Solid-phase extraction device for detecting mycotoxin in food

Abstract

The invention belongs to the technical field of solid-phase extraction, particularly relates to a solid-phase extraction device for detecting mycotoxin in food, and provides the following scheme aiming at the problem that an existing device cannot provide targeted extraction and purification measures according to different physicochemical properties of aflatoxin and ochratoxin A. Comprising an extraction tank, an upper circulation tank, an extraction tank and a lower circulation tank which are communicated from top to bottom and form a circulation system through extraction circulation pipelines. The mycotoxin extraction device has two switchable working modes of separate extraction of mycotoxin and co-extraction of mycotoxin. In the independent extraction mode, two sets of independent circulation paths can use extracting solutions optimized for different toxins and exclusive purification columns in parallel; in the co-extraction mode, different extracting solutions can flow through the same composite purification column in sequence. The negative pressure suction valve assembly controlled by negative pressure can automatically supplement liquid when the extraction liquid level is too low, and titration type efficient extraction is achieved.

Description

Technical Field

[0001] This invention relates to a solid-phase extraction device, specifically a solid-phase extraction device for detecting mycotoxins in food, and belongs to the field of solid-phase extraction technology. Background Technology

[0002] In the field of food safety testing, especially for monitoring mycotoxins in agricultural products such as kernels and grains, efficient and accurate sample pretreatment technology is a key bottleneck to ensure the reliability of test results. The simultaneous detection of aflatoxins (AFs) and ochratoxin A (OTA), two highly carcinogenic mycotoxins with vastly different physicochemical properties, presents a significant challenge to pretreatment technology.

[0003] Currently, technological development for the simultaneous purification of multiple toxins mainly focuses on the development of novel adsorbent materials, aiming to capture multiple toxins simultaneously using a single purification column. For example, in existing technologies, CN115608339A discloses a magnetic solid-phase extractant for the simultaneous enrichment and purification of nine fungal toxins. This technology utilizes a magnetic triazine-based covalent organic framework nanomaterial, employing vortexing, ultrasonication, and magnetic separation steps to achieve one-time adsorption and purification of multiple toxins, including AFB1 and OTA. Another example is CN107727781A, which discloses a solid-phase extraction column for the simultaneous purification of multiple fungal toxins and its application. This column uses a packing material composed of multi-walled carbon nanotubes and reversed-phase chromatography packing, aiming to achieve one-time purification. Although these material-based solutions represent an improvement in simplifying the process, they share a fundamental limitation: their design logic seeks a "universal" adsorbent or combination of adsorbents with sufficient adsorption capacity for multiple toxins, and implicitly uses an extract with a fixed composition. However, AFs (weakly acidic) and OTAs (neutral) differ significantly in their optimal extraction environments. Using a compromise single extraction system makes it difficult to simultaneously ensure the highest extraction efficiency for both, directly limiting the improvement of the overall sensitivity and recovery rate of the detection method. In other words, current technologies pursue "integration of purification processes" but sacrifice the "specificity of the extraction process," failing to systematically optimize the entire sample pretreatment workflow. On the other hand, traditional solid-phase extraction devices are limited in function, have low automation, are cumbersome and time-consuming to operate, and heavily rely on human experience, making it difficult to meet the growing demands of modern testing laboratories for high throughput, high reproducibility, and standardized operation. Although pretreatment systems aiming at automation have emerged in the market, their core focus is mostly on the automated operation of specific materials (such as immunomagnetic beads), lacking sufficient process flexibility. They also cannot solve the problem of simultaneous detection of multiple toxins. Summary of the Invention

[0004] This invention provides a solid-phase extraction device for detecting mycotoxins in food, addressing the problem that existing devices cannot provide targeted extraction and purification measures based on the different physicochemical properties of aflatoxin and ochratoxin A.

[0005] The present invention achieves the above objectives through the following technical solution: a solid phase extraction device for detecting mycotoxins in food, comprising multiple extraction mechanisms, wherein the extraction mechanism comprises an extraction tank, an upper circulation tank, an extraction tank and a lower circulation tank connected sequentially from top to bottom, an extraction circulation pipeline is provided between the extraction tank and the upper circulation tank, and an extraction circulation pipeline is provided between the upper circulation tank and the lower circulation tank. The upper and lower circulation tanks are arranged in opposite positions as two sets of circulation paths. When the two extraction tanks are connected to either circulation path, the fungal toxins are extracted individually. When the same extraction tank is connected to both circulation paths, the fungal toxins are extracted together. When one of the upper circulation tanks and the extraction tank are in circulation extraction state through the extraction circulation pipeline, the other upper circulation tank and its connected extraction tank and lower circulation tank are in circulation extraction state through the extraction circulation pipeline. The bottom of the upper circulation tank is connected to a circulation guide pipe, and a negative pressure suction valve assembly is installed inside the circulation guide pipe, which is initially in a closed state. The lower circulation tank is connected to a negative pressure suction pipe, and an extraction column is installed inside the extraction tank. When the extract in the extraction tank is drawn out through the negative pressure suction pipe to the point that it can no longer completely cover the extraction column, the negative pressure suction valve assembly is opened through the negative pressure suction of the negative pressure suction pipe.

[0006] As a further embodiment of the present invention: the device also includes an outer frame, in which an upper horizontal plate and a lower horizontal plate are fixedly connected in a horizontal manner, an extraction tank is fixedly connected to the top of the outer frame, the body of the upper circulation tank is fixedly connected to the upper horizontal plate in a through manner, the body of the lower circulation tank is fixedly connected to the lower horizontal plate in a through manner, and a vertically arranged vertical partition is also fixedly connected in a vertical manner inside the outer frame, the vertical partition being located between adjacent extraction mechanisms.

[0007] As a further embodiment of the present invention: a material-holding mesh basket is movably installed inside the extraction tank. The inner wall of the extraction tank is connected to several side wall support plates in a ring shape, which abut against the outer side of the material-holding mesh basket. The bottom surface of the extraction tank is connected to several bottom support plates in a ring shape, which support the bottom of the material-holding mesh basket. A liquid-guiding ring is fixedly connected to the inner wall of the extraction tank. The liquid-guiding ring is installed above the material-holding mesh basket installed inside the extraction tank. An annular cavity is opened inside the liquid-guiding ring. Several spray holes communicating with the annular cavity are opened on the inner side of the liquid-guiding ring. The spray holes are arranged vertically in groups of three, and the opening angle of each group of spray holes is inclined upward, horizontal and downward respectively from top to bottom. An inlet pipe communicating with the annular cavity is connected to the outer side of the liquid-guiding ring. A liquid level sensor is also fixedly connected to the inner wall of the extraction tank. The liquid level sensor is connected to an external terminal via a signal connection.

[0008] As a further embodiment of the present invention: the circulating liquid guide pipe connected to the bottom of the upper circulation tank is fitted with an upper connector assembly for sealing and docking with the extraction tank. The upper connector assembly includes an inner groove surface, a docking seat, a sealing gasket, and a second spring. The inner groove surface is formed on the outer wall of the circulating liquid guide pipe. The docking seat and the second spring are both movably fitted on the inner groove surface, and the second spring abuts against the lower part of the docking seat. The sealing gasket is fixedly connected to the inner side of the docking seat. The negative pressure suction valve assembly installed inside the circulating liquid guide pipe includes a beveled retaining ring, a bottom sealing plate, a connecting rod, an upper limit plate, and a first spring. The beveled retaining ring is fixedly connected to the inner wall of the circulating liquid guide pipe. The rod body movably passes through the beveled retaining ring. The upper end of the connecting rod is fixedly connected to the upper limit plate, and the lower end of the connecting rod is fixedly connected to the bottom sealing plate. The rod body is fitted with the first spring, and the first spring abuts between the beveled retaining ring and the upper limit plate.

[0009] As a further embodiment of the present invention: the upper end of the lower circulation tank is connected to a circulation inlet pipe, and a lower connector assembly for sealing and docking with the extraction tank is sleeved on the body of the circulation inlet pipe. The lower connector assembly has the same structure as the upper connector assembly, and the lower end of the lower circulation tank is connected to a circulation outlet pipe.

[0010] As a further aspect of the present invention: the inner wall of the extraction tank has an inner inclined surface, an extraction column is movably installed inside the extraction tank, and the shape of the extraction column matches the inner inclined surface of the extraction tank. A bottom support mesh is connected to the bottom of the extraction tank, and a tank cover is threadedly connected to the upper end of the extraction tank. An upper limit mesh is fixedly connected inside the tank cover. When the tank cover and the extraction tank are in a threaded connection state, the extraction column fits against the inner inclined surface of the extraction tank, and the extraction column is clamped between the bottom support mesh and the upper limit mesh. A tank body push plate is provided on the outer side of the extraction tank, and the tank body push plate has three tank body positioning holes arranged side by side. When in the state of separate extraction of fungal toxins, the two extraction tanks are respectively locked. The extraction columns are placed in the positioning holes on both sides of the tank body, and the extraction columns in the two extraction tanks are respectively aflatoxin extraction columns and ochratoxin extraction columns; when in the state of co-extraction of fungi and toxins, the extraction tanks are respectively locked in the positioning hole in the middle of the tank body, and the extraction columns in the extraction tanks are composite immunoaffinity extraction columns; the inner wall of the positioning hole of the tank body is embedded with a positioning rubber ring, and the outer wall of the extraction tank has a positioning concave surface. When the extraction tank is inserted into the positioning hole of the tank body, the positioning rubber ring is locked in the positioning concave surface; the inner walls on both sides of the frame body and the two sides of the vertical partition plate are fixedly connected with slide rail slots, and the two sides of the tank body push plate are movably locked in the slide rail slots.

[0011] As a further aspect of the present invention: when the fungal toxin is extracted separately, the caps of the two extraction tanks are connected by threads and are connected to a first liquid inlet pipe. The other ends of the two first liquid inlet pipes are connected to a circulating liquid guide pipe, and the first liquid inlet pipe and the circulating liquid guide pipe are sealed and connected by an upper connector assembly. The bottom ends of the two extraction tanks are connected to a first liquid outlet pipe, and the other ends of the two first liquid outlet pipes are connected to a circulating liquid inlet pipe, and the first liquid outlet pipe and the circulating liquid inlet pipe are sealed and connected by a lower connector assembly. When in the state of co-extraction of fungal toxins, the screw-connected lid of the extraction tank is connected to two second inlet pipes. The two second inlet pipes are connected to the can lid by inlet solenoid valves. The other end of the two second inlet pipes is connected to the circulating liquid guide pipe, and the second inlet pipes and the circulating liquid guide pipe are sealed together by an upper connector assembly. The bottom of the extraction tank is connected to two second outlet pipes. The two outlet pipes are connected to the extraction tank by outlet solenoid valves. The other end of the two outlet pipes is connected to the circulating liquid inlet pipe, and the second outlet pipes and the circulating liquid inlet pipe are sealed together by a lower connector assembly. Both the inlet solenoid valves and the outlet solenoid valves are electrically connected to an external terminal.

[0012] As a further embodiment of the present invention: the upper ends of the pipe walls of the two lower circulation tanks are connected to air guide pipes, and the body of the negative pressure air extraction pipe is connected to several air extraction joints. Each air extraction joint is connected to an air extraction branch pipe. The air extraction branch pipes and the air guide pipes are set in a one-to-one correspondence. An air extraction solenoid valve is set at the connection between the air extraction branch pipe and the air guide pipe. The air extraction solenoid valve is electrically connected to an external terminal.

[0013] As a further embodiment of the present invention: the extraction circulation pipeline includes an extraction separating pipe, an extraction inlet pipe, an extraction outlet pipe, and an extraction circulation pipe. The extraction separating pipes are respectively connected to the upper end of the upper circulation tank, and the extraction inlet pipe is connected to the lower end of the extraction tank. An extraction inlet solenoid valve is installed at the joint between the extraction inlet pipe and the two extraction separating pipes. A flow meter is connected to the body of the extraction inlet pipe. Both ends of the extraction outlet pipe are respectively connected to two circulation guide pipes, and an extraction outlet solenoid valve is installed at the joint between the extraction outlet pipe and the circulation guide pipe. The extraction circulation pipe is connected between the extraction tank and the body of the extraction outlet pipe. An extraction circulation solenoid valve is installed at the joint between the extraction circulation pipe and the extraction outlet pipe. An extraction circulation pump is also installed on the body of the extraction circulation pipe. The pump body of the extraction circulation pump is fixedly connected to the upper horizontal plate. The extraction inlet solenoid valve, the extraction outlet solenoid valve, the extraction circulation solenoid valve, and the extraction circulation pump are all electrically connected to an external terminal, and the flow meter is signal connected to the external terminal.

[0014] As a further embodiment of the present invention: the extraction circulation pipeline includes an extraction circulation pipe, an extraction outlet pipe, and an extraction inlet pipe. The two ends of the extraction circulation pipe are connected to the pipe bodies of the extraction outlet pipe and the extraction inlet pipe. An extraction circulation solenoid valve is installed at the connection point between the extraction circulation pipe and the extraction outlet pipe, and an extraction inlet solenoid valve is installed at the connection point between the extraction circulation pipe and the extraction inlet pipe. The two ends of the extraction outlet pipe are respectively connected to the pipe bodies of two circulation outlet pipes, and an extraction outlet solenoid valve is installed at the connection point between the extraction outlet pipe and the circulation outlet pipe. The two ends of the extraction inlet pipe are respectively connected to two upper circulation tanks. An extraction circulation pump is also installed on the pipe body of the extraction circulation pipe. The pump body of the extraction circulation pump is fixedly connected to the lower horizontal plate. A collection tank is correspondingly provided below the lower circulation tank, and the opening of the collection tank is located directly below each circulation outlet pipe. The extraction circulation pump, the extraction outlet solenoid valve, the extraction circulation solenoid valve, and the extraction inlet solenoid valve are all electrically connected to an external terminal.

[0015] The beneficial effects of this invention are: 1. This invention sets up multiple extraction mechanisms, which include an extraction tank, an upper circulation tank, an extraction tank, and a lower circulation tank connected sequentially from top to bottom. An extraction circulation pipeline is provided between the extraction tank and the upper circulation tank, and an extraction circulation pipeline is provided between the upper circulation tank and the lower circulation tank. The extraction tank, upper circulation tank, extraction tank, and lower circulation tank connected sequentially from top to bottom form a processing device that conforms to the principle of gravity-assisted fluid dynamics. The extraction and extraction steps are integrated through the upper circulation tank, lower circulation tank, and extraction and extraction circulation pipelines. This changes the traditional laboratory mode of multiple steps such as extraction, filtration, concentration, and purification, which are carried out separately. The extraction circulation pipeline and the extraction circulation pipeline can perform extraction and extraction cycles respectively, so that both extraction and extraction processes are optimized. It can transform the traditional single-path, single-mode extraction method into an extraction method that can support multiple complex workflows. It can provide different extraction schemes for simultaneously and efficiently dealing with the detection needs of two target substances with different physicochemical properties, aflatoxin and ochratoxin A. 2. In this invention, the upper and lower circulation tanks are arranged in a symmetrical configuration as two sets of circulation paths. When each of the two extraction tanks is connected to either circulation path, it is in a state of individual mycotoxin extraction; when the same extraction tank is connected to both circulation paths, it is in a state of co-extraction of mycotoxins. When one upper circulation tank and the extraction tank are in a state of circulation extraction via an extraction circulation pipeline, the other upper circulation tank, its connected extraction tank, and the lower circulation tank are in a state of circulation extraction via an extraction circulation pipeline. This configuration, where each of the two extraction tanks is connected to either circulation path, results in individual mycotoxin extraction. The device can have two independent parallel extraction channels, allowing for the use of optimized extraction solvents for aflatoxin and ochratoxin A, such as different pH values. Solutions of the same polarity can operate synchronously in a closed-loop system without interference, flowing through dedicated immunoaffinity extraction columns. This fundamentally overcomes the industry bottleneck of unsatisfactory recovery rates of one or more toxins when using a single extraction solution. When connected to two sets of circulation paths through the same extraction tank, it enables co-extraction of fungal toxins. An extraction tank containing composite immunoaffinity material is used, but extracts of different properties from two circulation paths are allowed to flow through the column according to a preset program, such as sequentially or alternately. This is suitable for sequentially extracting different target compounds from the same sample matrix, and the device can overlap the extraction steps of a single sample with those of another sample or the previous batch of extract from the same sample in time. While one sample is being extracted in the extraction tank, its prepared extract can be simultaneously purified by column passing in another loop, thereby reducing the overall sample pretreatment time by nearly half and significantly improving extraction efficiency. 3. The upper circulation tank of this invention is connected to a circulation guide pipe at its bottom. A negative pressure suction valve assembly, initially in a closed state, is installed inside the circulation guide pipe. The lower circulation tank is connected to a negative pressure suction pipe, and the extraction tank contains an extraction column. When the extractant in the extraction tank is drawn out through the negative pressure suction pipe to the point where it can no longer completely cover the extraction column, the negative pressure suction valve assembly opens due to the negative pressure suction from the negative pressure suction pipe. At the start of extraction, the negative pressure provided by the negative pressure suction pipe acts directly on the negative pressure suction valve assembly through the pipeline, causing it to overcome resistance such as spring force and open. Under pressure balance, the extractant stored in the upper circulation tank flows into the extraction tank in the form of a small stream. At this time, there is a certain liquid level in the extraction tank, which can completely cover the extraction column. The negative pressure provided by the negative pressure suction pipe acts on the extractant in the extraction tank, and the negative pressure suction valve assembly resets due to the weakening of the negative pressure. Driven by pressure, the liquid in the extraction tank continuously flows through the extraction column and is drawn to the lower circulation tank. The liquid level drops slowly and evenly, forming a small batch of liquid that comes into prolonged contact with the extraction column for extraction. Since the flow rate is controlled by negative pressure rather than gravity, this process can be very smooth. When the liquid level drops to just below the top of the extraction column, the negative pressure exposed on the liquid surface acts directly on the negative pressure suction valve assembly through the pipeline, rapidly drawing the extract stored in the upper circulation tank back into the extraction tank as a replenishing flow. This causes the liquid level to rise again and completely cover the extraction column. After the liquid level rises, the negative pressure suction valve assembly resets due to the weakening of the negative pressure. This forms an automatic circulating titration extraction, allowing the limited liquid to soak and penetrate the extraction column for a long time, providing sufficient time for the diffusion and binding of toxin molecules, thereby significantly improving the extraction recovery rate. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the connection structure between the extraction circulation pipeline and the upper circulation tank in this invention; Figure 3 This is a schematic diagram of the connection structure between the extraction circulation pipeline and the upper and lower circulation tanks of the present invention; Figure 4 This is a schematic diagram of the extraction circulation pipeline structure of the present invention; Figure 5 This is a schematic diagram of the extraction tank and the material-holding basket in their disassembled state according to the present invention; Figure 6 This is a schematic diagram of the internal structure of the extraction tank of the present invention; Figure 7 This is a schematic diagram of the liquid guiding ring structure of the present invention; Figure 8 This is a schematic diagram of the cross-sectional structure of the liquid guiding ring of the present invention; Figure 9 This is a schematic diagram of the cross-sectional structure of the bottom end of the circulating liquid guide tube of the present invention; Figure 10 For the present invention Figure 9 Schematic diagram of the structure at point A in the middle; Figure 11 This is a schematic diagram of the connection structure of the extraction tank in the individual extraction state of mycotoxins according to the present invention; Figure 12 This is a schematic diagram of the connection structure of the extraction tank in the co-extraction state of fungal toxins according to the present invention; Figure 13 This is a schematic diagram of the extraction tank structure for the individual extraction of mycotoxins according to the present invention; Figure 14 This is a schematic diagram of the extraction tank structure for the co-extraction of fungal toxins according to the present invention; Figure 15 This is a schematic diagram of the internal structure of the extraction tank of the present invention; Figure 16 This is a schematic cross-sectional view of the extraction tank of the present invention.

[0017] In the diagram: 1. Outer frame; 11. Upper horizontal plate; 12. Lower horizontal plate; 13. Vertical partition; 14. Slide rail slot; 2. Extraction tank; 21. Material basket; 22. Liquid guide ring; 23. Side wall support plate; 24. Bottom support plate; 25. Liquid level sensor; 26. Spray hole; 27. Annular cavity; 28. Inlet pipe; 3. Upper circulation tank; 31. Circulation guide pipe; 32. Upper connector assembly; 33. Sloping retaining ring; 34. Bottom sealing plate; 5. Connecting rod; 36. Upper limit plate; 37. First spring; 38. Inner groove surface; 39. Docking seat; 310. Sealing gasket; 311. Second spring; 4. Extraction tank; 41. Tank body push plate; 42. Tank body positioning hole; 43. Positioning ring; 44. Tank cover; 45. First inlet pipe; 46. First outlet pipe; 47. Inlet solenoid valve; 48. Second inlet pipe; 49. Outlet solenoid valve; 410. Second outlet pipe; 4 11. Positioning concave surface; 412. Bottom support mesh; 413. Upper limit mesh; 414. Inner inclined surface; 415. Extraction column; 5. Lower circulation tank; 51. Circulation inlet pipe; 52. Lower connector assembly; 53. Gas guide pipe; 54. Circulation outlet pipe; 6. Collection tank; 7. Negative pressure suction pipe; 71. Suction connector; 72. Suction branch pipe; 73. Suction solenoid valve; 8. Extraction circulation pipeline; 81. Extraction separator pipe; 82. Extraction inlet. 83. Solenoid valve; 84. Extraction inlet pipe; 85. Flow meter; 86. Extraction outlet solenoid valve; 87. Extraction outlet pipe; 88. Extraction circulation pipe; 89. Extraction circulation solenoid valve; 90. Extraction circulation pump; 91. Extraction circulation pipe; 92. Extraction circulation pump; 93. Extraction outlet pipe; 94. Extraction inlet pipe; 95. Extraction outlet solenoid valve; 96. Extraction circulation solenoid valve; 97. Extraction inlet solenoid valve. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0019] Example 1 like Figures 1 to 16 As shown, a solid-phase extraction device for detecting mycotoxins in food includes multiple extraction mechanisms. Each extraction mechanism comprises an extraction tank 2, an upper circulation tank 3, an extraction tank 4, and a lower circulation tank 5 connected sequentially from top to bottom. An extraction circulation pipeline 8 connects the extraction tank 2 and the upper circulation tank 3, and an extraction circulation pipeline 9 connects the upper circulation tank 3 and the lower circulation tank 5. This sequentially connected extraction tank 2, upper circulation tank 3, extraction tank 4, and lower circulation tank 5 constructs a processing device conforming to the principles of gravity-assisted fluid dynamics. The extraction and purification steps are conducted through the upper circulation tank 3 and the lower circulation tank 5. 5. The integration of extraction circulation pipeline 8 and extraction circulation pipeline 9 changes the traditional laboratory model of multiple separate and independent operations such as extraction, filtration, concentration and purification. Extraction circulation pipeline 8 and extraction circulation pipeline 9 can perform extraction circulation and extraction circulation respectively, so that the extraction process and extraction process can be optimized. It can transform from the traditional single-path and single-mode extraction method to an extraction method that can support a variety of complex workflows. It can provide different extraction solutions for simultaneously and efficiently dealing with the detection needs of two target substances with different physicochemical properties, aflatoxin and ochratoxin A. The upper circulation tank 3 and lower circulation tank 5 are arranged opposite each other as two sets of circulation paths. When the two extraction tanks 4 are connected to either circulation path, it is in a state of individual mycotoxin extraction; when the same extraction tank 4 is connected to both circulation paths, it is in a state of co-extraction of mycotoxins. When one upper circulation tank 3 and extraction tank 2 are in a state of circulation extraction through extraction circulation pipeline 8, the other upper circulation tank 3, its connected extraction tank 4, and lower circulation tank 5 are in a state of circulation extraction through extraction circulation pipeline 9. With the configuration of individual mycotoxin extraction when the two extraction tanks 4 are connected to either circulation path, the device can have two independent parallel extraction channels, allowing for the use of optimized extraction solvents for aflatoxin and ochratoxin A, such as different pH values. Solutions of different polarities can operate synchronously in a closed-loop system without interference, flowing through dedicated immunoaffinity extraction columns. This fundamentally overcomes the industry bottleneck of unsatisfactory recovery rates of one or more toxins when using a single extraction solution. When connected to two sets of circulation paths through the same extraction tank 4, it is configured for co-extraction of fungal toxins. An extraction tank 4 containing composite immunoaffinity material is used, but extracts of different properties from two circulation paths are allowed to flow through the column according to a preset program, such as sequentially or alternately. This is suitable for sequentially extracting different target compounds from the same sample matrix, and the device can overlap the extraction steps of a single sample with the extraction steps of another sample or the previous batch of extract from the same sample in time. While one sample is being extracted in extraction tank 2, its prepared extract can be simultaneously purified by column passing in another loop, thereby reducing the overall sample pretreatment time by nearly half and greatly improving extraction efficiency. The bottom of the upper circulation tank 3 is connected to a circulation guide pipe 31, and a negative pressure suction valve assembly, initially in a closed state, is installed inside the circulation guide pipe 31. The lower circulation tank 5 is connected to a negative pressure suction pipe 7, and the extraction tank 4 is equipped with an extraction column 415. When the extract in the extraction tank 4 is drawn out through the negative pressure suction pipe 7 to the point where it can no longer completely cover the extraction column 415, the negative pressure suction valve assembly opens through the negative pressure suction of the negative pressure suction pipe 7. At the start of extraction, the negative pressure provided by the negative pressure suction pipe 7 acts directly on the negative pressure suction valve assembly through the pipeline, causing it to overcome the resistance such as spring force and open. Under the action of pressure balance, the extract stored in the upper circulation tank 3 flows into the extraction tank 4 in the form of a small stream. At this time, there is a certain liquid level in the extraction tank 4, which can completely cover the extraction column 415. The negative pressure provided by the negative pressure suction pipe 7 acts on the extract in the extraction tank 4. The negative pressure suction valve assembly resets due to the weakening of the negative pressure. Driven by pressure, the liquid in the extraction tank 4 continuously flows through the extraction column 415 and is drawn to the lower circulation tank 5. The liquid level drops slowly and evenly, forming a small batch of liquid that is in long-term contact with the extraction column 415 for extraction. Since the flow rate is controlled by negative pressure rather than gravity, this process can be very smooth. When the liquid level drops to just below the top of the extraction column 415, the negative pressure exposed on the liquid surface acts directly on the negative pressure suction valve assembly through the pipeline, causing the extract stored in the upper circulation tank 3 to flow back into the extraction tank 4 as a replenishing liquid flow, so that the liquid level rises again to completely cover the extraction column 415. After the liquid level rises, the negative pressure suction valve assembly resets due to the weakening of the negative pressure effect. This forms an automatic circulating titration extraction, allowing the limited liquid to soak and penetrate the extraction column 415 for a long time, providing sufficient diffusion and binding time for toxin molecules, thereby significantly improving the extraction recovery rate.

[0020] Example 2 Improvements based on Example 1: like Figure 1 , Figure 5 , Figure 6 , Figure 7 and Figure 8As shown, the device also includes an outer frame 1. A horizontally arranged upper horizontal plate 11 and a lower horizontal plate 12 are fixedly connected inside the frame of the outer frame 1. An extraction tank 2 is fixedly connected to the top of the frame of the outer frame 1. The body of the upper circulation tank 3 is fixedly connected through the upper horizontal plate 11, and the body of the lower circulation tank 5 is fixedly connected through the lower horizontal plate 12. A vertically arranged vertical partition 13 is also fixedly connected inside the frame of the outer frame 1. The vertical partition 13 is located between adjacent extraction mechanisms. By setting the outer frame 1 to provide a supporting skeleton for the entire device, the upper circulation tank 3 is fixedly fixed through the upper horizontal plate 11, and the lower circulation tank 5 is fixedly fixed through the lower horizontal plate 12, thus achieving a secure installation of the tanks. The vertical partition 13, located between adjacent extraction mechanisms, serves as a physical separator, and the vertical partition 13 also provides a basic boundary for the installation track of the sliding tank push plate 41.

[0021] Furthermore, a material-holding mesh basket 21 is movably installed inside the extraction tank 2. Several side wall support plates 23 are connected in a ring shape to the inner wall of the extraction tank 2. The side wall support plates 23 abut against the outer side of the material-holding mesh basket 21. Several bottom support plates 24 are connected in a ring shape to the bottom surface of the extraction tank 2. The bottom support plates 24 support the bottom of the material-holding mesh basket 21. A liquid-guiding ring 22 is fixedly connected to the inner wall of the extraction tank 2. The liquid-guiding ring 22 is installed above the material-holding mesh basket 21 inside the extraction tank 2. An annular cavity 27 is formed inside the liquid-guiding ring 22. The inner ring of the liquid guiding ring 22 has several spray holes 26 connected to the annular cavity 27. The spray holes 26 are arranged vertically in groups of three, and the opening angles of each group of spray holes 26 are, from top to bottom, upward, horizontal, and downward, respectively. The outer ring of the liquid guiding ring 22 is connected to an inlet pipe 28 connected to the annular cavity 27. A liquid level sensor 25 is also fixedly connected to the inner wall of the extraction tank 2. The liquid level sensor 25 is connected to an external terminal via a signal connection. The material basket 21 allows solid samples, such as crushed kernels, to be... Contained in a porous container, the material basket 21 containing solid residue can be easily removed as a whole after extraction, simplifying the cleaning process and preventing residue from clogging the pipeline. The annular design of the side wall support plate 23 and the bottom support plate 24 provides multi-point support for the material basket 21, ensuring that the material basket 21 is fixed in position within the extraction tank 2, thereby ensuring that the extractant can flow evenly through the sample and avoiding extraction dead zones. After the extractant enters the annular cavity 27 through the inlet pipe 28, it can be evenly distributed throughout the entire extraction tank 2 from the circumferential direction. In cross-section, the three spray holes 26 are arranged in a group with different angles of upward, horizontal and downward inclination, which allows the extract to be sprayed evenly over a large area on the sample. This ensures that the extract can fully contact the sample in every corner of the extraction tank 2, maximizing the speed and efficiency of the leaching of the target toxin from the solid matrix. The liquid level sensor 25 enables real-time monitoring of the liquid volume in the extraction tank 2, ensuring that the operator or external terminal can accurately grasp the amount of extract and ensure that the extraction process is carried out at the set liquid-to-solid ratio.

[0022] like Figure 1 , Figure 2 , Figure 3 , Figure 9 and Figure 10As shown, the upper connector assembly 32 for sealing and docking with the extraction tank 4 is sleeved on the body of the circulation guide pipe 31 connected to the bottom of the upper circulation tank 3. The upper connector assembly 32 includes an inner groove surface 38, a docking seat 39, a sealing gasket 310, and a second spring 311. The inner groove surface 38 is opened on the outer wall of the circulation guide pipe 31. The docking seat 39 and the second spring 311 are both movably sleeved on the inner groove surface 38, and the second spring 311 abuts against the lower part of the docking seat 39. The sealing gasket 310 is fixedly connected to the inner side of the docking seat 39. The negative pressure suction valve assembly installed inside the circulating liquid guide tube 31 includes a beveled retaining ring 33, a bottom sealing plate 34, a connecting rod 35, an upper limit plate 36, and a first spring 37. The beveled retaining ring 33 is fixedly connected to the inner wall of the circulating liquid guide tube 31. The rod body of the connecting rod 35 moves through the beveled retaining ring 33. The upper end of the connecting rod 35 is fixedly connected to the upper limit plate 36, and the lower end of the connecting rod 35 is fixedly connected to the bottom sealing plate 34. The rod body of the connecting rod 35 is fitted with the first spring 37, and the first spring 37 abuts against the beveled retaining ring 33 and the upper limit plate 36. When the connecting rod is engaged... When removing tank 4, connect the inlet of the circulating liquid guide pipe 31 to the inlet of the extraction tank 4. This achieves initial connection between the two ports. After being pressed, the docking seat 39 slides along the inner groove surface 38 and compresses the second spring 311. The sealing gasket 310 on its inner side deforms and fits tightly against the docking part, forming a reliable seal. The elastic force provided by the second spring 311 ensures the continuous pressure of the seal, facilitating the reconnection of the required pipelines when switching between the two states of individual extraction and co-extraction. The negative pressure suction valve assembly inside the circulating liquid guide pipe 31... When the liquid level is sufficient, the elastic force of the first spring 37 pushes the upper limit plate 36 and the connecting rod 35, causing the bottom sealing plate 34 to tightly seal and block the inclined retaining ring 33, preventing the liquid in the upper circulation tank 3 from flowing freely downwards, thereby controlling the liquid flow. When the liquid level in the extraction tank 4 drops, the negative pressure applied by the negative pressure suction pipe 7 acts below the bottom sealing plate 34. If the liquid level drops to a certain level, the negative pressure overcomes the elastic force of the first spring 37 and sucks the bottom sealing plate 34 open, allowing the liquid in the upper circulation tank 3 to quickly flow into the extraction tank 4 for replenishment under the action of gravity or pressure difference.

[0023] Furthermore, the upper end of the lower circulation tank 5 is connected to a circulation inlet pipe 51, and a lower connector assembly 52 for sealing and connecting the extraction tank 4 is fitted on the body of the circulation inlet pipe 51. The lower connector assembly 52 has the same structure as the upper connector assembly 32. The lower end of the lower circulation tank 5 is connected to a circulation outlet pipe 54. The lower connector assembly 52 ensures that the bottom outlet of the extraction tank 4 can also be sealed and connected in the same fast way.

[0024] like Figure 1 , Figure 3 , Figures 11 to 16As shown, the inner wall of the extraction tank 4 has an inner inclined surface 414. An extraction column 415 is movably installed inside the extraction tank 4, and the shape of the extraction column 415 matches the inner inclined surface 414 of the extraction tank 4. A bottom support net 412 is connected to the bottom of the extraction tank 4. A tank cover 44 is threadedly connected to the upper end of the extraction tank 4. An upper limit net 413 is fixedly connected inside the tank cover 44. When the tank cover 44 and the extraction tank 4 are in a threaded connection state, the extraction column 415 fits against the inner inclined surface 414 of the extraction tank 4, and the extraction column 415 is clamped between the bottom support net 412 and the upper limit net 413. A tank body push plate 41 is provided on the outer side of the extraction tank 4. The tank body push plate 41 has three tank body positioning holes 42 arranged side by side. When extracting fungal toxins individually, the two extraction tanks 4 are respectively inserted into the positioning holes 42 on both sides of the tank body, and the extraction columns 415 installed in the two extraction tanks 4 are respectively aflatoxin extraction columns and ochratoxin extraction columns; when extracting fungal toxins together, the extraction tanks 4 are respectively inserted into the positioning hole 42 in the middle of the tank body, and the extraction columns 415 installed in the extraction tank 4 are composite immunoaffinity extraction columns; a positioning rubber ring 43 is embedded in the inner wall of the positioning hole 42 of the tank body, and a positioning concave surface 411 is opened on the outer wall of the extraction tank 4. The positioning rubber ring 43 is inserted into the positioning concave surface 411 when the extraction tank 4 is inserted into the positioning hole 42 of the tank body; the inner walls on both sides of the outer frame 1 and the vertical partition 13 Both sides of the plate are fixedly connected with slide rail slots 14. The two sides of the tank push plate 41 are movably locked in the slide rail slots 14. The inner inclined surface 414 of the inner wall of the extraction tank 4 matches the shape of the extraction column 415. When the extraction column 415 is placed in the extraction tank 4 and subjected to axial compression, the inclined surface of the extraction column 415 and the inner inclined surface 414 fit tightly together, ensuring that the extraction column 415 is in a central position, producing a good radial seal. This forces the liquid to flow entirely through the packing layer inside the extraction column 415, without bypassing the gap between the column wall and the tank wall, thus ensuring 100% column bed utilization and consistent extraction efficiency. The bottom support net 412 and the upper limit net 413 firmly clamp the extraction column 415 in the middle, preventing it from... The can move or deform under the impact of the liquid flow, while allowing the liquid to pass freely. The positioning holes 42 on both sides correspond to the individual extraction state and are used to place two extraction cans 4 respectively containing aflatoxin extraction columns and ochratoxin extraction columns. The positioning hole 42 in the middle corresponds to the common extraction state and is used to place one extraction can 4 containing a composite immunoaffinity extraction column. By simply sliding the can body push plate 41 laterally, different extraction cans 4 can be accurately brought into the position where they are connected with the fixed position of the circulation guide pipe 31 and circulation inlet pipe 51. The engagement of the positioning rubber ring 43 with the positioning concave surface 411 provides additional friction positioning after the extraction can 4 is inserted into the can body positioning hole 42, preventing it from accidentally falling off or rotating.

[0025] Furthermore, in the individual extraction state of mycotoxins, the caps 44 of the two extraction tanks 4 are connected by threads and are connected to the first inlet pipes 45. The other ends of the two first inlet pipes 45 are connected to the circulating guide pipes 31, and the first inlet pipes 45 and the circulating guide pipes 31 are sealed together by the upper connector assembly 32. The bottom ends of the two extraction tanks 4 are connected to the first outlet pipes 46, and the other ends of the two first outlet pipes 46 are connected to the circulating inlet pipes 51, and the first outlet pipes 46 and the circulating inlet pipes 51 are sealed together by the lower connector assembly 52. ​​In the individual extraction state, each extraction tank 4 is connected to the corresponding circulating guide pipes 31 and circulating inlet pipes 51 through a single first inlet pipe 45 and first outlet pipe 46, forming an independent closed loop flow path, which is suitable for the individual extraction process that requires high-efficiency circulation. When in the state of co-extraction of fungal toxins, the threaded cap 44 of the extraction tank 4 is connected to two second inlet pipes 48. The mating parts of the two second inlet pipes 48 and the cap 44 are connected to inlet solenoid valves 47. The other ends of the two second inlet pipes 48 are connected to the circulation guide pipe 31, and the second inlet pipes 48 and the circulation guide pipe 31 are sealed together by an upper connector assembly 32. The bottom end of the extraction tank 4 is connected to two second outlet pipes 410. The mating parts of the two second outlet pipes 410 and the extraction tank 4 are connected to outlet solenoid valves 49. The other ends of the two second outlet pipes 410 are connected to the circulation guide pipe 31. The inlet pipe 51 is connected to the outlet pipe 410 and the circulation inlet pipe 51 are sealed together through the lower connector assembly 52. ​​The inlet solenoid valve 47 and the outlet solenoid valve 49 are both electrically connected to the external terminal. During extraction, a single extraction tank 4 can selectively connect to two independent circulation paths on the left and right at the same time. By controlling the switching combination of the inlet solenoid valve 47 and the outlet solenoid valve 49 through the external terminal, it is possible to allow the extract from the left loop or the extract from the right loop to flow through the extraction column 415 at different times, or to achieve complex processes such as sequential passage and alternating rinsing of the two liquids.

[0026] like Figure 1 and Figure 3As shown, the upper ends of the pipe walls of the two lower circulation tanks 5 are connected to air guide pipes 53. The body of the negative pressure suction pipe 7 is connected to several suction connectors 71. Each suction connector 71 is connected to a suction branch pipe 72. The suction branch pipe 72 is set one-to-one with the air guide pipe 53. A suction solenoid valve 73 is set at the connection between the suction branch pipe 72 and the air guide pipe 53. The suction solenoid valve 73 is electrically connected to an external terminal. A negative pressure source, such as a vacuum pump, can act on multiple lower circulation tanks 5 through the negative pressure suction pipe 7. By opening the suction solenoid valve 73 on the corresponding suction branch pipe 72, negative pressure can be applied to the designated lower circulation tank 5 and the extraction tank 4 connected to it. In the individual extraction state, the use of negative pressure and the magnitude of negative pressure in the two loops can be controlled independently. In the joint extraction state, the negative pressure can also be guided to the currently working loop by switching the valve according to the process requirements. Secondly, the vacuum solenoid valve 73 is electrically connected to an external terminal so that the valve can be opened and closed through the external terminal to control the negative pressure of a specific loop, and the flow rate of the extractant through the extraction column 415 can be controlled.

[0027] like Figure 1 and Figure 2 As shown, the extraction circulation pipeline 8 includes an extraction separating pipe 81, an extraction inlet pipe 83, an extraction outlet pipe 86, and an extraction circulation pipe 87. The extraction separating pipe 81 is connected to the upper end of the upper circulation tank 3. The extraction inlet pipe 83 is connected to the lower end of the extraction tank 2. An extraction inlet solenoid valve 82 is installed at the connection point between the extraction inlet pipe 83 and the two extraction separating pipes 81. A flow meter 84 is connected to the body of the extraction inlet pipe 83. Both ends of the extraction outlet pipe 86 are connected to two circulation guide pipes 31, and an extraction outlet solenoid valve 85 is installed at the connection point between the extraction outlet pipe 86 and the circulation guide pipes 31. The extraction circulation pipe 87 connects the extraction tank 2 and the body of the extraction outlet pipe 86. An extraction circulation pipe 87 is installed at the connection point between the extraction circulation pipe 87 and the extraction outlet pipe 86. The extraction circulation tube 87 is equipped with an extraction circulation solenoid valve 88 and an extraction circulation pump 89. The pump body of the extraction circulation pump 89 is fixedly connected to the upper horizontal plate 11. The extraction inlet solenoid valve 82, the extraction outlet solenoid valve 85, the extraction circulation solenoid valve 88, and the extraction circulation pump 89 are all electrically connected to an external terminal. The flow meter 84 is signal-connected to the external terminal, realizing multi-mode control of the extraction process in the extraction tank 2. The installation of the flow meter 84 provides real-time monitoring data of the extraction liquid flow rate and is signal-connected to the external terminal, enabling the external terminal to adjust the pump speed or determine whether the pipeline is unobstructed according to the actual flow rate. Furthermore, by controlling the opening and closing of the corresponding valves, the extraction liquid in the corresponding pipeline can be circulated, realizing the circulatory extraction of the sample.

[0028] like Figure 1 , Figure 3 and Figure 4As shown, the extraction circulation pipeline 9 includes an extraction circulation pipe 91, an extraction outlet pipe 93, and an extraction inlet pipe 94. Both ends of the extraction circulation pipe 91 are connected to the bodies of the extraction outlet pipe 93 and the extraction inlet pipe 94. An extraction circulation solenoid valve 96 is installed at the connection point between the extraction circulation pipe 91 and the extraction outlet pipe 93, and an extraction inlet solenoid valve 97 is installed at the connection point between the extraction circulation pipe 91 and the extraction inlet pipe 94. Both ends of the extraction outlet pipe 93 are connected to the bodies of two circulation outlet pipes 54, and an extraction outlet solenoid valve 95 is installed at the connection point between the extraction outlet pipe 93 and the circulation outlet pipe 54. Both ends of the extraction inlet pipe 94 are connected to two upper circulation tanks 3. An extraction circulation pump 92 is also installed on the body of the extraction circulation pipe 91, and the pump body of the extraction circulation pump 92 is fixedly connected to the lower horizontal plate 12. Below the lower circulation tank 5, a collection tank 6 is correspondingly provided, and the opening of the collection tank 6 is located directly below each circulation outlet pipe 54. The extraction circulation pump 92, extraction outlet solenoid valve 95, extraction circulation solenoid valve 96, and extraction inlet solenoid valve 97 are all electrically connected to external terminals to realize dynamic column extraction. The extraction outlet solenoid valve 95, extraction circulation solenoid valve 96, and extraction inlet solenoid valve 97 installed on the pipeline play a role in flow path guidance and control. By controlling the opening and closing combination of these valves, the liquid in the lower circulation tank 5 can be pumped back to the upper circulation tank 3 to complete one cycle; or, when needed, the liquid in the loop can be discharged into the collection tank 6 below through the extraction outlet pipe 93 and the circulation outlet pipe 54. This not only significantly improves work efficiency but also eliminates the inconsistency caused by manual operation.

[0029] Working principle: The extraction tank 2, upper circulation tank 3, extraction tank 4 and lower circulation tank 5 are stably connected from top to bottom by the support of the outer frame 1, upper horizontal plate 11 and lower horizontal plate 12, forming a vertical workflow. The sample holding basket 21 in the extraction tank 2 is fixed by the side wall support plate 23 and the bottom support plate 24. The liquid guiding ring 22 above it sprays the extractant at multiple angles through the spray hole 26 to ensure full extraction. The liquid level is monitored by the liquid level sensor 25. The device has two switchable operating modes, achieved by moving the tank pusher plate 41. When the two extraction tanks 4 are respectively engaged with the positioning holes 42 on both sides of the tank, the device enters the individual extraction state for mycotoxins. At this time, the two extraction tanks 4 are respectively equipped with aflatoxin-specific extraction columns and ochratoxin-specific extraction columns. The two independent circulation paths operate synchronously. The extract in one path is driven by the extraction circulation pump 89 and circulates between the extraction tank 2 and the corresponding upper circulation tank 3 through the extraction circulation pipeline 8 to achieve the extraction of the first toxin. The extracted liquid enters one of the extraction tanks through the circulation guide pipe 31 at the bottom of the circulation tank 3 on this path. 4. After specific adsorption by the extraction column 415, the extract flows into the lower circulation tank 5. After all the extract in the upper circulation tank 3 is extracted, the extract is transported back to the upper circulation tank 3 through the extraction circulation pipeline 9. At the same time, the extract from another path circulates between the extraction tank 2 and the other upper circulation tank 3 through the extraction circulation pipeline 8 driven by the extraction circulation pump 89, thereby realizing the extraction of the second toxin. At this time, the extract of the second toxin enters the extraction process, and the extract of the first toxin after extraction enters the extraction tank 2 again through the extraction circulation pipeline 8 for secondary extraction, which can realize repeated extraction and extraction. When the push plate 41 slides to make the single extraction tank 4 engage with the positioning hole 42 in the middle tank, the device enters the state of co-extraction of fungal toxins. At this time, the composite immunoaffinity extraction column is placed in the extraction tank 4. By controlling the opening and closing sequence of the liquid inlet solenoid valve 47 and the liquid outlet solenoid valve 49, the extracts with different properties from the two independent extraction loops on the left and right sides can flow through the same composite extraction column 415 in a preset gradient sequence or alternately, so as to achieve sequential extraction and co-purification of multiple toxins in the same sample. During the extraction process, the negative pressure provided by the negative pressure suction pipe 7 acts directly on the negative pressure suction valve assembly through the pipeline, causing it to overcome resistance such as spring force and open. Under the action of pressure balance, the extract stored in the upper circulation tank 3 flows into the extraction tank 4 in the form of a small stream. At this time, there is a certain liquid level in the extraction tank 4, which can completely cover the extraction column 415. The negative pressure provided by the negative pressure suction pipe 7 acts on the extract in the extraction tank 4. The negative pressure suction valve assembly resets due to the weakening of the negative pressure. Driven by the negative pressure, the extraction tank 4... The liquid inside continuously flows through the extraction column 415 and is drawn to the lower circulation tank 5. When the liquid level drops to just below the top of the extraction column 415, the negative pressure exposed on the liquid surface acts directly on the negative pressure suction valve assembly through the pipeline, causing the extract stored in the upper circulation tank 3 to flow rapidly into the extraction tank 4 as a replenishing liquid flow, so that the liquid level rises again to completely cover the extraction column 415. After the liquid level rises, the negative pressure suction valve assembly resets again due to the weakening of the negative pressure effect, thus forming an automatic circulating titration extraction.

[0030] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0031] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A solid-phase extraction device for detecting mycotoxins in food, comprising multiple extraction mechanisms, characterized in that: The extraction mechanism includes an extraction tank (2), an upper circulation tank (3), an extraction tank (4), and a lower circulation tank (5) connected sequentially from top to bottom. An extraction circulation pipeline (8) is provided between the extraction tank (2) and the upper circulation tank (3), and an extraction circulation pipeline (9) is provided between the upper circulation tank (3) and the lower circulation tank (5). The upper circulation tank (3) and the lower circulation tank (5) are arranged in opposite positions as two sets of circulation paths. When the two extraction tanks (4) are connected to either circulation path, the fungal toxin is extracted individually. When the same extraction tank (4) is connected to both sets of circulation paths, the fungal toxin is extracted together. When one of the upper circulation tanks (3) and the extraction tank (2) are in the circulation extraction state through the extraction circulation pipeline (8), the other upper circulation tank (3) is in the circulation extraction state through the extraction circulation pipeline (9) and the extraction tank (4) and the lower circulation tank (5) connected to it. The bottom of the upper circulation tank (3) is connected to a circulation guide pipe (31), and a negative pressure suction valve assembly that is initially closed is installed inside the circulation guide pipe (31). The lower circulation tank (5) is connected to a negative pressure suction pipe (7), and an extraction column (415) is installed inside the extraction tank (4). When the extract in the extraction tank (4) is drawn out through the negative pressure suction pipe (7) to the point that it cannot completely cover the extraction column (415), the negative pressure suction valve assembly is opened through the negative pressure suction of the negative pressure suction pipe (7).

2. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 1, characterized in that: The device also includes an outer frame (1), in which an upper horizontal plate (11) and a lower horizontal plate (12) are fixedly connected in a horizontal position. The extraction tank (2) is fixedly connected to the top of the outer frame (1). The upper circulation tank (3) is fixedly connected in a through-hole position to the upper horizontal plate (11). The lower circulation tank (5) is fixedly connected in a through-hole position to the lower horizontal plate (12). A vertical partition (13) is also fixedly connected in a vertical position inside the outer frame (1). The vertical partition (13) is located between adjacent extraction mechanisms.

3. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 1, characterized in that: The extraction tank (2) has a movably mounted material-holding mesh basket (21) inside. The inner wall of the extraction tank (2) is connected in a ring shape with several side wall support plates (23), which abut against the outer side of the material-holding mesh basket (21). The bottom surface of the extraction tank (2) is connected in a ring shape with several bottom support plates (24), which support the bottom surface of the material-holding mesh basket (21) below. A liquid-guiding ring (22) is fixedly connected to the inner wall of the extraction tank (2). The liquid-guiding ring (22) is installed above the material-holding mesh basket (21) inside the extraction tank (2). (22) An annular cavity (27) is provided inside. The inner ring of the liquid guiding ring (22) is provided with several spray holes (26) that communicate with the annular cavity (27). The spray holes (26) are arranged vertically in groups of three. The opening angle of each group of spray holes (26) is inclined upward, horizontal and inclined downward respectively from top to bottom. The outer ring of the liquid guiding ring (22) is connected to the liquid inlet pipe (28) that communicates with the annular cavity (27). The inner wall of the extraction tank (2) is also fixedly connected to a liquid level sensor (25). The liquid level sensor (25) is connected to an external terminal in a signal connection.

4. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 2, characterized in that: The upper connector assembly (32) for sealing and docking with the extraction tank (4) is fitted onto the body of the circulating liquid guide pipe (31) connected to the bottom end of the upper circulation tank (3). The upper connector assembly (32) includes an inner groove surface (38), a docking seat (39), a sealing gasket (310), and a second spring (311). The inner groove surface (38) is opened on the outer wall of the circulating liquid guide pipe (31). The docking seat (39) and the second spring (311) are both movably fitted onto the inner groove surface (38), and the second spring (311) abuts against the lower part of the docking seat (39). The sealing gasket (310) is fixedly connected to the inner side of the docking seat (39). The negative pressure suction valve assembly installed inside the circulating liquid guide tube (31) includes a beveled retaining ring (33), a bottom sealing plate (34), a connecting rod (35), an upper limit plate (36), and a first spring (37). The beveled retaining ring (33) is fixedly connected to the inner wall of the circulating liquid guide tube (31). The rod body of the connecting rod (35) moves through the beveled retaining ring (33). The upper end of the connecting rod (35) is fixedly connected to the upper limit plate (36), and the lower end of the connecting rod (35) is fixedly connected to the bottom sealing plate (34). The rod body of the connecting rod (35) is fitted with the first spring (37), and the first spring (37) abuts between the beveled retaining ring (33) and the upper limit plate (36).

5. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 4, characterized in that: The upper end of the lower circulation tank (5) is connected to a circulation inlet pipe (51), and a lower connector assembly (52) for sealing and docking with the extraction tank (4) is fitted on the body of the circulation inlet pipe (51). The lower connector assembly (52) has the same structure as the upper connector assembly (32), and the lower end of the lower circulation tank (5) is connected to a circulation outlet pipe (54).

6. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 5, characterized in that: The inner wall of the extraction tank (4) is provided with an inner inclined surface (414). An extraction column (415) is movably arranged inside the extraction tank (4), and the shape of the extraction column (415) matches the inner inclined surface (414) of the extraction tank (4). A bottom support net (412) is connected to the bottom of the extraction tank (4), and a tank cover (44) is threadedly connected to the upper end of the extraction tank (4). An upper limit net (413) is fixedly connected inside the tank cover (44). When the lid (44) and the extraction tank (4) are in a threaded connection state, the extraction column (415) fits against the inner inclined surface (414) of the extraction tank (4), and the extraction column (415) is clamped between the bottom support net (412) and the upper limit net (413); a tank body push plate (41) is provided on the outer side of the extraction tank (4), and the tank body push plate (41) has three tank body positioning holes (42) arranged side by side; when in the state of separate extraction of fungal toxins, the two The extraction tanks (4) are respectively inserted into the positioning holes (42) on both sides of the tank body, and the extraction columns (415) installed in the two extraction tanks (4) are respectively aflatoxin extraction columns and ochratoxin extraction columns; when in the state of co-extraction of fungal toxins, the extraction tanks (4) are respectively inserted into the positioning hole (42) in the middle of the tank body, and the extraction column (415) installed in the extraction tank (4) is a composite immunoaffinity extraction column; the positioning holes (42) of the tank body The inner wall of the hole is embedded with a positioning rubber ring (43), and the outer wall of the extraction tank (4) is provided with a positioning concave surface (411). When the extraction tank (4) is inserted into the positioning hole (42) of the tank body, the positioning rubber ring (43) is stuck in the positioning concave surface (411). The inner walls of both sides of the frame (1) and the two sides of the vertical partition (13) are fixedly connected with slide rail slots (14). The two sides of the tank body push plate (41) are movably stuck in the slide rail slots (14).

7. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 6, characterized in that: When the fungal toxin is extracted separately, the two extraction tanks (4) are connected by a first inlet pipe (45) through the threaded tank cover (44). The other end of the two first inlet pipes (45) is connected to the circulating liquid guide pipe (31), and the first inlet pipe (45) and the circulating liquid guide pipe (31) are sealed together by the upper connector assembly (32). The bottom end of the two extraction tanks (4) is connected to a first outlet pipe (46), and the other end of the two first outlet pipes (46) is connected to the circulating liquid inlet pipe (51), and the first outlet pipe (46) and the circulating liquid inlet pipe (51) are sealed together by the lower connector assembly (52). When in the state of co-extraction of fungal toxins, the extraction tank (4) is connected to the tank cover (44) with two second liquid inlet pipes (48). The two second liquid inlet pipes (48) are connected to the tank cover (44) with a liquid inlet solenoid valve (47). The other end of the two second liquid inlet pipes (48) is connected to the circulating liquid guide pipe (31). The second liquid inlet pipe (48) and the circulating liquid guide pipe (31) are sealed and connected by an upper connector assembly (32). The bottom end of the extraction tank (4) is connected to two second liquid outlet pipes (410). The two second liquid outlet pipes (410) are connected to the extraction tank (4) with a liquid outlet solenoid valve (49). The other end of the two second liquid outlet pipes (410) is connected to the circulating liquid inlet pipe (51). The second liquid outlet pipe (410) and the circulating liquid inlet pipe (51) are sealed and connected by a lower connector assembly (52). The liquid inlet solenoid valve (47) and the liquid outlet solenoid valve (49) are both electrically connected to an external terminal.

8. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 5, characterized in that: The upper ends of the pipe walls of the two lower circulation tanks (5) are connected to air guide pipes (53). The body of the negative pressure suction pipe (7) is connected to several suction connectors (71). Each suction connector (71) is connected to a suction branch pipe (72). The suction branch pipe (72) and the air guide pipe (53) are arranged in a one-to-one correspondence. The connection between the suction branch pipe (72) and the air guide pipe (53) is provided with a suction solenoid valve (73). The suction solenoid valve (73) is electrically connected to an external terminal.

9. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 2, characterized in that: The extraction circulation pipeline (8) includes an extraction separator (81), an extraction inlet pipe (83), an extraction outlet pipe (86), and an extraction circulation pipe (87). The extraction separator (81) is connected to the upper end of the upper circulation tank (3), and the extraction inlet pipe (83) is connected to the lower end of the extraction tank (2). An extraction inlet solenoid valve (82) is installed at the joint between the extraction inlet pipe (83) and the two extraction separators (81). A flow meter (84) is connected to the body of the extraction inlet pipe (83). The two ends of the extraction outlet pipe (86) are connected to two circulation guide pipes (31), and the extraction outlet pipe (86) and the circulation guide pipe (31) are connected to each other. An extraction solenoid valve (85) is installed at the connection point. The extraction circulation pipe (87) is connected between the extraction tank (2) and the extraction outlet pipe (86). An extraction circulation solenoid valve (88) is installed at the connection point between the extraction circulation pipe (87) and the extraction outlet pipe (86). An extraction circulation pump (89) is also installed on the pipe body of the extraction circulation pipe (87). The pump body of the extraction circulation pump (89) is fixedly connected to the upper horizontal plate (11). The extraction inlet solenoid valve (82), the extraction outlet solenoid valve (85), the extraction circulation solenoid valve (88), and the extraction circulation pump (89) are all electrically connected to the external terminal. The flow meter (84) is signal connected to the external terminal.

10. The solid-phase extraction apparatus for detecting mycotoxins in food according to claim 5, characterized in that: The extraction circulation pipeline (9) includes an extraction circulation pipe (91), an extraction outlet pipe (93), and an extraction inlet pipe (94). Both ends of the extraction circulation pipe (91) are connected to the bodies of the extraction outlet pipe (93) and the extraction inlet pipe (94). An extraction circulation solenoid valve (96) is installed at the connection point between the extraction circulation pipe (91) and the extraction outlet pipe (93), and an extraction inlet solenoid valve (97) is installed at the connection point between the extraction circulation pipe (91) and the extraction inlet pipe (94). Both ends of the extraction outlet pipe (93) are connected to the bodies of two circulation outlet pipes (54), respectively. The extraction outlet pipe (93) and the circulation outlet pipe (54)... The extraction outlet solenoid valve (95) is installed at the docking part of the extraction inlet pipe (94). The two ends of the extraction inlet pipe (94) are respectively connected to the two upper circulation tanks (3). The extraction circulation pipe (91) is also equipped with an extraction circulation pump (92). The pump body of the extraction circulation pump (92) is fixedly connected to the lower horizontal plate (12). A collection tank (6) is set below the lower circulation tank (5). The opening of the collection tank (6) is located directly below each circulation outlet pipe (54). The extraction circulation pump (92), extraction outlet solenoid valve (95), extraction circulation solenoid valve (96) and extraction inlet solenoid valve (97) are all electrically connected to the external terminal.

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