Method for determining haloacetic acid and oxyhalides

Abstract

The invention discloses a method for determining haloacetic acid and oxyhalide, and belongs to the technical field of water quality analysis and detection. The method for determining haloacetic acid and oxyhalide comprises the following steps: S1, detecting a water sample to be detected by adopting liquid chromatography-mass spectrometry; wherein the chromatographic column is an AG18 chromatographic column; the phase A of the mobile phase is an ammonia water solution with the concentration of 0.3-3 mol / L; the phase B of the mobile phase is acetonitrile or methanol; the volume fraction of the phase A in the mobile phase is 5-50%; and S2, substituting the detected peak area of the substance into the standard working curve to calculate the concentration of the target substance.

Description

Technical Field

[0001] The invention belongs to the technical field of water quality analysis and detection, and more specifically, relates to a method for determining haloacetic acid and halogen oxide. Background Art

[0002] When chlorine is used to disinfect drinking water, in addition to trihalomethanes (THMs), haloacetic acids (HAAs) are the second most common and harmful disinfection byproducts, accounting for 13% of the total disinfection byproducts, but their toxicity is over 90%. Therefore, the detection of HAAs is of great significance to ensure the quality of water supply. Halogen oxides are an important class of inorganic DBPs, mainly including BrO3 - 、ClO3 - and ClO4 - For example, bromate (BrO3 - ) is the most important disinfection byproduct in the process of ozone oxidation of water bodies containing high concentrations of Br-. In addition, bromate (BrO3 - ) is a Class 2B carcinogen. my country's Drinking Water Standard (GB / T5749-2006) limits the concentrations of dichloroacetic acid, trichloroacetic acid and bromate, with maximum limits of 50μg / L, 100μg / L and 10μg / L respectively. Establishing a sensitive, simple and rapid analytical method for haloacetic acid and bromate is the basis for understanding the contamination status of these substances in drinking water and their potential health risks.

[0003] At present, there are many methods for determining haloacetic acids. The most mainstream methods are the standard method provided by the United States Environmental Protection Agency (USEPA, 552.3) and the standard test method "Standard Test Method for Drinking Water - Part 10: Disinfection Byproduct Index" (GB / T 5750-2023) supporting China's "Sanitary Standards for Drinking Water". Both of these detection methods require derivatization of water samples and then gas chromatography detection. Such methods have problems such as complex operation process, low enrichment multiple, and high detection limit, and therefore need to be further improved.

[0004] The greatest advantage of using liquid chromatography technology to determine HAAs in drinking water is that derivatization is not required. Common methods include ion chromatography (IC), high performance liquid chromatography (HPLC), etc. USEPA standard method 557 uses IC-ESI-MS / MS technology to determine 9 kinds of HAAs. The sample can be directly injected. The detection limit of this method is 0.025 - 0.25 μg / L, and the entire separation process takes 55 minutes (A.D. Zaffiro, M. Zimmerman, B.V. Pepich, Rosanne W. Slingsby, R.F. Jack, Christopher A. Pohl, D.J. Munch. EPA United States Agency Environmental Protection, 2009). HAAs are almost completely ionized in water (ionization degree > 99%). Traditional reversed-phase liquid chromatography columns have poor retention of HAAs. Therefore, an ion-pair reagent needs to be added to the mobile phase to convert ionic HAAs into adduct molecular states and then separated. Due to the use of ion-pair reagents, the consumption of drugs increases and the chromatographic column needs to be equilibrated for a long time for each injection. Summary of the Invention

[0005] 1. Problems to be Solved

[0006] In view of the problems such as the long analysis time of existing haloacetic acids, the present invention provides a method for determining haloacetic acids and halogen oxides, which can simultaneously analyze haloacetic acids and halogen oxides.

[0007] 2. Technical Solutions

[0008] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0009] The first aspect of the present invention provides a method for determining haloacetic acids and halogen oxides, including:

[0010] S1. Detect the water sample to be tested by liquid chromatography-mass spectrometry;

[0011] Among them,

[0012] The chromatographic column is an AG18 chromatographic column;

[0013] The A phase of the mobile phase is an ammonia water solution with a concentration of 0.3 - 3 mol / L;

[0014] The B phase of the mobile phase is acetonitrile or methanol;

[0015] The volume fraction of the A phase in the mobile phase is 5 - 50%;

[0016] S2. Substitute the peak area of the detected substance into the standard working curve to calculate the concentration of the target substance.

[0017] It should be noted that the "concentration of aqueous ammonia solution in the A phase of the mobile phase" affects the retention time and response intensity of the analyte on the chromatographic column. If the concentration is too high, the chromatographic peaks of the analyte cannot be separated. If the concentration is too low, the chromatographic peaks of the analyte are too low or no chromatographic peak appears. In addition, the "volume fraction of the A phase in the mobile phase" also affects the chromatographic peak shape and retention time of the analyte. If the volume is too large, the retention time is too short. If the volume is too low, the chromatographic peak of the analyte is very wide, the retention time is too long, or no chromatographic peak appears.

[0018] According to any embodiment of the first aspect of the object of the present invention, the volume fraction of the A phase in the mobile phase is preferably 10-45%;

[0019] Further preferably, the volume fraction of the A phase in the mobile phase is 15-40%.

[0020] According to any embodiment of the first aspect of the object of the present invention, the A phase of the mobile phase is preferably an aqueous ammonia solution with a concentration of 0.4-2.5 mol / L;

[0021] Further preferably, the A of the mobile phase is an aqueous ammonia solution with a concentration of 0.5-2.0 mol / L.

[0022] According to any embodiment of the first aspect of the object of the present invention, it further includes the step of performing solid impurity removal and residual chlorine removal treatment on the water sample to be tested.

[0023] According to any embodiment of the first aspect of the object of the present invention, it further includes the step of performing filtration and residual chlorine removal treatment on the water sample to be tested.

[0024] According to any embodiment of the first aspect of the object of the present invention, the pore size of the filter membrane used for filtration is 0.22-0.45 μm.

[0025] According to any embodiment of the first aspect of the object of the present invention, it further includes the step of drawing a standard working curve.

[0026] According to any embodiment of the first aspect of the object of the present invention, the drawing of the standard working curve includes:

[0027] 1) Preparation of standard solutions: Prepare a series of standard solutions with known concentrations and concentration gradients containing haloacetic acids and halooxides, and control the concentration of each analyte disinfectant by-product in the same standard solution to be the same;

[0028] 2) Detection of standard solutions: Use liquid chromatography-mass spectrometry to detect the prepared standard solutions;

[0029] 3) Data analysis: Taking the concentration of each disinfection by-product as the abscissa and the peak area as the ordinate, respectively plot the standard working curves of haloacetic acids and halooxides;

[0030] According to any embodiment of the first aspect of the object of the present invention, the mass concentrations of the standard solutions can be, for example: 0.5 μg / L, 1 μg / L, 5 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, and 100 μg / L respectively; or they can also be 1 μg / L, 5 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, 100 μg / L, and 200 μg / L respectively.

[0031] According to any embodiment of the first aspect of the object of the present invention, the haloacetic acids include trichloroacetic acid (TCAA), dichloroacetic acid (DCAA);

[0032] The halooxides include bromate (BrO3 - ).

[0033] According to any embodiment of the first aspect of the object of the present invention, when detecting by liquid chromatography-mass spectrometry, the elution order of haloacetic acids and halooxides is in sequence: trichloroacetic acid (TCAA), dichloroacetic acid (DCAA), bromate (BrO3 - ).

[0034] According to any embodiment of the first aspect of the object of the present invention, the A phase and the B phase of the mobile phase are mixed and run according to a volume ratio gradient.

[0035] According to any embodiment of the first aspect of the object of the present invention, within the initial 1.2 minutes (0 - 1.2 minutes), the gradient starts from 5% by volume of the A phase;

[0036] Then, within the next 0.1 minute, it increases to 25 - 30% by volume of the A phase and maintains this ratio for 2 - 3 minutes;

[0037] After that, the volume fraction of the A phase decreases to 5% within 0.1 minute, and the system is equilibrated for 1 minute before the next sample injection.

[0038] According to any embodiment of the first aspect of the object of the present invention, within the initial 1.2 minutes (0 - 1.2 minutes), the gradient starts from 5% by volume of the A phase;

[0039] Then, within the next 0.1 minute, it increases to 25% by volume of the A phase and maintains this ratio for 2 minutes;

[0040] After that, the volume fraction of the A phase decreases to 5% within 0.1 minute, and the system is equilibrated for 1 minute before the next sample injection.

[0041] According to any embodiment of the first aspect of the object of the present invention, the liquid chromatography conditions are as follows:

[0042] Flow rate: 0.15 - 0.35 mL / min;

[0043] Injection volume: 5 - 15 μL;

[0044] Column temperature: 30 °C.

[0045] According to any embodiment of the first aspect of the object of the present invention, the mass spectrometry uses a triple quadrupole mass spectrometer and an electrospray ionization source, and the ion source parameters are as follows: Curtain gas is 28 - 32 L / min;

[0046] Collision gas is medium speed, and the temperature is 420 - 480 °C;

[0047] Ion source gas 1 is 36 - 45 L / min;

[0048] Ion source gas 2 is 36 - 45 L / min.

[0049] According to any embodiment of the first aspect of the object of the present invention, the mass spectrometry uses a triple quadrupole mass spectrometer and an electrospray ionization source, and the ion source parameters are as follows: Curtain gas is 30 L / min, collision gas is medium speed, and the temperature is 450 °C;

[0050] Ion source gas 1 is 40 L / min;

[0051] Ion source gas 2 is 40 L / min;

[0052] According to any embodiment of the first aspect of the object of the present invention, the liquid chromatography conditions are as follows:

[0053] The mode parameters of the multiple reaction monitoring are as follows:

[0054] Declustering potential (DP): -80 - -20 V;

[0055] Entrance potential (EP): -18 - -5 V;

[0056] Collision energy (CE): -40 - -8 eV;

[0057] And collision cell exit potential (CXP): -16 - -5 V;

[0058] Dwell time: 50 - 150 ms.

[0059] Advantageous effects

[0060] Compared with the prior art, the advantageous effects of the present invention are as follows:

[0061] (1) The method for determining haloacetic acids and halooxides provided by the present invention uses an AG18 chromatographic column as the analytical column, which can greatly shorten the analysis time and measure a larger number of samples within a certain period of time.

[0062] Meanwhile, compared with the liquid chromatography-mass spectrometry method using a reversed-phase chromatographic column or a hydrophilic chromatographic column for separation, the method for determining haloacetic acids and halooxides provided by the present invention has the advantages of low detection limit and strong anti-interference ability, and has strong anti-interference against common anions such as sulfate ions.

[0063] (2) The method for determining haloacetic acids and halooxides provided by the present invention uses an AG18 chromatographic column as the analytical column. On this basis, the alkaline eluent (phase A) in its mobile phase can be replaced with an ammonia water solution, and the ammonia water solution is used for elution. Compared with methylamine, sodium hydroxide, potassium hydroxide, etc., the ammonia water solution has weak alkaline corrosion and can be used on the widely popular liquid chromatography-mass spectrometry system without additional ion suppression system.

[0064] (3) The method for determining haloacetic acids and halooxides provided by the present invention uses a liquid chromatography-mass spectrometry instrument, with ammonia water and acetonitrile as the mobile phase, the negative ion mode is selected for mass spectrometry, and the AG18 is used as the analytical column. Compared with the existing ion chromatography method for bromate, the method of the present invention has the advantages of low detection limit and strong anti-interference ability. Description of the Drawings

[0065] Figure 1 It is the chromatogram of dichloroacetic acid, trichloroacetic acid and bromate during the separation by the AG18 chromatographic column in Example 1. Detailed Embodiments

[0066] The present disclosure can be more easily understood by referring to the following description in conjunction with the drawings and examples, all of which form a part of the present disclosure. It should be understood that the present disclosure is not limited to the specific products, methods, conditions or parameters described and / or illustrated herein. Further, the terms used herein are for the purpose of describing specific embodiments by way of example only and are not intended to be limiting unless otherwise specified.

[0067] It should also be understood that, for clarity, certain features of the present disclosure may be described herein in the context of separate embodiments, but may also be provided in combination with each other in a single embodiment. That is, unless clearly incompatible or specifically excluded, each separate embodiment is considered combinable with any other embodiment, and such combination is considered to represent another distinct embodiment. Conversely, for the sake of brevity, the various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, although a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or sub-structure by itself may also be considered an independent embodiment.

[0068] Unless otherwise specified, it should be understood that each individual element in a list and each combination of the individual elements in that list will be construed as a different embodiment. For example, a list of embodiments represented as "A, B, or C" should be construed as including the embodiments "A", "B", "C", "A or B", "A or C", "B or C", or "A, B, or C".

[0069] In the present disclosure, the singular forms of the articles "a", "an", and "the" also include the corresponding plural referents, and a reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Thus, for example, a reference to "a substance" is a reference to at least one of such substance and its equivalents.

[0070] Terms including ordinal numbers such as "first" and "second" may be used to explain various components or fluids, but these components and fluids are not limited by these terms. Thus, without departing from the teachings of the present disclosure, these terms are only used to distinguish one component / fluid from another.

[0071] When items are described by using conjunctive terms such as "…… and / or ……" etc., the description should be understood to include any one of the associated listed items and all combinations of one or more thereof.

[0072] Generally, the use of the term "about" indicates an approximation that may vary depending on the desired properties obtained through the disclosed subject matter, and will be interpreted in a context-dependent manner based on functionality. Thus, one of ordinary skill in the art will be able to interpret a certain degree of variance on a case-by-case basis. In some cases, the number of significant digits used in expressing a particular value may be a representative technique for determining the variance allowed by the term "about". In other cases, a gradient within a series of values may be used to determine the range of variance allowed by the term "about". Further, all ranges in the present disclosure are inclusive and combinable, and a reference to a value stated in a range includes each value within that range.

[0073] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs; the terms and / or any and all combinations including one or more of the related listed items used herein.

[0074] In the mass spectrometry analysis method of the present invention, an AB SCIEX QTRAP 5500 mass spectrometer is used, the ion source is an electrospray ionization source (ESI), and the triple quadrupole mass spectrometry uses a flow injection injection mode to inject a single standard sample, that is, two haloacetic acids including dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) and BrO3 - , determine the mass-to-charge ratio (m / z) of the parent ion and daughter ion of each target compound, and then optimize the declustering potential (DP), focusing potential (FP), entrance potential (EP), collision energy (CE) and collision cell exit potential (CXP) of the negative ion multiple reaction monitoring mode (MRM). The optimized multiple reaction monitoring mode parameters for each target compound are shown in Table 1. Each analyte uses two ion channels.

[0075] Table 1 Multiple reaction monitoring mode parameters for dichloroacetic acid, trichloroacetic acid and BrO3 -

[0076]

[0077] The present invention will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field. The essential features and remarkable effects of the present invention can be reflected from the following embodiments. The described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Therefore, they do not limit the present invention in any way. Those skilled in the art make some non-essential improvements and adjustments based on the content of the present invention, which all belong to the protection scope of the present invention.

[0078] Example 1

[0079] Standard curve and limit of quantification

[0080] 1) Preparation of standard solution: Mix known concentrations of dichloroacetic acid, trichloroacetic acid and BrO3 - to prepare a mixed standard solution with the same concentration of each single disinfection by-product, place it in a brown injection vial, and prepare standard working solutions with mass concentrations of 0.5, 1, 5, 10, 20, 50 and 100 μg / L.

[0081] 2) The separation column used was an AG 18 anion analytical column (2×50 mm) from Thermo Fisher Scientific, with a flow rate of 0.3 mL / min, an injection volume of 10 μL, and a column temperature of 30 °C; mobile phase A was 0.7 mol / L ammonia aqueous solution, and mobile phase B was acetonitrile. The liquid phase used gradient elution as shown in Table 2;

[0082] Table 2 Liquid Phase Gradient Elution Program Table

[0083]

[0084]

[0085] 3) The mass spectrometry used a QTRAP 5500 mass spectrometer from AB SCIEX. The ion source was an electrospray ionization source (ESI). The triple quadrupole mass spectrometry used a flow injection injection mode to inject a single standard sample, namely two haloacetic acids including dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), and BrO3 - . The mass spectrometry used the multiple reaction monitoring mode. The ion source parameters were: curtain gas was 30 L / min, collision gas was medium speed, temperature was 450 °C, ion source gas 1 was 40 L / min, and ion source gas 2 was 40 L / min;

[0086] 4) In the mixed standard solution, calibration curves were constructed for each analyte in the concentration range of 0.5 μg / L to 100 μg / L. By performing eight repeated measurements on the mixed standard containing DCAA, TCAA, and BrO3 - , the detection limit and quantification limit of the newly established gradient elution, non-suppressed IC-ESI-MS / MS method based on the AG18 column were determined. The concentrations of DCAA, TCAA, and BrO3 - in the mixed standard were 1.0 μg / L, 1.0 μg / L, and 0.5 μg / L respectively;

[0087] 5) Using the concentration of each disinfection by-product in the standard solution as the abscissa and the peak area as the ordinate, standard working curves were plotted respectively. The results are shown in Table 3. All target analytes achieved satisfactory linearity, and the determination coefficient (R 2 ) was higher than 0.995.

[0088] Table 3 Standard Curves and Correlation Coefficient R of Three Disinfection By-Products 2

[0089] Equation <![CDATA[Linear coefficient (R 2 )]]> DCAA y = 1264.42x + 518.42 0.9963 TCAA y = 293.68x + 481.55 0.9954 <![CDATA[BrO3 - > y = 653.71x + 470.89 0.9957

[0090] 6) The limit of detection (LOD) was calculated as the standard deviation (SD) × Student's t-value. It was measured 8 times with a degree of freedom of n - 1 = 7. At the 99% confidence level, t was 3. Therefore, LOD = 3 × SD. The limit of quantification (LOQ) was calculated as 3 × LOD. The calculation results are shown in Table 4. All three analytes exhibited relatively low limits of quantification: 0.90 μg / L for DCAA, 0.99 μg / L for TCAA, and - 0.66 μg / L for BrO3. This means that this rapid method is very suitable for high-throughput quantification of DBPs in drinking water treatment plants and environmental monitoring agencies because the LOQ is much lower than the limits specified in the drinking water quality standards of China, the World Health Organization, and the US Environmental Protection Agency.

[0091] Table 4 Sensitivity of three disinfection by-products in this method

[0092]

[0093]

[0094] Example 2

[0095] A water sample was measured multiple times, and the within-day deviation and between-day deviation

[0096] 1) Preparation of standard solution: Mix dichloroacetic acid, trichloroacetic acid, and BrO3 - with known concentrations to prepare a mixed standard solution with the same concentration of each disinfection by-product. Place it in a brown injection vial and dilute the prepared solution to prepare a standard working solution with a mass concentration of 5 μg / L.

[0097] 2) The separation column used was an AG 18 anion analytical column (2 × 50 mm) from Thermo Flsher Scientitific, with a flow rate of 0.3 mL / min, an injection volume of 10 μL, and a column temperature of 30 °C. Mobile phase A was 1.0 mol / L ammonia water solution, and mobile phase B was acetonitrile. The liquid phase used gradient elution mode, as shown in Table 2 in Example 1;

[0098] 3) The mass spectrometry conditions were the same as in Example 1;

[0099] 4) Analysis steps: Measure 3 standard working solutions of 5 μg / L at 9 am on the first day, 3 standard working solutions of 5 μg / L at 1 pm, and 3 standard working solutions of 5 μg / L at 5 pm; Measure 3 standard working solutions of 5 μg / L at 9 am on the second day; Measure 3 standard working solutions of 5 μg / L at 9 am on the third day;

[0100] 5) The test results are shown in Table 5. It can be seen from the table that both the within-day and between-day deviations are less than 10%, and the method has good stability.

[0101] Table 5 Stability of Three Kinds of Disinfection By-products in This Method

[0102]

[0103] Example 3

[0104] Recovery Rate Test in Tap Water

[0105] 1) Preparation of Tap Water and Standard Solution: After quenching the residual chlorine with 100 mg / L ammonium chloride, the water sample was filtered through a 0.45-μm filter membrane. A mixed standard solution with the same concentration of each disinfection by-product was prepared by mixing dichloroacetic acid, trichloroacetic acid and BrO3 - and placed in a brown injection vial to prepare standard working solutions with mass concentrations of 5 μg / L, 20 μg / L and 40 μg / L;

[0106] 2) The separation column used was an AG 18 anion analytical column (2 × 50 mm) from Thermo Flsher Scientitific, with a flow rate of 0.3 mL / min, an injection volume of 10 μL, and a column temperature of 30 °C; Mobile phase A was 1.5 mol / L ammonia aqueous solution, and mobile phase B was acetonitrile. Gradient elution was used for the liquid phase as shown in Table 2 of Example 1;

[0107] 3) The mass spectrometry conditions were the same as those in Example 1;

[0108] 4) Analysis procedure: After measuring the concentration of disinfection by-products in tap water, the concentration of the spiked sample was measured, and the recovery rate was calculated;

[0109] 5) The test results are shown in Table 6 below. The low, medium and high concentration spiked recovery rates of the three disinfection by-products in tap water were good, all between 70% and 110%, and the deviation between multiple measurements was small, between 1.8% and 5.6%.

[0110] Table 6 Recovery Rates of Three Kinds of Disinfection By-products in Tap Water

[0111]

[0112] Comparative Example 3-1

[0113] Comparative Test on Recovery Rate in Tap Water

[0114] This comparative example was basically the same as Example 3, except that:

[0115] When performing liquid chromatography detection in "Step 2)", mobile phase A was 0.4 mol / L ammonia aqueous solution.

[0116] The remaining steps 1)-4) were the same as those in Example 3.

[0117] The test results are shown in Table 7 below. The recovery rates of the three disinfection by-products at low, medium, and high concentrations in tap water are poor, and some of the spiked recovery rates are below 60%.

[0118] Table 7 Recovery Rates of Three Disinfection By-Products in Tap Water

[0119]

[0120] Comparative Example 3-2

[0121] Comparative Test of Recovery Rates in Tap Water

[0122] This comparative example is basically the same as Example 3, with the only difference being that:

[0123] During the "step 2) liquid chromatography detection", mobile phase A is 2.2 mol / L ammonia water solution.

[0124] The remaining steps 1) to 4) are the same as those in Example 3.

[0125] The test results are shown in Table 8 below. The recovery rates of the three disinfection by-products at medium and high concentrations in tap water are poor, and some of the spiked recovery rates are higher than 120%.

[0126] Table 8 Recovery Rates of Three Disinfection By-Products in Tap Water

[0127]

[0128] Example 4

[0129] Interference of Inorganic Ion Chloride

[0130] 1) Preparation of standard solution: Mix known concentrations of dichloroacetic acid, trichloroacetic acid, and BrO3 - to prepare a mixed standard solution with the same concentration of each disinfection by-product, place it in a brown injection vial, and prepare a standard working solution with a mass concentration of 5 μg / L.

[0131] 2) Add different volumes of chloride ion standard solution to the working solution to make the chloride ion concentration 25 μg / L, 50 μg / L, 100 μg / L, and 200 μg / L.

[0132] 3) The separation column uses an AG 18 anion analytical column (2 × 50 mm) from Thermo Flsher Scientitific, the flow rate is 0.3 mL / min, the injection volume is 10 μL, and the column temperature is 30°C; mobile phase A is 2.0 mol / L ammonia water solution, and mobile phase B is acetonitrile. The liquid phase uses gradient elution mode as shown in Table 2 of Example 1.

[0133] 4) The mass spectrometry conditions are the same as those in Example 1.

[0134] 5) The test results are shown in Table 9 below, for DCAA and BrO3 - The recovery rates are all between 70% and 100% under the influence of chloride ions at various concentrations, and it has good resistance to low chloride ion interference. However, when the chloride ion concentration is relatively high, the recovery rate of TCAA is close to 60%, and the accuracy of the analysis may be affected.

[0135] Table 9 Recovery rates of three disinfection by-products under different chloride ion interferences

[0136]

[0137] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for measuring haloacetic acid and oxyhalide, characterized in that, Includes steps: S1. Use liquid chromatography-mass spectrometry to detect the water sample to be tested; in, The chromatographic column is an AG18 chromatographic column; Phase A of the mobile phase is a 0.3-3 mol / L ammonia solution; Phase B of the mobile phase is acetonitrile or methanol; The volume fraction of phase A in the mobile phase is 5 to 50%; S2. Substitute the peak area of ​​the detected substance into the standard working curve to calculate the concentration of the target substance.

2. The method for measuring haloacetic acid and oxyhalide according to claim 1, wherein The volume fraction of phase A in the mobile phase is 10 to 45%; Phase A of the mobile phase is a 0.4-2.5 mol / L ammonia solution.

3. The method for measuring haloacetic acid and oxyhalide according to claim 1, characterized in that, The volume fraction of phase A in the mobile phase is 15-40%; Phase A of the mobile phase is preferably a 0.5-2.0 mol / L ammonia solution.

4. The method for determining haloacetic acid and oxyhalide according to any one of claims 1 to 3, characterized in that: The liquid chromatography uses the mobile phase for gradient elution.

5. The method for measuring haloacetic acid and oxyhalide according to claim 4, characterized in that, The mass spectrometer uses a negative ion multiple reaction monitoring mode to scan characteristic parent ions and daughter ions of the substance to be tested.

6. The method for measuring haloacetic acid and oxyhalide according to claim 5, characterized in that, The mobile phase A and B are mixed and run according to a volume ratio gradient; In 0–1.2 min, the gradient started from 5% volume fraction of phase A; Then, the volume fraction of phase A was increased to 25-30% in the next 0.1 min, and this ratio was maintained for 2-3 min; Afterwards, the volume fraction of phase A was reduced to 5% within 0.1 min, and the system was equilibrated for 1 min before the next sample injection.

7. The method for measuring haloacetic acid and oxyhalide according to claim 6, characterized in that, The liquid chromatography conditions are: Flow rate: 0.15~0.35mL / min; Injection volume: 5-15 μL; Column temperature: 30℃.

8. The method for measuring haloacetic acid and oxyhalide according to claim 5, characterized in that, The mass spectrometer adopts a triple quadrupole mass spectrometer and an electrospray ion source; The ion source parameters are: curtain gas 28-32 L / min; The collision gas was medium speed and the temperature was 450°C; Ion source gas 1 is 36-45 L / min; The ion source gas 2 is 36-45 L / min.

9. The method for determining haloacetic acid and oxyhalide according to any one of claims 1 to 3 and 5 to 9, characterized in that: The mode parameters of the multiple reaction monitoring are: Declustering voltage: -80~-20V; Inlet voltage: -18~-5V; Collision energy: -40~-8eV; Collision chamber exit voltage: -16~-5V; Dwell time: 50~150ms.

10. The method for determining haloacetic acid and oxyhalide according to any one of claims 1 to 2, characterized in that: It also includes the steps of drawing a standard working curve; The drawing of the standard working curve comprises: 1) Preparation of standard solutions: Prepare a series of standard solutions containing haloacetic acid and oxyhalide with known concentrations and a concentration gradient, and control the concentration of each disinfection byproduct to be tested in the same standard solution to be the same; 2) Detection of standard solution: Detection is performed using a prepared standard solution coupled with liquid chromatography-mass spectrometry; 3) Data analysis: With the concentration of each disinfection by-product as the horizontal axis and the peak area as the vertical axis, the standard working curves of haloacetic acid and halogen oxide were drawn respectively.

Images