Analysis method and application of bromine and chlorine mixed dioxin

Abstract

The invention provides an analysis method and application of bromine and chlorine mixed dioxin. The analysis method comprises the following steps: (1) optimizing an ion source, a chromatographic column, a heating program and a carrier gas flow velocity of analysis equipment in gas chromatography-tandem mass spectrometry; (2) respectively determining collision energy, a quantitative ion pair and a qualitative ion pair for each PXDD / Fs homologue by using the optimized ion source, chromatographic column, heating program and carrier gas flow velocity; (3) optimizing the temperature, the pressure and the sample size of a sample inlet of the analysis equipment; and (4) establishing a separation and analysis method of the bromine-chlorine mixed dioxin according to the detection conditions determined in the steps (1)-(3). (5) detecting a standard solution of the PXDD / Fs by using a separation analysis method of the bromine-chlorine mixed dioxin (PXDD / Fs), and establishing a standard curve according to a detection result; and (6) carrying out repeated determination for more than five times by using the lowest concentration solution of the standard curve, and taking 3 times of standard deviation as the detection limit (LOD) of PXDD / Fs.

Description

Technical Field

[0001] The invention relates to the field of environmental pollutant detection, and in particular to an analysis method and application of bromine-chlorine mixed dioxins. Background Art

[0002] It is known that bromine-chlorine mixed dioxins (hereinafter referred to as "PXDD / Fs") are unintentional byproducts of combustion and chemical processes, with similar toxicity to PCDD / Fs. Depending on the number and position of substitution of bromine and chlorine atoms on 1-8 substitution positions on dioxins, a total of 1550 PXDDs and 3050 PXDFs can be formed, which exist in environmental media at concentrations of one part per billion (ppb) or one part per trillion (ppt).

[0003] According to the toxicity of PCDD / Fs, PXDD / Fs substituted at 2,3,7,8 positions are the most toxic. There are 337 PXDDs substituted at 2,3,7,8 positions and 467 PXDFs substituted at 2,3,7,8 positions in total. Similar to PBDD / Fs, the main sources of PXDD / Fs are waste incineration and industrial thermal processes. Studies have shown that thermal degradation of PBDEs in the presence of chlorine sources will produce higher concentrations of PXDD / Fs. During the incineration of municipal waste, the emission concentration of PXDD / Fs is 1%-20% of the corresponding PCDD / Fs. Studies on flue gas emitted from different incineration and metal smelting have found different ratios of PXDD / Fs, PBDD / Fs and PCDD / Fs. In some processes, the concentration of PXDD / Fs is higher than that of PCDD / Fs. Although the environmental concentrations vary, PXDD / Fs and PCDD / Fs have the same environmental sources, indicating that they have similar formation mechanisms. Some recent studies have shown that PXDD / Fs may also be derived from biosynthesis. In industrial thermal processes, the variables that determine the formation of PXDD / PXDFs and their degree of halogenation include temperature, thermal treatment time, Br / Cl ratio, and the presence of metal catalysts.

[0004] At present, the research on the analytical methods of PCDD / Fs and PBDD / Fs is relatively extensive, but there is a lack of research on the analytical methods of PXDD / Fs. Compared with PCDD / Fs, PXDD / Fs has a lower concentration in the environment, a complex matrix, poor stability and is easily decomposed under ultraviolet light. Therefore, high-sensitivity precision instruments are required for accurate determination, and high-sensitivity precision instruments increase the detection cost of PXDD / Fs. In addition, there is no universal standard analytical method for PXDD / Fs. Summary of the invention

[0005] In view of at least one of the above-mentioned technical problems existing in the prior art, the present invention provides an analysis method and application of PXDD / Fs.

[0006] Specifically, the first aspect of the present invention provides an analysis method for PXDD / Fs, which comprises the following steps: (1) optimizing the ion source, chromatographic column, temperature program, and carrier gas flow rate of the analysis device in a gas chromatography-tandem mass spectrometer; (2) using the optimized ion source, chromatographic column, temperature program, and carrier gas flow rate, respectively determining the collision energy and the quantitative ion pair and the qualitative ion pair for various bromine-chlorine mixed dioxins; (3) optimizing the injection port temperature and pressure and the injection volume of the analysis device; (4) establishing a separation and analysis method for bromine-chlorine mixed dioxins according to the detection conditions determined by (1) to (3); (5) using the separation and analysis method for bromine-chlorine mixed dioxins to detect a standard solution of bromine-chlorine mixed dioxins, and establishing a standard curve according to the detection results; (6) performing repeated measurements more than 5 times with the lowest concentration solution of the standard curve, and taking 3 times the standard deviation as the LOD of bromine-chlorine mixed dioxins; and calculating the recovery rate by adding a mixed standard substance to a blank matrix.

[0007] In the above-mentioned analysis method of PXDD / Fs, in step (1), when optimizing the ion source, PXDD / Fs is tested using an EI source and an NCI source respectively, and the ion source is selected according to the test results.

[0008] In the above PXDD / Fs analysis method, the ion with the highest abundance in the test result is the molecular ion [M]. - The ion source at that time was taken as the optimized ion source.

[0009] In the above-mentioned analysis method of PXDD / Fs, in step (1), when optimizing the chromatographic column, PXDD / Fs is tested using different chromatographic columns, and the chromatographic column is selected according to the test results.

[0010] In the above-mentioned analysis method of PXDD / Fs, the different chromatographic columns refer to a plurality of chromatographic columns having different at least one of column length, inner diameter and membrane thickness.

[0011] In the above-mentioned analysis method of PXDD / Fs, PXDD / Fs is detected under different heating conditions, and the heating program is selected according to the detection results.

[0012] In the above analysis method of PXDD / Fs, PXDD / Fs is detected at different carrier gas flow rates, and the carrier gas flow rate is selected according to the detection results.

[0013] In the above-mentioned analysis method of PXDD / Fs, in step (2), the PXDD / Fs congeners are subjected to Q3Scan scanning using optimized detection conditions, and the two characteristic ions with the highest response are selected as parent ions for each PXDD / Fs.

[0014] In the above-mentioned analysis method of PXDD / Fs, product ion scanning is performed on 9 PXDD / Fs mixed standard solutions and internal standard solutions of the same concentration under a specified collision energy. Based on the product ion scanning results, the two ion pairs with the highest response and the corresponding collision energies are selected for each PXDD / Fs as the optimized quantitative ion pair and qualitative ion pair as well as the optimized collision energy.

[0015] In the above-mentioned PXDD / Fs analysis method, the collision energy of the product ion scan is 15 to 45 eV.

[0016] In the above analysis method of PXDD / Fs, PXDD / Fs is detected at different injection port temperatures, and the injection port temperature is selected according to the detection results.

[0017] In the above analysis method of PXDD / Fs, each PXDD / Fs congener of the same concentration is analyzed by MRM scanning at different injection port pressures, the obtained chromatogram is peak integrated, and the injection port pressure is selected according to the peak area.

[0018] In the above-mentioned PXDD / Fs analysis method, the PXDD / Fs congeners include: 7-B-23-CDD, 2-B-378-CDD, 2-B-1378-CDD, 23-B-78-CDD, 8-B-23-CDF, 3-B-278-CDF, 4-B-2378-CDF, 23-B-78-CDF, and 13-B-278-CDF.

[0019] PXDD / Fs includes two structures: PXDDs and PXDFs. The structural formula is as follows:

[0020]

[0021] In the above-mentioned PXDD / Fs analysis method, in step (5), 9 kinds of 50 μg / mL PXDD / Fs standard solutions are diluted step by step with nonane to prepare mixed standard solutions with concentrations of 1, 5, 20, 80, 200, 500, and 1000 ppb. Using the optimized PXDD / Fs separation and analysis method, 2 μL of samples are injected in order from low to high concentration using an automatic sampler, and the obtained chromatograms are integrated respectively. 13The peak area ratio of C-23B78CDD was used as the ordinate (y) and the concentration ratio was used as the abscissa (x) for linear regression analysis, and the standard curves of 9 PXDD / Fs were obtained.

[0022] A second aspect of the present invention provides an application of the above-mentioned PXDD / Fs analysis method in the detection of PXDD / Fs in thermally treated recycled copper fly ash.

[0023] Effects of the Invention

[0024] The present invention provides an instrumental analysis method for analyzing 9 kinds of PXDD / Fs based on GC-MS / MS. By comparing EI, NCI ion sources and chromatographic columns, the parameters such as the temperature rise program, carrier gas flow rate, injection port temperature, injection port pressure, etc. are optimized, and the detection sensitivity of the instrument to PXDD / Fs is improved. 14 kinds of PXDD / Fs congeners can be well separated under GC conditions. The linear range, LOD and recovery rate of PXDD / Fs are determined, and the correlation coefficients of the 9 kinds of PXDD / Fs are between 0.9987 and 0.9996, indicating that they have good linearity.

[0025] The application of the instrumental analysis method for PXDD / Fs provided by the present invention in the detection of PXDD / Fs in heat-treated recycled copper fly ash provides data support for understanding the emission characteristics of PXDD / Fs in the recycled copper smelting process and developing the reduction of PXDD / Fs in the recycled copper smelting process, and also provides valuable information for understanding the generation and transformation mechanism of PXDD / Fs in the recycled copper smelting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is a mass spectrum diagram showing the test results of 7B23CDD and 13B278CDF based on NCI source and EI source according to one embodiment of the present invention.

[0027] Figure 2 : is a graph showing the responses of nine types of PXDD / Fs according to one embodiment of the present invention at different heating rates.

[0028] Figure 3 Graph showing responses of nine types of PXDD / Fs at different carrier gas flow rates according to an embodiment of the present invention.

[0029] Figure 4 It is a diagram showing ion pairs and collision energy selection of nine types of PXDD / Fs according to one embodiment of the present invention.

[0030] Figure 5 Graph showing responses of nine types of PXDD / Fs at different injection port temperatures according to an embodiment of the present invention.

[0031] Figure 6 Graph showing responses of nine types of PXDD / Fs at different inlet pressures according to an embodiment of the present invention.

[0032] Figure 7 4 is a TIC diagram of nine types of PXDD / Fs according to an embodiment of the present invention.

[0033] Figure 8 This is a diagram showing the calibration curves of four types of PXDDs according to one embodiment of the present invention.

[0034] Fig. 9 This is a diagram showing the calibration curves of five types of PXDFs according to one embodiment of the present invention.

[0035] Fig.10 This is a graph showing the emission concentration of PXDD / Fs in the detected recycled copper fly ash samples according to one embodiment of the present invention.

[0036] Fig.11 : is a graph showing the emission concentrations of PXDDs and PXDFs in the detected recycled copper fly ash samples according to one embodiment of the present invention.

[0037] Fig.12 Schematic diagram showing the distribution characteristics of 9 types of PXDD / Fs congeners in the recycled copper fly ash sample detected according to one embodiment of the present invention.

[0038] Fig.13 This is a graph showing changes in the concentrations of four types of PXDDs detected at different heat treatment temperatures according to one embodiment of the present invention.

[0039] Fig.14 This is a graph showing changes in the concentrations of five types of PXDFs detected at different heat treatment temperatures according to one embodiment of the present invention. DETAILED DESCRIPTION

[0040] In this embodiment, the analysis method of PXDD / Fs comprises the following steps:

[0041] (1) In a gas chromatography-tandem mass spectrometry, the ion source, chromatographic column, temperature program, and carrier gas flow rate of the analysis device are optimized; (2) the collision energy, quantitative ion pair, and qualitative ion pair are determined for each bromochlorodioxin congener using the optimized ion source, chromatographic column, temperature program, and carrier gas flow rate; (3) the injection port temperature and pressure and injection volume of the analysis device are optimized; (4) a separation and analysis method for bromochlorodioxins is established according to the detection conditions determined by (1) to (3); (5) a standard solution of bromochlorodioxins is detected using the separation and analysis method for bromochlorodioxins, and a standard curve is established according to the detection results; (6) the lowest concentration solution of the standard curve is repeated for more than 5 times, and 3 times the standard deviation is used as the LOD of bromochlorodioxins; and the recovery rate is calculated by adding the mixed standard substance to the blank matrix.

[0042] (1) Optimization of ion source, chromatographic column, heating program and carrier gas flow rate

[0043] In this embodiment, the selection of the ion source, the selection of the chromatographic column, the temperature rise program, the carrier gas flow rate, etc. of the analysis equipment in the PXDD / Fs instrument analysis process are optimized.

[0044] It should be noted that the analysis equipment used in this embodiment is a gas chromatograph-mass spectrometer (GC-MS / MS) of Shimadzu Corporation, model TQ8040.

[0045] a. Selection of NCI and EI sources

[0046] In this embodiment, in order to enable the established method to achieve the highest sensitivity and accurate qualitative and quantitative information, the study used EI source and NCI source to analyze PXDD / Fs, and compared the results obtained by the two ion source analyses. Figure 1 The mass spectra of 7B23CDD and 13B278CDF were analyzed by two ion sources. Since the chemical structures of PXDD / Fs are similar, their fragmentation mechanisms are similar under the same ion source. In the case of NCI source analysis, the mass spectra of 9 PXDD / Fs are [Br] - It is the most abundant ion, accounting for more than 90%, and the second most abundant ion is [M-Br] - and [M] - , but the abundance of these two ions is lower than that of [Br] - Very low, almost non-existent, so when using NCI source to analyze PXDD / Fs, although its sensitivity will be improved, all fragment ions obtained by PXDD / Fs analysis are [Br] -, there are almost no characteristic ions or their intensity is very low, which leads to certain difficulties in the subsequent qualitative and quantitative analysis of compounds; Different from the NCI source, under the conditions of the EI source, the molecular ion [M] - It is the ion with the highest abundance. The molecular ions obtained using the EI source can be used as characteristic ions for subsequent qualitative and quantitative work, and MRM analysis can improve the sensitivity of the analysis. Therefore, the EI ion source is selected for the experimental method.

[0047] It should be noted that the specific names of the 9 PXDD / Fs involved in this embodiment are 7-B-23-CDD, 2-B-378-CDD, 2-B-1378-CDD, 23-B-78-CDD, 8-B-23-CDF, 3-B-278-CDF, 4-B-2378-CDF, 23-B-78-CDF, and 13-B-278-CDF.

[0048] PXDD / Fs includes two structures: PXDDs and PXDFs. The structural formula is as follows:

[0049]

[0050] b. Column Optimization

[0051] In this embodiment, since high temperature can easily break the carbon-bromine bond of PXDD / Fs during the analysis process, resulting in the decomposition of PXDD / Fs, using a shorter chromatographic column can reduce the decomposition loss of PXDD / Fs during the analysis process; PXDD / Fs has more than 4,000 isomers, and using a longer chromatographic column is helpful for the separation of the homologues of PXDD / Fs during the analysis process. Therefore, the study used DB-5MS (30m column length, 0.25mm inner diameter, 0.25μm film thickness, purchased from Agilent, USA) and DB-5HT (15m column length, 0.25mm inner diameter, 0.10μm film thickness, purchased from Agilent, USA) chromatographic columns to analyze PXDD / Fs standard solutions of the same concentration. Both columns can achieve good separation effects for the 9 types of PXDD / Fs in the mixed standard solution. However, when two columns were used to analyze the recycled copper samples separately, since the actual environmental samples contained not only the target 9 PXDD / Fs, the target PXDD / Fs and its isomers could not be separated when analyzing the 9 target PXDD / Fs using the 15m chromatographic column. When using the 30m chromatographic column, the separation effect of PXDD / Fs was much better than that of the 15m. Therefore, for the analysis of PXDD / Fs, the DB-5MS chromatographic column was finally used.

[0052] c. Selection of heating program

[0053] In this embodiment, since PXDD / Fs has too many homologues and similar structures, it is difficult to separate them. In order to better separate the target analytes and have the best response, the temperature program is optimized in this embodiment. Scan scanning is used, and other parameters are the same. The responses of 9 PXDD / Fs at heating rates of 3, 5, and 10°C / min are studied and compared. The injection concentration of all PXDD / Fs is 1ppm. The peak integration of the obtained chromatogram is performed, and the peak area is used as the basis for the response effect. Figure 2 As shown, the response of 4B2378CDF and 13B278CDF decreases from 3℃ / min to 5℃ / min, and increases from 5℃ / min to 10℃ / min. The response value of 10℃ / min is higher than that of 3℃ / min. The response of 2B378CDD increases from 3℃ / min to 5℃ / min, and increases from 5℃ / min to 10℃ / min. The response of 2B1378CDD decreased with the increase of the heating rate, and the response was highest at a heating rate of 5℃ / min. The response of 2B1378CDD gradually increased with the increase of the heating rate, and the response was highest at a heating rate of 10℃ / min. The peak areas of the other five PXDD / Fs showed an overall downward trend with the increase of the heating rate. Considering that the highly halogen-substituted PXDD / Fs is more susceptible to thermal decomposition during the analysis, the method mainly selects the heating rate with the highest response of the highly halogen-substituted PXDD / Fs, i.e., 10℃ / min.

[0054] d. Selection of carrier gas flow rate

[0055] In this embodiment, the response of 9 PXDD / Fs was compared with the carrier gas flow rate of 0.9mL / min, 1mL / min, 1.1mL / min, and 1.2mL / min. Scan analysis, other parameters are the same, 9 PXDD / Fs mixed standard samples are analyzed with carrier gas flow rates of 0.9mL / min, 1mL / min, 1.1mL / min, and 1.2mL / min, respectively, all PXDD / Fs injection concentration is 1ppm, the obtained chromatogram is peak integrated, and the peak area is used as the basis of the response effect, such as Figure 3 As shown in the figure, the response of 2B1378CDD gradually increases with the increase of carrier gas flow rate, and the response is highest at a carrier gas flow rate of 1.1 mL / min. The responses of the other 8 PXDD / Fs all show a gradually increasing trend with the increase of carrier gas flow rate, and the response is best at a carrier gas flow rate of 1.2 mL / min. Therefore, the method finally selects a carrier gas flow rate of 1.2 mL / min.

[0056] (2) Selection of parent ions, daughter ions, and collision energy

[0057] In this embodiment, the 9 PXDD / Fs were subjected to Q3Scan scanning using optimized parameters such as the ion source, chromatographic column, temperature program, and carrier gas flow rate, and the mass spectra obtained were observed. For each PXDD / Fs, the two characteristic ions with the highest response were selected as its parent ions, such as Figure 1 As shown in FIG. 1 , two ions with m / z of 330 (M-2) and 332 (M) are used as parent ions of 7B23CDD. At a collision energy of 15 to 45 eV, product ion scans were performed on nine PXDD / Fs standard solutions of the same concentration to optimize the collision energy, as shown in FIG. Figure 4 ,According to the product ion scanning results, the two ion pairs with the highest response and the corresponding collision energy were selected for each PXDD / Fs, and the MRM analysis methods of 9 PXDD / Fs were established as quantitative ion pairs and qualitative ion pairs, as shown in Table 1. In order to separate 23B78CDD and M23B78CDD, different ion pairs were selected for monitoring of the two compounds.

[0058] Table 1

[0059]

[0060]

[0061] (3) Optimization of injection port temperature, pressure, and injection volume

[0062] a. Selection of injection port temperature

[0063] In this embodiment, considering the need to completely vaporize PXDD / Fs and its easy decomposition by heat, the injection port temperature is set at 250-270°C in this embodiment. The study compared the instrument responses to 9 types of PXDD / Fs when the injection port temperature was 250, 260 and 270°C. Other parameters were the same, and the 9 types of PXDD / Fs used injection port temperatures of 250, 260, and 270°C, respectively. MRM scanning analysis was performed, and the injection concentration of all PXDD / Fs was 200ppb. The obtained chromatograms were peak integrated, and the peak area was used as the basis for the response effect. Figure 5 As shown, the injection temperature has little effect on the response of the nine PXDD / Fs. The peak areas tend to be consistent at three different injection temperatures. At 270°C, the response of highly halogen-substituted PXDD / Fs is better than that at 250°C and 260°C. This is because the highly halogen-substituted PXDD / Fs vaporizes more completely at 270°C. Therefore, for the analysis of PXDD / Fs, the method ultimately selects an injection temperature of 270°C.

[0064] b. Selection of injection port pressure and injection volume

[0065] In this embodiment, PXDD / Fs is a trace pollutant in the environment, and the selection of splitless injection can effectively reduce the LOD of the target, so the method selects splitless injection. Under normal circumstances, the injection volume is often selected as 1μL. However, in view of the extremely low residual amount of the target analyzed in this study in the environmental sample, the injection volume is 2μL. The study compared the responses of 9 types of PXDD / Fs measured by high-pressure injection without high-pressure injection and with injection port pressures of 100, 200 and 250kPa. The other parameters were the same, and the 9 types of PXDD / Fs used injection port pressures of 0, 100, 200, and 250kPa, respectively, and MRM scanning analysis, and the injection concentration of the 9 types of PXDD / Fs was 200ppb. The obtained chromatogram was peak integrated, and the peak area was used as the basis for the response effect. As Figure 6 As shown in the figure, for the 9 types of PXDD / Fs, after a certain pressure is applied to the inlet, their responses are enhanced, and with the increase of the inlet pressure, the response generally shows an upward trend, that is, at an inlet pressure of 250 kPa, the responses of the 9 types of PXDD / Fs reach the strongest, so the method finally selects an inlet pressure of 250 kPa.

[0066] In this embodiment, by optimizing the parameters such as the ion source, chromatographic column, injection port temperature, injection port pressure, heating program, carrier gas flow rate, etc., a GC-MS / MS separation and analysis method for 9 kinds of PXDD / Fs was finally established. The analysis parameters are shown in Table 2. The 9 kinds of PXDD / Fs standard solutions were analyzed using the optimized parameters, and the obtained chromatograms are shown in Figure 7 As shown, all PXDD / Fs homologues can be separated from each other, the ones with fewer halogen atom substitutions are detected first, and the PXDD / Fs with the largest number of halogen atom substitutions are detected last. When the halogen substitution numbers are the same, the ones with more chlorine atom substitutions are detected first.

[0067] Table 2

[0068]

[0069] (4) Based on the detection conditions determined by (1) to (3), a separation and analysis method for PXDD / Fs was established.

[0070] (5) Establishment of standard curve

[0071] In this embodiment, 9 kinds of 50 μg / mL PXDD / Fs standard solutions were diluted step by step with nonane to prepare mixed standard solutions with concentrations of 1, 5, 20, 80, 200, 500, and 1000 ppb. Using the optimized PXDD / Fs separation and analysis method, 2 μL of samples were injected in order from low to high concentration using an automatic sampler, and the obtained GC-MS / MS chromatograms were integrated to compare PXDD / Fs with the internal standard.13 The peak area ratio of C-23B78CDD was used as the ordinate (y) and the concentration ratio was used as the abscissa (x) for linear regression analysis. The standard curves of the nine PXDD / Fs are shown in Figure 2. Figure 8 , Fig. 9 The regression equation, linear correlation coefficient, linear range and peak time of homologues are shown in Table 3. It can be seen that the correlation coefficients (R 2 ) can reach above 0.99, showing good linearity.

[0072] Table 3

[0073]

[0074] (6) Detection limit and recovery rate

[0075] In this embodiment, the lowest concentration solution of the standard curve is used for repeated determination for more than 5 times, and 3 times the standard deviation (s) is used as the LOD of PXDD / Fs. The LOD results of 9 kinds of PXDD / Fs are shown in Table 4. For the calculation of the recovery rate, the mixed standard substance is added to the blank matrix, and 2 concentration levels are added for each target pollutant. Weigh 10g of quartz sand sample, and add 4ng to each PXDD / Fs homologue; weigh 10g of quartz sand sample, and add 40ng to each PXDD / Fs homologue, add 320mL of toluene, extract and purify the spiked sample and analyze it by GC-MS / MS, and the spiked recovery is 48.03% to 109.23%. As shown in Table 4, according to the newly released "National Food Safety Standard - Determination of Toxic Equivalents of Dioxins and Their Analogues in Foods" GB 5009.205-2024 in 2024, when PCDD / Fs are determined by GC-MS / MS, the recovery rate of PCDD / Fs is required to be 40% to 140%. Therefore, the overall recovery rate of PXDD / Fs is better in this embodiment.

[0076] Table 4

[0077]

[0078] Application examples

[0079] Application example 1: Analysis of the generation characteristics of PXDD / Fs in raw ash

[0080] In the application example, during the recycled copper smelting process, the organic residual impurities in the raw materials provide a carbon source, which combines with the inorganic or organic bromine and chlorine elements in the raw materials to generate PXDD / Fs under the catalysis of transition metals. At the same time, the raw materials for recycled copper smelting mainly include electronic waste such as wires and cables. These electronic wastes usually contain high levels of brominated flame retardants (BFRs) such as PBDEs. Therefore, during the smelting process, there is a process of conversion of PBDEs to PXDD / Fs. The established GC-MS / MS method was used to analyze the content of PXDD / Fs in the dryer and blast furnace fly ash generated in the recycled copper smelting process. Fig.10 From the analysis results, it can be seen that the total amount of PXDD / Fs in dryer fly ash and blast furnace fly ash is 77.77pg / g and 21.55pg / g respectively. The content of PXDD / Fs in dryer fly ash is much higher than that in blast furnace fly ash. The content of PXDFs in both fly ashes is significantly higher than that of PXDDs. Fig.11 .

[0081] In the application example, in order to better understand the emission characteristics of PXDD / Fs in the secondary copper smelting process, the distribution characteristics of 9 PXDD / Fs homologues were studied and analyzed, such as Fig.12 . For dryer and blast furnace fly ashes, among the 9 PXDD / Fs analyzed, the PXDD / Fs homologues with the highest content were 4B2378CDF and 3B278CDF, accounting for 72.26% and 67.65% of the total of the 9 PXDD / Fs, which may be due to the large number of isomers of the two PXDD / Fs. The concentrations of 23B78CDD and 23B78CDF in dryer fly ash were 2.58pg / g and 5.73pg / g, respectively, and the concentrations of 23B78CDD and 23B78CDF in blower fly ash were both 0.99pg / g. PXDD / Fs containing four halogen atoms substituted at the 2,3,7,8 positions are more toxic than other dioxin homologues and should be taken seriously.

[0082] Application Example 2: Analysis of the Generation Characteristics of PXDD / Fs in Thermally Treated Regenerated Copper Fly Ash

[0083] In the application example, due to the similar structures of PXDD / Fs and PBDD / Fs, the thermochemical reaction simulation experiment of PXDD / Fs uses the same temperature generation section as PBDD / Fs. In air atmosphere, the blast furnace fly ash in the recycled copper smelting process was heat treated at 250, 350 and 450 ° C, and the heat treatment time was 60 minutes. The solid phase extract after heat treatment was used to extract the organic pollutants, and then the solid phase extract was mixed with the gas phase absorption liquid for subsequent purification and concentration. The established PXDD / Fs analysis method was used to analyze the content of 9 PXDD / Fs in the blast furnace fly ash after heat treatment. From the analysis results, it can be seen that the content of PXDD / Fs in blast furnace fly ash after heat treatment has increased significantly. After heat treatment at 250, 350, and 450℃, the concentrations of PXDD / Fs are 2789.70pg / g, 100.92pg / g, and 34.49pg / g, respectively, which are 1.6 to 129.4 times the total amount of PBDD / Fs in the original ash. The total amount of PXDD / Fs increases sharply at a heating temperature of 250℃, which is 129.4 times that of the original ash. The change trend of PBDD / Fs at different heat treatment temperatures is different. The concentration of PXDD / Fs has reached the highest at 250℃. At 350℃, the content of PXDD / Fs drops sharply compared with that at 250℃. At 350-450℃, the content of PXDD / Fs decreases slowly. Therefore, in industrial production, if the residence time of recycled copper fly ash at 250℃ can be avoided, the generation of PXDD / Ds will be significantly reduced. like Fig.11 It can be seen that the concentrations of PXDFs and PXDDs increased significantly after heat treatment of blast furnace fly ash. When the reaction temperature was 250℃, the concentration of PXDFs was 2481.79pg / g and the concentration of PXDDs was 307.91pg / g; when the reaction temperature was 350℃, the concentration of PXDFs was 83.15pg / g and the concentration of PXDDs was 17.75pg / g; when the reaction temperature was 450℃, the concentration of PXDFs was 20.97pg / g and the concentration of PXDDs was 13.52pg / g. The total concentration of PXDFs in blast furnace fly ash after heat treatment was higher than that of PXDDs, indicating that de novo synthesis is an important process for the generation of PXDD / Fs during heat treatment.

[0084] In the application example, Fig.12The concentration distribution of PXDD / Fs homologues in the raw ash is similar to that in the raw ash. The main PXDD / Fs homologues in the blast furnace fly ash after heat treatment at 250℃ are 4B2378CDF, 3B278CDF and 8B23CDF. The content of 4B2378CDF is much higher than that of the other two PXDD / Fs, with a concentration of 1722.4371 pg / g, accounting for 61.74% of the total PXDD / Fs concentration. In addition, 2B1378CDD, 2B378CDD and 13B27 The concentration of 8CDF also increased significantly. Different from the distribution of PXDD / Fs homologues at 250℃, the main PXDD / Fs homologues in blast furnace fly ash after heat treatment at 350℃ were 4B2378CDF and 23B78CDD, accounting for 75.88% of the total PXDD / Fs concentration. The concentration distribution of each PXDD / Fs homologue in blast furnace fly ash after heat treatment at 450℃ was relatively even, among which 4B2378CDF had the highest concentration, accounting for 20.70% of the total PXDD / Fs content.

[0085] In the application example, Fig.13 , Fig.14Figure 2 is a graph showing the concentration changes of PXDD / Fs homologues at different temperatures. It can be seen that the content of each PXDD / Fs homologue in the original ash is relatively low. For 4B2378CDF, 8B23CDF, 7B23CDD, 13B278CDD, 2B378CDD, 23B78CDF and 3B278CDF, their concentrations increased significantly after heat treatment at 250℃ compared with the original ash, and decreased significantly after heat treatment at 350℃ compared with the heat treatment at 250℃. The concentrations increased significantly after heat treatment at 450℃ compared with the heat treatment at 250℃. The concentration of PCDD / Fs after heat treatment at 350℃ gradually decreases or remains basically unchanged compared with that at 350℃. Therefore, for these 7 PXDD / Fs homologues, there may be a process of decomposition or transformation into other organic matter when the heat treatment temperatures are 350 and 450℃. From the fact that the concentration of PCDD / Fs is the highest after heat treatment at 350℃ and the similar structural properties and elemental composition of PXDD / Fs and PCDD / Fs, it can be inferred that at 350℃ and 450℃, there is a large amount of transformation process of PXDD / Fs into PCDD / Fs (transformation of Br and Cl atoms). For 2B1378CDD, its concentration increased significantly at 250℃, and after heat treatment at 350℃, its concentration decreased significantly compared with that at 250℃. After heat treatment at 450℃, its concentration gradually increased compared with that at 350℃. Therefore, it is speculated that at 350℃, there is a large amount of 2B1378CDD conversion to PCDD / Fs. When heat treated at 450℃, the synthesis rate of 2B1378CDD itself is higher than the conversion rate to PCDD / Fs, and there may be a new synthesis pathway. For 23B78 For CDD, its concentration increased significantly when heat treated at 250℃. However, its concentration also increased when heat treated at 350℃, and decreased when heat treated at 450℃. Therefore, it can be inferred that, unlike the other 8 PXDD / Fs homologues, its self-synthesis rate is greater than its decomposition or conversion to other compounds when heat treated at 350℃. This result may be due to its structure or the presence of its precursors in the recycled copper fly ash. In the study of the formation mechanism of PXDD / Fs in industrial thermal processes, studies have shown that the thermal degradation of PBDEs under chlorine source conditions is the main factor in the formation of PXDD / Fs. The factors that determine the formation and degree of halogenation of PXDD / Fs include temperature, heat treatment time, Br / Cl ratio and metal catalyst.

[0086] The present invention provides an instrumental analysis method for analyzing 9 kinds of PXDD / Fs based on GC-MS / MS. By comparing EI, NCI ion sources and chromatographic columns, and optimizing parameters such as temperature rise program, carrier gas flow rate, injection port temperature, injection port pressure, etc., the detection sensitivity of the instrument to PXDD / Fs is improved, and 14 kinds of PXDD / Fs congeners can be well separated under GC conditions. The linear range, LOD and recovery rate of PXDD / Fs are determined, and the correlation coefficients of the 9 kinds of PXDD / Fs are between 0.9987 and 0.9996, indicating that they have good linearity. In the embodiments of the present invention, the following reagents were used: n-hexane, toluene (pesticide grade, CNW Company), dichloromethane (pesticide grade, JTBaker Company, USA); PXDD / Fs standard substances: 7-B-23-CDD (48.5 μg / mL), 2-B-378-CDD (47.5 μg / mL), 2-B-1378-CDD (47.5 μg / mL), 23-B-78-CDD (50 μg / mL), 8-B-23-CDF (50 μg / mL), 3-B-278-CDF (50 μg / mL), 4-B-2378-CDF (50 μg / mL), 23-B-78-CDF (50 μg / mL), 13-B-278-CDF (50 μg / mL); internal standard: 13 C-23B78CDD (50 μg / mL). The above standard substances and internal standards were purchased from Wellington Las, Canada, with a specification of 1.2 mL.

[0087] Taking the dryer fly ash and blast furnace fly ash of a typical secondary copper smelter as the research objects, the emission characteristics of PXDD / Fs in the secondary copper smelting process and laboratory simulation of thermochemical reactions at different temperatures were studied. The study found that the total concentrations of PXDD / Fs in the dryer and blast furnace fly ashes produced by secondary copper smelting were 77.77pg / g and 21.55pg / g, respectively. After the blast furnace fly ash was subjected to thermochemical reaction at a temperature of 250-450℃ in an air atmosphere, the PXDD / Fs content in the fly ash produced by secondary copper smelting increased significantly, which was 1.6-129.4 times the total concentration of PXDD / Fs in the original ash. The research results show that the fly ash produced in the secondary copper smelting process is also an important generation and catalytic matrix of PXDD / Fs. In the fly ash samples of the recycled copper smelter and the fly ash after heat treatment at 250-450℃, 4B2378CDF is the main congener, especially after the fly ash is heat treated at 250℃, the concentration of 4B2378CDF accounts for 61.74% of the total concentration of 9 PXDD / Fs. The concentration of PXDFs in the recycled copper fly ash is higher than that of PXDDs before and after heat treatment, indicating that the carbon element on the surface of the recycled copper fly ash combines with bromine and chlorine elements to synthesize PXDD / Fs from scratch under the catalysis of transition metal copper in the thermochemical reaction. After heat treatment at 250-450℃, the concentrations of PXDFs and PXDDs in the recycled copper fly ash increased significantly. By comparing and analyzing the generation characteristics of PXDD / Fs in recycled copper fly ash and thermal reaction products, it is found that the concentration of most PXDD / Fs increases significantly at a heat treatment temperature of 250°C, decreases significantly at a heat treatment temperature of 350°C, and decreases little or remains basically unchanged at a heat treatment temperature of 450°C, indicating that during heat treatment at 350°C, there may be a process in which PXDD / Fs is transformed into other more stable compounds such as PCDD / Fs. In this embodiment, technical support is provided for the detection of PXDD / Fs. The research results provide data support for understanding the emission characteristics of PXDD / Fs in the recycled copper smelting process and developing emission reduction measures for PXDD / Fs in the recycled copper smelting process, and at the same time provide valuable information for understanding the generation and transformation mechanism of PXDD / Fs in the recycled copper smelting process.

[0088] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for analyzing bromine-chlorine mixed dioxins, characterized in that: The following steps are involved: (1) In gas chromatography-tandem mass spectrometry, optimize the ion source, chromatographic column, temperature program, and carrier gas flow rate of the analytical equipment; (2) Using the optimized ion source, chromatographic column, temperature program, and carrier gas flow rate, the collision energy and quantitative and qualitative ion pairs were determined for various bromine-chlorine mixed dioxins; (3) Optimizing the injection port temperature, pressure and injection volume of the analytical equipment; (4) Establish a separation and analysis method for mixed bromine and chlorine dioxins based on the detection conditions determined by (1) to (3); (5) using the separation and analysis method for bromine-chlorine mixed dioxins to detect a standard solution of bromine-chlorine mixed dioxins, and establishing a standard curve based on the detection results; (6) Repeat the determination for more than 5 times with the lowest concentration solution of the standard curve, and take 3 times the standard deviation as the method limit of detection (LOD) of bromine-chlorine mixed dioxins; calculate the recovery rate by adding the mixed standard substance to the blank matrix.

2. The method for analyzing bromine-chlorine mixed dioxins according to claim 1, characterized in that: In step (1), when optimizing the ion source, the bromine-chlorine mixed dioxins are tested using an EI source and an NCI source respectively, and the ion source is selected according to the test results.

3. The method for analyzing bromine-chlorine mixed dioxins according to claim 2, characterized in that: The ion with the highest abundance in the test result is the molecular ion [M]. - The ion source at that time was taken as the optimized ion source.

4. The method for analyzing bromine-chlorine mixed dioxins according to claim 1, characterized in that: In step (1), when optimizing the chromatographic column, different chromatographic columns are used to test bromine-chlorine mixed dioxins, and the chromatographic column is selected according to the test results.

5. The method for analyzing bromine-chlorine mixed dioxins according to claim 4, characterized in that: The different chromatographic columns refer to a plurality of chromatographic columns having different at least one of column length, inner diameter and membrane thickness.

6. The method for analyzing bromine-chlorine mixed dioxins according to any one of claims 1 to 5, characterized in that: In step (2), the various bromine-chlorine mixed dioxins are subjected to Q3Scan scanning using the optimized detection conditions, and the two characteristic ions with the highest response are selected as parent ions for each bromine-chlorine mixed dioxin.

7. The method for analyzing bromine-chlorine mixed dioxins according to claim 6, characterized in that: At the specified collision energy, product ion scanning was performed on various bromine-chloride mixed dioxin standard solutions of the same concentration. According to the product ion scanning results, the two ion pairs with the highest response and the corresponding collision energies were selected for each bromine-chloride mixed dioxin as the optimized quantitative ion pair and qualitative ion pair as well as the optimized collision energy.

8. The method for analyzing bromine-chlorine mixed dioxins according to claim 7, characterized in that: In the product ion scan, the predetermined collision energy is 15 to 45 eV.

9. The method for analyzing bromine-chlorine mixed dioxins according to claim 1, characterized in that: The bromine-chlorine mixed dioxin analogs include: 7-B-23-CDD, 2-B-378-CDD, 2-B-1378-CDD, 23-B-78-CDD, 8-B-23-CDF, 3-B-278-CDF, 4-B-2378-CDF, 23-B-78-CDF, and 13-B-278-CDF.

10. Application of an analytical method in the detection of bromine-chlorine mixed dioxins in thermally treated recycled copper fly ash, characterized in that: The analysis method is the analysis method for mixed bromine-chlorine dioxins according to any one of claims 1 to 9.

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