A gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV adhesive

Abstract

The present invention belongs to the technical field of analytical chemistry, and discloses a gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue, comprising the following steps: after curing the UV adhesive, extracting the extracted supernatant, concentrating it, and settling it to 2-3 ml to obtain an extract, eluting the extract and collecting the eluent, blowing the eluent to near dryness, settling it to 1-2 ml, filtering it through a filter membrane to obtain a solution to be tested, and detecting the solution to be tested by GC-MS. The present invention optimizes the instrumental analysis parameters, and after separation by two chromatographic columns, HP-5ms or DB-5ht, the target compound 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester can obtain a symmetrical chromatographic peak within 8 minutes, with a symmetrical peak shape and little matrix interference. The analytical test method has a low detection limit, good precision, and a high sample spike recovery rate.

Description

Technical Field

[0001] The invention belongs to the technical field of analytical chemistry, and in particular relates to a gas chromatography-mass spectrometry method for determining the residual amount of a photoinitiator TPO-L in a UV glue. Background Art

[0002] 2,4,6-Trimethylbenzoylphenylphosphonic acid ethyl ester (photoinitiator TPO-L) is a liquid photoinitiator, which is widely used in UV curing coatings, printing inks, UV curing adhesives, optical fiber coatings and other fields. Initiator TPO-L has excellent yellowing resistance, low migration and low odor characteristics, and has high photoinitiator activity. It is particularly suitable for UV curing of white systems and thick films. The curing speed is very fast and it is suitable for low yellowing and low odor formulation systems.

[0003] In recent years, studies have found that after adhesives and inks are cured, residual photoinitiators exist, which can affect the human body through chemical migration or physical contact pollution. Related toxicological studies have also proved that photoinitiators can have adverse effects on human health. In order to regulate the use of photoinitiators, European and American countries have successively promulgated regulations and permission lists to restrict the use of photoinitiators. In 2007, in the EU's "Res AP (2002) Resolution of some member states on paper and paperboard materials and products intended to come into contact with food" 1, Michler's ketone photoinitiator was clearly banned. In 2010, the European Printing Ink Association (EuPIA) clearly proposed the limit requirements for 8 small molecule photoinitiators, including methyl benzophenone, methyl o-benzoylbenzoate, ethyl p-N,N-dimethylaminobenzoate and isopropylthioxanthone.

[0004] The United Nations Globally Harmonized System of Classification and Labelling of Chemicals (GHS) hazard classification classifies the photoinitiator TPO-L as Category 1B (skin sensitizer) and Category 2 (hazardous to the aquatic environment), which means that it may cause skin allergic reactions in humans and is toxic to aquatic life with long-lasting effects.

[0005] Table 1 Basic information of target compounds

[0006]

[0007] The existing technologies mainly involve the detection of various ketones and some commonly used photoinitiators, such as (1) Xu Wenyang, Chen Hua. Simultaneous detection of 14 photoinitiators in high-fat foods by gas chromatography-mass spectrometry [J]. Food and Machinery, 2018, 34(08): 54-59; (2) Zhao Lei, Yuan Linyan, Han Chen. Determination of the content of 11 photoinitiators in UV inks used in food packaging industry by gas chromatography-mass spectrometry [J]. Journal of Food Safety and Quality, 2020, 11(07): 2162-2167; (3) Liu Yan. Study on the gas chromatography-mass spectrometry test method for 9 photoinitiators in food packaging materials [D]. Donghua University, 2017; (4) Li Zhonghao, Bian Zhaoyang, Tang Gangling, Fan Ziyan, Yang Fei, Liu Nan, Hu Qingyuan, Zhang Hongfei, Chen Huan, Li Xue, Jiang Xingyi. A detection method for 16 photoinitiators in paper printing packaging materials [P]. CN102818874B, 2014. There is no report on the detection method of the initiator 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester (photoinitiator TPO-L).

[0008] In addition, CN110988170A only detects (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, and the instrument detection method used is UPLC-MS / MS. CN114184715A uses UPLC-MS / MS for the determination of 20 photoinitiators.

[0009] At present, the research on photoinitiator TPO-L is mainly focused on the synthesis and application fields. Only high performance liquid chromatography has been established for the detection of its residual amount in the product. There is no report on the determination of photoinitiator TPO-L by gas chromatography-mass spectrometry. The detector sensitivity of high performance liquid chromatography is not as good as that of gas chromatography, the instrument is relatively expensive, and the solvent needs to be strictly purified. Considering the detection cost and the convenience of the method, a gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue is proposed, which provides a variety of simple and efficient method options for the safety research of photoinitiator TPO-L. Summary of the invention

[0010] The present invention proposes a gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV adhesive. The method is simple, rapid and highly accurate, and can provide technical support in detection and analysis for the safety assessment of photoinitiator TPO-L in adhesives and related products.

[0011] The present invention is achieved through the following technical solutions:

[0012] A gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue comprises the following steps:

[0013] (1) After curing the UV adhesive, an organic solvent is added for extraction, the supernatant obtained by extraction is concentrated to near dryness, an organic solvent is added to make the volume to 2-3 ml to obtain an extract, the extract is purified by an ENVI-18 column, the eluate is eluted and collected, the eluate is concentrated to near dryness, the organic solvent is added to make the volume to 1-2 ml, and the sample solution to be tested is obtained by filtering through a filter membrane;

[0014] (2) Preparation of standard working solutions: Prepare standard working solutions of 0.5 mg / L, 1.0 mg / L, 2.0 mg / L, 5.0 mg / L, and 10.0 mg / L using standard substances;

[0015] (3) Detection by gas chromatography-mass spectrometry

[0016] The standard working solution in step (2) is subjected to gas chromatography-mass spectrometry detection, and a standard working curve is drawn according to the standard solution concentration-chromatographic peak area;

[0017] The sample solution obtained in step (1) is subjected to gas chromatography-mass spectrometry under the same conditions, wherein the gas chromatography conditions are:

[0018] Chromatographic column: Agilent gas chromatography column HP-5ms, 30m (length) × 0.25mm (inner diameter) × 0.25μm (film thickness) or Agilent gas chromatography column DB-5ht, 15m (length) × 0.25mm (inner diameter) × 0.1μm (film thickness), injection port temperature: 230-300℃, injection mode: splitless, column flow rate: 0.8-1.2mL / min, heating program: initial temperature 80-120℃, hold for 1-2min, heat up to 250-300℃ at 20-40℃ / min, hold for 1-5min, then heat up to 310-330℃ at 20-30℃ / min, hold for 2-5min;

[0019] The mass spectrometry conditions were:

[0020] Ion source: EI source, ionization energy: 70 eV, ion source temperature: 220-240 °C, quadrupole temperature: 140-160 °C, solvent delay: 4.5-6 min, acquisition mode: SIM and scan, quantitative ion (m·z -1 ): 147, qualitative ion (m·z -1 ): 119,77;

[0021] (4) Calculation: Substitute the measured chromatographic peak area of ​​the photoinitiator TPO-L in the test solution into the standard curve to obtain the concentration of the photoinitiator TPO-L in the test solution, and then calculate the residual amount of the photoinitiator TPO-L in the UV glue based on the sample mass corresponding to the test solution. The calculation formula is:

[0022] X=C×V×f / m,

[0023] Wherein, X is the content of photoinitiator TPO-L in the sample, mg / kg;

[0024] C is the concentration of photoinitiator TPO-L in the sample, mg / L;

[0025] V is the final fixed volume, mL;

[0026] M is the sample mass, g;

[0027] F is the dilution factor.

[0028] Preferably, the gas chromatography conditions are:

[0029] Chromatographic column: injection port temperature: 290℃, injection mode: splitless, column flow rate: 1.0mL / min, heating program: initial temperature 120℃, hold for 1min, increase the temperature to 250℃ at 40℃ / min, hold for 1min, then increase the temperature to 320℃ at 20℃ / min, hold for 2min;

[0030] The mass spectrometry conditions are:

[0031] Ion source: EI source, ionization energy: 70 eV, ion source temperature: 230 °C, quadrupole temperature: 150 °C, solvent delay: 4.5 min, acquisition mode: SIM and scan, quantitative ion (m·z -1 ): 147, qualitative ion (m·z -1 ):119,77.

[0032] Preferably, the organic solvent is one of acetone, methanol, acetonitrile and ethyl acetate.

[0033] Preferably, the organic solvent is ethyl acetate.

[0034] Preferably, the extraction method is ultrasonic extraction, and the extraction agent conditions are: extraction temperature is 60-80° C., and extraction time is 60-120 min.

[0035] Preferably, the extraction conditions are as follows: 1 g of UV adhesive is added with 25 to 40 mL of extractant, the extraction temperature is 60° C., and the extraction time is 60 min.

[0036] Preferably, the centrifugation condition is a rotation speed of 5000-8000 r / min for 2-5 min.

[0037] Preferably, the curing process is to place the UV adhesive on aluminum foil with a wavelength of 365nm and a radiation intensity of 36.8mw / cm 2 Carry out curing treatment, treating 0.1g sample for 25 to 30 seconds.

[0038] Preferably, the pore size of the filter membrane is 0.45 μm.

[0039] Preferably, the photoinitiator TPO-L is ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] (1) The present invention establishes a gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue.

[0042] (2) Through the optimization of instrumental analysis parameters, the target compound 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester can be separated by HP-5ms and DB-5ht columns to obtain symmetrical chromatographic peaks within 8 minutes with symmetrical peak shapes and little matrix interference.

[0043] (3) The analytical test method has a low detection limit, good precision, and high sample spike recovery, meeting the test requirements of the target compound. The target compound showed a good linear relationship in the range of 0.5 to 10.0 mg / L (r 2 >0.9999); the detection limit and quantification limit were both low, 0.0155mg / L and 0.0518mg / L respectively; the relative standard deviation was less than <1.5%; the sample spike recovery was 98.8% to 100.4%. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is the response intensity of the photoinitiator TPO-L in different solvents, ACN, MeOH, AC and EAC represent acetonitrile, methanol, acetone and ethyl acetate, respectively.

[0045] Figure 2 This is the chromatogram corresponding to the HP-5ms column.

[0046] Figure 3 This is the chromatogram corresponding to the DB-5ht column.

[0047] Figure 4 This is the mass spectrum of the photoinitiator TPO-L.

[0048] Figure 5 This is the standard working curve of photoinitiator TPO-L.

[0049] Figure 6 This is the total ion current TIC spectrum of sample 1 in Example 6. DETAILED DESCRIPTION

[0050] The present invention is further described in detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto. For process parameters not particularly noted, conventional techniques may be used.

[0051] Main instruments and reagents:

[0052] 7890B-5977B gas chromatograph-mass spectrometer, Agilent Technologies, Inc.

[0053] 2300HT ultrasonic cleaner, Shanghai Anpu Scientific Instrument Co., Ltd.;

[0054] X205BDU precision electronic analytical balance (sensitivity: 0.01 mg), Mettler, Switzerland;

[0055] LT-UV-X1000 box-type UV curing machine, Lituo testing equipment;

[0056] Ethyl 2,4,6-trimethylbenzoylphenylphosphonate standard: purity ≥98%, Tokyo Chemical Industry Co., Ltd.;

[0057] Methanol, acetonitrile, acetone, ethyl acetate: (HPLC grade, Sigma, USA).

[0058] Example 1 Selection of extraction solvent

[0059] The photoinitiator TPO-L contains olefin and ester structures. According to the principle of similar dissolving, an organic solvent with good fat solubility should be selected as the extraction solvent. Therefore, this embodiment selects acetone, methanol, acetonitrile, and ethyl acetate as solvents for testing. Four solvents were used to prepare 10ppm mixed standard solutions of target compounds, and the response intensity was compared under the same instrument conditions. The response intensity of each target substance in different solvents is different, which may be related to the expansion coefficient, boiling point and solubility of the target substance in the solvent. The response intensity corresponding to the target substance TPO-L is: acetonitrile>ethyl acetate>methanol>acetone. In addition, acetonitrile is an amphiphilic solvent with good water solubility and fat solubility. Adhesives include oil-based adhesives and water-based adhesives, which are suitable for the extraction of these two types of adhesives. Taking all factors into consideration, acetonitrile is used as the extraction solvent.

[0060] Example 2

[0061] 1. Sample pretreatment

[0062] Accurately weigh 0.4g (accurate to 0.1mg) of UV adhesive sample and place it on aluminum foil. Use a wavelength of 365nm and an ultraviolet radiation intensity of 36.8mw / cm 2The sample was cured by a UV curing machine for 100 seconds. After the curing treatment, the sample was placed in a sample bottle, 10 mL of acetonitrile was added, and the bottle cap was tightened before placing the sample in an ultrasonic cleaner. The sample was ultrasonicated at 60 ° C for 60 minutes and centrifuged at 5000 r / min for 5 minutes. The supernatant was transferred to another clean centrifuge tube, and 2 ml of acetonitrile was added to the solid residue. The above steps were repeated for extraction twice. Finally, the supernatants obtained from the three extractions were combined, concentrated to near dryness by nitrogen blowing, and acetonitrile was added to make the volume 2 ml. 5 ml of n-hexane and 5 ml of acetonitrile were used to activate the ENVI-18 column in turn, and the extract was loaded onto the activated small column. After loading, 10 ml of acetonitrile was used for elution and collection. The eluate was blown to near dryness by nitrogen blowing, and the acetonitrile was made to make the volume 1 ml. After filtering through a 0.45 μm filter membrane, the sample solution to be tested was obtained, and GC-MS was used for determination.

[0063] 2. Preparation of standard solution

[0064] Standard stock solution: Use a 100,000 grade analytical balance to accurately weigh 10 mg of ethyl 2,4,6-trimethylbenzoylphenylphosphonate standard, dissolve it in acetonitrile and make up to volume in a 10 mL volumetric flask to obtain a 1000 mg / L stock solution of the standard substance, and store it in a refrigerator at 4°C away from light.

[0065] Standard working solution: Dilute the standard stock solution stepwise with acetonitrile to obtain a series of mixed standard working solutions of 0.5 mg / L, 1.0 mg / L, 2.0 mg / L, 5.0 mg / L, and 10.0 mg / L.

[0066] 3. Instrument method conditions

[0067] Gas chromatography conditions:

[0068] Chromatographic column: HP-5ms (length 30m, inner diameter 0.25mm, film thickness 0.25μm) / DB-5ht (length 15m, inner diameter 0.25mm, film thickness 0.1μm), inlet temperature: 290℃, injection mode: non-divided flow, column flow rate: 1mL / min, heating program: initial temperature 120℃, hold for 1min, increase the temperature to 250℃ at 40℃ / min, hold for 1min, then increase the temperature to 320℃ at 20℃ / min, hold for 2min.

[0069] Mass spectrometry conditions:

[0070] Ion source: EI source, ionization energy: 70 eV, ion source temperature: 230 °C, quadrupole temperature: 150 °C, solvent delay: 4.5 min, acquisition mode: SIM and scan, quantitative ion (m·z -1 ): 147, qualitative ion (m·z -1 ):119,77.

[0071] Example 3 Detection limit test

[0072] According to the instrument method conditions of Example 2, the linear range determination and minimum detection limit test were carried out on the target TPO-L. The standard stock solution was diluted stepwise with acetonitrile to 0.5 mg / L, 1.0 mg / L, 2.0 mg / L, 5.0 mg / L, and 10.0 mg / L series of mixed standard working solutions. The standard working curve was drawn with mass concentration X (mg / L) as the horizontal coordinate and peak area Y as the vertical coordinate. The linear regression equation and other parameters of the obtained test object are shown in Table 2. It can be seen from the data in Table 2 that within the linear range of 0.5 mg / L to 10.0 mg / L, the photoinitiator TPO-L shows a good linear relationship, and its detection limit (LOD) and quantification limit (LOQ) are both low, 0.0155 mg / L and 0.0518 mg / L, respectively.

[0073] Table 2 Linear regression equation and other parameters of photoinitiator TPO-L

[0074]

[0075] Example 4 Precision Experiment

[0076] Table 3 Precision test results of photoinitiator TPO-L

[0077]

[0078] As shown in Table 3, under the conditions of this method, a sample without the analyte was selected as the blank matrix, and three different spike concentration levels (0.5 mg / L, 2.0 mg / L, and 10.0 mg / L) were set. The measurement was repeated three times, and the relative standard deviation was <1.5%, indicating that the test method has good repeatability and high precision.

[0079] Example 5 Accuracy Experiment

[0080] The accuracy test was conducted by blank matrix spike experiment. Samples without the analyte were selected as blank matrix, and three different spike concentration levels (0.5 mg / L, 2.0 mg / L, 10.0 mg / L) were set. Each spike level was tested 6 times in parallel (n=6) to conduct accuracy experiments. Under the three spike levels, the spike recovery rate of each target was in the range of 98.8% to 100.4% (see Table 4), indicating that the method has high accuracy and can meet the test requirements.

[0081] Table 4 Accuracy test results of photoinitiator TPO-L

[0082]

[0083] Example 6 Sample Test

[0084] The test solution obtained in Example 2 was subjected to GC-MS measurement according to the instrument method conditions of Example 2 to obtain Spectrum 6, and the chromatographic peak area of ​​TPO-L in the sample was measured and substituted into the standard curve to obtain the concentration of TPO-L in the sample. Then, the residual amount of TPO-L in the sample was calculated based on the mass corresponding to the test solution.

[0085] The calculation formula is:

[0086] X=C×V×f / m,

[0087] Wherein, X is the content of photoinitiator TPO-L in the sample, mg / kg;

[0088] C is the concentration of photoinitiator TPO-L in the sample, mg / L;

[0089] V is the final fixed volume, mL;

[0090] M is the sample mass, g;

[0091] F is the dilution factor.

[0092] Test results such as Figure 6 , from the spectrum Figure 6 It can be seen that the sample test can obtain a symmetrical TPO-L chromatographic peak with a symmetrical peak shape and little matrix interference.

[0093] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue, characterized in that: The steps include: (1) After curing the UV adhesive, an organic solvent is added for extraction, the supernatant obtained by extraction is concentrated to near dryness, an organic solvent is added to make the volume to 2-3 ml to obtain an extract, the extract is purified by an ENVI-18 column, the eluate is eluted and collected, the eluate is concentrated to near dryness, the organic solvent is added to make the volume to 1-2 ml, and the sample solution to be tested is obtained by filtering through a filter membrane; (2) Preparation of standard working solutions: Use standard substances to prepare standard working solutions of 0.5 mg / L, 1.0 mg / L, 2.0 mg / L, 5.0 mg / L, and 10.0 mg / L; (3) Detection by gas chromatography-mass spectrometry The standard working solution in step (2) is subjected to gas chromatography-mass spectrometry detection, and a standard working curve is drawn according to the standard solution concentration-chromatographic peak area; Under the same conditions, the sample solution obtained in step (1) is subjected to gas chromatography-mass spectrometry detection; Gas chromatography conditions: Chromatographic column: HP-5ms, 30m×0.25mm×0.25μm or DB-5ht, 15m×0.25mm×0.1μm, injection port temperature: 230~300℃, injection mode: splitless, column flow rate: 0.8~1.2mL / min, heating program: initial temperature 80~120℃, hold for 1~2min, heat up to 250~300℃ at 20~40℃ / min, hold for 1~5min, heat up to 310~330℃ at 20~30℃ / min, hold for 2~5min; Mass spectrometry conditions: Ion source: EI source, ionization energy: 70 eV, ion source temperature: 220-240 °C, quadrupole temperature: 140-160 °C, solvent delay: 4.5-6 min, acquisition mode: SIM, quantitative ion (m·z -1 ): 147, qualitative ion (m·z -1 ): 119,77; (4) Calculation: Substitute the chromatographic peak area of ​​the photoinitiator TPO-L in the test solution into the standard working curve to obtain the concentration of the photoinitiator TPO-L in the test solution, and then calculate the residual amount of the photoinitiator TPO-L in the UV glue according to the sample mass corresponding to the test solution; The organic solvent is one of acetone, methanol, acetonitrile and ethyl acetate.

2. The gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue according to claim 1, characterized in that: The gas chromatography conditions are: Chromatographic column: injection port temperature: 290℃, injection mode: splitless, column flow rate: 1.0mL / min, heating program: initial temperature 120℃, hold for 1min, increase the temperature to 250℃ at 40℃ / min, hold for 1min, then increase the temperature to 320℃ at 20℃ / min, hold for 2min; The mass spectrometry conditions are: Ion source: EI source, ionization energy: 70 eV, ion source temperature: 230 °C, quadrupole temperature: 150 °C, solvent delay: 4.5 min, acquisition mode: SIM, quantitative ion (m·z -1 ): 147, qualitative ion (m·z -1 ):119,77.

3. The gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue according to claim 1, characterized in that: The extraction method is ultrasonic extraction, and the extraction agent conditions are: extraction temperature is 60-80° C., and extraction time is 60-120 min.

4. The gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue according to claim 3 is characterized in that: The extraction conditions are as follows: 1 g of UV adhesive is added with 25 to 40 mL of an extractant, the extraction temperature is 60° C., and the extraction time is 60 min.

5. The gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue according to claim 1, characterized in that: The curing process is to place the UV adhesive on aluminum foil, with a wavelength of 365nm and a radiation intensity of 36.8mw / cm 2 Carry out curing treatment, treating 0.1g sample for 25 to 30 seconds.

6. The gas chromatography-mass spectrometry method for determining the residual amount of photoinitiator TPO-L in UV glue according to claim 1, characterized in that: The pore size of the filter membrane is 0.45 μm.

7. The method for determining the residual amount of photoinitiator TPO-L in UV glue by gas chromatography-mass spectrometry according to claim 1, characterized in that: The photoinitiator TPO-L is ethyl 2,4,6-trimethylbenzoylphenylphosphonate; The calculation formula for the residual amount of photoinitiator TPO-L in the UV glue is: X=C×V×F / m, Wherein, X is the content of photoinitiator TPO-L in the sample, mg / kg; C is the concentration of photoinitiator TPO-L in the sample, mg / L; V is the final fixed volume, mL; m is the mass of the sample, g; F is the dilution factor.

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