A detection method for heavy metal content in different edible parts of common vegetables and fruits

Abstract

The application discloses a detection method for heavy metal content in different edible parts of common vegetables and fruits, which comprises the following steps: (1) cleaning dirt on the surface of the vegetables and fruits by using a cleaning device; (2) selecting different edible parts of the vegetables and fruits, and respectively preparing sample solutions by using a microwave digestion method, and meanwhile, carrying out a blank test; (3) injecting the sample solutions into an inductively coupled plasma mass spectrometer, measuring signal response values of the to-be-detected elements and internal standard elements, taking the concentration of the to-be-detected elements as the abscissa, taking the ratio of the response signal values of the to-be-detected elements and the selected internal standard elements as the ordinate, and drawing a standard curve; (4) injecting the blank solution and the sample solution into the inductively coupled plasma mass spectrometer respectively, measuring signal response values of the to-be-detected elements and the internal standard elements, and obtaining the concentration of the to-be-detected elements in the digestion solution according to the standard curve; and (5) calculating the analysis result.

Description

Technical Field

[0001] This invention belongs to the field of heavy metal content detection technology, and specifically relates to a method for detecting heavy metal content in different edible parts of common fruits and vegetables. Background Technology

[0002] The main sources of heavy metals in vegetables and fruits are soil pollution, water pollution, pesticide residues, and atmospheric deposition. Soil pollution plays a significant role in the contamination of crops; therefore, the determination of heavy metal content in vegetables and fruits is often accompanied by the determination of heavy metal content in the soil.

[0003] Currently, Chinese patent publication number CN116338149, published on June 27, 2023, discloses a method for detecting heavy metals in food contact paper, specifically including the following steps: Step 1: Preparation; Step 2: Safety study of harmful substances in paper contact paper and testing of relevant indicator data; Step 3: Heavy metal detection method and plasticizer detection; Step 4: Combining experimental data and summarizing analysis; Step 5: Establishment of heavy metal and plasticizer testing methods; Step 6: Combining experimental data and summarizing analysis.

[0004] Among them, microwave digestion atomic spectroscopy was used to determine the detection of heavy metals such as lead, chromium, and cadmium in paper food contact materials. The digestion conditions were optimized to improve the degree of sample digestion and improve the detection accuracy.

[0005] When detecting heavy metals in common fruits and vegetables, microwave digestion and inductively coupled plasma mass spectrometry are also required. For fruits and vegetables with a lot of surface dirt, such as potatoes, water chestnuts, and snow lotus fruit, the dirt on the surface of the fruits and vegetables needs to be cleaned before heavy metal detection to avoid the heavy metals in the dirt affecting the subsequent heavy metal detection. However, the existing technology often fails to clean the surface thoroughly, which can easily affect the subsequent heavy metal detection. Summary of the Invention

[0006] The purpose of this invention is to provide a method for detecting the heavy metal content in different edible parts of common fruits and vegetables, which helps to avoid the influence of surface dirt on heavy metal detection.

[0007] The above-mentioned technical objective of this invention is achieved through the following technical solution: a method for detecting the heavy metal content in different edible parts of common fruits and vegetables, comprising the following steps:

[0008] (1) Use a cleaning device to clean the dirt and grime on the surface of fruits and vegetables;

[0009] (2) Select different edible parts of fruits and vegetables, prepare sample solutions using microwave digestion, and perform blank tests at the same time;

[0010] (3) Inject the sample solution into the inductively coupled plasma mass spectrometer and measure the signal response values ​​of the analyte and the internal standard. Plot a standard curve with the concentration of the analyte as the abscissa and the ratio of the response signal values ​​of the analyte to the selected internal standard as the ordinate.

[0011] (4) Inject the blank solution and the sample solution into the inductively coupled plasma mass spectrometer, respectively, and measure the signal response values ​​of the analyte and the internal standard. The concentration of the analyte in the digestion solution is obtained according to the standard curve.

[0012] (5) Calculation of analytical results: The formula for calculating heavy metal content is as follows:

[0013] X = (c1 - c0) * V / m

[0014] In the formula:

[0015] X — The content of heavy metals, mg / kg;

[0016] ci — heavy metal concentration in the sample, mg / L;

[0017] c0 — Concentration of heavy metals in blank sample, mg / L;

[0018] V—Sample volume at final volume, mL;

[0019] m—mass of the sample, in grams.

[0020] By adopting the above technical solution, before heavy metal testing of fruits and vegetables is required, the surface dirt on the fruits and vegetables is first cleaned using a cleaning device, thereby avoiding the influence of surface dirt on heavy metal testing and improving the accuracy of the test.

[0021] A further setting of the present invention is as follows: In the preparation of the sample solution by microwave digestion: weigh 0.2g-0.5g of solid sample (accurate to 0.001g; for samples with high water content, the sample amount can be appropriately increased to 1g) or accurately transfer 1.00mL-3.00mL of liquid sample into the inner microwave digestion vessel. For samples containing ethanol or carbon dioxide, first heat them at low temperature on a hot plate to remove ethanol or carbon dioxide, add 5mL-10mL of nitric acid, cover and let stand for 1 hour or overnight, tighten the lid, and digest according to the standard operating procedure of the microwave digester. After cooling, remove the vessel, slowly open the lid to release air, rinse the inner lid with a small amount of water, place the digestion vessel on a temperature-controlled hot plate or in an ultrasonic water bath, heat at 100℃ for 30min or ultrasonically degas for 2min-5min, dilute with water to 25mL or 50mL, mix well and set aside, and perform a blank test at the same time.

[0022] A further provision of the present invention is that: when the content of each element in the sample is greater than 1 mg / kg, the absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 10% of the arithmetic mean; when the content is less than or equal to 1 mg / kg and greater than 0.1 mg / kg, the absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 15% of the arithmetic mean; and when the content is less than or equal to 0.1 mg / kg, the absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 20% of the arithmetic mean.

[0023] A further configuration of the present invention is as follows: the cleaning device includes a base, a cleaning bucket disposed on the base and into which water and the fruits and vegetables to be cleaned are placed, a lifting cylinder disposed on one side of the base, a connecting arm disposed on the upper end of the lifting cylinder, and a washing component disposed at the end of the connecting arm away from the lifting cylinder and used for descending and entering the cleaning bucket for washing.

[0024] By adopting the above technical solution, after water and fruits and vegetables to be cleaned are put into the cleaning bucket, the lifting cylinder drives the washing component to move down through the connecting arm. Then, the washing component enters the cleaning bucket and can wash the surface of the fruits and vegetables, thus cleaning the dirt on the surface of the fruits and vegetables.

[0025] A further configuration of the present invention is as follows: the washing assembly includes a first circular plate disposed at the end of the connecting arm away from the lifting cylinder, a servo motor disposed at the center of the lower surface of the first circular plate, a drive gear disposed on the output shaft of the servo motor, a second circular plate disposed below the drive gear, a plurality of support arms disposed between the first circular plate and the second circular plate, a plurality of connecting shafts rotatably connected to the periphery of the second circular plate, a driven gear disposed at the upper end of the connecting shaft and meshing with the drive gear, and a first brush bristle disposed at the lower periphery of the connecting shaft for washing the surface of fruits and vegetables.

[0026] By adopting the above technical solution, the servo motor drives the drive gear to rotate. Since the driven gears at the upper end of multiple connecting shafts mesh around the drive gear, the drive gear can drive the driven gears and connecting shafts to rotate. The connecting shafts can then drive the first brush at the lower end to rotate, and the first brush can then clean the dirt off the surface of fruits and vegetables.

[0027] A further provision of the present invention is that: the second circular plate is also provided with a material-collecting component for collecting and draining the washed fruits and vegetables; the connecting shaft includes a first shaft whose upper end is fixed to the driven gear, a second shaft whose upper end is hinged to the lower end of the first shaft and whose lower end is used to connect the first bristles; the material-collecting component includes a plurality of bushings disposed on the periphery of the second circular plate and for the hinge point of the first shaft and the second shaft to move up and down, a magnet block disposed on the lower surface of the second circular plate and for attracting the second shaft, an attraction inclined surface formed on the magnet block and causing the second shaft to tilt toward the central axis of the second circular plate, and an adjustment member disposed between the second circular plate and the support arm and for driving the driven gear to move up and down.

[0028] By adopting the above technical solution, after washing, the fruits and vegetables need to be removed from the washing tub. The adjusting component drives the driven gear to move down, so that the hinge point between the first shaft and the second shaft moves down and then disengages from the bushing. Then, under the attraction of the magnet, the second shaft can swing towards the magnet and then be attracted to the attraction inclined surface. At this time, the second shaft can tilt towards the central axis of the second circular plate. When multiple second shafts tilt towards the central axis of the second circular plate at the same time, they can grab the fruits and vegetables in the center of the washing tub. Then, the lifting cylinder drives the second shaft to move up and disengage from the washing tub, thus completing the grabbing of the fruits and vegetables from the washing tub. After being grabbed by the second shaft, the fruits and vegetables stay above the washing tub for a period of time, so that the surface water of the fruits and vegetables can be drained. The experimenter can then manually break open the second shaft to take out the fruits and vegetables inside.

[0029] When it is necessary to clean the surface dirt of fruits and vegetables again, the driven gear is moved upward by the adjusting component, so that the hinge point between the first shaft and the second shaft moves upward and enters the bushing. At this time, the second shaft can be separated from the magnet. At the same time, under the limiting action of the bushing, the second shaft can return to the vertical position. Then, the first bristles at the lower end of the second shaft can easily enter the cleaning bucket to scrub the surface dirt of the fruits and vegetables.

[0030] A further configuration of the present invention includes: the adjusting component comprising a plurality of internally threaded sleeves disposed on the periphery of the second circular plate and corresponding to the positions of the bushings, a fixed arm disposed on the support arm, a through hole opened at the end of the fixed arm away from the support arm, a lifting shaft passing through the through hole, a threaded end disposed at the lower end of the lifting shaft and used for threaded connection within the internally threaded sleeve, a connecting plate disposed at the upper end of the lifting shaft, a compression spring sleeved on the lifting shaft with its upper end abutting against the connecting plate and its upper and lower ends abutting against the fixed arm, an adjusting gear disposed on the lifting shaft and meshing with the driven gear, and an adjusting plate disposed on the lifting shaft and located on the upper and lower sides of the driven gear.

[0031] By adopting the above technical solution, when the servo motor drives the active gear to rotate in the forward direction and drives the first brush to brush the surface dirt of the fruits and vegetables, the driven gear rotates and drives the adjusting gear to rotate. At this time, since the threaded end of the lifting shaft cannot be threaded into the inner thread sleeve, the lifting shaft and the adjusting gear are at the upper limit position, thereby keeping the hinge point between the first shaft and the second shaft in the bushing, ensuring that the first brush stably brushes the surface dirt of the fruits and vegetables.

[0032] When fruits and vegetables need to be picked up, the servo motor drives the drive gear to rotate in the opposite direction. After the driven gear rotates in the opposite direction, it drives the adjusting gear to rotate in the opposite direction. At this time, under the downward pressure of the compression spring, the threaded end of the lifting shaft can be threaded into the inner threaded sleeve, thereby causing the lifting shaft and the adjusting gear to move down. The adjusting plate on the lifting shaft can then drive the driven gear to move down. At the same time, when the hinge point between the first shaft and the second shaft moves to below the bushing, the servo motor can stop rotating in the opposite direction. At this time, the lifting shaft and the adjusting gear are at the lower limit position. Then, under the attraction of the magnet, multiple second shafts can be driven to tilt towards the central axis of the second circular plate at the same time, and finally the fruits and vegetables in the center of the washing tank can be picked up.

[0033] A further feature of the present invention is that a guide ring surface is provided on the inner circumferential wall of the lower end of the bushing.

[0034] By adopting the above technical solution, when the hinge point of the first shaft and the second shaft needs to be moved upward and enter the bushing, the guide ring surface opened on the inner wall of the lower end of the bushing can conveniently guide the second shaft, which is conducive to the second shaft smoothly entering the bushing and returning to the vertical state.

[0035] A further configuration of the present invention is as follows: a stepper motor is provided on the lower side of the second circular plate, a fixed disk is connected to the output shaft of the stepper motor, a second brush bristle for washing the surface of fruits and vegetables is provided on the periphery of the lower surface of the fixed disk, and a vibrating arm for impacting the second shaft in an inclined state is provided on the side wall of the fixed disk.

[0036] By adopting the above technical solution, a stepper motor is first used to drive the fixed plate and the second brush to rotate, thereby brushing the dirt on the surface of fruits and vegetables through the second brush. At the same time, when the fruits and vegetables are picked up by the tilted second shaft, the stepper motor continues to rotate. Since the second shaft is tilted and close to the fixed plate, the vibrating arm on the side wall of the fixed plate can hit multiple second shafts in sequence as the fixed plate rotates, thereby causing the second shafts to vibrate and swing on the magnet block, which ultimately helps the water on the surface of the fruits and vegetables to drain quickly.

[0037] A further feature of the present invention is that the bottom of the washing tub is provided with a placement platform with a downwardly recessed upper surface for placing fruits and vegetables, and a third bristle is provided on the periphery of the upper surface of the placement platform.

[0038] By adopting the above technical solution, when fruits and vegetables enter the washing tub, they can come into contact with the third bristles of the placement platform. At the same time, the downward-concave placement platform can ensure that the fruits and vegetables are located in the center of the washing tub. Then, the fruits and vegetables rotate under the action of the first and second bristles, and the third bristles can clean the dirt and grime from the surface of the fruits and vegetables.

[0039] In summary, the present invention has the following beneficial effects: Before heavy metal testing of fruits and vegetables, the surface dirt is first cleaned using a cleaning device to avoid the impact of surface dirt on heavy metal testing; after water and fruits and vegetables to be cleaned are placed in the cleaning tub, the washing assembly is moved down by a lifting cylinder through a connecting arm, and then the washing assembly enters the cleaning tub. A servo motor drives the drive gear to rotate forward. Since the driven gears at the upper ends of multiple connecting shafts mesh around the drive gear, the drive gear can drive the driven gears and connecting shafts to rotate, and the connecting shafts can drive the first brush at the lower end to rotate, and then the first brush can wash the dirt off the surface of the fruits and vegetables; at the same time, a stepper motor drives the fixed plate and the second brush to rotate, thereby brushing the dirt off the upper surface of the fruits and vegetables; after the fruits and vegetables rotate under the drive of the first and second brushes, the third brush on the platform can clean the dirt off the lower surface of the fruits and vegetables.

[0040] When the servo motor drives the active gear to rotate in the forward direction and drives the first brush to brush the dirt off the surface of the fruits and vegetables, the driven gear rotates and drives the adjusting gear to rotate. At this time, since the threaded end of the lifting shaft cannot be threaded into the inner threaded sleeve, the lifting shaft and the adjusting gear are at the upper limit position, thereby keeping the hinge point between the first shaft and the second shaft in the bushing, ensuring that the first brush stably brushes the dirt off the surface of the fruits and vegetables.

[0041] When the fruits and vegetables are removed from the washing tub after washing, the servo motor drives the drive gear to rotate in the opposite direction. This reverse rotation of the driven gear then drives the adjusting gear to rotate in the opposite direction. At this point, under the downward pressure of the compression spring, the threaded end of the lifting shaft is threaded into the internal threaded sleeve, causing the lifting shaft and adjusting gear to move downwards. The adjusting plate on the lifting shaft then drives the driven gear downwards. Simultaneously, when the hinge point between the first and second shafts moves below the bushing, the servo motor stops rotating in the opposite direction. At this point, the lifting shaft and adjusting gear are at their lower limit position. Then, under the attraction of the magnet, multiple second shafts simultaneously tilt towards the central axis of the second circular plate. The device is tilted so that the fruits and vegetables in the center of the washing tub can be grabbed. Then, the lifting cylinder drives the second shaft to move upward and detach from the washing tub, thus removing the fruits and vegetables from the tub. After being grabbed by the second shaft, the fruits and vegetables remain above the washing tub for a period of time, while the stepper motor continues to rotate. At this time, because the second shaft is tilted and close to the fixed plate, the vibrating arms on the side wall of the fixed plate will hit multiple second shafts in sequence as the fixed plate rotates. This causes the second shafts to vibrate and swing on the magnet block, which helps to quickly drain the water from the surface of the fruits and vegetables. After the water has drained, the experimenter can manually break open the second shaft to remove the fruits and vegetables inside.

[0042] When it is necessary to clean the surface dirt of fruits and vegetables again, the servo motor drives the drive gear to rotate in the forward direction. After the driven gear rotates, it drives the adjusting gear to rotate. Then the threaded end of the lifting shaft can rotate out of the inner threaded sleeve. After the lifting shaft and the adjusting gear move up, they can drive the driven gear to move up through the adjusting plate. Then the hinge point between the first shaft and the second shaft moves up and can enter the bushing. The second shaft disengages from the magnet. At the same time, under the limiting action of the bushing, the second shaft can return to the vertical position. Then the first bristles at the lower end of the second shaft can easily enter the cleaning bucket to scrub the surface dirt of the fruits and vegetables. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the cleaning device in this invention;

[0045] Figure 2 This is an enlarged view of the structure of the washing component in the cleaning device of the present invention;

[0046] Figure 3This is a partial structural cross-sectional view of the cleaning device in this invention, in which the servo motor is rotating in the forward direction and the second shaft is in a vertical position;

[0047] Figure 4 This is a magnified view of a partial structure of the washing component in this invention, showing only a single driven gear.

[0048] Figure 5 This is a partially enlarged view of the connection relationship between the driving gear, the second circular plate, and multiple driven gears in this invention;

[0049] Figure 6 This is a partial structural cross-sectional view of the second circular plate, the first shaft, the second shaft, and the bushing in this invention;

[0050] Figure 7 This is a partial structural cross-sectional view of the cleaning device of the present invention. At this time, the servo motor rotates in the opposite direction and the second shaft tilts and is attracted to the magnet block.

[0051] In the diagram, 1. Base; 2. Cleaning tub; 3. Lifting cylinder; 4. Connecting arm; 5. Washing assembly; 51. First circular plate; 52. Servo motor; 53. Drive gear; 54. Second circular plate; 55. Support arm; 56. Connecting shaft; 561. First shaft; 562. Second shaft; 57. Driven gear; 58. First bristle; 6. Material handling assembly; 61. Bushing; 611. Guide ring; 62. Magnet block; 63. Attraction inclined surface; 64. Adjusting component; 641. Internal threaded sleeve; 642. Fixed arm; 643. Through hole; 644. Lifting shaft; 645. Threaded end; 646. Connecting plate; 647. Compression spring; 648. Adjusting gear; 649. Adjusting plate; 7. Stepper motor; 71. Fixed plate; 711. Second bristle; 712. Vibrating arm; 8. Placement platform; 81. Third bristle. Detailed Implementation

[0052] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0053] A method for detecting heavy metal content in different edible parts of common fruits and vegetables, comprising the following steps:

[0054] (1) Use a cleaning device to clean the dirt and grime on the surface of fruits and vegetables;

[0055] (2) Select different edible parts of fruits and vegetables, prepare sample solutions using microwave digestion, and perform blank tests at the same time;

[0056] (3) Inject the sample solution into the inductively coupled plasma mass spectrometer and measure the signal response values ​​of the analyte and the internal standard. Plot a standard curve with the concentration of the analyte as the abscissa and the ratio of the response signal values ​​of the analyte to the selected internal standard as the ordinate.

[0057] (4) Inject the blank solution and the sample solution into the inductively coupled plasma mass spectrometer, respectively, and measure the signal response values ​​of the analyte and the internal standard. The concentration of the analyte in the digestion solution is obtained according to the standard curve.

[0058] (5) Calculation of analytical results: The formula for calculating heavy metal content is as follows:

[0059] X = (c1 - c0) * V / m

[0060] In the formula:

[0061] X — The content of heavy metals, mg / kg;

[0062] ci — heavy metal concentration in the sample, mg / L;

[0063] c0 — Concentration of heavy metals in blank sample, mg / L;

[0064] V—Sample volume at final volume, mL;

[0065] m — mass of the sample, in grams.

[0066] In the preparation of sample solutions using microwave digestion: Weigh 0.2g-0.5g of solid sample (accurate to 0.001g; for samples with high water content, the sample amount can be increased to 1g) or accurately transfer 1.00mL-3.00mL of liquid sample into the microwave digestion vessel. For samples containing ethanol or carbon dioxide, first heat them on a hot plate at low temperature to remove the ethanol or carbon dioxide. Add 5mL-10mL of nitric acid, cover and let stand for 1 hour or overnight. Tighten the lid and digest according to the standard operating procedure of the microwave digester. After cooling, remove the vessel, slowly open the lid to release the gas, rinse the inner lid with a small amount of water, place the digestion vessel on a temperature-controlled hot plate or in an ultrasonic water bath, heat at 100℃ for 30 minutes or degas ultrasonically for 2-5 minutes, and dilute with water to 25mL or 50mL. Mix well and set aside. At the same time, perform a blank test.

[0067] Meanwhile, when the content of each element in the sample is greater than 1 mg / kg, the absolute difference between two independent determinations obtained under repeatability conditions shall not exceed 10% of the arithmetic mean; when the content is less than or equal to 1 mg / kg and greater than 0.1 mg / kg, the absolute difference between two independent determinations obtained under repeatability conditions shall not exceed 15% of the arithmetic mean; when the content is less than or equal to 0.1 mg / kg, the absolute difference between two independent determinations obtained under repeatability conditions shall not exceed 20% of the arithmetic mean.

[0068] Reference Figure 1 , Figure 2 , Figure 3 The cleaning device in step (1) includes a base 1, a cleaning bucket 2, a lifting cylinder 3, a connecting arm 4, and a washing assembly 5. The cleaning bucket 2 is placed on the base 1 and is used to supply water and place the fruits and vegetables to be cleaned inside. A placement platform 8 is welded to the bottom of the cleaning bucket 2. The upper surface of the placement platform 8 is recessed downward for placing fruits and vegetables. A third brush bristle 81 is bonded to the periphery of the upper surface of the placement platform 8. The lifting cylinder 3 is located on one side of the base 1, and the lower end of the lifting cylinder 3 is fixed to the base 1 by bolts. The lifting cylinder 3 extends and retracts in the vertical direction. At the same time, one end of the connecting arm 4 is fixed to the upper end of the lifting cylinder 3 by bolts.

[0069] Reference Figure 1 , Figure 2 , Figure 3 The washing assembly 5 is located at the end of the connecting arm 4 away from the lifting cylinder 3. After being lowered by the lifting cylinder 3, the washing assembly 5 enters the washing tub 2 to wash away dirt and grime from the surface of fruits and vegetables. This washing assembly 5 includes a first circular plate 51, a servo motor 52, a drive gear 53, a second circular plate 54, a support arm 55, a connecting shaft 56, a driven gear 57, and first bristles 58. The first circular plate 51 is bolted to the end of the connecting arm 4 away from the lifting cylinder 3, while the servo motor 52 is bolted to the center of the lower surface of the first circular plate 51. The drive gear 53 is keyed to the output shaft at the lower end of the servo motor 52. The second circular plate 54 is located below the drive gear 53. Multiple support arms 55 are provided and evenly distributed along the periphery of the first circular plate 51. The upper end of the support arm 55 is welded to the first circular plate 51 and the lower end is welded to the second circular plate 54. The second circular plate 54 can be supported by the support arms 55. At the same time, multiple connecting shafts 56 are provided and evenly distributed along the periphery of the second circular plate 54. The connecting shafts 56 are rotatably connected to the second circular plate 54. The driven gear 57 is welded to the upper end of the connecting shaft 56 and meshes with the driving gear 53. The driving gear 53 can drive the driven gear 57 and the connecting shaft 56 to rotate. The first bristles 58 are bonded to the periphery of the lower end of the connecting shaft 56. The first bristles 58 can abut against the periphery of the fruit and vegetable.

[0070] Reference Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 The second circular plate 54 is also equipped with a material-collecting component 6, which is used to collect and drain the washed fruits and vegetables. Meanwhile, the connecting shaft 56 includes a first shaft 561 with its upper end welded to the driven gear 57, and a second shaft 562 with its upper end hinged to the lower end of the first shaft 561 and its lower end used to connect to the first brush bristles 58. The connecting shaft 56 is made of iron. The material-collecting component 6 includes a bushing 61, a magnet 62, an attractive inclined surface 63, and an adjusting component 64. Multiple bushings 61 are provided, each corresponding to a multiple connecting shaft 56. The bushings 61 are integrally mounted on the second circular plate 54 and provide... The connecting shaft 56 passes through, thus enabling the connecting shaft 56 to rotate on the second circular plate 54. A guide ring surface 611 is also provided on the inner circumferential wall of the lower end of the bushing 61. At the same time, the hinge point of the first shaft 561 and the second shaft 562 is located at the position of the bushing 61. The magnet block 62 is bonded to the lower surface of the second circular plate 54 and corresponds to the position of the bushing 61. The attraction slope 63 is provided on the magnet block 62 and allows the second shaft 562 to be attracted. After the second shaft 562 is attracted to the magnet block 62, the second shaft 562 can be tilted towards the central axis of the second circular plate 54.

[0071] Reference Figure 3 , Figure 4 , Figure 5The adjusting component 64 is disposed between the second circular plate 54 and the support arm 55 and is used to drive the driven gear 57 to move up and down. This adjusting component 64 includes an internal threaded sleeve 641, a fixed arm 642, a through hole 643, a lifting shaft 644, a threaded end 645, a connecting plate 646, a compression spring 647, an adjusting gear 648, and an adjusting plate 649. Multiple internal threaded sleeves 641 are integrally disposed on the second circular plate 54, with each internal threaded sleeve 641 corresponding to a different shaft sleeve 61. The fixed arm 642 is welded to the inner wall of the support arm 55. The through hole 643 is located at the end of the fixed arm 642 away from the support arm 55, and the lifting shaft 644 passes through the through hole 643, allowing it to move up and down within the through hole 643. The threaded end 645 is integrally disposed on the second circular plate 54. The threaded end 645 is located at the lower end of the lifting shaft 644 and is used for threaded connection within the internal threaded sleeve 641. The connecting plate 646 is welded to the upper end of the lifting shaft 644, and the compression spring 647 is sleeved on the lifting shaft 644. The upper end of the compression spring 647 abuts against the connecting plate 646, and the lower end abuts against the fixed arm 642. The downward pressure of the compression spring 647 causes the lifting shaft 644 to tend to move downward. The adjusting gear 648 is welded to the lifting shaft 644 and meshes with the driven gear 57. Two adjusting plates 649 are provided and welded to the lifting shaft 644 on the upper and lower sides of the adjusting gear 648, respectively. The two adjusting plates 649 are located on the upper and lower sides of the driven gear 57, respectively. The driven gear 57 can be moved up and down by adjusting the plates 649.

[0072] Reference Figure 2 , Figure 3 , Figure 7 A stepper motor 7 is bolted to the lower side of the second circular plate 54, and a fixed plate 71 is welded to the output shaft of the stepper motor 7. A second brush bristle 711 is bonded to the periphery of the lower surface of the fixed plate 71, which can be used to wash the surface of fruits and vegetables. At the same time, a vibrating arm 712 is integrally provided on the side wall of the fixed plate 71. When the second shaft 562 is in a vertical state, the vibrating arm 712 does not interfere with the second shaft 562. However, when the second shaft 562 is attracted by the magnet block 62 and is in an inclined state, the vibrating arm 712 interferes with the second shaft 562. At this time, the vibrating arm 712 can be used to strike the inclined second shaft 562.

[0073] Principle: Before heavy metal testing of fruits and vegetables, a cleaning device is first used to remove dirt and grime from their surfaces, thus preventing the dirt and grime from affecting the heavy metal detection. Water and the fruits and vegetables to be cleaned are placed in the cleaning tank 2. A lifting cylinder 3, via a connecting arm 4, moves the washing assembly 5 downwards. The washing assembly 5 then enters the cleaning tank 2, and a servo motor 52 drives the drive gear 53 to rotate forward. Since the driven gears 57 on the upper ends of multiple connecting shafts 56 mesh around the drive gear 53, the drive gear... Wheel 53 can drive driven gear 57 and connecting shaft 56 to rotate, and connecting shaft 56 can drive the first brush 58 at the lower end to rotate. Then the first brush 58 can wash the dirt on the surface of fruits and vegetables. At the same time, stepper motor 7 drives fixed plate 71 and second brush 711 to rotate, so that the second brush 711 can wash the dirt on the upper surface of fruits and vegetables. After the fruits and vegetables are rotated by the first brush 58 and the second brush 711, the third brush 81 on the platform 8 can clean the dirt on the lower surface of fruits and vegetables.

[0074] When the servo motor 52 drives the drive gear 53 to rotate in the forward direction and drives the first brush bristles 58 to brush the dirt off the surface of the fruits and vegetables, the driven gear 57 rotates and drives the adjusting gear 648 to rotate. At this time, since the threaded end 645 of the lifting shaft 644 cannot be threaded into the inner threaded sleeve 641, the lifting shaft 644 and the adjusting gear 648 are at the upper limit position, thereby keeping the hinge point between the first shaft 561 and the second shaft 562 within the bushing 61, ensuring that the first brush bristles 58 stably brush the dirt off the surface of the fruits and vegetables.

[0075] When the fruits and vegetables are removed from the washing tub 2 after washing, the servo motor 52 drives the drive gear 53 to rotate in the opposite direction. The driven gear 57 then rotates in the opposite direction, which in turn drives the adjusting gear 648 to rotate in the opposite direction. At this time, under the downward pressure of the compression spring 647, the threaded end 645 of the lifting shaft 644 can be threaded into the inner threaded sleeve 641, causing the lifting shaft 644 and the adjusting gear 648 to move downwards. The adjusting plate 649 on the lifting shaft 644 can then drive the driven gear 57 downwards. Simultaneously, when the hinge point between the first shaft 561 and the second shaft 562 moves below the sleeve 61, the servo motor 52 stops rotating in the opposite direction. At this point, the lifting shaft 644 and the adjusting gear 648 are at their lower limit position. Subsequently, under the attraction of the magnet 62, multiple second shafts 562 can be simultaneously driven towards the second... The central axis of the circular plate 54 is tilted to one side, which allows it to grab the fruits and vegetables in the center of the washing tub 2. Then, the lifting cylinder 3 drives the second shaft 562 to move upward and detach from the washing tub 2, thus removing the fruits and vegetables from the washing tub 2. At the same time, after being grabbed by the second shaft 562, the fruits and vegetables remain above the washing tub 2 for a period of time, and the stepper motor 7 continues to rotate. At this time, since the second shaft 562 is tilted and close to the fixed plate 71, the vibrating arm 712 on the side wall of the fixed plate 71 will hit multiple second shafts 562 in sequence as the fixed plate 71 rotates, causing the second shafts 562 to vibrate and swing on the magnet block 62, which helps to quickly drain the water from the surface of the fruits and vegetables. After the water has drained, the experimenter can manually break open the second shaft 562 to remove the fruits and vegetables inside.

[0076] When it is necessary to clean the surface dirt of fruits and vegetables again, the servo motor 52 drives the drive gear 53 to rotate in the forward direction. After the driven gear 57 rotates, it drives the adjusting gear 648 to rotate. Then, the threaded end 645 of the lifting shaft 644 can rotate out from the inner threaded sleeve 641. After the lifting shaft 644 and the adjusting gear 648 move upward, they can drive the driven gear 57 to move upward through the adjusting plate 649. Then, the hinge point between the first shaft 561 and the second shaft 562 moves upward and can enter the bushing 61. The second shaft 562 disengages from the magnet block 62. At the same time, under the limiting action of the bushing 61, the second shaft 562 can return to the vertical position. Then, the first bristles 58 at the lower end of the second shaft 562 can easily enter the cleaning tub 2 to brush the surface dirt of the fruits and vegetables.

Claims

1. A method for detecting heavy metal content in different edible parts of common fruits and vegetables, characterized in that, Includes the following steps: (1) Use a cleaning device to clean the dirt and grime on the surface of fruits and vegetables; (2) Select different edible parts of fruits and vegetables, prepare sample solutions using microwave digestion, and perform blank tests at the same time; (3) Inject the sample solution into the inductively coupled plasma mass spectrometer and measure the signal response values ​​of the analyte and the internal standard. Plot a standard curve with the concentration of the analyte as the abscissa and the ratio of the response signal values ​​of the analyte and the selected internal standard as the ordinate. (4) Inject the blank solution and the sample solution into the inductively coupled plasma mass spectrometer, respectively, and measure the signal response values ​​of the analyte and the internal standard. The concentration of the analyte in the digestion solution is obtained according to the standard curve. (5) Calculation of analytical results: The formula for calculating heavy metal content is as follows: X =(in-c0) V / m In the formula: X — The content of heavy metals, mg / kg; ci — heavy metal concentration in the sample, mg / L; c0 — Concentration of heavy metals in blank sample, mg / L; V—Sample volume at final volume, mL; m—mass of the sample, in grams; The cleaning device includes a base (1), a cleaning bucket (2) set on the base (1) for supplying water and placing the fruits and vegetables to be cleaned, a lifting cylinder (3) set on one side of the base (1), a connecting arm (4) set on the upper end of the lifting cylinder (3), and a washing component (5) set on the end of the connecting arm (4) away from the lifting cylinder (3) for descending and entering the cleaning bucket (2) for washing. The washing assembly (5) includes a first circular plate (51) located at the end of the connecting arm (4) away from the lifting cylinder (3), a servo motor (52) located at the center of the lower surface of the first circular plate (51), a drive gear (53) located on the output shaft of the servo motor (52), a second circular plate (54) located on the lower side of the drive gear (53), a plurality of support arms (55) located between the first circular plate (51) and the second circular plate (54), a plurality of connecting shafts (56) rotatably connected to the periphery of the second circular plate (54), a driven gear (57) located at the upper end of the connecting shaft (56) and meshing with the drive gear (53), and a first brush bristle (58) located on the periphery of the lower end of the connecting shaft (56) for washing the surface of fruits and vegetables. The second circular plate (54) is also provided with a material-collecting component (6) for collecting and draining washed fruits and vegetables. The connecting shaft (56) includes a first shaft (561) whose upper end is fixed to the driven gear (57), and a second shaft (562) whose upper end is hinged to the lower end of the first shaft (561) and whose lower end is used to connect the first bristles (58). The material-collecting component (6) includes a plurality of components arranged around the second circular plate (54) for connecting the first shaft (561) and the second shaft. The shaft sleeve (61) that moves up and down at the hinge point of the body (562), the magnet block (62) provided on the lower surface of the second circular plate (54) and used to attract the second shaft body (562), the attracting slope (63) provided on the magnet block (62) and causing the second shaft body (562) to be inclined toward the central axis of the second circular plate (54), and the adjusting member (64) provided between the second circular plate (54) and the support arm (55) and used to drive the driven gear (57) to move up and down.

2. The method for detecting heavy metal content in different edible parts of common fruits and vegetables according to claim 1, characterized in that: In preparing the sample solution using microwave digestion: Weigh 0.2g-0.5g of solid sample or accurately transfer 1.00mL-3.00mL of liquid sample into the microwave digestion vessel. For samples containing ethanol or carbon dioxide, first heat them on a hot plate at low temperature to remove the ethanol or carbon dioxide. Add 5mL-10mL of nitric acid, cover and let stand for 1 hour or overnight. Tighten the lid and digest according to the standard operating procedure of the microwave digester. After cooling, remove the vessel, slowly open the lid to release the gas, rinse the inner lid with a small amount of water, place the digestion vessel on a temperature-controlled hot plate or in an ultrasonic water bath, heat at 100℃ for 30 minutes or degas ultrasonically for 2-5 minutes, and dilute with water to 25mL or 50mL. Mix well and set aside. At the same time, perform a blank test.

3. The method for detecting heavy metal content in different edible parts of common fruits and vegetables according to claim 1, characterized in that: When the content of each element in the sample is greater than 1 mg / kg, the absolute difference between two independent determinations obtained under repeatability conditions shall not exceed 10% of the arithmetic mean; when the content is less than or equal to 1 mg / kg and greater than 0.1 mg / kg, the absolute difference between two independent determinations obtained under repeatability conditions shall not exceed 15% of the arithmetic mean; when the content is less than or equal to 0.1 mg / kg, the absolute difference between two independent determinations obtained under repeatability conditions shall not exceed 20% of the arithmetic mean.

4. The method for detecting heavy metal content in different edible parts of common fruits and vegetables according to claim 1, characterized in that: The adjusting component (64) includes multiple internal threaded sleeves (641) disposed around the second circular plate (54) and corresponding to the positions of the bushings (61), a fixed arm (642) disposed on the support arm (55), a through hole (643) opened at the end of the fixed arm (642) away from the support arm (55), a lifting shaft (644) passing through the through hole (643), a threaded end (645) disposed at the lower end of the lifting shaft (644) and used for threaded connection in the internal threaded sleeve (641), a connecting plate (646) disposed at the upper end of the lifting shaft (644), a compression spring (647) sleeved on the lifting shaft (644) and with its upper end abutting against the connecting plate (646) and its upper and lower ends abutting against the fixed arm (642), an adjusting gear (648) disposed on the lifting shaft (644) and meshing with the driven gear (57), and an adjusting plate (649) disposed on the lifting shaft (644) and located on the upper and lower sides of the driven gear (57).

5. The method for detecting heavy metal content in different edible parts of common fruits and vegetables according to claim 1, characterized in that: A guide ring surface (611) is provided on the inner wall of the lower end of the bushing (61).

6. The method for detecting heavy metal content in different edible parts of common fruits and vegetables according to claim 1, characterized in that: A stepper motor (7) is provided on the lower side of the second circular plate (54). A fixed disk (71) is connected to the output shaft of the stepper motor (7). A second brush (711) for washing the surface of fruits and vegetables is provided on the periphery of the lower surface of the fixed disk (71). A vibrating arm (712) for impacting the second shaft (562) in an inclined state is provided on the side wall of the fixed disk (71).

7. The method for detecting heavy metal content in different edible parts of common fruits and vegetables according to claim 1, characterized in that: The bottom of the washing tub (2) is provided with a placement platform (8) with its upper surface recessed downwards for placing fruits and vegetables. The periphery of the upper surface of the placement platform (8) is provided with a third bristle (81).

Images