CN116026976A - Method for determining phthalate in water-based adhesive - Google Patents

Abstract

The invention belongs to the technical field of physical and chemical inspection, and particularly relates to a method for measuring phthalate compounds in water-based adhesive, which comprises the following steps: (1) After weighing the sample, dispersing ultrapure water, adding n-hexane, spherical carbon and an internal standard for oscillation extraction, centrifuging and filtering to obtain a sample solution to be detected; (2) Carrying out determination analysis on a sample solution to be detected by using supercritical fluid chromatography-tandem mass spectrometry; the chromatographic column of the supercritical fluid chromatography in the supercritical fluid chromatography-tandem mass spectrometry is Viriddis HSS C18SB. The spherical carbon can play a good role in adsorbing and purifying non-target objects in the water-based adhesive, and the supercritical fluid chromatography-tandem mass spectrometry analysis of phthalate esters in the water-based adhesive greatly shortens the chromatographic separation time, has good separation effect, and is low in organic solvent consumption and environment-friendly.

Description

Method for determining phthalate in water-based adhesive

Technical Field

The invention belongs to the technical field of physical and chemical inspection, and particularly relates to a method for measuring phthalate in water-based adhesive.

Background

As a plasticizer with wide application, phthalate plays a role similar to female hormone in human and animal bodies, can interfere endocrine, and limits the application range and the application amount of the phthalate in various countries in the world. Currently, methods for detecting phthalate plasticizers mainly include gas chromatography, gas chromatography-mass spectrometry, liquid chromatography, and liquid chromatography-mass spectrometry. The method comprises the steps of measuring phthalate compounds in water-based adhesives for cigarettes by using an ultra-high performance liquid chromatography-tandem mass spectrometry (Yan and the like, analytical test school report, 2015, 34 (2): 134-140), and measuring phthalate esters in water-based latexes for cigarettes by using a gas chromatography/mass spectrometry (Yang and the like, tobacco science and technology, 2011, 7:48-51).

While the prior art achieves effective detection of phthalate esters, these methods mainly face the following problems in the actual detection process: firstly, the detection time is relatively long, and in order to effectively separate various phthalic acid esters, different temperature gradients or elution gradients are required to ensure that all target substances are completely separated, even the separation degree difference between isomers; secondly, the detection cost is relatively high, a large amount of toxic and harmful solvents are required to be consumed, and the method is not environment-friendly. Li Wulin et al also used ultra-high performance co-phase chromatography to rapidly detect 15 phthalates in plastic products (chromatograph, 2016, 34 (8): 795-800), but the method was not compatible with water-based gel matrices and had low sensitivity, ignoring the effects of matrix effects in the assay.

Disclosure of Invention

Therefore, the technical problems to be solved by the invention are to overcome the defects of long detection time and high detection cost in the prior art, thereby providing the method for determining the phthalate in the water-based adhesive, which has the advantages of high separation speed, low solvent consumption and good quantitative effect.

For this purpose, the invention provides a method for determining phthalate esters in water-based adhesives, which comprises the following steps:

(1) Weighing a sample, adding water to disperse, adding an isotope mixed internal standard solution, extracting n-hexane and spherical carbon, and centrifuging and filtering to obtain a sample solution to be detected;

(2) Performing determination analysis on the sample solution to be detected by using a supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS); the chromatographic column of the supercritical fluid chromatography in the supercritical fluid chromatography-tandem mass spectrometry is Viriddis HSS C18SB.

The water-based adhesive refers to an adhesive made of a film-forming material which can be dispersed or dissolved in water, also called a water-soluble adhesive, and the phthalates detected by the invention are diphenyl phthalate (DPHP), butyl Benzyl Phthalate (BBP), di (2-methoxy) ethyl phthalate (DMEP) and di (2-ethoxy) ethyl phthalate (DEEP).

Further, the chromatographic column measurement conditions were: the mobile phase A is supercritical CO2, and the mobile phase B is one or more of methanol, ethanol and isopropanol; the total flow rate of the two phases after mixing is 0.7-1.0mL/min; the column temperature is 45-50 ℃; the sample injection amount is 2-3 mu L, and the elution mode is gradient elution.

Further, the volume ratio of the mobile phase A in the gradient elution is reduced from 95-99% to 85-89% in 0-3.5min, and then is recovered to 95-99% in 3.5-6 min.

Further preferably, the gradient elution is carried out for 0-1min, and the volume ratio of the mobile phase A is 98-99%; the volume ratio of the mobile phase A is reduced from 98-99% to 95-96% in 1-2.5 min; the volume ratio of the mobile phase A is reduced from 95-96% to 88-90% within 2.5-3.2 min; the volume ratio of the mobile phase A is kept 88-90% within 3.2-4.0 min; the volume ratio of the mobile phase A is increased from 88 to 90 percent to 98 to 99 percent within 4.0 to 4.5 minutes; the volume ratio of the mobile phase A is kept 98-99% within 4.5-6.0 min.

Further, the determination conditions of the mass spectrum in the supercritical fluid chromatography-tandem mass spectrum are as follows: the scanning mode is positive ion scanning; adopting MRM mode collection; electrospray ion source with ion source temperature of 140-160 ℃; the capillary voltage is 2.6-3.0kV; the air flow of the taper hole is 60-80L/h; the flow rate of the desolventizing agent is 600-800L/h; the temperature of the desolventizing gas is 300-350 ℃;

further preferably, the ion source temperature is 140-150 ℃; the capillary voltage is 2.6-2.8kV; the air flow of the taper hole is 70-80L/h; the flow rate of the desolventizing agent is 650-700L/h; the desolventizing gas temperature is 310-330 ℃.

Further, the preparation steps of the isotope mixing internal standard solution are as follows: respectively dissolving standard substances of corresponding internal standards of various phthalic acid esters with n-hexane, and then fixing the volume to obtain standard stock solutions of the corresponding internal standards of various phthalic acid esters; and respectively taking standard stock solutions of corresponding internal standards of various phthalic acid esters, mixing, and then, fixing the volume by using n-hexane to obtain an isotope mixed internal standard solution.

Further, the ratio of the amount of the sample to the amount of n-hexane is 0.18 to 0.22g:7-12mL.

Further, the mass ratio of the spherical carbon to the sample is 4-6:0.01-0.03.

Further, the extraction is oscillation extraction with the speed of 200-250r/min and the time of 8-12min.

The technical scheme of the invention has the following advantages:

1. according to the method for determining the phthalate in the water-based adhesive, the spherical carbon and the n-hexane are adopted to extract the water-based adhesive sample, and the method integrates the extraction and purification of the sample, so that the operation is simpler and faster. The spherical carbon can play a good role in adsorbing and purifying polar and nonpolar non-target objects in the water-based adhesive, so that the loss of components to be detected caused by the concentration and purification processes of the sample is avoided; and the phthalic acid ester in the water-based adhesive is determined by SFC-MS/MS analysis, and the chromatographic column is Viriddis HSS C18SB, so that the separation speed of detected target gift and impurity can be increased, the solvent consumption is low, and the quantitative effect is good.

2. In the method for determining phthalate in the water-based adhesive provided by the invention, the mobile phase A adopts supercritical CO ₂ The mobile phase B adopts one or more of methanol, ethanol and isopropanol; the total flow rate of the two phases after mixing is 0.7-1.0mL/min; the column temperature is 45-50 ℃; the sample injection amount is 2-3 mu L, the elution mode is gradient elution, and the method has the advantages of high separation speed and strong specificity, and by optimizing the detection conditions of the instrument, the chromatographic separation time is greatly shortened, and the separation degree is good (baseline separation).

3. In the method for determining phthalic acid ester in the water-based adhesive, the volume ratio of the SFC-MS/MS chromatographic column in the mobile phase A is reduced from 95-99% to 85-89% in 0-3.5min by chromatographic test conditions and gradient elution, and then the solution is recovered to 95-99% in 3.5-6min by gradient elution, so that effective separation of components to be tested is realized, and the accuracy of a test result is improved.

4. According to the method for determining the phthalate in the water-based adhesive, provided by the invention, the components to be tested of the water-based adhesive sample can be effectively extracted by adjusting the dosages of the n-hexane and the spherical carbon within a proper range, the use of an organic solvent is reduced, the cost is reduced, and the pollution to the environment is reduced. The particle size of the spherical carbon is selected to be in the range of 0.5-1 mu m, so that the spherical carbon can be ensured to have larger surface area, the effective adsorption of non-target substances is realized, the separation is realized, and the extraction time of a sample solution to be detected is shortened. The proper oscillation rate and extraction time can improve the extraction effect of the spherical carbon on the components to be detected and save time and cost.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of an assay method of the present invention;

FIG. 2 is a chromatogram of the sample to be tested having phthalate added in example 1 in an amount of 5.0. Mu.g/g;

FIG. 3 is a chromatogram of the sample to be tested having phthalate added in comparative example 1 in an amount of 5.0. Mu.g/g.

Detailed Description

The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.

The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge. All the standard products are purchased from Shanghai Annotation experiment technology limited company, and the purity is more than 99.5%; multiwall carbon nanotubes, available from Shanghai Annotation science and technology Co.

Example 1

The embodiment provides a specific method and a flow chart for determining phthalate in water-based adhesive, which are shown in figure 1, and specifically comprise the following steps:

(1) Weighing 0.2g of water-based adhesive, putting the water-based adhesive into a 20mL glass triangular flask, adding 2mL of ultrapure water for dispersion, sequentially adding 100uL of isotope mixed internal standard solution, 8mL of normal hexane and 50mg of spherical carbon, and carrying out oscillation extraction for 10min (the speed is 200 r/min) to obtain an extracting solution; and then taking supernatant, centrifuging and filtering to obtain a sample solution to be detected.

(2) The preparation method of the isotope mixed internal standard solution comprises the following steps: respectively weighing 10mg (accurate to 0.1 mg) of standard substances (namely DPHP, BBP, DEEP, DMEP) of corresponding internal standards of each phthalate in a 10mL volumetric flask, dissolving with n-hexane, and fixing the volume to scale to obtain standard stock solution of the corresponding internal standards of each phthalate; and respectively transferring 1mL of standard stock solution of the corresponding internal standard of each phthalate into a same 100mL volumetric flask, and fixing the volume to the scale by using normal hexane to obtain 10 mug/mL isotope mixed internal standard solution, and storing the isotope mixed internal standard solution at the temperature of minus 18 ℃ in a dark place.

(3) Preparation of mixed standard working solution: 1mL of a mixed solution of phthalate with the concentration of 100 mug/mL (namely DPHP, BBP, DEEP, DMEP with the concentration of 100 mug/mL) is removed to a 10mL volumetric flask, and diluted with normal hexane to fix the volume to prepare a mixed standard stock solution with the concentration of 10 mug/mL; respectively transferring 0.02mL, 0.05mL, 0.1mL, 0.2mL, 0.5mL and 1mL of mixed standard stock solution into a 10mL volumetric flask, adding 100uL isotope mixed internal standard solution, and fixing the volume by using normal hexane to prepare mixed standard working solutions with different concentrations, wherein the concentration sequences are as follows: 20. 50, 100, 200, 500, 1000ng/mL;

(4) Standard curve acquisition: and (3) injecting the prepared mixed standard working solutions with different concentrations into SFC-MS/MS, and quantitatively analyzing phthalate esters by an internal standard method, namely, performing linear regression analysis on the peak areas of all the standard samples, the corresponding internal standard peak area ratio (y) and the concentration (x) of the standard samples to obtain standard curves.

(5) Analysis of the sample solution to be tested: and (3) injecting the sample solution to be detected obtained in the step (1) into SFC-MS/MS, measuring, and substituting the chromatographic peak area ratio of the phthalate and the internal standard into a standard curve to obtain the phthalate content in the sample.

The chromatographic conditions used in the measurement are: the chromatographic column is Viridis HSS C18SB (3 mm. Times.100 mm,1.8 μm, waters, USA); mobile phase A is supercritical CO ₂ Mobile phase B is ethanol; the flow rate after mixing the two phases is 0.7mL/min; the column temperature is 45 ℃; the sample injection amount is 2 mu L; the elution mode is gradient elution, the gradient elution program is as follows,

time (min)	Mobile phase a (%)	Mobile phase B (%)
			0	99	1.0
1.0	99	1.0
			2.5	96	4.0
3.2	90	10
			4.0	90	10
4.5	99	1.0
			5.5	99	1.0

The mass spectrum conditions adopted in the measurement are as follows: the scanning mode is positive ion scanning; an electrospray ion source; the ion source temperature is 140 ℃; the capillary voltage is 2.6kV; the air flow of the taper hole is 70L/h; the flow rate of the desolventizing agent is 650L/h; the desolventizing gas temperature is 310 ℃; with MRM mode acquisition, the MRM parameters are shown in the table below,

* Quantification of ions

The chromatogram of the water-based adhesive sample measured by the method of example 1 is shown in fig. 2.

Example 2

This example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: in the extraction of the sample solution to be tested, 0.18g of the sample to be treated is extracted with 9mL of n-hexane, and the spherical carbon is 45mg.

Example 3

This example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: in the extraction of the sample solution to be tested, 0.22g of the sample to be treated is extracted by 11mL of n-hexane, and the spherical carbon is 55mg.

Example 4

This example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: the oscillation extraction rate was 250r/min.

Example 5

This example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: the total flow rate after mixing of the two phases was 1.0mL/min.

Example 6

This example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: when SFC-MS/MS is separated, the column temperature is 50 ℃; the sample loading was 3. Mu.L.

Example 7

This example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: the temperature of the ion source is 150 ℃; the capillary voltage is 2.8kV; the air flow of the taper hole is 80L/h; the flow rate of the desolventizing agent is 700L/h; the desolventizing gas temperature was 330 ℃.

Example 8

This example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: gradient elution procedure was different, see table below

Time (min)	Mobile phase a (%)	Mobile phase B (%)
			0	98	2.0
1.0	98	2.0
			2.5	95	5.0
3.2	88	12
			4.0	88	12
4.5	98	2.0
			5.5	98	2.0

Comparative example 1

The method for treating and detecting the sample solution to be detected in the comparative example is the same as that of the method for detecting phthalate compounds in water-based adhesives for cigarettes by using ultra-high performance liquid chromatography-tandem mass spectrometry (Yan, etc., analytical test report, 2015, 34 (2): 134-140). The recovery rate was 78.3-87.7%, and since the matrix effect was not considered, the recovery rate was significantly lower than that of the present invention.

Comparative example 2

The method for treating the sample solution to be tested in this comparative example was the same as in example 1, and the detection method was the same as in "gas chromatography/Mass Spectrometry Combined method for determining phthalate esters in Water-based emulsion for tobacco" (Yang et al, tobacco science and technology, 2011, 7:48-51). The method has long separation time and pretreatment time, and is not suitable for detecting a large amount of daily samples.

Comparative example 3

This comparative example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: the column used was a Viriddis BEH (2.1 mm. Times.100 mm,1.7 μm). The chromatogram is shown in FIG. 3, and the phthalate peak shape and the degree of separation are poor.

Comparative example 4

This comparative example provides a specific method for determining phthalate esters in water-based adhesives, which is substantially the same as example 1, except that: the spherical carbon of example 1 was replaced with multiwall carbon nanotubes having a particle size of 0.5 to 1 μm.

Experimental example 1

Recording the analysis time in the mass spectrometer as separation time for each example and comparative example; the time of the sample treatment stage is time consuming for pretreatment; recovery and average Relative Standard Deviation (RSD) of phthalate and organic solvents and amounts used are shown in the table below,

from the above table, comparative example 1 has a lower recovery rate, and a longer separation time, and consumes more toxic and harmful solvents than example 1. Comparative example 4 has lower recovery than example 1, indicating that spherical carbon has better purification effect on interfering substances in the water-based adhesive, less extract matrix, and more accurate result after internal standard correction. The pretreatment method can better remove impurities and reduce the interference to the detection result.

Experimental example 2

(1) Sensitivity detection

Different concentrations of labeled samples (0.05, 0.10, 0.2, 0.40 mg/kg) were prepared from blank aqueous gel samples, and after extraction and purification, were injected into SFC-MS/MS to produce a concentration of 3 times signal to noise ratio (S/n=3) as the method detection Limit (LOD) and a concentration of 10 times signal to noise ratio (S/n=3) as the method quantification Limit (LOQ). The detection limit of the phthalate (namely DPHP, BBP, DEEP, DMEP) is 0.05-0.09 mug/g respectively, and the quantitative limit is 0.25-0.30 mug/g respectively.

(2) Accuracy and repeatability

In example 1, linear regression analysis was performed on each phthalate standard peak area and its corresponding internal standard peak area ratio (y) and its concentration (x) to obtain a standard curve, see table below.

To judge the repeatability of the measurement method of the invention, 0.1mL of a mixed solution of phthalate with a concentration of 10. Mu.g/mL was added to 0.2g of a blank sample so that the phthalate content of the sample was 5.0mg/kg, thereby obtaining a sample to be measured. The labeled test samples were then measured as in example 1, and the experiment was repeated 5 times, and the recovery was calculated as scalar addition and measurement values, with the results shown in the following table,

as can be seen from the above table, the average recovery of phthalate is between 93.5% and 98.7% with an average Relative Standard Deviation (RSD) of less than 5.0%. The method has the advantages of high recovery rate, stable method and good repeatability.

The DMEP content of the 5.0mg/kg labeled sample measured by the detection method of example 1 and comparative example 2 was 4.97 mg/kg and 4.15mg/kg, respectively. The method has better accuracy, environmental protection, high efficiency and time saving.

The measurement results of the examples and the comparative examples show that the invention is economical, environment-friendly and high in efficiency. And aiming at the characteristics of the water-based adhesive, spherical carbon is selected as a purifying material, so that not only can the interfering substances in the matrix be well removed, but also a better recovery rate can be obtained. As can be seen from the measurement results of example 1 and comparative example, the pretreatment conditions used in the present invention are simple, the extraction and purification are integrated, and no organic solvent having high toxicity is used. The method has better accuracy after the isotope internal standard corrects the matrix effect.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims (10)

1. A method for determining phthalate esters in a water-based adhesive, comprising the steps of:

(1) Weighing a sample, adding water to disperse, adding an isotope mixed internal standard solution, extracting n-hexane and spherical carbon, and centrifuging and filtering to obtain a sample solution to be detected;

(2) Carrying out determination analysis on a sample solution to be detected by using a supercritical fluid chromatography-tandem mass spectrometry method; the chromatographic column of the supercritical fluid chromatography in the supercritical fluid chromatography-tandem mass spectrometry is Viriddis HSS C18SB.

2. The method for determining phthalate esters in water-based adhesives according to claim 1 wherein the chromatographic column determination conditions are: mobile phase A is supercritical CO ₂ The mobile phase B is one or more of methanol, ethanol and isopropanol; the total flow rate of the two phases after mixing is 0.7-1.0mL/min; the column temperature is 45-50 ℃; the sample injection amount is 2-3 mu L, and the elution mode is gradient elution.

3. The method for determining phthalic acid ester in water-based adhesive according to claim 2, wherein the volume ratio of mobile phase a is reduced from 95% -99% to 85% -89% in 0-3.5min, and is restored to 95% -99% in 3.5-6 min.

4. A method for determining phthalate esters in aqueous based adhesives according to claim 2 or 3 wherein said gradient elution is preferably carried out for 0-1min with a volume ratio of mobile phase a of 98-99%; the volume ratio of the mobile phase A is reduced from 98-99% to 95-96% in 1-2.5 min; the volume ratio of the mobile phase A is reduced from 95-96% to 88-90% within 2.5-3.2 min; the volume ratio of the mobile phase A is kept 88-90% within 3.2-4.0 min; the volume ratio of the mobile phase A is increased from 88 to 90 percent to 98 to 99 percent within 4.0 to 4.5 minutes; the volume ratio of the mobile phase A is kept 98-99% within 4.5-6.0 min.

5. The method for determining phthalate in aqueous based adhesives according to claim 1 wherein the determination conditions of mass spectrometry in supercritical fluid chromatography-tandem mass spectrometry are: the scanning mode is positive ion scanning; adopting MRM mode collection; electrospray ion source with ion source temperature of 140-160 ℃; the capillary voltage is 2.6-3.0kV; the air flow of the taper hole is 60-80L/h; the flow rate of the desolventizing agent is 600-800L/h; the desolventizing gas temperature is 300-350 ℃.

6. The method for determining phthalic acid esters in water-based glue according to claim 1 or 5, wherein the determination conditions of mass spectrum in the supercritical fluid chromatography-tandem mass spectrum are preferably: the temperature of the ion source is 140-150 ℃; the capillary voltage is 2.6-2.8kV; the air flow of the taper hole is 70-80L/h; the flow rate of the desolventizing agent is 650-700L/h; the desolventizing gas temperature is 310-330 ℃.

7. The method for determining phthalate esters in water-based adhesives according to claim 1 wherein: the preparation method of the isotope mixed internal standard solution comprises the following steps: respectively dissolving standard substances of corresponding internal standards of various phthalic acid esters with n-hexane, and then fixing the volume to obtain standard stock solutions of the corresponding internal standards of various phthalic acid esters; and respectively taking standard stock solutions of corresponding internal standards of various phthalic acid esters, mixing, and then, fixing the volume by using n-hexane to obtain an isotope mixed internal standard solution.

8. The method for determining phthalate esters in water-based adhesives according to any of claims 1 to 7 wherein the ratio of the amount of said sample to the amount of n-hexane is 0.18 to 0.22g:7-12mL.

9. The method for determining phthalate esters in water-based adhesives according to any of claims 1 to 8 wherein the ratio of spherical carbon to sample is 4 to 6 by mass: 0.01-0.03.

10. The method for determining phthalate in an aqueous based adhesive according to claim 1 wherein said extraction is an oscillatory extraction at a rate of 200-250r/min for a period of 8-12min.

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