capillary chromatographic column: coating material, polymethylsiloxane coating; the length of the chromatographic column is 30m; the inner diameter of the chromatographic column is 0.25mm; the thickness of the chromatographic column coating is 0.25μm;

2) Program temperature conditions: the initial temperature is 50°C, maintained for 3 minutes, and the temperature is increased to 250°C at a rate of 20°C/min, and maintained for 5 minutes;

3) Sample injection volume: 1.0 μL;

4) Carrier gas flow rate: 1.0 mL/min.

Tandem triple quadrupole mass spectrometry conditions:

1) Ion source: electron bombardment (EI) ion source;

2) Electron energy: 70eV;

3) Ion source temperature: 230℃;

4) Detection method: Multiple ion reaction detection (MRM);

5) Solvent delay: 4.5min;

6) Carrier gas: helium with a purity of 99.999%;

7) Sheath air flow: 6L/min;

8) Collision gas: nitrogen with a purity of 99.995%;

9) Resolution: narrow peak width;

The collision energy is shown in Figure 1. In this example, the first-order spectrum analysis of acrylic acid-2-ethylhexyl ester was carried out under the electron bombardment ion source, and the first-order cracking peak of acrylic acid-2-ethylhexyl ester was obtained, and then collision-induced cracking ( CID), analyze the mass spectrometry fragments, under the optimized MS conditions, combined with the interference of acrylate homologues, select 112--->55 and 112--->41 as monitoring ions, of which 112 --->55 is a quantitative ion, and the collision energy of 112--->55 is 20eV; 112--->41 is a qualitative ion, and the collision energy of 112--->41 is 30eV.

4. According to the formula c=(yb)/a, calculate the concentration c of 2-ethylhexyl acrylate and the blank concentration c ₀ in the sample test solution; wherein y is the quantitative ion of 2-ethylhexyl acrylate in the test solution Peak area.

5. The content of acrylic acid-2-ethylhexyl in the carbonated beverage is X=(cc ₀ )/10, wherein X is the content of acrylic acid-2-ethylhexyl in the carbonated beverage, the unit is μg/kg; c is Carbonated beverage sample concentration, c ₀ is the blank concentration, and the unit is μg/L.

For the repeatability test, the food simulant test solution is prepared in parallel, and then steps 3 and 4 are performed. If the absolute difference between the two independent test results does not exceed 20% of the arithmetic mean, the test is accurate.

Embodiment two, adopt the addition method to detect the precision and the recovery rate of this method

Using the method of adding recovery rate, the samples of carbonated beverages without 2-ethylhexyl acrylate were added to the levels of 5.0 μg/kg, 50 μg/kg and 1000 μg/kg, respectively. Processing and determination, each level was measured 8 times in parallel, and the recovery rate and precision were calculated. The results of the recovery rate and precision test are shown in Figure 2.

It can be seen from Figure 2 that the recovery and precision of this method are good. The recovery rate of the method for the determination of various simulants is 85%-115%; the precision is below 10%, the quantification is accurate and reliable, and the reproducibility is good.

The method described in the present invention includes the selection and setting of experimental conditions only for the determination of the content of 2-ethylhexyl acrylate in carbonated beverages. Since the detection limit of this detection method can reach 0.005mg/kg (5μg/kg), which is far less than the standard limit of 0.05mg/kg, it can effectively detect 2-ethylhexyl acrylate in carbonated beverage products. Inspection and supervision.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. However, the above descriptions are only specific embodiments of the present invention, and the technical features of the present invention are not limited thereto. within the scope of the invention patent.

Claims (6)

1. A quantitative determination method for the content of 2-ethylhexyl acrylate in carbonated beverages is characterized by comprising the following specific steps:

(1) preparing a magnetic solid phase extraction material: dissolving ferric trichloride hexahydrate in ethylene glycol at room temperature, adding anhydrous sodium acetate and polyethylene glycol 600, adding a carbon nitride nano material, stirring to enable the carbon nitride nano material to be uniformly suspended in an iron solution, putting the suspension into a high-pressure reaction kettle for hydrothermal reaction, and collecting formed Fe by using a magnet after the reaction is finished ₃O₄@C₃N₄Pouring out the reaction liquid from the magnetic solid-phase material, and washing the magnetic solid-phase material with distilled water for later use;

(2) preparing a standard working solution, a sample test solution and a blank test solution:

preparation of standard working solution:

a. preparation of 2-ethylhexyl acrylate standard stock solutions: accurately weighing 10mg of acrylic acid-2-ethylhexyl ester standard substance with the content of more than 99.0% into a 100mL volumetric flask, accurately measuring the content to 0.1mg, dissolving the standard substance by using n-hexane with pesticide residue level, fixing the volume, and sealing and storing the standard substance at 4 ℃ in a dark place;

b. preparation of 2-ethylhexyl acrylate standard use solutions: respectively transferring 50 mu L, 100 mu L, 200 mu L, 500 mu L and 1000 mu L of 2-ethylhexyl acrylate standard stock solution into 5 100mL volumetric flasks, using pesticide residue grade n-hexane for constant volume, and preparing standard working solutions with the concentrations of 50 mu g/L, 100 mu g/L, 200 mu g/L, 500 mu g/L and 1000 mu g/L to be tested;

preparing a sample test solution:

weighing 20-30g carbonated beverage sample to 50mL glassAdding 50-100mg of magnetic solid phase extraction material Fe into a glass centrifuge tube₃O₄@C₃N₄After vortex oscillation for 2-5min, using magnet to attract Fe outside the glass centrifuge tube₃O₄@C₃N₄Material, pouring off the carbonated beverage solution; adding 2.0-3.0mL of n-hexane solvent into a glass centrifuge tube, performing vortex oscillation for 5-15s, and performing ultrasonic extraction for 5-10 min; placing a magnet outside a centrifuge tube to absorb the magnetic solid phase material, taking 1-2mL of supernatant, filtering the supernatant through a 0.45-micrometer organic filter membrane, and placing the supernatant in a sample injection vial to be tested;

Preparing a blank test solution: replacing the carbonated beverage used in the second step with ultrapure water with equal quality, and keeping the other operations consistent with the second step;

(3) respectively carrying out gas chromatography-tandem triple quadrupole mass spectrometry on the three solutions prepared in the step 2 by adopting a gas chromatography-tandem triple quadrupole mass spectrometer; taking the concentration x of the 2-ethylhexyl acrylate in the standard working solution as an abscissa and the corresponding measured peak area y of the daughter ion as an ordinate, drawing a regression curve of the standard working solution, and calculating the slope a and the intercept b of the regression curve according to a linear equation y which is obtained by the curve and is ax + b;

the gas chromatography-tandem triple quadrupole mass spectrometer detection instrument measurement parameters are set as follows:

gas chromatography conditions:

capillary chromatographic column: coating material, polymethylsiloxane coating; the length of the chromatographic column is 30-60 m; the inner diameter of the chromatographic column is 0.25-0.50 mm; the thickness of the chromatographic column coating film is 0.25-0.4 mu m;

temperature programming conditions: the initial temperature is 30-90 ℃, the temperature is kept for 2-6min, the temperature is raised to 200 ℃ and 325 ℃ at the speed of 20-40 ℃/min, and the temperature is kept for 1-10 min;

sample introduction amount: 1.0-5.0 μ L;

carrier gas flow rate: 0.5-2.0 mL/min;

tandem triple quadrupole mass spectrometry conditions:

An ion source: electron bombardment ion sources or atmospheric pressure chemical ionization sources;

electron energy: 60-75 eV;

③ ion source temperature: 150 ℃ and 250 ℃;

and fourthly, a detection mode: selecting ion scanning or multi-ion reaction detection;

solvent delay: 2-8 min;

carrier gas: helium gas with a purity of 99.999%;

seventh, flow of sheath gas: 6-9L/min;

and collision gas: nitrogen with purity of 99-99.995%;

ninthly, resolution ratio: narrow or wide;

(4) according to the formula c ═ y-b]A, calculating the concentration c of the sample test solution and the concentration c of the blank test solution₀Wherein the y-value corresponds to the measured quantitative ion peak area of 2-ethylhexyl acrylate in the carbonated beverage sample or blank;

(5) the content of 2-ethylhexyl acrylate in the carbonated beverage is X ═ c-c₀) (10), wherein X is the content of 2-ethylhexyl acrylate in the carbonated beverage in μ g/kg; c is the concentration of the carbonated beverage sample test solution, c₀The concentration of the blank test solution is expressed in the unit of mu g/L.

2. The method for quantitatively determining the content of 2-ethylhexyl acrylate in a carbonated beverage as claimed in claim 1, wherein in step 1, the concentration of ferric chloride in the ethylene glycol solution is in the range of 0.1 to 2.0 mol/L.

3. The method for quantitatively detecting the content of 2-ethylhexyl acrylate in a carbonated beverage as claimed in claim 1, wherein in step 1, the molar ratio of anhydrous sodium acetate to ferric chloride is 2-10: 1.

4. The method for quantitatively detecting the content of 2-ethylhexyl acrylate in a carbonated beverage as claimed in claim 1, wherein in step 1, the molar ratio of polyethylene glycol 600 to ferric chloride is 0.01 to 0.5: 1.

5. the method for quantitatively determining the content of 2-ethylhexyl acrylate in a carbonated beverage as claimed in claim 1, wherein in step 1，g-C₃N₄The mass ratio of the ferric trichloride to the ferric trichloride is 0.1-0.5: 1.

6. the method for quantitatively detecting the content of 2-ethylhexyl acrylate in carbonated beverage as claimed in claim 1, wherein the hydrothermal reaction is carried out at 150 ℃ and 250 ℃ for 5-24h in step 1.

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