Method for detecting neonicotinoid compounds in sediment

Abstract

The invention discloses a method for detecting neonicotinoid compounds in sediments, which comprises the following steps: S100, drying, grinding and sieving a sediment sample, uniformly mixing the sediment sample with diatomite, extracting by using a methanol-acetonitrile mixed solvent as an extracting agent and adopting an accelerated solvent extraction method, and concentrating an extracting solution to be purified; s200, purifying the concentrated extract by using a solid-phase extraction column, collecting the eluent, concentrating, and filtering to obtain a sample to be detected; and S300, analyzing the concentration of the neonicotinoid compounds in the sample to be detected by using high performance liquid chromatography-tandem triple quadrupole mass spectrometry. The method is simple to operate, rapid and time-saving, has relatively good sensitivity and precision, and can be applied to detection of river sediments in a chemical aggregation area.

Description

Technical Field

[0001] This article relates to the field of environmental pollution assessment technology, and in particular to a method for detecting neonicotinoid compounds in sediments. Background Technology

[0002] Neonicotinic acid compounds (NNIs) are the fourth generation of pesticides after organophosphates, carbamates, and pyrethroids. Due to their high efficiency, low toxicity, and broad spectrum, they have become the most widely used class of pesticides worldwide. However, because NNIs can harm non-target organisms and even adversely affect immune signaling in human cell lines, and because they are used in large quantities, have low volatility, high water solubility, and long half-lives in sediments, they are widely present in soil, water, and air, and have attracted widespread attention in recent years.

[0003] Currently, there are numerous methods for detecting non-nitrogenous compounds (NNIs) in aquatic environments, but methods for analyzing NNIs in sediments are rarely reported. Due to the complex matrix and low concentration of NNIs in sediments, sample extraction, purification, and analysis are crucial for the detection of target compounds. Current commonly used extraction methods for NNIs in sediment samples suffer from low extraction efficiency. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing methods for detecting neonicotinoids in sediments by providing a rapid method for the simultaneous detection of eight neonicotinoids (dinotefuran, acetamiprid, thiamethoxam, thiamethoxam, imidacloprid, chlorthiazoline, acetamiprid, and thiamethoxam) in sediments. This method is simple, rapid, and time-saving, and has better sensitivity and precision compared to other similar methods. It can be applied to the detection of neonicotinoids in river sediments in chemical industrial clusters.

[0005] To achieve the above objectives, embodiments of this application provide a method for detecting neonicotinoid compounds in sediments, comprising the following steps: S100. After the sediment sample is dried, ground and sieved, it is mixed with diatomaceous earth and extracted using a methanol-acetonitrile mixed solvent as the extractant. The extract is then concentrated and purified. S200. The concentrated extract is purified using a solid-phase extraction column, the eluent is collected, concentrated, and filtered to obtain the sample to be tested; S300. The concentration of neonicotinoid compounds in the sample was analyzed using high performance liquid chromatography-tandem triple quadrupole mass spectrometry.

[0006] Among them, neonicotinoid compounds are selected from one, more or all of the following: fipronil, acetamiprid, thiamethoxam, thiamethoxam, imidacloprid, chlorthiacloprid, acetamiprid and thiamethoxam.

[0007] The beneficial effects of the technical solution in this application include: The method for detecting neonicotinoids in sediments provided in this application utilizes accelerated solvent extraction combined with solid-phase extraction (ASE-SPE) pretreatment and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) detection. This method rapidly extracts NNIs from sediments, enabling rapid and efficient simultaneous detection of eight NNIs in the sediment sample. The method is simple, rapid, accurate, and allows for large-scale detection of target analytes. It also exhibits low limits of detection and quantitation, high recovery, and stable detection method, largely unaffected by the matrix. Specifically, when applied to river sediment samples from a chemical industrial cluster, the method achieved average recoveries of 88.5%–104.6% for the eight target NNIs compounds, with relative standard deviations of 4.4%–9.7% (n=3), and a method detection limit of 0.1 ng·g⁻¹. -1 Up to 0.7 ng·g -1 The limit of quantitation is 0.4 ng·g. -1 Up to 2.8 ng·g -1 When this method was applied to sediment samples from the Yangtze River Basin, the average recoveries of eight target NNIs compounds ranged from 91.3% to 105.4%, with relative standard deviations of 5.2% to 8.3%, and the method detection limits were 0.1 ng·g. -1 Up to 0.7 ng·g -1 The limit of quantitation is 0.4 ng·g. -1 Up to 2.8 ng·g -1 The study also detected eight neonicotinoid compounds at concentrations ranging from 0 to 6.9 ng / g. -1 The matrix effect ranged from 83.5% to 108.4%, validating the applicability of this method for analyzing neonicotinoid compounds in sediments.

[0008] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0009] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0010] Figure 1 This is a flowchart of a method for detecting neonicotinoid compounds in sediments according to embodiments of this application; Figure 2The following mobile phases were used for Comparative Example 2 of this application (a: pure water-acetonitrile, b: ultrapure water-methanol, c: 0.1% formic acid solution-methanol, d: 0.1% formic acid solution + 2 mmol·L⁻¹). -1 Ammonium acetate-methanol, e: 0.1% formic acid solution + 5 mmol·L⁻¹ -1 The response value of the target compound (ammonium acetate-methanol); Figure 3 The total ion chromatogram of eight neonicotinoid compounds (1: fipronil, 2: acetamiprid, 3: thiamethoxam, 4: thiamethoxam, 5: imidacloprid, 6: chlorothiazoline, 7: acetamiprid, 8: thiamethoxam) according to Example 1 of this application. Detailed Implementation

[0011] This application describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features have been shown and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature of any embodiment may be used in combination with any other feature in any other embodiment, or may substitute for any other feature in any other embodiment.

[0012] In a first aspect, this application provides a method for detecting neonicotinoid compounds in sediments, comprising the following steps: S100. After the sediment sample is dried, ground and sieved, it is mixed with diatomaceous earth and extracted using a methanol-acetonitrile mixed solvent as the extractant. The extract is then concentrated and purified. S200. The concentrated extract is purified using a solid-phase extraction column, the eluent is collected, concentrated, and filtered to obtain the sample to be tested; S300. The concentration of neonicotinoid compounds in the sample was analyzed using high performance liquid chromatography-tandem triple quadrupole mass spectrometry.

[0013] In one exemplary embodiment, the sediment is an aquatic sediment, such as river sediments from a chemical industrial cluster, sediments from the Yangtze River basin, sediments from the Yellow River basin, or any other natural aquatic sediment.

[0014] In one exemplary embodiment, the neonicotinoid compound is selected from one, more, or all of the following: fipronil, acetamiprid, thiamethoxam, thiamethoxam, imidacloprid, chlorthiazoline, acetamiprid, and thiamethoxam.

[0015] In step S100, the drying process can be any method that removes moisture from the sediment sample without affecting the detection of the analytes in the sample. In an exemplary embodiment, the drying process can be high-temperature drying or freeze-drying.

[0016] In step S100, grinding and sieving are used to reduce particle size, improve subsequent extraction efficiency, control particle uniformity, and avoid systematic errors caused by loss of material on the sieve. In an exemplary embodiment, sieving can be done through a 100-mesh sieve.

[0017] In one exemplary embodiment, in step S100, the mass ratio of the dried, ground, and sieved sediment sample to diatomaceous earth is 1:5 to 1:15, optionally 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15, and more preferably 1:10. If the amount of diatomaceous earth used is too low (e.g., below 1:5), the sample will be unevenly dispersed and prone to clumping, which may lead to a decrease in extraction efficiency; if the amount used is too high (e.g., above 1:15), the sample will be unnecessarily diluted, and the load on subsequent solid-phase extraction and other steps will be increased.

[0018] In one exemplary embodiment, in step S100, the volume ratio of methanol to acetonitrile in the extractant is 1:(0.8 to 1.2), optionally 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, and more preferably 1:1. In one exemplary embodiment, the ratio of the dried, ground, and sieved sediment sample to the extractant is 5 g:(20 mL to 30 mL).

[0019] In one exemplary embodiment, in step S100, the accelerated solvent extraction method uses an extraction temperature of 80°C to 120°C, optionally 80°C, 100°C, or 120°C, and more preferably 100°C. In another exemplary embodiment, in step S100, the accelerated solvent extraction method uses an extraction pressure of 1400 psi to 1600 psi, for example, 1500 psi.

[0020] In one exemplary embodiment, in step S100, the accelerated solvent extraction method includes the following extraction procedure: heating for 5 minutes, static extraction for 5 minutes, nitrogen purging for 100 seconds, and static cycling 1 to 3 times, optionally 2 or 3 times.

[0021] In one exemplary embodiment, in step S100, the extract is concentrated to 1 mL to 2 mL.

[0022] In one exemplary embodiment, in step S200, the solid phase extraction column can be selected from HLB extraction columns, C18 columns, and mixed cation exchange columns, and can be selected as an HLB extraction column.

[0023] In one exemplary embodiment, in step S200, the eluent used in the purification is a methanol-acetonitrile mixed solvent, wherein the volume ratio of methanol to acetonitrile is 1:(0.8 to 1.2), optionally 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, and more preferably 1:1. In one exemplary embodiment, before elution, a solid-phase extraction column activation step is further included, comprising activating the solid-phase extraction column sequentially with methanol and ultrapure water. In one exemplary embodiment, after the solid-phase extraction column is activated, the extract is passed through the activated extraction column and then dried under negative pressure using a vacuum pump, and the extraction column is eluted with an eluent.

[0024] In this application, concentration can be achieved using any method that removes the solvent without affecting the detection of the analyte, such as nitrogen blowing concentration. The eluent can be concentrated to a suitable volume for further operations, for example, 1 mL to 2 mL.

[0025] In one exemplary embodiment, in step S200, the filtration step may be performed using a 0.22μm organic phase needle filter.

[0026] In one exemplary embodiment, in step S300, the chromatographic conditions in the high-performance liquid chromatography-tandem triple quadrupole mass spectrometry method include: Chromatographic column: C18 column (e.g., Agilent ZORBAX Eclipse Plus C18 column, 100 × 2.1 mm, 1.8 µm); mobile phase A: ultrapure water containing 0.1%, v / v formic acid + 2 mmol / L to 5 mmol / L ammonium acetate; mobile phase B: methanol; gradient elution.

[0027] In an exemplary embodiment, in step S300, the chromatographic conditions of the high-performance liquid chromatography-tandem triple quadrupole mass spectrometry method further include: flow rate: 0.3 mL / min; injection volume: 2 μL; column temperature: 40℃; gradient elution program: 0 min, 10% mobile phase B; 0 min to 5 min, 10% mobile phase B to 45% mobile phase B; 5 min to 9 min, 45% mobile phase B to 80% mobile phase B; 9 min to 9.1 min, 80% mobile phase B to 10% mobile phase B; 9.1 min to 10.1 min, 10% mobile phase B.

[0028] In an exemplary embodiment, in step S300, the mass spectrometry conditions in the high performance liquid chromatography-tandem triple quadrupole mass spectrometry method include: electrospray ionization source, positive ion mode (ESI+); ion source spray voltage: 3500 V; ion source temperature: 300 °C; nebulizing gas: 30 psi; drying gas temperature: 325 °C; sheath gas temperature: 350 °C; drying gas flow rate: 6 L / min; sheath gas flow rate: 11 L / min.

[0029] In one exemplary embodiment, in step S300, the concentration of neonicotinoid compounds in the sample to be tested can be quantified using an internal standard method. The internal standard is selected from one or more of acetamiprid-d3, thiamethoxam-d3, and imidacloprid-d4, and can be selected as imidacloprid-d4.

[0030] In one exemplary embodiment, this application provides a method for detecting neonicotinoid compounds in sediments, wherein the neonicotinoid compounds are selected from one, more, or all of the following: dinotefuran, acetamiprid, thiamethoxam, imidacloprid, chlorpyrifos, acetamiprid, and thiamethoxam. The method includes the following steps: S001. Prepare a standard solution containing the neonicotinoid compound to be detected, and use imidacloprid-d4 as an internal standard; S100. The sediment sample is dried, ground, and sieved. After being mixed with diatomaceous earth, it is extracted using a methanol-acetonitrile mixed solvent with a volume ratio of 1:1 as the extractant. The extract is then concentrated and purified. The extraction conditions for the accelerated solvent extraction method are as follows: extraction temperature of 80℃ to 120℃ (optional 100℃), extraction pressure of 1400 psi to 1600 psi (optional 1500 psi), and extraction program of: heating for 5 min, static extraction for 5 min, nitrogen purging for 100 s, and static circulation 2 or 3 times. S200. The concentrated extract was purified using an HLB solid-phase extraction column, with a 1:1 methanol-acetonitrile mixed solvent as the eluent. The eluent was collected and concentrated, and after adding an internal standard, it was filtered to obtain the sample to be tested. S300. The concentration of neonicotinoid compounds in standard solutions and test samples was analyzed using high performance liquid chromatography-tandem triple quadrupole mass spectrometry. The chromatographic conditions included: column: C18 column; mobile phase A: ultrapure water containing 0.1%, v / v formic acid + 2 mmol / L to 5 mmol / L ammonium acetate; mobile phase B: methanol; flow rate: 0.3 mL / min; column temperature: 40℃; gradient elution program: 0 min, 10% mobile phase B; 0 min to 5 min, 10% mobile phase B to 45% mobile phase B; 5 min to 9 min, 45% mobile phase B to 80% mobile phase B; 9 min to 9.1 min, 80% mobile phase B to 10% mobile phase B; 9.1 min to 10.1 min, 10% mobile phase B. Mass spectrometry conditions included: electrospray ionization source, positive ion mode (ESI+); ion source spray voltage: 3500 V; ion source temperature: 300 °C; nebulizer gas: 30 psi; dryer gas temperature: 325 °C; sheath gas temperature: 350 °C; dryer gas flow rate: 6 L / min; sheath gas flow rate: 11 L / min. S400. Perform linear regression on the ratio of the mass spectrometric peak area of ​​the analyte to the internal standard in the standard solution and the mass concentration of the analyte to obtain the linear equation; S500. Substitute the mass spectrum peak area ratio of the analyte to the internal standard in the sample into the linear equation obtained in step S400 to calculate the concentration of neonicotinoids in the sample.

[0031] The embodiments of this application are described in detail below. The specific implementation of this application will be further explained in detail below with reference to the accompanying drawings and examples, but the implementation and protection of this application are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0032] Unless otherwise specified, all materials and reagents used in the embodiments of this invention can be purchased commercially. Information on the reagents and instruments used in the following embodiments is as follows: The following standards were purchased from Tanmo Quality Inspection Technology Co., Ltd.: fipronil, acetamiprid, thiamethoxam, thiamethoxam, imidacloprid, chlorthiacloprid, acetamiprid, mixed thiamethoxam standards, and internal standard imidacloprid-d4.

[0033] Rapid solvent extraction system: Thermo Fisher (USA), model: Dionex ASE350.

[0034] Fully automated sample concentrator: Biotage Turbovap (Sweden).

[0035] High performance liquid chromatography-triple quadrupole mass spectrometry system: Agilent 1290-6460 (USA).

[0036] Example 1 This embodiment uses blank garden soil as the experimental subject. Through spiked recovery experiments, eight neonicotinoid compounds (dinotefuran (1), acetamiprid (2), thiamethoxam (3), thiamethoxam (4), imidacloprid (5), chlorothalonil (6), acetamiprid (7), and thiamethoxam (8)) were extracted from the sediment using accelerated solvent extraction (ASE). Ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UHPLC-MS / MS) was then performed to evaluate the accuracy of the method for detecting neonicotinoid compounds in sediment, using the recovery rate as the indicator. Specifically, this includes: (1) Preparation of standard solutions: Using methanol-acetonitrile mixed solvent (1:1, v / v) as solvent, a series of mixed standard solutions containing the above 8 neonicotinoid compounds were prepared. The concentrations of each neonicotinoid compound standard substance in the series of mixed standard solutions were 0.5, 1, 5, 10, 20, 50 and 100 µg·L, respectively. -1 An isotope internal standard was added to each series of mixed standard solutions, with a concentration of 50 µg·L⁻¹. -1 .

[0037] (2) Using blank garden soil as the experimental subject, the amount of standard substance added was 10 ng·g -1 Spiked recovery tests were conducted under the following conditions: Spiked garden soil was freeze-dried, ground, and sieved through a 100-mesh sieve. 5 g of garden soil was weighed and mixed with 50 g of diatomaceous earth, then placed in the extraction chamber of a rapid solvent extractor for extraction. Extraction conditions were: extractant: methanol:acetonitrile (1:1, v / v); temperature: 80 ℃, 100 ℃, or 120 ℃; pressure: 1500 psi; heating for 5 min; static extraction for 5 min; nitrogen purging for 100 s; static circulation 1, 2, or 3 times (extraction conditions are shown in Table 1). The extract was concentrated to 1 mL using a fully automated sample concentrator (BiotageTurbovap) and then purified. The experiment was repeated 3 times.

[0038] (3) The concentrated extract was purified using an HLB solid-phase extraction column. The specific steps included: activating the HLB extraction column with 10 mL of methanol and 10 mL of ultrapure water in sequence; passing the concentrated extract through the activated HLB extraction column and then drying it under vacuum pressure; eluting the HLB extraction column with 7 mL of methanol:acetonitrile (1:1, v / v) solution; collecting the eluent and concentrating it to 1 mL by nitrogen blowing; adding an internal standard and filtering it with a 0.22 μm organic phase needle filter to obtain the sample to be tested.

[0039] (4) The concentration of neonicotinoid compounds in the obtained samples was analyzed by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UPLC-MS / MS); the detection conditions of UPLC-MS / MS are as follows: UPLC conditions: Chromatograph: Agilent 1290-6460; Column: Agilent ZORBAX Eclipse plus-C18 column (100×2.1 mm, 1.8 µm); Column temperature: 40 ℃; Injection volume: 2 μL; Mobile phase A: ultrapure water containing 0.1%, v / v formic acid + 2 mmol / L ammonium acetate; Mobile phase B: methanol; Flow rate: 0.3 mL / min; Injection volume: 2 μL; Gradient elution: 0 min, 10% B; 0–5 min, 10% B–45% B; 5–9 min, 45% B–80% B; 9–9.1 min, 80% B–10% B; 9.1–10.1 min, 10% B; MS / MS conditions: Electrospray ionization source: Multiple reaction monitoring positive ion mode (ESI+); Ion source spray voltage: 3500 V; Ion source temperature: 300 °C; Nebulizer gas: 30 psi; Drying gas temperature: 325 °C; Sheath gas temperature: 350 °C; Drying gas flow rate: 6 L / min; Sheath gas flow rate: 11 L / min; The retention times and mass spectrometry parameters of specific target compounds are shown in Table 1.

[0040] Table 1 Mass spectrometry parameters of the target compound

[0041] * indicates a quantitative ion.

[0042] (5) The ratio of the mass spectrometric peak area (Y) of the analyte to the internal standard in the standard solution to the mass concentration (X, µg·L⁻¹) of the analyte. -1 Perform linear regression to obtain the linear equation and correlation coefficient (r). 2 ).

[0043] (6) Substitute the mass spectrum peak area ratio (Y) of the analyte to the internal standard in the blank garden soil and spiked garden soil samples into the above linear equation to calculate the recovery rate. The results are shown in Table 2.

[0044] Table 2 Recovery rate test results (n=3)

[0045] Method validation results showed that the spiked recoveries of this method for the eight target neonicotinoids ranged from 87.7% to 108.7%. This recovery range fully complies with the accuracy requirements of authoritative international and domestic standards such as the EU SANTE / 11312 / 2021 guideline (70%-120%) and the Chinese GB / T27417-2017 (80%-110%).

[0046] Comparative Example 1 This comparative example uses blank garden soil as the experimental object. Following the method in Example 1, eight neonicotinoid compounds (dinotefuran (1), acetamiprid (2), thiamethoxam (3), thiamethoxam (4), imidacloprid (5), chlorothalonil (6), acetamiprid (7), and thiamethoxam (8)) were extracted from the sediment using accelerated solvent extraction (ASE) with different extractants through a spiked recovery test. The extracted compounds were then analyzed by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UHPLC-MS / MS). The recovery rate was used as the indicator to evaluate the accuracy of the method for detecting neonicotinoid compounds in the sediment. The specific method is the same as in Example 1, except that the extraction conditions of the rapid solvent extractor used in step (1) are different. The extraction conditions for this comparative example are as follows: the extractant is methanol or acetonitrile, the temperature is 80 ℃, 100 ℃, or 120 ℃, the pressure is 1500 psi, heating for 5 min, static extraction for 5 min, nitrogen purging for 100 s, and static cycling 1, 2, or 3 times (the specific extraction conditions are shown in Table 3).

[0047] After concentration, the extract was purified according to the method in Example 1, and analyzed by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UPLC-MS / MS). The recovery results are shown in Table 3.

[0048] Table 3. Recovery rate test results (n=3)

[0049] The method validation results show that the recovery rate obtained by the extraction conditions of this comparative example is significantly worse than that of the extraction conditions of Example 1. Most of the conditions even fail to meet the accuracy requirements of the Chinese standard GB / T 27417-2017 (80%-110%).

[0050] Comparative Example 2 This comparative example uses different mobile phases to detect the response values ​​of ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UPLC-MS / MS) to eight target neonicotinoid compounds (fipronil (1), acetamiprid (2), thiamethoxam (3), thiamethoxam (4), imidacloprid (5), chlorothiazoline (6), acetamiprid (7) and thiamethoxam (8)).

[0051] The mobile phase system is as follows: Mobile phase system a: Mobile phase A: ultrapure water, Mobile phase B: acetonitrile; Mobile phase system b: Mobile phase A: ultrapure water, Mobile phase B: methanol; Mobile phase system c: Mobile phase A: Water containing 0.1% v / v formic acid; Mobile phase B: Methanol; Mobile phase system d: Mobile phase A: contains 0.1%, v / v formic acid + 2 mmol·L -1 Ammonium acetate in water; Mobile phase B: methanol; Mobile phase system e: Mobile phase A: contains 0.1%, v / v formic acid + 5 mmol·L -1 Ammonium acetate in water; Mobile phase B: methanol.

[0052] The specific method is as follows: Eight neonicotinic compounds were prepared into 10 µg·L⁻¹ solutions using a methanol-acetonitrile mixed solvent (1:1, v / v). -1 The standard solution was analyzed by UPLC-MS / MS. The UPLC-MS / MS detection conditions were the same as those in Example 1, except that the mobile phase was different.

[0053] The above solutions were analyzed by UPLC-MS / MS under each mobile phase system. Mass spectrometry detection was performed in multiple reaction monitoring positive ion mode, recording the peak area (response value) and peak shape of each compound's characteristic ion pair (parent ion → daughter ion). The results were obtained by comparing the values ​​obtained under each system. Figure 2 Chromatogram.

[0054] The results are as follows Figure 2 As shown, when using an aqueous solution-methanol system containing 0.1% formic acid and combined with 2 or 5 mmol / L ammonium acetate as the mobile phase, the target compound achieved optimal separation and response intensity. This is attributed to the volatile buffer system formed by formic acid and ammonium acetate, which effectively suppresses peak tailing in chromatography and provides a stable acidic environment for the analyte during mass spectrometry ionization, thereby significantly promoting and stabilizing its [M+H] content. + The formation of ions is the key reason for the improved response value. Given that the performance of the two ammonium acetate systems is comparable, the system with a lower ammonium acetate concentration (2 mmol / L) was ultimately chosen. This approach ensures excellent analytical performance while also adhering to the green analytical principle of reducing chemical usage and minimizing environmental impact.

[0055] Example 2 This embodiment uses river sediments from a chemical industrial cluster as samples to provide a method for detecting neonicotinoid compounds (dinotefuran (1), acetamiprid (2), thiamethoxam (3), thiamethoxam (4), imidacloprid (5), chlorothalonil (6), acetamiprid (7), and thiamethoxam (8)) in river sediments from a chemical industrial cluster. The specific steps are as follows: (1) Preparation of standard solutions: Using methanol-acetonitrile mixed solvent (1:1, v / v) as solvent, a series of mixed standard solutions containing the above 8 neonicotinoid compounds were prepared. The concentrations of each neonicotinoid compound standard substance in the series of mixed standard solutions were 0.5, 1, 5, 10, 20, 50 and 100 µg·L, respectively. -1 An isotope internal standard was added to each series of mixed standard solutions, with a concentration of 50 µg·L⁻¹. -1 .

[0056] (2) Sample preparation: (i) After freeze-drying, grinding, and sieving through a 100-mesh sieve, 5 g of sediment sample was weighed and mixed with 50 g of diatomaceous earth. The mixture was then placed in the extraction cell of a rapid solvent extractor for extraction. The extraction conditions were: extractant: methanol:acetonitrile (1:1, v / v), temperature: 100 ℃, pressure: 1500 psi, heating for 5 min, static extraction for 5 min, nitrogen purging for 100 s, and static circulation twice. The extract was concentrated to 1 mL using a fully automated sample concentrator (Biotage Turbovap) and then purified. (ii) The concentrated extract was purified using an HLB solid-phase extraction column. The specific steps included: activating the HLB extraction column sequentially with 10 mL of methanol and 10 mL of ultrapure water; passing the concentrated extract through the activated HLB extraction column and then drying it under vacuum; eluting the HLB extraction column with 7 mL of methanol:acetonitrile (1:1, v / v) solution; collecting the eluent and concentrating it to 1 mL by nitrogen blowing; adding an internal standard and filtering it using a 0.22 μm organic phase needle filter to obtain the sample to be tested.

[0057] (3) The standard solution and the sample to be tested were analyzed by UPLC-MS / MS. The detection conditions of UPLC-MS / MS were the same as in Example 1.

[0058] (4) The ratio of the mass spectrometric peak area (Y) of the analyte to the internal standard in the standard solution to the mass concentration (X, µg·L) of the analyte. -1 Perform linear regression to obtain the linear equation and correlation coefficient (r). 2 ).

[0059] (5) Prepare low (1 ng·g) -1 ), medium (10 ng·g-1 ), high (20 ng·g -1 Three blank spiked samples were prepared at each of the three levels, and the spiked recoveries (RE) and relative standard deviations (RSD) were calculated.

[0060] (6) Prepare a solution with a mass concentration of 1 ng·g -1 The sample was processed, and the sample was measured repeatedly n = 7 times. The standard deviation (S) of the 7 parallel determinations was calculated. t(6, 0.99) = 3.143. Therefore, the limit of detection (LOD) = 3.143 × S, and the limit of quantitation (LOQ) is 4 times the limit of detection.

[0061] (7) Actual sample verification: Three river sediment samples were collected from a chemical industrial cluster. After processing using the method in step (2), the samples were analyzed using UPLC-MS / MS using the method in step (3). The ratio of the mass spectrometry peak area (Y) of each analyte to the internal standard in the sample was substituted into the linear equation obtained in step (4) to obtain the content of eight neonicotinoid compounds in the sample.

[0062] (8) Results: The levels of the eight neonicotinoid compounds ranged from 0.5 to 100 µg·L⁻¹. -1 The internal linear relationship is good, r 2 All values ​​were greater than 0.999. When the standard dosage was 1 ng / g... -1 At that time, the RE was 88.5%~103%, and the RSD was 7.2%~9.7%; the addition amount was 10 ng·g -1 At that time, the RE was 94.3%~104.6%, and the RSD was 4.4%~7.7%; the addition amount was 20 ng·g -1 At that time, the RE was 91.6%–103.1%, and the RSD was 4.7%–7.6%. The method detection limit was 0.1–0.7 ng·g. -1 The limits of quantitation are 0.4–2.8 ng·g. -1 The specific parameters are shown in Table 4, indicating that the accuracy and precision of this method can meet the requirements for the detection of neonicotinoid compounds in sediments.

[0063] Table 4. Linear relationships, LOD, LOQ, RE, and contents of eight neonicotinoid compounds in river sediments of chemical industrial clusters (n=3)

[0064] ND indicates not detected.

[0065] Example 3 This embodiment uses sediment samples from the Yangtze River Basin as samples to provide a method for detecting neonicotinoid compounds such as dinotefuran (1), acetamiprid (2), thiamethoxam (3), thiamethoxam (4), imidacloprid (5), chlorothiazoline (6), acetamiprid (7), and thiamethoxam (8) in sediments from the Yangtze River Basin. The specific steps are as follows: (1) Preparation of standard solutions: Using methanol-acetonitrile mixed solvent (1:1, v / v) as solvent, a series of mixed standard solutions containing the above 8 neonicotinoid compounds were prepared. The concentrations of each neonicotinoid compound standard substance in the series of mixed standard solutions were 0.5, 1, 5, 10, 20, 50 and 100 µg·L, respectively. -1 An isotope internal standard was added to each series of mixed standard solutions, with a concentration of 50 µg·L⁻¹. -1 .

[0066] (2) The sample preparation method is the same as step (2) in Example 2.

[0067] (3) The standard solution and the sample to be tested were analyzed by UPLC-MS / MS. The detection conditions of UPLC-MS / MS were the same as in Example 1.

[0068] (4) The peak area ratio (Y) of the analyte to the internal standard in the standard solution and the mass concentration (X, µg·L) of the analyte -1 Perform linear regression to obtain the linear equation and correlation coefficient (r). 2 ).

[0069] (5) Prepare a solution with a concentration of 10 ng·g -1 For the blank spiked sample, calculate its spiked recovery (RE) and relative standard deviation (RSD).

[0070] (6) Prepare a solution with a mass concentration of 1 ng·g -1 The sample was processed, and the sample was measured repeatedly n = 7 times. The standard deviation (S) of the 7 parallel determinations was calculated. t(6, 0.99) = 3.143. Therefore, the limit of detection (LOD) = 3.143 × S, and the limit of quantitation (LOQ) is 4 times the limit of detection.

[0071] (7) Verification of actual samples: 36 river sediment samples were collected from the Yangtze River Basin. After processing by the method in step (2), the samples were analyzed by UPLC-MS / MS using the method in step (3). The mass spectrum peak area (Y) ratio of each analyte to the internal standard in the sample was substituted into the linear equation obtained in step (4) to obtain the content of 8 neonicotinoids in the sample, and the matrix effect (ME) of 8 neonicotinoids in the actual sample was calculated.

[0072] Matrix effect calculation: Obtain a blank sample free of the target neonicotinoid compounds and process it using the same rapid solvent extraction and solid-phase extraction column purification pretreatment methods as the actual sample to obtain a blank matrix extract. Preparation of standard solutions: Set A (pure solvent standard): Add the neonicotinoid compound mixed standard directly to a methanol-acetonitrile mixed solvent (1:1, v / v) as a pure solvent standard (neonicotinoid compound concentration: 10 µg·L⁻¹). -1 Set A (without matrix effect) measures the response value; Set B (matrix-spiked standard): A mixed standard of neonicotinoid compounds with the same concentration as Set A is added to the aforementioned prepared blank matrix extract as a matrix-spiked standard, and the response value is measured under matrix effect. The matrix effect is calculated based on the peak areas of the chromatographic peaks of Set B and Set A. Matrix effect = (peak area of ​​Set B / peak area of ​​Set A) × 100%. ME < 100%: indicates the presence of ion inhibition; ME > 100%: indicates the presence of ion enhancement.

[0073] (8) Results: The levels of the eight neonicotinoid compounds ranged from 0.5 to 100 µg·L⁻¹. -1 The internal linear relationship is good, r 2 All values ​​were greater than 0.999. The relative efficacy (RE) ranged from 91.3% to 105.4%, and the relative standard deviation (RSD) ranged from 5.2% to 8.3%. The limit of detection (LOD) was 0.1 to 0.7 ng / g. -1 The limit of quantitation is 0.4-2.8 ng·g. -1 Specific parameters are shown in Table 5. Both accuracy and precision meet the requirements for detecting neonicotinoid compounds in sediments.

[0074] Table 5. Linear relationships, LOD, LOQ, RE, and contents of eight neonicotinoids in sediments of the Yangtze River Basin (n=36)

[0075] ND indicates not detected.

[0076] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for detecting neonicotinoid compounds in sediments, characterized in that, Includes the following steps: S100. After the sediment sample is dried, ground and sieved, it is mixed with diatomaceous earth and extracted using a methanol-acetonitrile mixed solvent as the extractant. The extract is then concentrated and purified. S200. The concentrated extract is purified using a solid-phase extraction column, the eluent is collected, concentrated, and filtered to obtain the sample to be tested; S300. The concentration of neonicotinoid compounds in the sample was analyzed using high performance liquid chromatography-tandem triple quadrupole mass spectrometry.

2. The method according to claim 1, characterized in that, The sediments are aquatic sediments; Optionally, the aquatic sediments are selected from river sediments in chemical industrial clusters, sediments in the Yangtze River basin, sediments in the Yellow River basin, or sediments from other natural aquatic bodies.

3. The method according to claim 1, characterized in that, The neonicotinoid compounds are selected from one, more or all of the following: fipronil, acetamiprid, thiamethoxam, thiamethoxam, imidacloprid, chlorthiazoline, acetamiprid and thiamethoxam.

4. The method according to claim 1, characterized in that, In step S100: Drying is performed using high-temperature drying or freeze drying; and / or Sieving is performed through a 100-mesh sieve; and / or The mass ratio of the dried, ground and sieved sediment sample to diatomaceous earth is 1:5 to 1:15, and can be selected as 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, and can be further selected as 1:

10.

5. The method according to claim 1, characterized in that, In step S100: In the accelerated solvent extraction method, the volume ratio of methanol to acetonitrile in the extractant is 1:(0.8 to 1.2), optionally 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, and more preferably 1:1; and / or The ratio of the dried, ground, and sieved sediment sample to the extractant was 5 g: (20 mL to 30 mL).

6. The method according to claim 1, characterized in that, In step S100: In the accelerated solvent extraction method, the extraction temperature is 80℃ to 120℃, optionally 80℃, 100℃, or 120℃, and more preferably 100℃; and / or In the accelerated solvent extraction method, the extraction pressure is 1400 psi to 1600 psi, optionally 1500 psi; and / or In the accelerated solvent extraction method, the extraction procedure is as follows: heating for 5 min, static extraction for 5 min, nitrogen purging for 100 s, and static circulation 1 to 3 times, optionally 2 or 3 times; and / or Concentrate the extract to 1 mL to 2 mL.

7. The method according to claim 1, characterized in that, In step S200: The solid-phase extraction column is selected from HLB extraction columns, C18 columns, and mixed-type cation exchange columns, with HLB extraction columns being the preferred option; and / or The eluent used in the purification process is a methanol-acetonitrile mixed solvent, wherein the volume ratio of methanol to acetonitrile is 1:(0.8 to 1.2), optionally 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, and more preferably 1:1; and / or The filtration process was performed using a 0.22 μm organic phase needle filter.

8. The method according to claim 1, characterized in that, In step S300: In high-performance liquid chromatography-tandem triple quadrupole mass spectrometry, the chromatographic conditions include: Chromatographic column: C18 column (e.g., Agilent ZORBAX Eclipse Plus C18 column, 100 × 2.1 mm, 1.8 µm); mobile phase A: ultrapure water containing 0.1%, v / v formic acid + 2 mmol / L to 5 mmol / L ammonium acetate; mobile phase B: methanol; gradient elution; Optionally, the chromatographic conditions also include: flow rate: 0.3 mL / min; injection volume: 2 μL; column temperature: 40℃; gradient elution program: 0 min, 10% mobile phase B; 0 min to 5 min, 10% mobile phase B to 45% mobile phase B; 5 min to 9 min, 45% mobile phase B to 80% mobile phase B; 9 min to 9.1 min, 80% mobile phase B to 10% mobile phase B; 9.1 min to 10.1 min, 10% mobile phase B. In the high performance liquid chromatography-tandem triple quadrupole mass spectrometry method, the mass spectrometry conditions include: electrospray ionization source, positive ion mode; ion source spray voltage: 3500 V; ion source temperature: 300 ℃; nebulizer gas: 30 psi; drying gas temperature: 325 °C; sheath gas temperature: 350 °C; drying gas flow rate: 6 L / min; sheath gas flow rate: 11 L / min.

9. The method according to claim 8, characterized in that, In step S300, the concentration of neonicotinoid compounds in the sample to be tested is quantified using the internal standard method. The internal standard is selected from one or more of acetamiprid-d3, thiamethoxam-d3, and imidacloprid-d4, and imidacloprid-d4 can be selected as the internal standard.

10. The method according to any one of claims 1-9, characterized in that, The neonicotinoid compound is selected from one, more, or all of the following: dinotefuran, acetamiprid, thiamethoxam, imidacloprid, chlorpyrifos, acetamiprid, and thiamethoxam. The method includes the following steps: S001. Prepare a standard solution containing the neonicotinoid compound to be detected, and use imidacloprid-d4 as an internal standard; S100. The sediment sample is dried, ground, and sieved. After being mixed with diatomaceous earth, it is extracted using a methanol-acetonitrile mixed solvent with a volume ratio of 1:1 as the extractant. The extract is then concentrated and purified. The extraction conditions for the accelerated solvent extraction method are as follows: extraction temperature of 80℃ to 120℃ (optional 100℃), extraction pressure of 1400psi to 1600psi (optional 1500psi), and extraction program of: heating for 5 min, static extraction for 5 min, nitrogen purging for 100 s, and static circulation 2 or 3 times. S200. The concentrated extract was purified using an HLB solid-phase extraction column, with a 1:1 methanol-acetonitrile mixed solvent as the eluent. The eluent was collected and concentrated, and after adding an internal standard, it was filtered to obtain the sample to be tested. S300. The concentration of neonicotinoid compounds in standard solutions and test samples was analyzed using high performance liquid chromatography-tandem triple quadrupole mass spectrometry. The chromatographic conditions included: column: C18 column; mobile phase A: ultrapure water containing 0.1%, v / v formic acid + 2 mmol / L to 5 mmol / L ammonium acetate; mobile phase B: methanol; flow rate: 0.3 mL / min; column temperature: 40℃; gradient elution program: 0 min, 10% mobile phase B; 0 min to 5 min, 10% mobile phase B to 45% mobile phase B; 5 min to 9 min, 45% mobile phase B to 80% mobile phase B; 9 min to 9.1 min, 80% mobile phase B to 10% mobile phase B; 9.1 min to 10.1 min, 10% mobile phase B. Mass spectrometry conditions included: electrospray ionization source, positive ion mode; ion source spray voltage: 3500 V; ion source temperature: 300 °C; nebulizer gas: 30 psi; dryer gas temperature: 325 °C; sheath gas temperature: 350 °C; dryer gas flow rate: 6 L / min; sheath gas flow rate: 11 L / min. S400. Perform linear regression on the ratio of the mass spectrometric peak area of ​​the analyte to the internal standard in the standard solution and the mass concentration of the analyte to obtain the linear equation; S500. Substitute the mass spectrum peak area ratio of the analyte to the internal standard in the sample into the linear equation obtained in step S400 to calculate the concentration of neonicotinoids in the sample.

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