A fully automatic total phosphorus and total nitrogen analyzer

Abstract

This utility model provides a fully automatic total phosphorus and total nitrogen analyzer, relating to the technical field of water sample testing devices. It includes: a frame; a heating tank; a material rack; and a testing device comprising a housing and a sample chamber within the housing. The sample chamber has a sliding base with multiple cuvettes arranged along the sliding direction. Light sources and detectors are located on both sides of the sample chamber. An operation window is opened on the top surface of the housing, and a cover plate is slidably mounted on the operation window. A lever is located on the top of the cover plate. A robotic arm is provided, equipped with a gripper, a sampling needle, and a lever. The lever is fixed to the lower end of the robotic arm and can contact the lever. The horizontal line connecting the sampling needle and the lever is parallel to the sliding direction of the cover plate. When the lever opens the cover plate, the sampling needle is positioned directly above the cuvettes and can add samples to the cuvettes. This fully automatic total phosphorus and total nitrogen analyzer features a compact structure, high integration, and fully automatic operation and testing, offering high automation, testing efficiency, and accuracy.

Description

Technical Field

[0001] This utility model relates to the technical field of water sample testing devices, and in particular to a fully automatic total phosphorus and total nitrogen analyzer. Background Technology

[0002] Total phosphorus and total nitrogen are key indicators for assessing eutrophication of water bodies and are widely found in domestic sewage, industrial wastewater, and surface water. Accurate and rapid determination of total phosphorus and total nitrogen content in water is of great significance for water quality monitoring, environmental protection, and wastewater treatment process control.

[0003] In existing technologies, the measurement process typically relies on separate, functionally independent equipment. That is, the user needs to pre-treat the sample in one or more digestion devices, and then transfer the digested and cooled sample to a separate spectrophotometer for colorimetric determination. In this conventional configuration, the spectrophotometer, as a completely independent detection unit, is not integrated into the main body of the total phosphorus and total nitrogen determination device. This results in bulky equipment, cumbersome operation steps, and the potential for errors during sample transfer, making it difficult to achieve full automation and real-time data linkage. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a fully automatic total phosphorus and total nitrogen analyzer with a compact structure, high integration, fully automatic detection capability, high detection efficiency and high accuracy.

[0005] This utility model provides a fully automatic total phosphorus and total nitrogen analyzer, which includes: Heating vessel 9 is used for high-temperature and high-pressure heating of test tubes; Material rack 11 is used to hold test tubes; The detection device 5 includes a housing and a sample chamber disposed within the housing and open at the top. A mounting base is provided within the sample chamber, and a slide block is horizontally mounted on the mounting base. A placement seat is provided on the slide block, and at least two cuvettes of different widths are arranged on the placement seat along the sliding direction of the slide block. Light sources and detectors facing the cuvettes are provided on both sides of the sample chamber, and the line connecting the light source and the detector is perpendicular to the sliding direction of the slide block. An operation window 520 is provided on the top surface of the housing, located directly above the cuvette 8. A cover plate 56 is slidably mounted on the operation window 520, and the sliding direction of the cover plate is perpendicular to the sliding direction of the slide block. A lever 561 is provided on the top of the cover plate 56, and an elastic component is provided on the housing to cause the cover plate 56 to have a closing tendency. The robotic arm 2 is capable of horizontal movement. The robotic arm 2 is equipped with a gripper 71, a sampling needle 6, and a lever 231. The lever 231 is fixed to the lower end of the robotic arm 2 and can contact the lever 561. As the robotic arm 2 moves horizontally, it pushes open the cover plate 56. When the lever 231 opens the cover plate 56, the sampling needle 6 is located directly above the operation window and can add samples to the cuvette located between the light source and the detector.

[0006] It also includes a frame 1, on which a first working area, a second working area and a third working area are arranged sequentially along the length direction. A heating tank 9 is arranged in the first working area, a material rack 11 is arranged in the second working area, and a detection device 5 is arranged in the third working area. The sliding direction of the cover plate 56 is parallel to the length direction of the frame 1, and the lever 231 is arranged on the side close to the third working area.

[0007] Furthermore, the lower end of the lever 231 protrudes downward from the lower end of the robotic arm 2, and a pushing surface that can contact the lever 561 is provided on the side wall of the lever 231. The plane on which the pushing surface is located is perpendicular to the sliding direction of the cover plate 56, and an elastic layer is provided on the pushing surface.

[0008] Furthermore, the robotic arm 2 includes a vertically arranged support plate 23, on which a first slide block 233 and a second slide block 235 are vertically slidably mounted. The sampling needle 6 is disposed on the first slide block 233, and the gripper 71 is disposed on the second slide block 235. The support plate 23 is provided with a detection unit for detecting the upper limit position of the first slide block 233 and the second slide block 235. When the first slide block 233 or the second slide block 235 is at the upper limit position, the lower end of the sampling needle 6 or the gripper 71 does not protrude from the lower end of the lever 231.

[0009] Furthermore, the housing includes a base 51 and a cover 52 detachably mounted on the base 51, and the sample chamber is disposed on the base; a rectangular hole is formed on the cover 52 to form the operation window 520.

[0010] Furthermore, the mounting base 54 is provided with an adjusting screw 542 for driving the slide 55 to move.

[0011] Furthermore, the base 51 has a plurality of U-shaped positioning grooves 510 with open upper ends along its edge, and the lower inner wall of the cover 52 has horizontal positioning pins 521 corresponding to the U-shaped positioning grooves 510.

[0012] Furthermore, a frame-shaped bracket 58 is mounted on the bottom surface of the top plate of the housing via a pressure plate 57. The frame-shaped bracket 58 has symmetrically arranged strip grooves 581 on both sides. A sliding groove is formed between the strip grooves 581 and the bottom surface of the top plate. The cover plate 56 is slidably fitted in the sliding groove. The end of the cover plate 56 is bent downward to form a first connecting part 562. A second connecting part 59 is provided on the bottom surface of the top plate. The elastic component is a tension spring and is disposed between the first connecting part 562 and the second connecting part 59.

[0013] Furthermore, a connecting plate is provided at the lower end of the pressure plate 57. The length direction of the connecting plate is perpendicular to the sliding direction of the cover plate. The connecting plate is located on the edge of the operation window and on the side close to the first connecting part. One side of the connecting plate is bent downward to form the second connecting part 59. The two ends of the second connecting part 59 are provided with second mounting holes 590. The two sides of the first connecting part are provided with first mounting holes 5620. The tension spring is provided between the first mounting hole and the second mounting hole 590.

[0014] Furthermore, the frame-shaped support 58 is made of self-lubricating plastic material.

[0015] This utility model relates to a fully automatic total phosphorus and total nitrogen analyzer, equipped with a detection device featuring a sliding cover. A corresponding lever is mounted on the robotic arm. As the robotic arm moves, the lever contacts and pushes a lever, opening the cover and revealing the operating window. The horizontal line connecting the sampling needle and the lever is parallel to the sliding direction of the cover, ensuring that the sampling needle is precisely positioned above the cuvette during the robotic arm's opening process. This avoids the need for an additional independent opening drive mechanism, simplifying the control logic. When the robotic arm reaches its position, the cover is fully open, and the sampling needle is directly above the cuvette, forming a purely mechanical timing control system with high reliability, avoiding the risk of asynchrony caused by signal delays from sensor-based control methods. It eliminates the waiting time for opening confirmation and needle repositioning, allowing the arm-moving, opening, and sampling steps to be completed simultaneously, increasing the processing speed of a single sample. This fully automatic total phosphorus and total nitrogen analyzer features a compact structure, high integration, and fully automatic operation and detection capabilities, offering high automation, detection efficiency, and accuracy. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 2 This is a schematic diagram of the installation of the robotic arm in the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 3 This is a schematic diagram of the robotic arm of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 4This is a schematic diagram of the robotic arm of the fully automatic total phosphorus and total nitrogen analyzer of this utility model from another angle. Figure 5 This is a schematic diagram of the installation of the sampling needle in the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 6 This is a schematic diagram of the detection device of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 7 This is an exploded structural diagram of the detection device of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 8 for Figure 7 Enlarged view of section A in the middle; Figure 9 This is a schematic diagram of the structure of the cover of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 10 for Figure 9 Enlarged view of section B; Figure 11 This is a schematic diagram of the installation of the slide block of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 12 This is a schematic diagram of the installation of the cover plate of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 13 This is a cross-sectional view of the installation of the cover plate of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 14 This is a schematic diagram of the cover plate of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; Figure 15 This is a schematic diagram of the frame support of the fully automatic total phosphorus and total nitrogen analyzer of this utility model; In the diagram: 1. Frame, 2. Robotic arm, 5. Detection device, 6. Sampling needle, 11. Material rack, 21. X-axis sliding assembly, 22. Y-axis sliding assembly, 23. Support plate, 231. Toggle block, 232. First slide rail, 233. First slide block, 234. Second slide rail, 235. Second slide block, 236. Detection switch, 237. Contact rod, 51. Base, 510. U-shaped positioning groove, 52. Cover, 520. Operation window, 5 21. Positioning pin; 53. Sample chamber; 54. Mounting base; 541. Horizontal slide rail; 542. Adjusting screw; 55. Slide seat; 551. Placement seat; 56. Cover plate; 561. Lever; 562. First connecting part; 5620. First mounting hole; 57. Pressure plate; 58. Frame bracket; 581. Strip groove; 59. Second connecting part; 590. Second mounting hole; 7. Drive mechanism; 71. Clamping jaw; 8. Cuvette; 9. Heating tank. Detailed Implementation

[0017] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0018] See Figures 1-15 This utility model provides a fully automatic total phosphorus and total nitrogen analyzer, which includes a frame 1, a heating tank 9, a material rack 11, a detection device 5, and a robotic arm 2.

[0019] The frame 1 serves as the main body and has an overall rectangular structure. The frame 1 has a first working area, a second working area, and a third working area.

[0020] Heating vessel 9 is located in the first working area and is used to heat the test tubes at high temperature and high pressure. Heating vessel 9 has a vessel body with an open top and a cover hinged to the top of the vessel body. After the cover is closed, the heating can generate a certain pressure inside, thereby achieving pressurization and heating to complete digestion.

[0021] The material rack 11 is located in the second working area and is used to place test tubes.

[0022] The detection device 5 is located in the third working area. It includes a housing and a spectrophotometer and cuvette 8 housed inside the housing. The housing is a rectangular parallelepiped structure. An operation window 520 is provided on the top surface of the housing. The operation window 520 is located directly above the cuvette 8. A cover plate 56 is slidably mounted on the operation window 520 to close the operation window 520 and prevent external light from affecting it. A lever 561 is provided on the top of the cover plate 56. The lever 561 is vertically arranged. At the same time, an elastic component is provided on the housing. The elastic component gives the cover plate 56 a tendency to close. That is, when the lever is not subjected to external force, the cover plate 56 can be automatically closed under the action of the elastic component, thus closing the operation window 520.

[0023] The robotic arm 2 can move horizontally between different work areas for moving and placing reagent bottles, as well as placing water samples or reagents. Specifically, the robotic arm 2 has a cross slide, including an X-axis sliding assembly 21 and a Y-axis sliding assembly 22. The X-axis sliding assembly 21 can slide parallel to the length direction of the housing, and the Y-axis sliding assembly 22 can slide parallel to the width direction of the housing. The two work together to achieve movement at any position in the horizontal direction, thus enabling the placement and removal of reagent bottles and reagents.

[0024] The robotic arm 2 is equipped with a gripper 71, a sampling needle 6, and a lever 231. The gripper 71 and the sampling needle 6 are slidably mounted on the robotic arm 2 and can be raised and lowered independently. The gripper 71 is used to grasp reagent bottles and can be raised, lowered, and rotated to move and open the reagent bottles (in conjunction with the fixed gripper on the frame). The sampling needle 6 can also be raised and lowered and is used to pick up and put down reagents or samples. The raising and lowering of the sampling needle and the gripper do not interfere with each other, that is, they can each raise and lower independently.

[0025] The lever 231 is fixed to the lower end of the robotic arm 2. The lever 231 can contact the lever 561 and push open the cover plate 56 as the robotic arm 2 moves horizontally, thereby opening the operation window 520. The line connecting the sampling needle 6 and the lever 231 in the horizontal direction is parallel to the sliding direction of the cover plate 56. When the lever 231 opens the cover plate 56, the sampling needle 6 is located directly above the cuvette, thus enabling the cuvette to be sampled.

[0026] This application, by equipping a heating tank 9, can achieve pressurized heating in a closed environment inside the tank, rapidly reaching and precisely maintaining this optimal reaction condition, maximizing the decomposition efficiency of the digesting agent, achieving the most thorough oxidation effect, making the reaction more complete, and significantly improving the digestion efficiency.

[0027] It is also equipped with a detection device with a sliding cover. At the same time, a corresponding lever is set on the robotic arm. When the robotic arm moves, the lever will touch and push the lever, thereby opening the cover and revealing the operation window. The horizontal line connecting the sampling needle and the lever is parallel to the sliding direction of the cover, ensuring that the sampling needle can be brought exactly above the cuvette during the process of the robotic arm moving to open the door. This avoids the need to add an additional independent door opening drive mechanism and simplifies the control logic.

[0028] When the robotic arm moves into position, the cover is fully opened and the sampling needle is positioned directly above the cuvette, forming a purely mechanical timing control system with high reliability. This avoids signal delays and asynchrony risks caused by sensor-based control methods. It eliminates the waiting time for door opening confirmation and needle movement, allowing the two steps of moving the arm to open the door and positioning the sample to be completed simultaneously, thus improving the processing speed of a single sample.

[0029] The cover plate closes automatically via an elastic element and opens via a lever on a robotic arm. It has no other motors or circuit control components, resulting in a simple and compact structure, low cost, and high reliability.

[0030] In this embodiment, the lever is a rectangular plate structure with its upper end fixed to the robotic arm. It is vertically positioned and its plane is perpendicular to the sliding direction of the cover, thus occupying little space.

[0031] In this application, the first, second, and third working areas are arranged sequentially along the length of the frame 1; the sliding direction of the cover plate 56 is parallel to the length of the frame 1, and the lever 231 is located on the side near the third working area; the overall layout is reasonable, so that when the robotic arm moves towards the third working area, the lever naturally pushes open the cover plate, and at the same time the sampling needle accurately falls above the cuvette, optimizing the movement path of the robotic arm, reducing the idle stroke of the robotic arm, and improving the overall operating efficiency; the functional zoning of each working area is clear, which facilitates the streamlined collaborative operation of reagent pretreatment, sample digestion, and optical detection, shortens the entire process time from sample injection to result output, and has high detection efficiency.

[0032] In this embodiment, the lower end of the lever 231 protrudes downward from the lower end of the robotic arm 2. Simultaneously, a flat surface is provided on the side wall of the lever 231, which can contact the lever 561 to form a pushing surface. This pushing surface is perpendicular to the sliding direction of the cover plate 56. Furthermore, an elastic layer is provided on the pushing surface. By providing the pushing surface, it is ensured that the direction of force transmission when the lever contacts the lever is completely consistent with the sliding direction of the cover plate, thereby minimizing lateral friction and jamming risks, making the cover plate slide more smoothly and opening and closing more reliably. At the same time, the elastic layer, preferably a rubber layer, can generate flexible buffering when in contact with the lever, reducing mechanical impact and wear, and also reducing operating noise.

[0033] In this application, the robotic arm 2 also includes a vertically arranged support plate 23. A first vertical slide rail 232 and a second vertical slide rail 234 are provided on the support plate 23. A first slide block 233 is vertically mounted on the first slide rail 232, and a second slide block 235 is vertically mounted on the second slide rail 234. A first drive motor for driving the first slide block and a second drive motor for driving the second slide block are provided at the top of the support plate 23. The sampling needle 6 is vertically mounted on the first slide block 233 and can be raised and lowered. A gripper 71 is mounted on the second slide block 235. Specifically, a drive mechanism 7 is provided on the second slide block 235. The drive mechanism includes a rotating component and a clamping component. The gripper 71 is located at the output end of the drive mechanism and can clamp and rotate, with its rotation axis parallel to the second slide block. The sliding direction, in conjunction with the fixed gripper on the frame, enables the opening operation of the reagent bottle. Two detection units are provided on the support plate 23, used to detect the upper limit positions of the first slide 233 and the second slide 235 respectively. Specifically, a contact rod 237 is provided on the first slide and the second slide, and a detection switch 236 is provided on the support plate 23. Preferably, this detection switch is a sensor. When the first slide or the second slide moves to the upper stroke, the contact rod can trigger the detection switch and send a sensing signal. At this time, the lower end of the sampling needle 6 or the gripper 71 does not protrude beyond the lower end of the lever 231, ensuring smooth movement of the robotic arm during movement and preventing the sampling needle or gripper from protruding outwards (downwards) and causing collisions, ensuring reliable operation of movement and detection, and improving operational safety.

[0034] In this application, the housing includes a base 51 and a cover 52 detachably mounted on the base 51. A sample chamber 53 with an open top is provided on the base 51. The sample chamber 53 is a rectangular parallelepiped formed by bending a metal plate. A placement seat 551 is provided inside the sample chamber 53, and a cuvette 8 is placed on the placement seat 551. Light sources and detectors facing the cuvette 8 are provided on both sides of the sample chamber 53. The light sources and detectors form a spectrophotometer. The light source emits a light beam of a specific wavelength towards the cuvette, and the detector receives the light signal transmitted through the cuvette 8 and converts it into an electrical signal for detection. A rectangular opening is provided on the cover 52, forming an operation window 520 located directly above the cuvette, specifically above the placement seat. The detachable structure facilitates the adjustment and maintenance of the equipment, such as replacing the cuvette and adjusting the placement seat.

[0035] In this application, a mounting base 54 is provided in the sample chamber 53, and a horizontal slide rail 541 is provided on the mounting base 54. A slide block 55 is horizontally slidably mounted on the horizontal slide rail. The sliding direction of the slide block 55 is perpendicular to the line connecting the light source and the detector, and also perpendicular to the sliding direction of the cover plate 56. A placement seat 551 is fixed on the slide block 55, and a cuvette is provided on the placement seat 551. There are at least two cuvettes, which are arranged sequentially along the sliding direction of the slide block 55. The width of each cuvette is different. Preferably, there are two cuvettes, one of which is 3 cm wide and is used for the determination of total phosphorus, and the other is 1 cm wide and is used for the determination of total nitrogen. In this embodiment, the cuvette has a rectangular cross-section, with its sidewalls parallel to the incident direction of the light source. Its width is parallel to the line connecting the light source and the detector. An adjusting screw 542 is provided on the mounting base 54, threadedly connected to the slide 55. This screw drives the slide 55 to move horizontally, adjusting its position so that one of the cuvettes is in the detection state. This adjustment can be done manually or electrically. Different widths of cuvettes can be selected according to the detection requirements to determine total phosphorus or total nitrogen. When the lever 231 opens the cover 56, the sampling needle 6 is positioned directly above the operating window and can add samples to the cuvette located between the light source and the detector.

[0036] In this application, a plurality of U-shaped positioning grooves 510 with open upper ends are provided on the edge of the base 51. In this embodiment, a plurality of U-shaped positioning grooves 510 are provided on the front end and the left and right sides of the base. At the same time, a positioning pin 521 corresponding to the U-shaped positioning groove 510 is provided on the lower inner wall of the cover 52. The positioning pin 521 is horizontally set. When placed, the horizontal positioning pin is exactly located in the U-shaped positioning groove, thereby achieving quick and accurate positioning. It can realize the quick loading and unloading of the cover, which is convenient for the picking and placing of cuvettes and selection.

[0037] In this embodiment, a frame-shaped bracket 58 is installed on the bottom surface of the top plate of the housing, i.e., the bottom surface of the cover, through two parallel pressure plates 57. The pressure plates 57 are L-shaped, pressing and fixing the edge of the frame-shaped bracket to the bottom surface of the top plate to achieve the fixation of the frame-shaped bracket. The frame-shaped bracket is rectangular in shape and is frame-shaped. A strip groove 581 is symmetrically arranged on both sides of the frame-shaped bracket 58. A sliding groove is formed between the strip groove 581 and the bottom surface of the top plate. The cover plate 56 is placed in the sliding groove and can slide. Specifically, the end of the cover plate 56 away from the operating window is bent downward to form a first connecting part 562. At the same time, a second connecting part 59 is provided on the bottom surface of the top plate. The elastic component is a tension spring, which is arranged between the first connecting part 562 and the second connecting part 59, so that the cover plate has a tendency to return and close.

[0038] Specifically, a connecting plate is provided at the lower end of the pressure plate 57. The length direction of the connecting plate is perpendicular to the sliding direction of the cover plate. The connecting plate is set on the edge of the operating window and is located on the side close to the first connecting part. One side of the connecting plate is bent downward to form a second connecting part 59. Second mounting holes 590 are provided at both ends of the second connecting part 59. First mounting holes 5620 are provided on both sides of the first connecting part. There are two tension springs, which are respectively set between the first mounting holes and the second mounting holes 590. Its structure is simple and compact, easy to install, occupies little space, and has low manufacturing cost. At the same time, it can realize the smooth reset of the cover plate, avoid deflection and jamming, and has good stability in use.

[0039] To further improve the smoothness of the cover plate's sliding, in this application, the frame bracket 58 is made of self-lubricating plastic material, which has a certain self-lubricating property, reduces the friction between the cover plate and the cover plate, ensures the smooth sliding of the cover plate, avoids lateral thrust on the robotic arm due to friction, protects the robotic arm, and improves the overall operational reliability and stability.

[0040] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A fully automatic total phosphorus and total nitrogen determination instrument, characterized in that, The application relates to a high-temperature and high-pressure heating device for a test tube. The device comprises a heating tank for high-temperature and high-pressure heating of a test tube, a rack for placing the test tube, a detection device, a mechanical arm, and a rack. The detection device comprises a shell and a sample chamber arranged in the shell and having an open upper end, wherein an installation seat is arranged in the sample chamber, a sliding seat is horizontally slidably arranged on the installation seat, a placing seat is arranged on the sliding seat, at least two cuvettes with different width sizes are arranged on the placing seat along the sliding direction of the sliding seat, light sources and detectors are arranged on both sides of the sample chamber and face the cuvettes, the connection lines of the light sources and the detectors are perpendicular to the sliding direction of the sliding seat, an operation window is formed in the top surface of the shell and is located directly above the cuvettes, a cover plate is slidably arranged on the operation window and the sliding direction of the cover plate is perpendicular to the sliding direction of the sliding seat, a push rod is arranged on the top of the cover plate, and elastic components are arranged on the shell and make the cover plate have a closing trend. The mechanical arm can move horizontally, the mechanical arm is provided with a clamping jaw, a sampling needle and a push block, the push block is fixed to the lower end of the mechanical arm and can be in contact with the push rod and push the cover plate away along with the horizontal movement of the mechanical arm, and when the push block opens the cover plate, the sampling needle is located directly above the operation window and can add sample to the cuvette between the light source and the detector. The device further comprises a rack, the rack is sequentially provided with a first working area, a second working area and a third working area along the length direction, the heating tank is arranged in the first working area, the rack for placing the test tube is arranged in the second working area, and the detection device is arranged in the third working area; the sliding direction of the cover plate is parallel to the length direction of the rack, and the push block is arranged on one side close to the third working area.

2. The automatic total phosphorus and total nitrogen determination instrument according to claim 1, characterized in that: The lower end of the push block protrudes downward from the lower end of the mechanical arm, a pushing surface that can be in contact with the push rod is arranged on the side wall of the push block, the plane where the pushing surface is located is perpendicular to the sliding direction of the cover plate, and an elastic layer is arranged on the pushing surface.

3. The automatic total phosphorus and total nitrogen determination instrument according to claim 1, characterized in that: The mechanical arm comprises a vertically arranged support plate, a first sliding seat and a second sliding seat are vertically slidably arranged on the support plate, the sampling needle is arranged on the first sliding seat, the clamping jaw is arranged on the second sliding seat, and a detection unit for detecting the upper limit positions of the first sliding seat and the second sliding seat is arranged on the support plate; when the first sliding seat or the second sliding seat is located at the upper limit position, the lower end of the sampling needle or the clamping jaw does not protrude from the lower end of the push block.

4. The automatic total phosphorus and total nitrogen determination instrument according to claim 1, characterized in that: The shell comprises a base and a cover body that is detachably arranged on the base, and the sample chamber is arranged on the base; a rectangular hole body is formed in the cover body and the operation window is formed.

5. The automatic total phosphorus and total nitrogen determination instrument according to claim 1, characterized in that: An adjusting screw for driving the sliding seat to move is arranged on the installation seat.

6. The automatic total phosphorus and total nitrogen determination instrument according to claim 1, characterized in that: The edge of the base is provided with a plurality of U-shaped positioning grooves with open upper ends, and the lower end inner wall of the cover body is provided with horizontal positioning pins corresponding to the U-shaped positioning grooves.

7. The automatic total phosphorus and total nitrogen determination instrument according to claim 5, characterized in that: ​ 8. The automatic total phosphorus and total nitrogen determination instrument according to claim 1, characterized in that: The bottom surface of the top plate of the shell is provided with a frame-shaped support through a pressing plate, two sides of the frame-shaped support are symmetrically provided with strip-shaped grooves, the strip-shaped grooves and the bottom surface of the top plate form sliding grooves, the cover plate is slidably arranged in the sliding grooves, the end of the cover plate is downwardly bent and forms a first connecting part, the bottom surface of the top plate is provided with a second connecting part, and the elastic part is a tension spring and is arranged between the first connecting part and the second connecting part.

9. The automatic total phosphorus and total nitrogen determination instrument according to claim 8, characterized in that: The lower end of the pressing plate is provided with a connecting plate, the length direction of the connecting plate is perpendicular to the sliding direction of the cover plate, the connecting plate is arranged at the edge of the operation window and is located at the side close to the first connecting part, one side of the connecting plate is downwardly bent and forms the second connecting part, the two ends of the second connecting part are provided with second mounting holes, the two sides of the first connecting part are provided with first mounting holes, and the tension spring is arranged between the first mounting holes and the second mounting holes.

10. The automatic total phosphorus and total nitrogen determination instrument according to claim 8, characterized in that: The frame-shaped support is made of self-lubricating plastic material.

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