Device for collecting and pre-treating microplastics in urine

Abstract

The invention discloses a device for collecting and pre-treating microplastics in urine, and belongs to the technical field of pre-treatment and analysis and detection. The device comprises seven functional parts, namely a urine collecting horn mouth, a urine collector, a large-caliber filter membrane bottom support, a small-caliber filter membrane bottom support, a waste liquid bottle, a vacuum pump and a stainless steel buckle, the whole device is made of a poly-4-methyl-1-pentene (PMP) material or a stainless steel material, and interference on detection of micro-plastics in urine is effectively avoided. The device has the functions of urine collection and pretreatment at the same time, pretreatment operation can be completed without transferring a urine sample, and pollution and sample loss are reduced to the maximum extent. Aiming at the characteristic that a urine matrix is complex, a matched pretreatment reagent adding and digestion process is designed, urine is digested through hydrogen peroxide and potassium hydroxide reagents in a specific proportion, and matrix interference such as protein and mineral substances can be effectively removed. Due to the unique V-shaped collector design of the device, the filter membrane can be converted from a large caliber to a small caliber, and the detection time is shortened.

Description

Technical Field

[0001] This invention relates to the fields of pretreatment technology and analytical detection technology, and in particular to a device for collecting and pretreatment of microplastics in urine. Background Technology

[0002] A growing body of scientific research indicates that humans can be exposed to microplastics through a variety of sources and pathways. Besides exposure to drinking water, microplastics have also been detected in various foods and in the air. Humans can be exposed to microplastics through oral ingestion, inhalation, and skin contact, and microplastics have already penetrated various parts of the human body.

[0003] There is limited literature on human exposure levels. Microplastics have been detected in various human tissues, organs, and metabolites (placenta, lungs, liver, kidneys, colon, meconium, blood, urine, feces, sputum, etc.). As a high-molecular-weight substance, microplastics are difficult to degrade and exhibit physical, chemical, and biological toxicity to humans.

[0004] Currently, the collection and detection of microplastics are mostly concentrated in environmental water bodies such as oceans and lakes. Research on the presence of microplastics in human biological samples is relatively limited, with insufficient research scope and sample size, resulting in limited data. To further investigate the presence of microplastics in human biological samples, it is necessary to establish accurate and reliable pretreatment and detection methods, and to conduct further detection on a larger scale of representative biological samples. This will provide more data support for assessing the health impacts of microplastics.

[0005] Existing technologies include a microplastic detection pretreatment device, but this device lacks sampling functionality. Samples must be transferred from the sampling container into the pretreatment device, a process prone to contamination. Furthermore, this pretreatment device only provides membrane filtration, suitable for relatively clean liquid samples such as tap water and seawater. For complex liquid samples like urine, membrane clogging or microplastic embedding on the membrane matrix can occur during sample processing, significantly impacting detection accuracy.

[0006] In addition, there is a pretreatment method for detecting microplastics in marine fish. This method is mostly focused on high-protein, high-fat solid samples such as fish meat. The pretreatment method requires numerous reagents, involves complex steps, and is time-consuming. However, there is a lack of dedicated pretreatment experimental procedures and methods for detecting microplastics in urine, which cannot meet the needs of accurate detection of microplastics in human urine. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and address the problems in related technologies by providing a device for collecting and pre-treating microplastics in urine. This device comprises seven functional components: a urine collection nozzle, a urine collector, a large-diameter filter membrane base, a small-diameter filter membrane base, a waste bottle, a vacuum pump, and stainless steel clips. The entire device is constructed of poly(4-methyl-1-pentene) (PMP) or stainless steel, effectively avoiding interference with the detection of microplastics in urine. This invention simultaneously performs urine collection and pre-treatment functions, completing the pre-treatment operation without transferring the urine sample, minimizing contamination and sample loss. Considering the complex matrix characteristics of urine, a matching pre-treatment reagent addition and digestion process is designed. The urine is digested using a specific ratio of hydrogen peroxide and potassium hydroxide reagents, effectively removing matrix interference such as proteins and minerals. The device's unique "V"-shaped collector design enables the conversion of the filter membrane from a large-diameter to a small-diameter diameter, shortening the detection time. The stainless steel filter membrane is reusable, reducing experimental costs. This device is highly practical and can meet the needs of quantitative and qualitative detection of microplastics, providing reliable technical support for the accurate detection of microplastics in human urine. It is suitable for conducting microplastic exposure studies in different populations and environments.

[0008] The first aspect of the present invention is to provide an apparatus for collecting and pre-treating microplastics in urine, comprising a urine collection funnel (1), a urine collector (2), a large-diameter filter membrane base (3), a small-diameter filter membrane base (4), a waste bottle (5), a vacuum pump (6), and a stainless steel buckle (7); the urine collection funnel (1) is detachably and fixedly connected to the second port (201) of the urine collector (2) by the stainless steel buckle (7); the large-diameter filter membrane base (3) is detachably and fixedly connected to the first port (202) of the urine collector (2) away from the urine collection funnel (1) by the stainless steel buckle (7); a stainless steel filter membrane (301) can be placed inside the large-diameter filter membrane base (3), and a waste liquid outlet (302) is provided on the large-diameter filter membrane base (3). The small-diameter filter membrane base (4) can be detachably and fixedly connected to the port (201) of the urine collector (2) by a stainless steel buckle (7). An alumina filter membrane (401) can be placed inside the small-diameter filter membrane base (4). A waste liquid outlet (402) is provided on the small-diameter filter membrane base (4). An inlet (501) and a outlet (502) are provided on the waste liquid bottle (5). The waste liquid outlet (302) and the waste liquid outlet (402) can be connected to the inlet (501) to receive waste liquid from the large-diameter filter membrane base (3) or the small-diameter filter membrane base (4). The vacuum pump (6) is connected to the waste liquid bottle (5) to provide negative pressure filtration power so that urine or microplastic suspension can pass through the filter membrane quickly to achieve microplastic enrichment.

[0009] Preferably, the urine collection funnel (1) and the urine collector (2) are both made of poly(4-methyl-1-pentene) (PMP) material; the urine collection funnel (1) has an flared structure; the urine collector (2) has a transparent structure and is provided with precise graduations on its bottle body.

[0010] Preferably, the pore size of the stainless steel filter membrane (301) is 1.0 μm; the stainless steel filter membrane (301), the large-diameter filter membrane base (3), the small-diameter filter membrane base (4), and the stainless steel buckle (7) are all made of stainless steel.

[0011] Preferably, the urine collector (2) has a "V" shaped structure, with a first port (202) at the end near the urine collection funnel (1), and the diameter of the first port (202) is larger than the diameter of the second port (201) at the end away from the urine collection funnel (1).

[0012] Preferably, the waste liquid bottle (5) is also provided with an exhaust port, and the vacuum pump (6) is connected to the exhaust port through a pipe; the drain port (502) is provided with a liquid control valve.

[0013] A second aspect of the present invention is to provide a method for collecting and pre-treating microplastics in urine based on the device of the first aspect, comprising the following steps:

[0014] S1. Sampling preparation: Connect the urine collection funnel (1) and the port (201) of the urine collector (2) with stainless steel buckles (7); place a stainless steel filter membrane (301) on the large-diameter filter membrane base (3), and fix the end of the large-diameter filter membrane base (3) away from the urine collection funnel (1) with stainless steel buckles (7) to seal it, and close the waste liquid outlet (302).

[0015] S2, Urine collection: The subjects used the device assembled in step S1 to collect urine directly and recorded the urine volume through the scale on the urine collector (2) bottle.

[0016] S3. Urine digestion: Open the stainless steel buckle (7) at the connection between the urine collection flare (1) and the urine collector (2), and remove the urine collection flare (1); add reagent 1 to the urine collector (2), wherein the reagent 1 is 30% hydrogen peroxide, and the volume ratio of the added reagent to the urine volume is 1:1, mix well and let stand for 30 minutes; then add reagent 2 to the urine collector (2), wherein the reagent 2 is potassium hydroxide, and the amount added is such that the mass fraction of potassium hydroxide in the digestion solution is 5%, mix well and let stand for 30 minutes to complete the urine digestion; the total time for the urine digestion is 1 hour;

[0017] S4. Microplastic enrichment: Connect the waste liquid outlet (302) on the large-diameter filter membrane base (3) to the liquid inlet (501) of the waste liquid bottle (5), turn on the vacuum pump (6), and under negative pressure, the digested urine is filtered through the stainless steel filter membrane (301), and microplastics are enriched on the stainless steel filter membrane (301).

[0018] Preferably, the method further includes:

[0019] S5. Quantitative detection of microplastics: Remove the stainless steel filter membrane (301), observe the appearance and morphology of microplastics under a microscope or electron microscope, and count the number.

[0020] Preferably, in step S5, the microscope is an optical microscope with a magnification of 100-400 times; the electron microscope is a scanning electron microscope.

[0021] Preferably, the method further includes:

[0022] S6. Qualitative detection of microplastics: Cover the port (201) of the urine collector (2) with an alumina filter membrane (401), and fix the small-diameter filter membrane base (4) to the port (201) of the urine collector (2) with a stainless steel buckle (7) to seal it; invert the entire device so that the small-diameter filter membrane base (4) is at the bottom and the large-diameter filter membrane base (3) is at the top; open the stainless steel buckle (7) at the connection between the large-diameter filter membrane base (3) and the urine collector (2), and remove the large-diameter filter membrane base (3); slightly bend the stainless steel filter membrane (301) and place it in the urine collector. In the chamber of apparatus (2), add ultrapure water to rinse the stainless steel filter membrane (301) and rinse the microplastics on the filter membrane into the chamber. Then remove the stainless steel filter membrane (301). Connect the waste liquid outlet (402) on the bottom support (4) of the small diameter filter membrane to the liquid inlet (501) of the waste liquid bottle (5). Turn on the vacuum pump (6). Under negative pressure, the microplastic suspension is filtered through the alumina filter membrane (401), and the microplastics are enriched on the alumina filter membrane (401). Take out the alumina filter membrane (401) and dry it. Under micro-infrared spectroscopy or micro-Raman spectroscopy, the type of microplastics is determined by characteristic spectrum.

[0023] Preferably, in step S6, the amount of ultrapure water added is 2-3 times the volume of urine; the pore size of the alumina filter membrane (401) is 0.22-0.45 μm.

[0024] The beneficial effects of the device of the present invention:

[0025] 1. Integrates collection and processing, reducing pollution and losses.

[0026] This invention's device combines urine sample collection and pretreatment functions, allowing for pretreatment of urine without transfer, minimizing contamination and loss during processing. The entire device is constructed from poly(4-methyl-1-pentene) (PMP) or stainless steel, and the accuracy of test results is ensured through dual marking using specific materials and colors. Except for the alumina filter membrane, all other components are washable and reusable, reducing experimental costs.

[0027] 2. Highly practical and widely applicable.

[0028] This device is highly practical. For quantitative detection, it can be achieved after preliminary sample processing, allowing for the analysis of microplastic morphology and quantity under a microscope or electron microscope. For qualitative and quantitative detection, further sample processing can be performed, collecting microplastics through an alumina membrane. Qualitative and quantitative analysis of microplastics larger than 1 micrometer on the membrane can then be conducted using a micro Raman spectroscopy instrument. This device meets the requirements of commonly used instruments for microplastic detection and has a wide range of applications.

[0029] 3. Easy to use, convenient and efficient

[0030] The urine collection nozzle (1) is made of poly(4-methyl-1-pentene) (PMP) with a flared design, which prevents sample spillage during collection. Compared to glass, this material is less prone to breakage, making it safer and more convenient to use. The collector is made of poly(4-methyl-1-pentene) (PMP), and the urine sample volume can be accurately recorded through the scale on the transparent bottle, eliminating the need for additional measuring tools and simplifying the operation.

[0031] 4. Unique structural design shortens testing time.

[0032] The urine collector (2) features a unique “V” shape design, which enables the filter membrane to be transformed from a large-diameter to a small-diameter membrane, greatly reducing the filtration area of ​​the filter membrane. This shortens the detection time required for the entire filter membrane and improves detection efficiency.

[0033] 5. The filter membrane and components are durable and low in cost.

[0034] The stainless steel membrane is corrosion-resistant and will not be damaged by urine digestion reagents. It can be reused after cleaning, which greatly reduces experimental costs compared to disposable filter membranes. Other components, such as the urine collection nozzle and urine collector, can also be reused, further reducing experimental consumable expenses.

[0035] 6. The digestion reagents are readily available and the digestion effect is good.

[0036] The digestion reagents used in this invention are 30% hydrogen peroxide and potassium hydroxide, both of which are commonly used laboratory reagents and readily available. Adjusting the reagent dosage according to the urine volume ensures complete urine digestion, effectively removes matrix interference, and improves detection accuracy.

[0037] 7. Simple operation and short processing time

[0038] The entire process, from sample collection to pretreatment, is quick and easy to operate, requiring no complex professional skills. Ordinary laboratory personnel can complete the operation, making it suitable for large-scale sample testing. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the sample collection and pretreatment device provided in an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of a stainless steel buckle structure provided in an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the waste liquid collection device provided in an embodiment of the present invention;

[0043] Figure 4 The image provided here shows the detection effect of microplastics after digestion using this formula, as provided in an embodiment of the present invention. Figure 4 (a) The detection effect of microplastics after digestion using the formulation of the present invention; Figure 4 (b) The detection effect of microplastics after digestion without using the formulation of this invention;

[0044] Figure 5 This is a schematic diagram illustrating the types of microplastic particles detected in a urine sample according to an embodiment of the present invention.

[0045] Reference numerals: 1-Urine collection bell mouth; 2-Urine collector; 201-Second port; 202-First port; 3-Large diameter filter membrane base; 301-Stainless steel filter membrane; 302-Waste liquid outlet; 4-Small diameter filter membrane base; 401-Alumina filter membrane; 402-Waste liquid outlet; 5-Waste liquid bottle; 501-Inlet; 502-Outlet; 6-Vacuum pump; 7-Stainless steel buckle. Detailed Implementation

[0046] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] The term “about” is used here in conjunction with numerical values ​​to include normal variation in measurements as expected by those skilled in the art, and should be understood to have the same meaning as “approximately” and to cover typical error margins, such as ±5% of the specified value.

[0050] Terms such as “one,” “an,” and “the” are not intended to refer to a single entity, but rather to include general categories that can be illustrated using specific examples.

[0051] Unless otherwise stated, any amount (e.g., concentration) of a component in a composition given as a percentage (%) refers to a weight percentage per volume.

[0052] like Figure 1 As shown, Figure 1The diagram shows the overall structure of the device of the present invention. The device includes a urine collection funnel (1), a urine collector (2), a large-diameter filter membrane base (3), a stainless steel filter membrane (301), a small-diameter filter membrane base (4), an alumina filter membrane (401), a waste liquid bottle (5), a vacuum pump (6), and a stainless steel buckle (7). The urine collection funnel (1) is connected to the port (201) of the urine collector (2) via the stainless steel buckle (7); the large-diameter filter membrane base (3) is connected to the lower end of the urine collector (2) via the stainless steel buckle (7), and a stainless steel filter membrane (301) is placed inside the large-diameter filter membrane base (3). A waste liquid outlet (302) is provided on the side of the large-diameter filter membrane base (3); the small-diameter filter membrane base (4) can be connected to the port (201) of the urine collector (2), and an alumina filter membrane is placed inside the small-diameter filter membrane base (4). The filter membrane (401) has a waste liquid outlet (402) on the side of the small-diameter filter membrane base (4); the waste liquid bottle (5) has an inlet (501) and a drain (502). The waste liquid outlet (302) and the waste liquid outlet (402) can be connected to the inlet (501) through pipes. The inlet (501) is used to receive waste liquid from the large-diameter filter membrane base (3) or the small-diameter filter membrane base (4); the vacuum pump (6) is connected to the exhaust port of the waste liquid bottle (5) through pipes; the drain (502) is equipped with a control valve. The urine collector (2) has a "V" shaped structure, with the upper port diameter larger than the lower port diameter, and the bottle body has graduations.

[0053] like Figure 2 As shown, Figure 2 This is a schematic diagram of the stainless steel buckle structure used in the device of the present invention. The stainless steel buckle (7) includes a buckle body, a movable claw, and a fixing bolt. The buckle body has an arc-shaped structure, which is adapted to the connection port of each component; the movable claw is located at one end of the buckle body and can rotate around the connecting shaft; the fixing bolt is located at the other end of the buckle body. When the movable claw is engaged, tightening the fixing bolt can achieve tight fixation between the components and ensure the sealing of the connection.

[0054] like Figure 3 As shown, Figure 3 This is a schematic diagram of the waste liquid collection part of the device of the present invention, which includes a waste liquid bottle (5) and a vacuum pump (6). The waste liquid bottle (5) is a sealed structure with an inlet (501), an exhaust port and a drain port (502) on the top. The inlet (501) is used to connect to the waste liquid outlet (302) or the waste liquid outlet (402) to receive waste liquid from the large-diameter filter membrane base (3) or the small-diameter filter membrane base (4). The exhaust port is connected to the vacuum pump (6) through a pipe. The drain port (502) is equipped with a liquid control valve. When the vacuum pump (6) is working, it can extract the air in the waste liquid bottle (5) to form a negative pressure environment, so that urine or microplastic suspension can quickly pass through the filter membrane to achieve the enrichment of microplastics.

[0055] Example 1

[0056] This embodiment provides a device for collecting and pre-treating microplastics in urine, including seven functional components: a urine collection funnel (1), a urine collector (2), a large-diameter filter membrane base (3), a small-diameter filter membrane base (4), a waste liquid bottle (5), a vacuum pump (6), and a stainless steel buckle (7).

[0057] The structure and connection relationships of each component include:

[0058] The urine collection nozzle (1) and the second port (201) of the urine collector (2) are detachably and fixedly connected by a stainless steel buckle (7). The urine collection nozzle (1) is designed with an flared opening to facilitate urine collection by the test subjects and to prevent splashing during the collection process;

[0059] The large-diameter filter membrane base (3) and the first port (202) of the urine collector (2) away from the urine collection funnel (1) are detachably and fixedly connected by a stainless steel buckle (7); a stainless steel filter membrane (301) can be placed inside the large-diameter filter membrane base (3). The pore size of the stainless steel filter membrane (301) is 1.0μm. Under non-negative pressure, the collected urine will not pass through the filter membrane to reach the lower cavity of the large-diameter filter membrane base (3); a waste liquid outlet (302) is provided on the large-diameter filter membrane base (3). The waste liquid outlet (302) can be connected to the inlet (501) of the waste liquid bottle (5) for discharging the filtered waste liquid;

[0060] The small-diameter filter membrane base (4) can be detachably and fixedly connected to the second port (201) of the urine collector (2) via a stainless steel buckle (7); an alumina filter membrane (401) can be placed inside the small-diameter filter membrane base (4), the pore size of the alumina filter membrane (401) is 0.22-0.45μm, used for the fine enrichment of microplastics for subsequent qualitative detection; a waste liquid outlet (402) is provided on the small-diameter filter membrane base (4), and the waste liquid outlet (402) can be connected to the inlet (501) of the waste liquid bottle (5);

[0061] The waste liquid bottle (5) is provided with an inlet (501), an exhaust port and a drain port (502). The inlet (501) is used to receive waste liquid from the large-diameter filter membrane base (3) or the small-diameter filter membrane base (4). The exhaust port is connected to the vacuum pump (6) through a pipe. The drain port (502) is equipped with a liquid control valve. The vacuum pump (6) is used to provide negative pressure filtration power so that urine or microplastic suspension can pass through the filter membrane quickly to achieve microplastic enrichment.

[0062] The stainless steel buckle (7) is used to achieve a detachable and fixed connection between the components. The connection is tight and the sealing is good, which can avoid leakage or contamination during sampling and processing.

[0063] In a preferred embodiment, both the urine collection nozzle (1) and the urine collector (2) are made of poly(4-methyl-1-pentene) (PMP). This material has excellent mechanical properties, resulting in high mechanical strength in molded products; it is chemically stable and resistant to acids and alkalis; it has high light transmittance and can be colored to create devices with specific colors. During the detection process, the dual marking of the specific material and color effectively monitors and controls interference introduced by the sampling vessel. Furthermore, compared to glass, this material is less prone to breakage; compared to stainless steel, it is transparent and corrosion-resistant, allowing for accurate measurement of the collected urine sample volume via the bottle's markings.

[0064] In a preferred embodiment, the stainless steel filter membrane (301), the large-diameter filter membrane base (3), the small-diameter filter membrane base (4), and the stainless steel buckle (7) are all made of stainless steel. Stainless steel is corrosion-resistant, and the urine digestion reagent will not damage it. It can be reused after cleaning, reducing experimental costs.

[0065] In a preferred embodiment, the alumina filter membrane (401) is a disposable component made of high-purity alumina, which has good chemical stability and will not interfere with the qualitative detection of microplastics.

[0066] In a preferred embodiment, the urine collector is specially designed, namely, the urine collector (2) has a "V" shaped structure, with a first port (202) at the end near the urine collection funnel (1), the diameter of which is larger than the diameter of the second port (201) at the end away from the urine collection funnel (1). This unique "V" shaped design realizes the transformation of the filter membrane from a large opening to a small diameter, greatly reducing the filtration area of ​​the filter membrane, thereby shortening the detection time required for the entire filter membrane.

[0067] Example 2

[0068] This embodiment provides a method for collecting and pre-treating microplastics in urine using the device of Embodiment 1. The method includes the following steps:

[0069] S1. Sampling preparation: Connect the urine collection funnel (1) to the second port (201) of the urine collector (2) with a stainless steel buckle (7); place a stainless steel filter membrane (301) on the large-diameter filter membrane base (3), and fix the end of the large-diameter filter membrane base (3) away from the urine collection funnel (1) to the urine collector (2) with a stainless steel buckle (7) to seal it, and close the waste liquid outlet (302).

[0070] S2. Urine collection: The subjects used the device assembled in step S1 to collect urine directly and recorded the urine volume through the scale on the urine collector (2) bottle.

[0071] S3. Urine digestion: Open the stainless steel buckle (7) at the connection between the urine collection nozzle (1) and the urine collector (2), and remove the urine collection nozzle (1); add reagent 1 to the urine collector (2), which is 30% hydrogen peroxide, with an addition volume ratio of 1:1 to the urine volume, mix well, and let stand for 30 minutes; then add reagent 2 to the urine collector (2), which is potassium hydroxide, with the addition amount making the mass fraction of potassium hydroxide in the digestion solution 5%, mix well, and let stand for 30 minutes to complete the urine digestion. The total digestion time is 1 hour. This digestion step can effectively remove matrix interference such as protein, minerals, and colloidal substances in the urine, prevent filter membrane blockage, and prevent the encapsulation of interfering substances on microplastics.

[0072] S4. Microplastic enrichment: Connect the waste liquid outlet (302) on the large-diameter filter membrane base (3) to the liquid inlet (501) of the waste liquid bottle (5), turn on the vacuum pump (6), and under negative pressure, the digested urine is filtered through the stainless steel filter membrane (301), and microplastics are enriched on the stainless steel filter membrane (301).

[0073] S5. Quantitative detection of microplastics (optional): Remove the stainless steel filter membrane (301) and observe the appearance and morphology of microplastics under an optical microscope or scanning electron microscope with a magnification of 100-400x and count the number of microplastics.

[0074] S6. Qualitative detection of microplastics (optional): Cover the port (201) of the urine collector (2) with an alumina filter membrane (401), and fix the small-diameter filter membrane base (4) to the port (201) of the urine collector (2) with a stainless steel buckle (7) to seal it; invert the entire device so that the small-diameter filter membrane base (4) is at the bottom and the large-diameter filter membrane base (3) is at the top; open the stainless steel buckle (7) at the connection between the large-diameter filter membrane base (3) and the urine collector (2), and remove the large-diameter filter membrane base (3); slightly bend the stainless steel filter membrane (301) and place it in the cavity of the urine collector (2), and add 2-3 times the volume of urine. The stainless steel filter membrane (301) is rinsed with ultrapure water to flush the microplastics on the filter membrane into the cavity, and then the stainless steel filter membrane (301) is removed. The waste liquid outlet (402) on the small diameter filter membrane base (4) is connected to the liquid inlet (501) of the waste liquid bottle (5), and the vacuum pump (6) is turned on. Under the action of negative pressure, the microplastic suspension is filtered through the alumina filter membrane (401), and the microplastics are enriched on the alumina filter membrane (401). The alumina filter membrane (401) is removed and dried. The type of microplastics is determined by characteristic spectra under a micro-infrared spectrometer or a micro-Raman spectrometer.

[0075] The working principle of the device for collecting and pre-treating microplastics in urine according to the preferred embodiment mainly includes four parts: sampling principle, digestion principle, negative pressure enrichment principle, and detection principle.

[0076] 1. Sampling principle

[0077] The device features a widened nozzle for easy urine collection and to prevent splashing. The urine collector is made of transparent PMP material and includes graduations for accurate real-time urine volume recording. Before sampling, all components are tightly connected by stainless steel clips to form a sealed sampling system, preventing contamination from microplastics in the external environment. Under non-negative pressure, the stainless steel filter membrane inside the large-diameter filter holder blocks impurities in the urine without allowing it to pass through, ensuring complete collection within the urine collector.

[0078] 2. Digestion Principle

[0079] To address the presence of proteins, minerals, and colloidal substances in urine, this invention employs a combination of 30% hydrogen peroxide and potassium hydroxide for digestion. Hydrogen peroxide, a strong oxidizing agent, can oxidize and decompose organic substances such as proteins in urine; potassium hydroxide, a strong alkali, promotes protein hydrolysis and dissolves minerals in urine. The two reagents are added in a specific ratio and order: hydrogen peroxide is added first and allowed to stand for 30 minutes to initially oxidize and decompose organic substances; then potassium hydroxide is added to achieve a mass fraction of 5%, and the mixture is allowed to stand for another 30 minutes to further promote matrix decomposition. The entire digestion process is gentle and efficient, effectively removing matrix interference, preventing filter membrane clogging and matrix-embedded microplastics during subsequent filtration, while preserving the structure of the microplastics and ensuring the accuracy of the test results.

[0080] 3. Negative pressure enrichment principle

[0081] After digestion, connect the waste liquid outlet of the large-diameter filter membrane base to the inlet of the waste liquid bottle and turn on the vacuum pump. When the vacuum pump is working, it extracts air from the waste liquid bottle, creating a negative pressure environment. Under this negative pressure, the digestion solution in the urine collector quickly passes through the stainless steel filter membrane. Microplastics in the urine, due to their larger particle size than the filter membrane pores, are enriched on the filter membrane surface, while the waste liquid enters the waste liquid bottle through the waste liquid outlet. For qualitative analysis, rinse the stainless steel filter membrane with ultrapure water to transfer the microplastics to the urine collector. Then, using an inverted device, the microplastic suspension is forced through the alumina filter membrane in the small-diameter filter membrane base under negative pressure, achieving fine enrichment of the microplastics and preparing for subsequent qualitative analysis.

[0082] 4. Detection Principle

[0083] For quantitative detection, stainless steel filter membranes enriched with microplastics can be directly observed under a microscope or electron microscope. By adjusting the magnification of the microscope, the morphology of the microplastics, such as fibrous, granular, and flake-like forms, can be clearly observed, and their quantity can be counted. For qualitative detection, dried alumina filter membranes enriched with microplastics can be detected under a micro-infrared spectroscopy or a micro-Raman spectroscopy. Different types of microplastics have unique characteristic spectra. By comparing the detected spectra with a standard spectral library, the type of microplastic, such as PP, PE, and PVC, can be determined.

[0084] Application Example 1: Quantitative Detection of Microplastics in Urine

[0085] 1. Device component parameters and preparation

[0086] (1) Urine collection bell mouth (1): Made of poly(4-methyl-1-pentene) (PMP), with an flare angle of 45°, a maximum diameter of 8cm and a minimum diameter of 3cm, which is compatible with the urine collector port (201).

[0087] (2) Urine collector (2): Made of poly(4-methyl-1-pentene) (PMP), with a “V” shape, an upper port diameter of 3cm, a lower port diameter of 1.5cm, a height of 20cm, a bottle body graduation accuracy of 1mL, and a maximum capacity of 100mL.

[0088] (3) Large-diameter filter membrane base (3): Made of 304 stainless steel, with a diameter of 1.5cm and a height of 5cm, and can hold a stainless steel filter membrane (301) with a diameter of 1.5cm.

[0089] (4) Stainless steel filter membrane (301): Made of 316 stainless steel, with a pore size of 1.0μm, a diameter of 1.5cm, and a thickness of 0.2mm.

[0090] (5) Small-diameter filter membrane base (4): Made of 304 stainless steel, with a diameter of 3cm and a height of 5cm, and can hold an alumina filter membrane (401) with a diameter of 3cm.

[0091] (6) Alumina filter membrane (401): Made of high-purity alumina, with a pore size of 0.22μm, a diameter of 3cm, and a thickness of 0.1mm.

[0092] (7) Waste liquid bottle (5): Made of glass, with a volume of 500mL, the diameter of the inlet (501) and outlet (502) is 0.5cm, and the diameter of the exhaust port is 0.3cm.

[0093] (8) Vacuum pump (6): A miniature diaphragm vacuum pump is used, with a negative pressure range of 0-0.09MPa and a power of 50W.

[0094] (9) Stainless steel buckle (7): Made of 304 stainless steel, the buckle body is 1cm wide, the movable claw is 2cm long, and the fixing bolt is 0.3cm in diameter.

[0095] (10) Source of each component: The urine collection bell mouth (1) and urine collector (2) are manufactured by injection molding and custom-produced by a plastic products company; the stainless steel filter membrane (301), large diameter filter membrane base (3), small diameter filter membrane base (4), and stainless steel buckle (7) are manufactured by precision casting and machining and custom-produced by a metal products company; the alumina filter membrane (401) is purchased from a filter membrane company; the waste liquid bottle (5) and vacuum pump (6) are purchased from a laboratory equipment company.

[0096] 2. Experimental Procedure

[0097] S1. Sampling preparation: Connect the urine collection funnel (1) to the port (201) of the urine collector (2) with stainless steel buckles (7); place a stainless steel filter membrane (301) on the large-diameter filter membrane base (3), and seal the large-diameter filter membrane base (3) to the lower end of the urine collector (2) with stainless steel buckles (7), and close the waste liquid outlet (302).

[0098] S2. Urine collection: Select a healthy adult male as the experimental subject, collect morning urine using the assembled device, and record the urine volume as 50 mL through the scale on the urine collector (2) bottle.

[0099] S3. Urine digestion: Open the stainless steel buckle (7) at the connection between the urine collection flare (1) and the urine collector (2), and remove the urine collection flare (1); add 50 mL of 30% hydrogen peroxide (reagent 1) to the urine collector (2), gently shake to mix, and let stand for 30 min; at this time, the total volume of the digestion solution is 100 mL. Add 5 g of potassium hydroxide (reagent 2) to the urine collector (2), mix, and let stand for 30 min to complete the urine digestion. The total digestion time is 1 h.

[0100] S4. Microplastic enrichment: Connect the waste liquid outlet (302) on the large-diameter filter membrane base (3) to the liquid inlet (501) of the waste liquid bottle (5) through a pipe, turn on the vacuum pump (6), adjust the negative pressure value to 0.05MPa, and under the action of negative pressure, the digested urine is filtered through the stainless steel filter membrane (301), and the microplastics are enriched on the stainless steel filter membrane (301). The filtration time is 10min.

[0101] S5. Quantitative detection of microplastics: Remove the stainless steel filter membrane (301), place it on a glass slide, observe the appearance and morphology of microplastics under an optical microscope with a magnification of 200x, and count the number.

[0102] Comparative Example 1

[0103] A comparative experiment was carried out using the pretreatment device for microplastic detection in the existing technology, and this device does not have a sampling function.

[0104] Experimental steps: Use a urine collection cup made of polyethylene to collect 5 mL of morning urine from the same experimental subject; transfer the urine to the existing pretreatment device, without performing digestion treatment, directly turn on the vacuum pump for filtration, and the filter membrane uses a cellulose filter membrane with a pore size of 1.0 μm; after filtration, remove the cellulose filter membrane, and observe the microplastic morphology and count the number under an optical microscope with the same magnification.

[0105] Result comparison and analysis: Table 1 shows the comparison of the microplastic quantitative detection results between Application Example 1 and Comparative Example 1.

[0106] Table 1

[0107]

[0108] As can be seen from Table 1, in Application Example 1, the device and method of the present invention were used for detection, the filter membrane was not blocked, the counted number of microplastics was 28, and the total time from sampling to completion of detection was 15 minutes; while in Comparative Example 1, the existing device and method were used, the filter membrane was severely blocked, the counted number of microplastics was only 8, and the total detection time was 40 minutes.

[0109] Figure 4 For the microplastic detection effect diagram after digestion using this formula, where Figure 4 (a) is the microplastic detection effect after digestion using the formula of the present invention; Figure 4 (b) is the microplastic detection effect without digestion using the formula of the present invention. This is because the digestion method supporting the device of the present invention effectively removes the matrix interference in urine, avoids filter membrane blockage, and thus can accurately enrich microplastics; at the same time, the device integrates collection and treatment, eliminates the need to transfer urine, reduces microplastic loss, and improves detection accuracy; the unique "V"-shaped collector design shortens the filtration and detection time. While the existing device has no sampling function, microplastic loss is likely to occur during the urine transfer process, and no digestion treatment is carried out, and the matrix in urine is likely to block the filter membrane, resulting in low detection result accuracy and long time consumption.

[0110] Qualitative and quantitative detection of microplastics in urine in Application Example 2

[0111] 1. Device component parameters and preparation: The device component parameters are the same as those in Application Example 1, and the processing sources of each component are also the same as those in Application Example 1.

[0112] 2. Experimental steps

[0113] S1-S4: The steps are the same as those in Example 1, collecting 50 mL of morning urine and completing digestion and microplastic enrichment.

[0114] S5. Quantitative detection of microplastics: The appearance and morphology of microplastics on the stainless steel filter membrane (301) were observed and the number was counted under a scanning electron microscope with a magnification of 400x. The result was 32 microplastics.

[0115] S6. Qualitative detection of microplastics: Cover the port (201) of the urine collector (2) with an alumina filter membrane (401) with a pore size of 0.45 μm. Fix the small-diameter filter membrane base (4) to the port (201) of the urine collector (2) with a stainless steel buckle (7) to seal it. Invert the entire device so that the small-diameter filter membrane base (4) is at the bottom and the large-diameter filter membrane base (3) is at the top. Open the stainless steel buckle (7) at the connection between the large-diameter filter membrane base (3) and the urine collector (2) and remove the large-diameter filter membrane base (3). Slightly bend the stainless steel filter membrane (301) and place it in the cavity of the urine collector (2). Add 100 mL of ultrapure water (2 times the volume of urine). Rinse the stainless steel filter membrane (301) by 100 times, gently shake the urine collector (2) to rinse the microplastics on the filter membrane into the cavity, and then remove the stainless steel filter membrane (301); connect the waste liquid outlet (402) on the small diameter filter membrane base (4) to the liquid inlet (501) of the waste liquid bottle (5) through a pipe, turn on the vacuum pump (6), adjust the negative pressure value to 0.04MPa, and under the action of negative pressure, the microplastic suspension is filtered through the alumina filter membrane (401), and the microplastics are enriched on the alumina filter membrane (401). The filtration time is 8min; take out the alumina filter membrane (401), place it in a constant temperature drying oven, and dry it at 60℃ for 30min; place the dried alumina filter membrane (401) on the sample stage of the micro Raman spectrometer, and perform qualitative analysis on the microplastics on the membrane. The detection wavelength is 532nm.

[0116] Comparative Example 2

[0117] A comparative experiment was conducted using existing pretreatment methods for detecting microplastics in vivo.

[0118] Experimental Procedure: Collect 50 mL of morning urine from the same subject using a polyethylene urine collection cup; add a mixed digestion reagent (nitric acid, perchloric acid, and sulfuric acid in a volume ratio of 3:1:1) to the urine and digest for 2 h under heating conditions; after digestion, transfer the digest to a centrifuge tube and centrifuge for 10 min at 5000 r / min; take the supernatant and filter it using a 0.45 μm cellulose membrane; after filtration, remove the cellulose membrane, dry it, and perform qualitative analysis using a micro Raman spectroscopy system with the same parameters.

[0119] Results Comparison and Analysis: Table 2 shows the comparison of qualitative and quantitative detection results of microplastics between Application Example 2 and Comparative Example 2.

[0120] Table 2

[0121]

[0122] As shown in Table 2, in Application Example 2, using the device and method of the present invention, the number of microplastics counted was 32, and the types of microplastics that could be identified included PP (polypropylene), PE (polyethylene), PVC (polyvinyl chloride), and PET (polyethylene terephthalate). The digestion time was 1 hour, and the total operation time was 2 hours. In contrast, in Comparative Example 2, using the existing method, the number of microplastics counted was only 10, and the types of microplastics that could be identified were only PP and PE. The digestion time was 2 hours, and the total operation time was 4 hours.

[0123] Figure 5 This diagram illustrates the types of microplastic particles detected in a urine sample according to an embodiment of the present invention. This is because the device of the present invention uses PMP material, avoiding interference from microplastics introduced by the sampling vessel and ensuring the accuracy of the detection results. The accompanying digestion method is gentle and efficient, removing matrix interference in a short time without damaging the structure of the microplastics. The two-step method of enrichment using a large-diameter filter membrane and refined enrichment using a small-diameter filter membrane effectively enriches microplastics of different particle sizes, improving the comprehensiveness of qualitative detection. In contrast, existing methods use polyethylene urine collection cups that introduce microplastic interference, and the digestion reagents are highly corrosive, potentially damaging some of the microplastic structure. Furthermore, the operation steps are complex and time-consuming, resulting in lower accuracy and comprehensiveness of the detection results.

[0124] Application Example 3: Detection of Microplastics in Urine of Different Populations

[0125] Using the device and method of this invention, people of different genders, ages, and occupations were selected as subjects. Morning urine was collected for qualitative and quantitative detection of microplastics. The specific detection results are shown in Table 3 below.

[0126] Table 3

[0127]

[0128] As shown in Table 3, the device and method of the present invention are applicable to the detection of microplastics in urine of different populations. They can accurately count the number of microplastics and determine their types, providing reliable data support for conducting microplastic exposure studies in different populations.

[0129] This invention relates to a device for collecting and pretreatment microplastics in urine, integrating collection, digestion, enrichment, and detection functions. It boasts advantages such as ease of operation, accurate detection, low cost, and wide applicability. This device can be widely applied in environmental monitoring, public health, and clinical medicine to conduct research on microplastic detection in urine from different populations and under different environments, providing reliable technical support for assessing the impact of microplastics on human health, and has broad application prospects. Simultaneously, the device and method of this invention can also provide a reference for the detection of microplastics in other biological samples (such as blood and feces), exhibiting broad application potential.

[0130] Through the above description of the embodiments, those skilled in the art can clearly understand that the above embodiments can be implemented by software, or by using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions of the above embodiments can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, mobile hard drive, etc.), including several instructions to cause a computer device (such as a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for collecting and pre-treating microplastics in urine, characterized in that, The system includes a urine collection funnel (1), a urine collector (2), a large-diameter filter membrane base (3), a small-diameter filter membrane base (4), a waste liquid bottle (5), a vacuum pump (6), and a stainless steel buckle (7). The urine collection funnel (1) is detachably and fixedly connected to the second port (201) of the urine collector (2) via the stainless steel buckle (7). The large-diameter filter membrane base (3) is detachably and fixedly connected to the first port (202) of the urine collector (2) away from the urine collection funnel (1) via the stainless steel buckle (7). A stainless steel filter membrane (301) can be placed inside the large-diameter filter membrane base (3), and a waste liquid outlet (302) is provided on the large-diameter filter membrane base (3). The small-diameter filter membrane base (4) can... The port (201) of the urine collector (2) is detachably and fixedly connected to the urine collector (2) by a stainless steel buckle (7). An alumina filter membrane (401) can be placed in the small-diameter filter membrane base (4). A waste liquid outlet (402) is provided on the small-diameter filter membrane base (4). An inlet (501) and a outlet (502) are provided on the waste liquid bottle (5). The waste liquid outlet (302) and the waste liquid outlet (402) can be connected to the inlet (501) to receive waste liquid from the large-diameter filter membrane base (3) or the small-diameter filter membrane base (4). The vacuum pump (6) is connected to the waste liquid bottle (5) to provide negative pressure filtration power so that urine or microplastic suspension can pass through the filter membrane quickly to achieve microplastic enrichment.

2. The apparatus for collecting and pre-treating microplastics in urine according to claim 1, characterized in that, The urine collection nozzle (1) and the urine collector (2) are both made of poly(4-methyl-1-pentene) (PMP). The urine collection nozzle (1) has an flared structure. The urine collector (2) has a transparent structure and is equipped with precise graduations on its bottle.

3. The apparatus for collecting and pre-treating microplastics in urine according to claim 1, characterized in that, The stainless steel filter membrane (301) has a pore size of 1.0 μm; the stainless steel filter membrane (301), the large-diameter filter membrane base (3), the small-diameter filter membrane base (4), and the stainless steel buckle (7) are all made of stainless steel.

4. The apparatus for collecting and pre-treating microplastics in urine according to claim 1, characterized in that, The urine collector (2) has a "V" shaped structure, with a first port (202) at the end near the urine collection funnel (1). The diameter of the first port (202) is larger than the diameter of the second port (201) at the end away from the urine collection funnel (1).

5. The apparatus for collecting and pre-treating microplastics in urine according to claim 1, characterized in that, The waste liquid bottle (5) is also provided with an exhaust port, and the vacuum pump (6) is connected to the exhaust port through a pipe; the drain port (502) is provided with a liquid control valve.

6. A method for collecting and pre-treating microplastics in urine using the device described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Sampling preparation: Connect the urine collection funnel (1) and the port (201) of the urine collector (2) with stainless steel buckles (7); place a stainless steel filter membrane (301) on the large-diameter filter membrane base (3), and fix the end of the large-diameter filter membrane base (3) away from the urine collection funnel (1) with stainless steel buckles (7) to seal it, and close the waste liquid outlet (302). S2, Urine collection: The subjects used the device assembled in step S1 to collect urine directly and recorded the urine volume through the scale on the urine collector (2) bottle. S3. Urine digestion: Open the stainless steel buckle (7) at the connection between the urine collection flare (1) and the urine collector (2), and remove the urine collection flare (1); add reagent 1 to the urine collector (2), wherein the reagent 1 is 30% hydrogen peroxide, and the volume ratio of the added reagent to the urine volume is 1:1, mix well and let stand for 30 minutes; then add reagent 2 to the urine collector (2), wherein the reagent 2 is potassium hydroxide, and the amount added is such that the mass fraction of potassium hydroxide in the digestion solution is 5%, mix well and let stand for 30 minutes to complete the urine digestion; the total time for the urine digestion is 1 hour; S4. Microplastic enrichment: Connect the waste liquid outlet (302) on the large-diameter filter membrane base (3) to the liquid inlet (501) of the waste liquid bottle (5), turn on the vacuum pump (6), and under negative pressure, the digested urine is filtered through the stainless steel filter membrane (301), and microplastics are enriched on the stainless steel filter membrane (301).

7. The method according to claim 6, characterized in that, The method further includes: S5. Quantitative detection of microplastics: Remove the stainless steel filter membrane (301), observe the appearance and morphology of microplastics under a microscope or electron microscope, and count the number.

8. The method according to claim 7, characterized in that, In step S5, the microscope is an optical microscope with a magnification of 100-400 times; the electron microscope is a scanning electron microscope.

9. The method according to claim 8, characterized in that, The method further includes: S6. Qualitative detection of microplastics: Cover the port (201) of the urine collector (2) with an alumina filter membrane (401), and fix the small-diameter filter membrane base (4) to the port (201) of the urine collector (2) with a stainless steel buckle (7) to seal it; invert the entire device so that the small-diameter filter membrane base (4) is at the bottom and the large-diameter filter membrane base (3) is at the top; open the stainless steel buckle (7) at the connection between the large-diameter filter membrane base (3) and the urine collector (2), and remove the large-diameter filter membrane base (3); slightly bend the stainless steel filter membrane (301) and place it in the urine collector. In the chamber of apparatus (2), add ultrapure water to rinse the stainless steel filter membrane (301) and rinse the microplastics on the filter membrane into the chamber. Then remove the stainless steel filter membrane (301). Connect the waste liquid outlet (402) on the bottom support (4) of the small diameter filter membrane to the liquid inlet (501) of the waste liquid bottle (5). Turn on the vacuum pump (6). Under negative pressure, the microplastic suspension is filtered through the alumina filter membrane (401), and the microplastics are enriched on the alumina filter membrane (401). Take out the alumina filter membrane (401) and dry it. Under micro-infrared spectroscopy or micro-Raman spectroscopy, the type of microplastics is determined by characteristic spectrum.

10. The method according to claim 9, characterized in that, In step S6, the amount of ultrapure water added is 2-3 times the volume of urine; the pore size of the alumina filter membrane (401) is 0.22-0.45 μm.

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