Method for analyzing polar iodinated disinfection by-products in drinking water

Abstract

The invention relates to a method for analyzing polar iodinated disinfection by-products in drinking water. The method comprises the following steps: step 1, filtering a water sample to be detected through a filter membrane; step 2, adjusting the pH value of the filtered water sample to 0 and / or 6; step 3, adsorbing the water sample with the adjusted pH value through an activated solid-phase extraction column, and eluting with an eluent to obtain an eluent containing polar iodinated disinfection by-products; step 4, carrying out nitrogen blowing concentration on the elution solution containing the iodinated disinfection by-product to obtain a concentrated solution; 5, acetonitrile is added into the concentrated solution, and ultrapure water is added for dilution before detection; step 6, filtering the diluted solution through a filter membrane again to obtain a sample solution; and step 7, detecting the sample solution by adopting HPLC-MS / MS. Compared with the prior art, the invention establishes a solid-phase extraction-liquid chromatography-mass spectrometry analysis method suitable for analysis of six types of 35 polar iodinated disinfection byproducts in drinking water.

Description

Technical Field

[0001] This invention belongs to the field of analytical technology, specifically relating to an analytical method for polar iodine disinfection byproducts in drinking water. Background Technology

[0002] Drinking water disinfection represents a significant advancement in public health, providing effective protection against aquatic epidemics. However, disinfection also leads to health risks associated with disinfection byproducts, such as cancer and reproductive / developmental disorders. Disinfection byproducts are substances generated during the disinfection process through chemical reactions between disinfectants and organic matter and inorganic ions (such as bromide and iodide ions) in the water. These byproducts typically have carcinogenic, mutagenic, and teratogenic effects, thus attracting widespread attention worldwide. More than 700 disinfection byproducts have been identified in drinking water, and polar iodinated disinfection byproducts, a newly discovered class in recent years, have garnered significant attention due to their relatively high toxicity.

[0003] Currently reported polar iodinated disinfection byproducts mainly include six categories: iodophenol, iodonitrophenol, iodohydroxybenzaldehyde, iodohydroxybenzoic acid, iodobenzoquinone, and iodoacetic acid.

[0004] However, there is currently a lack of unified methods for the analysis of these six types of polar iodinated disinfection byproducts. In particular, the water sample pretreatment methods for the analysis of polar iodinated disinfection byproducts are not yet perfect. For example, iodoacetic acid, iodophenol, iodonitrophenol, iodohydroxybenzaldehyde, and iodohydroxybenzoic acid disinfection byproducts are often pretreated using liquid-liquid extraction, i.e., extraction with methyl tert-butyl ether under acidic conditions. However, when using this method for water sample pretreatment, iodoacetic acid substances require a complex derivatization process, which not only consumes a large amount of organic reagents, but also the recovery rate of iodoacetic acid and iodobenzoquinone cannot meet the analytical requirements. Therefore, this method is not suitable for the pretreatment of water samples for the analysis of iodoacetic acid and iodobenzoquinone.

[0005] Patent application CN109212081A discloses an analytical method for the simultaneous detection of iodoacetic acid and aromatic iodo-disinfection byproducts in water. By using an Oasis MAX solid-phase extraction column and HPLC-MS / MS technology in water, and optimizing extraction conditions, the method solves the problem of low iodoacetic acid recovery in liquid-liquid extraction methods, achieving efficient simultaneous detection of iodoacetic acid and aromatic iodo-disinfection byproducts, thus improving analytical accuracy and efficiency. However, this analytical method only includes six substances, which is insufficient for analyzing many reported polar iodo-disinfection byproducts.

[0006] Patent CN114113370A discloses an analytical method for aromatic halogenated disinfection byproducts in water. This method utilizes an Oasis HLB solid-phase extraction column and nitrogen blowing concentration technology, combined with pH adjustment and HPLC-MS / MS detection. It solves the problem of low recovery rates in the analysis of aromatic halogenated disinfection byproducts in water, achieving efficient analysis of 81 substances and improving the detection limit and recovery rate. However, this analytical method cannot simultaneously detect haloacetic acids, and the detection limits for some substances remain relatively high.

[0007] In summary, the currently published patents all target aliphatic disinfection byproducts, aromatic halogenated disinfection byproducts, or a limited number of polar iodinated disinfection byproducts. They are insufficient to achieve simultaneous detection of the six major categories of polar iodinated disinfection byproducts in drinking water, namely iodoacetic acid, iodophenol, iodonitrophenol, iodohydroxybenzaldehyde, iodohydroxybenzoic acid, and iodobenzoquinone. Further adjustments and optimizations are needed. Summary of the Invention

[0008] The purpose of this invention is to provide an analytical method for polar iodinated disinfection byproducts in drinking water, which can simultaneously analyze 35 polar iodinated disinfection byproducts from 6 categories, including iodoacetic acid, iodophenol, iodonitrophenol, iodohydroxybenzaldehyde, iodohydroxybenzoic acid, and iodobenzoquinone.

[0009] The objective of this invention can be achieved through the following technical solution: a method for analyzing polar iodinated disinfection byproducts in drinking water, comprising the following steps:

[0010] Step 1, Filtration: Filter the water sample to be tested through a filter membrane;

[0011] Step 2, Adjust pH: Adjust the pH of the filtered water sample to 0 and / or 6;

[0012] Step 3, Solid-phase extraction: The pH-adjusted water sample is adsorbed through an activated solid-phase extraction column, and then eluted with an eluent to obtain an eluent solution containing polar iodine disinfection byproducts.

[0013] Step 4, nitrogen blowing concentration: The elution solution containing iodine disinfection byproducts is concentrated by nitrogen blowing to obtain a concentrated solution;

[0014] Step 5, Dilution: Add acetonitrile to the concentrate and dilute with ultrapure water before testing;

[0015] Step 6, filtration again: Filter the diluted solution through a filter membrane again to obtain the sample solution;

[0016] Step 7, Liquid chromatography-mass spectrometry: The sample solution was analyzed using HPLC-MS / MS.

[0017] Furthermore, the filter membrane used in steps 1 and 6 is a filter membrane with a thickness of 0.4 to 0.5 μm.

[0018] Further, in step 1, the water sample to be tested is divided into two identical portions, filtered, and the pH is adjusted to 0 and 6 respectively, and the polar iodine disinfection byproducts in the water sample are detected.

[0019] Furthermore, the polar iodinated disinfection byproducts in the water sample include one or more of the following: iodoacetic acid, iodophenol, iodonitrophenol, iodohydroxybenzaldehyde, iodohydroxybenzoic acid, and iodobenzoquinone.

[0020] Furthermore, iodoacetic acid disinfection byproducts include one or more of monoiodoacetic acid, chloroiodoacetic acid, bromoiodoacetic acid, and diiodoacetic acid;

[0021] Iodinated phenolic disinfection byproducts include one or more of the following: 4-iodophenol, 2-iodophenol, 2,4,6-triiodophenol, 2-chloro-4-iodophenol, 2,6-diiodo-4-chlorophenol, 2-iodo-4-bromophenol, 2,6-diiodo-4-bromophenol, 2-chloro-6-iodophenol, 2-bromo-4-iodophenol, 2,6-dichloro-4-iodophenol, 2-iodo-4-chlorophenol, 2,4-dibromo-4-iodophenol, and 2,4-dichloro-6-iodophenol.

[0022] Iodinated nitrophenol disinfection byproducts include one or more of 2,6-diiodo-4-nitrophenol, 4-iodo-2-nitrophenol, and 2-iodo-4-nitrophenol.

[0023] Iodohydroxybenzaldehyde disinfection byproducts include one or more of 3,5-diiodo-4-hydroxybenzaldehyde, 3-iodo-4-hydroxybenzaldehyde, 5-iodosalicylic acid aldehyde, and 3-bromo-5-iodo-4-hydroxybenzaldehyde;

[0024] Iodohydroxybenzoic acid disinfection byproducts include one or more of the following: 3,5-diiodosalicylic acid, 3-iodo-4-hydroxybenzoic acid, 5-iodosalicylic acid, 3-iodo-5-bromosalicylic acid, 3-bromo-5-iodosalicylic acid, and 3-bromo-5-iodo-4-hydroxybenzoic acid.

[0025] Iodobenzoquinone disinfection byproducts include one or more of the following: 2-iodo-1,4-benzoquinone, 2-chloro-6-iodo-1,4-benzoquinone, 2-bromo-6-iodo-1,4-benzoquinone, 2,3-diiodo-1,4-benzoquinone, and 2,6-diiodo-1,4-benzoquinone.

[0026] Furthermore, when the pH value is adjusted to 0 in step 2, the polar iodinated disinfection byproducts detected in the water sample include one or more of the following: 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, 3-bromo-5-iodosalicylic acid, and iodobenzoquinone disinfection byproducts.

[0027] When the pH value is adjusted to 6 in step 2, the polar iodinated disinfection byproducts detected in the water sample include one or more of the following: iodoacetic acid, iodophenol, iodonitrophenol, iodohydroxybenzaldehyde, and iodohydroxybenzoic acid.

[0028] Furthermore, in step 3, the solid-phase extraction column used is an Oasis MAX solid-phase extraction column, and the activation method of the solid-phase extraction column is as follows: methanol and ultrapure water are sequentially passed through the solid-phase extraction column to activate it.

[0029] Furthermore, in step 3, during adsorption, the flow rate of the water sample through the solid-phase extraction column is 3–5 mL / min; the eluent used is methanol containing 4–8 v / v% formic acid.

[0030] Furthermore, in step 4, the temperature of nitrogen blowing concentration is controlled at <30℃; in step 5, during dilution, the volume ratio of concentrate, acetonitrile and ultrapure water is 1:(1~2):(2~3).

[0031] Furthermore, in step 7, when using HPLC-MS / MS to detect the sample solution, for the sample solution in step 2 with the pH adjusted to 6, mobile phase I and mobile phase II are used for detection, respectively; for the sample solution in step 2 with the pH adjusted to 0, mobile phase I and mobile phase III are used for detection, respectively.

[0032] When using HPLC-MS / MS to analyze sample solutions, the HPLC settings are as follows:

[0033] Both mobile phase I and mobile phase II consist of ultrapure water as phase A and acetonitrile as phase B; mobile phase III consists of a formic acid solution with a volume concentration of 0.05–0.15% as phase A and acetonitrile as phase B; the flow rates of both mobile phase I and mobile phase III are 0.2–0.4 mL / min.

[0034] The gradient elution program for mobile phases I and III is as follows: 0-1 min, maintain 90% A phase constant; 1-12 min, linearly change from 90% A phase to 10% A phase; 12-14 min, maintain 10% A phase constant; 14-14.1 min, rapidly change from 10% A phase to 90% A phase; 14.1-16 min, maintain 90% A phase constant.

[0035] The flow rate of mobile phase II is 0.4–0.6 mL / min; the gradient elution program of mobile phase II is as follows: 0–12 min, linearly changing from 90% phase A to 10% phase A; 12–12.1 min, rapidly changing from 10% phase A to 90% phase A; 12.1–15 min, maintaining 90% phase A.

[0036] When using HPLC-MS / MS to analyze sample solutions, the mass spectrometry settings are as follows:

[0037] The MRM mode is adopted; the collision activation dissociation gas pressure is 3-5 psi, the curtain gas pressure is 35-45 psi, the pressure of ion source gas 1 and 2 is 40-50 psi, and the ion source temperature is 450-550℃.

[0038] The detection was performed using ESI negative ion mode. The settings for ESI negative ion mode were: voltage -4300 to -4600V, inlet potential -8 to -12V, and collision cell outlet potential -13 to -16V.

[0039] Furthermore, the mass spectrometry parameters (mass-to-charge ratio of the parent ion (MS1), mass-to-charge ratio of the daughter ion (MS2), declustering voltage (DP), and collision energy (CE)) of 35 polar iodine disinfection byproducts are shown in Table 1:

[0040]

[0041]

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. This invention employs an Oasis MAX solid-phase extraction column (a hybrid anion exchange column) to establish a solid-phase extraction method suitable for the analysis of 35 polar iodinated disinfection byproducts from 6 categories in drinking water. Using this method, the recovery rate of polar iodinated disinfection byproducts is greater than 70%, solving the problems of derivatization, low recovery rate, and high detection limit of polar iodinated disinfection byproducts in traditional liquid-liquid extraction methods. Furthermore, it can simultaneously determine iodoacetic acids and 5 categories of aromatic iodinated disinfection byproducts.

[0044] 2. Patent CN114113370A uses an Oasis HLB solid-phase extraction column (reverse-phase adsorption column). Because iodoacetic acid derivatives readily ionize into anions in water, they are more easily adsorbed by anion-exchange solid-phase extraction columns than by reverse-phase adsorption columns. Therefore, the Oasis HLB solid-phase extraction column has a low recovery rate for iodoacetic acid derivatives and cannot simultaneously detect them. While patent application CN109212081A uses an Oasis MAX solid-phase extraction column, it only includes six polar iodo disinfection byproducts, which is not applicable to the many polar iodo disinfection byproducts currently reported. This invention overcomes the limitation of most current methods that can only determine a few polar iodo disinfection byproducts. This invention adjusts the pH of the water sample to 0 and 6, significantly enhancing the adsorption efficiency of polar iodo disinfection byproducts. Under strongly acidic conditions (pH 0), the protonation degree of iodobenzoquinones is increased, making them more easily adsorbed by the solid-phase extraction column; while pH 6 optimizes the adsorption of iodoacetic acid and iodophenol. In contrast, while the pH 1.0 and 7.5 of patent CN114113370A are suitable for some aromatic iodosterectomy byproducts, their adsorption effect on the more polar iodoacetic acid byproducts is insufficient, resulting in low recovery rates or undetectable levels. Simultaneously, controlling the flow rate at 3–5 mL / min reduces the mass transfer resistance of the sample passing through the solid-phase extraction column, ensuring sufficient contact between polar iodosterectomy byproducts and the adsorbent. Furthermore, using methanol containing 4–8% formic acid as the eluent enhances the elution capacity, especially for iodophenols and iodonitrophenols, significantly improving their protonation and solubility. Patent CN109212081A uses only methanol elution containing 4% formic acid, which has insufficient desorption efficiency for iodophenols, resulting in low recovery rates for some compounds. The optimized conditions (pH and eluent) of this invention are designed specifically for the physicochemical characteristics of polar iodosterectomy byproducts (such as high polarity and easy protonation), enabling simultaneous analysis of 35 target analytes. While the method in patent application CN109212081A is applicable to 81 aromatic halogenated disinfection byproducts, its conditions cannot simultaneously guarantee high recovery rates for highly polar iodosterectomy byproducts, especially highly polar compounds such as iodoacetic acid, which are not covered in existing technologies. This invention enables simultaneous analysis of six major classes of highly toxic polar iodosterectomy byproducts in drinking water, significantly improving analytical efficiency.

[0045] 3. The method of the present invention has very high sensitivity, and the detection limit for most targets can be as low as 0.04 ng / L, which is better than most reported methods.

[0046] 4. The solid-phase extraction-liquid chromatography-mass spectrometry (LC-MS) analytical method established in this invention can simultaneously analyze 35 polar iodinated disinfection byproducts of 6 categories in drinking water. It overcomes the shortcomings of existing studies, such as the small number of detectable compounds and poor sensitivity, and provides a scientific and effective method for understanding and studying these highly toxic drinking water disinfection byproducts. Attached Figure Description

[0047] Figure 1 The results of the detection of iodophenol disinfection byproducts in Example 5;

[0048] Figure 2 The results of the detection of iodonitrophenol disinfection byproducts in Example 5;

[0049] Figure 3 The results of the detection of disinfection byproducts of iodohydroxybenzaldehyde in Example 5;

[0050] Figure 4 The results of the detection of iodohydroxybenzoic acid disinfection byproducts in Example 5;

[0051] Figure 5 The results of the detection of iodobenzoquinone disinfection byproducts in Example 5;

[0052] Figure 6 The results are the detection results of iodoacetic acid disinfection byproducts in Example 5. Detailed Implementation

[0053] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Unless otherwise specified, the HPLC settings for detecting the sample solutions using HPLC-MS / MS are as follows in the following examples:

[0055] Chromatographic column type: X Select HSS T3 column, 2.1×100mm, packing particle size 3.5μm, Waters; column temperature: 40℃; injection volume: 5μL; mobile phase I and mobile phase II both use ultrapure water as phase A and acetonitrile as phase B; mobile phase III uses 0.1% formic acid solution as phase A and acetonitrile as phase B; the flow rate of mobile phase I and mobile phase III is 0.3mL / min; the gradient elution program of mobile phase I and mobile phase III is: 0–1min, maintain 90% phase A; 1–12min, linearly change from 90% phase A to 10% phase A; 12–14min, maintain 10% phase A; 14–14.1min, rapidly change from 10% phase A to 90% phase A; 14.1–16min, maintain 90% phase A. Phase A remains unchanged; the flow rate of mobile phase II is 0.5 mL / min; the gradient elution program of mobile phase II is as follows: 0–12 min, linearly changing from 90% phase A to 10% phase A; 12–12.1 min, rapidly changing from 10% phase A to 90% phase A; 12.1–15 min, maintaining 90% phase A unchanged.

[0056] The mass spectrometry settings are as follows:

[0057] MRM mode is used; collision activation dissociation pressure is 4 psi, curtain pressure is 40 psi, ion source gas pressure 1 and 2 are both 45 psi, and ion source temperature is 500℃.

[0058] The detection was performed using ESI negative ion mode; the settings for ESI negative ion mode were: voltage -4500V, inlet potential -10V, and collision cell outlet potential -14V.

[0059] Example 1: pH optimization of water samples containing disinfection byproducts of iodophenols, iodonitrophenols, iodohydroxybenzaldehyde, and iodohydroxybenzoic acid.

[0060] Optimal water samples were selected for analysis of disinfection byproducts including iodophenols, iodonitrophenols, iodohydroxybenzaldehyde, and iodohydroxybenzoic acid. The analysis included the following steps:

[0061] Step (1) Preparation of standard solution: Prepare 1L of standard solution containing 26 iodophenol disinfection byproducts. The 13 iodophenol disinfection byproducts include: 4-iodophenol, 2-iodophenol, 2,4,6-triiodophenol, 2-chloro-4-iodophenol, 2,6-diiodo-4-chlorophenol, 2-iodo-4-bromophenol, 2,6-diiodo-4-bromophenol, 2-chloro-6-iodophenol, 2-bromo-4-iodophenol, 2,6-dichloro-4-iodophenol, 2-iodo-4-chlorophenol, 2,4-dibromo-4-iodophenol, and 2,4-dichloro-6-iodophenol; the 3 iodonitrophenol disinfection byproducts include: The disinfection byproducts included 2,6-diiodo-4-nitrophenol, 4-iodo-2-nitrophenol, and 2-iodo-4-nitrophenol; four iodohydroxybenzaldehyde disinfection byproducts including 3,5-diiodo-4-hydroxybenzaldehyde, 3-iodo-4-hydroxybenzaldehyde, 5-iodo-4-hydroxybenzaldehyde, and 3-bromo-5-iodo-4-hydroxybenzaldehyde; and six iodohydroxybenzoic acid disinfection byproducts including 3,5-diiodosalicylic acid, 3-iodo-4-hydroxybenzoic acid, 5-iodosalicylic acid, 3-iodo-5-bromosalicylic acid, 3-bromo-5-iodosalicylic acid, and 3-bromo-5-iodo-4-hydroxybenzoic acid; the concentration of each substance was 50 ng / L.

[0062] Step (2), pH adjustment: Select pH values ​​0-10 and compare the solid phase extraction effects of the eleven methods. Specifically, adjust the standard solution to the specified pH values, which are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 respectively.

[0063] Step (3) Solid phase extraction: The pH-adjusted standard solution is passed through an activated Oasis MAX solid phase extraction column (activated sequentially with 6 mL of methanol and 6 mL of ultrapure water) at a flow rate of 4 mL / min, and eluted with 3 mL of methanol containing 4 v / v% formic acid to obtain the eluent; Step (4) Nitrogen blowing concentration: The eluent is blown with nitrogen to 0.2 mL to obtain the concentrate;

[0064] Step (5) Dilution and filtration: Add 0.3 mL of acetonitrile to the concentrate, and before detection, add 0.5 mL of ultrapure water for dilution, and then filter through a 0.45 μm filter membrane.

[0065] Step (6), Detection: The sample was detected by HPLC-MS / MS, and the recovery rate was calculated. The results are shown in Table 2.

[0066]

[0067]

[0068] As shown in Table 2, when the water sample was adjusted to pH 0, the recoveries of 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, and 3-bromo-5-iodosalicylic acid were the highest, all exceeding 70%. Therefore, pH 0 was selected as the optimal pH for these substances. Since iodoacetic acids exhibited high recoveries at pH 6, pH 6 was chosen as the optimal pH for both iodoacetic acids and other substances.

[0069] Example 2: Optimization of elution conditions for disinfection byproducts of iodophenols, iodonitrophenols, iodohydroxybenzaldehyde, iodohydroxybenzoic acid, and iodoacetic acid.

[0070] Methanol containing 4v / v% formic acid, 5v / v% formic acid, 6v / v% formic acid, 7v / v% formic acid, and 8v / v% formic acid were selected as eluents, and their elution effects were compared.

[0071] When optimizing the elution conditions for disinfection byproducts of iodophenols, iodonitrophenols, iodohydroxybenzaldehydes, iodohydroxybenzoic acids, and iodoacetic acids, the concentration of each substance was 50 ng / L.

[0072] The optimal elution conditions for disinfection byproducts of iodophenols, iodonitrophenols, iodohydroxybenzaldehydes, iodohydroxybenzoic acids, and iodoacetic acids were selected, including the following steps:

[0073] Step (1) Preparation of standard solution: Prepare 1L of standard solution containing 30 polar iodinated disinfection byproducts. The 13 iodophenolic disinfection byproducts include: 4-iodophenol, 2-iodophenol, 2,4,6-triiodophenol, 2-chloro-4-iodophenol, 2,6-diiodo-4-chlorophenol, 2-iodo-4-bromophenol, 2,6-diiodo-4-bromophenol, 2-chloro-6-iodophenol, 2-bromo-4-iodophenol, 2,6-dichloro-4-iodophenol, 2-iodo-4-chlorophenol, 2,4-dibromo-4-iodophenol, and 2,4-dichloro-6-iodophenol; the 3 iodonitrophenolic disinfection byproducts include 2,6-diiodo-4- Nitrophenol, 4-iodo-2-nitrophenol, 2-iodo-4-nitrophenol; four iodohydroxybenzaldehyde disinfection byproducts including 3,5-diiodo-4-hydroxybenzaldehyde, 3-iodo-4-hydroxybenzaldehyde, 5-iodo-4-hydroxybenzaldehyde, 3-bromo-5-iodo-4-hydroxybenzaldehyde; six iodohydroxybenzoic acid disinfection byproducts including 3,5-diiodosalicylic acid, 3-iodo-4-hydroxybenzoic acid, 5-iodosalicylic acid, 3-iodo-5-bromosalicylic acid, 3-bromo-5-iodosalicylic acid, 3-bromo-5-iodo-4-hydroxybenzoic acid; four iodoacetic acid disinfection byproducts including monoiodoacetic acid, chloroiodoacetic acid, bromoiodoacetic acid, and diiodoacetic acid.

[0074] Step (2), Adjust pH: Adjust the pH of the standard solution to 6;

[0075] Step (3), Activation: Activate by sequentially passing 6 mL of methanol and 6 mL of ultrapure water through an Oasis MAX solid-phase extraction column;

[0076] Step (4), Adsorption: Pass the standard solution through the solid phase extraction column at a flow rate of 4 mL / min;

[0077] Step (5), Elution: Elute with 3 mL of elution buffer;

[0078] Step (6), Nitrogen blowing concentration: Blow nitrogen into the eluent until it reaches 0.2 mL, obtaining a concentrated solution.

[0079] Step (7) Dilution and filtration: Add 0.3 mL of acetonitrile to the concentrate, and before detection, add 0.5 mL of ultrapure water for dilution, and then filter through a 0.45 μm filter membrane.

[0080] Step (8), Detection: The sample was detected by HPLC-MS / MS, and the recovery rate was calculated. The results are shown in Table 3.

[0081]

[0082]

[0083] As shown in Table 3, when the elution condition is methanol containing 8 v / v% formic acid, the recovery rates of iodophenol disinfection byproducts (excluding 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, and 3-bromo-5-iodosalicylic acid) are 71.6-121.2%, and the recovery rates of iodoacetic acid disinfection byproducts are 72.1-92.3%, which are higher than other elution conditions. Therefore, methanol containing 8 v / v% formic acid was selected as the elution condition.

[0084] Example 3: Recovery and detection limits of 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, 3-bromo-5-iodosalicylic acid and iodobenzoquinone disinfection byproducts determined by solid-phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS)

[0085] When conducting recovery tests, two concentration gradients were selected, and each substance was prepared into two portions with concentrations of 5 ng / L and 50 ng / L, respectively.

[0086] The determination of iodobenzoquinone disinfection byproducts by HPLC-MS / MS includes the following steps:

[0087] Step (1) Preparation of standard solution: Prepare 1L of standard solution containing 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, 3-bromo-5-iodosalicylic acid and 5 iodobenzoquinone disinfection byproducts. The 5 iodobenzoquinone disinfection byproducts include: 2-iodo-1,4-benzoquinone, 2-chloro-6-iodo-1,4-benzoquinone, 2-bromo-6-iodo-1,4-benzoquinone, 2,3-diiodo-1,4-benzoquinone, and 2,6-diiodo-1,4-benzoquinone.

[0088] Step (2), Adjust pH: Adjust the standard solution to pH 0;

[0089] Step (3), solid phase extraction: The pH-adjusted standard solution is passed through an activated Oasis MAX solid phase extraction column (activated sequentially with 6 mL of methanol and 6 mL of ultrapure water) at a flow rate of 4 mL / min, and eluted with 3 mL of methanol containing 4 v / v% formic acid to obtain the eluent.

[0090] Step (4), Nitrogen blowing concentration: Blow nitrogen into the eluent to 0.2 mL to obtain the concentrate;

[0091] Step (5) Dilution and filtration: Add 0.3 mL of acetonitrile to the concentrate, and before detection, add 0.5 mL of ultrapure water for dilution and then filter through a 0.45 μm filter membrane.

[0092] Step (6), Detection: The samples were detected using HPLC-MS / MS. During detection, the sample solutions were tested using mobile phase I and mobile phase III respectively. The detection data of mobile phase I were used as the result data for 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, and 3-bromo-5-iodosalicylic acid. The detection data of mobile phase III were used as the result data for iodobenzoquinones. Then, the recovery rate, detection limit, and quantitation limit were calculated. The results are shown in Table 4.

[0093] Example 4: Recovery and detection limits of iodophenols, iodonitrophenols, iodohydroxybenzaldehydes, iodohydroxybenzoic acids, and iodoacetic acids as disinfection byproducts determined by solid-phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS).

[0094] When conducting recovery tests, two concentration gradients were selected, and each substance was prepared into two portions with concentrations of 5 ng / L and 50 ng / L, respectively.

[0095] The solid-phase extraction method is applied to disinfection byproducts of iodophenols, iodonitrophenols, iodohydroxybenzaldehydes, iodohydroxybenzoic acids, and iodoacetic acids, including the following steps:

[0096] Step (1) Preparation of standard solution: Prepare 1L of standard solution containing 13 iodophenols, 2 iodonitrophenols, 4 iodohydroxybenzaldehydes, 3 iodohydroxybenzoic acids and 4 iodoacetic acid disinfection byproducts; wherein, the 13 iodophenol disinfection byproducts are: 4-iodophenol, 2-iodophenol, 2,4,6-triiodophenol, 2-chloro-4-iodophenol, 2,6-diiodo-4-chlorophenol, 2-iodo-4-bromophenol, 2,6-diiodo-4-bromophenol, 2-chloro-6-iodophenol, 2-bromo-4-iodophenol, 2,6-dichloro-4-iodophenol, 2-iodo-4-chlorophenol, 2,4-dibromo-4-iodophenol, 2,4-dichloro-6-iodophenol;

[0097] The two iodonitrophenol disinfection byproducts are 4-iodo-2-nitrophenol and 2-iodo-4-nitrophenol.

[0098] The four iodohydroxybenzaldehyde disinfection byproducts are: 3,5-diiodo-4-hydroxybenzaldehyde, 3-iodo-4-hydroxybenzaldehyde, 3-bromo-5-chloro-salicylaldehyde, and 3-bromo-5-iodo-4-hydroxybenzaldehyde.

[0099] The three iodohydroxybenzoic acid disinfection byproducts are: 3-iodo-4-hydroxybenzoic acid, 5-iodosalicylic acid, and 3-bromo-5-iodo-4-hydroxybenzoic acid;

[0100] The four iodoacetic acid disinfection byproducts are: monoiodoacetic acid, chloroiodoacetic acid, bromoiodoacetic acid, and diiodoacetic acid. Step (2): Adjust the pH of the standard solution to 6.

[0101] Step (3), solid phase extraction: The pH-adjusted standard solution is passed through an activated Oasis MAX solid phase extraction column (activated sequentially with 6 mL of methanol and 6 mL of ultrapure water) at a flow rate of 4 mL / min, and eluted with 3 mL of methanol containing 8 v / v% formic acid to obtain the eluent.

[0102] Step (4), Nitrogen blowing concentration: Blow nitrogen into the eluent to 0.2 mL to obtain the concentrate;

[0103] Step (5) Dilution and filtration: Add 0.3 mL of acetonitrile to the concentrate, and before detection, add 0.5 mL of ultrapure water for dilution and then filter through a 0.45 μm filter membrane to obtain the sample solution.

[0104] Step (6), Detection: The sample solution was detected using HPLC-MS / MS. During the detection, the sample solution was tested using mobile phase I and mobile phase II respectively. The detection data of mobile phase I was used as the result data for iodophenols, iodonitrophenols, iodohydroxybenzaldehydes, and iodohydroxybenzoic acids, while the detection data of iodoacetic acid disinfection byproducts was used as the result data. Then, the recovery rate, detection limit, and quantitation limit were calculated. The results are shown in Table 5.

[0105]

[0106]

[0107] As can be seen from the results in Tables 4 and 5, the recovery rates of disinfection byproducts such as iodophenols, iodonitrophenols, iodohydroxybenzaldehydes, iodohydroxybenzoic acids, iodobenzoquinones, and iodoacetic acids are all higher than 70%.

[0108] The results of Examples 3 and 4 show that the recoveries of all polar iodinated disinfection byproducts were higher than 70%, with detection limits of 0.04-0.20 ng / L and quantitation limits of 0.13-0.64 ng / L for most substances. Furthermore, compared to patent CN114113370A, this method uses less sample and eluent volume, outperforming most reported methods. Therefore, this solid-phase extraction-liquid chromatography-mass spectrometry (SPME-MS) method can be applied to the simultaneous analysis of iodophenols, iodonitrophenols, iodohydroxybenzaldehydes, iodohydroxybenzoic acids, iodobenzoquinones, and iodoacetic acids as disinfection byproducts.

[0109] The mass spectrometry parameters of the 35 polar iodinated disinfection byproducts detected in Examples 3 and 4 are shown in Table 1.

[0110] Example 5: Case Study of Drinking Water Sample Analysis

[0111] Taking water samples collected from 8 districts in Nanjing and 7 districts in Shanghai ("AH" represents Nanjing water sample, "IO" represents Shanghai water sample) as an example, this paper details an analytical method for polar iodinated disinfection byproducts in drinking water. After collection, the water samples were immediately sent to the laboratory. Ascorbic acid was added to remove residual chlorine, and the samples were stored at 4°C. Before processing, the samples were removed and brought to room temperature, and then the following procedures were performed:

[0112] Step 1, Filtration: Take two 1L water samples that have been brought to room temperature and filter them through a 0.45μm filter membrane.

[0113] Step 2, pH adjustment: Adjust the pH of the two filtered water samples to 0 and 6 respectively;

[0114] Step 3, Solid-phase extraction: Two pH-adjusted water samples were passed through an activated Oasis MAX solid-phase extraction column at a flow rate of 4 mL / min for adsorption. Then, they were eluted with methanol containing 4 v / v% formic acid and methanol containing 8 v / v% formic acid, respectively, to obtain an eluent containing polar iodinated disinfection byproducts.

[0115] Step 4, Nitrogen blowing concentration: The eluent containing polar iodine disinfection byproducts was concentrated to 0.2 mL by nitrogen blowing to obtain a concentrated solution.

[0116] Step 5, Dilution: Add 0.3 mL of acetonitrile to the concentrate, and then add 0.5 mL of ultrapure water to dilute before detection;

[0117] Step 6, filtration again: Filter the diluted solution again through a 0.45μm filter membrane to obtain the sample solution. At this time, there are 2 sample solutions, 1 corresponding to the water sample with pH 0 in step 2 and 1 corresponding to the water sample with pH 6 in step 2.

[0118] Step 7, Detection: Divide the sample solution corresponding to pH 0 in Step 2 into two portions again, and divide the sample solution corresponding to pH 6 in Step 2 into two portions again; now there are a total of four sample solutions. The first and second sample solutions are obtained by equally dividing the sample solution corresponding to pH 0 in Step 2; the third and fourth sample solutions are obtained by equally dividing the sample solution corresponding to pH 6 in Step 2. Analyze each of the four sample solutions using HPLC-MS / MS. The results are shown in [Figure showing results]. Figures 1-6 .

[0119] 1) The HPLC-MS / MS settings for the first sample solution are as follows:

[0120] The HPLC settings for the first sample solution are as follows:

[0121] Column type: X Select HSS T3 column (2.1×100mm, packing particle size 3.5μm, Waters); Column temperature: 40℃; Injection volume: 5μL; Mobile phase: ultrapure water as phase A, acetonitrile as phase B; Flow rate of mobile phase: 0.3mL / min. Gradient elution program: 0–1min, maintain 90% phase A; 1–12min, linear transition from 90% phase A to 10% phase A; 12–14min, maintain 10% phase A; 14–14.1min, rapid transition from 10% phase A to 90% phase A; 14.1–16min, maintain 90% phase A.

[0122] The mass spectrometry settings for the first sample solution are as follows:

[0123] MRM mode is used; collision activation dissociation pressure is 4 psi, curtain pressure is 40 psi, ion source gas pressure 1 and 2 are both 45 psi, and ion source temperature is 500℃.

[0124] The ESI negative ion mode was selected for detection; the settings for the ESI negative ion mode were: voltage -4500V, inlet potential -10V, and collision cell outlet potential -14V.

[0125] Processing of results for the first sample solution: The detection data of 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, and 3-bromo-5-iodosalicylic acid disinfection byproducts were taken from the detection data of the first sample solution as the result data.

[0126] 2) The HPLC-MS / MS settings for the second sample solution are the same as those for the first sample solution. The only difference is that the mobile phase for the second sample solution is: 0.1% formic acid solution as phase A and acetonitrile as phase B. All other parameters are the same as those for the first sample solution.

[0127] Processing of results for the second sample solution: The detection data of iodobenzoquinone disinfection byproducts were taken from the detection data of the second sample solution as the result data;

[0128] 3) The HPLC-MS / MS settings for the third sample solution are the same as those for the first sample solution.

[0129] Results processing for the third sample solution: The detection data of disinfection byproducts such as iodophenols, iodonitrophenols, iodohydroxybenzaldehydes, and iodohydroxybenzoic acids (excluding 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, and 3-bromo-5-iodosalicylic acid) were taken from the detection data of the third sample solution as the result data.

[0130] 4) The HPLC-MS / MS settings for the fourth sample solution were the same as those for the first sample solution, except that the gradient elution program for the fourth sample solution was as follows: 0-12 min, linear transition from 90% A phase to 10% A phase; 12-12.1 min, rapid transition from 10% A phase to 90% A phase; 12.1-15 min, maintaining 90% A phase.

[0131] Results processing for the fourth sample solution: The detection data of iodoacetic acid disinfection byproducts were taken from the detection data of the fourth sample solution as the result data;

[0132] Figure 1The results of the detection of iodophenol disinfection byproducts in Example 5 are shown in the figure. As can be seen from the figure, 11 iodophenol substances were detected, with concentrations ranging from 0.17 to 2.21 ng / L. 2,4,6-Triiodophenol was the main pollutant.

[0133] Figure 2 The results of the detection of iodonitrophenol disinfection byproducts in Example 5 are shown in the figure. It can be seen from the figure that three iodonitrophenol substances were detected, with a concentration range of 0.12-0.63 ng / L. 2,6-Diiodo-4-nitrophenol is the main pollutant.

[0134] Figure 3 The results of the detection of disinfection byproducts of iodohydroxybenzaldehyde in Example 5 are shown in the figure. It can be seen from the figure that three iodohydroxybenzaldehyde-like substances were detected, with a concentration range of 0.27-0.95 ng / L. 3,5-Diiodo-4-hydroxybenzaldehyde is the main pollutant.

[0135] Figure 4 The results of the detection of iodohydroxybenzoic acid disinfection byproducts in Example 5 are shown in the figure. As can be seen from the figure, four iodohydroxybenzoic acid substances were detected, with a concentration range of 0.32-1.52 ng / L. 3,5-Diiodosalicylic acid was the main pollutant.

[0136] Figure 5 The results of the detection of iodobenzoquinone disinfection byproducts in Example 5 are shown in the figure. It can be seen from the figure that five iodobenzoquinone substances were detected, with a concentration range of 0.27-6.25 ng / L. 2-bromo-6-iodo-1,4-benzoquinone was the main pollutant.

[0137] Figure 6 The results of the detection of iodoacetic acid disinfection byproducts in Example 5 are shown in the figure. As can be seen from the figure, four iodoacetic acid substances were detected, with concentrations ranging from 0.09 to 4.69 ng / L. Bromoiodoacetic acid was the main pollutant.

[0138] In summary, from Figures 1-6 The results show that a total of 30 polar iodine-based disinfection byproducts were detected in this embodiment.

[0139] The embodiments described above are merely preferred embodiments of the present invention, and not an exhaustive list of all possible implementations of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A method for analyzing polar iodinated disinfection byproducts in drinking water, characterized in that, Includes the following steps: Step 1, Filtration: Filter the water sample to be tested through a filter membrane; Step 2, Adjust pH: Adjust the pH of the filtered water sample to 0 and / or 6; Step 3, Solid-phase extraction: The pH-adjusted water sample is adsorbed through an activated solid-phase extraction column, and then eluted with an eluent to obtain an eluent solution containing polar iodine disinfection byproducts. Step 4, nitrogen blowing concentration: The elution solution containing polar iodine disinfection byproducts is concentrated by nitrogen blowing to obtain a concentrated solution; Step 5, Dilution: Add acetonitrile to the concentrate and dilute with ultrapure water before testing; Step 6, filtration again: Filter the diluted solution through a filter membrane again to obtain the sample solution; Step 7, Liquid chromatography-mass spectrometry: The sample solution was analyzed using HPLC-MS / MS.

2. The analytical method for polar iodine disinfection byproducts in drinking water according to claim 1, characterized in that, The filter membrane used in steps 1 and 6 is a 0.4-0.5 μm filter membrane.

3. The analytical method for polar iodine disinfection byproducts in drinking water according to claim 1, characterized in that, In step 1, the water sample to be tested is divided into two identical portions. After filtration, the pH is adjusted to 0 and 6 respectively, and the polar iodine disinfection byproducts in the water sample are detected.

4. The analytical method for polar iodine disinfection byproducts in drinking water according to claim 3, characterized in that, The polar iodinated disinfection byproducts in water samples include one or more of the following: iodoacetic acid, iodophenol, iodonitrophenol, iodohydroxybenzaldehyde, iodohydroxybenzoic acid, and iodobenzoquinone.

5. The analytical method for polar iodinated disinfection byproducts in drinking water according to claim 4, characterized in that, Iodoacetic acid disinfection byproducts include one or more of monoiodoacetic acid, chloroiodoacetic acid, bromoiodoacetic acid, and diiodoacetic acid; Iodinated phenolic disinfection byproducts include one or more of the following: 4-iodophenol, 2-iodophenol, 2,4,6-triiodophenol, 2-chloro-4-iodophenol, 2,6-diiodo-4-chlorophenol, 2-iodo-4-bromophenol, 2,6-diiodo-4-bromophenol, 2-chloro-6-iodophenol, 2-bromo-4-iodophenol, 2,6-dichloro-4-iodophenol, 2-iodo-4-chlorophenol, 2,4-dibromo-4-iodophenol, and 2,4-dichloro-6-iodophenol. Iodinated nitrophenol disinfection byproducts include one or more of 2,6-diiodo-4-nitrophenol, 4-iodo-2-nitrophenol, and 2-iodo-4-nitrophenol. Iodohydroxybenzaldehyde disinfection byproducts include one or more of 3,5-diiodo-4-hydroxybenzaldehyde, 3-iodo-4-hydroxybenzaldehyde, 5-iodosalicylic acid aldehyde, and 3-bromo-5-iodo-4-hydroxybenzaldehyde; Iodohydroxybenzoic acid disinfection byproducts include one or more of the following: 3,5-diiodosalicylic acid, 3-iodo-4-hydroxybenzoic acid, 5-iodosalicylic acid, 3-iodo-5-bromosalicylic acid, 3-bromo-5-iodosalicylic acid, and 3-bromo-5-iodo-4-hydroxybenzoic acid. Iodobenzoquinone disinfection byproducts include one or more of the following: 2-iodo-1,4-benzoquinone, 2-chloro-6-iodo-1,4-benzoquinone, 2-bromo-6-iodo-1,4-benzoquinone, 2,3-diiodo-1,4-benzoquinone, and 2,6-diiodo-1,4-benzoquinone.

6. The analytical method for polar iodinated disinfection byproducts in drinking water according to claim 1 or 3, characterized in that, When the pH value is adjusted to 0 in step 2, the polar iodinated disinfection byproducts detected in the water sample include one or more of the following: 2,6-diiodo-4-nitrophenol, 3,5-diiodosalicylic acid, 3-iodo-5-bromosalicylic acid, 3-bromo-5-iodosalicylic acid, and iodobenzoquinone disinfection byproducts. When the pH value is adjusted to 6 in step 2, the polar iodinated disinfection byproducts detected in the water sample include one or more of the following: iodoacetic acid, iodophenol, iodonitrophenol, iodohydroxybenzaldehyde, and iodohydroxybenzoic acid.

7. The analytical method for polar iodinated disinfection byproducts in drinking water according to claim 1, characterized in that, In step 3, an Oasis MAX solid-phase extraction column was used. The activation method of the solid-phase extraction column was as follows: methanol and ultrapure water were passed through the solid-phase extraction column in sequence to activate it.

8. The method for analyzing polar iodinated disinfection byproducts in drinking water according to claim 1, characterized in that, In step 3, during adsorption, the flow rate of the water sample through the solid-phase extraction column is 3-5 mL / min; the eluent used is methanol containing 4-8 v / v% formic acid.

9. The method for analyzing polar iodinated disinfection byproducts in drinking water according to claim 1, characterized in that, In step 4, the temperature of nitrogen blowing concentration is controlled at <30℃; in step 5, during dilution, the volume ratio of concentrate, acetonitrile and ultrapure water is 1:(1~2):(2~3).

10. The analytical method for polar iodinated disinfection byproducts in drinking water according to claim 1, characterized in that, In step 7, when using HPLC-MS / MS to detect the sample solution, for the sample solution in step 2 with the pH adjusted to 6, mobile phase I and mobile phase II are used for detection, respectively; for the sample solution in step 2 with the pH adjusted to 0, mobile phase I and mobile phase III are used for detection, respectively. When using HPLC-MS / MS to analyze sample solutions, the HPLC settings are as follows: Both mobile phase I and mobile phase II consist of ultrapure water as phase A and acetonitrile as phase B; mobile phase III consists of a formic acid solution with a volume concentration of 0.05–0.15% as phase A and acetonitrile as phase B; the flow rates of both mobile phase I and mobile phase III are 0.2–0.4 mL / min. The gradient elution program for mobile phases I and III is as follows: 0-1 min, maintain 90% A phase constant; 1-12 min, linearly change from 90% A phase to 10% A phase; 12-14 min, maintain 10% A phase constant; 14-14.1 min, rapidly change from 10% A phase to 90% A phase; 14.1-16 min, maintain 90% A phase constant. The flow rate of mobile phase II is 0.4–0.6 mL / min; the gradient elution program of mobile phase II is as follows: 0–12 min, linearly changing from 90% phase A to 10% phase A; 12–12.1 min, rapidly changing from 10% phase A to 90% phase A; 12.1–15 min, maintaining 90% phase A. When using HPLC-MS / MS to analyze sample solutions, the mass spectrometry settings are as follows: The MRM mode is adopted; the collision activation dissociation gas pressure is 3-5 psi, the curtain gas pressure is 35-45 psi, the pressure of ion source gas 1 and 2 is 40-50 psi, and the ion source temperature is 450-550℃. The detection was performed using ESI negative ion mode. The settings for ESI negative ion mode were: voltage -4300 to -4600V, inlet potential -8 to -12V, and collision cell outlet potential -13 to -16V.

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