A method for determining total organic halogen based on activated carbon adsorption, pyrolysis, ion chromatography / high performance liquid chromatography-mass spectrometry

Abstract

The application discloses a method for determining total organic halogen based on activated carbon adsorption, pyrolysis and ion chromatography / high performance liquid chromatography-mass spectrometry, and belongs to the technical field of water quality analysis and detection. The method introduces a set of high-selectivity "chloramine oxidation-2,6-dimethyl phenol derivatization" reaction system. Firstly, bromide ions / iodide ions are oxidized into bromamine / iodonium acid by using chloramine. Then, 2,6-dimethyl phenol is added. The bromamine and the iodonium acid react with the 2,6-dimethyl phenol to generate single derivatives 4-bromo-2,6-dimethyl phenol and 4-iodo-2,6-dimethyl phenol, respectively. Then, specific detection and quantification are realized in the MRM mode by using HPLC-ESI-QqQ-MS. The method is a total organic halogen quantitative method which can provide key information of halogen form distribution, has high sensitivity and high selectivity, and meets the urgent needs of synchronous and accurate monitoring of total amount and risk component of pollutants in current water quality safety evaluation.

Description

Technical Field

[0001] This invention belongs to the field of water quality analysis and detection technology, specifically relating to a method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry. Background Technology

[0002] Total Organic Halogen (TOX) is a key comprehensive indicator for assessing water quality, especially the safety of drinking water disinfection. Its accurate quantification is a core step in evaluating drinking water safety and disinfection process risks. It represents the total amount of all halogenated organic disinfection byproducts in a water sample, and its concentration level directly relates to the cytotoxicity and genotoxicity of the water sample. Accurate TOX determination is of irreplaceable value for comprehensively assessing disinfection process risks, optimizing treatment procedures, and ensuring water quality safety.

[0003] Currently, the mainstream methods for measuring TOX mainly follow two technical routes, but both have significant limitations.

[0004] The first technical route is based on the international standard method (such as EPA Method 9020B, ISO 9562:2004) established on the principle of "activated carbon adsorption-high temperature combustion / microcoulometric titration". This method is mature and is currently the benchmark method. However, the fundamental drawback of this method lies in the non-specificity of its terminal detector and the single-dimensionality of the information provided. The microcoulometric detector can only respond to the total halogen current signal and cannot distinguish between different halogens such as chlorine (Cl), bromine (Br), and iodine (I). Given that the cytotoxicity and genotoxicity of brominated and iodinated disinfection byproducts are usually significantly higher than their chlorinated analogs, the method only provides total summation data and lacks information on halogen speciation, which severely limits the accurate assessment of the overall toxicity of water samples. In addition, this method has poor tolerance to complex matrices (such as high salinity and high organic content), and slight fluctuations in combustion conditions can easily lead to test errors.

[0005] The second technical approach is a direct injection screening and targeted quantification method based on chromatography-mass spectrometry (GC-MS). This type of technology (such as liquid chromatography-tandem mass spectrometry) can qualitatively identify and accurately quantify specific halogenated organic compounds in water samples, providing clear compound information. However, it faces core theoretical bottlenecks and application challenges when dealing with the indicator of "total organic halogens": First, it cannot achieve effective theoretical connection and accurate conversion with the "total" indicator. Due to the significant differences in response factors of different halogenated organic compounds in mass spectrometry detectors, and the existence of a large number of unknown or unstandardized halogenated compounds, simply summing the concentrations of a limited number of known compounds cannot accurately equate to the total organic halogen concentration in halogen molar amounts. Second, the direct detection sensitivity for trace components is insufficient. Many disinfection byproducts in disinfected drinking water are at trace concentrations in the ng / L range. Direct injection often results in excessively high detection limits and poor repeatability due to severe matrix inhibition effects, leading to missed detections or inaccurate quantification of low-concentration components. Therefore, although this technical approach can achieve precise analysis of specific compounds, it is difficult to meet the need for accurate and reliable detection of the macroscopic indicator of "total organic halogens".

[0006] In summary, there is an urgent need for a method that can accurately determine the total organic halogen content in water samples: one that can inherit and optimize the classical pretreatment techniques for enriching and quantifying organic halogens in water samples, ensuring the accuracy and stability of the determination of the "total organic halogen" index, and also achieve independent and accurate quantification of different halogen species (Cl, Br, I). Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry.

[0008] This invention deeply integrates and synergistically optimizes a mature activated carbon adsorption and high-temperature pyrolysis pretreatment process with highly sensitive and selective ion chromatography (IC) and high-performance liquid chromatography tandem negative electrospray ionization triple quadrupole mass spectrometry (HPLC-ESI-QqQ-MS). Its core technological innovation lies in achieving, for the first time, separate, independent, and high-precision quantification of total organic chlorine (TOCl), total organic bromine (TOBr), and total organic iodine (TOI) within a coherent and automated methodological framework. The specific technical approach is as follows: After the water sample is enriched by activated carbon and pyrolyzed at high temperature, the organic halogens are uniformly converted into hydrogen halides / halogen elemental gases; for chloride ions in the pyrolysis absorption liquid, a highly sensitive and selective ion chromatography method is used for direct determination; although the ion chromatography method can enhance the selectivity when analyzing bromide ions and iodide ions, the coexisting anions will interfere with the determination. Therefore, this invention innovatively introduces a highly selective "chloramine oxidation-2,6-dimethylphenol derivatization" reaction system. First, chloramine is used to oxidize bromide ions / iodide ions to bromamine / hypoiodic acid, respectively. Then, 2,6-dimethylphenol is added. Bromine and hypoiodic acid react with 2,6-dimethylphenol to produce single derivatives 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol, respectively. Then, HPLC-ESI-QqQ-MS is used in multiple reaction monitoring (MRM) mode to achieve specific detection and quantification.

[0009] This method not only fully retains the advantages of standard methods in sample pretreatment and quantitative halogen conversion, ensuring the reliability of total data, but also overcomes the inherent limitation of traditional microcoulometric methods in distinguishing halogen types, providing high-dimensional information including halogen speciation far exceeding existing technologies. This invention provides a more accurate and advanced technical tool for water quality safety assessment and disinfection process optimization, possessing both macroscopic total control and microscopic speciation analysis capabilities.

[0010] A method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry is specifically performed according to the following steps:

[0011] I. Adsorption by activated carbon columns:

[0012] Collect the water sample to be tested and place it in a centrifuge tube. Install the activated carbon column on the adsorption module. Pass the water sample to be tested through the activated carbon column at a certain flow rate. Then rinse the activated carbon column with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process is completed, remove the activated carbon column and dry it to obtain the adsorbed activated carbon column.

[0013] II. Pyrolysis:

[0014] The adsorbed activated carbon column was pyrolyzed in the combustion furnace of the total organic halogen analyzer with oxygen as the carrier gas. The resulting hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in an absorption bottle containing ultrapure water to obtain the absorption liquid.

[0015] III. Derivatization reaction:

[0016] The absorption solution was filtered through a 0.22 μm pore size filter membrane and placed in a centrifuge tube. Ultrapure water was added to the centrifuge tube, followed by chloramine solution. The reaction was carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added and the reaction was carried out in the dark. Finally, sodium arsenite solution was added to quench the residual chloramine. The solution was then filtered through a 0.22 μm pore size filter membrane to obtain the treated sample.

[0017] IV. Quantitative Analysis by Ion Chromatography:

[0018] (1) Plot the standard curve for organochlorine compounds:

[0019] ① Preparation of a series of 4-chlorophenol solutions: 4-chlorophenol was selected as the standard substance of organochlorine; a series of 4-chlorophenol solutions were prepared using ultrapure water, so that the concentration of 4-chlorophenol as chlorine was 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0020] ② Activated carbon column adsorption: A series of 4-chlorophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-chlorophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0021] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0022] ④ Plotting the standard curve of organochlorine: Detect a series of standard absorption solutions using an ion chromatograph to obtain a series of chloride ion peak areas; plot the standard curve of organochlorine with the concentration of 4-chlorophenol (calculated as chloride) on the x-axis and the corresponding chloride ion peak areas on the y-axis.

[0023] (2) Determine the total organic chlorine content in the water sample to be tested:

[0024] The absorbent obtained in step two is detected by ion chromatography to obtain the chloride ion peak area; the obtained chloride ion peak area is substituted into the standard curve of organic chlorine drawn above to calculate the chloride ion content in the water sample to be tested, which is the total organic chlorine content in the water sample to be tested.

[0025] V. Quantitative analysis using high performance liquid chromatography-mass spectrometry:

[0026] (1) Draw the standard curve for organic bromine;

[0027] ① Preparation of a series of 4-bromophenol solutions: 4-bromophenol was selected as the standard substance for organic bromine; a series of 4-bromophenol solutions were prepared using ultrapure water, with the concentrations of the 4-bromophenol solutions (calculated as bromine) being 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0028] ② Activated carbon column adsorption: A series of 4-bromophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-bromophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0029] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0030] ④ Derivatization reaction: A series of standard absorption solutions were filtered through a 0.22 μm pore size filter membrane and placed in 8 centrifuge tubes. Ultrapure water was added to each of the 8 centrifuge tubes, followed by chloramine solution. The reactions were carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added to each of the tubes and the reactions were carried out in the dark. Finally, sodium arsenite solution was added to each tube to quench the residual chloramine. The tubes were then filtered through a 0.22 μm pore size filter membrane to obtain a series of processed standard samples.

[0031] ⑤ Input the mass of the MRM characteristic ion pair of 4-bromo-2,6-dimethylphenol, i.e., the parent ion is 199 Da and the daughter ion is 79 Da. Use HPLC-ESI-QqQ-MS in MRM mode to determine the chromatograms of the above-processed standard samples by gradient elution to obtain a series of peak areas of 4-bromo-2,6-dimethylphenol. Plot the standard curve of organic bromine with the concentration of bromine in a series of 4-bromophenol solutions as the x-axis and the peak area of ​​the corresponding 4-bromo-2,6-dimethylphenol as the y-axis.

[0032] (2) Draw the standard curve for organic iodine;

[0033] ① Preparation of a series of 4-iodophenol solutions: 4-iodophenol was selected as the standard substance for organic iodine; a series of 4-iodophenol solutions were prepared using ultrapure water, with the concentrations of the 4-iodophenol solutions (calculated as iodine) being 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0034] ② Activated carbon column adsorption: A series of 4-iodophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-iodophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0035] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0036] ④ Derivatization reaction: A series of standard absorption solutions were filtered through a 0.22 μm pore size filter membrane and placed in 8 centrifuge tubes. Ultrapure water was added to each of the 8 centrifuge tubes, followed by chloramine solution. The reactions were carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added to each of the tubes and the reactions were carried out in the dark. Finally, sodium arsenite solution was added to each tube to quench the residual chloramine. The tubes were then filtered through a 0.22 μm pore size filter membrane to obtain a series of processed standard samples.

[0037] ⑤ Input the mass of the MRM characteristic ion pair of 4-iodo-2,6-dimethylphenol, i.e., the parent ion is 247 Da and the daughter ion is 127 Da. Use HPLC-ESI-QqQ-MS in MRM mode to determine the chromatograms of the above-processed standard samples by gradient elution to obtain a series of peak areas of 4-iodo-2,6-dimethylphenol. Plot the standard curve of organic bromine with the concentration of 4-iodophenol (calculated as iodine) as the x-axis and the peak area of ​​the corresponding 4-iodo-2,6-dimethylphenol as the y-axis.

[0038] (3) Determine the content of total organic bromine and total organic iodine in the water sample to be tested:

[0039] Input the masses of the MRM characteristic ion pairs of 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol, i.e., the masses of the parent ion and the daughter ion; that is, for 4-bromo-2,6-dimethylphenol: set the MRM parent ion to 199 Da and the daughter ion to 79 Da; for 4-iodo-2,6-dimethylphenol: set the MRM parent ion to 247 Da and the daughter ion to 127 Da; use HPLC-ESI-QqQ-MS in MRM mode to determine the two mass spectra of the processed sample obtained in step three by gradient elution; select 4-bromo-2,6-dimethylphenol and 4-iodo- The mass of the MRM characteristic ion pair of 2,6-dimethylphenol, i.e., the mass of the parent ion and the daughter ion, is used to determine whether the water sample contains 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol based on the peak elution time. If 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol are present, the measured peak areas are substituted into the standard curves for organic bromine and organic iodine respectively, and the concentrations of 4-bromophenol solution (as bromine) and 4-iodophenol (as iodine) in the water sample are calculated. These concentrations represent the total organic bromine and total organic iodine content in the water sample.

[0040] The beneficial effects of this invention are:

[0041] This invention provides a method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high-performance liquid chromatography-mass spectrometry (HPLC / HPLC-MS). This method successfully achieves independent and simultaneous determination of total organic chlorine (TOCl), total organic bromine (TOBr), and total organic iodine (TOI) in water samples, overcoming the limitation of traditional methods that can only detect the summation amount. This invention exhibits high detection sensitivity, significantly better than the detection limit of the traditional microcoulometric method. The method also demonstrates good reproducibility, exhibiting stable analytical performance in different water matrices (such as drinking water and surface water), proving its excellent resistance to matrix interference. In summary, this invention provides a quantitative method for total organic halogens that can provide key information on halogen speciation, combining high sensitivity and high selectivity, meeting the urgent need for simultaneous and accurate monitoring of total pollutant content and risk components in current water quality safety assessments. Attached Figure Description

[0042] Figure 1 This is a flowchart of the determination of total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry in this invention;

[0043] Figure 2 The standard curve of organochlorine was plotted in Example 1;

[0044] Figure 3 The standard curve of organic bromine was plotted in Example 1;

[0045] Figure 4 The standard curve for organic iodine was plotted in Example 1. Detailed Implementation

[0046] Specific Implementation Method 1: This implementation method is a method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry, specifically completed according to the following steps:

[0047] I. Adsorption by activated carbon columns:

[0048] Collect the water sample to be tested and place it in a centrifuge tube. Install the activated carbon column on the adsorption module. Pass the water sample to be tested through the activated carbon column at a certain flow rate. Then rinse the activated carbon column with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process is completed, remove the activated carbon column and dry it to obtain the adsorbed activated carbon column.

[0049] II. Pyrolysis:

[0050] The adsorbed activated carbon column was pyrolyzed in the combustion furnace of the total organic halogen analyzer with oxygen as the carrier gas. The resulting hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in an absorption bottle containing ultrapure water to obtain the absorption liquid.

[0051] III. Derivatization reaction:

[0052] The absorption solution was filtered through a 0.22 μm pore size filter membrane and placed in a centrifuge tube. Ultrapure water was added to the centrifuge tube, followed by chloramine solution. The reaction was carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added and the reaction was carried out in the dark. Finally, sodium arsenite solution was added to quench the residual chloramine. The solution was then filtered through a 0.22 μm pore size filter membrane to obtain the treated sample.

[0053] IV. Quantitative Analysis by Ion Chromatography:

[0054] (1) Plot the standard curve for organochlorine compounds:

[0055] ① Preparation of a series of 4-chlorophenol solutions: 4-chlorophenol was selected as the standard substance of organochlorine; a series of 4-chlorophenol solutions were prepared using ultrapure water, so that the concentration of 4-chlorophenol as chlorine was 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0056] ② Activated carbon column adsorption: A series of 4-chlorophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-chlorophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0057] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0058] ④ Plotting the standard curve of organochlorine: Detect a series of standard absorption solutions using an ion chromatograph to obtain a series of chloride ion peak areas; plot the standard curve of organochlorine with the concentration of 4-chlorophenol (calculated as chloride) on the x-axis and the corresponding chloride ion peak areas on the y-axis.

[0059] (2) Determine the total organic chlorine content in the water sample to be tested:

[0060] The absorbent obtained in step two is detected by ion chromatography to obtain the chloride ion peak area; the obtained chloride ion peak area is substituted into the standard curve of organic chlorine drawn above to calculate the chloride ion content in the water sample to be tested, which is the total organic chlorine content in the water sample to be tested.

[0061] V. Quantitative analysis using high performance liquid chromatography-mass spectrometry:

[0062] (1) Draw the standard curve for organic bromine;

[0063] ① Preparation of a series of 4-bromophenol solutions: 4-bromophenol was selected as the standard substance for organic bromine; a series of 4-bromophenol solutions were prepared using ultrapure water, with the concentrations of the 4-bromophenol solutions (calculated as bromine) being 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0064] ② Activated carbon column adsorption: A series of 4-bromophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-bromophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0065] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0066] ④ Derivatization reaction: A series of standard absorption solutions were filtered through a 0.22 μm pore size filter membrane and placed in 8 centrifuge tubes. Ultrapure water was added to each of the 8 centrifuge tubes, followed by chloramine solution. The reactions were carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added to each of the tubes and the reactions were carried out in the dark. Finally, sodium arsenite solution was added to each tube to quench the residual chloramine. The tubes were then filtered through a 0.22 μm pore size filter membrane to obtain a series of processed standard samples.

[0067] ⑤ Input the mass of the MRM characteristic ion pair of 4-bromo-2,6-dimethylphenol, i.e., the parent ion is 199 Da and the daughter ion is 79 Da. Use HPLC-ESI-QqQ-MS in MRM mode to determine the chromatograms of the above-processed standard samples by gradient elution to obtain a series of peak areas of 4-bromo-2,6-dimethylphenol. Plot the standard curve of organic bromine with the concentration of bromine in a series of 4-bromophenol solutions as the x-axis and the peak area of ​​the corresponding 4-bromo-2,6-dimethylphenol as the y-axis.

[0068] (2) Draw the standard curve for organic iodine;

[0069] ① Preparation of a series of 4-iodophenol solutions: 4-iodophenol was selected as the standard substance for organic iodine; a series of 4-iodophenol solutions were prepared using ultrapure water, with the concentrations of the 4-iodophenol solutions (calculated as iodine) being 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0070] ② Activated carbon column adsorption: A series of 4-iodophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-iodophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0071] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0072] ④ Derivatization reaction: A series of standard absorption solutions were filtered through a 0.22 μm pore size filter membrane and placed in 8 centrifuge tubes. Ultrapure water was added to each of the 8 centrifuge tubes, followed by chloramine solution. The reactions were carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added to each of the tubes and the reactions were carried out in the dark. Finally, sodium arsenite solution was added to each tube to quench the residual chloramine. The tubes were then filtered through a 0.22 μm pore size filter membrane to obtain a series of processed standard samples.

[0073] ⑤ Input the mass of the MRM characteristic ion pair of 4-iodo-2,6-dimethylphenol, i.e., the parent ion is 247 Da and the daughter ion is 127 Da. Use HPLC-ESI-QqQ-MS in MRM mode to determine the chromatograms of the above-processed standard samples by gradient elution to obtain a series of peak areas of 4-iodo-2,6-dimethylphenol. Plot the standard curve of organic bromine with the concentration of 4-iodophenol (calculated as iodine) as the x-axis and the peak area of ​​the corresponding 4-iodo-2,6-dimethylphenol as the y-axis.

[0074] (3) Determine the content of total organic bromine and total organic iodine in the water sample to be tested:

[0075] Input the masses of the MRM characteristic ion pairs of 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol, i.e., the masses of the parent ion and the daughter ion; that is, for 4-bromo-2,6-dimethylphenol: set the MRM parent ion to 199 Da and the daughter ion to 79 Da; for 4-iodo-2,6-dimethylphenol: set the MRM parent ion to 247 Da and the daughter ion to 127 Da; use HPLC-ESI-QqQ-MS in MRM mode to determine the two mass spectra of the processed sample obtained in step three by gradient elution; select 4-bromo-2,6-dimethylphenol and 4-iodo- The mass of the MRM characteristic ion pair of 2,6-dimethylphenol, i.e., the mass of the parent ion and the daughter ion, is used to determine whether the water sample contains 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol based on the peak elution time. If 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol are present, the measured peak areas are substituted into the standard curves for organic bromine and organic iodine respectively, and the concentrations of 4-bromophenol solution (as bromine) and 4-iodophenol (as iodine) in the water sample are calculated. These concentrations represent the total organic bromine and total organic iodine content in the water sample.

[0076] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the volumes of the water sample to be tested in step one, the series of 4-chlorophenol solutions in step four, the series of 4-bromophenol solutions in step five, and the series of 4-iodophenol solutions in step five are all 50 mL; the activated carbon columns mentioned in steps one, four, and five are pre-filled 18×6 mm columns, purchased from Jena Analytical Instruments Ltd. Other steps are the same as in Specific Implementation Method One.

[0077] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: the water sample to be tested in step one, the series of 4-chlorophenol solutions in step four, the series of 4-bromophenol solutions in step five, and the series of 4-iodophenol solutions in step five are each passed through an activated carbon column at a flow rate of 5 mL / min; the concentration of the nitric acid solution in steps one, four, and five is 10 mmol / L, and the concentration of the sodium nitrate solution is 10 mmol / L. Other steps are the same as in Specific Implementation Method One or Two.

[0078] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that the rinsing in steps one, four, and five is performed three times, using a total of 20 mL of nitric acid or sodium nitrate solution for the three rinsings. The other steps are the same as in Specific Implementation Methods One to Three.

[0079] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the purity of the oxygen mentioned in steps Two, Four, and Five is ≥99.9%; the pyrolysis temperature mentioned in steps Two, Four, and Five is 950 ℃, and the pyrolysis time is 10 min; the volume of the ultrapure water mentioned in steps Two, Four, and Five is 25 mL. Other steps are the same as in Specific Implementation Methods One to Four.

[0080] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the volume ratio of the filtered absorbent, ultrapure water, chloramine solution, 2,6-dimethylphenol solution, and sodium arsenite solution in steps three and five is 5 mL:4.4 mL:100 μL:400 μL:100 μL. The other steps are the same as in Specific Implementation Methods One to Five.

[0081] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in the following ways: the concentration of the chloramine solution in steps three and five is 20 mmol / L; the concentration of the 2,6-dimethylphenol solution in steps three and five is 50 mmol / L; the concentration of the sodium arsenite solution in steps three and five is 23 mmol / L; and the reaction time in the dark in steps three and five is 15 min to 20 min. The other steps are the same as in Specific Implementation Methods One to Six.

[0082] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One through Seven in that: the ion chromatograph used in step four is the IC6220 ion chromatograph from the WanYi IC6200 series, the chromatographic column used is a Dionex AS19 column (4 mm × 250 mm), the autosampler used is an AS3110 autosampler, and it is equipped with a conductivity detector; the analytical conditions of the ion chromatograph are as follows: the eluent is 18 mmol / L KOH isocratic elution, the eluent flow rate is 1 mL / min, the column temperature is 30℃, the suppressor current is 54 mA, and the injection volume is 500 µL. Other steps are the same as in Specific Implementation Methods One through Seven.

[0083] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: the mobile phase used in the gradient elution described in step five includes mobile phase I and mobile phase II, with a flow rate of 0.2 mL / min; mobile phase I is acetonitrile, and mobile phase II is a 0.1% (v / v) formic acid aqueous solution. The injection volume is 20 μL, and the sample is injected through the HPLC column at a flow rate of 0.2 mL / min. Within 0 min to 10 min, the volume fraction of mobile phase I remains at 5%; within 10 min to 20 min, the volume fraction of mobile phase I linearly increases from 5% to 95%; within 20 min to 30 min, the volume fraction of mobile phase I remains at 95%; and within 30.1 min to 40 min, the volume fraction of mobile phase I changes to 5%. Other steps are the same as in Specific Implementation Methods One to Eight.

[0084] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: the HPLC-ESI-QqQ-MS described in step five consists of an Agilent 1260 HPLC coupled with an ABSciex QTrap 5500 MS with a negative ESI source. The Agilent 1260 HPLC is equipped with a Waters Symmetry C18 column (3.0 × 100 mm, 2.5 µm particle size). The MS conditions are as follows: ion source voltage -4500 V; gas I and gas II are both 50 arbitrary units; curtain gas is 35 arbitrary units; ion source temperature is 550°C; declustering potential (DP) is -100 V; collision energy (CE) is -40 V; inlet potential (EP) is -10 V; collision cell outlet potential (CXP) is -15 V. Other steps are the same as in Specific Implementation Methods One to Nine.

[0085] The beneficial effects of the present invention are verified using the following embodiments:

[0086] Example 1: Plotting standard curves for organochlorine, organobromine, and organoiodine.

[0087] Specifically, it is done by following these steps:

[0088] I. Plotting the standard curve for organochlorine compounds:

[0089] ① Preparation of a series of 4-chlorophenol solutions: 4-chlorophenol was selected as the standard substance of organochlorine; a series of 4-chlorophenol solutions were prepared using ultrapure water, so that the concentration of 4-chlorophenol as chlorine was 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0090] ② Activated carbon column adsorption: A series of 4-chlorophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-chlorophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0091] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0092] ④. Plotting the standard curve for organochlorine compounds: Detect a series of standard absorption solutions using an ion chromatograph to obtain a series of chloride ion peak areas; plot the standard curve for organochlorine compounds with the concentration of 4-chlorophenol (calculated as chloride) on the x-axis and the corresponding chloride ion peak areas on the y-axis. (See...) Figure 2 As shown;

[0093] II. Plot the standard curve for organic bromine;

[0094] ① Preparation of a series of 4-bromophenol solutions: 4-bromophenol was selected as the standard substance for organic bromine; a series of 4-bromophenol solutions were prepared using ultrapure water, with the concentrations of the 4-bromophenol solutions (calculated as bromine) being 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0095] ② Activated carbon column adsorption: A series of 4-bromophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-bromophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0096] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0097] ④ Derivatization reaction: A series of standard absorption solutions were filtered through a 0.22 μm pore size filter membrane and placed in 8 centrifuge tubes. Ultrapure water was added to each of the 8 centrifuge tubes, followed by chloramine solution. The reactions were carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added to each of the tubes and the reactions were carried out in the dark. Finally, sodium arsenite solution was added to each tube to quench the residual chloramine. The tubes were then filtered through a 0.22 μm pore size filter membrane to obtain a series of processed standard samples.

[0098] ⑤ Input the MRM characteristic ion pair mass of 4-bromo-2,6-dimethylphenol, i.e., the parent ion is 199 Da and the daughter ion is 79 Da. Utilize HPLC-ESI-QqQ-MS in MRM mode to determine the chromatograms of the above-treated standard samples by gradient elution, obtaining a series of peak areas of 4-bromo-2,6-dimethylphenol. Plot an organic bromine standard curve with the concentration of bromine in a series of 4-bromophenol solutions as the x-axis and the corresponding peak area of ​​4-bromo-2,6-dimethylphenol as the y-axis. (See figure) Figure 3 As shown;

[0099] III. Plot the standard curve for organic iodine;

[0100] ① Preparation of a series of 4-iodophenol solutions: 4-iodophenol was selected as the standard substance for organic iodine; a series of 4-iodophenol solutions were prepared using ultrapure water, with the concentrations of the 4-iodophenol solutions (calculated as iodine) being 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively.

[0101] ② Activated carbon column adsorption: A series of 4-iodophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-iodophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption.

[0102] ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions.

[0103] ④ Derivatization reaction: A series of standard absorption solutions were filtered through a 0.22 μm pore size filter membrane and placed in 8 centrifuge tubes. Ultrapure water was added to each of the 8 centrifuge tubes, followed by chloramine solution. The reactions were carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added to each of the tubes and the reactions were carried out in the dark. Finally, sodium arsenite solution was added to each tube to quench the residual chloramine. The tubes were then filtered through a 0.22 μm pore size filter membrane to obtain a series of processed standard samples.

[0104] ⑤ Input the MRM characteristic ion pair mass of 4-iodo-2,6-dimethylphenol, i.e., the parent ion is 247 Da and the daughter ion is 127 Da. Utilize HPLC-ESI-QqQ-MS in MRM mode to determine the chromatograms of the above-treated standard samples by gradient elution, obtaining a series of peak areas of 4-iodo-2,6-dimethylphenol. Plot the standard curve of organic bromine with the concentration of 4-iodophenol (calculated as iodine) on the x-axis and the corresponding peak area of ​​4-iodo-2,6-dimethylphenol on the y-axis. (See...) Figure 4 As shown.

[0105] The volumes of the series of 4-chlorophenol solutions mentioned in step one, the series of 4-bromophenol solutions mentioned in step two, and the series of 4-iodophenol solutions mentioned in step three are all 50 mL.

[0106] The activated carbon columns mentioned in steps one, two and three are pre-filled 18×6 mm columns, purchased from Jena Analytical Instruments Ltd.

[0107] The series of 4-chlorophenol solutions mentioned in step one, the series of 4-bromophenol solutions mentioned in step two, and the series of 4-iodophenol solutions mentioned in step three are passed through an activated carbon column at a flow rate of 5 mL / min; the concentration of the nitric acid solution mentioned in steps one, two, and three is 10 mmol / L, and the concentration of the sodium nitrate solution is 10 mmol / L.

[0108] The rinsing process described in steps one, two, and three is performed three times, using a total of 20 mL of nitric acid or sodium nitrate solution for each rinse.

[0109] The purity of the oxygen mentioned in steps one, two, and three is ≥99.9%; the pyrolysis temperature mentioned in steps one, two, and three is 950 ℃, and the pyrolysis time is 10 min; the volume of the ultrapure water mentioned in steps one, two, and three is 25 mL.

[0110] The volume ratio of the filtered absorbent, ultrapure water, chloramine solution, 2,6-dimethylphenol solution and sodium arsenite solution mentioned in steps two and three is 5 mL:4.4 mL:100 μL:400 μL:100 μL;

[0111] The concentration of the chloramine solution mentioned in steps two and three is 20 mmol / L; the concentration of the 2,6-dimethylphenol solution mentioned in steps two and three is 50 mmol / L; the concentration of the sodium arsenite solution mentioned in steps two and three is 23 mmol / L; and the reaction time in the dark in steps two and three is 15 min to 20 min.

[0112] The ion chromatograph used in step two is the IC6220 ion chromatograph from the Wanyi IC6200 series. The chromatographic column used is a Dionex AS19 column (4 mm × 250 mm), and the autosampler used is an AS3110 autosampler equipped with a conductivity detector. The analytical conditions of the ion chromatograph are as follows: the eluent is 18 mmol / L KOH isocratic elution, the eluent flow rate is 1 mL / min, the column temperature is 30℃, the suppressor current is 54 mA, and the injection volume is 500 µL.

[0113] The gradient elution described in steps two and three uses mobile phases I and II, with a flow rate of 0.2 mL / min. Mobile phase I is acetonitrile, and mobile phase II is a 0.1% (v / v) formic acid aqueous solution. The injection volume is 20 μL, and the sample is injected through the HPLC column at a flow rate of 0.2 mL / min. Within 0-10 min, the volume fraction of mobile phase I remains at 5%. Within 10-20 min, the volume fraction of mobile phase I linearly increases from 5% to 95%. Within 20-30 min, the volume fraction of mobile phase I remains at 95%. Within 30.1-40 min, the volume fraction of mobile phase I returns to 5%.

[0114] The HPLC-ESI-QqQ-MS described in steps two and three consisted of an Agilent 1260 HPLC coupled with an ABSciex QTrap 5500 MS with a negative ESI source. The Agilent 1260 HPLC was equipped with a Waters Symmetry C18 column (3.0 × 100 mm, 2.5 µm particle size). The MS conditions were as follows: ion source voltage -4500 V; gas I and gas II were both 50 arbitrary units; curtain gas was 35 arbitrary units; ion source temperature was 550°C; declustering potential (DP) was -100 V; collision energy (CE) was -40 V; inlet potential (EP) was -10 V; and collision cell outlet potential (CXP) was -15 V.

[0115] The retention times, characteristic ion pairs, standard curve equations, and correlation coefficients of each target analyte are shown in Table 1.

[0116] Table 1

[0117]

[0118] In Example 1, the limits of detection for both total organic bromine and total organic iodine concentrations were 0.5 μg / L. The recoveries of this method in laboratory tap water for the detection of total organic bromine and total organic iodine were 96.3% and 93.7% (n=6), respectively, with relative standard deviations of 6.4% and 4.9% (n=6), confirming the applicability of this method in practical water matrices.

[0119] Example 2: Determination of chlorine using activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry

[0120] The total organic halogen content in the Songhua River water after disinfection was determined by the following steps:

[0121] I. Chlorine disinfection treatment of Songhua River water:

[0122] 500 mL of Songhua River water sample filtered through a 0.22 μm pore size membrane was added to an amber glass bottle (with a polytetrafluoroethylene cap) to ensure no headspace conditions; then sodium hypochlorite solution was added to the bottle to make the effective chlorine concentration in the system 5 mg / L (calculated as Cl2); after reacting for 24 hours, excess sodium thiosulfate was added to quench the residual chlorine.

[0123] II. Adsorption by activated carbon columns:

[0124] 50 mL of chlorine-disinfected Songhua River water sample was placed in a centrifuge tube. A pre-filled 18×6 mm activated carbon column (purchased from Jena Analytical Instruments Ltd.) was installed on the Jena APU 2 adsorption module. The water sample was passed through the activated carbon column at a flow rate of 5 mL / min. The activated carbon column was then rinsed with 10 mmol / L nitric acid / sodium nitrate solution to remove inorganic halides. The rinsing volume was 20 mL, and the rinsing was repeated three times. After the rinsing was completed, the activated carbon column was removed and dried.

[0125] III. Pyrolysis:

[0126] The activated carbon column was pyrolyzed in the combustion furnace of the Multi X2500 total organic halogen analyzer. The carrier gas was high-purity oxygen with a purity of ≥99.9%, the temperature was 950℃, and the time was 10 min. The gas was collected and timed from the moment the activated carbon column was placed into the combustion furnace. The generated hydrogen halide and halogen gases were then dried in a sulfuric acid tank. After that, the hydrogen halide and halogen gases were collected in an absorption bottle containing 25 mL of ultrapure water to obtain the absorption liquid.

[0127] IV. Derivatization reaction:

[0128] After filtering the absorption solution through a 0.22 μm pore size membrane, 5 mL of water sample was added to a 10 mL centrifuge tube, followed by 4.4 mL of ultrapure water (to ensure a final system volume of 10 mL, which can be adjusted according to the drug concentration). Then, 100 μL of 20 mmol / L chloramine solution was added to bring the chloramine concentration to 200 μmol / L, and the reaction was allowed to proceed in the dark for 15 min (chloramine solution should be freshly prepared and its concentration standardized before each use). Next, 400 μL of 50 mmol / L 2,6-dimethylphenol solution was added to bring the 2,6-dimethylphenol concentration to 2 mmol / L, and the reaction was allowed to proceed in the dark for 20 min. Finally, 100 μL of 23 mmol / L sodium arsenite solution was added to bring the sodium arsenite concentration to 230 μmol / L to quench residual chloramine. The treated sample was then filtered through a 0.22 μm pore size membrane for analysis to obtain the derivatized sample.

[0129] V. Quantitative Analysis:

[0130] ① Quantitative analysis by ion chromatography:

[0131] The total organochlorine sample (absorption solution) was detected by ion chromatography. The concentration of chloride ions in the absorption solution obtained in step three was detected by ion chromatography equipped with a Dionex AS19 column (4 mm × 250 mm) and a conductivity detector. The response value of the sample was obtained, and the concentration of chloride ions in the sample was calculated according to the standard curve of Example 1, thereby obtaining the concentration of total organochlorine in the sample. The ion chromatograph used was the IC6220 ion chromatograph of the Wanyi IC6200 series, the chromatographic column used was a Dionex AS19 column (4 mm × 250 mm), and the autosampler used was an AS3110 autosampler. The sample analysis conditions were as follows: the eluent was 18 mmol / L KOH isocratic elution, the eluent flow rate was 1 mL / min, the column temperature was 30℃, the suppressor current was 54 mA, and the injection volume was 500 µL.

[0132] ② Quantitative analysis using high performance liquid chromatography-mass spectrometry:

[0133] The total organic bromine and total organic iodine in the sample (after derivatization) were detected by high-performance liquid chromatography-mass spectrometry (HPLC-MS): The water sample after step four (after derivatization) was analyzed by HPLC-MS in tandem with a triple quadrupole mass spectrometer with a negative ESI source in MRM mode to determine the response values ​​of the two derivatization products, 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol. The concentrations of bromide and iodide ions in the sample were calculated using the standard curve from Example 1, thereby obtaining the concentrations of total organic bromine and total organic iodine in the sample. The instrument used was an Agilent 1260 HPLC tandem with an ABSciex QTrap 5500 MS with a negative ESI source. Two derivatized products were separated by gradient elution using an Agilent 1260 HPLC system equipped with a Waters Symmetry C18 column (3.0 × 100 mm, 2.5 µm particle size). The mobile phase consisted of acetonitrile (phase A) and formic acid aqueous solution (0.1%, v / v) (phase B). The injection volume was 20 μL, and the flow rate was 0.2 mL / min. For the first 10 minutes, the volume ratio of phase A was maintained at 5%. From 10 to 20 minutes, the volume ratio of the mobile phase linearly changed from 5%A to 95%A. Afterward, the mobile phase was maintained at 95%A for 10 minutes, and then switched to 5%A ​​at 30.1 minutes. From 30.1 to 40 minutes, the mobile phase was maintained at 5%A to reequilibrate. The mass spectrometry conditions were as follows: ion source voltage -4500 V; gas I and gas II were both 50 arbitrary units; curtain gas was 35 arbitrary units; source temperature was 550 °C; declustering potential (DP) was -100. V; Collision energy (CE) is -40 V; Inlet potential (EP) is -10 V; Collision unit outlet potential (CXP) is -15 V. After obtaining the peak area of ​​the derivative, the concentrations of total organic bromine and total organic iodine in the sample were calculated using a standard curve.

[0134] The test results of the Songhua River water after chlorine disinfection were obtained by following the method in Example 2: the concentration of total organic chlorine was 211.7 (±14.3) μg / L; the concentration of total organic bromine was 85.2 (±9.4) μg / L; and the concentration of total organic iodine was 22.6 (±3.3) μg / L.

Claims

1. A method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry, characterized in that... The method is specifically implemented according to the following steps: I. Adsorption by activated carbon columns: Collect the water sample to be tested and place it in a centrifuge tube. Install the activated carbon column on the adsorption module. Pass the water sample to be tested through the activated carbon column at a certain flow rate. Then rinse the activated carbon column with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process is completed, remove the activated carbon column and dry it to obtain the adsorbed activated carbon column. II. Pyrolysis: The adsorbed activated carbon column was pyrolyzed in the combustion furnace of the total organic halogen analyzer with oxygen as the carrier gas. The resulting hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in an absorption bottle containing ultrapure water to obtain the absorption liquid. III. Derivatization reaction: The absorption solution was filtered through a 0.22 μm pore size filter membrane and placed in a centrifuge tube. Ultrapure water was added to the centrifuge tube, followed by chloramine solution. The reaction was carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added and the reaction was carried out in the dark. Finally, sodium arsenite solution was added to quench the residual chloramine. The solution was then filtered through a 0.22 μm pore size filter membrane to obtain the treated sample. IV. Quantitative Analysis by Ion Chromatography: (1) Plot the standard curve for organochlorine compounds: ① Preparation of a series of 4-chlorophenol solutions: 4-chlorophenol was selected as the standard substance of organochlorine; a series of 4-chlorophenol solutions were prepared using ultrapure water, so that the concentration of 4-chlorophenol as chlorine was 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively. ② Activated carbon column adsorption: A series of 4-chlorophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-chlorophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption. ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions. ④ Plotting the standard curve of organochlorine: Detect a series of standard absorption solutions using an ion chromatograph to obtain a series of chloride ion peak areas; plot the standard curve of organochlorine with the concentration of 4-chlorophenol (calculated as chloride) on the x-axis and the corresponding chloride ion peak areas on the y-axis. (2) Determine the total organic chlorine content in the water sample to be tested: The absorbent obtained in step two is detected by ion chromatography to obtain the chloride ion peak area; the obtained chloride ion peak area is substituted into the standard curve of organic chlorine drawn above to calculate the chloride ion content in the water sample to be tested, which is the total organic chlorine content in the water sample to be tested. V. Quantitative analysis using high performance liquid chromatography-mass spectrometry: (1) Draw the standard curve for organic bromine; ① Preparation of a series of 4-bromophenol solutions: 4-bromophenol was selected as the standard substance for organic bromine; a series of 4-bromophenol solutions were prepared using ultrapure water, with the concentrations of the 4-bromophenol solutions (calculated as bromine) being 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively. ② Activated carbon column adsorption: A series of 4-bromophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-bromophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption. ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions. ④ Derivatization reaction: A series of standard absorption solutions were filtered through a 0.22 μm pore size filter membrane and placed in 8 centrifuge tubes. Ultrapure water was added to each of the 8 centrifuge tubes, followed by chloramine solution. The reactions were carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added to each of the tubes and the reactions were carried out in the dark. Finally, sodium arsenite solution was added to each tube to quench the residual chloramine. The tubes were then filtered through a 0.22 μm pore size filter membrane to obtain a series of processed standard samples. ⑤ Input the mass of the MRM characteristic ion pair of 4-bromo-2,6-dimethylphenol, i.e., the parent ion is 199 Da and the daughter ion is 79 Da. Use HPLC-ESI-QqQ-MS in MRM mode to determine the chromatograms of the above-processed standard samples by gradient elution to obtain a series of peak areas of 4-bromo-2,6-dimethylphenol. Plot the standard curve of organic bromine with the concentration of bromine in a series of 4-bromophenol solutions as the x-axis and the peak area of ​​the corresponding 4-bromo-2,6-dimethylphenol as the y-axis. (2) Draw the standard curve for organic iodine; ① Preparation of a series of 4-iodophenol solutions: 4-iodophenol was selected as the standard substance for organic iodine; a series of 4-iodophenol solutions were prepared using ultrapure water, with the concentrations of the 4-iodophenol solutions (calculated as iodine) being 0.5 μg / L, 1 μg / L, 2 μg / L, 5 μg / L, 7 μg / L, 10 μg / L, 20 μg / L, and 50 μg / L, respectively. ② Activated carbon column adsorption: A series of 4-iodophenol solutions were placed in centrifuge tubes, and eight activated carbon columns were installed on the adsorption module. A series of 4-iodophenol solutions were passed through the eight activated carbon columns at a certain flow rate. The activated carbon columns were then rinsed with nitric acid solution or sodium nitrate solution to remove inorganic halides. After the process, the activated carbon columns were removed and dried to obtain eight activated carbon columns after adsorption. ③ Pyrolysis: The eight adsorbed activated carbon columns were sequentially pyrolyzed in the combustion furnace of the total organic halogen analyzer. The carrier gas was oxygen. The generated hydrogen halide and halogen gas were then dried by a sulfuric acid dryer. After drying, the hydrogen halide and halogen gas were collected in eight absorption bottles containing ultrapure water to obtain a series of standard absorption solutions. ④ Derivatization reaction: A series of standard absorption solutions were filtered through a 0.22 μm pore size filter membrane and placed in 8 centrifuge tubes. Ultrapure water was added to each of the 8 centrifuge tubes, followed by chloramine solution. The reactions were carried out in the dark. After the reaction was completed, 2,6-dimethylphenol solution was added to each of the tubes and the reactions were carried out in the dark. Finally, sodium arsenite solution was added to each tube to quench the residual chloramine. The tubes were then filtered through a 0.22 μm pore size filter membrane to obtain a series of processed standard samples. ⑤ Input the mass of the MRM characteristic ion pair of 4-iodo-2,6-dimethylphenol, i.e., the parent ion is 247 Da and the daughter ion is 127 Da. Use HPLC-ESI-QqQ-MS in MRM mode to determine the chromatograms of the above-processed standard samples by gradient elution to obtain a series of peak areas of 4-iodo-2,6-dimethylphenol. Plot the standard curve of organic bromine with the concentration of 4-iodophenol (calculated as iodine) as the x-axis and the peak area of ​​the corresponding 4-iodo-2,6-dimethylphenol as the y-axis. (3) Determine the content of total organic bromine and total organic iodine in the water sample to be tested: Input the masses of the MRM characteristic ion pairs of 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol, i.e., the masses of the parent ion and the daughter ion; that is, for 4-bromo-2,6-dimethylphenol: set the MRM parent ion to 199 Da and the daughter ion to 79 Da; for 4-iodo-2,6-dimethylphenol: set the MRM parent ion to 247 Da and the daughter ion to 127 Da; use HPLC-ESI-QqQ-MS in MRM mode to determine the two mass spectra of the processed sample obtained in step three by gradient elution; select 4-bromo-2,6-dimethylphenol and 4-iodo- The mass of the MRM characteristic ion pair of 2,6-dimethylphenol, i.e., the mass of the parent ion and the daughter ion, is used to determine whether the water sample contains 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol based on the peak elution time. If 4-bromo-2,6-dimethylphenol and 4-iodo-2,6-dimethylphenol are present, the measured peak areas are substituted into the standard curves for organic bromine and organic iodine respectively, and the concentrations of 4-bromophenol solution (as bromine) and 4-iodophenol (as iodine) in the water sample are calculated. These concentrations represent the total organic bromine and total organic iodine content in the water sample.

2. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The volume of the water sample to be tested in step one, the series of 4-chlorophenol solutions in step four, the series of 4-bromophenol solutions in step five, and the series of 4-iodophenol solutions in step five are all 50 mL; the activated carbon columns mentioned in steps one, four, and five are pre-filled 18×6 mm columns, purchased from Jena Analytical Instruments Ltd.

3. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The water sample to be tested mentioned in step one, the series of 4-chlorophenol solutions mentioned in step four, the series of 4-bromophenol solutions mentioned in step five, and the series of 4-iodophenol solutions mentioned in step five are passed through an activated carbon column at a flow rate of 5 mL / min; the concentration of the nitric acid solution mentioned in steps one, four, and five is 10 mmol / L, and the concentration of the sodium nitrate solution is 10 mmol / L.

4. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The rinsing process described in steps one, four, and five involves three rinsing cycles, using a total of 20 mL of nitric acid or sodium nitrate solution.

5. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The purity of the oxygen mentioned in steps two, four, and five is ≥99.9%; the pyrolysis temperature mentioned in steps two, four, and five is 950 ℃, and the pyrolysis time is 10 min; the volume of the ultrapure water mentioned in steps two, four, and five is 25 mL.

6. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The volume ratio of the filtered absorbent, ultrapure water, chloramine solution, 2,6-dimethylphenol solution, and sodium arsenite solution in steps three and five is 5 mL:4.4 mL:100 μL:400 μL:100 μL.

7. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The concentration of the chloramine solution mentioned in steps three and five is 20 mmol / L; the concentration of the 2,6-dimethylphenol solution mentioned in steps three and five is 50 mmol / L; the concentration of the sodium arsenite solution mentioned in steps three and five is 23 mmol / L; and the reaction time in the dark in steps three and five is 15 min to 20 min.

8. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The ion chromatograph used in step four is the IC6220 ion chromatograph from the Wanyi IC6200 series. The chromatographic column used is a Dionex AS19 column (4 mm × 250 mm), and the autosampler used is an AS3110 autosampler equipped with a conductivity detector. The analytical conditions of the ion chromatograph are as follows: the eluent is 18 mmol / L KOH isocratic elution, the eluent flow rate is 1 mL / min, the column temperature is 30℃, the suppressor current is 54 mA, and the injection volume is 500 µL.

9. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The gradient elution described in step five uses mobile phase I and mobile phase II, with a flow rate of 0.2 mL / min. Mobile phase I is acetonitrile, and mobile phase II is a 0.1% (v / v) formic acid aqueous solution. The injection volume is 20 μL, and the sample is injected through the HPLC column at a flow rate of 0.2 mL / min. Within 0 min to 10 min, the volume fraction of mobile phase I remains at 5%. Within 10 min to 20 min, the volume fraction of mobile phase I linearly increases from 5% to 95%. Within 20 min to 30 min, the volume fraction of mobile phase I remains at 95%. Within 30.1 min to 40 min, the volume fraction of mobile phase I changes to 5%.

10. The method for determining total organic halogens based on activated carbon adsorption, pyrolysis, and ion chromatography / high performance liquid chromatography-mass spectrometry according to claim 1, characterized in that... The HPLC-ESI-QqQ-MS described in step five consists of an Agilent 1260 HPLC coupled with an ABSciex QTrap 5500 MS with a negative ESI source. The Agilent 1260 HPLC is equipped with a Waters Symmetry C18 column (3.0 × 100 mm, 2.5 µm particle size). The MS conditions are as follows: ion source voltage -4500 V; gas I and gas II are both 50 arbitrary units; curtain gas is 35 arbitrary units; ion source temperature is 550°C; declustering potential (DP) is -100 V; collision energy (CE) is -40 V; inlet potential (EP) is -10 V; collision cell outlet potential (CXP) is -15 V.

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