Method for enriching risky substances in large-volume water sample

Abstract

The invention belongs to the field of analysis of risky substances, and relates to a method for enriching risky substances in a large-volume water sample. According to the enrichment method, a micro-extraction device is adopted to enrich risky substances in a water sample to be detected, and the micro-extraction device comprises a liquid conveying device and an injector column tube; the injector column tube is filled with a solid support material, and the solid support material is loaded with a deep eutectic solvent; based on 100 mg of the solid support material, the addition amount of the deep eutectic solvent is 150-250 [mu] L; comprising the following steps: (1) adding a water sample to be detected into a liquid conveying device, enabling the water sample to flow through an injector column tube under the action of gravity, and extracting through a deep eutectic solvent loaded on a solid support material; and (2) after the extraction is finished, eluting by using an elution solvent to obtain an eluent. The device disclosed by the invention can be used for directly treating a water sample of more than or equal to 100mL, the enrichment multiple of more than hundreds of times is realized, and the application range is obviously expanded.

Description

Technical Field

[0001] This invention belongs to the field of hazardous substance analysis, specifically, it relates to a method for enriching hazardous substances in large-volume water samples. Background Technology

[0002] Hazardous substances (also known as dangerous substances) are chemical substances or mixtures that, due to their physicochemical properties, toxicity, or environmental hazards, may pose a direct or potential threat to human health, the ecological environment, or property safety. Psychoactive substances are chemical substances that can alter brain function and temporarily affect perception, mood, consciousness, cognition, or behavior by acting on the central nervous system (CNS). Their mechanisms of action typically involve interactions with neuronal receptors, neurotransmitter systems, or ion channels. However, improper disposal of unused drugs and drug abuse can lead to these compounds entering the environment through wastewater discharge, becoming emerging environmental pollutants. Therefore, establishing highly sensitive and accurate analytical methods to assess the residual levels of hazardous substances in environmental water samples is crucial for environmental monitoring and drug abuse surveillance.

[0003] Chromatographic techniques, especially high-performance liquid chromatography (HPLC), have significantly improved the instrumental detection capabilities of hazardous substances. However, due to the extremely low concentrations of these compounds in the environmental matrix, efficient sample pretreatment (particularly enrichment steps) remains crucial for enhancing analytical sensitivity. Although traditional techniques such as liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are widely used, they still suffer from significant drawbacks when processing large volumes of water samples, including high consumption of organic solvents, cumbersome operations, and time-consuming processes.

[0004] To overcome the aforementioned problems, several novel microextraction techniques for the analysis of hazardous substances have emerged in recent years, including magnetic solid-phase extraction (MSPE), dispersive liquid-liquid microextraction (DLLME), and liquid-liquid microextraction. However, these methods are still limited by complex operating procedures or cumbersome adsorbent preparation steps. For example, solid-phase microextraction (SPME) requires a significant amount of time to prepare the adsorbent coating, while DLLME typically involves multi-step phase separation operations, such as salting out, ion pair formation, curing, or centrifugation. Furthermore, the extensive use of organic solvents in these methods poses environmental and health risks. Therefore, there is an urgent need to develop an environmentally friendly, efficient, and easy-to-operate microextraction strategy for the trace analysis of hazardous substance residues.

[0005] Hydrophobic deep eutectic solvents (DES) are increasingly becoming green extractants for DLLME in analytical chemistry due to their advantages such as low toxicity, low cost, and ease of preparation. However, DLLME processes usually still require additional steps such as vortexing, sonication, or phase separation, making them relatively complex and labor-intensive. In addition, early models of KF-SLME (including In-syringe KF-SLME and Pipette-tip KF-SLME) were mainly designed for small-volume samples (<5 mL), requiring repeated sample aspiration and multiple flow-through extractions. Due to limitations in device structure and operation, they could not effectively handle large-volume water samples. Summary of the Invention

[0006] To achieve high-level enrichment of hazardous substances in large-volume water samples, this invention develops a method for enriching hazardous substances in large-volume water samples. This method employs a microextraction device to enrich the hazardous substances in the water sample, loading a hydrophobic deep eutectic solvent (DES) onto a solid support material to construct a syringe column device connected to a large-volume liquid delivery system. This method features gravity-driven flow, simplified operation, and requires no electricity or auxiliary equipment. To further enhance the environmental sustainability of this method, the development process particularly emphasizes the use of green solvents and materials, aiming to provide a robust, eco-friendly, and field-deployable solution for environmental trace monitoring and analysis.

[0007] To achieve the above objectives, the present invention provides a method for enriching hazardous substances in large-volume water samples. The enrichment method uses a microextraction device to enrich the hazardous substances in the water sample to be tested. The microextraction device includes a liquid delivery device and a syringe column.

[0008] The liquid conveying device is used to contain and convey the water sample to be tested, and the liquid conveying device is equipped with a liquid phase outlet pipeline;

[0009] The liquid phase outlet pipeline of the liquid delivery device is tightly connected to the large end of the syringe column tube.

[0010] The syringe column is filled with a solid support material, and the solid support material is loaded with a deep eutectic solvent; based on 100 mL of water sample to be tested, the amount of solid support material is 40-60 mg; based on 100 mg of solid support material, the amount of deep eutectic solvent added is 150-250 μL.

[0011] The enrichment method includes the following steps:

[0012] (1) The water sample to be tested is added to the liquid delivery device and flows through the syringe column under the action of gravity to be extracted by the deep eutectic solvent loaded on the solid support material;

[0013] (2) After extraction, use elution solvent to elute and obtain eluent.

[0014] The present invention has the following advantages:

[0015] (1) Significant differences in sample flow path: The present invention adopts a one-time through-flow path design, and the sample passes through the extraction unit continuously in one direction under the action of gravity, avoiding the efficiency reduction and repeated operation errors caused by multiple suction.

[0016] (2) Different driving forces: Existing technologies rely on manual pushing and pulling or repeated pressure to drive the sample flow, while the present invention uses gravity flow to achieve sample passage, eliminating repeated mechanical operations, making it easy to operate and suitable for on-site deployment.

[0017] (3) Significantly improved processing capacity: Traditional in-syringe or Pipette-tip KF-SLME are limited by their structural volume and can only process samples <5mL, resulting in limited enrichment folds and unsuitability for high-enrichment requirements. The device of this invention can directly process water samples ≥100mL, achieving enrichment folds of over 100 times, significantly expanding its applicability.

[0018] (4) Simplified operation: This invention eliminates the need for repeated aspiration of sample solution for extraction, avoiding the problems of high labor intensity and poor repeatability. The overall process is simplified to three steps: "extraction phase loading - gravity flow extraction - elution".

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0020] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings.

[0021] Figure 1 A schematic diagram of the DES-KF-SLME method of the present invention for processing large volume water samples is shown.

[0022] Figure 2 A visual representation of the DES-KF-SLME extraction process of the present invention is shown: (A) Stepwise extraction process: (a) valve opening, (b) initial stage, (c) intermediate stage, (d) final stage of extraction process; (B) color changes observed before extraction, after extraction and after desorption, illustrating the enrichment and transfer of analytes.

[0023] Figure 3The present invention provides an optimization of DES-KF-SLME extraction conditions based on single-factor experiments: (A) DES type, (B) HBA:HBD molar ratio of DES, (C) DES dosage, (D) H3PO4 dosage, (E) extraction time, (F) type of desorption solvent, and (G) volume.

[0024] Figure 4 The reproducibility study of the DES-KF-SLME method of the present invention is shown: (A) images of different batches of kapok fibers, (B) comparison of the extraction effect of NSAIDs using different batches of kapok fibers.

[0025] Figure 5 The following are HPLC-UV chromatograms of NSAIDs of the present invention: (a) NSAID standard solution (100 ng / mL) treated by the DES-KF-SLME method; (b) NSAID standard solution (100 ng / mL) treated by the KF-SLME step without DES; (c) Untreated NSAID standard solution (10 μg / mL); (d) Blank solution treated by the DES-KF-SLME method.

[0026] Figure 6 The following are LC-MS chromatograms of 3-hydroxyphenylcyclohexylpiperidine: (A) untreated 3-hydroxyphenylcyclohexylpiperidine standard solution (1 ng / mL); (B) 3-hydroxyphenylcyclohexylpiperidine standard solution treated with DES via the KF-SLME step (0.01 ng / mL).

[0027] Figure 7 The following LC-MS chromatograms of naposine are shown: (A) untreated naposine standard solution (1 ng / mL); (B) naposine standard solution treated with DES via the KF-SLME step (0.01 ng / mL).

[0028] Figure 8 The following LC-MS chromatograms of buprenorphine are shown: (A) untreated buprenorphine standard solution (1 ng / mL); (B) buprenorphine standard solution treated with DES via the KF-SLME step (0.01 ng / mL).

[0029] Figure 9 The following are LC-MS chromatograms of methadone: (A) untreated methadone standard solution (1 ng / mL); (B) methadone standard solution treated with DES via the KF-SLME step (0.01 ng / mL).

[0030] Figure 10The following LC-MS chromatograms of diphenoxylate are shown: (A) untreated diphenoxylate standard solution (1 ng / mL); (B) diphenoxylate standard solution treated with DES via the KF-SLME step (0.01 ng / mL). Detailed Implementation

[0031] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0032] This invention provides a method for enriching hazardous substances in large-volume water samples. The enrichment method uses a microextraction device to enrich the hazardous substances in the water sample to be tested. The microextraction device includes a liquid delivery device and a syringe column.

[0033] The liquid conveying device is used to contain and convey the water sample to be tested, and the liquid conveying device is equipped with a liquid phase outlet pipeline;

[0034] The liquid phase outlet pipeline of the liquid delivery device is tightly connected to the large end of the syringe column tube.

[0035] The syringe column is filled with a solid support material, and the solid support material is loaded with a deep eutectic solvent; based on 100 mL of water sample to be tested, the amount of solid support material is 40-60 mg; based on 100 mg of solid support material, the amount of deep eutectic solvent added is 150-250 μL.

[0036] The enrichment method includes the following steps:

[0037] (1) The water sample to be tested is added to the liquid delivery device and flows through the syringe column under the action of gravity to be extracted by the deep eutectic solvent loaded on the solid support material;

[0038] (2) After extraction, use elution solvent to elute and obtain eluent.

[0039] According to the present invention, preferably, the volume of the water sample to be tested is ≥100mL.

[0040] This invention uses hydrophobic and porous kapok fiber as a solid support material.

[0041] According to the present invention, preferably, the deep eutectic solvent is a mixture of hydrogen bond acceptors and hydrogen bond donors;

[0042] The hydrogen bond acceptor is methyltrioctylammonium bromide;

[0043] The hydrogen bond donor is selected from at least one of n-butanol, hexanol, octanol, and decanol;

[0044] The molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:1-5.

[0045] According to the present invention, preferably, the deep eutectic solvent is obtained by mixing hydrogen bond acceptors and hydrogen bond donors under stirring conditions, and the mixing temperature is 40-60°C.

[0046] According to the present invention, preferably, the deep eutectic solvent is a mixture of methyltrioctylammonium bromide and decanol, wherein the molar ratio of methyltrioctylammonium bromide and decanol is 1:2-4.

[0047] During extraction, especially under conditions of large-volume aqueous solution flow, the ability of DES to firmly adhere to the kapok fibers is a key factor for the success of this method. Therefore, the adhesion of the extractant to the support medium was initially evaluated. Several DES compositions were tested, with the DES composed of methyltrioctylammonium bromide (MTOAB) and decanol exhibiting the highest viscosity and adhering firmly to the kapok fiber support. In contrast, the other three DES (using thymol / eucalyptol as HBD and menthol as HBA) partially leached from the fiber support into the aqueous phase. Therefore, the MTOAB-decanol combination was selected as the optimal extractant for the proposed DES-KF-SLME method.

[0048] According to the present invention, preferably, the liquid conveying device is a separating funnel.

[0049] According to the present invention, preferably, the hazardous substance is a psychoactive substance and / or a nonsteroidal anti-inflammatory drug (NSAID); the psychoactive substance is selected from at least one of noscapine, buprenorphine, diphenoxylate, and 3-hydroxyphenylcyclohexadiazine (3-OH-PCP); the nonsteroidal anti-inflammatory drug is selected from at least one of ketoprofen, flurbiprofen, ibuprofen, and mefenamic acid.

[0050] According to the present invention, preferably, step (1) further includes applying positive or negative pressure to increase the flow rate.

[0051] In this invention, for simplicity and ease of operation, an extraction time of 35-45 minutes is selected as the optimal condition for subsequent experiments. This condition allows the solution to flow under gravity without the need for external pressure. However, if a shorter processing time is required, positive pressure from the top or negative pressure from the bottom can be applied to accelerate the extraction.

[0052] According to the present invention, preferably, the elution solvent is selected from at least one of ethanol, methanol, acetonitrile and acetone; the volume ratio of the deep eutectic solvent to the elution solvent is 1:2-12 (deep eutectic solvent).

[0053] Unless otherwise stated, all reagents used in this invention are of analytical grade and are commercially available.

[0054] Unless otherwise specified, all reagents used in this study were of analytical grade. NSAID standards, including ketoprofen (KTP, ≥98%), flurbiprofen (FBF, ≥98%), ibuprofen (IBP, ≥98%), and mefenamic acid (MFA, ≥99%), were purchased from Sigma-Aldrich Co., Ltd. (St. Louis, Missouri, USA). Noscapine, buprenorphine, diphenoxylate, and 3-OH-PCP (98% purity) were purchased from Shanghai Yuansi Standard Technology Co., Ltd. n-Butanol, hexanol, octanol, and decanol (97-99% purity) were purchased from Shanghai Anaiji Co., Ltd. Ethanol (EtOH), methyltrioctylammonium bromide (MTOAB, ≥98%), phosphoric acid (H3PO4, ≥85.0%), HPLC-grade methanol, acetone, and acetonitrile (ACN) were purchased from Shanghai Adamas Reagent Technology Co., Ltd.

[0055] Kapok fiber was purchased from the local market in Zhengzhou (Henan, China) and can be used directly without further pretreatment. A 5mL syringe was purchased from Zhengzhou Shuguang Medical Equipment Co., Ltd. A 250mL spherical dispensing funnel was purchased from Taobao (Jiangsu, China).

[0056] DES was prepared using a temperature-controlled magnetic stirrer (Zhengzhou Yuxiang Instrument Equipment Co., Ltd., China). Quantitative analysis of the target hazardous substances (NSAIDs) was performed using a Shimadzu LC-20AT high-performance liquid chromatography system equipped with an autosampler, binary pump, and UV-Vis detector. Chromatographic separation was performed using an Agilent Zorbax SB-C... 18 The column (150×4.6mm, 5μm) used ACN and 20mM phosphate buffer as the mobile phase.

[0057] (PBS, pH 4.0), eluted isocratically at a ratio of 38:62 (v / v) at a flow rate of 1.00 mL / min. Detection wavelength was 230 nm, and injection volume was 20 μL.

[0058] Quantitative analysis of the target risk substance (psychoactive substance) was performed using an Agilent 1290 Infinity II ultra-high performance liquid chromatograph coupled with a 6495D triple quadrupole mass spectrometer (HPLC-MS / MS) system. Gradient elution was performed using 0.1% formic acid aqueous solution (phase A) and acetonitrile (phase B) as the mobile phase. The gradient program was set as follows: 95% phase A was maintained for 0-2 min; the proportion of phase A decreased linearly from 95% to 70% within 2-6 min; and then decreased to 5% within 6-6.5 min, maintaining 5% phase A until 20 min. A Shim-pack GIST-HP C18-AQ column (2.1×100 mm, 1.9 μm) was used, with a column temperature of 35℃, a flow rate of 0.3 mL / min, and an injection volume of 1 μL. Mass spectrometry was performed in positive ion mode (ESI+) with multiple reaction monitoring (MRM). The parameters were set as follows: nebulizer gas pressure 35.0 psi, dry gas and sheath gas flow rates 13.0 L / min and 11.0 L / min, respectively; dry gas temperature maintained at 200 °C, and sheath gas temperature set at 350 °C. Data were acquired and analyzed using an Agilent MassHunter workstation.

[0059] Extraction recovery rate (ER%) refers to the efficiency of extracting a target analyte from a water sample into an extraction material, and is defined as:

[0060] ER% = n E / n0×100

[0061] variable n E n0 and n0 represent the amounts of analyte in the eluent and the original water sample, respectively.

[0062] Example 1

[0063] Preparation of DES: Hydrophobic DES was prepared by stirring-heating according to the method described in the literature (Fattahi et al., 2022). In short, MTOAB (as hydrogen bond acceptor, HBA) and a long-chain organic alcohol (as hydrogen bond donor, HBD) were placed in a sealed round-bottom flask at a specific molar ratio and magnetically stirred in a 50°C water bath until a homogeneous, transparent liquid was formed. The resulting DES was cooled and transferred to a dry glass vial for storage at room temperature.

[0064] The device was constructed in two steps: (1) 100 mg of kapok fiber was filled into a 5 mL syringe barrel, and then 200 μL of pre-prepared hydrophobic DES was added to load it onto the kapok fiber; (2) the syringe barrel was tightly connected to a 250 mL spherical separatory funnel through a perforated rubber stopper.

[0065] DES-KF-SLME Operation Method: The process is as follows Figure 1As shown, after the apparatus is assembled, 200 mL of the water sample to be tested is added to the separatory funnel. The sample flows through the DES-supported column under gravity for extraction, and the entire process takes approximately 40 minutes. To increase the flow rate, negative pressure can be applied to effectively shorten the process. Finally, ethanol is used to elute the DES adhering to the kapok fibers, and the eluent is directly transferred to an HPLC vial for subsequent detection.

[0066] To more intuitively demonstrate the enrichment effect of the developed method in processing large-volume water samples, a model water sample was used to validate the method, replacing the target analyte with Oil Red O dye. Figure 2 As shown in A(ad), the color of the SLME column (marked by the red dashed box) gradually deepens as the sample solution flows through it, indicating that the hydrophobic dye is effectively retained in the kapok fibers immobilized by DES, visually demonstrating the dynamic accumulation of the target analyte during gravity-driven extraction. Figure 2 B further demonstrated the validation results: the column was pale before extraction, while the model solution was distinctly red; after extraction, the column showed a significant red color, and the treated aqueous solution was almost colorless; a red concentrate was obtained after ethanol elution. This series of phenomena clearly demonstrates the efficient enrichment capability and visual traceability of the DES-KF-SLME method for hydrophobic compounds in large-volume water samples.

[0067] DES-KF-SLME condition optimization:

[0068] To obtain optimal extraction efficiency, this invention employs single-factor experiments to optimize key experimental parameters, including the type of DES, the HBA:HBD molar ratio, the amount of DES used, extraction time, and the type and volume of the elution solvent. The experiment used a 100 ng / mL spiked aqueous solution as the model, and involved three repeated extractions. The average extraction recovery rate of four NSAIDs (KTP, FBF, IBP, and MFA) was used as the evaluation index.

[0069] (1) Types of DES

[0070] The type of DES is a key factor determining its physicochemical properties, which in turn affects extraction efficiency. To optimize performance, a series of DES were synthesized using MTOAB as the HBA and four different organic alcohols (n-butanol, hexanol, octanol, and decanol) as the HBD. For example... Figure 3 As shown in Figure A, the extraction recovery gradually increases with increasing alkyl chain length of the alcohol, with the MTOAB-decanol system exhibiting the highest extraction efficiency. This trend indicates that hydrophobic interactions are the primary driving force behind the effective extraction of hazardous substances using the DES employed in this invention. Therefore, a DES composed of decanol and MTOAB was selected for subsequent experiments.

[0071] (2) HBA:HBD molar ratio of DES

[0072] The hydrophobicity of DES can be strategically altered by changing the molar ratio of HBA to HBD. Therefore, the HBA:HBD molar ratio was systematically investigated within the range of 1:1 to 1:5. Figure 3 As shown in Figure B, the highest extraction recovery rate of hazardous substances was achieved at a molar ratio of 1:3. Therefore, MTOAB-decyl alcohol DES was prepared subsequently at a molar ratio of 1:3.

[0073] (3) DES dosage

[0074] Optimizing the DES dosage is crucial for ensuring sufficient adsorption capacity and maximizing extraction recovery. To determine the optimal dosage, the synthesized DES volume was varied from 50 μL to 300 μL. Figure 3 As shown in Figure C, the extraction recovery of the hazardous substance peaked at a DES volume of 200 μL. Increasing the volume beyond 200 μL did not lead to further improvement, indicating that the recovery reached a plateau. Therefore, 200 μL of DES was selected as the optimal extraction solvent.

[0075] (4) H3PO4 dosage

[0076] As an acidic drug, when the sample pH is acidic, the risk substance exists primarily in its molecular form, resulting in a higher partition coefficient in the DES phase and thus improving the extraction recovery. This result may be attributed to the combined effect of hydrophobic partitioning and electrostatic interactions. On the one hand, at lower pH levels, the risk substance mainly remains in a neutral form, which is favorable for partitioning into the hydrophobic DES phase; on the other hand, the DES contains MTOAB, a quaternary ammonium salt compound that can form electrostatic interactions with the anionic form of the risk substance. This dual mechanism of neutral molecular partitioning and electrostatic interactions synergistically maintains high extraction efficiency, even when the amount of added acid is reduced or completely omitted. Figure 3 D). Considering ease of operation and environmental friendliness, phosphoric acid was not added in subsequent experiments.

[0077] In the examples, for alkaline drugs, the aqueous solution was adjusted to pH 11 before extraction. The hazardous substances mainly exist in their molecular form. During the desorption process, 3% FA in methanol was added.

[0078] (5) Extraction time

[0079] During extraction, the sample solution can flow through DES-supported kapok fibers under gravity or pressure assistance. Extraction can be accelerated by applying positive pressure from the top or negative pressure from the bottom. Since this variable can affect reproducibility and recovery, and is a key factor for achieving reliable quantitative analysis, its impact was first investigated. The average extraction time was used as the basis for evaluation. Figure 3E showed that reducing the extraction time from 40 minutes to 10 minutes resulted in only a slight decrease in recovery. For simplicity and ease of operation, an extraction time of 40 minutes was chosen as the optimal condition for subsequent experiments, allowing the solution to flow under gravity without the need for external pressure. However, if a shorter processing time is required, positive or negative pressure can be applied.

[0080] (6) Types and amounts of desorption solvent

[0081] Choosing the appropriate elution solvent and its volume is crucial for maximizing the recovery of the target analyte. Common elution solvents, including ethanol, methanol, acetonitrile, and acetone, were systematically evaluated. Figure 3 As shown in Figure F, all the solvents examined exhibited effective desorption capabilities for DES-loaded analytes. Among them, ethanol was selected as the optimal elution solvent due to its excellent performance, low cost, low toxicity, and environmental friendliness.

[0082] Subsequently, the enrichment factor was used as an evaluation criterion to optimize the eluent dosage, which directly affects the detection sensitivity. For example... Figure 3 As shown in G, the enrichment factor of the hazardous substance decreased significantly with increasing ethanol content. Therefore, to maintain high detection sensitivity, a minimum elution volume of 0.6 mL was selected for subsequent experiments.

[0083] Based on the single-factor optimization results, the optimal experimental conditions were determined as follows: MTOAB-decyl alcohol DES was prepared according to the HBA:HBD molar ratio of 1:3, using 200 μL of DES, without adjusting the pH of the sample solution, gravity-driven extraction for about 40 minutes, and 0.6 mL of ethanol as the elution solvent.

[0084] (7) Reproducibility study of different batches of kapok fiber

[0085] The robustness of the proposed DES-KF-SLME method was further evaluated by extracting spiked water samples using kapok fibers from different production batches as support materials. Four batches of kapok fibers from different suppliers (purchased through Taobao Marketplace) were examined, and the results are as follows: Figure 4 As shown, the extraction recovery rates were consistent across all batches, indicating good reproducibility. This may be because the kapok fiber serves only as a support medium, while the extraction efficiency is primarily determined by the partition coefficient of the hazardous substance between the DES and the water sample, as well as the electrostatic interaction between the hazardous substance and the MTOAB component in the DES.

[0086] The extraction performance of the DES-KF-SLME method was further validated using NSAID-spiked water samples (100 ng / mL) and a blank control. Figure 5As shown, the spiked sample treated with the DES-KF-SLME step (curve a) exhibited clear separation peaks for KTP, FBF, IBP, and MFA, with retention times highly matching those of the untreated 10 μg / mL standard solution (curve c), and peak intensities significantly increased, confirming the method's efficient enrichment capability. In contrast, the signal intensity of the same spiked sample treated with the KF-SLME step without DES (curve b) was significantly reduced, indicating that the extraction efficiency provided by kapok fiber alone is limited. Furthermore, no interfering peaks were observed in the blank water sample treated with DES-KF-SLME (curve d), indicating that the method has good selectivity and is suitable for analysis of complex matrices.

[0087] In summary, the experimental results fully support the feasibility of the proposed DES-KF-SLME method for selective and sensitive extraction of NSAIDs from large-volume environmental water samples.

[0088] The extraction performance of the DES-KF-SLME method was verified using water samples spiked with psychoactive substances (3-OH-PCP, noscapine, buprenorphine, methadone, and diphenoxylate, respectively) (0.01 ng / mL). Chromatographic analysis is as follows: Figure 6-10 As shown, by Figure 6-10 It can be seen that the spiked samples treated by the DES-KF-SLME step Figure 6-10 B exhibits clear separation peaks from 3-OH-PCP, noscapine, buprenorphine, methadone, and diphenoxylate standard solutions, with retention times comparable to those of the untreated 1 ng / mL standard solution. Figure 6-10 The A) showed a high degree of matching, and the peak intensity was significantly improved, confirming that the method has efficient enrichment capabilities.

[0089] In summary, the experimental results fully support the feasibility of the proposed DES-KF-SLME method for the selective and sensitive extraction of psychoactive substances from large-volume environmental water samples.

[0090] The recoveries of psychoactive substances spiked in aqueous samples (the spiked samples were noscapine and buprenorphine) were studied. The experiment used 0.01 ng / mL spiked aqueous solutions as the model, and three repeated extractions were performed. The average extraction recovery rate of the two psychoactive substances was used as the evaluation index. The extraction recovery results are shown in Table 1.

[0091] Table 1

[0092] Na Ke Ting Buprenorphine Recovery rate 97.60％ 81.20％

[0093] As shown in Table 1, this method uses DES-loaded kapok fibers and leverages a synergistic mass transfer mechanism, requiring only 200 μL of extractant to process 200 mL of water sample. High recovery rates of psychoactive substances (>81.20%) can be achieved without nitrogen blowing or concentration steps. This performance is particularly advantageous for large-volume, low-concentration environmental monitoring applications.

[0094] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for enriching hazardous substances in large-volume water samples, characterized in that, The enrichment method uses a microextraction device to enrich hazardous substances in the water sample to be tested. The microextraction device includes a liquid delivery device and a syringe column. The liquid conveying device is used to contain and convey the water sample to be tested, and the liquid conveying device is equipped with a liquid phase outlet pipeline; The liquid phase outlet pipeline of the liquid delivery device is tightly connected to the large end of the syringe column tube. The syringe column is filled with a solid support material, and the solid support material is loaded with a deep eutectic solvent; based on 100 mL of water sample to be tested, the amount of solid support material is 40-60 mg; based on 100 mg of solid support material, the amount of deep eutectic solvent added is 150-250 μL. The enrichment method includes the following steps: (1) The water sample to be tested is added to the liquid delivery device and flows through the syringe column under the action of gravity to be extracted by the deep eutectic solvent loaded on the solid support material; (2) After extraction, use elution solvent to elute and obtain eluent.

2. The method for enriching hazardous substances in environmental water according to claim 1, wherein, The volume of the water sample to be tested is ≥100mL.

3. The method for enriching hazardous substances in large-volume water samples according to claim 1, wherein, The solid support material is kapok fiber.

4. The method for enriching hazardous substances in large-volume water samples according to claim 1, wherein, The deep eutectic solvent is a mixture of hydrogen bond acceptors and hydrogen bond donors; The hydrogen bond acceptor is methyltrioctylammonium bromide; The hydrogen bond donor is selected from at least one of n-butanol, hexanol, octanol, and decanol; The molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:1-5.

5. The method for enriching hazardous substances in large-volume water samples according to claim 4, wherein, The deep eutectic solvent is obtained by mixing hydrogen bond acceptors and hydrogen bond donors under stirring conditions at a mixing temperature of 40-60℃.

6. The method for enriching hazardous substances in large-volume water samples according to any one of claims 1-5, wherein, The deep eutectic solvent is a mixture of methyltrioctylammonium bromide and decanol, wherein the molar ratio of methyltrioctylammonium bromide to decanol is 1:2-4.

7. The method for enriching hazardous substances in large-volume water samples according to claim 1, wherein, The liquid delivery device is a separating funnel.

8. The method for enriching hazardous substances in large-volume water samples according to claim 1, wherein, The hazardous substance is a psychoactive substance and / or a nonsteroidal anti-inflammatory drug; the psychoactive substance is selected from at least one of noscapine, buprenorphine, diphenoxylate and 3-hydroxyphenylcyclohexadiazine; the nonsteroidal anti-inflammatory drug is selected from at least one of ketoprofen, flurbiprofen, ibuprofen and mefenamic acid.

9. The method for enriching hazardous substances in large-volume water samples according to claim 1, wherein, Step (1) also includes increasing the flow rate by applying positive or negative pressure.

10. The method for enriching hazardous substances in large-volume water samples according to claim 1, wherein, The elution solvent is selected from at least one of ethanol, methanol, acetonitrile, and acetone; The volume ratio of the deep eutectic solvent to the elution solvent is 1:2-12.

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