Food detection sample surface detection liquid extraction device and extraction method

Abstract

The application discloses a food detection sample surface detection liquid extraction device and method, which comprises a screen pipe, a top rod, a mounting ring plate, a positioning rod and a supporting rod. The side wall of the screen pipe is uniformly distributed with filtrate holes in the axial and circumferential directions, one end of the screen pipe is fixed with the top rod, the outer side of the screen pipe is detachably sleeved with the mounting ring plate, and the bottom of the ring plate is provided with the positioning rod and the supporting rod. The filtrate holes can form a uniform liquid environment, avoid extraction dead angles, and improve efficiency and detection accuracy; the top rod is convenient for handheld or docking with automatic equipment. The mounting ring plate and the screen pipe are detachable, which is convenient for cleaning and replacement to prolong the service life; the combination of the positioning rod and the supporting rod can stably clamp the sample, prevent the sample from falling off and shifting due to liquid impact, and guarantee the stability and consistency of extraction. The maximum contact area of the vortex winding long strip sample is maximized, the sample is prevented from being damaged by layer-by-layer winding, the positioning rod clamping groove realizes rapid fixing, and the screen pipe, a centrifugal tube cooperates to form a closed extraction environment, reduces pollution, improves reliability and repeatability, and is suitable for automatic operation to improve detection throughput.

Description

Technical Field

[0001] This invention belongs to the field of sample pretreatment technology for automated food safety testing equipment, and in particular relates to a device and method for extracting surface detection liquid from food testing samples. Background Technology

[0002] As consumers' demands for food quality increase and food safety incidents become more frequent, the public's awareness of food safety is rising, and the monitoring of food quality and safety is receiving more and more attention.

[0003] Enzyme-linked immunosorbent assay (ELISA) is widely used in the detection of bacteria and toxins, fungi and toxins, viruses and parasites, proteins, hormones, other physiologically active substances, drug residues, and antibiotics. The method itself is simple, rapid, and efficient, making it widely applicable in the field of food safety testing. Meanwhile, the existing manual operation mode of food safety testing, due to its low efficiency and the influence of human factors on errors, can no longer meet the rapidly growing market demand. Therefore, the development and application of high-throughput, rapid, automated food safety testing equipment has become an objective necessity in the field of food safety testing.

[0004] In the determination of pesticide residues, the matrix effect has a significant impact on the detection results. The optimal way to eliminate the matrix effect is to reduce or eliminate the source of the matrix in the sample. Taking fruits and vegetables as an example, the more shearing wounds there are, the more pigments (such as chlorophyll, carotenoids, etc.), lipids, proteins, polysaccharides, organic acids, and other substances are released, and the more pronounced the matrix effect generally becomes. Although some relatively successful purification methods have been developed to reduce the interference of the matrix effect on the detection results, they cannot achieve ideal purification effects for all precipitates. Furthermore, when the precipitate has a similar structure to the analyte, it reduces the recovery rate of the analyte in the extract, directly affecting the detection accuracy. Therefore, reducing shearing wounds, especially for the rapid detection of contact pesticides, is undoubtedly a necessary step. However, for rapid testing of fruits and vegetables, when the cut opening is reduced, it often means that the individual samples being tested are generally larger. This can lead to physical support issues, as mentioned earlier, causing the testing equipment to malfunction. Furthermore, the samples within the confined space of a centrifuge tube can easily overlap, affecting the effective washing of the samples by the extraction solution. For example, when testing leeks, if the whole leek is placed in a centrifuge tube for analyte extraction, the cut opening is only the severed portion, resulting in minimal organic matter precipitation and thus minimal matrix effect on the detection. However, within the confined space of a centrifuge tube, the samples themselves are prone to coiling, which can prevent the extraction solution from effectively washing the samples, leading to insufficient analyte extraction.

[0005] Therefore, we need to design a device and method for extracting the surface test liquid of food test samples to solve these problems. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a device and method for extracting detection liquid from the surface of food test samples.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A sample surface detection liquid extraction device for food testing includes a centrifuge tube with a cap and an extraction hole. A sieve tube is disposed inside the centrifuge tube, with one end closed and the other end open. When a suction tube is inserted through the extraction hole, the tip of the suction tube is projected into the top opening of the sieve tube. A plurality of filtration holes are provided through the side wall of the sieve tube, and the plurality of filtration holes are evenly arranged along the axial and circumferential directions of the sieve tube.

[0008] This setup ensures that the dimensions of the mounting ring plate, sieve tube, and centrifuge tube are precisely matched, guaranteeing that the entire device can be stably placed inside the centrifuge tube. At the same time, the standardization ensures that the aspirator can be inserted from its open end regardless of the angle of the sieve tube, eliminating the need to purchase additional specialized instruments, reducing experimental costs and simplifying operation.

[0009] Preferably, a limiting plate is fixedly provided at the open end of the sieve tube, and an installation ring plate is detachably fitted on the outside of the sieve tube. The outer diameter of the installation ring plate does not exceed the inner diameter of the centrifuge tube. A number of positioning rods and a number of support rods are provided at the bottom of the installation ring plate. The installation ring plate is provided with positioning holes, and the number of positioning holes is at least two. Each positioning hole is provided with a positioning rod, and the free end of each positioning rod is provided with a slot.

[0010] This design, with the cooperation of the limiting plate and mounting ring plate, supports the sieve tube, keeping it vertical within the centrifuge tube. The design of at least two positioning rods and end slots reliably secures the start and end of the sample, preventing loosening during winding or extraction. The shape and size of the slots precisely match the sample ends, reducing positional deviations caused by sliding and thus avoiding uneven extraction. Furthermore, the slot structure facilitates quick sample loading and unloading, shortening operation time and improving work efficiency, making it particularly suitable for batch testing scenarios. The arrangement of support holes and support rods provides multi-point support for the sample, keeping it spread out in the extraction solution and effectively increasing the contact area. The uniform distribution of multiple support points prevents localized stacking or compression of the sample, ensuring that the extraction solution can evenly penetrate every part of the sample surface. This design also reduces mechanical damage to the sample during processing, maintaining its original state and contributing to the accuracy of subsequent testing.

[0011] Preferably, the plurality of support rods are arranged in a circle on the mounting ring plate. When two positioning rods and the plurality of support rods together form a circle around the center of the ring plate, the positions of the two positioning rods are adjacent. When the plurality of support rods form more than one circle around the center of the ring plate, one of the positioning rods is located on the innermost ring, and the other positioning rod is located on the outermost ring.

[0012] This design, with its circular arrangement of support rods, allows the sample to be wound evenly in a spiral, significantly increasing the contact area with the extraction liquid and improving extraction efficiency. The positioning of the positioning rods facilitates both initial and final fixation of the sample, while maintaining uniform tension during winding, preventing breakage or deformation due to excessive localized stress. This layout also allows for easy control of the sample winding density, adapting to different detection needs.

[0013] Preferably, a top rod is fixedly provided on the outer side of the closed end of the sieve tube. The top rod is coaxial with the sieve tube, and the sum of the lengths of the sieve tube and the top rod does not exceed the depth of the centrifuge tube.

[0014] This design supports the sieve tube, preventing it from sinking too deep and causing the support rod on the mounting ring to collide with the bottom of the centrifuge tube. Supporting the sieve tube also allows for a larger space underneath it, facilitating sample cleaning.

[0015] Preferably, a locking block is fixedly provided on the inner side of the mounting ring plate. When the mounting ring plate is combined with the sieve tube, the free end of the locking block is inserted into the filtrate hole on the sieve tube.

[0016] This design, with the locking block inside the mounting ring plate engaging with the filtrate hole of the sieve tube, achieves rapid positioning and a secure connection, ensuring no relative displacement occurs during centrifugation or cleaning. This connection method is simple in structure, easy to operate, and facilitates disassembly and cleaning, maintaining the cleanliness of the device and reducing the risk of cross-contamination. The tight fit between the locking block and the filtrate hole also reduces leakage of the extract at the connection point, improving operational safety.

[0017] Preferably, the diameter of the positioning rod is twice the diameter of the support rod, and each positioning rod is threadedly connected to the positioning hole, and each support rod is threadedly connected to the support hole.

[0018] This design, with the positioning rod having a larger diameter than the support rod, enhances the structural strength and stability of the sample fixing end, ensuring that it will not bend or break during winding and extraction. The threaded connection allows for adjustment of the height of both the positioning and support rods as needed, and facilitates the replacement of rods of different sizes or materials to accommodate different types and sizes of samples. This adjustability greatly improves the versatility and flexibility of the device, expanding its application range.

[0019] Preferably, when the number of circles formed by the plurality of support rods exceeds one, the lengths of the support rods and the positioning rods are shortened circle by circle from the innermost circle to the outermost circle.

[0020] This design, with the support and positioning rods decreasing in length from the inside out, creates a conical structure when the sample is wrapped. This structure facilitates the flow of the extract between different layers, preventing liquid stagnation between sample layers and thus improving extraction efficiency and uniformity. The conical structure also reduces mutual compression of the samples during the wrapping process, maintaining appropriate gaps between samples, which is beneficial for sufficient contact and penetration of the extract.

[0021] The extraction method based on the above-mentioned food testing sample surface detection liquid extraction device includes the following steps: S1. Cut the long strip-shaped food test sample into pieces, with the cut length not less than the circumference of the mounting ring plate; S2. Insert one end of the long strip food test sample into the slot at the end of the positioning rod on the innermost circle, and then wrap it around the circle formed by the support rods. When there is more than one circle formed by the support rods, wrap it layer by layer from the innermost circle in the form of a spiral line. Finally, insert the last end of the long strip food test sample into the slot at the free end of the positioning rod on the outermost circle. S3. Install the food sample extraction device with the long strip wrapped around it onto the sieve tube by cooperating with the locking block on the mounting ring plate and the filter hole on the sieve tube. Then insert the sieve tube into the centrifuge tube containing the surface extraction liquid, and then cover the tube cap to seal the opening of the centrifuge tube. Then clean the surface of the long strip of food sample to obtain the sample extraction liquid for extracting the long strip of food sample.

[0022] The advantages and positive effects of this invention are: 1. The present invention features a filtration hole design with evenly distributed pores on the sidewall of the sieve tube, enabling the extract to form a uniformly flowing liquid environment on the sample surface, avoiding local concentration differences or extraction dead zones, thereby improving extraction efficiency and the accuracy of detection results. The top rod design facilitates both handheld operation and integration with automated equipment, enhancing operational convenience. The detachable connection between the mounting ring plate and the sieve tube allows for individual cleaning and replacement of each component, extending its service life; the combination structure of the positioning rod and support rod stably clamps the sample, preventing it from falling off or shifting due to liquid impact during centrifugation or washing, ensuring the stability and consistency of the extraction process.

[0023] 2. The extraction device of this invention maximizes the contact area between the sample and the extraction liquid by winding the long strip sample in a vortex manner, thereby improving extraction efficiency. The layer-by-layer winding method ensures uniform force on the sample, avoiding sample damage caused by excessive local tension. The positioning rod slot design enables rapid and reliable sample fixation, simplifying the operation process. Its use in conjunction with sieve tubes and centrifuge tubes allows the entire extraction process to be carried out in a closed environment, reducing the risk of external contamination and improving the reliability and repeatability of the test results. Furthermore, this method is suitable for automated operation, which is beneficial for improving detection throughput and efficiency. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the state of the sieve tube in the centrifuge tube when the limiting plate is not installed and the ring plate is installed, as well as the state when it is in conjunction with the suction tube. Figure 2 This is a schematic diagram of the extraction device and sieve tube assembly structure of the present invention; Figure 3 This is a schematic diagram of the positioning rod and support rod structure of the present invention; Figure 4 This is a schematic diagram of the mounting ring plate and locking block structure of the present invention; Figure 5 This is a top view schematic diagram of the multi-ring support rod distribution structure of the present invention; Figure 6 This is a schematic diagram showing the state of the sieve tube after the installation of the limiting plate and the installation ring plate, inside the centrifuge tube, and in conjunction with the suction tube.

[0026] The annotations in the attached figures are explained as follows: 1. Sieve tube; 2. Limiting plate; 3. Top rod; 4. Filtration hole; 5. Mounting ring plate; 6. Positioning hole; 7. Support hole; 8. Positioning rod; 9. Slot; 10. Support rod; 11. Locking block; 12. Centrifuge tube; 13. Tube cap; 14. Extraction hole; 15. Suction tube. Detailed Implementation

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, 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, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] 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 will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] The present invention will be further described below with reference to the accompanying drawings: Example 1: As Figure 1 As shown, a sample surface detection liquid extraction device for food testing includes a centrifuge tube 12, a cap 13 on the centrifuge tube 12, an extraction hole 14 on the cap, and a sieve tube 1 inside the centrifuge tube 12. The sieve tube 1 separates the sample from the extraction liquid. One end of the sieve tube 1 is closed, and the other end is open. When a suction tube 15 is inserted through the extraction hole 14, the tip of the suction tube 15 is projected into the opening at the top of the sieve tube 1. In this embodiment, the length of the sieve tube 1 is not less than half the depth of the centrifuge tube 12, and the inner diameter of the open end of the sieve tube 1 does not exceed one-third of the inner diameter of the extraction hole 14, and is not less than half the inner diameter of the extraction hole 14. Figure 1The dimensional constraints ensure that once the sieve tube 1 is placed into the centrifuge tube 12 with its open end facing upwards, the suction tube 15 can be inserted into the sieve tube 1 regardless of its angle after being inserted through the extraction hole 14. Several filtration holes 4 are evenly distributed along the axial and circumferential directions of the sieve tube 1, allowing the extract to circulate evenly within the device and contact the sample surface. This ensures that all areas of the sample can fully interact with the extract, solving the problem of insufficient local extraction. A top rod 3 is fixedly installed on the outside of the closed end of the sieve tube 1. The top rod 3 is coaxial with the sieve tube 1, and the sum of the lengths of the sieve tube 1 and the top rod 3 does not exceed the depth of the centrifuge tube 12. The top rod 3 fixedly installed at one end of the sieve tube 1 avoids simply supporting the sieve tube, preventing it from sinking too deeply and causing the support rod 10 on the mounting ring 5 to collide with the bottom of the centrifuge tube 12. Supporting the sieve tube 1 also allows for a larger space below it, facilitating sample cleaning. It should be noted that after the sample is extracted by the suction tube 15, the level of the washing solution needs to be above the top rod 3.

[0030] The working process of this embodiment: First, this application is based on the principles of extraction kinetics and fluid mechanics. During oscillation, the sieve tube 1 inside the centrifuge tube 12 can disrupt the laminar flow state of the washing liquid, forming eddies and shear forces, which can enhance the friction between the washing liquid and the test sample, accelerate the desorption and dissolution of pesticides and other target substances, and improve the solid-liquid mass transfer efficiency.

[0031] To use, first place the sample to be cleaned at the bottom of the centrifuge tube, then insert the sieve tube, add washing solution to the centrifuge tube, then cap the centrifuge tube, and then shake the centrifuge tube to allow the washing solution to clean the sample surface. During cleaning, the vibration effect of the sieve tube creates a vortex in the washing liquid inside the centrifuge tube after shaking. Since the sieve tube is not fixed inside the centrifuge tube, it shakes synchronously inside the centrifuge tube when the centrifuge tube is shaken. The shaking sieve tube breaks the vortex formed by the washing liquid into micro-vortices, thereby increasing the liquid-solid contact area and friction time. It also makes the washing liquid contact the sample more evenly, accelerates the dissolution of substances on the surface of the sample to be tested, and improves the cleaning efficiency.

[0032] Example 2: Figures 2-6 As shown, when the ring plate 5 is not installed on the sieve tube 1, the extraction of the extract can be carried out by simply putting the long strip-shaped food sample to be extracted directly into the centrifuge tube 12, adding washing solution into the centrifuge tube 12, and then putting the sieve tube 1 into the centrifuge tube 12 with the open end facing upward. Then, the tube cap 13 is put on the open end of the centrifuge tube 12, and then the centrifuge tube 12 is shaken to clean the surface of the long strip-shaped food sample with washing solution.

[0033] Because the diameter of the open end of the sieve tube 1 is greater than 1 / 3 but less than 1 / 2 of the diameter of the centrifuge tube 12, this ensures sufficient space between the sieve tube 1 and the centrifuge tube 12 to hold elongated food samples. During the washing process, the sieve tube 1 also vibrates and shakes with the centrifuge tube 12 due to this space, thus impacting the elongated food samples and improving the washing effect. Simultaneously, it ensures that the open end of the sieve tube 1 aligns with the extraction hole 14 on the cap 13. After washing, the suction tube 15 is inserted into the centrifuge tube 12 through the extraction hole 14 on the cap 13. Figure 1 As shown, the head of the suction tube 15 that enters the centrifuge tube 12 can enter the sieve tube 1 to extract the sample extract of the long strip-shaped food test sample.

[0034] A mounting ring plate 5 is detachably fitted on the outside of the sieve tube 1, providing a mounting carrier for the positioning rod 8 and the support rod 10, so that the sample fixing structure and the sieve tube 1 form a modular combination. The positioning rod 8 is used to fix the end of the sample, and the support rod 10 is used to support the sample in the winding state. The two work together to achieve stable arrangement of the sample. The mounting ring plate 5 has positioning holes 6 to provide installation positions for the positioning rod 8, and the opening position of the positioning hole 6 matches the arrangement trajectory of the support rod 10. There are at least two positioning holes 6 to adapt to the fixing requirements at both ends of the sample, ensuring that the beginning and end of the sample can be fixed after winding. Each positioning hole 6 is provided with a positioning rod 8, and each positioning rod 8 has a slot 9 at its free end. The opening size of the slot 9 is adapted to the thickness of common long strip food samples. The sample is fixed by engaging with the end of the sample through the slot 9, preventing the sample from slipping during winding. The mounting ring plate 5 is also provided with several support holes 7. The number and arrangement density of the support holes 7 are set according to the number of turns and spacing of the sample winding, providing installation positions for the support rods 10. Each support hole 7 is provided with a support rod 10. The top height of the support rods 10 is consistent, and they cooperate with the positioning rods 8 to form a support structure for sample winding, so that the sample can maintain a regular shape after winding and avoid local sagging or stacking. Several support rods 10 are arranged in a circle on the mounting ring plate 5. The diameter of the circular trajectory is determined according to the sample width and the inner diameter of the centrifuge tube 12, providing a circular trajectory for sample winding. When two positioning rods 8 and several support rods 10 together form a circle around the center of the ring plate, the positions of the two positioning rods 8 are adjacent, and the distance between them is no greater than the end distance after a single turn of sample winding, which is suitable for the close-range fixation requirements of the two ends of the sample during single-turn winding. When the number of circles formed by several support rods 10 around the center of the ring plate exceeds one, the spacing between each circle is uniform. One positioning rod 8 is located on the innermost ring, and the other positioning rod 8 is located on the outermost ring. The line connecting the two positioning rods 8 passes through the center of the ring plate, which is suitable for the long-range fixation requirements of the starting and ending ends of the sample during multi-turn spiral winding.

[0035] A locking block 11 is fixedly installed on the inner side of the mounting ring plate 5. There are at least two locking blocks 11, which are evenly distributed along the inner wall of the mounting ring plate 5. When the mounting ring plate 5 is combined with the sieve tube 1, the free end of the locking block 11 is inserted into the filtrate hole 4 on the sieve tube 1. The size of the locking block 11 is precisely matched with the pore diameter of the filtrate hole 4. The locking block 11 and the filtrate hole 4 cooperate to achieve rapid positioning and fixation of the mounting ring plate 5 and the sieve tube 1, ensuring that there is no relative displacement between the two during centrifugation, shaking and other operations, and avoiding sample position displacement that affects the extraction effect.

[0036] The diameter of the positioning rod 8 is twice that of the support rod 10. Because the positioning rod 8 needs to withstand the tension and fixing force generated when the sample is wrapped, the larger diameter can improve the structural strength and prevent the positioning rod 8 from bending and deforming. Each positioning rod 8 is connected to the positioning hole 6 by a threaded engagement, and each support rod 10 is connected to the support hole 7 by a threaded engagement. The thread pitch is consistent, so that the extension length of the positioning rod 8 and the support rod 10 can be adjusted according to the thickness of the sample and the number of wrapping layers. It is also convenient to disassemble and clean or replace the damaged rods separately.

[0037] The inner diameter of the mounting ring plate 5 is the same as the outer diameter of the sieve tube 1. A transition fit is adopted to ensure a tight fit between the mounting ring plate 5 and the sieve tube 1 after assembly, with no obvious gap. The outer diameter of the mounting ring plate 5 is the same as the inner diameter of the centrifuge tube 12. A transition fit is also adopted to ensure that the mounting ring plate 5 can be stably inserted into the centrifuge tube 12, thereby achieving the positioning of the entire device in the centrifuge tube 12 and preventing the device from shaking inside the centrifuge tube 12.

[0038] When the number of circles formed by the support rods 10 exceeds one, the lengths of the support rods 10 and the positioning rods 8 decrease from the innermost circle to the outermost circle. The difference in the shortened length is determined according to the interlayer spacing after the sample is wrapped, so that the wrapped sample forms a tapered structure that gradually shrinks from the inside to the outside. This provides a smooth channel for the flow of the extract between samples in different layers, avoids liquid stagnation between sample layers, and ensures that the sample in each layer can fully contact the extract.

[0039] The extraction method using the above-mentioned food testing sample surface detection liquid extraction device includes the following steps: When using it, check the condition of components such as the filtrate hole 4 of the sieve tube 1 and the top rod 3. According to the length and thickness of the long strip food sample, adjust the extension length of the positioning rod 8 and the support rod 10 on the mounting ring plate 5 through the threaded connection. Then cut the long strip food test sample. It should be noted that the minimum cutting length should not be less than the circumference of the mounting ring plate 5. Then, insert one end of the long strip food test sample into the slot 9 at the end of the positioning rod 8 on the innermost circle, and then wrap it around the circle formed by the support rods 10. When there is more than one circle formed by the support rods 10, wrap it layer by layer from the innermost circle in the form of a spiral line. Finally, insert the last end of the long strip food test sample into the slot 9 at the free end of the positioning rod 8 on the outermost circle. Finally, the long strip-shaped food sample extraction device is installed onto the sieve tube 1 by engaging the locking block 11 on the mounting ring plate 5 with the filter hole 4 on the sieve tube 1. Then, the sieve tube 1 is inserted into the centrifuge tube 12 containing the surface extraction solution. After insertion, the limiting plate 2 on the sieve tube 1 engages with the centrifuge tube 12 to support it and prevent shaking. The opening of the centrifuge tube 12 is then closed, and the surface of the long strip-shaped food sample is washed. The extraction solution flows through the evenly distributed filter holes 4 of the sieve tube 1, fully contacting all areas of the sample and ensuring that the surface substances are fully dissolved in the washing solution. Finally, the suction tube is inserted into the sieve tube through the extraction hole 14 on the tube cap to extract the washing solution, obtaining the sample extract from the long strip-shaped food sample. Then, the tube cap 13 of the centrifuge tube 12 is opened, the assembly is removed, and the sieve tube 1 is separated from the mounting ring plate 5. After unscrewing the positioning rod 8 and the support rod 10, each component is cleaned separately for future use.

[0040] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A sample surface detection liquid extraction device for food testing, characterized in that: The centrifuge tube (12) is provided with a cap (13) and an extraction hole (14) on the cap. A sieve tube (1) is provided inside the centrifuge tube (12). One end of the sieve tube (1) is closed and the other end is open. When the suction tube (15) is inserted through the extraction hole (14), the tip of the suction tube (15) is projected into the top opening of the sieve tube (1). A plurality of filtration holes (4) are provided through the side wall of the sieve tube (1). The plurality of filtration holes (4) are evenly arranged along the axial and circumferential directions of the sieve tube (1).

2. The sample surface detection liquid extraction device for food testing according to claim 1, characterized in that: A limiting plate (2) is fixedly installed at the open end of the sieve tube (1). An installation ring plate (5) is detachably fitted on the outside of the sieve tube (1). The outer diameter of the installation ring plate (5) does not exceed the inner diameter of the centrifuge tube (12). Several positioning rods (8) and several support rods (10) are provided at the bottom of the installation ring plate (5). A positioning hole (6) is opened on the installation ring plate (5). There are at least two positioning holes (6). A positioning rod (8) is provided in each positioning hole (6), and a slot (9) is opened at the free end of each positioning rod (8).

3. The sample surface detection liquid extraction device for food testing according to claim 2, characterized in that: The mounting ring plate (5) is also provided with a number of support holes (7), and each support hole (7) is provided with a support rod (10). The support rods (10) are arranged in a circle on the mounting ring plate (5). When two positioning rods (8) and the support rods (10) together form a circle around the center of the ring plate, the positions of the two positioning rods (8) are adjacent. When the number of circles formed by the support rods (10) around the center of the ring plate exceeds one, one of the positioning rods (8) is located on the innermost ring, and the other positioning rod (8) is located on the outermost ring.

4. The sample surface detection liquid extraction device for food testing according to claim 1, characterized in that: A top rod (3) is fixedly installed on the outside of the closed end of the sieve tube (1). The top rod (3) is coaxial with the sieve tube (1), and the sum of the lengths of the sieve tube (1) and the top rod (3) does not exceed the depth of the centrifuge tube (12).

5. The sample surface detection liquid extraction device for food testing according to claim 2, characterized in that: A locking block (11) is fixedly provided on the inner side of the mounting ring plate (5). When the mounting ring plate (5) is combined with the sieve tube (1), the free end of the locking block (11) is inserted into the filtrate hole (4) on the sieve tube (1).

6. The sample surface detection liquid extraction device for food testing according to claim 3, characterized in that: The diameter of the positioning rod (8) is twice the diameter of the support rod (10), and each positioning rod (8) is connected to the positioning hole (6) by a threaded engagement, and each support rod (10) is connected to the support hole (7) by a threaded engagement.

7. The sample surface detection liquid extraction device for food testing according to claim 2, characterized in that: When the number of circles formed by the support rods (10) exceeds one, the lengths of the support rods (10) and the positioning rods (8) are shortened from the innermost circle to the outermost circle.

8. An extraction method based on the sample surface detection liquid extraction device for food testing according to any one of claims 2 to 7, characterized in that, Includes the following steps: S1. Cut the long strip-shaped food test sample into pieces, and the cut length shall not be less than the circumference of the mounting ring plate (5); S2. Insert one end of the long strip food test sample into the slot (9) at the end of the positioning rod (8) on the innermost circle, and then wrap it around the circle formed by the support rods (10). When there is more than one circle formed by the support rods (10), wrap it layer by layer from the innermost circle in the form of a spiral line. Finally, insert the last end of the long strip food test sample into the slot (9) at the free end of the positioning rod (8) on the outermost circle. S3. By using the locking block (11) on the mounting ring plate (5) and the filter hole (4) on the sieve tube (1) to install the food test sample extraction device wrapped with a long strip onto the sieve tube (1), then insert the sieve tube (1) into the centrifuge tube (12) containing the surface extraction liquid, and then seal and cover the tube cap (13) to clean the surface of the long strip of food test sample. S4. Insert the suction tube (15) into the sieve tube (1) through the extraction hole (14) on the tube cap (13) to extract the washing liquid and obtain the sample extract for extracting the long strip-shaped food test sample.

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