A dgt device for polycyclic aromatic hydrocarbon monitoring and its application

Abstract

The application discloses a DGT device for monitoring polycyclic aromatic hydrocarbons and application thereof, and belongs to the field of environmental chemistry. The device comprises a filter membrane, a diffusion membrane, an adsorption membrane and a shell for fixing the filter membrane, the diffusion membrane and the adsorption membrane, wherein the shell is made of metal, the filter membrane is a Nuclepore track etching membrane, and the adsorption membrane is an agarose membrane containing MIP particle. The device is used for monitoring polycyclic aromatic hydrocarbons, and the MIP particle-containing adsorption membrane is used as a binding phase, has a high adsorption capacity for polycyclic aromatic hydrocarbons in a water environment, guarantees the integrity of sampling, and reduces the adsorption of polycyclic aromatic hydrocarbons by using a metal shell and a Nuclepore track etching filter membrane, is not affected by ion strength, pH value and soluble organic matter in the environment, further guarantees the accuracy of results, and realizes accurate in-situ monitoring of polycyclic aromatic hydrocarbons in the water environment.

Description

Technical Field

[0001] This application belongs to the field of environmental chemistry, specifically relating to a DGT device for monitoring polycyclic aromatic hydrocarbons and its application. Background Technology

[0002] Polycyclic aromatic hydrocarbons (PAHs) are typical persistent organic pollutants, characterized by long persistence in the environment, high toxicity, and extreme difficulty in degradation. Although present in minute quantities in the environment, PAHs are widely distributed in air, water, soil, and sediments. During their continuous migration and transformation, they can enter organisms through the respiratory tract and skin, posing significant threats to human health and the natural environment. PAHs have been reported to exhibit genotoxicity, reproductive and endocrine disruption effects, immunotoxicity, and neurotoxicity (SUN. et al., Sci Total Environ, 773, 145403; Sushkova, S. et al., Sci Total Environ, 655 (MAR. 10), 232-241). Therefore, reliable and stable sampling and measurement techniques are crucial not only for understanding the environmental behavior of PAHs but also for assessing their environmental risks.

[0003] To date, monitoring of polycyclic aromatic hydrocarbons (PAHs) in aquatic environments has mostly been accomplished through active sampling. However, because PAH concentrations are low in natural water bodies, large quantities of water samples are required. This process is time-consuming and labor-intensive, and the transportation, storage, and pretreatment of samples can affect the properties of PAHs, thus impacting the accuracy of the measurement results. Furthermore, active sampling only measures the instantaneous concentration at the time of sampling, affecting the representativeness of the results; therefore, multiple samplings are often necessary.

[0004] Passive sampling, as an in-situ sampling technique, eliminates the need for collecting large amounts of water samples, thus avoiding the influence of sample transportation and storage on the concentration of the analyte. Furthermore, passive samplers can be placed in the environment for short or long periods to enrich and capture trace substances, ultimately reflecting the time-weighted average (TWA) concentration of the analyte during the sampler's placement, making the monitoring results representative. Diffusive gradients in thin films (DGT), invented by David Williams and Hao Zhang of Lancaster University in the UK, is an in-situ, non-destructive passive sampling technique. Its principle is that the analyte, after passing through a diffusion membrane (diffusive gel), is irreversibly adsorbed by an adsorption membrane (resingel). Because the flux (or diffusion coefficient) is only related to the environmental concentration and temperature of the analyte, the environmental concentration of the analyte can be obtained by analyzing the amount adsorbed on the adsorption membrane using Fick's first law. Currently, DGT technology has been widely used in the determination of heavy metals in water, soil and sediments, and its application in the determination of organic matter is also gradually emerging (Wang., et al., Anal. Chem., 2019, 91(20).).

[0005] However, existing DGT devices are affected by the properties of organic matter and environmental factors when monitoring polycyclic aromatic hydrocarbons (PAHs). Therefore, there is an urgent need to develop a novel DGT device and monitoring method for PAHs. Summary of the Invention

[0006] 1. The problem to be solved

[0007] This application addresses several shortcomings of existing technologies for monitoring PAHs using active sampling methods. These include cumbersome processing procedures that can lead to analyte loss and reduced accuracy; the need to collect large quantities of samples for trace amounts of PAHs, increasing transportation and time costs; and the problem of material loss due to the large amount of analyte adsorbed by the plastic casing of DGT devices, further reducing detection accuracy. This application provides a metal-cased DGT device, which minimizes analyte loss. Furthermore, this application offers a method for monitoring PAHs based on a metal-cased DGT device. This method utilizes in-situ DGT technology to monitor PAHs. The device includes an adsorption membrane prepared from molecularly imprinted compounds (MIPs). After sampling, the membrane is eluted to obtain an eluent, and the concentration of polycyclic aromatic hydrocarbons (PAHs) in the eluent is then measured. This method enables accurate monitoring of PAHs without requiring large sample collections, significantly reducing monitoring costs.

[0008] 2. Technical Solution

[0009] To solve the above problems, the technical solution adopted in this application is as follows:

[0010] This application provides a DGT device for monitoring polycyclic aromatic hydrocarbons (PAHs). The device includes a filter membrane, a diffusion membrane, an adsorption membrane, and a housing that fixes the filter membrane, diffusion membrane, and adsorption membrane. The housing is made of metal, and the metal housing can reduce ABS adsorption.

[0011] Furthermore, the aforementioned metal materials include aluminum, aluminum alloys, stainless steel, brass, or copper.

[0012] Furthermore, the aforementioned metal materials include aluminum, aluminum alloys, or stainless steel.

[0013] Furthermore, the aforementioned metal materials include aluminum or aluminum alloys.

[0014] Furthermore, the above-mentioned filter membrane is a cellulose acetate microporous filter membrane (CA), a mixed cellulose filter membrane (MCE), a nylon filter membrane, a Nuclepore track etching membrane (PC), a polyethersulfone membrane (PES), a polypropylene filter membrane (PP), a polytetrafluoroethylene membrane (PTFE), or a polyvinylidene fluoride filter membrane (PVDF).

[0015] Furthermore, the above-mentioned filter membrane is a Nuclepore track-etched membrane, which has a pore size of 0.4 μm and a thickness of 0.01 mm.

[0016] Furthermore, the aforementioned diffusion membrane is an agarose diffusion membrane.

[0017] Furthermore, the above-mentioned adsorption membrane is an agarose membrane containing molecularly imprinted compound (MIP) particles, with the MIP particles uniformly distributed in the agarose membrane matrix.

[0018] This application also provides an adsorption membrane for a DGT device, the adsorption membrane containing molecularly imprinted compound (MIP) particles uniformly distributed in an agarose membrane matrix.

[0019] This application also provides a method for preparing the above-mentioned adsorption membrane for a DGT device, the method comprising the following steps:

[0020] S1: Agarose powder, activated MIP particles and pure water are mixed and heated to boiling to make it transparent, thus obtaining an agarose solution containing MIP.

[0021] S2: Cool the above agarose solution containing MIP or add it to a mold for cooling to prepare an adsorption membrane containing molecularly imprinted compound (MIP) particles.

[0022] Furthermore, the particle size of the aforementioned MIP particles is 50–100 μm.

[0023] Furthermore, the activated MIP particles mentioned above are MIP particles activated with methanol. Methanol activation includes the following steps:

[0024] S11: Add MIP particles to methanol solvent, soak, centrifuge, remove supernatant to obtain precipitated solid; the volume-to-mass ratio of methanol solvent to MIP is (3~3.5):2 (mL / g);

[0025] S12: Ultrapure water washing, adding ultrapure water to the deposited solid and shaking treatment, centrifugation, removing the supernatant, repeating the above operation to obtain activated MIP particles.

[0026] Furthermore, in S1 above, the mass ratio of agarose powder, activated MIP particles and ultrapure water is 1:(10-10.5):50.

[0027] Furthermore, in S1 above, the contact mixing may also include ultrasonic treatment. During ultrasonication, the temperature of the ultrasonicated solution should be controlled not to exceed 10°C, as excessively high temperatures can easily affect the gelation of agarose.

[0028] Furthermore, the ultrasonic conditions for the above ultrasonic treatment are: ultrasonication in an ice bath for 5–10 minutes; ultrasonic frequency not lower than 80 kHz. Even further, the ultrasonic frequency is 99 kHz.

[0029] Furthermore, the above-mentioned method for preparing an adsorption membrane for a DGT device includes the following steps: weighing 0.2g of agarose and 10mL of Milli-Q water into an Erlenmeyer flask, adding 2g (wet weight) of activated MIP particles, and sonicating the Erlenmeyer flask in an ice bath for 5-10 minutes to mix all materials evenly; placing the Erlenmeyer flask on an electric furnace for heating, and when the aqueous solution becomes clear and is about to boil, gently shaking the Erlenmeyer flask and continuing to heat until boiling, at which point the solution is quickly and evenly transferred to a preheated glass plate to remove air bubbles; after standing at room temperature for 35 minutes, it can be cut into circular pieces with a diameter of 2.51cm using a mold.

[0030] This application also provides the above-mentioned adsorption membrane for DGT device and the application of DGT device for polycyclic aromatic hydrocarbon monitoring in polycyclic aromatic hydrocarbon monitoring.

[0031] This application also provides a method for monitoring polycyclic aromatic hydrocarbons (PAHs) based on DGT technology. The method uses the aforementioned DGT device for PAH monitoring to adsorb and monitor PAHs. After monitoring, the adsorption membrane is eluted with an eluent to obtain an eluent, and then the concentration of PAHs in the eluent is measured.

[0032] Furthermore, the above elution conditions are as follows: using acetonitrile as the eluent, sonicating for 30±2 min. The method is convenient, with high and stable elution efficiency. Under these elution conditions, the elution efficiency of polycyclic aromatic hydrocarbons on the MIP adsorption membrane reached over 90%.

[0033] Furthermore, the acetonitrile mentioned above is chromatographic grade acetonitrile.

[0034] Furthermore, the aforementioned polycyclic aromatic hydrocarbons include one or more of naphthalene, acenaphthene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene.

[0035] Furthermore, the aforementioned method for monitoring polycyclic aromatic hydrocarbons based on DGT technology specifically includes the following steps:

[0036] (1) Place the DGT device into the water body to be tested for monitoring of polycyclic aromatic hydrocarbons;

[0037] (2) Recovery and elution of adsorption membrane: After removing the DGT device from the water body to be tested, rinse the device with pure water, remove the adsorption membrane and place it in a brown glass bottle, add eluent to obtain the eluent;

[0038] (3) Determination of polycyclic aromatic hydrocarbons: The concentration of polycyclic aromatic hydrocarbons in the eluent obtained in step (2) was determined by high performance liquid chromatography-ultraviolet / fluorescence detection.

[0039] (4) Calculation of the adsorption amount of polycyclic aromatic hydrocarbons on the adsorption membrane: The adsorption amount of polycyclic aromatic hydrocarbons on the MIP adsorption membrane is calculated according to the following formula (1).

[0040]

[0041] Where M refers to the mass of polycyclic aromatic hydrocarbons adsorbed on the adsorption membrane, in ng; Ce refers to the concentration of polycyclic aromatic hydrocarbons in the eluent, in ng / mL; Vg refers to the volume of the adsorption membrane, in mL; Ve refers to the volume of the eluent, in mL; and Fe refers to the elution efficiency of polycyclic aromatic hydrocarbons on the adsorption membrane.

[0042] (5) Calculation of DGT concentration: According to Fick's first law of diffusion, the amount of analyte adsorbed on the adsorption membrane obtained in step (4) is converted into the concentration of DGT by formula (2).

[0043]

[0044] Among them, C DGT Δg is the concentration of polycyclic aromatic hydrocarbons (PAHs) measured by the DGT device, in ng / mL; Δg is the thickness of the diffusion layer (including the filter membrane and the diffusion membrane), in cm; D is the diffusion coefficient of PAHs in the diffusion membrane, in cm. 2 / s; A is the window area of ​​the DGT device, in cm².2 t is the placement time of the DGT device, in seconds.

[0045] 3. Beneficial effects

[0046] Compared with the prior art, the advantages of this application are as follows:

[0047] (1) This application provides a DGT device for monitoring polycyclic aromatic hydrocarbons. The device includes a filter membrane, a diffusion membrane, an adsorption membrane, and a shell for fixing the filter membrane, diffusion membrane, and adsorption membrane. The shell is made of metal. Compared with the traditional ABS shell, it reduces the adsorption of target polycyclic aromatic hydrocarbons and effectively improves the accuracy of DGT in monitoring polycyclic aromatic hydrocarbons in the environment.

[0048] (2) The DGT adsorption membrane provided in this application contains MIP particles that are uniformly distributed in the membrane substrate. Using it as the adsorption membrane in the DGT device, the DGT device assembled with the DGT adsorption membrane can accurately monitor a variety of polycyclic aromatic hydrocarbons. Compared with active sampling analysis, it does not require the collection of a large number of samples or a complicated sample extraction process, and reduces the use of organic solutions (active sampling requires tens of mL of organic reagents, while DGT only requires about 5 mL). This not only significantly reduces the monitoring cost, but also effectively avoids sample loss during the extraction process. The method is simple to operate.

[0049] (3) This application provides a method for monitoring polycyclic aromatic hydrocarbons (PAHs) based on DGT technology. This method utilizes a DGT device for PAH monitoring provided in this application for the adsorption and monitoring of PAHs. The device employs a metal-cased DGT assembly consisting of a MIP particle adsorption membrane, an agarose diffusion membrane, and a Nuclepore track-etched filter membrane. The MIP particle adsorption membrane serves as the binding phase, exhibiting high adsorption capacity for PAHs in the aquatic environment, ensuring the integrity of the sampling. Compared to HLB adsorption gels commonly used for organic matter monitoring, it is less susceptible to environmental factors. Simultaneously, the metal casing and Nuclepore track-etched filter membrane reduce PAH adsorption, further ensuring the accuracy of the results, thereby achieving accurate in-situ monitoring of PAHs in the aquatic environment.

[0050] (4) The method for monitoring polycyclic aromatic hydrocarbons (PAHs) based on DGT technology provided in this application is unaffected by the ionic strength, pH value, and soluble organic matter in the environment. The results of this application show that the ionic strength (calculated as NaCl) of the test aqueous solution is 0.01, 0.1, 0.25, and 0.5 mol / L, respectively, and the calculated PAH concentration C DGT The actual measured concentration of polycyclic aromatic hydrocarbons (PAHs) in the solution, C solnThe ratio remained stable; the pH values ​​of the aqueous solutions to be tested were 4, 6, and 8, and the calculated concentrations of polycyclic aromatic hydrocarbons (PAHs) C were... DGT The actual measured concentration of polycyclic aromatic hydrocarbons (PAHs) in the solution, C soln The ratio remained stable; the soluble organic matter in the test aqueous solutions were 0, 2, 5, 10, 15, and 20 mg / L, respectively, and the calculated polycyclic aromatic hydrocarbon concentration C was obtained. DGT The actual measured concentration of polycyclic aromatic hydrocarbons (PAHs) in the solution, C soln The ratio remained stable under conditions where the soluble organic matter was below 15 mg / L, indicating that ionic strength, pH value, and soluble organic matter had no significant impact on the determination by the method of the present invention, thus proving the stability and reliability of the method of the present invention.

[0051] (5) The method for monitoring polycyclic aromatic hydrocarbons based on DGT technology provided in this application uses acetonitrile as the eluent in the elution step after adsorption. It was found that more than 90% of polycyclic aromatic hydrocarbons can be eluted by sonication in 5 mL acetonitrile solution for 30 minutes. The elution efficiency is high and stable, and the operation is simple and feasible. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the DGT device structure;

[0053] Figure 2 The elution efficiency of the MIP adsorption membrane;

[0054] Figure 3 The change in the adsorption amount of polycyclic aromatic hydrocarbons over time;

[0055] Figure 4 The adsorption effect of various polycyclic aromatic hydrocarbons under different ionic strengths is shown in the figure.

[0056] Figure 5 The adsorption effect of various polycyclic aromatic hydrocarbons under different pH conditions is shown in the graph.

[0057] Figure 6 The adsorption effect of various polycyclic aromatic hydrocarbons under different soluble organic substances is shown in the figure.

[0058] Figure 7 Figures showing the adsorption effects of different metal materials on polycyclic aromatic hydrocarbons;

[0059] Figure 8 The diagram shows the adsorption effect of different shell materials on various polycyclic aromatic hydrocarbons.

[0060] Figure 9 The graph shows the adsorption effect of different filter membranes on various polycyclic aromatic hydrocarbons.

[0061] Figure 10 The adsorption performance of different adsorption membranes under different pH conditions is shown. Detailed Implementation

[0062] The present application will be further described below with reference to specific embodiments.

[0063] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0065] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0066] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0067] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0068] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0069] Example 1

[0070] This embodiment provides an adsorption membrane for a DGT device and its preparation method. The adsorption membrane is an agarose membrane containing molecularly imprinted compound (MIP) particles, with the MIP particles uniformly distributed in the agarose membrane matrix. The specific steps include the following:

[0071] (1) Activation of molecularly imprinted compound (MIP) materials

[0072] Methanol activation: Add 30 mL of methanol solvent to 20 g of MIP material, shake up and down to ensure that methanol and resin particles are in full contact, centrifuge at 3500 r / min for 10 min, remove the supernatant, and repeat the above steps 3 times to obtain the deposited solid.

[0073] Ultrapure water washing: Add ultrapure water twice the volume of the deposited solid to the obtained deposited solid, shake up and down to ensure that the ultrapure water fully contacts the activated particles, then centrifuge at 3500 r / min for 10 min, remove the supernatant, and repeat the above steps 3 times to obtain the deposited solid.

[0074] (2) Preparation of MIP adsorption membrane

[0075] Agar powder, activated MIP material and ultrapure water were mixed at a mass ratio of 1:10:50, and the mixture was ultrasonicated in an ice bath for 5 minutes at a frequency of 99 kHz.

[0076] Heat the ultrasonicated solution to boiling, and while it is still hot, pour it into two preheated (~70℃) glass plates sandwiched with 0.5mm U-shaped Teflon gaskets. After removing the air bubbles between the glass plates, place the glass plates horizontally at room temperature to cool for 35 minutes until the solution between the glass plates solidifies into a gel.

[0077] (3) Preservation of MIP adsorption membrane

[0078] After the above solution gels, the glass plate is pried open with a blade, and the gelled MIP adsorption membrane is cut into circular pieces with a diameter of 2.51 cm and stored in 0.01 mol / L NaCl at 4 °C.

[0079] Example 2

[0080] This embodiment provides a DGT device for monitoring polycyclic aromatic hydrocarbons, the device as follows: Figure 1 As shown, it includes a filter membrane, a diffusion membrane, an adsorption membrane, and a shell for fixing the filter membrane, diffusion membrane, and adsorption membrane, wherein:

[0081] The outer casing is made of metal, specifically aluminum in this embodiment;

[0082] The filter membrane can be a cellulose acetate microporous membrane (CA), a mixed cellulose membrane (MCE), a nylon membrane, a Nuclepore track-etched membrane (PC), a polyethersulfone membrane (PES), a polypropylene membrane (PP), a polytetrafluoroethylene membrane (PTFE), or a polyvinylidene fluoride membrane (PVDF); in this example, a Nuclepore track-etched membrane is used, with a pore size of 0.4 μm and a thickness of 0.01 mm.

[0083] The diffusion membrane is an agarose diffusion membrane;

[0084] The adsorption membrane is the adsorption membrane containing MIP particles prepared in Example 1.

[0085] Example 3

[0086] This embodiment provides the elution efficiency of the adsorption membrane containing MIP particles prepared in Example 1, and the specific steps;

[0087] (1) Place the adsorption membrane in an aqueous solution containing a certain concentration of polycyclic aromatic hydrocarbons for 24 hours and measure the change in the amount of polycyclic aromatic hydrocarbons in the aqueous solution before and after adsorption, M1.

[0088] (2) The adsorption membrane is placed in the eluent, which is 5 mL of pure acetonitrile solvent, and the elution condition is sonication for 30 minutes.

[0089] (3) Measure the amount of polycyclic aromatic hydrocarbons adsorbed by the adsorption membrane, M2;

[0090] (4) Calculate the elution efficiency of the adsorption membrane based on the change in the amount of adsorbed substance and the amount of substance in the aqueous solution:

[0091]

[0092] The results are as follows Figure 2 As shown, more than 90% of polycyclic aromatic hydrocarbons can be eluted by sonication in 5 mL of acetonitrile solution for 30 minutes. The elution efficiency is high and stable, and the operation is simple and feasible.

[0093] Example 4

[0094] This embodiment provides a method for monitoring polycyclic aromatic hydrocarbons (PAHs) based on DGT technology. The method utilizes the DGT device for PAH monitoring described in Example 2 for PAH adsorption and monitoring. After monitoring, the adsorption membrane is eluted with an eluent to obtain an eluent, and the concentration of PAHs in the eluent is then measured. The specific monitoring steps are as follows:

[0095] (1) Placement of DGT device: Place the assembled DGT device in an aqueous solution containing a certain concentration of polycyclic aromatic hydrocarbons, keep the aqueous solution in a fully stirred state during the DGT placement process, and record the temperature of the aqueous solution and the DGT placement time during the DGT device placement process.

[0096] (2) Recovery and elution of adsorption membrane: Take out the DGT device after placement, rinse the surface with ultrapure water, open the device, take out the adsorption membrane and place it in the elution solution. The elution solution is 5 mL of pure acetonitrile solvent, and the elution condition is sonication for 30 minutes.

[0097] (3) Determination of polycyclic aromatic hydrocarbons in the eluent: The concentration of polycyclic aromatic hydrocarbons in the eluent was determined by high performance liquid chromatography-ultraviolet / fluorescence detector;

[0098] (4) Calculation of the adsorption amount of polycyclic aromatic hydrocarbons on the MIP adsorption membrane: The adsorption amount of polycyclic aromatic hydrocarbons on the MIP adsorption membrane is calculated according to the following formula (1);

[0099]

[0100] Where M refers to the mass of polycyclic aromatic hydrocarbons adsorbed on the adsorption membrane, in ng; Ce refers to the concentration of polycyclic aromatic hydrocarbons in the eluent, in ng / mL; Vg refers to the volume of the adsorption membrane, in mL; Ve refers to the volume of the eluent, in mL; and Fe refers to the elution efficiency of polycyclic aromatic hydrocarbons on the adsorption membrane.

[0101] (5) Calculation of DGT concentration: According to Fick's first diffusion law, the amount of adsorption of the analyte on the adsorption membrane obtained in step (4) is converted into the concentration of DGT by formula (2).

[0102]

[0103] Among them, C DGT Δg is the concentration of polycyclic aromatic hydrocarbons (PAHs) measured by the DGT device, in ng / mL; Δg is the thickness of the diffusion layer (including the filter membrane and the diffusion membrane), in cm; D is the diffusion coefficient of PAHs in the diffusion membrane, in cm. 2 / s; A is the window area of ​​the DGT device, in cm². 2 t is the placement time of the DGT device, in seconds.

[0104] In this embodiment, the window area A is 3.14 cm². 2 The diffusion coefficients of various polycyclic aromatic hydrocarbons measured at a temperature of 25℃ are shown in Table 1.

[0105] Table 1. Diffusion coefficients of various polycyclic aromatic hydrocarbons

[0106] compound <![CDATA[D(10 -6 cm 2 s -1 )]]> Naphthalene (Nap) 6.95 Acyne 6.52 Ace 6.34 Flu 6.31 Phe 6.07 Anthracene (Ant) 6.06 Fluoranthene (Flua) 5.00 Pyr 5.21

[0107] The above eight polycyclic aromatic hydrocarbons were measured within a period of 0 to 7 days.

[0108] Figure 3 To demonstrate the change in the adsorption capacity of polycyclic aromatic hydrocarbons (PAHs) by the DGT device over time, the solid line in the figure represents the theoretical line calculated based on Fick's first diffusion law. The results show that the mass of PAHs enriched on the MIP adsorption membrane is in good agreement with the theoretical value, indicating that the DGT can accurately determine the concentration of PAHs in water even under long-term storage conditions.

[0109] Example 5

[0110] In this embodiment, the effects of different ionic strength conditions on the determination of polycyclic aromatic hydrocarbons (PAHs) in water using DGT technology were monitored. The concentration of PAHs in the water to be tested was 10 μg / L, and the ionic strengths (as NaCl) of the aqueous solutions to be tested were 0, 0.01, 0.1, 0.25, and 0.5 mol / L, respectively.

[0111] Figure 4 This diagram shows the adsorption effect of the DGT device on polycyclic aromatic hydrocarbons (PAHs) at different ionic intensities in this embodiment. The results show that the PAH concentration (C) measured by DGT according to the formula is... DGT ) and the concentration of polycyclic aromatic hydrocarbons in aqueous solution (C soln The ratios remained stable, ranging from 0.8 to 1.2 (except for Ant), indicating that the ionic strength of the water body had no significant impact on the DGT measurement results.

[0112] Example 6

[0113] In this embodiment, the effect of aqueous solution under different pH conditions on the determination of polycyclic aromatic hydrocarbons in water using DGT technology was monitored. The concentration of polycyclic aromatic hydrocarbons in the water to be tested was 10 μg / L, and the pH of the aqueous solution to be tested was 4, 6, and 8.

[0114] Figure 5 This diagram shows the adsorption effect of the DGT device on polycyclic aromatic hydrocarbons (PAHs) at different pH values ​​in this embodiment. The results show that the PAH concentration (C) measured by DGT according to the formula is... DGT ) and the concentration of polycyclic aromatic hydrocarbons in aqueous solution (C soln The ratios remained stable, ranging from 0.8 to 1.2, indicating that the pH of the water body between 4 and 8 had no significant impact on the DGT measurement results.

[0115] Example 7

[0116] In this embodiment, the effects of different soluble organic matter (DOM) concentrations in the aqueous solution on the determination of polycyclic aromatic hydrocarbons (PAHs) in water using DGT technology were monitored. The concentration of PAHs in the water to be tested was 10 μg / L, and the concentrations of soluble organic matter (DOM) in the aqueous solution to be tested were 0, 2, 5, 10, 15, and 20 mg / L.

[0117] Figure 6 This diagram shows the adsorption effect of the DGT device on polycyclic aromatic hydrocarbons (PAHs) at different soluble organic matter (DOM) concentrations in this embodiment. The results show that the concentrations of PAHs (Nap, Acy, Ace, Flu, Phe, Ant) measured by DGT according to the formula (C) DGT ) and the concentration of polycyclic aromatic hydrocarbons in aqueous solution (C soln The ratio remained stable within the range of 0.8-1.2, indicating that soluble organic matter in the water body had no significant impact on the DGT determination results of these substances.

[0118] Comparative Example 1

[0119] The outer shell is a crucial component of the DGT device. If the shell material causes significant adsorption of the analyte, it will affect the diffusion of the target substance to the adsorption membrane during the DGT measurement process, thus impacting the accuracy of the DGT results. This comparative example selected existing DGT shell materials such as ABS plastic, as well as common metals like aluminum, aluminum alloys, copper, brass, and stainless steel, to conduct adsorption experiments on polycyclic aromatic hydrocarbons (PAHs). The specific implementation steps are as follows:

[0120] (1) Place ABS plastic and different metal materials into brown bottles containing 100 mL of a mixed solution of 8 polycyclic aromatic hydrocarbons at 50 μg / L, and shake at 200 r / min at 25 °C for 24 hours.

[0121] (2) Before and after the experiment, water samples were taken from the brown bottle for measurement to determine the concentration of each polycyclic aromatic hydrocarbon in the water sample and calculate its amount of substance.

[0122] (3) Use the following formula to calculate the percentage of the amount of the target substance adsorbed by different materials in 24 hours.

[0123]

[0124] Where M1 is the amount of each polycyclic aromatic hydrocarbon in the aqueous solution before the experiment, and M2 is the amount of each polycyclic aromatic hydrocarbon in the aqueous solution 24 hours after adsorption.

[0125] Figure 7This diagram illustrates the 24-hour adsorption effects of different materials on various polycyclic aromatic hydrocarbons (PAHs) in this comparative example. The results show that aluminum, aluminum alloys, and stainless steel exhibit less adsorption of PAHs than ABS, brass, and copper. Specifically, aluminum and aluminum alloys adsorb less than 10% of PAHs, while stainless steel adsorbs less than 12% of all PAHs (except Pyr), making it suitable as the shell material for DGT (Digital Tariff Gel) devices for PAH measurement. Brass and copper adsorb less than ABS plastic, but still adsorb more than 20% of some PAHs, while ABS plastic adsorbs a large amount of PAHs, reaching 20-50% in 24 hours. Considering the cost and lightweight nature of metals, making them easier to carry for field experiments, aluminum was chosen for the shell of the DGT device when measuring PAHs in water.

[0126] Comparative Example 2

[0127] The outer shell is a crucial component of the DGT device. If the shell causes significant adsorption of the analyte, it will affect the diffusion of the target substance to the adsorption membrane during the DGT measurement, thus impacting the accuracy of the results. This comparative example utilizes both an existing plastic DGT shell and a designed aluminum shell to construct a DGT for the potential adsorption determination of polycyclic aromatic hydrocarbons (PAHs). The specific implementation steps are as follows:

[0128] (1) Build two types of DGT devices, using ABS plastic shells and metal aluminum shells respectively.

[0129] (2) Place the two apparatuses into a brown bottle containing a 100 mL solution of 8 polycyclic aromatic hydrocarbons at 50 μg / L and shake at 200 r / min at 25 °C for 24 hours.

[0130] (3) Before and after the experiment, water samples were taken from the brown bottle and measured to determine the concentration of each polycyclic aromatic hydrocarbon in the water sample.

[0131] (4) After the experiment, the adsorbent in DGT was extracted and eluted by ultrasonication using 5 mL of acetonitrile.

[0132] (5) Calculate the percentage of the amount of the target substance adsorbed by the two devices using the following formula.

[0133] Adsorption percentage (%) = (Cse × V1) / ((Cb - Ca) × V2) × 100%

[0134] Wherein, Cb refers to the concentration of the target substance in aqueous solution before the experiment, Ca refers to the concentration of the target substance in aqueous solution after the experiment, Cse refers to the concentration of the eluent of the adsorbent gel extracted with acetonitrile, V1 refers to the volume of the eluent, and V2 refers to the volume of the target substance in aqueous solution.

[0135] Figure 8The diagram shows the adsorption effects of the two devices on various polycyclic aromatic hydrocarbons (PAHs) in this comparative example. The results indicate that the aluminum shell adsorbs fewer PAHs than the ABS shell. The ABS plastic adsorbs a large amount of PAHs, which hinders the formation of a diffusion gradient between the filter and diffusion membranes and the capture by the adsorption membranes when the DGT is placed, thus affecting the measurement results. Therefore, aluminum is chosen for the shell of the DGT device when measuring PAHs in water.

[0136] Comparative Example 3

[0137] The filter membrane is a crucial component of the DGT (Digital Glucose Tolerance) device. If the filter membrane adsorbs the analyte compound, it will affect the diffusion of the target substance to the adsorbed membrane during the DGT measurement process, thus impacting the accuracy of the DGT results. This comparative example selected eight common filter membranes to determine the potential adsorption of polycyclic aromatic hydrocarbons (PAHs). The specific implementation steps are as follows:

[0138] (1) Eight types of filter membranes were selected, namely cellulose acetate microporous filter membrane (CA), mixed cellulose filter membrane (MCE), nylon filter membrane (Nylon), Nuclepore track etched membrane (PC), polyethersulfone membrane (PES), polypropylene filter membrane (PP), polytetrafluoroethylene membrane (PTFE) and polyvinylidene fluoride filter membrane (PVDF). Before the adsorption experiment, the filter membranes were soaked in 0.01 mol / L NaCl for at least 24 hours.

[0139] (2) Place the eight filter membranes into a brown bottle containing a mixed solution of eight polycyclic aromatic hydrocarbons at 50 μg / L for 10 mL and shake at 200 r / min at 25 °C for 24 hours.

[0140] (3) Before and after the experiment, water samples were taken from the brown bottle and measured to determine the concentration of each polycyclic aromatic hydrocarbon in the water sample.

[0141] (4) Calculate the adsorption percentage of the target substance by various filter membranes using the following formula.

[0142] Adsorption percentage (%) = (Cb - Ca) / Cb × 100%

[0143] Where Cb refers to the concentration of the target substance before the experiment, and Ca refers to the concentration of the target substance after the experiment.

[0144] Figure 9The diagram shows the adsorption effects of different filter membranes on various polycyclic aromatic hydrocarbons (PAHs) in this comparative example. According to the results, the Nuclepore track-etched membrane (PC) exhibits the lowest adsorption of PAHs (<10%). The other seven filter membranes adsorb a large amount of PAHs, which will hinder the process of the target substance forming a diffusion gradient between the filter membrane and the diffusion membrane and being captured by the adsorption membrane when it is assembled into a DGT device, thus affecting the measurement results. Therefore, the Nuclepore track-etched membrane (PC) is selected as the filter membrane in the DGT device when measuring PAHs in water.

[0145] Comparative Example 4

[0146] In this comparative example, the effect of aqueous solutions on the determination of polycyclic aromatic hydrocarbons (PAHs) in water by MIP-DGT and HLB-DGT under different pH conditions was monitored. The concentration of PAHs in the water to be tested was 10 μg / L, and the pH values ​​of the aqueous solutions were 4, 6, and 8, respectively.

[0147] The HLB adsorption membrane is fabricated using the same steps as the MIP adsorption membrane in Example 1, except that the MIP particles are replaced with HLB resin material.

[0148] Figure 10 This is a graph showing the adsorption effect of two DGT devices on polycyclic aromatic hydrocarbons (PAHs) at different pH values ​​in this comparative example. The results show that the PAH concentration (C) measured by DGT and calculated by MIP-DGT according to the formula is... DGT ) and the concentration of polycyclic aromatic hydrocarbons in aqueous solution (C soln The ratios remained stable, ranging from 0.8 to 1.2; while the concentration of polycyclic aromatic hydrocarbons (PAHs) measured by DGT at an aqueous solution pH of 4 remained stable. DGT ) and the concentration of polycyclic aromatic hydrocarbons in aqueous solution (C soln The ratio decreased significantly, to only 0.3-0.8, indicating that the pH of the water body between 4 and 8 had no significant effect on the measurement results of MIP-DGT, while acidic conditions affected the measurement results of HLB-DGT. MIP-DGT is superior to HLB-DGT in practical applications.

Claims

1. A DGT device for monitoring polycyclic aromatic hydrocarbons, characterized in that, The device includes a filter membrane, a diffusion membrane, an adsorption membrane, and a shell for fixing the filter membrane, diffusion membrane, and adsorption membrane. The shell is made of metal, including aluminum or aluminum alloy. The filter membrane is a Nuclepore track-etched membrane, the diffusion membrane is an agarose diffusion membrane, and the adsorption membrane is an agarose membrane containing molecularly imprinted compound particles. The polycyclic aromatic hydrocarbon includes one or more of naphthalene, acenaphthene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene.

2. The application of the DGT device for monitoring polycyclic aromatic hydrocarbons as described in claim 1 in the monitoring of polycyclic aromatic hydrocarbons.

3. A method for monitoring polycyclic aromatic hydrocarbons based on DGT technology, characterized in that, The method utilizes the DGT device for monitoring polycyclic aromatic hydrocarbons as described in claim 1 to perform adsorption and monitoring of polycyclic aromatic hydrocarbons. After monitoring, the adsorption membrane is eluted with an eluent to obtain an eluent, and then the concentration of polycyclic aromatic hydrocarbons in the eluent is measured.

4. The method for monitoring polycyclic aromatic hydrocarbons based on DGT technology according to claim 3, characterized in that, The elution conditions were: using acetonitrile as the eluent and sonicating for 30 ± 2 min.

5. The method for monitoring polycyclic aromatic hydrocarbons based on DGT technology according to claim 4, characterized in that, The method specifically includes the following steps: (1) Place the DGT device into the water body to be tested for monitoring of polycyclic aromatic hydrocarbons; (2) Recovery and elution of adsorption membrane: After removing the DGT device from the water body to be tested, rinse the device with pure water, remove the adsorption membrane and place it in a brown glass bottle, add eluent to obtain the eluent; (3) Determination of polycyclic aromatic hydrocarbons: The concentration of polycyclic aromatic hydrocarbons in the eluent obtained in step (2) was determined by high performance liquid chromatography-ultraviolet / fluorescence detection. (4) Calculation of the adsorption capacity of polycyclic aromatic hydrocarbons on the adsorption membrane: The adsorption capacity of polycyclic aromatic hydrocarbons on the MIP adsorption membrane is calculated according to the following formula (1). （1） Where M refers to the mass of polycyclic aromatic hydrocarbons adsorbed on the adsorption membrane, in ng; Ce refers to the concentration of polycyclic aromatic hydrocarbons in the eluent, in ng / mL; Vg refers to the volume of the adsorption membrane, in mL; Ve refers to the volume of the eluent, in mL; and Fe refers to the elution efficiency of polycyclic aromatic hydrocarbons on the adsorption membrane. (5) Calculation of DGT concentration: According to Fick's first diffusion law, the amount of analyte adsorbed on the adsorption membrane obtained in step (4) is converted into the concentration of DGT by formula (2). （2） Among them, C DGT Δg is the concentration of polycyclic aromatic hydrocarbons (PAHs) measured by the DGT device, in ng / mL; Δg is the thickness of the diffusion layer (including the filter membrane and the diffusion membrane), in cm; D is the diffusion coefficient of PAHs in the diffusion membrane, in cm. 2 / s; A is the window area of ​​the DGT device, in cm². 2 t is the placement time of the DGT device, in seconds.

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