A method for determining phthalates in water-based adhesives

Abstract

The present invention belongs to the field of physical and chemical testing technology, and specifically is a method for determining phthalate compounds in water-based adhesives. The method comprises the following steps: (1) weighing a sample, dispersing it in ultrapure water, adding n-hexane, spherical carbon, and an internal standard for oscillation extraction, centrifuging, and filtering to obtain a sample solution to be tested; (2) using supercritical fluid chromatography-tandem mass spectrometry to determine and analyze the sample solution to be tested; the supercritical fluid chromatography column in the supercritical fluid chromatography-tandem mass spectrometry is Viridis HSS C18SB. The spherical carbon can effectively adsorb and purify non-target substances in the water-based adhesive. The supercritical fluid chromatography-tandem mass spectrometry analysis of phthalates in the water-based adhesive greatly shortens the chromatographic separation time, achieves good separation effect, consumes less organic solvent, and is environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of physical and chemical testing, and particularly relates to a method for determining phthalates in water-based adhesives. Background Art

[0002] Phthalates, a widely used plasticizer, play a role similar to estrogen in humans and animals, disrupting endocrine function. Countries around the world have imposed restrictions on their scope of use and dosage. Currently, the main methods for detecting phthalate plasticizers include gas chromatography, gas chromatography-mass spectrometry, liquid chromatography, and liquid chromatography-mass spectrometry. For example, "Determination of Phthalates in Water-Based Glues for Tobacco Use by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry" (Yan Jin et al., Journal of Analysis and Testing, 2015, 34(2):134-140) and "Determination of Phthalates in Water-Based Latex for Tobacco Use by Gas Chromatography / Mass Spectrometry" (Yang Bin et al., Tobacco Science and Technology, 2011, 7:48-51).

[0003] Although existing technologies have achieved effective detection of phthalates, these methods face the following main problems in the actual detection process: first, the detection time is relatively long. In order to effectively separate multiple phthalates, different temperature gradients or elution gradients are required to ensure that each target is completely separated, and even the separation between isomers is poor; second, the detection cost is relatively high, requiring the consumption of a large amount of toxic and hazardous solvents, which is not environmentally friendly. Li Wulin et al. also used ultra-high performance convergence chromatography to quickly detect 15 phthalates in plastic products (Chromatography, 2016, 34(8):795-800), but this method is not suitable for water-based adhesive matrices, has low sensitivity, and ignores the influence of matrix effects in the determination. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art such as long detection time and high detection cost, thereby providing a method for determining phthalates in water-based adhesives with fast separation speed, low solvent consumption and good quantitative effect.

[0005] To this end, the present invention provides a method for determining phthalates in a water-based adhesive, comprising the following steps:

[0006] (1) Weigh the sample, disperse it in water, add isotope mixed internal standard solution, extract it with n-hexane and spherical carbon, and then centrifuge and filter to obtain the sample solution to be tested;

[0007] (2) The sample solution was measured and analyzed by 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 was Viridis HSS C18 SB.

[0008] Water-based adhesive refers to an adhesive made of a film-forming material that can be dispersed or dissolved in water, also known as a water-soluble adhesive. The phthalates detected in this invention include diphenyl phthalate (DPHP), butyl benzyl phthalate (BBP), di(2-methoxy)ethyl phthalate (DMEP) and di(2-ethoxy)ethyl phthalate (DEEP).

[0009] Furthermore, the chromatographic column measurement conditions are as follows: mobile phase A is supercritical CO2, mobile phase B is one or more of methanol, ethanol, and isopropanol; the total flow rate after the two phases are mixed is 0.7-1.0 mL / min; the column temperature is 45-50°C; the injection volume is 2-3 μL, and the elution method is gradient elution.

[0010] Furthermore, during the gradient elution, the volume ratio of the mobile phase A is reduced from 95%-99% to 85%-89% within 0-3.5 minutes, and then restored to 95%-99% within 3.5-6 minutes.

[0011] Further preferably, in the gradient elution, the volume proportion of mobile phase A is 98-99% at 0-1 min; at 1-2.5 min, the volume proportion of mobile phase A is reduced from 98-99% to 95-96%; at 2.5-3.2 min, the volume proportion of mobile phase A is reduced from 95-96% to 88-90%; at 3.2-4.0 min, the volume proportion of mobile phase A is maintained at 88-90%; at 4.0-4.5 min, the volume proportion of mobile phase A is increased from 88-90% to 98-99%; at 4.5-6.0 min, the volume proportion of mobile phase A is maintained at 98-99%.

[0012] Furthermore, the mass spectrometry conditions in the supercritical fluid chromatography-tandem mass spectrometry are as follows: the scanning mode is positive ion scanning; the MRM mode is adopted for acquisition; the electrospray ion source has an ion source temperature of 140-160°C; the capillary voltage is 2.6-3.0 kV; the cone gas flow rate is 60-80 L / h; the desolvation gas flow rate is 600-800 L / h; and the desolvation gas temperature is 300-350°C.

[0013] Further preferably, the ion source temperature is 140-150°C; the capillary voltage is 2.6-2.8 kV; the cone gas flow rate is 70-80 L / h; the desolvation gas flow rate is 650-700 L / h; and the desolvation gas temperature is 310-330°C.

[0014] Furthermore, the preparation steps of the isotope mixed internal standard solution are: dissolving the standard products of the internal standards corresponding to various phthalates in n-hexane and then fixing the volume to obtain the standard stock solutions of the internal standards corresponding to various phthalates; taking the standard stock solutions of the internal standards corresponding to various phthalates respectively, mixing them and fixing the volume with n-hexane to obtain the isotope mixed internal standard solution.

[0015] Furthermore, the ratio of the sample to n-hexane is 0.18-0.22 g: 7-12 mL.

[0016] Furthermore, the mass ratio of the spherical carbon to the sample is 4-6:0.01-0.03.

[0017] Furthermore, the extraction is oscillation extraction at a rate of 200-250 r / min, and the oscillation extraction time is 8-12 min.

[0018] The technical solution of the present invention has the following advantages:

[0019] 1. The present invention provides a method for determining phthalates in water-based adhesives. Spherical carbon and n-hexane are used to extract the water-based adhesive sample. This method combines sample extraction and purification, making the operation simpler and faster. The spherical carbon effectively adsorbs and purifies polar and non-polar non-target substances in the water-based adhesive, avoiding the loss of the test components caused by sample concentration and purification. Phthalate esters in the water-based adhesive are analyzed and determined using SFC-MS / MS using a Viridis HSS C18 SB column. This accelerates the separation of target components and impurities, reduces solvent consumption, and improves quantitative results.

[0020] 2. In the method for determining phthalates in water-based adhesives provided by the present invention, supercritical CO2 is used as mobile phase A, and one or more of methanol, ethanol, and isopropanol are used as mobile phase B; the total flow rate after the two phases are mixed is 0.7-1.0 mL / min; the column temperature is 45-50°C; the injection volume is 2-3 μL, and the elution method is gradient elution, which has the advantages of fast separation speed and strong specificity. By optimizing the instrument detection conditions, the chromatographic separation time is greatly shortened and the separation degree is good (baseline separation).

[0021] 3. In the method for determining phthalates in water-based adhesives provided by the present invention, the chromatographic column of the SFC-MS / MS adopts the chromatographic test conditions and the gradient elution mode, in which the volume ratio of mobile phase A is reduced from 95%-99% to 85%-89% within 0-3.5 minutes and then restored to 95%-99% within 3.5-6 minutes. The use of gradient elution helps to achieve effective separation of the components to be tested and improve the accuracy of the test results.

[0022] 4. The method for determining phthalates in water-based adhesives provided by the present invention can effectively extract the components to be tested from the water-based adhesive sample by adjusting the dosage of n-hexane and spherical carbon within a suitable range, thereby reducing the use of organic solvents, lowering costs, and reducing pollution to the environment. Selecting the particle size of the spherical carbon to be within the range of 0.5 to 1 μm not only ensures that the spherical carbon has a large surface area, achieves effective adsorption of non-target substances, achieves separation, and shortens the extraction time of the sample solution to be tested. Appropriate oscillation rate and extraction time can improve the extraction effect of the spherical carbon on the components to be tested and save time and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is a flow chart of the determination method of the present invention;

[0025] Figure 2 is a chromatogram of the sample to be tested in Example 1 with the added phthalate content of 5.0 μg / g;

[0026] Figure 3 This is the chromatogram of the sample to be tested in Comparative Example 1, in which the content of phthalate esters added was 5.0 μg / g. DETAILED DESCRIPTION

[0027] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0028] If specific experimental procedures or conditions are not specified in the examples, the procedures or conditions described in the literature in the field can be followed. Reagents or instruments used without manufacturer's indication are commercially available. All standards used in this invention were purchased from Shanghai Anpu Experimental Technology Co., Ltd., with a purity greater than 99.5%. Multi-walled carbon nanotubes were purchased from Shanghai Anpu Technology Co., Ltd.

[0029] Example 1

[0030] This embodiment provides a specific method and process for determining phthalates in water-based adhesives. Figure 1As shown, the specific steps include:

[0031] (1) Weigh 0.2 g of water-based glue into a 20 mL glass conical flask, add 2 mL of ultrapure water to disperse it, then add 100 μL of isotope mixed internal standard solution, 8 mL of n-hexane, and 50 mg of spherical carbon in sequence. Oscillate and extract for 10 min (speed 200 r / min) to obtain the extract; then take the supernatant, centrifuge, and filter to obtain the sample solution to be tested.

[0032] (2) The preparation steps of the isotope mixed internal standard solution are as follows: weigh 10 mg (accurate to 0.1 mg) of the corresponding internal standard standard of each phthalate ester (i.e., DPHP, BBP, DEEP, DMEP) into a 10 mL volumetric flask, dissolve it with n-hexane and dilute to the mark to obtain the standard stock solution of the corresponding internal standard of each phthalate ester; transfer 1 ml of the corresponding internal standard stock solution of each phthalate ester into the same 100 mL volumetric flask, dilute to the mark with n-hexane to obtain a 10 μg / mL isotope mixed internal standard solution, and store it in a dark place at -18°C.

[0033] (3) Preparation of mixed standard working solution: Pipette 1 mL of 100 μg / mL phthalate mixed solution (i.e., the concentration of DPHP, BBP, DEEP, and DMEP are all 100 μg / mL) into a 10 mL volumetric flask, dilute to volume with n-hexane, and prepare a 10 μg / mL mixed standard stock solution; pipette 0.02 ml, 0.05 ml, 0.1 ml, 0.2 ml, 0.5 ml, and 1 ml of the mixed standard stock solution into a 10 mL volumetric flask, add 100 μL of the isotope mixed internal standard solution, and dilute to volume with n-hexane to prepare mixed standard working solutions of different concentrations, with the concentration sequence being: 20, 50, 100, 200, 500, and 1000 ng / mL;

[0034] (4) Obtaining the standard curve: The prepared mixed standard working solutions of different concentrations were injected into the SFC-MS / MS, and the internal standard method was used for quantitative analysis of phthalates. That is, the peak area of ​​each standard sample and its corresponding internal standard peak area ratio (y) and its concentration (x) were subjected to linear regression analysis to obtain the standard curve.

[0035] (5) Analysis of the sample solution: The sample solution obtained in step (1) was injected into SFC-MS / MS for measurement. The chromatographic peak area ratio of phthalate esters and internal standard was measured and substituted into the standard curve to determine the content of phthalate esters in the sample.

[0036] The chromatographic conditions used in the determination were as follows: Viridis HSS C18 SB column (3 mm × 100 mm, 1.8 μm, Waters, USA); mobile phase A was supercritical CO2, and mobile phase B was ethanol; the flow rate after the two phases were mixed was 0.7 mL / min; the column temperature was 45°C; the injection volume was 2 μL; the elution method was gradient elution, and the gradient elution program is shown in the following table.

[0037] 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

[0038] The mass spectrometry conditions used in the determination were as follows: positive ion scanning; electrospray ion source; ion source temperature of 140°C; capillary voltage of 2.6 kV; cone gas flow rate of 70 L / h; desolvation gas flow rate of 650 L / h; desolvation gas temperature of 310°C; MRM mode acquisition, MRM parameters are shown in the table below.

[0039]

[0040]

[0041] *Quantitative ion

[0042] The chromatogram of the water-based adhesive sample recorded by the method of Example 1 is as follows: Figure 2 shown.

[0043] Example 2

[0044] This example provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, except that: when extracting the sample solution to be tested, 9 mL of n-hexane is used to extract 0.18 g of the sample to be treated, and the spherical carbon is 45 mg.

[0045] Example 3

[0046] This example provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, except that: when extracting the sample solution to be tested, 11 mL of n-hexane is used to extract 0.22 g of the sample to be treated, and the spherical carbon is 55 mg.

[0047] Example 4

[0048] This example provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, except that the oscillation extraction rate is 250 r / min.

[0049] Example 5

[0050] This example provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, except that the total flow rate after the two phases are mixed is 1.0 mL / min.

[0051] Example 6

[0052] This example provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, with the only difference being that during SFC-MS / MS separation, the column temperature is 50° C. and the injection volume is 3 μL.

[0053] Example 7

[0054] This embodiment provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, with the following differences: the ion source temperature is 150°C; the capillary voltage is 2.8kV; the cone gas flow rate is 80L / h; the desolvation gas flow rate is 700L / h; and the desolvation gas temperature is 330°C.

[0055] Example 8

[0056] This example provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, except that the gradient elution procedure is different, see the table below.

[0057] 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

[0058] Comparative Example 1

[0059] The sample solution treatment and detection methods in this comparative example were the same as those described in "Determination of Phthalate Esters in Cigarette Water-Based Adhesives by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry" (Yan Jin et al., Journal of Analysis and Testing, 2015, 34(2):134-140). The recovery rate was 78.3-87.7%, which was significantly lower than that of the present invention because the matrix effect was not considered.

[0060] Comparative Example 2

[0061] The sample solution treatment method in this comparative example is the same as that in Example 1, and the detection method is the same as that in "Determination of Phthalates in Water-Based Latex for Tobacco Use by Gas Chromatography / Mass Spectrometry" (Yang Bin et al., Tobacco Science and Technology, 2011, 7:48-51). This method takes a long time for separation and pretreatment, and is not suitable for routine large-scale sample testing.

[0062] Comparative Example 3

[0063] This comparative example provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, except that the chromatographic column used is Viridis BEH (2.1 mm × 100 mm, 1.7 μm). Figure 3 As shown, the phthalates have poor peak shape and resolution.

[0064] Comparative Example 4

[0065] This comparative example provides a specific method for determining phthalates in water-based adhesives, which is basically the same as Example 1, except that the spherical carbon in Example 1 is replaced by multi-walled carbon nanotubes with a particle size of 0.5 to 1 μm.

[0066] Experimental Example 1

[0067] The analysis time of each embodiment and comparative example in the mass spectrometer is recorded as the separation time; the time of the sample treatment stage is the pretreatment time; the recovery rate and average relative standard deviation (RSD) of phthalates and the amount of organic solvent used are as shown in the following table.

[0068]

[0069]

[0070] As can be seen from the table above, Comparative Example 1 has a lower recovery rate, longer separation time, and consumes more toxic and hazardous solvents than Example 1. Comparative Example 4 has a lower recovery rate than Example 1, indicating that the spherical carbon has a better purification effect on interfering substances in the water-based adhesive, the extract matrix is ​​less, and the results are more accurate after internal standard correction. The pretreatment method of the present invention can better remove impurities and reduce interference with the test results.

[0071] Experimental Example 2

[0072] (1) Sensitivity detection

[0073] Spiked samples of varying concentrations (0.05, 0.10, 0.2, and 0.40 mg / kg) were prepared from blank water-based adhesive samples. After extraction and purification, these samples were injected into a SFC-MS / MS. The concentration that yielded a signal-to-noise ratio of 3 (S / N=3) was used as the method's limit of detection (LOD), and the concentration that yielded a signal-to-noise ratio of 10 (S / N=3) was used as the method's limit of quantification (LOQ). The method's detection limits for phthalates (i.e., DPHP, BBP, DEEP, and DMEP) were 0.05-0.09 μg / g and 0.25-0.30 μg / g, respectively.

[0074] (2) Accuracy and repeatability

[0075] In Example 1, the peak area of ​​each phthalate standard sample and its corresponding internal standard peak area ratio (y) and its concentration (x) were subjected to linear regression analysis to obtain a standard curve, as shown in the table below.

[0076] To determine the repeatability of the assay method of the present invention, 0.1 ml of a 10 μg / mL phthalate ester solution was added to 0.2 g of a blank sample, resulting in a phthalate ester content of 5.0 mg / kg. The spiked samples were then assayed according to the method of Example 1. The experiment was repeated five times, and the recovery rates were calculated based on the spiked amounts and the measured values. The results are shown in the table below.

[0077]

[0078]

[0079] As can be seen from the table above, the average recovery rate of phthalates is between 93.5% and 98.7%, and the average relative standard deviation (RSD) is less than 5.0%, indicating that the determination method of the present invention has a high recovery rate, is stable, and has good repeatability.

[0080] The DMEP content in the spiked sample of 5.0 mg / kg measured by the detection methods of Example 1 and Comparative Example 2 was 4.97 and 4.15 mg / kg, respectively, indicating that the determination method of the present invention has better accuracy, is environmentally friendly, efficient, and time-saving.

[0081] Can find by the measurement result of embodiment and comparative example, the present invention is economical, environmentally friendly, efficient.And for the characteristics of water-based glue, select spherical carbon as purification material, not only can well remove the interfering substances in the matrix, and can obtain good recovery rate.Can find by the measurement result of embodiment 1 and comparative example, the pre-treatment condition adopted by the present invention is simple, will extract and purify and integrate into one, do not use the large organic solvent of toxicity.After isotope internal standard corrects matrix effect, have better accuracy.

[0082] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for determining phthalates in water-based adhesives, characterized in that: The following steps are involved: (1) Weigh the sample, disperse it in water, add isotope mixed internal standard solution, extract it with n-hexane and spherical carbon, and then centrifuge and filter to obtain the sample solution to be tested; (2) The sample solution is measured and analyzed by supercritical fluid chromatography-tandem mass spectrometry; the supercritical fluid chromatography column in the supercritical fluid chromatography-tandem mass spectrometry is Viridis HSS C18 SB; The chromatographic column conditions are as follows: mobile phase A is supercritical CO2, mobile phase B is ethanol; the total flow rate after the two phases are mixed is 0.7-1.0 mL / min; the column temperature is 45-50°C; the injection volume is 2-3 μL, and the elution method is gradient elution; The gradient elution is as follows: at 0-1 min, the volume proportion of mobile phase A is 98-99%; at 1-2.5 min, the volume proportion of mobile phase A decreases from 98-99% to 95-96%; at 2.5-3.2 min, the volume proportion of mobile phase A decreases from 95-96% to 88-90%; at 3.2-4.0 min, the volume proportion of mobile phase A remains at 88-90%; at 4.0-4.5 min, the volume proportion of mobile phase A increases from 88-90% to 98-99%; and at 4.5-6.0 min, the volume proportion of mobile phase A remains at 98-99%.

2. The method for determining phthalates in water-based adhesives according to claim 1, wherein The mass spectrometry measurement conditions in the supercritical fluid chromatography-tandem mass spectrometry are as follows: the scanning mode is positive ion scanning; the MRM mode is adopted for acquisition; the electrospray ion source has an ion source temperature of 140-160°C; the capillary voltage is 2.6-3.0 kV; the cone gas flow rate is 60-80 L / h; the desolvation gas flow rate is 600-800 L / h; and the desolvation gas temperature is 300-350°C.

3. The method for determining phthalates in water-based adhesives according to claim 1 or 2, wherein: The mass spectrometry measurement conditions in the supercritical fluid chromatography-tandem mass spectrometry are preferably: ion source temperature of 140-150°C; capillary voltage of 2.6-2.8kV; cone gas flow rate of 70-80L / h; desolvation gas flow rate of 650-700L / h; and desolvation gas temperature of 310-330°C.

4. The method for determining phthalates in water-based adhesives according to claim 1, wherein: The preparation steps of the isotope mixed internal standard solution are as follows: dissolving the corresponding internal standard standards of various phthalates in n-hexane respectively and then diluting the volume to obtain the standard stock solutions of the corresponding internal standards of various phthalates; and taking the corresponding internal standard standard stock solutions of various phthalates respectively, mixing them and then diluting the volume with n-hexane to obtain the isotope mixed internal standard solution.

5. The method for determining phthalates in water-based adhesives according to any one of claims 1 to 4, wherein: The ratio of the sample usage to n-hexane usage is 0.18-0.22 g: 7-12 mL.

6. The method for determining phthalates in water-based adhesives according to any one of claims 1 to 5, characterized in that: The mass ratio of the spherical carbon to the sample is 4-6:0.01-0.

03.

7. The method for determining phthalates in water-based adhesives according to claim 1, wherein The extraction is oscillation extraction at a rate of 200-250 r / min, and the oscillation extraction time is 8-12 min.

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