Pesticide residue extraction and detection device

Abstract

The invention discloses a pesticide residue extraction and detection device and relates to the field of pesticide residue detection.The pesticide residue extraction and detection device comprises a detection column box, a sample injection mechanism and a gas circuit mechanism, the sample injection mechanism comprises a test tube rack, a sample test tube and a sample injection column, the sample test tube is inversely arranged on the test tube rack, a test tube cover is arranged at an opening of the sample test tube, and a sample injection small hole is formed in the test tube cover; a small sample injection hole is formed in the sample test tube, a hole plug is arranged in the small sample injection hole in an interference manner, the sample injection column is rotatably mounted at the top of the detection column box, a micro sample injector is mounted in the sample injection column, a vaporizing chamber is arranged in the detection column box, a sample injection tube communicated with the vaporizing chamber is arranged on the detection column box, and the micro sample injector extracts a liquid sample in the sample test tube through rotation and then injects the liquid sample into the sample injection tube. The gas path mechanism comprises a carrier gas bottle and a gas conveying pipe connected with the carrier gas bottle, and the gas conveying pipe is communicated with the vaporizing chamber, so that the problem that a solution is hung on the wall and remains due to a traditional upright test tube is avoided, the defect that a traditional inclined section needle is not thorough in sampling is overcome, sampling errors are greatly reduced, and the accuracy of quantitative analysis of pesticide residues is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of pesticide residue detection, specifically to a pesticide residue extraction and detection device. Background Technology

[0002] Pesticide residue detection is a crucial aspect of food safety monitoring. Gas chromatography (GC) is widely used for the quantitative analysis of pesticide residues in vegetables and other agricultural products due to its high accuracy and good separation performance. The sample introduction and vaporization effects directly determine the accuracy and stability of pesticide residue detection. However, existing pesticide residue extraction and detection devices have significant technical shortcomings in practical applications: There are two overlapping problems regarding injection accuracy: First, although the sample solution is filtered during preparation, for agricultural products with high fiber content such as vegetables, the extract still contains a large number of fine fibers that are difficult to completely filter out. These fibers easily adhere to the inner wall of the sample tube. During injection, as the solution volume in the tube decreases, the fibers carry some sample solution and remain on the wall, preventing effective absorption and directly reducing injection accuracy. Second, existing microsyringes mostly use inclined needles with inclined sampling holes, which cannot fit tightly to the bottom of the tube, making it difficult to completely absorb the sample solution and leaving solution residue. These two problems overlap, further amplifying injection errors and seriously affecting the accuracy of pesticide residue detection results. Simultaneously, when the mixed fibers enter the vaporization chamber with the sample, some fibers vaporize, interfering with the detection signal, while unvaporized fibers enter the gas chromatography column. Long-term use can easily cause column blockage, reducing equipment lifespan and detection stability.

[0003] There are also significant shortcomings in sample vaporization: existing detection devices mostly use micro-injectors to inject the sample solution into the vaporization chamber at one time. The injection is concentrated and the injection volume is relatively large. The sample cannot be fully vaporized instantly and cannot be quickly and completely carried into the chromatographic column by the carrier gas. This leads to problems such as peak expansion and peak tailing, which greatly reduces the detection accuracy and the reliability of the results.

[0004] In summary, existing pesticide residue extraction and detection devices suffer from low injection accuracy due to fiber adhesion and sample residue, and incomplete vaporization due to single-shot injection. These devices fail to meet the requirements for high-precision and stable pesticide residue detection. Therefore, there is an urgent need for a pesticide residue extraction and detection device that can improve injection accuracy, achieve complete sample vaporization, and prevent column blockage. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a pesticide residue extraction and detection device to solve the problems of low sample injection accuracy and incomplete gasification.

[0006] The objective of this invention is achieved through the following technical solution: a pesticide residue extraction and detection device, comprising a detection column box, a sample injection mechanism, and a gas path mechanism. The sample injection mechanism includes a test tube rack, a sample test tube, and an injection column. The sample test tube is inverted on the test tube rack, and the opening of the sample test tube is provided with a test tube cap. The test tube cap has a small injection hole, and a plug is interference-fitted into the injection hole. The injection column is rotatably mounted on the top of the detection column box, and a micro-injector is installed inside the injection column. A vaporization chamber is provided inside the detection column box, and an injection tube communicating with the vaporization chamber is provided on the detection column box. The micro-injector extracts the liquid sample from the sample test tube by rotation and then injects it into the injection tube. The gas path mechanism includes a carrier gas cylinder and a gas delivery pipe connected to the carrier gas cylinder, and the gas delivery pipe communicates with the vaporization chamber.

[0007] Furthermore, a micro-pressure injection tube is fixedly inserted through the side wall of the vaporization chamber. A piston is slidably fitted inside the micro-pressure injection tube. The end of the piston away from the vaporization chamber is connected to a piston rod. The piston rod is connected to the telescopic shaft of an electric push rod. The cylinder of the electric push rod is installed inside the detection column box. The injection tube is connected to the side wall of the micro-pressure injection tube. A vaporization tube is horizontally installed inside the vaporization chamber. An electric heating tube is threaded around the vaporization tube. The middle part of the vaporization tube is connected to a gas chromatography column. The micro-pressure injection tube and the gas delivery tube are respectively connected to the two ends of the vaporization tube.

[0008] Furthermore, a vaporization chamber is formed inside the vaporization tube, and multiple pressurization holes communicating with the vaporization chamber are opened at both ends of the vaporization tube, with the multiple pressurization holes at both ends of the vaporization tube arranged opposite to each other.

[0009] Furthermore, the test tube rack includes a base, a chassis, a central limiting plate, and a top plate. The chassis is rotatably mounted on the top of the base, and a mounting shaft is coaxially fixed to the top of the chassis. The central limiting plate is coaxially sleeved on the mounting shaft, and the top plate is detachably connected to the mounting shaft. The chassis has multiple first through holes extending along its circumference. The central limiting plate has second through holes at positions corresponding to the first through holes. The bottom of the top plate has a groove at positions corresponding to the second through holes. The test tube cap is threaded onto the sample test tube. The diameter of the second through hole is larger than the diameter of the test tube cap, and the diameter of the test tube cap is larger than the diameter of the first through hole. The bottom of the sample test tube is fitted into the groove.

[0010] Furthermore, a positioning post is fixed to the top of the mounting shaft, a threaded shaft is fixed to the top of the positioning post, a positioning groove is provided at the bottom of the top plate, the cross-section of the positioning groove and the cross-section of the positioning post are both rectangular, a third through hole is provided at the top of the top plate communicating with the positioning groove, the positioning post is adapted to fit in the positioning groove, and the threaded shaft passes through the third through hole and is threaded to connect to the mounting cap.

[0011] Furthermore, a drive spindle is rotatably mounted on the top of the base, and a motor is installed inside the base. The output shaft of the motor is connected to the drive spindle via a coupling. A micro-vibration base is fixed on the top of the drive spindle. A rectangular insertion port is opened on the top of the micro-vibration base. A rectangular insertion block is fixed on the bottom of the chassis. The rectangular insertion block is fitted with the rectangular insertion port with clearance. A spring hole is opened on the inner side wall of the rectangular insertion port. A spring is installed in the spring hole and contacts the rectangular insertion block. A fourth through hole is opened through the rectangular insertion block along the axial direction of the spring hole. A small-diameter through hole communicating with the spring hole and a threaded hole coaxial with the spring hole are opened on the outer side wall of the micro-vibration base. The tail of the screw passes through the small-diameter through hole and the fourth through hole and is threaded into the threaded hole.

[0012] Furthermore, one end of the test tube cap is provided with an internal threaded hole, and a flow guide cone hole is provided inside the test tube cap. The large-diameter end of the flow guide cone hole is connected to the internal threaded hole, and the small-diameter end of the flow guide cone hole is connected to the sample inlet hole.

[0013] Furthermore, a microfiltration membrane is disposed inside the flow guide cone orifice.

[0014] Furthermore, the injection mechanism also includes an injector mounting bracket, an injection spindle is horizontally fixed to the side wall of the injection column, the injection spindle is rotatably mounted on the injector mounting bracket, an injection motor is mounted on the injector mounting bracket, the output shaft of the injection motor is driven and connected to the injection spindle, the tube body of the micro-injector is fixed on the injection column, an injection electric push rod is installed inside the injection column, the injection electric push rod is parallel to the micro-injector, the telescopic shaft of the injection electric push rod is connected to the piston injection rod of the micro-injector, and the head of the micro-injector protrudes from one end of the injection column.

[0015] Furthermore, the bottom of the injector mounting bracket is slidably inserted into the detection column box, and a lifting electric push rod is vertically installed inside the detection column box. The telescopic shaft of the lifting electric push rod moves out of the detection column box and connects to the injector mounting bracket.

[0016] The beneficial effects of this invention are: 1. The sample tube is designed to be inverted, and the inner cap has a conical flow-guiding hole structure. This allows the sample solution to flow towards the injection hole by gravity, completely avoiding the problem of solution residue on the walls caused by fiber adhesion and liquid level drop in traditional upright test tubes. At the same time, the micro-syringe can accurately sample from the bottom of the test tube through the injection hole, solving the problem of incomplete sampling by traditional inclined needles. This double elimination of injection residue significantly reduces injection error and ensures the accuracy of quantitative analysis of pesticide residues.

[0017] 2. A microfiltration membrane is added inside the test tube cap, which can accurately filter the fine fibers remaining in the sample extract before injection. This prevents fibers from entering the vaporization chamber and interfering with the detection signal, causing data distortion, and also avoids unvaporized fibers from entering the gas chromatography column and causing blockage. This significantly extends the service life of the chromatography column and detection equipment and improves the long-term stability of the detection process.

[0018] 3. Abandoning the traditional one-time centralized sample injection method, a micro-pressure injection tube is used in conjunction with a piston to inject small doses of sample under pressure into the vaporization chamber. Combined with the uniform heating of the electric heating tube with external threads, the sample is instantly and fully vaporized, fundamentally solving the problems of chromatographic peak expansion and peak tailing caused by traditional injection methods, and significantly improving detection accuracy and result reliability.

[0019] 4. The vaporization tube has opposing pressure holes at both ends, which allows the carrier gas and the vaporized sample gas to mix in opposite directions. On the one hand, the carrier gas disperses the sample solution, making it easier for the dispersed sample to vaporize instantly. On the other hand, it ensures that the vaporized sample is carried into the chromatographic column quickly and uniformly by the carrier gas, further optimizing the peak shape, improving the detection response speed, and meeting the high-precision requirements of pesticide residue trace detection. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the pesticide residue extraction and detection device of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the structure of the pesticide residue extraction and detection device of the present invention. Figure 2 ; Figure 3 This is a schematic diagram of the internal structure of the detection column box in the pesticide residue extraction and detection device of the present invention; Figure 4 for Figure 3 Enlarged view of point A in the middle; Figure 5 This is a schematic diagram of the sample tube structure in the pesticide residue extraction and detection device of the present invention; Figure 6 This is a schematic diagram of the internal structure of the injection column in the pesticide residue extraction and detection device of the present invention; Figure 7 This is a schematic diagram of the test tube rack in the pesticide residue extraction and detection device of the present invention; Figure 8 This is a schematic diagram of the internal structure of the crushing chamber in the pesticide residue extraction and detection device of the present invention; Figure 9 This is a schematic diagram of the structure of the grinding ring in the pesticide residue extraction and detection device of the present invention; Figure 10 This is a schematic diagram of the oscillation device in the pesticide residue extraction and detection device of the present invention; In the diagram, 1-detection column box, 2-test tube rack, 3-sample test tube, 4-injection column, 5-test tube cap, 6-injection orifice, 7-orifice plug, 8-microsyringe, 9-vaporization chamber, 10-injection tube, 11-carrier gas bottle, 12-gas delivery tube, 13-vaporization tube, 14-micro-pressure injection tube, 15-piston, 16-piston rod, 17-electric push rod, 18-electric heating tube, 19-gas chromatography column, 20-vaporization chamber, 21-pressure orifice, 22-base, 23-base plate, 24-central limiting plate, 25-top plate, 26-mounting shaft, 27-first through hole, 28-second through hole, 29-groove, 30-positioning column, 31-threaded shaft, 32-positioning groove, 33-third through hole, 34-mounting cap, 35-micro-vibration base, 36-rectangular socket, 37 - Rectangular insert, 38- Spring hole, 39- Spring, 40- Small diameter through hole, 41- Threaded hole, 42- Screw, 43- Guide cone hole, 44- Microfiltration membrane, 45- Sampler mounting bracket, 47- Sampler motor, 48- Sampler electric push rod, 49- Lifting electric push rod, 50- Crushing chamber, 51- Processing chamber, 52- Crushing cone, 53- Crushing main shaft, 54- Spiral blade, 55- Crushing motor, 56- Feed inlet, 57- Fixed grinding ring, 58- Moving grinding ring, 59- Long blade, 60- Short blade, 61- Oscillating base, 62- Oscillating main shaft, 63- Oscillating secondary shaft, 64- First C-clamp, 65- Second C-clamp, 66- Test tube mounting column, 67- First hinge shaft, 68- First mounting plate, 69- Second hinge shaft, 70- Second mounting plate. Detailed Implementation

[0021] Example 1 like Figures 1 to 10As shown, the pesticide residue extraction and detection device includes a detection column box 1, a sample injection mechanism, and a gas path mechanism. The sample injection mechanism includes a test tube rack 2, a sample test tube 3, and an injection column 4. The sample test tube 3 is inverted on the test tube rack 2, and the opening of the sample test tube 3 is provided with a test tube cap 5. The test tube cap 5 has a small injection hole 6, and a plug 7 is interference-fitted into the injection hole 6. The injection column 4 is rotatably mounted on the top of the detection column box 1, and a micro-injector 8 is installed inside the injection column 4. A vaporization chamber 9 is provided inside the detection column box 1, and an inlet valve communicating with the vaporization chamber 9 is provided on the detection column box 1. The sample tube 10 and the micro-syringe 8 extract the liquid sample from the sample tube 3 by rotation and then inject it into the sample tube 10. The gas path mechanism includes a carrier gas bottle 11 and a gas delivery tube 12 connected to the carrier gas bottle 11. The gas delivery tube 12 is connected to the vaporization chamber 9. The agricultural product for which pesticide residue testing is required is prepared into a sample solution. A standard amount of sample solution is injected into the sample tube 3. Then, the test tube cap 5 is installed on the mouth of the sample tube 3 to seal it. Next, the sample tube 3 is placed upside down on the test tube rack 2, and the sample solution is completely vaporized by gravity. The sample solution flows out through the injection orifice 6 to prevent it from accumulating at the bottom of the sample tube 3. The plug 7, made of butyl rubber, prevents the sample solution from flowing out before injection. The injection column 4 is rotated 180° so that the needle of the microsyringe 8 faces upwards, aligning with the injection orifice 6. The needle of the microsyringe 8 pierces the plug 7 and enters the injection orifice 6. Combined with the gravity of the sample solution, the microsyringe 8 completely extracts the sample solution from the sample tube 3, minimizing sample solution loss. Within the allowable error range, the injection column 4 is then rotated so that the micro-injector 8 corresponds to the injection tube 10. The top opening of the injection tube 10 is fitted with a tube stopper made of butyl rubber. The needle of the micro-injector 8 pierces the tube stopper, thereby injecting the sample solution in the micro-injector 8 into the injection tube 10. The sample solution is then guided to the vaporization chamber 9 through the injection tube 10. This solves the defect of incomplete sampling by traditional inclined section needles, eliminates injection residues, significantly reduces injection errors, and ensures the accuracy of quantitative analysis of pesticide residues.

[0022] Example 2 Based on Example 1, such as Figure 1 , Figure 8 and Figure 9As shown, when conducting pesticide residue testing on agricultural products, the products need to be pre-treated using a sample extraction system to prepare a sample solution. This sample extraction system includes a crushing and grinding integrated machine, which comprises a crushing chamber 50. A processing chamber 51 is formed at the bottom of the crushing chamber 50 along its height. Within the processing chamber 51, a crushing mechanism and a grinding mechanism are arranged sequentially from top to bottom. The crushing mechanism includes a crushing cone 52 and a crushing spindle 53. The crushing spindle 53 is rotatably mounted on the crushing chamber 50 and is vertically oriented. The crushing cone 52 is fixedly fitted onto the crushing spindle 53, and its diameter gradually increases from top to bottom. A spiral blade is fitted onto the crushing cone 52. The material feeding gap between the spiral blade 54 and the processing chamber 51 gradually decreases from top to bottom. A crushing motor 55 is installed on the top of the crushing box 50. The output shaft of the crushing motor 55 is connected to the crushing spindle 53. Multiple feed inlets 56 connected to the processing chamber 51 are opened on the top of the crushing box 50 along its own circumference. Agricultural products to be tested for pesticide residues are fed into the processing chamber 51 through the feed inlets 56. The agricultural products are first crushed by the crushing mechanism. The crushing motor 55 drives the crushing cone 52 to rotate through the crushing spindle 53. The crushing cone 52 drives the spiral blade 54 on it to rotate, so that the agricultural products enter the grinding mechanism through the material feeding gap under their own gravity. The size of the grinding ring gradually decreases from top to bottom, causing the agricultural products to be gradually broken into smaller pieces. Agricultural products that meet the grinding requirements enter the grinding mechanism for grinding. The grinding mechanism includes a fixed grinding ring 57 and a moving grinding ring 58. The outer wall of the fixed grinding ring 57 is fixed to the inner wall of the processing chamber 51. The moving grinding ring 58 is fixedly mounted on the crushing main shaft 53. Several long blades 59 and several short blades 60 are fixed along the circumference of the inner wall of the fixed grinding ring 57. The short blades 60 are connected below the long blades 59. The upper grinding gap between the long blades 59 and the moving grinding ring 58 gradually decreases from top to bottom, and the lower grinding gap between the short blades 60 and the moving grinding ring 58 gradually decreases from top to bottom. The minimum lower grinding gap... The larger size is equal to or smaller than the minimum size of the upper grinding gap, and the taper formed by the upper grinding gap is smaller than the taper formed by the lower grinding gap. This allows the crushed agricultural products to be gradually ground between the fixed grinding ring 57 and the moving grinding ring 58. The crushing main shaft 53 simultaneously rotates the moving grinding ring 58, and the outer wall of the moving grinding ring 58 is treated with friction. This allows the agricultural products to be initially ground between the long blade 59 and the moving grinding ring 58, and then fall between the short blade 60 and the moving grinding ring 58 for fine grinding. This fully pulverizes the agricultural products, ensuring that when acetonitrile extract is added later, pesticides that have penetrated into the pulp of the agricultural products can be completely separated from fats, pigments, etc., so that pesticide residues can be extracted as much as possible, improving the accuracy of subsequent detection.

[0023] Example 3 Based on Example 2, such as Figure 1 and Figure 10As shown, agricultural products processed by the integrated crushing and grinding machine are weighed to obtain a standard weight sample. The sample is added to acetonitrile and stirred, then filtered to obtain a filtrate. The filtrate is added to a sodium chloride solution and then vigorously shaken for 1-3 minutes. After standing, the solution is observed. If no emulsification occurs, the solution will separate into an acetonitrile phase and an aqueous phase. The upper acetonitrile phase is extracted into a centrifuge tube. If emulsification occurs, the solution is filtered and centrifuged, and then the acetonitrile phase is extracted again. The acetonitrile extract is concentrated by adding nitrogen gas. Then, a purification operation is performed by adding acetone and n-hexane solution to the acetonitrile extract to obtain an eluent. The eluent is then concentrated with nitrogen gas to obtain the sample solution to be tested. During the sample solution extraction and preparation process, vigorous shaking is required after adding sodium chloride solution to ensure thorough mixing and better extraction stratification. To enhance the shaking effect, the sample extraction system also includes a shaking device, which comprises a shaking base 61, a main shaking shaft 62, a secondary shaking shaft 63, a first C-shaped clamp 64, a second C-shaped clamp 65, and a test tube mounting column 66. Both the main shaking shaft 62 and the secondary shaking shaft 63 are rotatably mounted on the shaking base 61, and are arranged parallel to each other in the horizontal direction. One end of the main shaking shaft 62 has a main shaft mounting port, within which a first hinge shaft 67 is fixed. A first mounting plate 68 is fixed to the outer wall of the middle portion of the first C-shaped clamp 64, and the first mounting plate 68 is rotatably sleeved on the first hinge shaft 67. One end of the secondary shaking shaft 63 has a secondary shaft mounting port, within which a second hinge shaft 69 is fixed. A second mounting plate 60 is fixed to the outer wall of the middle portion of the second C-shaped clamp 65, and the second mounting plate 66 is rotatably sleeved on the second C-shaped clamp 67. On the two hinged shafts 69, the two ends of the test tube mounting column 66 are respectively located inside the C-shaped openings of the first C-shaped clamp 64 and the second C-shaped clamp 65. Both ends of the opening of the first C-shaped clamp 64 are rotatably connected to the test tube mounting column 66 via the first rotating shaft, and both ends of the opening of the second C-shaped clamp 65 are rotatably connected to the test tube mounting column 66 via the second rotating shaft. Test tube clamps are provided on the test tube mounting column 66. Test tubes containing a mixture of filtrate and sodium chloride are fixed to the test tube mounting column 66 by the test tube clamps. The mouth of the test tube is... The bottle is sealed with a stopper, and then the oscillating main shaft 62 is rotated manually or by a motor. Under the action of the first C-shaped clamp 64, the oscillating main shaft 62 drives the test tube mounting column 66 to rotate. The test tube mounting column 66 drives the oscillating secondary shaft 63 to rotate through the second C-shaped clamp 65. The first C-shaped clamp 64, the test tube mounting column 66 and the second C-shaped clamp 65 form a universal joint structure, which enables the test tube mounting column 66 to reciprocate and rotate with a large amplitude, and can be tilted up and down, so as to make the oscillation intensity greater and the mixing effect better.

[0024] Example 4 Based on Example 3, such as Figures 1 to 7As shown, the injection mechanism also includes an injector mounting bracket 45. An injection spindle is horizontally fixed to the side wall of the injection column 4. The injection spindle is rotatably mounted on the injector mounting bracket 45. An injection motor 47 is mounted on the injector mounting bracket 45. The output shaft of the injection motor 47 is connected to the injection spindle. The tube body of the micro-injector 8 is fixed to the injection column 4. An electric injection push rod 48 is installed inside the injection column 4. The electric injection push rod 48 is parallel to the micro-injector 8. The telescopic shaft of rod 48 is connected to the piston injection rod of micro-syringe 8. The head of micro-syringe 8 protrudes from one end of injection column 4. The bottom of injection mounting bracket 45 slides through the detection column box 1. A lifting electric push rod 49 is vertically installed inside the detection column box 1. The telescopic shaft of lifting electric push rod 49 moves out of the detection column box 1 and connects to injection mounting bracket 45. The injection column 4 can carry micro-syringe 8 to switch positions between sample tube 3 and injection tube 10, for use in... The sample solution in sample tube 3 is injected into injection tube 10. The specific process is as follows: the injection motor 47 drives the injection spindle to rotate, and the injection spindle drives the injection column 4 to rotate 180°, so that the puncture needle of the micro-injector 8 corresponds to the sample tube 3. Then, the lifting electric push rod 49 drives the injection device mounting bracket 45 to move upward, thereby driving the micro-injector 8 to move upward, so that the puncture needle of the micro-injector 8 pierces into the sample tube 3. Then, the injection electric push rod 48 drives the piston injection rod to move, which is used to draw the sample solution in sample tube 3 into micro-injector 8. Then, the injection motor 47 reverses, so that the injection column 4 reverses and resets. Then, the lifting electric push rod 49 drives the micro-injector 8 to move downward, so that the puncture needle of the micro-injector 8 pierces into injection tube 10. Finally, the injection electric push rod 48 drives the piston injection rod to move, injecting the sample solution in micro-injector 8 into injection tube 10, thus completing the injection operation. By using an inverted sampling method, the sample solution in the sample tube can be completely discharged, which solves the defect of incomplete sampling by traditional inclined section needles, greatly reduces the injection error, and ensures the accuracy of quantitative analysis of pesticide residues.

[0025] Example 5 Based on Example 4, such as Figures 1 to 7 As shown, one end of the test tube cap 5 has an internal threaded hole, and the test tube cap 5 has a flow guide cone hole 43. The large diameter end of the flow guide cone hole 43 is connected to the internal threaded hole, and the small diameter end of the flow guide cone hole 43 is connected to the sample inlet hole 6. The puncture needle of the micro-syringe 8 pierces the plug 7 and enters the sample inlet hole 6. The needle tip of the puncture needle does not need to be completely inserted into the sample inlet hole 6, but only partially inserted. Thus, under the guidance of the flow guide cone hole 43, the sample solution flows completely into the sample inlet hole 6, and the sample solution is sampled by the micro-syringe 8.

[0026] Furthermore, a microfiltration membrane 44 is installed inside the flow guide cone 43, which can accurately filter the fine fibers remaining in the sample extract before injection. This prevents fibers from entering the vaporization chamber and interfering with the detection signal, causing data distortion, and also avoids unvaporized fibers from entering the gas chromatography column and causing blockage. This significantly extends the service life of the chromatography column and detection equipment and improves the long-term stability of the detection process.

[0027] Example 6 Based on Example 5, such as Figures 1 to 7 As shown, a micro-pressure injection tube 14 is fixedly inserted through the side wall of the vaporization chamber 9. A piston 15 is slidably fitted inside the micro-pressure injection tube 14. The end of the piston 15 away from the vaporization chamber 9 is connected to a piston rod 16. The piston rod 16 is connected to the telescopic shaft of an electric push rod 17. The cylinder of the electric push rod 17 is installed inside the detection column box 1. The injection tube 10 is connected to the side wall of the micro-pressure injection tube 14. A vaporization tube 13 is horizontally installed inside the vaporization chamber 9. An electric heating tube 18 is threaded around the vaporization tube 13. The middle part of the vaporization tube 13 is connected to a gas chromatography column 19. The pressurized injection tube 14 and the gas delivery tube 12 are respectively connected to the two ends of the vaporization tube 13. A vaporization chamber 20 is formed inside the vaporization tube 13. Multiple pressurized holes 21 communicating with the vaporization chamber 20 are opened at both ends of the vaporization tube 13. The multiple pressurized holes 21 at both ends of the vaporization tube 13 are arranged opposite each other. When the micro-syringe 8 injects part of the sample solution into the injection tube 10, the electric push rod 17 simultaneously drives the piston rod 16 to perform a liquid-drawing action, drawing the sample solution from the injection tube 10 into the micro-pressurized injection tube 14. Then, the piston rod 16 drives the piston rod 16... The sample solution is rapidly ejected under pressure, dispersed through multiple pressure orifices 21 at one end of the vaporization tube 13, while carrier gas is continuously supplied through the gas delivery tube 12. The carrier gas enters the vaporization tube 13 through the same orifices 21 at the other end, causing collisions between the carrier gas and the sample solution within the tube. This further disperses the sample solution, enabling it to be vaporized instantly. The vaporized sample is then transported by the carrier gas to the gas chromatography column 19, where the components of the sample are separated. The compound is then delivered to the detector for pesticide residue detection. The gas chromatograph and detector are the existing structures of the gas chromatograph, which will not be described in detail. Then, the micro-syringe 8 and the micro-pressurized injection tube 14 repeat the above actions, injecting the sample solution into the vaporization tube 13 in multiple times. This abandons the traditional one-time centralized injection method and realizes small-dose, pressurized injection of the sample into the vaporization tube 13, so that the sample can be fully vaporized instantly. This fundamentally solves the problems of chromatographic peak expansion and peak tailing caused by traditional injection methods, and greatly improves the detection accuracy and reliability of the results.

[0028] Example 7 Based on Example 6, such as Figures 1 to 7As shown, the test tube rack 2 includes a base 22, a base plate 23, a central limiting plate 24, and a top plate 25. The base plate 23 is rotatably mounted on the top of the base 22. A mounting shaft 26 is coaxially fixed to the top of the base plate 23. The central limiting plate 24 is coaxially sleeved on the mounting shaft 26. The top plate 25 is detachably connected to the mounting shaft 26. Multiple first through holes 27 are formed along the circumference of the base plate 23. The central limiting plate 24 has second through holes 28 at the corresponding positions of the first through holes 27. The bottom of the top plate 25 has a groove 29 at the corresponding position of the second through hole 28. The test tube cap 5 is threaded onto the sample test tube 3. The diameter of the second through hole 28 is larger than the diameter of the test tube cap 5, and the diameter of the test tube cap 5 is larger than the diameter of the first through hole 27. The bottom of the sample test tube 3 fits into the groove 29. A positioning post 30 is fixed to the top of the mounting shaft 26, and a threaded shaft 31 is fixed to the top of the positioning post 30. The bottom of the top plate 25... The top plate 25 has a positioning groove 32, the cross-section of which is rectangular, as is the cross-section of the positioning groove 32 and the positioning post 30. The top of the top plate 25 has a third through hole 33 that connects to the positioning groove 32. The positioning post 30 is fitted into the positioning groove 32. The threaded shaft 31 passes through the third through hole 33 and is threaded to connect to the mounting cap 34. The sample tube 3 containing the sample solution is placed upside down on the test tube rack 2. Specifically, the test tube cap 5 is unscrewed, the top plate 25 is removed, and the sample tube 3 is inverted and passed through the second through hole 28 so that the bottom plate 23 contacts the test tube cap 5 to support the sample tube 3. Then, the top plate 25 is installed. The top plate 25 is positioned by the cooperation of the positioning groove 32 and the rectangular surface of the positioning post 30, so that the groove 29 is coaxial with the second through hole 28 and the bottom of the sample tube 3 is located in the groove 29. Finally, the test tube cap 5 is screwed on, thus mounting the sample tube 3 on the test tube rack 2, ensuring that the micro-syringe 8 can smoothly extract the sample solution from the sample tube 3.

[0029] Example 8 Based on Example 7, such as Figures 1 to 7As shown, a drive spindle is rotatably mounted on the top of the base 22. A motor is installed inside the base 22, and the output shaft of the motor is connected to the drive spindle via a coupling. The motor drives the test tube rack 2 to rotate through the drive spindle, enabling multiple sample test tubes 3 to be sequentially transported to the sampling position of the micro-injector 8 during multiple tests. A micro-vibration base 35 is fixed on the top of the drive spindle, and a rectangular insertion port 36 is opened on the top of the micro-vibration base 35. A rectangular insertion block 37 is fixed on the bottom of the chassis 23, and the rectangular insertion block 37 is fitted into the rectangular insertion port 36 with clearance. A spring hole 38 is provided on the inner side wall, and a spring 39 is installed in the spring hole 38. The spring 39 contacts a rectangular insert 37. The rectangular insert 37 has a fourth through hole extending through the spring hole 38 along its axial direction. The outer side wall of the micro-vibration base 35 has a small-diameter through hole 40 connecting the spring hole 38 and a threaded hole 41 coaxial with the spring hole 38. The tail of the screw 42 passes through the small-diameter through hole 40 and the fourth through hole, and its thread fits into the threaded hole 41. The gap between the micro-vibration base 35 and the rectangular insert 36 is controlled between 0.5-1.5mm, so that the test tube rack 2 produces The micro-vibration generated by the test tube rack 2 is kept within the deformation range of the orifice plug 7, ensuring that the orifice plug 7 does not interfere with the puncture needle of the micro-injector 8 and that the micro-vibration of the test tube rack 2 does not damage the puncture needle of the micro-injector 8. Specifically, a vibrator is flexibly mounted on the base 22, with the vibration axis of the vibrator corresponding to the chassis 23. The vibrator drives the chassis 23 to vibrate, and the rectangular insert 37 is connected to the micro-vibration base 35 by the screw 42, which guides the rectangular insert 37 to slide on the screw 42, in conjunction with the action of the spring 39. Force is applied to cause the rectangular insert 37 to reciprocate and vibrate, which in turn causes the entire test tube rack 2 to vibrate. The vibration amplitude of the test tube rack 2 is controlled by the gap between the micro-vibration base 35 and the rectangular insert 37, making the vibration amplitude of the test tube rack 2 very small. This vibration allows the sample test tube 3 to allow the solution remaining on the inner wall due to fibers to fall off under the action of vibration, further improving the sampling accuracy of the micro-syringe 8 and greatly reducing the loss of sample solution. By eliminating injection residues in a dual manner, the injection error is greatly reduced, ensuring the accuracy of pesticide residue quantitative analysis. In specific implementation, the flexible installation of the vibrator uses a buffer spring. The vibrator housing is mounted on the vibrator mounting frame through the buffer spring. When the vibrator is working, the rectangular insert 37 first reciprocates within the micro-vibration base 35 to generate vibration. The excess extension and contraction of the vibrator is compensated by the deformation of the buffer spring, so that the vibration amplitude of the vibrator can match the vibration amplitude of the test tube rack 2, and there will be no interference problem.

Claims

1. A pesticide residue extraction and detection device, characterized in that, The system includes a detection column box, a sample injection mechanism, and a gas path mechanism. The sample injection mechanism includes a test tube rack, a sample test tube, and an injection column. The sample test tube is inverted on the test tube rack, and the opening of the sample test tube is provided with a test tube cap. The test tube cap has a small injection hole, and a plug is inserted into the injection hole. The injection column is rotatably mounted on the top of the detection column box, and a micro-syringe is installed inside the injection column. A vaporization chamber is provided inside the detection column box, and an injection tube communicating with the vaporization chamber is provided on the detection column box. The micro-syringe extracts the liquid sample from the sample test tube by rotation and then injects it into the injection tube. The gas path mechanism includes a carrier gas cylinder and a gas delivery tube connected to the carrier gas cylinder. The gas delivery tube communicates with the vaporization chamber.

2. The pesticide residue extraction and detection device according to claim 1, characterized in that, A micro-pressure injection tube is fixedly inserted through the side wall of the vaporization chamber. A piston is slidably fitted inside the micro-pressure injection tube. The end of the piston away from the vaporization chamber is connected to a piston rod. The piston rod is connected to the telescopic shaft of an electric push rod. The cylinder of the electric push rod is installed inside the detection column box. The injection tube is connected to the side wall of the micro-pressure injection tube. A vaporization tube is horizontally installed inside the vaporization chamber. An electric heating tube is threaded around the vaporization tube. The middle part of the vaporization tube is connected to a gas chromatography column. The micro-pressure injection tube and the gas delivery tube are respectively connected to the two ends of the vaporization tube.

3. The pesticide residue extraction and detection device according to claim 2, characterized in that, The vaporization tube has a vaporization chamber inside, and multiple pressurization holes that communicate with the vaporization chamber are opened at both ends of the vaporization tube. The multiple pressurization holes at both ends of the vaporization tube are arranged opposite to each other.

4. The pesticide residue extraction and detection device according to claim 1, characterized in that, The test tube rack includes a base, a chassis, a central limiting plate, and a top plate. The chassis is rotatably mounted on the top of the base. A mounting shaft is coaxially fixed to the top of the chassis. The central limiting plate is coaxially sleeved on the mounting shaft. The top plate is detachably connected to the mounting shaft. The chassis has multiple first through holes along its circumference. The central limiting plate has second through holes at positions corresponding to the first through holes. The bottom of the top plate has a groove at positions corresponding to the second through holes. The test tube cap is threaded onto the sample test tube. The diameter of the second through hole is larger than the diameter of the test tube cap, and the diameter of the test tube cap is larger than the diameter of the first through hole. The bottom of the sample test tube fits into the groove.

5. The pesticide residue extraction and detection device according to claim 4, characterized in that, A positioning post is fixed to the top of the mounting shaft, and a threaded shaft is fixed to the top of the positioning post. A positioning groove is provided at the bottom of the top plate. The cross-section of the positioning groove and the cross-section of the positioning post are both rectangular. A third through hole is provided at the top of the top plate, which connects to the positioning groove. The positioning post is fitted into the positioning groove, and the threaded shaft passes through the third through hole and is threaded to connect to the mounting cap.

6. The pesticide residue extraction and detection device according to claim 4, characterized in that, A drive spindle is rotatably mounted on the top of the base, and a motor is installed inside the base. The output shaft of the motor is connected to the drive spindle via a coupling. A micro-vibration base is fixed on the top of the drive spindle. A rectangular insertion port is opened on the top of the micro-vibration base. A rectangular insertion block is fixed on the bottom of the chassis. The rectangular insertion block is fitted into the rectangular insertion port with clearance. A spring hole is opened on the inner side wall of the rectangular insertion port. A spring is installed in the spring hole and contacts the rectangular insertion block. A fourth through hole is opened through the rectangular insertion block along the axial direction of the spring hole. A small-diameter through hole communicating with the spring hole and a threaded hole coaxial with the spring hole are opened on the outer side wall of the micro-vibration base. The tail of the screw passes through the small-diameter through hole and the fourth through hole and is threaded into the threaded hole.

7. The pesticide residue extraction and detection device according to claim 1, characterized in that, One end of the test tube cap has an internal threaded hole, and the inside of the test tube cap has a flow guide cone hole. The large-diameter end of the flow guide cone hole is connected to the internal threaded hole, and the small-diameter end of the flow guide cone hole is connected to the sample inlet hole.

8. The pesticide residue extraction and detection device according to claim 7, characterized in that, A microfiltration membrane is installed inside the flow guide cone orifice.

9. The pesticide residue extraction and detection device according to claim 1, characterized in that, The injection mechanism also includes an injector mounting bracket. An injection spindle is horizontally fixed to the side wall of the injection column. The injection spindle is rotatably mounted on the injector mounting bracket. An injection motor is mounted on the injector mounting bracket. The output shaft of the injection motor is connected to the injection spindle. The tube of the micro-injector is fixed on the injection column. An electric injection push rod is installed inside the injection column. The electric injection push rod is parallel to the micro-injector. The telescopic shaft of the electric injection push rod is connected to the piston injection rod of the micro-injector. The head of the micro-injector protrudes from one end of the injection column.

10. The pesticide residue extraction and detection device according to claim 9, characterized in that, The bottom of the injector mounting bracket is slidably inserted into the detection column box. A lifting electric push rod is vertically installed inside the detection column box. The telescopic shaft of the lifting electric push rod extends out of the detection column box and is connected to the injector mounting bracket.

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