A sample pretreatment device for rapid detection of heavy metals in food

Abstract

The utility model provides a kind of food heavy metal rapid detection's sample pretreatment device, it is related to food detection technical field, including sealed pipe body, the inside of sealed pipe body is coaxially communicated from top to bottom and is provided with homogenizing chamber, settlement interception chamber, membrane filtration chamber and quantitative liquid outlet chamber, the utility model is integrated homogenizing chamber, settlement interception chamber, membrane filtration chamber and quantitative liquid outlet chamber from top to bottom in single sealed pipe body, the sample homogenization needed for food heavy metal detection, closed digestion, gradient settlement interception, composite membrane purification precision filtration, quantitative liquid whole process, all are completed in closed cavity, whole process does not need to open cover and transfer sample and extract, eliminate the residue loss of the heavy metal pipe wall to be measured caused by multiple container transfer, cross contamination caused by environment, appliance is avoided simultaneously, improve the accuracy and repeatability of detection result.

Description

Technical Field

[0001] This utility model relates to the field of food testing technology, specifically to a sample pretreatment device for rapid detection of heavy metals in food. Background Technology

[0002] Heavy metal contamination in food is one of the core risk factors affecting food safety. Heavy metals such as lead, cadmium, mercury, and arsenic are cumulative, and long-term intake can cause irreversible damage to the human digestive system, nervous system, and hematopoietic system. Therefore, the detection of heavy metals in food is a core link in food safety supervision.

[0003] In the detection of heavy metals in food, sample pretreatment is a crucial step that determines the accuracy of the test results. Its core purpose is to completely release the heavy metal elements in the sample into the extraction solution and complete solid-liquid separation and matrix purification to obtain a clear test solution that can be used for detection. Currently, the pretreatment steps in pretreatment devices for rapid on-site detection of heavy metals in food are decentralized. The sample homogenization, digestion, filtration, and transfer steps are independent of each other. Operators need to repeatedly transfer samples and extraction solutions between multiple containers, which is not only cumbersome and time-consuming, but also fails to meet the high-efficiency requirements of rapid on-site detection. Furthermore, it can lead to the loss of heavy metal residues on the tube walls during the transfer process, and is also susceptible to cross-contamination from the environment and equipment, directly resulting in a significant decrease in the accuracy and stability of the test results. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a sample pretreatment device for rapid detection of heavy metals in food, which is a fully enclosed, integrated device capable of completing the entire sample pretreatment process in one step.

[0005] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows: a sample pretreatment device for rapid detection of heavy metals in food, comprising a sealed tube body, wherein a homogenization chamber, a sedimentation interception chamber, a membrane filtration chamber, and a quantitative liquid outlet chamber are coaxially connected from top to bottom inside the sealed tube body; a sealing cap is provided at the top opening of the sealed tube body, the sealing cap is provided with a linkage puncture mechanism and a pressure balancing component, the pressure balancing component includes a micro exhaust hole opened on the sealing cap, and an acid and alkali resistant hydrophobic and breathable membrane sealed and fixed inside the exhaust hole, used to balance the internal and external pressure of the device and eliminate flow channel air resistance; a flow guide hole is provided at the bottom of the homogenization chamber, and a composite flow guide component is installed at the flow guide hole, the composite flow guide component including an acid and alkali resistant sealing diaphragm, an annular limiting baffle, and a one-way check valve. The acid and alkali resistant sealing diaphragm completely seals the flow guide hole, which is used to isolate the homogenization chamber and the sedimentation interception chamber during the digestion stage. The annular limiting baffle is set on the inner wall of the downstream side of the flow guide hole. The one-way check valve is fixed below the annular limiting baffle and is used to control the unidirectional flow of liquid from top to bottom. The sedimentation interception chamber is provided with multiple sets of inclined and staggered sedimentation baffles. Each set of sedimentation baffles has several interception micropores, and the pore size of the interception micropores on the multiple sets of sedimentation baffles from top to bottom is arranged in a gradient decreasing manner. The membrane filtration chamber is sealed and snapped together with a glass fiber solid-liquid separation layer, a chelating resin matrix purification layer and a hydrophobic and antibacterial filter membrane layer from top to bottom. The bottom of the quantitative liquid outlet is provided with a capillary liquid outlet, and a flow control valve is installed on the capillary liquid outlet.

[0006] Preferably, the sealing cap and the sealing tube are connected by threads, and an acid and alkali resistant sealing ring is provided between the opening end faces of the sealing cap and the sealing tube. The linkage piercing mechanism includes a piercing needle vertically fixed to the center of the inner wall of the sealing cap. The sealing cap has a pre-tightening position and a conducting position. When the sealing cap is in the pre-tightening position, a safety gap is left between the bottom end of the piercing needle and the acid and alkali resistant sealing diaphragm. When the sealing cap is rotated to the conducting position, the piercing needle moves downward and pierces the acid and alkali resistant sealing diaphragm, thus connecting the flow channels of the homogenization chamber and the sedimentation interception chamber.

[0007] Preferably, the inner wall of the flow guide hole is provided with an annular groove, and the edge of the acid and alkali resistant sealing diaphragm is embedded in the annular groove for heat fusion sealing and fixation. The inner diameter of the annular limiting stop is smaller than the diameter of the flow guide hole, which is used to intercept the fragments generated after the acid and alkali resistant sealing diaphragm is punctured, so as to prevent the fragments from entering the lower chamber.

[0008] Preferably, the bottom of the homogenizing cavity has a tapered opening structure, and the flow guide hole is opened at the center of the tapered opening.

[0009] Preferably, the angle of inclination between the settling baffle and the inner wall of the sealing tube is 30°-60°, the inclination directions of two adjacent sets of settling baffles are opposite and they are arranged in an alternating manner, and the aperture of the intercepting micropores is 80-500 mesh.

[0010] Preferably, the inner wall of the settling interception cavity is provided with an axially extending overflow groove at the corresponding position at the lower end of each set of settling baffles to prevent residue from accumulating and clogging the flow channel.

[0011] Preferably, the inner wall of the membrane filtration chamber is fixedly provided with two sets of upper and lower annular baffles, and a filter layer mounting cavity is formed between the two sets of annular baffles. The glass fiber solid-liquid separation layer, the chelating resin matrix purification layer, and the hydrophobic and antibacterial filter membrane layer are stacked tightly in the filter layer mounting cavity from top to bottom. The annular baffles are provided with a plurality of evenly distributed flow holes, and the pore diameter of the flow holes is smaller than the pore diameter of the filter material of the corresponding side filter layer.

[0012] Preferably, the chelating resin matrix purification layer includes a modified chelating resin filler and a non-woven fabric support layer covering the upper and lower sides of the filler. The edge of the non-woven fabric support layer is provided with an annular sealing lip. The annular sealing lip is interference-fitted with the inner wall of the filter layer mounting cavity to prevent liquid side leakage.

[0013] Preferably, the outer wall of the sealed tube is provided with a capacity scale line corresponding to the position of the quantitative liquid outlet chamber.

[0014] With the above structure, this utility model has the following advantages:

[0015] This invention integrates a homogenization chamber, a sedimentation interception chamber, a membrane filtration chamber, and a quantitative dispensing chamber coaxially from top to bottom within a single sealed tube. This allows the entire process of sample homogenization, closed digestion, gradient sedimentation interception, composite membrane purification and fine filtration, and quantitative dispensing required for heavy metal detection in food to be completed within a sealed chamber. The entire process eliminates the need to open the lid to transfer samples and extracts, preventing the loss of heavy metals due to residual residue on the tube wall caused by transferring from multiple containers. It also avoids cross-contamination from the environment and equipment, improving the accuracy and repeatability of the detection results.

[0016] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is the front view of this utility model.

[0019] Figure 2 yes Figure 1 A schematic diagram of the cross-sectional structure of AA.

[0020] Figure 3 This is a cross-sectional structural diagram of the sealing cap of this utility model.

[0021] As shown in the figure: 1. Sealed tube body; 2. Sealed cap; 3. Capacity scale line; 4. Flow control valve; 5. Miniature vent; 6. Acid and alkali resistant hydrophobic and breathable membrane; 7. Acid and alkali resistant sealing ring; 8. Puncture needle; 9. Guide hole; 10. Acid and alkali resistant sealing diaphragm; 11. Annular limiting baffle; 12. One-way check valve; 13. Settling baffle; 14. Intercepting micropores; 15. Overflow groove; 16. Annular baffle; 17. Flow hole; 18. Glass fiber solid-liquid separation layer; 19. Non-woven fabric support layer; 20. Annular sealing lip; 21. Packing material; 22. Hydrophobic and antibacterial filter membrane layer; 23. Capillary outlet. Detailed Implementation

[0022] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] Combination Figures 1-3As shown, a sample pretreatment device for rapid detection of heavy metals in food includes a sealed tube 1. The sealed tube 1 has a homogenization chamber, a sedimentation interception chamber, a membrane filtration chamber and a quantitative liquid outlet chamber that are coaxially connected from top to bottom inside the sealed tube 1. The four chambers are integrally formed along the axial direction of the sealed tube 1, and the flow channels are coaxially connected without any unnecessary bends or dead corners, thus avoiding sample and extract residues. At the same time, the entire pretreatment process can be completed in a single space.

[0025] Combination Figure 1 and Figure 3 As shown, a sealing cap 2 is provided at the top opening of the sealing tube 1. The sealing cap 2 and the sealing tube 1 are detachably connected by threads. An acid and alkali resistant sealing ring 7 is provided between the sealing cap 2 and the opening end face of the sealing tube 1. The sealing ring can be made of fluororubber or polytetrafluoroethylene. After the sealing cap 2 is tightened, the end face is completely sealed, preventing liquid leakage or external contaminants from entering during the digestion process. The sealing cap 2 is equipped with a linkage puncture mechanism and a pressure balancing component. The pressure balancing component includes a micro exhaust hole 5 opened on the sealing cap 2 and an acid and alkali resistant, hydrophobic and breathable membrane 6 sealed and fixed inside the exhaust hole. The acid and alkali resistant, hydrophobic and breathable membrane 6 is preferably made of polytetrafluoroethylene with a pore size of 0.1-0.45μm. It has the characteristics of being resistant to strong acid and alkali corrosion and being hydrophobic and airtight. It can balance the air pressure inside and outside the device during the digestion process, eliminate air resistance in the flow channel inside the tube, and avoid the tube body deformation caused by excessive internal pressure. It can also prevent the internal digestion liquid from overflowing outward, and at the same time block dust, microorganisms and other pollutants from the external environment from entering the tube, ensuring the cleanliness of the pretreatment process.

[0026] The linkage piercing mechanism includes a piercing needle 8 vertically fixed to the center of the inner wall of the sealing cap 2. The tip of the piercing needle 8 preferably adopts a triangular or conical structure, possessing sufficient structural strength to smoothly pierce the sealing diaphragm without generating excessive debris. The sealing cap 2 has two working positions through threaded engagement: a pre-tightening position and a conducting position. When the sealing cap 2 is in the pre-tightening position, a safe gap is left between the bottom end of the piercing needle 8 and the acid and alkali resistant sealing diaphragm 10 below. At this time, the diaphragm remains intact and can completely isolate the upper and lower chambers. When the sealing cap 2 is screwed to the conducting position, the sealing cap 2 undergoes axial displacement downward along the thread, synchronously driving the piercing needle 8 to move downward, piercing the acid and alkali resistant sealing diaphragm 10 with its tip. Then, the sealing cap 2 is screwed back to the pre-tightening position, thereby opening the flow channels between the homogenization chamber and the sedimentation interception chamber, realizing the downward flow of the extract after digestion.

[0027] Combination Figure 2As shown, the homogenization chamber is the core chamber for sample homogenization and sealed digestion. The chamber volume can be designed from 10-50 mL according to the routine sampling volume for food testing, adapting to the routine sampling needs of on-site rapid testing. The bottom of the homogenization chamber has a conical constriction structure, with the cone angle set to 30°-60° to facilitate complete collection and diversion of the digested extract, eliminating liquid residue dead zones. The diversion hole 9 is located at the center of the conical constriction, ensuring that all collected liquid flows downwards. A composite diversion component is installed at the diversion hole 9, including an acid and alkali resistant sealing diaphragm 10, an annular limiting baffle 11, and a one-way check valve 12. The inner wall of the flow guide hole 9 has an annular groove. The edge of the acid and alkali resistant sealing diaphragm 10 is embedded in the annular groove and completely fixed by heat fusion sealing. This completely seals the flow guide hole 9, effectively isolating the homogenization chamber and the sedimentation interception chamber during the digestion stage. This ensures that the digestion process is completed in a completely sealed homogenization chamber, preventing the sample from entering the lower chamber prematurely and affecting the digestion effect. The acid and alkali resistant sealing diaphragm 10 is preferably made of polytetrafluoroethylene (PTFE) with a thickness of 0.1-0.3 mm, possessing both good sealing properties and easy puncture resistance, adapting to the operational requirements of the linkage puncture mechanism. The annular limiting baffle 11 is located on the inner wall downstream of the flow guide hole 9 and is integrally formed with the inner wall of the sealing tube 1. The inner diameter of the annular limiting baffle 11 is smaller than the diameter of the flow guide hole 9. On the one hand, it can intercept the fragments generated after the acid and alkali resistant sealing diaphragm 10 is punctured, preventing the fragments from entering the lower chamber and causing blockage of the flow channel or filter layer. On the other hand, it can provide stable installation support for the one-way check valve 12. The one-way check valve 12 is fixed below the annular limiting stop 11. A duckbill type one-way check valve 12 with acid and alkali resistance is preferred. It can control the liquid to flow only from top to bottom in one direction, avoid the liquid and residue in the lower chamber from flowing back to the homogenization chamber, prevent the separated solid residue from re-contaminating the filtrate, and ensure the stability of the pretreatment effect.

[0028] The sedimentation interception chamber is located downstream of the homogenization chamber and is used for gradient sedimentation and coarse filtration of the digested extract to remove large solid particles from the sample. The sedimentation interception chamber is equipped with multiple sets of inclined, staggered sedimentation baffles 13, with 3-5 sets of baffles 13. The angle between the sedimentation baffles 13 and the inner wall of the sealed tube 1 is 30°-60°. Adjacent sets of sedimentation baffles 13 have opposite inclination directions and are staggered, forming a baffle-like flow channel within the chamber. This significantly extends the flow path of the extract, allowing solid residues in the liquid to settle fully under gravity and baffle resistance, thus improving the solid-liquid separation effect. Each set of settling baffles 13 has several evenly distributed interception micropores 14. The pore size of the interception micropores 14 on the multiple sets of settling baffles 13 from top to bottom is set in a gradient decreasing manner. The pore size range of the interception micropores 14 is 80-500 mesh. For example, the pore size of the uppermost settling baffle 13 is 80-100 mesh, the middle layers are 150-200 mesh, 250-300 mesh, and the pore size of the lowermost settling baffle 13 is 400-500 mesh. Through the design of the gradually decreasing pore size, sample residues of different particle sizes are intercepted in sequence, avoiding large particles from directly entering the lower filter layer and causing filter layer blockage, extending the service life of the device, and ensuring smooth flow. An axially extending overflow channel 15 is provided on the inner wall of the settling interception chamber at the corresponding position at the lower end of each set of settling baffles 13. When too much residue accumulates on the settling baffles 13 and the micropores of the baffles are partially blocked, the liquid can flow downstream through the overflow channel 15 to avoid complete blockage of the flow channel and ensure that the pretreatment process can be completed smoothly.

[0029] The membrane filtration chamber, located downstream of the sedimentation interception chamber, is used for deep purification and precision filtration of the coarsely filtered extract to obtain a clear test solution that meets the testing requirements. Two sets of annular baffles 16 are fixedly installed on the inner wall of the membrane filtration chamber. These two sets of annular baffles 16 are integrally formed with the inner wall of the sealing tube 1, forming a filter layer mounting cavity between them. The glass fiber solid-liquid separation layer 18, the chelating resin matrix purification layer, and the hydrophobic and antibacterial filter membrane layer 22 are tightly stacked sequentially from top to bottom within the filter layer mounting cavity, with no gaps between layers to prevent side leakage. Several evenly distributed flow holes 17 are provided on both sets of annular baffles 16. The diameter of the flow holes 17 is smaller than the pore size of the filter media in the corresponding side filter layer. This ensures that the liquid flows evenly across the entire filter layer cross-section, preventing localized overflow from affecting the purification and filtration effect, and also provides stable positioning and support for each filter layer, preventing deformation and damage to the filter media under liquid impact.

[0030] The glass fiber solid-liquid separation layer 18 uses glass fiber filter material with a pore size of 1-5μm, which can efficiently intercept micron-sized fine solid particles that are not completely removed in the sedimentation interception chamber, forming a protective layer for the next stage of purification, preventing fine particles from clogging the gaps in the resin filler 21, and ensuring the stability of the purification effect. The chelating resin matrix purification layer includes a modified chelating resin filler 21 and a non-woven fabric support layer 19 covering the upper and lower sides of the filler 21. The modified chelating resin filler 21 preferably uses an iminodiacetic acid type chelating resin optimized for food matrices, which can specifically adsorb matrix interferences such as oils, proteins, and organic acids in the food extract, while not adsorbing heavy metal ions such as lead, cadmium, mercury, and arsenic. While purifying the matrix, it ensures the recovery rate of the analytes and eliminates the interference of matrix effects on subsequent detection results. The non-woven fabric support layer 19 is made of acid and alkali resistant polypropylene non-woven fabric, which can uniformly support and fix the filler 21, preventing the filler 21 from leaking out, and ensuring that the liquid flows evenly through the filler 21 layer. The edge of the non-woven fabric support layer 19 is provided with an annular sealing lip 20, which is interference-fitted with the inner wall of the filter layer installation cavity. The interference amount can be set to 0.1-0.2mm, which can prevent liquid from leaking from the side of the filter layer and ensure that all extracts flow through the filler 21 layer to complete matrix purification, ensuring the consistency of purification effect. The hydrophobic and antibacterial filter membrane layer 22 is made of polytetrafluoroethylene hydrophobic filter membrane with a pore size of 0.22-0.45μm. It can perform final precision filtration of the extract to remove residual micro-impurities and microorganisms, and obtain a clear and transparent test solution that can be directly used for instrument detection.

[0031] The quantitative dispensing chamber is located at the downstream end of the membrane filtration chamber and is used to collect the purified and filtered test solution and achieve quantitative dispensing. A volume scale 3 is set on the outer wall of the sealed tube 1 corresponding to the position of the quantitative dispensing chamber. The accuracy of the scale can be set to 0.1 mL, adapting to the quantitative sampling needs of on-site rapid testing. Operators can intuitively and accurately read the volume of the test solution in the chamber. A capillary outlet 23 is set at the bottom of the quantitative dispensing chamber. The inner diameter of the capillary outlet 23 is 0.5-1 mm, which allows for slow and stable liquid outflow, facilitating precise control of the dispensing volume and avoiding waste of the test solution. A flow control valve 4 is installed on the capillary outlet 23. The flow control valve 4 adopts a micro-stop valve structure resistant to acid and alkali corrosion, which can precisely control the on / off state and flow rate of the dispensing, meeting the operational requirements of quantitative sampling.

[0032] The complete working process and usage method of the sample pretreatment device for rapid detection of heavy metals in food according to this embodiment are as follows:

[0033] Sample pretreatment preparation: Unscrew the sealing cap 2 from the sealing tube 1, add the food sample to be tested, digestion reagent and extraction reagent to the homogenization chamber. The food sample can be pre-cut and homogenized. Weigh 0.5-5g according to the testing standard requirements and put it into the homogenization chamber. Then add the digestion reagent and extraction reagent commonly used for heavy metal detection in food, such as dilute nitric acid solution, hydrogen peroxide solution, etc., to meet the heavy metal extraction requirements of different types of food.

[0034] Closed homogenization and digestion: Screw the sealing cap 2 to the pre-tightened position. At this time, a safe gap is left between the bottom end of the puncture needle 8 and the acid and alkali resistant sealing diaphragm 10. The acid and alkali resistant sealing diaphragm 10 remains intact, and the homogenization chamber is completely isolated from the lower chamber, forming an independent closed digestion space. The sealing cap 2 and the tube body are completely sealed by the acid and alkali resistant sealing ring 7. Then, the sample in the homogenization chamber can be homogenized and digested by manual shaking or with a portable handheld homogenizer, so that the sample tissue is completely broken down and the heavy metal elements in the sample are fully released into the extract. The gas generated during the digestion process can be discharged through the air pressure balance component on the sealing cap 2 to balance the air pressure inside and outside the tube and avoid excessive internal pressure. At the same time, the acid and alkali resistant hydrophobic and breathable membrane 6 can prevent the internal liquid from overflowing and also block the entry of external contaminants, ensuring the safety and cleanliness of the digestion process.

[0035] Flow channel opening and gradient sedimentation interception: After the sample digestion is completed, the sealing cap 2 is tightened from the pre-tightening position to the opening position. The sealing cap 2 is axially displaced downward along the thread, which simultaneously drives the piercing needle 8 to move downward. The needle tip pierces the acid and alkali resistant sealing diaphragm 10, opening the flow channel between the homogenization chamber and the sedimentation interception chamber. The device is kept in a vertical static state. The digestion extract in the homogenization chamber flows out through the guide hole 9 under the action of gravity, and enters the sedimentation interception chamber through the inner hole of the annular limiting baffle 11 and the one-way check valve 12. After the extract enters the sedimentation interception chamber, it flows downward along the baffle-like flow channel formed by the staggered inclined sedimentation baffles 13. Large particles of sample residue are first intercepted by the large-diameter interception micropores 14 of the upper sedimentation baffle 13, and smaller particles of residue are successively intercepted by the lower-level interception micropores 14 with decreasing pore size. Under the action of gravity, the solid residue accumulates at the lower end of the sedimentation baffle 13. When the accumulation of residue causes partial blockage of the micropores, the liquid can continue to flow downward through the overflow groove 15 corresponding to the lower end of the baffle, avoiding blockage of the flow channel, completing the initial solid-liquid separation and gradient sedimentation interception of the extract, and significantly reducing the filtration load of the lower filter layer.

[0036] Composite purification and precision filtration: After sedimentation and interception, the extract enters the membrane filtration chamber from top to bottom under the action of gravity. First, it flows through the glass fiber solid-liquid separation layer 18, which intercepts the micron-sized fine solid particles that were not removed in the sedimentation interception chamber, completing the secondary solid-liquid separation. Then, the extract flows through the chelating resin matrix purification layer, where food matrix interfering substances such as oils, proteins, and organic acids in the solution are specifically adsorbed and removed by the modified chelating resin filler 21, while the heavy metal ions to be tested are completely retained in the solution, completing matrix purification and eliminating the interference of matrix effect on subsequent detection results. Finally, the extract flows through the hydrophobic and antibacterial filter membrane layer 22, completing the final precision filtration, removing residual micro-impurities and microorganisms in the solution, and obtaining a clear, interference-free test solution that can be directly used for detection.

[0037] Quantitative Dispensing and Detection Applications: After composite purification and filtration, the test solution flows entirely into the quantitative dispensing chamber under gravity. Operators can accurately read the volume of the test solution within the chamber using the volume scale 3 on the outer wall. When collecting the test solution, the flow control valve 4 at the capillary outlet 23 is slowly opened, allowing for slow and controllable dispensing through the capillary. The required volume of test solution can then be directly used for analysis with test strips, atomic fluorescence spectrometers, ultraviolet spectrophotometers, and rapid heavy metal detectors in food. Throughout the operation, the one-way check valve 12 prevents liquid and residue from flowing back into the homogenization chamber from the lower chamber, avoiding recontamination of the filtrate by separated solid residue and ensuring the cleanliness of the test solution and the accuracy of the test results.

[0038] This embodiment presents a sample pretreatment device for rapid detection of heavy metals in food. By coaxially integrating a homogenization chamber, sedimentation interception chamber, membrane filtration chamber, and quantitative dispensing chamber from top to bottom within a single sealed tube 1, the entire process required for heavy metal detection—sample homogenization, closed digestion, gradient sedimentation interception, composite membrane purification and fine filtration, and quantitative dispensing—is completed within a sealed chamber. The entire process eliminates the need to open the lid to transfer samples and extracts, fundamentally preventing the loss of heavy metals due to residual residue on the tube wall caused by multiple container transfers. It also avoids cross-contamination from the environment and equipment, significantly improving the accuracy and repeatability of the detection results. Furthermore, the device achieves solid-liquid separation and matrix purification in one step through the combination of gradient sedimentation interception and multi-stage composite filtration purification, greatly simplifying the operation steps for rapid on-site testing, shortening pretreatment time, and featuring a compact overall structure that eliminates the need for large supporting equipment, making it suitable for various application scenarios such as laboratories and on-site sampling inspections.

[0039] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown throughout the text are only one of the embodiments of the present invention. The actual structure is not limited to this. In conclusion, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the inventive spirit of the present invention, such design should fall within the protection scope of the present invention.

Claims

1. A sample pretreatment device for rapid detection of heavy metals in food, characterized in that: The tube includes a sealed tube body, and the interior of the sealed tube body is coaxially connected from top to bottom to include a homogenization chamber, a sedimentation interception chamber, a membrane filtration chamber and a quantitative liquid outlet chamber; A sealing cap is provided at the top opening of the sealing tube. The sealing cap is equipped with a linkage puncture mechanism and a pressure balancing component. The pressure balancing component includes a micro exhaust hole opened on the sealing cap and an acid and alkali resistant, hydrophobic and breathable membrane sealed and fixed inside the exhaust hole, which is used to balance the internal and external pressure of the device and eliminate air resistance in the flow channel. The bottom of the homogenization chamber is provided with a flow guide hole, and a composite flow guide assembly is installed at the flow guide hole. The composite flow guide assembly includes an acid and alkali resistant sealing diaphragm, an annular limiting baffle, and a one-way check valve. The acid and alkali resistant sealing diaphragm completely blocks the flow guide hole and is used to isolate the homogenization chamber from the sedimentation interception chamber during the digestion stage. The annular limiting baffle is set on the inner wall of the downstream side of the flow guide hole, and the one-way check valve is fixed below the annular limiting baffle and is used to control the unidirectional flow of liquid from top to bottom. The settling interception chamber is equipped with multiple sets of inclined and staggered settling baffles. Each set of settling baffles is provided with several interception micro-holes, and the diameter of the interception micro-holes on the multiple sets of settling baffles from top to bottom is arranged in a gradient decreasing manner. The membrane filtration chamber is sealed and snapped together from top to bottom with a glass fiber solid-liquid separation layer, a chelating resin matrix purification layer and a hydrophobic antibacterial filter membrane layer. The bottom of the quantitative liquid outlet chamber is provided with a capillary outlet, and a flow control valve is installed on the capillary outlet.

2. The sample pretreatment device for rapid detection of heavy metals in food according to claim 1, characterized in that: The sealing cap and the sealing tube are connected by threads. An acid and alkali resistant sealing ring is provided between the opening end faces of the sealing cap and the sealing tube. The linkage piercing mechanism includes a piercing needle that is vertically fixed to the center of the inner wall of the sealing cap. The sealing cap has a pre-tightening position and a conducting position. When the sealing cap is in the pre-tightening position, a safety gap is left between the bottom end of the piercing needle and the acid and alkali resistant sealing diaphragm. When the sealing cap is rotated to the conducting position, the piercing needle moves downward and pierces the acid and alkali resistant sealing diaphragm, thus connecting the flow channels of the homogenization chamber and the sedimentation interception chamber.

3. The sample pretreatment device for rapid detection of heavy metals in food according to claim 1, characterized in that: The inner wall of the flow guide hole is provided with an annular groove. The edge of the acid and alkali resistant sealing diaphragm is embedded in the annular groove and heat-sealed. The inner diameter of the annular limiting stop is smaller than the diameter of the flow guide hole, which is used to intercept the fragments generated after the acid and alkali resistant sealing diaphragm is punctured, and to prevent the fragments from entering the lower chamber.

4. The sample pretreatment device for rapid detection of heavy metals in food according to claim 1, characterized in that: The bottom of the homogenizing cavity has a tapered opening structure, and the flow guide hole is opened at the center of the tapered opening.

5. The sample pretreatment device for rapid detection of heavy metals in food according to claim 1, characterized in that: The angle between the settling baffle and the inner wall of the sealing tube is 30°-60°. The inclination directions of two adjacent sets of settling baffles are opposite, and they are arranged in an alternating and staggered manner. The diameter of the intercepting micropores is 80-500 mesh.

6. The sample pretreatment device for rapid detection of heavy metals in food according to claim 1, characterized in that: An axially extending overflow groove is provided on the inner wall of the settling interception chamber at the corresponding position at the lower end of each set of settling baffles to prevent residue from accumulating and clogging the flow channel.

7. The sample pretreatment device for rapid detection of heavy metals in food according to claim 1, characterized in that: The inner wall of the membrane filtration chamber is fixedly provided with two sets of upper and lower annular baffles, and a filter layer mounting cavity is formed between the two sets of annular baffles. The glass fiber solid-liquid separation layer, the chelating resin matrix purification layer, and the hydrophobic and antibacterial filter membrane layer are stacked tightly in the filter layer mounting cavity from top to bottom. The annular baffles are provided with a number of evenly distributed flow holes, and the diameter of the flow holes is smaller than the pore diameter of the filter material of the corresponding side filter layer.

8. The sample pretreatment device for rapid detection of heavy metals in food according to claim 7, characterized in that: The chelating resin matrix purification layer includes a modified chelating resin filler and a non-woven fabric support layer covering the upper and lower sides of the filler. The edge of the non-woven fabric support layer is provided with an annular sealing lip. The annular sealing lip is interference-fitted with the inner wall of the filter layer mounting cavity to prevent liquid side leakage.

9. The sample pretreatment device for rapid detection of heavy metals in food according to claim 1, characterized in that: The outer wall of the sealed tube is provided with a capacity scale line corresponding to the position of the quantitative liquid outlet chamber.

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