Method for screening and separating co-outflow isomeride and target detection object detection method

Abstract

The invention discloses a method for screening and separating co-outflow isomers and a target detection object detection method, the target detection object is 2, 3, 7, 8-chlorodioxin, quantitative detection of the target detection object is analyzed by using a high-resolution gas chromatography-high-resolution mass spectrometry, and the method comprises the following steps: S1: screening the isomers with co-outflow; s2, screening out co-efflux isomeride influencing the quantitative detection of the target detection substance; s3, setting conditions of a separation instrument for separating the co-outflow isomeride influencing the quantitative detection of the target detection substance; and S4, verifying the separation effect, and testing the mixed solution by adopting the separation instrument conditions to verify that the relative error between the actually measured mass concentration and the theoretical mass concentration of the target detection object is within a preset value. The accuracy of detecting the actually measured concentration of the target detection object by the high-resolution gas chromatography-high-resolution mass spectrometry is improved, and the influence of a co-outflow phenomenon on the toxic equivalent mass concentration of the sample is avoided.

Description

Technical Field

[0001] This application belongs to the field of pollutant detection technology, specifically involving methods for screening and separating co-eluent isomers and methods for detecting target analytes. Background Technology

[0002] In the field of pollutant detection, the detection of target analytes is often affected by various other compounds, leading to inaccurate detection of the target analytes, which has a great impact on environmental impact assessments and remediation. Specifically, as an example, dioxin compounds (PCDD / Fs) include two major classes of compounds: polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). There are 210 homologues of PCDD / Fs, of which 75 are PCDDs and 135 are PCDFs. Among them, 17 homologues (2,3,7,8-chloroPCDD / Fs) in which chlorine atoms are substituted at all four coplanar positions of 2, 3, 7, and 8 are more harmful to the human body. Among the 2,3,7,8-chloroPCDD / Fs, 2,3,7,8-tetrachlorodibenzodioxin (2,3,7,8-TCDD) is the most toxic compound known to humankind to date. Therefore, the detection of dioxins mainly focuses on the above-mentioned 17 2,3,7,8-chloroPCDD / Fs.

[0003] The toxicity of dioxins is evaluated using toxicity equivalents (TEQs). TEQ refers to the equivalent mass concentration of each dioxin analogue, converted to the equivalent mass concentration of 2,3,7,8-TCDD. The toxicity equivalent factor (TEF) is the ratio of the affinity of each dioxin analogue to 2,3,7,8-TCDD for the Ah receptor. The toxicity equivalent mass concentration is the product of the measured mass concentration and the toxicity equivalent factor of the isomer. Regarding toxicity equivalent mass concentrations, my country's "Standard for Pollution Control of Municipal Solid Waste Incineration" stipulates that the emission limit for dioxins in flue gas from municipal solid waste incinerators is 0.1 ng·TEQ / m³, with some regions further requiring an emission limit of 0.05 ng·TEQ / m³.

[0004] However, due to the large number of homologues of PCDD / Fs, in addition to octachloro-substituted PCDD / Fs, PCDD / Fs with the same number of chlorine atoms have varying numbers of isomers. Existing purification methods in dioxin detection technologies, such as silica gel sulfate, alumina columns, and activated carbon columns, are insufficient to separate the 17 2,3,7,8-chloro PCDD / Fs from their isomers. Furthermore, in existing technologies for dioxin detection, PCDD / Fs with the same number of chlorine atoms may co-elute, meaning that two or more compounds may have partially or completely overlapping chromatographic peaks due to their very similar chemical properties (such as structural composition and polarity), making them unable to be effectively separated by the chromatographic column. When 17 types of 2,3,7,8-chlorodioxins co-elute with some isomers, these co-elute isomers are called co-elute isomers. Because the chromatographic peaks between the co-elute isomers are not effectively separated, the quantitative accuracy of the 17 types of 2,3,7,8-chlorodioxins will be affected. This will result in some of the measured mass concentrations of 2,3,7,8-chlorodioxins being higher than expected, which in turn affects the TEQ value and the determination of whether the dioxin emission limit is exceeded. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this application provides a method for screening and separating co-eluting isomers and a method for detecting target analytes. By screening isomers that co-elut with the target analyte, the method quickly identifies co-eluting isomers that affect the quantitative detection of the target analyte. It also provides methods for setting separation instrument conditions and evaluating the separation effect from both qualitative and quantitative perspectives. In particular, it improves the accuracy of high-resolution gas chromatography-high-resolution mass spectrometry (GC-MS) for detecting 2,3,7,8-chlorodioxins, and has a certain degree of versatility. The target analyte can be other complex organic compounds with multiple isomers that are analyzed using GC-MS. The steps and methods of this application can be used to screen and separate co-eluting isomers that affect their quantitative analysis.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] A method for screening and separating co-eluting isomers that affect the quantitative detection of a target analyte, wherein the quantitative detection of the target analyte utilizes high-resolution gas chromatography-high-resolution mass spectrometry (HPLC-MS) for instrumental analysis, the method comprising:

[0008] S1: Screening isomers with co-eluenting includes: determining the instrument conditions for the target analyte and obtaining the peak elution time range of the target analyte; determining the instrument conditions for each non-target analyte and obtaining the peak elution time range of each non-target analyte; preliminarily screening isomers with overlapping peak shapes and co-eluenting based on the peak elution time range, and classifying them into groups of isomers with co-eluenting; the peak elution time range includes the peak start time, the peak time, and the peak end time;

[0009] S2: Screening out co-eluting isomers that affect the quantitative detection of the target analyte, including: preparing a mixed solution by mixing a non-target analyte single standard from the isomer group with the target analyte; analyzing the mixed solution based on the instrument conditions of the target analyte; and determining the co-eluting isomers that affect the quantitative detection of the target analyte based on the relative error between the measured mass concentration and the theoretical mass concentration of the target analyte.

[0010] S3: Set the separation instrument conditions for co-eluent isomers that affect the quantitative detection of target analytes;

[0011] S4: Verify the separation effect, including: using the separation instrument conditions to test the single standard of the co-eluting isomers that affect the quantitative detection of the target analyte, and determine the retention time and elution order of the co-eluting isomers that affect the quantitative detection of the target analyte; using the separation instrument conditions to test the target analyte to determine the retention time of the target analyte, and determine whether the chromatographic peak of the target analyte is separated from the chromatographic peak of the co-eluting isomers that affect the quantitative detection of the target analyte; if not separated, modify the separation instrument conditions; if separated, use the separation instrument conditions to test the mixed solution to verify that the relative error between the measured mass concentration and the theoretical mass concentration of the target analyte is within a preset value.

[0012] Furthermore, the target analyte is 2,3,7,8-chlorodioxin; the co-eluent isomer is an isomer that co-eluents with 2,3,7,8-chlorodioxin; and the co-eluent isomer that affects the quantitative detection of the target analyte is a non-2,3,7,8-chlorodioxin distributed between tetrachloro and heptachloro.

[0013] Furthermore, in step S1, the instrument conditions for the target analyte include: high-resolution gas chromatography with a DB-5MS column, 99.999% pure helium as the carrier gas, an inlet temperature of 270°C, splitless injection, and constant flow mode; a temperature program of initial temperature 140°C, holding for 1 min, increasing to 200°C at a rate of 20°C / min, holding for 1 min, increasing to 220°C at a rate of 5°C / min, holding for 16 min, increasing to 235°C at a rate of 5°C / min, holding for 7 min, increasing to 310°C at a rate of 5°C / min, and holding for 10 min; and high-resolution mass spectrometry with SIM scan mode, EI source, ion source temperature of 260°C, and resolution greater than 10000.

[0014] Furthermore, the instrument conditions for each non-target analyte are the same as those for the target analyte.

[0015] Furthermore, the instrument conditions for each non-target analyte are divided into tetrachloro, pentachloro, hexachloro, and heptachloro instrument conditions based on the different numbers of chlorine atom substitutions. The high-resolution gas chromatography settings for the tetrachloro, pentachloro, hexachloro, and heptachloro instrument conditions are: DB-SMS column, 99.999% pure helium as carrier gas, 270°C inlet temperature, splitless injection, and constant flow mode. The high-resolution mass spectrometry settings are: SIM scan mode, EI source, ion source temperature 260°C, and resolution greater than 10000.

[0016] Furthermore, the temperature rise program for the tetrachloro apparatus is as follows: initial temperature 140℃, hold for 1 min, then rise to 200℃ at a rate of 20℃ / min, hold for 1 min, then rise to 220℃ at a rate of 5℃ / min, hold for 16 min, then rise to 235℃ at a rate of 15℃ / min, hold for 9 min, then rise to 310℃ at a rate of 15℃ / min, and hold for 5 minutes;

[0017] The temperature rise program for the pentachloro apparatus is as follows: initial temperature 140℃, hold for 1 min, then rise to 200℃ at a rate of 20℃ / min, hold for 1 min, then rise to 220℃ at a rate of 5℃ / min, hold for 16 min, then rise to 235℃ at a rate of 5℃ / min, hold for 7 min, then rise to 290℃ at a rate of 5℃ / min, hold for 4 min, then rise to 310℃ at a rate of 20℃ / min, hold for 2 min.

[0018] The heating program for the hexachloro apparatus is as follows: initial temperature 140℃, hold for 1 min, then increase to 200℃ at a rate of 20℃ / min, hold for 1 min, then increase to 220℃ at a rate of 5℃ / min, hold for 16 min, then increase to 235℃ at a rate of 5℃ / min, hold for 7 min, then increase to 310℃ at a rate of 5℃ / min, and hold for 5 minutes.

[0019] The heating program for the heptachloro apparatus is as follows: initial temperature 140℃, hold for 1 min, then increase to 200℃ at a rate of 20℃ / min, hold for 1 min, then increase to 220℃ at a rate of 5℃ / min, hold for 16 min, then increase to 235℃ at a rate of 5℃ / min, hold for 7 min, then increase to 310℃ at a rate of 5℃ / min, and hold for 7 minutes.

[0020] Furthermore, the chromatographic column used in the separation instrument conditions is SP-2331; the temperature program is changed to an initial temperature of 120°C, held for 2 min, increased to 220°C at a rate of 50°C / min, held for 15 min, increased to 250°C at a rate of 1.5°C / min, increased to 260°C at a rate of 0.6°C / min, and held for 10 min.

[0021] Further, the preset value is 5%; determining whether the chromatographic peak of the target analyte is separated from the chromatographic peak of the co-eluting isomer that affects the quantitative detection of the target analyte includes calculating the resolution R value of the chromatographic peak. When the R value is greater than or equal to 1.5, the chromatographic peak of the target analyte is separated from the chromatographic peak of the co-eluting isomer that affects the quantitative detection of the target analyte; when the R value is less than 1.5, the chromatographic peak of the target analyte is not separated from the chromatographic peak of the co-eluting isomer that affects the quantitative detection of the target analyte.

[0022] Furthermore, in step S1, the elution time range of the target analyte and the elution time range of each non-target analyte are obtained based on the ion flow maps of the target analyte and each non-target analyte.

[0023] In addition, this application also provides a method for detecting a target analyte, which uses the separation instrument conditions in the method described above for screening and separating co-eluent isomers that affect the quantitative detection of the target analyte to detect the target analyte.

[0024] Compared with the prior art, this application has the following advantages:

[0025] It is simple to operate, easy to understand, and easy to promote;

[0026] It can comprehensively screen analytes, especially isomers of chlorodioxins that exhibit co-eluting phenomena, and establish co-eluting isomer groups. Through quantitative analysis, it can quickly identify and quantitatively detect 2,3,7,8-chlorodioxin compounds that are affected. Using the established co-eluting isomer groups, it can quickly identify co-eluting isomers that affect the quantitative detection of 2,3,7,8-chlorodioxins.

[0027] This application provides separation instrument conditions for co-eluting isomers that affect the quantitative detection of 2,3,7,8-chlorodioxins, and provides methods for evaluating the separation effect from both qualitative and quantitative perspectives. This improves the accuracy of high-resolution gas chromatography-high-resolution mass spectrometry for the detection of 2,3,7,8-chlorodioxins and avoids the influence of co-eluting on the toxicity equivalent mass concentration of the sample.

[0028] The screening and separation method provided in this application involves screening for co-eluting isomers, screening for co-eluting isomers that affect the quantitative detection of the target analyte, setting separation instrument conditions, verifying the separation effect, and detecting the target analyte using the separation instrument conditions. It has a certain degree of versatility, and the target analyte can be other complex organic compounds that have multiple isomers and are analyzed using high-resolution gas chromatography-high-resolution mass spectrometry. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of the application and, together with their description, serve to explain the application, but do not constitute an undue limitation of the application. In the drawings:

[0030] Figure 1 Here are flowcharts for methods S1-S4 of this application;

[0031] Figure 2 This is a flowchart of step S1 of this application;

[0032] Figure 3 This is a flowchart of step S2 of this application;

[0033] Figure 4 This is a flowchart of step S4 of this application;

[0034] Figure 5 The ion chromatogram of pentachlorodioxin in the mixed solution under instrumental conditions for the target analyte;

[0035] Figure 6 The ion chromatogram of the mixed solution under instrumental conditions for the target analyte is shown.

[0036] Figure 7The ion chromatogram of pentachlorodioxin in the mixed solution under the conditions of the separation instrument is shown.

[0037] Figure 8 This is an ion chromatogram of hexachlorodioxin in a mixed solution under separation instrument conditions. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0039] In the description of this application, it should be understood that the relationship between the method steps can be sequential or non-sequential, as long as it does not affect the overall technical effect, and therefore should not be construed as a limitation of this application. The following description of this application is merely a description of individual embodiments of the technical solution of this application; other embodiments are not shown in the following description, but this does not mean that this application excludes these other embodiments, nor is the technical solution of this application limited to the specific implementations described below, and the scope of protection of this application is not limited to the specific implementations described below. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0040] It should be noted that if the terms "first," "second," etc., appear in the specification, claims, and accompanying drawings of this application, such descriptions are only used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0041] In some embodiments, such as Figure 1 As shown, this application provides a method for screening and separating co-eluting isomers that affect the quantitative detection of a target analyte. The quantitative detection of the target analyte utilizes high-resolution gas chromatography-high-resolution mass spectrometry (HPLC-MS). Instrumental analysis is a technical term in this field. When analyzing a sample, pretreatment is required before instrumental analysis; this entire process can be called sample analysis. The latter, where only the pretreated sample is analyzed using an instrument, is called instrumental analysis. The set instrument parameters are called instrument conditions. The method includes:

[0042] S1: Screen for isomers that co-efferenterate, such as Figure 2 As shown, the process includes: S11 determining the instrument conditions for the target analyte and obtaining the peak elution time range of the target analyte; S12 determining the instrument conditions for each non-target analyte and obtaining the peak elution time range of each non-target analyte; S13 preliminarily screening isomers with overlapping peaks and co-eluting based on the peak elution time range, and classifying them into groups of isomers with co-eluting; the peak elution time range includes the peak start time, the peak time, and the peak end time.

[0043] S2: Screen for co-elution isomers that affect the quantitative detection of the target analyte, such as... Figure 3 As shown, the process includes: S21 preparing a mixed solution of a non-target analyte single standard and a target analyte from the isomer group; S22 determining the co-eluent isomers that affect the quantitative detection of the target analyte based on the relative error between the measured mass concentration and the theoretical mass concentration of the target analyte.

[0044] S3: Set the separation instrument conditions for co-eluent isomers that affect the quantitative detection of target analytes;

[0045] S4: Verify the separation effect, such as Figure 4 As shown, the process includes: S41 using the separation instrument conditions to test the single standard of the co-eluting isomers affecting the quantitative detection of the target analyte, and determining the retention time and elution order of the co-eluting isomers affecting the quantitative detection of the target analyte; S42 using the separation instrument conditions to test the target analyte to determine the retention time of the target analyte, and to determine whether the chromatographic peak of the target analyte is separated from the chromatographic peak of the co-eluting isomers affecting the quantitative detection of the target analyte; S43 if not separated, modifying the separation instrument conditions; S44 if separated, testing the mixed solution using the separation instrument conditions to verify that the relative error between the measured mass concentration and the theoretical mass concentration of the target analyte is within a preset value.

[0046] In some embodiments, this application also provides a method for detecting a target analyte, wherein the target analyte is detected using the separation instrument conditions described above in the method for screening and separating co-eluent isomers that affect the quantitative detection of the target analyte.

[0047] In some embodiments, this application may specifically apply to the screening and separation of co-eluting isomers that affect the quantification of 2,3,7,8-chlorodioxins, wherein the 17 2,3,7,8-chlorodioxins are: 2,3,7,8-tetrachlorodibenzo-dioxin (2,3,7,8-TCDD), 1,2,3,7,8-pentachlorodibenzo-dioxin (1,2,3,7,8-PeCDD), 1,2,3,4,7,8-hexachlorodibenzo-dioxin (1,2,3,4,7,8-HxCDD), 1,2,3,6,7,8-hexachlorodibenzo-dioxin 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9-HxCDD-hexachlorodibenzo-dioxin (1,2,3,7,8,9-HxCDD), 1,2,3,4,6,7,8-heptachlorodibenzo-dioxin (1,2,3,4,6,7,8-HpCDD), octachlorodibenzo-dioxin (OCDD), 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF), 1,2,3,7,8-pentachlorodibenzofuran (1,2,3,7,8-PeCDF) ), 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PeCDF), 1,2,3,4,7,8-hexachlorodibenzofuran (1,2,3,4,7,8-HxCDF), 1,2,3,6,7,8-hexachlorodibenzofuran (1,2,3,6,7,8-HxCDF), 1,2,3,7,8,9-hexachlorodibenzofuran (1,2,3,7,8,9-HxCDF), 2,3,4,6,7,8-hexachlorodibenzofuran (2,3,4,6,7,8-HxCDF) The target analytes are 1,2,3,4,6,7,8-heptachlorodibenzofuran (1,2,3,4,6,7,8-HpCDF), 1,2,3,4,7,8,9-heptachlorodibenzofuran (1,2,3,4,7,8,9-HpCDF), and octachlorodibenzofuran (OCDF). This application aims to screen for co-eluting isomers affecting the quantification of 2,3,7,8-chloro PCDD / Fs, distributed between tetrachloro and heptachloro non-2,3,7,8-chloro PCDD / Fs. In this application, 2,3,7,8-chlorodioxins are the target analytes. Specifically, the method for screening and separating co-eluting isomers affecting the quantification of 2,3,7,8-chlorodioxins utilizes high-resolution gas chromatography-high-resolution mass spectrometry (HPLC-MS) for instrumental analysis, including the following steps:

[0048] Isomers exhibiting co-efferentiation were screened as follows:

[0049] The instrument conditions and elution time ranges of 2,3,7,8-chlorodioxins were determined for analysis of tetrachloro-octachloro PCDD / Fs. The analysis was performed using EPA 1613 method PAR standard solution, which contains 17 2,3,7,8-chloro PCDD / Fs.

[0050] Determine the preparation method for non-2,3,7,8-chlorodioxin standard solutions. Specifically, use only one single standard containing only one non-2,3,7,8-chlorodioxin, and dilute any single standard with excessively high concentrations to a low concentration to avoid negative impacts on chromatography and mass spectrometry.

[0051] Determine the instrument conditions for single-standard analysis of non-2,3,7,8-chloro PCDD / Fs. Use the same instrument method conditions as for the target analyte 2,3,7,8-chlorodioxins, or, to shorten the instrument analysis time for a single sample, preferably use the same chromatographic column as the instrument method conditions for 2,3,7,8-chlorodioxins. However, based on different chlorine atom substitution numbers, establish instrument conditions corresponding to the chlorine atom substitution numbers. Classify the methods applicable to single-standard qualitative analysis of non-2,3,7,8-chloro PCDD / Fs into tetrachloro instrument conditions, pentachloro instrument conditions, hexachloro instrument conditions, and heptachloro instrument conditions.

[0052] Determine the elution time range of non-2, 3, 7, 8 chlorinated PCDD / Fs. Analyze known types and concentrations of non-2, 3, 7, 8 chlorinated PCDD / Fs as single standards. Based on the ion chromatogram of each single standard, determine the elution time range of each non-2, 3, 7, 8 chlorinated PCDD / Fs, including the peak start time, peak time, and peak end time.

[0053] Isomers with co-elution were classified into groups based on the elution start time, peak time, and elution end time of each compound's chromatographic peak. Co-elution isomers with overlapping peak shapes were initially screened based on the elution time range and classified into groups of isomers with co-elution.

[0054] The following are co-elution isomers that affect the quantitative detection of the target analyte:

[0055] Prepare a mixed solution for screening co-eluting isomers. A single standard for non-2,3,7,8-chlorodioxins included in the co-eluting isomer groups is prepared by mixing the EPA 1613 method CS3 standard solution with 17 naturally occurring 2,3,7,8-chlorodioxins. 13 C 12Labeled 1,2,3,4-TCDD, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 2,3,4,7,8-HxCDD, 1,2,3,6, 7,8-HxCDD,1,2,3,7,8,9-HxCDD,1,2,3,4,6,7,8-HpCDD,OCDD,2,3,7,8-TCDF,1,2, 3,7,8-PeCDF, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 1,2,3, 7,8,9-HxCDF, 2,3,4,6,7,8-HxCDF, 1,2,3,4,6,7,8-HpCDF, 1,2,3,4,7,8,9-HpCDF, 13 C 12 The marked PCDD / Fs are internal standards;

[0056] The specific compounds of 2,3,7,8-chlorodioxins affected by the quantitative detection were identified. The mixed solution was analyzed and quantified using the internal standard method. Based on the relative error between the measured and theoretical mass concentrations of 17 2,3,7,8-chlorodioxins, the specific compounds of 2,3,7,8-chlorodioxins affected by the quantitative detection were identified.

[0057] Identify the types of co-eluent isomers that affect the quantitative detection of the target analyte, and identify the types of co-eluent isomers that affect the quantitative detection based on the co-eluent isomer group to which the 2,3,7,8-chlorodioxin compounds affected by the quantitative detection belong.

[0058] Qualitative analysis of co-eluenting was conducted based on ion chromatograms of the affected 2,3,7,8-chlorodioxin compounds, to analyze the co-eluenting situation.

[0059] The separation instrument conditions for co-eluting isomers that affect the quantitative detection of target analytes are set as follows:

[0060] Separation experiments were conducted using a mixed solution;

[0061] A new gas chromatographic column and a new temperature program were used, and these conditions were those of the separation instrument.

[0062] The separation effect is verified as follows:

[0063] The retention times and elution order of co-elution isomers affecting the quantitative detection of 2,3,7,8-chlorodioxins were determined. Single standards of co-elution isomers affecting the quantitative detection of 2,3,7,8-chlorodioxins were tested using separation instrument conditions to determine their retention times and elution order.

[0064] Qualitatively assess the separation effect by analyzing the ion chromatograms of the affected 2,3,7,8-chlorodioxin compounds for quantitative detection, and calculating the resolution R value between the chromatographic peaks of the affected 2,3,7,8-chlorodioxin compounds and the chromatographic peaks of the co-eluting isomers. The separation effect is judged from the perspective of chromatographic peak separation. When the R value is greater than or equal to 1.5, baseline separation is achieved between chromatographic peaks.

[0065] The separation effect was quantitatively analyzed and verified. The mixed solution was analyzed using separation instrument conditions. The separation effect was judged based on the deviation between the measured mass concentration and the theoretical mass concentration of 17 2,3,7,8-chlorodioxins. If the relative error of the test results was within 5%, the quantitative results of 2,3,7,8-chlorodioxins were considered accurate. The separation effect of co-eluting isomers and affected 2,3,7,8-chlorodioxin compounds was verified from a quantitative perspective.

[0066] When preparing non-2,3,7,8-chlorodioxin standard working solutions, the solvent used for dilution must be the same as the mother liquor solvent. When the mother liquor solvent is toluene, the solvent used for dilution is toluene; when the mother liquor solvent is nonane, the solvent used for dilution is nonane. Both the non-2,3,7,8-chlorodioxin standard working solutions and the mixed solutions must be sealed and stored away from light after preparation to prevent the evaporation of organic solvents. When preparing the mixed solutions, concentrate to near dryness using a nitrogen evaporator, add nonane to make up to volume, and then perform instrumental analysis.

[0067] High-resolution mass spectrometry employs selected ion scanning mode (SIM), which can monitor characteristic ions (m / z) of PCDD / Fs with different chlorine atom substitutions. Each chlorination scan range includes characteristic ions of PCDD / Fs and characteristic ions of the reference substance. The tetrachloroseries scan range includes characteristic ions of tetrachlorofuran (303.9016, 305.8987, 315.9419, 317.9389) and characteristic ions of tetrachlorodioxins (319.8965, 321.8936, 327.8847, 3...). Characteristic ions for PFK include 31.9368, 333.9339, and 292.9825 and 342.9787; ions in the pentachlorination range include characteristic ions for pentachlorinated furans (339.8597, 341.8568, 351.9000, 353.8970), characteristic ions for pentachlorinated dioxins (355.8546, 357.8517, 367.8949, 369.8919), and characteristic ions for PFK (354.9792, 380.9755); ions in the hexachlorination range are hexachlorinated furans. Characteristic ions for heptachlorofurans are 373.8207, 375.8178, 385.8610, and 387.3580; characteristic ions for hexachlorodioxins are 389.8157, 391.8127, 401.8559, and 403.8530; and characteristic ions for PFK are 392.9760 and 430.9729. The heptachloro range includes characteristic ions for heptachlorofurans (407.7818, 409.7788, 417.8253, and 419.8220) and characteristic ions for heptachlorodioxins (423.7). Characteristic ions of PFK include 767, 425.7737, 435.8169, 437.8140, and 430.9729 and 442.9729; octachloro range scanning ions include characteristic ions of octachlorofuran 441.7428, 443.7398, 451.7960, 453.7830, characteristic ions of octachlorodioxin 457.7377, 459.7348, 469.7780, 471.7750, and characteristic ions of PFK 442.9729 and 492.9691.

[0068] When using the internal standard method for quantification 13 C 12 The labeled 1,2,3,4-TCDD and 1,2,3,7,8,9-HxCDD were used as internal standards for injection. 13 C 12Labeled 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 2,3,4,7,8-HxCDD, 1,2,3,6,7,8-HxCDD, 1,2, 3,4,6,7,8-HpCDD,OCDD,2,3,7,8-TCDF,1,2,3,7,8-PeCDF,2,3,4,7,8-PeCDF,1,2, 3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 1,2,3,7,8,9-HxCDF, 2,3,4,6,7,8-HxCDF, 1,2,3,4,6,7,8-HpCDF and 1,2,3,4,7,8,9-HpCDF were used as internal standards for extraction, and 17 2,3,7,8-chloroPCDD / Fs were used as target analytes.

[0069] The following are the standards, reagents, and column models used in this application: commercially available non-2,3,7,8-chlorodioxin standard solutions (specific types and concentrations are shown in Table 1), EPA1613 method PAR standard solutions, EPA1613 method CS1-CS5, PFK, toluene, nonane, DB-5MS column, and SP-2331 column.

[0070] Table 1: Commercially available standard solutions of PCDD / Fs without 2, 3, 7, or 8-position chlorination

[0071]

[0072]

[0073] In some embodiments, this application uses high-resolution gas chromatography-high-resolution mass spectrometry for analysis and detection, as detailed below:

[0074] Isomers exhibiting co-efferentiation were screened as follows:

[0075] The instrument conditions and peak time ranges for 17 2,3,7,8-chlorodioxins were determined. PAR standard solutions from the EPA 1613 method were used for analysis. The instrument conditions were as follows: high-resolution gas chromatography settings: DB-5MS column, 99.999% pure helium as carrier gas, inlet temperature 270℃, splitless injection, constant flow mode, temperature program: initial temperature 140℃, hold for 1 min, then increase to 200℃ at a rate of 20℃ / min, hold for 1 min, then increase to 220℃ at a rate of 5℃ / min, hold for 16 min, then increase to 235℃ at a rate of 5℃ / min, hold for 7 min, then increase at a rate of 5℃ / min... The temperature was rapidly increased to 310℃ and held for 10 minutes. High-resolution mass spectrometry settings: SIM scan mode, EI source, ion source temperature 260℃, resolution greater than 10000. Tetrachloro ions (m / z) were 303.9016, 305.8987, 315.9419, 317.9389, 319.8965, 321.8936, 327.8847, 331.9368, 333.9339, 292.9825, and 342.9787. Pentylchloro ions (m / z) were 339.8597, 3... The hexachloro ions (m / z) were 41.8568, 351.9000, 353.8970, 355.8546, 357.8517, 367.8949, 369.8919, 354.9792, and 380.9755, respectively. The hexachloro ions (m / z) were 373.8207, 375.8178, 385.8610, 387.3580, 389.8157, 391.8127, 401.8559, 403.8530, 392.9760, and 430.9729, respectively. The heptachloro ions (m / z) were also included. The m / z values ​​were 407.7818, 409.7788, 417.8253, 419.8220, 423.7767, 425.7737, 435.8169, 437.8140, 430.9729, and 442.9729, respectively. The m / z values ​​for the octachloro ions were 441.7428, 443.7398, 451.7860, 453.7830, 457.7377, 459.7348, 469.7780, 471.7750, 442.9729, and 492.9691. The retention times of the 17 2,3,7,8-chlorodioxins obtained under the above conditions are shown in the table below.

[0076] Table 2: Elution time range of 2,3,7,8-chlorodioxins (elution start time - peak time - elution end time)

[0077]

[0078]

[0079] To determine the preparation method for non-2,3,7,8-chlorodioxin standard working solutions, based on the concentrations of non-2,3,7,8-chloroPCDD / Fs involved in Table 1, to avoid the influence of high concentrations, the 50 μg / mL and 5 μg / mL compound standard solutions need to be diluted to a low concentration. For the 50 μg / mL and 5 μg / mL standard solutions, dilute to a concentration of 50 ng / mL. For the 25 ng / mL standard solution, it can be directly used as the standard working solution after opening and aliquoting. After opening and aliquoting or preparation, the standard working solutions should be thoroughly mixed, sealed, and stored away from light.

[0080] The instrument conditions for non-2,3,7,8-chlorodioxins were determined using the same chromatographic column as those for 17 2,3,7,8-chlorodioxins. Based on the number of chlorine atoms substituted, instrument conditions were categorized into tetrachloro, pentachloro, hexachloro, and heptachloro conditions. The general settings for all instrument conditions were: column model DB-5MS, carrier gas 99.999% pure helium, inlet temperature 270℃, splitless injection, constant flow mode, and high-resolution mass spectrometer parameters set as follows: SIM scan mode, EI source, ion source temperature 260℃, resolution greater than 10000, using PFK as the reference material. The differentiated settings for each instrument method are shown in Table 3.

[0081] Table 3: Instrument conditions for single-standard PCDD / Fs without 2, 3, 7, and 8-position chlorination

[0082]

[0083]

[0084] The peak time ranges of non-2, 3, 7, 8-position chlorinated PCDD / Fs were determined. Single-standard analysis was performed on known types and concentrations of non-2, 3, 7, 8-position chlorinated PCDD / Fs. Based on the ion chromatograms of each single standard, the peak time ranges of each non-2, 3, 7, 8-position chlorinated PCDD / Fs were determined.

[0085] By classifying isomers that co-elute, based on the peak start time, peak time, and peak end time of the compounds, isomers that may have overlapping peak shapes can be preliminarily screened out and classified into co-elute isomer groups, as shown in Table 4 below.

[0086] Table 4: Groups of isomers with co-eluents and their elution time ranges (elution start time - peak time - elution end time)

[0087]

[0088]

[0089]

[0090] The following are co-elution isomers that affect the quantification of the target analyte:

[0091] Prepare a mixed solution for screening co-eluting isomers. Take the single standards for non-2, 3, 7, and 8-position chlorinated PCDD / Fs included in the co-eluting isomer groups in Table 4, and the EPA 1613 method CS3 standard solution to prepare mixed solution 1 for testing. Preparation of the mixed solution: Take 10 μL each of the standard working solution for non-2, 3, 7, and 8-position chlorinated PCDD / Fs from Table 4 and the EPA 1613 method CS3 standard solution, mix, and concentrate to near dryness using a nitrogen blower. Add 20 μL of nonane to make up to volume, mix well, and then test.

[0092] The specific compounds affected by the quantitative detection of 2,3,7,8-chloroPCDD / Fs were identified. The mixed solutions were tested under the instrument conditions for the target analytes, and the test results are summarized in Table 5. According to the relative errors between the measured and theoretical mass concentrations of the 17 2,3,7,8-chloroPCDD / Fs, the relative error of 2,3,4,7,8-PeCDF reached 54.34%, the relative error of 1,2,3,7,8,9-HxCDF reached 162.20%, and the relative errors of other compounds were all within 5%.

[0093] Table 5: Test results of 17 2,3,7,8-chloroPCDD / Fs obtained by testing the mixed solution under the instrument conditions of the target analyte.

[0094]

[0095]

[0096] The types of co-efferent isomers affecting quantitative analysis were determined. Based on the co-efferent isomer groups in Table 4, the co-efferent isomers of 2,3,4,7,8-PeCDF were identified as 2,3,4,6,7-PeCDF, 1,2,3,6,9-PeCDF, and 1,2,4,8,9-PeCDF. The co-efferent isomer of 1,2,3,7,8,9-HxCDF was identified as 1,2,3,4,8,9-HxCDF.

[0097] Qualitative analysis of co-outflow situation, analysis of appendages Figure 5 and Figure 6The ion chromatograms of 2,3,4,7,8-PeCDF and 1,2,3,7,8,9-HxCDF show that the peaks of 2,3,4,7,8-PeCDF and 1,2,4,8,9-PeCDF overlap into one peak, as do the peaks of 2,3,4,6,7-PeCDF and 1,2,3,6,9-PeCDF. Their retention times are extremely close, with partial peak overlap. The peaks of 1,2,3,4,8,9-HxCDF completely overlap with those of 1,2,3,7,8,9-HxCDF. The co-eluting isomers have significantly affected the quantitative accuracy of 2,3,4,7,8-PeCDF and 1,2,3,7,8,9-HxCDF.

[0098] The separation instrument conditions for co-eluting isomers that affect the quantitative detection of target analytes are set as follows:

[0099] Separation experiments were conducted using a mixed solution;

[0100] The conditions of high-resolution gas chromatography were changed. The column used was SP-2331. The temperature program was changed to an initial temperature of 120℃, hold for 2 min, increase to 220℃ at a rate of 50℃ / min, hold for 15 min, increase to 250℃ at a rate of 1.5℃ / min, increase to 260℃ at a rate of 0.6℃ / min, and hold for 10 min.

[0101] The separation effect is verified as follows:

[0102] The retention times and elution order of co-elution isomers affecting the quantification of 2,3,7,8-chloroPCDD / Fs were determined. Single standards of the co-elution isomers affecting the quantification of 2,3,7,8-chloroPCDD / Fs were tested using separation instrument conditions, namely 2,3,4,6,7-PeCDF, 1,2,3,6,9-PeCDF, 1,2,4,8,9-PeCDF, and 1,2,3,4,8,9-HxCDF. Among these, 2,3,4,6,7-PeCDF... The retention times of F, 1,2,3,6,9-PeCDF, and 1,2,4,8,9-PeCDF were 37.99 min, 39.26 min, and 43.16 min, respectively. The elution order from earliest to latest was 2,3,4,6,7-PeCDF, 1,2,3,6,9-PeCDF, and 1,2,4,8,9-PeCDF. The retention time of 1,2,3,4,8,9-HxCDF was 50.70 min. The retention times and elution order were determined.

[0103] Qualitatively assess the separation effect, based on the attached... Figure 7 and Figure 8The ion chromatograms of the affected 2,3,7,8-chloroPCDD / Fs compounds, namely 2,3,4,7,8-PeCDF and 1,2,3,7,8,9-HxCDF, were analyzed and quantified. The retention times of 1,2,3,6,9-PeCDF, 1,2,4,8,9-PeCDF, and 2,3,4,6,7-PeCDF were 37.99 min, 39.26 min, and 43.16 min, respectively; the retention time of 2,3,4,7,8-PeCDF was 41.96 min; and the retention times of 1,2,3,4,8,9-HxCDF and 1,2,3,7,8,9-HxCDF were 50.70 min and 52.27 min, respectively. It can be seen that the chromatographic peaks of 2, 3, 4, 7, 8-PeCDF and 1, 2, 3, 7, 8, 9-HxCDF have been completely separated from the co-eluent isomers. The resolution R values ​​of the chromatographic peaks were calculated and summarized in Table 6. It can be seen that the R values ​​are all greater than 1.5, indicating that the chromatographic peaks have achieved baseline separation and the peak shapes no longer interfere with each other. This can be qualitatively determined as separation.

[0104] Table 6: Resolution R values ​​of the co-eluting isomers after separation from 2,3,4,7,8-PeCDF and 1,2,3,7,8,9-HxCDF

[0105]

[0106]

[0107] Quantitative analysis and verification of the separation effect were performed using the separation instrument conditions. The mixed solution was analyzed, and the test results are summarized in Table 7. Compared with the instrument conditions for the target analytes, the relative error of the measured mass concentration of 2,3,4,7,8-PeCDF decreased from 54.34% to 2.92%, and the relative error of 1,2,3,7,8,9-HxCDF decreased from 162.20% to 1.01%. The measured mass concentrations of 17 2,3,7,8-chloroPCDD / Fs were compared with the theoretical values. The relative errors of the mass concentrations were all within 5%, which can be considered as accurate results. From a quantitative perspective, it was verified that the co-eluent isomers 2,3,4,6,7-PeCDF, 1,2,3,6,9-PeCDF, 1,2,4,8,9-PeCDF and 1,2,3,4,8,9-HxCDF no longer affect the quantification of 2,3,7,8-chloroPCDD / Fs, and the accuracy of quantification of 2,3,7,8-chloroPCDD / Fs was further improved.

[0108] Table 7: Test results of 17 2,3,7,8-chloroPCDD / Fs obtained by separating the mixed solution under the same instrument conditions.

[0109]

[0110]

[0111] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims. The selected and described embodiments are intended to best elucidate the principles of this application and its practical application, thereby enabling other those skilled in the art to best utilize this application with various modifications suitable for the contemplated specific purpose, as well as the various described embodiments.

Claims

1. A method of screening for separation of a co-eluting isomer that affects the quantitative detection of a target analyte, characterized by, The quantitative detection of the target detection object is performed by using high-resolution gas chromatography-high-resolution mass spectrometry, and the method comprises the following steps: S1: screening for co-eluted isomers, comprising: determining the instrument conditions of the target detection object and obtaining the peak time range of the target detection object; determining the instrument conditions of each non-target detection object and obtaining the peak time range of each non-target detection object; preliminarily screening the co-eluted isomers with overlapping peak shapes according to the peak time range, and dividing them into co-eluted isomer groups; the peak time range comprises the peak start time, the peak top time and the peak end time; S2: screening for co-eluted isomers affecting the quantitative detection of the target detection object, comprising: preparing a mixed solution by mixing the non-target detection object single standard in the isomer group with the target detection object; analyzing the mixed solution based on the instrument conditions of the target detection object, and determining the co-eluted isomers affecting the quantitative detection of the target detection object according to the relative error between the measured mass concentration and the theoretical mass concentration of the target detection object; S3: setting the separation instrument conditions for separating the co-eluted isomers affecting the quantitative detection of the target detection object; S4: verifying the separation effect, comprising: testing the single standard of the co-eluted isomers affecting the quantitative detection of the target detection object by using the separation instrument conditions, determining the retention time and elution order of the co-eluted isomers affecting the quantitative detection of the target detection object; testing the target detection object by using the separation instrument conditions to determine the retention time of the target detection object, and determining whether the chromatographic peak of the target detection object is separated from the chromatographic peak of the co-eluted isomers affecting the quantitative detection of the target detection object, if not, modifying the separation instrument conditions; if yes, testing the mixed solution by using the separation instrument conditions to verify that the relative error between the measured mass concentration and the theoretical mass concentration of the target detection object is within a preset value.

2. The method for screening and separating co-eluted isomers affecting the quantitative detection of a target detection object according to claim 1, wherein: the target detection object is 2,3,7,8-chlorinated dioxin; the co-eluted isomers are isomers co-eluted with the 2,3,7,8-chlorinated dioxin; and the co-eluted isomers affecting the quantitative detection of the target detection object are non-2,3,7,8-chlorinated dioxins distributed between four chlorinated dioxins and seven chlorinated dioxins.

3. The method for screening and separating co-eluted isomers affecting the quantitative detection of a target detection object according to claim 2, wherein: ​ The instrument condition of the target detection object in step S1 is set as follows: high resolution gas chromatography, column type DB-5MS, carrier gas is helium with a purity of 99.999%, front inlet temperature is 270 DEG C, no split injection, constant flow mode; temperature rising program is as follows: initial temperature is 140 DEG C, kept for 1 min, then raised to 200 DEG C at a speed of 20 DEG C / min, kept for 1 min, then raised to 220 DEG C at a speed of 5 DEG C / min, kept for 16 min, then raised to 235 DEG C at a speed of 5 DEG C / min, kept for 7 min, then raised to 310 DEG C at a speed of 5 DEG C / min, kept for 10 min; high resolution mass spectrometry is set as SIM scanning mode, EI source, ion source temperature is 260 DEG C, resolution is greater than 10000.

4. The method for screening and separating the co-elution isomers affecting quantitative detection of the target detection object according to claim 3, wherein the single standard instrument condition of each non-target detection object is the same as the instrument condition of the target detection object.

5. The method for screening and separating the co-elution isomers affecting quantitative detection of the target detection object according to claim 3, wherein the single standard instrument condition of each non-target detection object is divided into four-chlorinated instrument condition, five-chlorinated instrument condition, six-chlorinated instrument condition and seven-chlorinated instrument condition according to the number of chlorine atom substitutions; the high resolution gas chromatography in the four-chlorinated instrument condition, five-chlorinated instrument condition, six-chlorinated instrument condition and seven-chlorinated instrument condition is set as follows: column type DB-5MS, carrier gas is helium with a purity of 99.999%, front inlet temperature is 270 DEG C, no split injection, constant flow mode; high resolution mass spectrometry is set as SIM scanning mode, EI source, ion source temperature is 260 DEG C, resolution is greater than 10000.

6. The method for screening and separating the co-elution isomers affecting quantitative detection of the target detection object according to claim 5, wherein the temperature rising program of the four-chlorinated instrument condition is as follows: initial temperature is 140 DEG C, kept for 1 min, then raised to 200 DEG C at a speed of 20 DEG C / min, kept for 1 min, then raised to 220 DEG C at a speed of 5 DEG C / min, kept for 16 min, then raised to 235 DEG C at a speed of 15 DEG C / min, kept for 9 min, then raised to 310 DEG C at a speed of 15 DEG C / min, kept for 5 min; the temperature rising program of the five-chlorinated instrument condition is as follows: initial temperature is 140 DEG C, kept for 1 min, then raised to 200 DEG C at a speed of 20 DEG C / min, kept for 1 min, then raised to 220 DEG C at a speed of 5 DEG C / min, kept for 16 min, then raised to 235 DEG C at a speed of 5 DEG C / min, kept for 7 min, then raised to 290 DEG C at a speed of 5 DEG C / min, kept for 4 min, then raised to 310 DEG C at a speed of 20 DEG C / min, kept for 2 min; ​ ​ ​ The temperature program of the six chlorinated instrument conditions is: initial temperature 140℃, holding for 1min, then increasing to 200℃ at a rate of 20 / min℃, holding for 1min, then increasing to 220℃ at a rate of 5 / min℃, holding for 16min, then increasing to 235℃ at a rate of 5 / min℃, holding for 7min, then increasing to 310℃ at a rate of 5 / min℃, holding for 5min; The temperature program of the seven chlorinated instrument conditions is: initial temperature 140℃, holding for 1min, then increasing to 200℃ at a rate of 20 / min℃, holding for 1min, then increasing to 220℃ at a rate of 5 / min℃, holding for 16min, then increasing to 235℃ at a rate of 5 / min℃, holding for 7min, then increasing to 310℃ at a rate of 5 / min℃, holding for 7min.

7. The method of claim 5, wherein the method further comprises: determining whether the chromatographic peak of the target analyte is separated from the chromatographic peak of the co-eluting isomer affecting quantitative detection of the target analyte. The temperature program of the six chlorinated instrument conditions is: initial temperature 140℃, holding for 1min, then increasing to 200℃ at a rate of 20 / min℃, holding for 1min, then increasing to 220℃ at a rate of 5 / min℃, holding for 16min, then increasing to 235℃ at a rate of 5 / min℃, holding for 7min, then increasing to 310℃ at a rate of 5 / min℃, holding for 5min; 8. The method of claim 5, wherein the method further comprises: determining whether the chromatographic peak of the target analyte is separated from the chromatographic peak of the co-eluting isomer affecting quantitative detection of the target analyte.

9. The method of claim 8, wherein the method further comprises: determining the peak time range of the target analyte and the peak time range of each non-target analyte based on the ion chromatogram of the target analyte and each non-target analyte. The target analyte is detected by using the separation instrument conditions in the method of claim 1-9. ​ 10. A method for detecting a target, characterized in that: ​

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