A method for detecting phthalates in electronic and electrical products

Abstract

The invention relates to the technical field of chemical component detection, and specifically discloses a method for detecting phthalates in electronic and electrical products. The method comprises: performing multiple tests on a standard substance to obtain a relative standard deviation value; changing the number of tests to obtain multiple groups of relative standard deviation values ​​of different test numbers; obtaining a mean value of the relative standard deviation value; drawing a relative standard deviation analysis diagram and obtaining the area of ​​a shadow region; comparing and analyzing the area of ​​the shadow region to determine whether the multiple groups of relative standard deviation values ​​obtained are stable; comparing and analyzing the mean value of the relative standard deviation value to determine whether a retention time is stable; analyzing the relative standard deviation analysis diagram to obtain an optimal number of tests. The invention obtains the relative standard deviation values ​​of retention times of different test numbers and obtains the optimal number of tests through analysis, thereby facilitating providing guidance for subsequent experiments, quickly obtaining the relative standard deviation value, reducing experimental steps, saving experimental time and cost, and improving experimental efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of chemical component detection, and in particular to a method for detecting phthalates in electronic and electrical products. Background Art

[0002] Phthalates (PAEs) in electrical and electronic products are common hazardous substances, mainly used as plasticizers to make plastics easier to process and shape, and are widely used in the manufacture of electrical and electronic products. However, these substances are easily volatile during processing, and have exudative and migratory properties after being finished, which may cause harm to human health and the environment; phthalates are a class of environmental estrogens that mainly enter the human body through breathing, skin contact, and diet, interfering with the body's endocrine function and possibly causing reproductive, developmental, and behavioral abnormalities. In addition, phthalates are also considered to be an environmental hormone that may have long-term adverse effects on human health.

[0003] China Publication No. CN102419352B discloses a method for determining the total amount of phthalates, comprising: converting all phthalates in a sample into phthalic acid to obtain a sample solution; determining the content of phthalic acid in the sample solution by high performance liquid chromatography; and calculating the total amount of phthalates in the sample based on a peak area-mass concentration standard curve of a phthalic acid standard substance and a linear regression equation.

[0004] However, in traditional technologies, the method for detecting phthalates in electronic and electrical products is to test the stability of retention time, thereby performing multiple tests on standard substances, wherein the number of tests is often based on the experience of the experimenter and there is a great deal of uncertainty, thereby failing to ensure the accuracy of the stability of retention time. Summary of the invention

[0005] The object of the present invention is to provide a method for detecting phthalates in electronic and electrical products to solve the technical problems in the above background.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for detecting phthalates in electronic and electrical products, including a specific method for testing the stability of retention time:

[0008] A1: Test the standard substance multiple times and obtain the relative standard deviation value based on the retention time and the mean retention time of the standard substance;

[0009] A2: Repeat step A1 multiple times and change the number of tests to obtain multiple sets of relative standard deviation values ​​with different test times, and mark the relative standard deviation values ​​as DZ i, where i represents the i-th group test and i is a positive integer;

[0010] A3: Obtain the mean of the relative standard deviation value;

[0011] A4: Draw a relative standard deviation analysis chart and obtain the area of ​​the shaded region;

[0012] A5: Compare and analyze the areas of the shaded regions to determine whether the relative standard deviation values ​​obtained for multiple groups are stable;

[0013] A6: Compare and analyze the mean of relative standard deviation to determine whether the retention time is stable;

[0014] A7: Analyze the relative standard deviation analysis chart to obtain the optimal number of tests.

[0015] As a further solution of the present invention: the standard substances include: DIBP, DBP, BBP, DEHP.

[0016] As a further solution of the present invention: the method for obtaining the retention time of the standard substance is:

[0017] The standard substance is tested multiple times to obtain the retention time of the standard substance, and the retention time of the standard substance is marked as T DIBP，n , T DBP，n , T BBP，n , T DEHP，n , where n is the number of different tests and n is a positive integer.

[0018] As a further solution of the present invention: the method for obtaining the mean value of the retention time of the standard substance is:

[0019] According to the obtained retention time of the standard substance, the mean retention time of the standard substance is calculated and marked as

[0020] As a further solution of the present invention: the calculation method of the relative standard deviation value of the i-th group is:

[0021] By formula: The relative standard deviation parameters are calculated and marked as D DIBP , D DBP , D BBP , D DEHP , select the maximum value of the relative standard deviation parameters of the standard substance as the relative standard deviation value of the current test, and mark the relative standard deviation value of the current test as DZ i .

[0022] As a further solution of the present invention: the method for obtaining the mean value of the relative standard deviation value is:

[0023] The obtained multiple groups of relative standard deviation values ​​are averaged to obtain the mean of the relative standard deviation values, and the mean of the relative standard deviation values ​​is marked as

[0024] As a further solution of the present invention: the method for obtaining the area of ​​the shadow region is:

[0025] Based on the X-DZ two-dimensional coordinate system, a relative standard deviation analysis chart is drawn for multiple sets of relative standard deviation values. In the chart, the X axis represents the number of tests, and the DZ axis represents the relative standard deviation value. Multiple sets of relative standard deviation values ​​are connected to obtain a broken line, and the broken line and The area enclosed by the straight lines of the values ​​is obtained as the shaded area, thereby obtaining the area of ​​the shaded area, and the area of ​​the shaded area is marked as M.

[0026] As a further solution of the present invention: the method for determining whether the obtained multiple groups of relative standard deviation values ​​are stable is:

[0027] The shadow area threshold is preset as MY, and the shadow area M is compared with the shadow area threshold MY for analysis;

[0028] If M≤MY, the obtained multiple groups of relative standard deviation values ​​are determined to be stable, and the process goes to A6;

[0029] If M>MY, it is determined that the multiple sets of relative standard deviation values ​​obtained are unstable and cannot be used as experimental data, so it is necessary to obtain multiple sets of relative standard deviation values ​​again.

[0030] As a further solution of the present invention: the method for determining whether the retention time is stable is:

[0031] The relative standard deviation threshold is preset as DY, and the relative standard deviation mean is Compare and analyze with the relative standard deviation value threshold DY;

[0032] like The retention time is determined to be stable;

[0033] like The retention time is determined to be unstable.

[0034] As a further solution of the present invention: the method for obtaining the optimal number of tests is:

[0035] Based on the relative standard deviation analysis chart, a fitting straight line is obtained according to multiple sets of relative standard deviation values, and the mean of the relative standard deviation values ​​is obtained according to the fitting straight line. The corresponding test number CS is further rounded to obtain the optimal test number.

[0036] Beneficial effects of the present invention:

[0037] (1) The present invention obtains relative standard deviation values ​​of retention time at different test times, and analyzes multiple groups of relative standard deviation values ​​to determine whether they are stable, thereby determining whether the experiment is reliable. If the relative standard deviation value is unstable, it is necessary to check whether there are errors or interference factors in the experimental process, thereby improving the experimental method to ensure the accuracy of the experiment;

[0038] (2) The present invention obtains the relative standard deviation value of the retention time of different test times, analyzes and obtains the optimal test times, and records the optimal test times, so as to provide guidance for subsequent experiments, determine the appropriate test times, and quickly obtain the relative standard deviation value, thereby reducing the experimental steps, saving experimental time and cost, and improving experimental efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be further described below in conjunction with the accompanying drawings.

[0040] Figure 1 is a step diagram of a method for determining whether the retention time is stable in the present invention;

[0041] Figure 2 It is a step diagram of the method of the present invention;

[0042] Figure 3 1 is a diagram showing the steps for obtaining the relative standard deviation value in the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] See also Figure 1-3 As shown, the present invention is a method for detecting phthalates in electronic and electrical products, comprising the following steps:

[0045] Step 1: Disassemble and separate the electronic and electrical products into various single materials according to GB / T39560.2-2020, cut about 1 mg with a cutting knife or tweezers, or crush and mix the samples evenly, and then press them into thin sheets or films through a tablet press for analysis;

[0046] Step 2: Optimize the injection volume;

[0047] Weigh 0.3 mg, 0.5 mg, 1.0 mg, 1.5 mg, and 2.0 mg of standard substance samples for verification. The thermal analysis conditions adopt a heating program: initial temperature 50°C, increase to 300°C at a rate of 150°C / min, maintain for 1 min, carrier gas: nitrogen (purity ≥99.999%), injection time: 1 min.

[0048] According to the test results, the sample test result stability is better and the sample recovery rate is more stable as the sample weighing amount; for example, when the sampling amount is 1.0 mg, the sample test result stability is better and the sample recovery rate is more stable, so 1.0 mg is selected as the sample weighing amount;

[0049] Step 3: Optimize thermal analysis conditions;

[0050] According to the physical properties of phthalates such as boiling point, the sample weight was selected as 1.0 mg, and the test was carried out at a gradient of thermal desorption temperatures of 250, 275, 300, 325, 350 and 370°C, and the optimal thermal desorption temperature was selected based on the results; for example, when the temperature was 250, the recovery rate was low, and when the temperature was increased to 275, the DBP recovery rate was improved to a certain extent, but other phthalates did not change much, and when the temperature was 300°C, the RSD (RSD represents relative standard deviation) of each phthalate was the most stable. When it exceeded 300 degrees, the accuracy of the recovery rate decreased, so 300°C was selected as the optimal thermal desorption temperature;

[0051] Step 4: Selection of gas chromatography conditions;

[0052] Two chromatographic columns were used for comparative verification;

[0053] For example: Chromatographic column 1: Chromatographic column model: SE-54 (15m*0.25mm*0.10μm); Program temperature rise: 50℃, hold for 1min, increase to 280℃ at 20℃ / min, hold for 10min;

[0054] Chromatographic column 2: Chromatographic column model: ZB-1HT (30m*0.25mm*0.10μm); Program temperature rise: 50℃, hold for 1min, increase to 280℃ at 20℃ / min, hold for 5min, increase to 320℃ at 20℃ / min, hold for 2min;

[0055] Carrier gas: nitrogen (purity ≥ 99.999%); Inlet temperature: 250°C; FID detector temperature: 300°C; Column flow rate: 1 ml / min; Split ratio: 50:1;

[0056] By comparing chromatographic columns 1 and 2, it is found that the separation of the four substances is good. Considering the matrix interference in the actual sample, a 30m chromatographic column is selected for testing. When the matrix interference is small, a 15m chromatographic column can be used for testing to reduce the test time.

[0057] Step 5: Test the stability of retention time;

[0058] Test the standard substance several times to determine whether the retention time is stable;

[0059] A1: Test the standard substance multiple times and obtain the relative standard deviation value based on the retention time and the mean retention time of the standard substance;

[0060] Among them, standard substances include: DIBP, DBP, BBP, DEHP;

[0061] Multiple tests include: 5 times, 10 times, 15 times;

[0062] A11: Test the standard substance multiple times to obtain the retention time of the standard substance and mark the retention time of the standard substance as T DIBP，n , T DBP，n , T BBP，n , T DEHP，n , where n is the number of different tests and n is a positive integer;

[0063] A12: Based on the obtained retention time of the standard substance, calculate the mean retention time of the standard substance and mark the mean retention time as

[0064] A13: Calculate the relative standard deviation based on the retention time of the standard substance and the mean retention time;

[0065] By formula: The relative standard deviation parameters are calculated and marked as D DIBP , D DBP , D BBP , D DEHP , select the maximum value of the relative standard deviation parameters of the standard substance as the relative standard deviation value of the current test, and mark the relative standard deviation value of the current test as DZ i ;

[0066] A2: Repeat step A1 multiple times and change the number of tests to obtain multiple sets of relative standard deviation values ​​with different test times, and mark the relative standard deviation values ​​as DZ i , where i represents the i-th group test and i is a positive integer;

[0067] A3: Calculate the mean of the obtained multiple sets of relative standard deviation values ​​to obtain the mean of the relative standard deviation values, and mark the mean of the relative standard deviation values ​​as

[0068] A4: Draw a relative standard deviation analysis chart based on the X-DZ two-dimensional coordinate system. In the chart, the X axis represents the number of tests, and the DZ axis represents the relative standard deviation value. Connect the multiple relative standard deviation values ​​to obtain a broken line, and then use the broken line and The area enclosed by the straight line of the value is the shaded area, thereby obtaining the area of ​​the shaded area, and marking the area of ​​the shaded area as M;

[0069] A5: Compare and analyze the areas of the shaded regions to determine whether the relative standard deviation values ​​obtained for multiple groups are stable;

[0070] The shadow area threshold is preset as MY, and the shadow area M is compared with the shadow area threshold MY for analysis;

[0071] If M≤MY, the obtained multiple groups of relative standard deviation values ​​are determined to be stable, and the process goes to A6;

[0072] If M>MY, it is determined that the multiple sets of relative standard deviation values ​​obtained are unstable and cannot be used as experimental data, so it is necessary to obtain multiple sets of relative standard deviation values ​​again;

[0073] A6: Compare and analyze the mean of relative standard deviation to determine whether the retention time is stable;

[0074] The relative standard deviation threshold is preset as DY, and the relative standard deviation mean is Compare and analyze with the relative standard deviation value threshold DY;

[0075] like The retention time is determined to be stable;

[0076] like The retention time is determined to be unstable;

[0077] A7: Analyze the relative standard deviation analysis chart to obtain the optimal number of tests;

[0078] Based on the relative standard deviation analysis chart, a fitting straight line is obtained according to multiple sets of relative standard deviation values, and the mean of the relative standard deviation values ​​is obtained according to the fitting straight line. The corresponding test number CS is further rounded to obtain the optimal test number, and the optimal test number is recorded, so as to provide guidance for subsequent experiments, determine the appropriate test number, and quickly obtain the relative standard deviation value, reduce experimental steps, save experimental time and cost, and improve experimental efficiency;

[0079] Step 6: Method confirmation parameters, including: detection limit, precision and accuracy;

[0080] Among them, accuracy is: calibration with standard substances, blank experiments and spike recovery experiments to evaluate the accuracy of the detection method;

[0081] Detection limit: Use phthalate-free polyvinyl chloride (PVC) raw material, dissolve it in tetrahydrofuran, add a certain amount of 4 phthalate standard substances, mix well and air-dry, and use gas chromatography-mass spectrometry for accurate quantitative analysis. The measured results are DI BP concentration of 98 mg / kg, DBP concentration of 103 mg / kg, BBP concentration of 99 mg / kg, DEHP concentration of 102 mg / kg. This sample is used to verify the detection limit of the method;

[0082] Among them, phthalate-free means: does not contain phthalates;

[0083] Precision and accuracy: Three concentrations of samples were tested: low (concentration: 100 mg / kg), medium (concentration: 1000 mg / kg), and high (concentration: 3000 mg / kg). The test results are as follows:

[0084]

[0085]

[0086] Table 1 Low concentration precision (100 mg / kg)

[0087]

[0088] Table 2 Precision of medium concentration (1000 mg / kg)

[0089]

[0090] Table 3 High concentration precision (3000 mg / kg)

[0091] It has been verified that the precision of samples with three different concentrations is between 1.4% and 9.4%, and the accuracy is between 104% and 131%, which has good repeatability and accuracy.

[0092] Step 7: Actual sample test spectrum;

[0093] Common materials (such as PVC, SBS, ABS, PE, rubber, ink, etc.) were selected for actual sample and spiked test. By comparing the chromatogram of the actual sample with the chromatogram of the spiked sample, it was found that other compounds in the sample could have a good separation degree from the target compound.

[0094] Step 8: Inter-laboratory comparison test;

[0095] Select a number of companies, research institutes and third-party testing agencies to test PVC white, PVC, SBS, PE and rubber samples, and determine the accuracy of the content based on the test data;

[0096] Working principle of the present invention:

[0097] Step 1: Disassemble and separate electronic and electrical products into various single materials;

[0098] Step 2: Optimize the injection volume;

[0099] Step 3: Optimize thermal analysis conditions;

[0100] Step 4: Selection of gas chromatography conditions;

[0101] Step 5: Test the stability of retention time;

[0102] A1: Test the standard substance multiple times and obtain the relative standard deviation value based on the retention time and the mean retention time of the standard substance;

[0103] Among them, standard substances include: DI BP, DBP, BBP, DEHP;

[0104] A2: Repeat step A1 multiple times and change the number of tests to obtain multiple sets of relative standard deviation values ​​with different test times, and mark the relative standard deviation values ​​as DZ i , where i represents the i-th group test and i is a positive integer;

[0105] A3: Obtain the mean of the relative standard deviation value;

[0106] A4: Draw a relative standard deviation analysis chart and obtain the area of ​​the shaded region;

[0107] A5: Compare and analyze the areas of the shaded regions to determine whether the relative standard deviation values ​​obtained for multiple groups are stable;

[0108] A6: Compare and analyze the mean of relative standard deviation to determine whether the retention time is stable;

[0109] A7: Analyze the relative standard deviation analysis chart to obtain the optimal number of tests;

[0110] Step 6: Method confirmation parameters, including: detection limit, precision and accuracy;

[0111] Step 7: Actual sample test spectrum;

[0112] Step 8: Inter-laboratory comparison test.

[0113] The threshold is set to facilitate comparison. The threshold depends on the amount of sample data and the number of bases set by technicians in this field for each set of sample data.

[0114] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for detecting phthalates in electronic and electrical products, characterized in that: Step 1: Disassemble the electronic and electrical products and separate them into various single materials. Cut 1 mg with a cutting knife or tweezers, or crush and mix the samples evenly, and then press them into thin sheets or films with a tablet press for analysis; Step 2: Optimize the injection volume; Weigh 0.3 mg, 0.5 mg, 1.0 mg, 1.5 mg, and 2.0 mg of standard substance samples for verification. The thermal analysis conditions adopt the heating program: initial temperature 50 °C, increase to 300 °C at a rate of 150 °C / min, maintain for 1 min, carrier gas: nitrogen, injection time: 1 min; According to the test results, the sample with better test result stability and more stable sample recovery rate is selected as the weighing amount; Step 3: Optimize thermal analysis conditions; According to the physical properties of the boiling point of phthalates, the sample weight was selected as 1.0 mg, and the test was carried out at a gradient of thermal desorption temperatures of 250, 275, 300, 325, 350 and 370°C, and the optimal thermal desorption temperature was selected according to the results; Step 4: Selection of gas chromatography conditions, using two chromatographic columns for comparative verification; Step 5: Test the stability of retention time; Test the standard substance several times to determine whether the retention time is stable; Includes specific methods for testing retention time stability: A1: Test the standard substance multiple times and obtain the relative standard deviation value based on the retention time and the mean retention time of the standard substance; The standard substances include: DI BP, DBP, BBP, DEHP; The retention time of the standard substance is obtained by: A11: Test the standard substance multiple times to obtain the retention time of the standard substance and mark the retention time of the standard substance as T DIBP，n , T DBP，n , T BBP，n , T DEHP，n , where n is the number of different tests and n is a positive integer; The retention time mean value of the standard substance is obtained by: A12: Based on the obtained retention time of the standard substance, calculate the mean retention time of the standard substance and mark the mean retention time as The relative standard deviation value of group i is calculated as: A13: By formula: The relative standard deviation parameters are calculated and marked as D DIBP , D DBP , D BBP , D DEHP , select the maximum value of the relative standard deviation parameters of the standard substance as the relative standard deviation value of the current test, and mark the relative standard deviation value of the current test as DZ i ; A2: Repeat step A1 multiple times and change the number of tests to obtain multiple sets of relative standard deviation values ​​with different test times, and mark the relative standard deviation values ​​as DZ i , where i represents the i-th group test and i is a positive integer; A3: Obtain the mean value of the relative standard deviation; the method for obtaining the mean value of the relative standard deviation is: The obtained multiple groups of relative standard deviation values ​​are averaged to obtain the mean of the relative standard deviation values, and the mean of the relative standard deviation values ​​is marked as A4: Draw a relative standard deviation analysis chart and obtain the area of ​​the shaded region; The method for obtaining the area of ​​the shadow region is: Based on the X-DZ two-dimensional coordinate system, a relative standard deviation analysis chart is drawn for multiple sets of relative standard deviation values. In the chart, the X axis represents the number of tests, and the DZ axis represents the relative standard deviation value. Multiple sets of relative standard deviation values ​​are connected to obtain a broken line, and the broken line and The area enclosed by the straight line of the value is the shaded area, thereby obtaining the area of ​​the shaded area, and marking the area of ​​the shaded area as M; A5: Compare and analyze the areas of the shaded regions to determine whether the relative standard deviation values ​​obtained for multiple groups are stable; The method for determining whether the obtained multiple groups of relative standard deviation values ​​are stable is: The shadow area threshold is preset as MY, and the shadow area M is compared with the shadow area threshold MY for analysis; If M≤MY, the obtained multiple groups of relative standard deviation values ​​are determined to be stable, and the process goes to A6; If M>MY, it is determined that the multiple sets of relative standard deviation values ​​obtained are unstable and cannot be used as experimental data, so it is necessary to obtain multiple sets of relative standard deviation values ​​again; A6: Compare and analyze the mean values ​​of the relative standard deviations to determine whether the retention time is stable. The method for determining whether the retention time is stable is: The relative standard deviation threshold is preset as DY, and the relative standard deviation mean is Compare and analyze with the relative standard deviation value threshold DY; like The retention time is determined to be stable; like The retention time is determined to be unstable; A7: Analyze the relative standard deviation analysis chart to obtain the optimal number of tests; The method for obtaining the optimal number of tests is: Based on the relative standard deviation analysis chart, a fitting straight line is obtained according to multiple sets of relative standard deviation values, and the mean of the relative standard deviation values ​​is obtained according to the fitting straight line. The corresponding test times CS is rounded to obtain the optimal test times; Step 6: Method confirmation parameters, including: detection limit, precision and accuracy; Among them, accuracy is: calibration with standard substances, blank experiments and spike recovery experiments to evaluate the accuracy of the detection method; Step 7: Actual sample test spectrum; Materials including PVC, SBS, ABS, PE, rubber, and ink were selected for actual sample and spiked test. By comparing the chromatograms of the actual samples with those of the spiked samples, it was found that other compounds in the samples could be separated from the target compounds with good degree of separation. Step 8: Inter-laboratory comparison test; Several companies, research institutes and third-party testing agencies were selected to test PVC white, PVC, SBS, PE and rubber samples, and the accuracy of the content was determined based on the test data.

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