Method for simultaneously determining eight disinfection byproducts in water by using in-situ purge and trap-gas chromatography-mass spectrometry

Abstract

The invention relates to the technical field of disinfection by-product detection, and discloses a method for simultaneously determining eight disinfection by-products in water by using in-situ purge and trap-gas chromatography-mass spectrometry, the method is efficient, sensitive and environment-friendly, the whole-process automatic determination after sample collection is realized, the sample pretreatment and sample determination speed is higher, and the detection accuracy is higher. Zero consumption of harmful reagents is realized. The method comprises the steps of sample collection and pretreatment, qualitative analysis, quantitative analysis and precision and recovery rate analysis. According to the method, salt does not need to be added into the sample, the anti-pollution capacity is high, the detection limit is low, the reproducibility is good, the accuracy is high, and the high standard recovery rate can be achieved under different water quality backgrounds. The method conforms to the green chemistry concept, meets the requirement for large-batch detection, and provides a high-quality technical choice for continuous monitoring and health risk assessment of various low-concentration disinfection by-products in water.

Description

Technical Field

[0001] The present invention belongs to the technical field of disinfection by-product detection, and specifically relates to a method for simultaneously determining two types of eight disinfection by-products in water using in-situ purge and trap-GC-MS. Background Art

[0002] To ensure drinking water safety and inactivate pathogenic microorganisms in water bodies, disinfection is an essential step in the drinking water treatment process. During the disinfection process, disinfectants react with organic and inorganic substances in the water through a series of reactions to produce disinfection by-products (DBPs) that are harmful to human health. These include two common types of carbon-containing disinfection by-products (C-DBPs), trihalomethanes (THMs), and the more toxic nitrogen-containing disinfection by-products (N-DBPs), halogenated acetonitrile (HANs). The World Health Organization (WHO) "Guidelines for Drinking Water Quality (Fourth Edition)" and my country's "Standard for Drinking Water Quality" (GB 5749-2022) both stipulate limit values for some DBPs and include them in management and control to reduce the health risks posed by DBPs.

[0003] DBPs in water are complex and diverse, but the detection limits of current DBPs standard detection methods are mostly mg·L -1 The current level of DBP analysis is limited and can only measure a single type of DBP simultaneously, failing to meet the need for rapid and simultaneous measurement of multiple DBPs. Therefore, establishing accurate, sensitive, simultaneous, and efficient methods for analyzing multiple disinfection byproducts is crucial for DBP control. When testing for DBPs, the appropriate method is often selected based on the characteristics of the DBP.

[0004] Currently, commonly used detection and research methods for DBPs include gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), high-performance liquid chromatography-mass spectrometry (HPLC-MS), ion chromatography, and the combination of chromatography and other detectors such as electron capture detectors (ECD) and ultraviolet detectors. The ECD detector is listed as a standard method by the United States Environmental Protection Agency (USEPA) (USEPA 551.1 and 552.3) for the determination of common disinfection by-products in drinking water. GC-MS can utilize mass spectrometry for qualitative identification, that is, by comparing the mass spectrometric ions of unknown DBPs with data from large mass spectral libraries to identify DBPs. This method has better selectivity and a wider range of applicability, and can avoid the false positive problem of GC-ECD. Therefore, GC-MS has higher accuracy in detecting DBPs.

[0005] The concentration of DBPs in general water bodies is low, making it difficult to reach the instrument detection limit. Therefore, it is necessary to first enrich and concentrate the DBPs in the water body through pretreatment technology, and then detect them on the instrument. The current research trend in the field of disinfection byproduct detection technology is to seek highly automated and environmentally friendly sample pretreatment technologies. Common pretreatment methods include headspace (HS), liquid-liquid extraction (LLE), liquid-liquid microextraction (LLME), solid phase extraction (SPE), solid phase microextraction (SPME), and purge and trap (P&T). Among them, LLE and SPE both require the consumption of harmful reagents; LLME has cumbersome steps and is difficult to achieve automated continuous sampling; and HS has low sensitivity. Compared with SPME, P&T is also a green chemical technology, but it is more popular, with faster sample preparation and lower cost.

[0006] The U.S. Environmental Protection Agency (USEPA) recommends two gas purge and trap methods (5030C and 5030A in SW-846). Method 5030C is often used for water sample pretreatment to determine volatile disinfection byproducts (V-DBPs) in water. However, salt must be added during the measurement process to increase the response intensity, and salt may corrode instrument components and shorten the instrument life. Furthermore, because the purge is performed within the purge tube, the tube is susceptible to contamination by high-concentration pollutants and residual components. Method 5030A, on the other hand, performs in-situ purge and trapping directly within the purge bottle, achieving superior detection results compared to traditional purge and trap methods. It achieves low detection limits without the use of salt, extending instrument life, and has strong anti-contamination capabilities. It enables fully automated measurement of samples after collection, with zero consumption of hazardous reagents. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the present invention provides a method for simultaneously determining eight disinfection by-products in water using in-situ purge and trap-gas chromatography-mass spectrometry, which is characterized by comprising the following steps:

[0008] (1) Sample collection and pretreatment:

[0009] A water sample containing eight DBPs to be tested was filtered through a 0.22 μm membrane, and a volume (V mL) was placed in a purge bottle. A specific concentration of internal standard was added, along with an appropriate amount of ascorbic acid to remove any interference from residual disinfectants. The purge bottle was placed in the sample tray of a multifunctional, fully automated pretreatment platform and directly tested. The measurement was completed within 12 hours.

[0010] (2) Purge and capture:

[0011] Insert the sample into the purge bottle to purge and trap DBPs in water. The purge and trap conditions are as follows: purge temperature: T℃, purge flow rate: Q mL / min, purge time: t min; desorption temperature: T 吸 ℃, desorption time: t吸 min; baking temperature: T 烘烤 ℃, baking flow rate: Q 烘烤 mL / min, baking time: t 烘烤 min.

[0012] (3) Qualitative analysis:

[0013] The pre-treated samples were analyzed using a gas chromatography-mass spectrometer. The chromatographic conditions were as follows: the chromatographic column was an HP-5 column (30 m × 250 μm × 1 μm), high-purity helium (99.999%) was used as the carrier gas; the injection port temperature was T 进样口-1 ℃; Heating program: initial temperature T 0-1 ℃, holding time t 0-1 min, with heating rate v 1-1 ℃ / min heating to T 1-1 ℃, and finally the heating rate v 2-1 ℃ / min rise to T 2-1 ℃; split injection, split ratio R1; flow rate Q 色谱-1 mL / min; Mass spectrometry conditions: transfer line temperature T 传输-1 ℃, ion source mode: EI, ion source temperature T 离子源-1 ℃, acquisition mode: SCAN. Simultaneously, a DBPs standard mixture was tested under the same conditions to obtain a real-time mass spectrum of the standard. By comparing the retention time and characteristic ions of the chromatographic peaks of the standard and sample in the spectrum, the presence of the target compound in the sample was determined.

[0014] Furthermore, after sample pretreatment and purging and trapping, odor substances can be quantitatively analyzed.

[0015] (4) Quantitative analysis:

[0016] After the samples were pre-treated by constant temperature purge trapping, they were tested by gas chromatography-mass spectrometry. The chromatographic conditions were: injection port temperature: T 进样口-2 ℃; Heating program: initial temperature T 0-2 ℃, holding time t 0-2 min, with heating rate v 1-2 ℃ / min heating to T 1-2 ℃, and finally the heating rate v 2-2 ℃ / min rise to T 2-2 ℃; split injection, split ratio R2; flow rate Q 色谱- 2mL / min, mass spectrometry conditions: transfer line temperature T 传输-2 ℃, ion source mode: EI, ion source temperature T 离子源-2℃, acquisition mode: SIM. Then, accurately pipette the standard sample and quantitative internal standard, dilute with ultrapure water to prepare a standard solution. After sample pretreatment and purge-and-trap, place the sample on a sample tray and analyze on the analyzer to obtain a standard curve for standard sample and internal standard quantification. Then, find the corresponding concentration on the standard curve by comparing the response values of the sample and internal standard to determine the DBPs content in the sample.

[0017] Furthermore, the DBPs described in step (1) are: 4 trihalomethanes (THMs): trichloromethane (TCM), dichlorobromomethane (DCBM), dibromochloromethane (DBCM) and tribromomethane (TBM); 4 haloacetonitriles (HANs): trichloroacetonitrile (TCAN), dichloroacetonitrile (DCAN), bromochloroacetonitrile (BCAN) and dibromoacetonitrile (DBAN), and the V is 1-30 mL.

[0018] Furthermore, the internal standard IS added in step (1) and the quantitative analysis is 1,2-dibromopropane (C3H6Br2), and the concentration of the added IS is 2-50 μg / L.

[0019] Furthermore, the T in step (2) is 10-70° C., the Q is 10-80 mL / min, and the t is 5-15 min.

[0020] Furthermore, the desorption and baking conditions in step (2) are as follows: desorption temperature T 吸 10-300℃, desorption time t 吸 1-5min, trap baking temperature T 烘烤 10-300℃, baking gas flow Q 烘烤 50-300mL / min. Baking time t 烘烤 1-10min.

[0021] Furthermore, the T 进样口-1 is 100-250°C; the T 0-1 is 10-50°C, the t 0-1 For 1-5min, the v 1-1 is 1-10℃ / min; the T 1-1 is 10-100°C, the v 2-1 is 10-50℃ / min, the T 2-1 is 100-350℃; the R1 is 1:3-1:100; the Q 色谱-1 is 1-10mL / min; the T 传输-1 is 100-380°C, the T 离子源-1 100-380℃.

[0022] Furthermore, the T 进样口-2 is 100-250°C; the T 0-2 is 10-50°C, the t 0-2 For 1-5min, the v 1-2 is 1-10℃ / min; the T 1-2 is 10-100°C, the v 2-2 is 10-50℃ / min, the T 2-2 is 100-350℃; the R2 is 1:3-1:100; the Q 色谱-2 is 1-10mL / min; the T 传输-2 is 100-380°C, the T 离子源-2 100-380℃.

[0023] The method provided by the present invention has at least the following beneficial effects:

[0024] (1) Compared with conventional organic phase extraction, the present invention achieves zero consumption of harmful reagents, is more in line with the concept of green chemistry, is more environmentally friendly, and avoids the shortcomings of traditional organic solvent methyl tert-butyl ether (MTBE) which is toxic and volatile, has a long liquid-liquid extraction time, and has poor extraction effect.

[0025] (2) The in-situ purge and trap-gas chromatography-mass spectrometry method of the present invention meets the need for simultaneous and rapid determination of multiple DBPs. Since the purge and trap pretreatment can be run synchronously with the gas chromatography-mass spectrometry detection, the sample is collected and the determination is fully automatic. It only takes about 20 minutes to detect a single sample. The detection limit is as low as ng / L level, the reproducibility is good, and a high recovery rate is achieved in various water bodies. It is a highly sensitive and low-interference method suitable for the simultaneous detection of multiple DBPs in water, which meets the detection requirements for accurate and rapid determination of large quantities of volatile disinfection byproducts (V-DBPs).

[0026] (3) Compared with the traditional purge and trap method, the in-situ purge and trap method of the present invention avoids the corrosion and damage of salt to the instrument, has stronger anti-pollution ability, and shows excellent applicability, providing a high-quality technical option for continuous monitoring and health risk assessment of various disinfection by-products in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Flowchart for the detection and analysis of eight disinfection by-products in water using in situ purge and trap-gas chromatography-mass spectrometry.

[0028] Figure 2 The total ion chromatograms of target disinfection byproducts and internal standard 1,2-dibromopropane.

[0029] Figure 3The mass spectra and matching results of the target disinfection by-product and the internal standard 1,2-dibromopropane are shown.

[0030] Figure 4 This is the standard curve of the target disinfection byproducts.

[0031] Description of reference numerals:

[0032] 1. Chloroform 2. Trichloroacetonitrile 3. Bromodichloromethane

[0033] 4. Dichloroacetonitrile 5. Dibromochloromethane 6. Bromochloroacetonitrile

[0034] 7. Bromoform 8. Dibromoacetonitrile 9. 1,2-Dibromopropane DETAILED DESCRIPTION

[0035] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0036] In the present invention, the CAS number of chloroform is 67-66-3, the CAS number of dichlorobromomethane is 75-27-4, the CAS number of dibromochloromethane is 124-48-1, and the CAS number of bromoform is 75-25-2; the CAS number of trichloroacetonitrile is 545-06-2, the CAS number of dichloroacetonitrile is 3018-12-0, the CAS number of bromochloroacetonitrile is 83463-62-1, the CAS number of dibromoacetonitrile is 3252-43-5, and the CAS number of 1,2-dibromopropane is 78-75-1. Specific embodiment 1

[0038] This example provides a P&T-GC-MS method for qualitatively detecting eight DBPs in water. The steps are as follows:

[0039] (1) Sample pretreatment:

[0040] Take the water sample to be tested, filter it through a 0.22μm filter membrane, add 20mL of sample and 0.5mL of internal standard with a concentration of 200μg / L into a purge bottle (with a polytetrafluoroethylene-surfaced silicone diaphragm), and place it in the sample tray waiting for testing.

[0041] (2) Purge and capture:

[0042] The solution volume was 20 mL, and the additional water volume was 0 mL; the purge temperature was 50°C, the purge flow rate was 40 mL / min, and the purge time was 11 min; the desorption temperature was 250°C, and the desorption time was 2.5 min; the trap baking temperature was 280°C, the baking gas flow rate was 200 mL / min, and the baking time was 2 min.

[0043] (3) Qualitative analysis:

[0044] The disinfection by-products in the samples were analyzed and determined by gas chromatography-mass spectrometry. The total ion current chromatogram of the target disinfection by-products is shown in Figure 2 , and further obtain the mass spectrum and matching result diagram of disinfection by-products, such as Figure 3 As shown in the figure, by comparing the retention time and characteristic ions of the chromatographic peaks of the standard and sample, it is determined that the sample contains the target compound.

[0045] The gas chromatography-mass spectrometry parameters were as follows: chromatographic column model: HP-5 (30 m × 250 μm × 1 μm). Inlet temperature: 220°C; carrier gas constant flow mode, flow rate: 1.0 mL / min; column temperature program: initial temperature: 35°C, hold time: 3 min, ramp to 80°C at a rate of 5°C / min, and finally to 220°C at a rate of 40°C / min; injection mode: split injection, split ratio: 1:5; flow rate: 3 mL / min. Mass spectrometry conditions: transfer line temperature: 280°C, ion source mode: EI, ion source temperature: 230°C, acquisition mode: Scan; scan range: 50–300 m / z. Specific embodiment 2

[0047] The P&T-GC-MS method was used for quantitative analysis, and the standard curves and detection limits of eight disinfection by-products were determined.

[0048] (1) Sample pretreatment:

[0049] Take the water sample to be tested, filter it through a 0.22μm filter membrane, add 20mL of sample and 0.5mL of internal standard with a concentration of 200ug / L into the purge bottle, place it in the sample tray, and wait for the sample to be tested.

[0050] (2) Purge and capture:

[0051] The sample was purged according to the set parameters, with a solution volume of 20 mL and an additional water volume of 0 mL; a purge temperature of 50°C, a purge flow rate of 40 mL / min, and a purge time of 11 min; a desorption temperature of 250°C, and a desorption time of 2.5 min; a trap baking temperature of 280°C, a baking gas flow rate of 200 mL / min, and a baking time of 2 min.

[0052] (3) Qualitative analysis:

[0053] The disinfection by-products obtained by sample purge and capture were analyzed and determined by gas chromatography-mass spectrometry. At the same time, the standard water sample was tested under the same conditions to obtain the chromatogram and mass spectrum of the disinfection by-products, such as Figure 2 and Figure 3 As shown in the figure, by comparing the retention time and characteristic ions of the chromatographic peaks of the standard and sample, it is determined that the sample contains the target compound.

[0054] The gas chromatography-mass spectrometry parameters were as follows: chromatographic column model: HP-5 (30 m × 250 μm × 1 μm). Inlet temperature: 220°C; carrier gas constant flow mode, flow rate: 1.0 mL / min; column temperature program: initial temperature: 35°C, hold time: 3 min, ramp to 80°C at a rate of 5°C / min, and finally to 220°C at a rate of 40°C / min; injection mode: split injection, split ratio: 1:5; flow rate: 3 mL / min. Mass spectrometry conditions: transfer line temperature: 280°C, ion source mode: EI, ion source temperature: 230°C, acquisition mode: Scan; scan range: 50–300 m / z.

[0055] (4) Quantitative analysis:

[0056] Standard curve configuration: Mix eight DBPs with a specific concentration of the internal standard, 1,2-dibromopropane, and dilute with ultrapure water to 0.2, 0.5, 1, 2, 3, 5, 10, 15, and 20 μg / L. The concentration of 1,2-dibromopropane was fixed at 5 μg / L. Add 20 mL of the standard sample to a 40 mL purge bottle. Place the sample on the sample tray and analyze.

[0057] The gas chromatography-mass spectrometry parameters were as follows: chromatographic column model: HP-5 (30 m × 250 μm × 1 μm). Inlet temperature: 220°C; carrier gas constant flow mode: 1.0 mL / min; column temperature program: initial temperature: 35°C, hold time: 3 min, ramp to 80°C at a rate of 5°C / min, and finally to 220°C at a rate of 40°C / min; injection mode: split injection, split ratio: 1:5; flow rate: 3 mL / min. Mass spectrometry conditions: transfer line temperature: 280°C, ion source mode: EI, ion source temperature: 230°C, acquisition mode: Sim. The retention times, quantifier ions, and qualifier ions for each target disinfection byproduct are shown in Table 1.

[0058] Table 1 Retention time, quantitative ions and qualitative ions of target disinfection by-products

[0059] Using the selected ion scanning mode, the prepared DBPs mixed standard samples of different concentrations were measured from low concentration to high concentration according to the test method, and the internal standard method was used for quantitative analysis. The standard curve was drawn with the concentration as the horizontal axis and the peak area ratio of the corresponding standard to the internal standard as the vertical axis, as shown in the figure. Figure 4 The results of the standard curves for the eight target DBPs are shown in Table 2. The samples were measured under the same conditions, and the corresponding concentrations were found in the standard curve graph based on the detected response values to determine the content of various target DBPs in the samples.

[0060] (5) Determination of method detection limit

[0061] According to the National Ecological Environment Standard of the People's Republic of China (HJ 168-2020), all steps of sample analysis were followed, and the blank test was repeated n times (n ≥ 7). The results of each measurement were converted into the concentration or content in the sample, and the standard deviation of the n parallel measurements was calculated. The method detection limit was calculated according to the following formula. The calculation results are shown in Table 2.

[0062] MDL=t (n-1,0.99) ×S

[0063] Where: MDL is the method detection limit; n is the number of replicate measurements of the sample; t is the t distribution value (one-sided) when the degree of freedom is n-1 and the confidence level is 99%; S is the standard deviation of n replicate measurements.

[0064] Table 2 Standard curves, correlation coefficients and detection limits of target disinfection byproducts Table 2

[0065] (4) Actual water sample measurement

[0066] Actual water samples from a drinking water treatment plant were taken and tested according to the above method. The test results were as follows: the median concentration of the four THMs was 21.7 μg / L, among which TCM had the highest concentration of 29.2 μg / L; the median concentration of the four HANs was 1.62 μg / L, among which DCAN had the highest concentration of 3.96 μg / L; DBAN was not detected. Specific embodiment three

[0068] Method precision and recovery analysis

[0069] (1) Sample pretreatment:

[0070] Take the water sample to be tested, filter it through a 0.22μm filter membrane, add 20mL of sample and 0.5mL of internal standard with a concentration of 200μg / L into a purge bottle (with a polytetrafluoroethylene-surfaced silicone diaphragm), and place it in the sample tray waiting for testing.

[0071] (2) Purge and capture:

[0072] The sample was purged according to the set parameters, with a solution volume of 20 mL and an additional water volume of 0 mL; purging conditions: purge temperature 50°C, purge flow rate 40 mL / min, purge time 11 min; desorption temperature 250°C, desorption time 2.5 min; trap baking temperature 280°C, baking gas flow rate 200 mL / min, baking time 2 min.

[0073] (3) Quantitative analysis:

[0074] 20 mL of the sample to be tested was filtered and placed into a 40 mL purge bottle, which was then placed in the injection tray for analysis. The target substances in the water sample were captured by in-situ purge and then injected into the gas chromatography-mass spectrometry instrument for analysis and testing.

[0075] The gas chromatography-mass spectrometry parameters were as follows: chromatographic column model: HP-5 (30 m × 250 μm × 1 μm); inlet temperature: 220°C; carrier gas constant flow mode: 1.0 mL / min; column temperature program: initial temperature: 35°C, hold time: 3 min, ramp to 80°C at a rate of 5°C / min, and finally to 220°C at a rate of 40°C / min; injection mode: split injection, split ratio: 1:5; flow rate: 3 mL / min. Mass spectrometry conditions: transfer line temperature: 280°C, ion source mode: EI, ion source temperature: 230°C, acquisition mode: Sim.

[0076] TCM detected ions m / z 83 / 85,87; DCBM detected ions 83 / 85,47; DBCM detected ions 129 / 127,131; TBM detected ions 173 / 171,175; TCAN detected ions 108 / 110,73; DCAN detected ions 74 / 76,155; BCAN detected ions 74 / 82,84; DBAN detected ions 118 / 199,79; internal standard 1,2-dibromopropane detected ions 123 / 41,121.

[0077] The standard curves of the 8 DBPs internal standard method were obtained, such as Figure 4 The samples were tested under the same conditions, and the corresponding concentrations were found in the standard curve using the detected response values to determine the content of various target DBPs in the samples.

[0078] (4) Precision analysis

[0079] Eight DBPs mixed standard solutions were diluted with ultrapure water to concentrations of 0.2 μg / L, 1 μg / L, 5 μg / L, and 20 μg / L, respectively. Multiple measurements were performed, and eight replicates were performed on samples at fixed concentration levels. The relative standard deviation (RSD) was tested. The results are shown in Table 3, indicating that this method has high precision and stability at various concentrations.

[0080] Relative standard deviation (RSD) formula: RSD (%) = standard deviation value / average value

[0081] Table 3 Precision analysis

[0082] (5) Spike recovery analysis

[0083] Eight DBPs mixed standard solutions were spiked into ultrapure water and tap water samples with different background water qualities at concentrations of 1, 5, and 20 μg / L, respectively. Eleven replicates were performed, and the spike recoveries (R%) were calculated and averaged. The results are shown in Table 4. As can be seen from the table, the method achieved high recoveries at different spike concentrations in both samples with different background water qualities.

[0084] The recovery rate (R%) is calculated as follows:

[0085] (R%) = (measured value - sample background value) / spiked amount × 100%

[0086] Table 4 Spike recovery analysis

[0087] In ultrapure water, the recovery rates for each target compound spiked at 1 μg / L were 80.9%-104.3%, at 5 μg / L, they were 79.6%-107.4%, and at 20 μg / L, they were 82.7%-116.1%. In tap water, the recovery rates for each target compound spiked at 1 μg / L were 79.6%-110.8%, at 5 μg / L, they were 77.5%-103.4%, and at 20 μg / L, they were 75.1%-108.7%.

[0088] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for simultaneously determining eight disinfection by-products in water using in-situ purge and trap-gas chromatography-mass spectrometry, characterized in that: The following steps are involved: (1) Sample collection and pretreatment: A water sample containing eight disinfection byproducts to be tested was filtered through a membrane. A volume (V mL) was placed in a purge bottle. A defined concentration of internal standard was added, along with an appropriate amount of ascorbic acid to remove residual disinfectant interference. The purge bottle was placed in the sample tray of a multifunctional, fully automated pretreatment platform and directly tested. The measurement was completed within 12 hours. (2) Purge and capture: Insert the sample into the purge bottle to purge and trap DBPs in water. The purge and trap conditions are as follows: purge temperature: T℃, purge flow rate: Q mL / min, purge time: t min; desorption temperature: T 吸 ℃, desorption time: t 吸 min; baking temperature: T 烘烤 ℃, baking flow rate: Q 烘烤 mL / min, baking time: t 烘烤 min. (3) Qualitative analysis: The pre-treated samples were analyzed using a gas chromatography-mass spectrometer. The chromatographic conditions were as follows: the chromatographic column was an HP-5 column (30 m × 250 μm × 1 μm), high-purity helium (99.999%) was used as the carrier gas; the injection port temperature was T 进样口-1 ℃; Heating program: initial temperature T 0-1 ℃, holding time t 0-1 min, with heating rate v 1-1 ℃ / min heating to T 1-1 ℃, and finally the heating rate v 2-1 ℃ / min rise to T 2-1 ℃; injection method: split injection, split ratio R1; flow rate Q 色谱-1 mL / min; Mass spectrometry conditions: transfer line temperature T 传输-1 ℃, ion source mode: EI, ion source temperature T 离子源-1 ℃, acquisition mode: SCAN. Eight DBPs mixed standards were tested simultaneously under the same conditions to obtain real-time mass spectra of the standards. By comparing the retention times and characteristic ions of the chromatographic peaks of the standards and samples in the spectra, the presence of the target compounds in the samples was determined.

2. The method for simultaneously determining eight disinfection by-products in water using in-situ purge and trap-gas chromatography-mass spectrometry according to claim 1, characterized in that: After sample collection and pretreatment, purge and trap, and qualitative analysis, the following steps are also included: (1) Quantitative analysis: After the samples were pre-treated by constant temperature purge trapping, they were tested using a gas chromatography-mass spectrometer. The instrument operating parameters were as follows: Chromatographic conditions: Inlet temperature: T 进样口-2 ℃; Heating program: initial temperature T 0-2 ℃, holding time t 0-2 min, with heating rate v 1-2 ℃ / min heating to T 1-2 ℃, and finally the heating rate v 2-2 ℃ / min rise to T 2-2 ℃; split injection, split ratio R2; flow rate Q 色谱-2 mL / min, mass spectrometry conditions: transfer line temperature T 传输-2 ℃, ion source mode: EI, ion source temperature T 离子源-2 ℃, acquisition mode: SIM. Then, accurately pipette the standard sample and quantitative internal standard and dilute them with ultrapure water to prepare a series of standard solutions of varying concentrations. After sample pretreatment and purge-and-trap, the samples are placed on a sample tray and analyzed on the analyzer. A standard curve for standard sample and internal standard quantification is generated. The corresponding concentration is then determined on the standard curve using the ratio of the response values detected by the sample to the internal standard, thereby determining the content of the eight DBPs in the sample.

3. The method for simultaneously determining eight disinfection by-products in water using in-situ purge and trap-gas chromatography-mass spectrometry according to claim 1 or 2, characterized in that: The eight DBPs described in step (1) of claim 1 and step (1) of claim 2 are: four trihalomethanes (THMs): trichloromethane (TCM), dichlorobromomethane (DCBM), dibromochloromethane (DBCM) and tribromomethane (TBM); four haloacetonitriles (HANs): trichloroacetonitrile (TCAN), dichloroacetonitrile (DCAN), bromochloroacetonitrile (BCAN) and dibromoacetonitrile (DBAN), and V is 1-30 mL.

4. The method according to claim 1 or 2, characterized in that The internal standard IS described in step (1) of claim 1 and step (1) of claim 2 is 1,2-dibromopropane (C3H6Br2), and the concentration range of added IS is 2-50 μg / L.

5. The method according to claim 1, wherein The T in step (2) is 10-70° C., the Q is 10-80 mL / min, and the t is 5-15 min.

6. The method according to claim 1, characterized in that The desorption and baking conditions described in step (2) are: desorption temperature T 吸 10-300℃, desorption time t 吸 1-5min, trap baking temperature T 烘烤 10-300℃, baking gas flow Q 烘烤 50-300mL / min. Baking time t 烘烤 1-10min.

7. The method according to claim 1, characterized in that T described in step (3) 进样口-1 is 100-250°C; the T 0-1 is 10-50°C, the t 0-1 For 1-5min, the v 1-1 is 1-10℃ / min; the T 1-1 is 10-100°C, the v 2-1 is 10-50℃ / min, the T 2-1 is 100-350℃; the R1 is 1:3-1:100; the Q 色谱-1 is 1-10mL / min; the T 传输-1 is 100-380°C, the T 离子源-1 100-380℃.

8. The method according to claim 2, characterized in that Parameters of the gas chromatography-mass spectrometry instrument described in step (1): T 进样口-2 is 100-250°C; the T 0-2 is 10-50°C, the t 0-2 For 1-5min, the v 1-2 is 1-10℃ / min; the T 1-2 is 10-100°C, the v 2-2 is 10-50℃ / min, the T 2-2 is 100-350℃; the R2 is 1:3-1:100; the Q 色谱-2 is 1-10mL / min; the T 传输-2 is 100-380°C, the T 离子源-2 100-380℃.

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