Chromatographic detection method and device for residual pesticides and chemical substances in food

Abstract

The invention discloses a chromatographic detection method and device for residual pesticides and chemical substances in food in the technical field of food detection, and the method comprises the following steps: step 1, crushing the food to be detected, sequentially adding purified water and lipid, and mixing with the crushed food; 2, carrying out water bath heating on the crude mixture, and filtering by using a filter screen to obtain a turbid liquid; step 3, pouring the turbid liquid into a separation pipe, carrying out centrifugal separation, and carrying out condensation treatment; 4, after condensation treatment is completed, supernate in the dissolving solution is extracted, and freezing treatment is conducted; separating the solidified lipid layer on the central tube from the separation tube; step 5, putting the frozen supernatant into a standard solution for chromatographic detection, and putting a solidified block on the uppermost layer of the lipid layer into the standard solution for chromatographic detection to obtain a chromatographic detection report; therefore, the food sample can be quickly purified, and the detection time is shortened.

Description

Technical Field

[0001] The present invention belongs to the technical field of food detection, and in particular relates to a chromatographic detection method and device for residual pesticides and chemical substances in food. Background Art

[0002] In the production process of modern food raw materials, pesticides play an important role in increasing grain production and preventing and controlling food biological disasters, while veterinary drugs also play an important role in improving livestock disease resistance and survival rates in the process of animal husbandry. The widespread use of pesticides and veterinary drugs also brings about food safety issues such as residues.

[0003] Existing food safety testing methods primarily utilize chromatography-mass spectrometry (GC-MS). This technique combines the separation capabilities of chromatography with the qualitative analysis capabilities of mass spectrometry. It can effectively separate residual components in complex samples and rapidly perform qualitative analysis of multiple residual and interfering components, boasting high sensitivity and good reproducibility. However, the detection of multiple pesticide or veterinary drug residues in food still faces challenges such as low residual levels, complex food matrices, and prolonged testing times. Summary of the Invention

[0004] The purpose of the present invention is to provide a chromatographic detection method and device for residual pesticides and chemical substances in food, which can quickly purify food samples to shorten the detection time.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A chromatographic detection method for residual pesticides and chemical substances in food comprises the following steps: Step 1, crushing the food to be tested, and sequentially adding purified water and lipids to the crushed food and mixing them to obtain a crude mixture;

[0007] Step 2: heating the crude mixture in a water bath and filtering it through a filter to obtain a suspension;

[0008] Step 3: Pour the suspension into a separation tube, insert the central tube into the separation tube, fix the separation tube into a separation device and perform centrifugation to obtain upper and lower lipid layers or a dissolved liquid; and simultaneously perform condensation treatment to solidify the upper lipid layer in the separation tube;

[0009] Step 4: After the condensation process is completed, the supernatant in the dissolved liquid is extracted along the central tube by a water pump and discharged into the freezing tank of the separation device for freezing. After the supernatant is extracted, a gap is formed between the lipid layer and the dissolved liquid, and then the solidified lipid layer on the central tube is separated from the separation tube;

[0010] Step 5: Take out the supernatant after freezing treatment and put it into the standard solution of chromatographic detection to obtain a chromatographic detection report; separate the solidified lipid layer in sequence along the intersection of centrifugal separation, and put the solidified block of the uppermost layer of the lipid layer into the standard solution of chromatographic detection to obtain a chromatographic detection report.

[0011] The following beneficial effects are achieved by adopting the above scheme:

[0012] By crushing the food, the pesticides and chemicals in the food are dissolved in pure water and lipids respectively for separation, and then heated in a water bath to accelerate the dissolution of the pesticides and chemicals in the food in pure water or lipids without causing the pesticides and chemicals to volatilize.

[0013] Filtration is used to remove large impurities in food and reduce the processing volume. During the centrifugation process, the difference in freezing point between pure water and lipids is used to cause the lipids to form a lipid layer for solidification, thereby separating the water-soluble substances and fat-soluble substances and performing separate treatments. The difference in centrifugal force is used to remove substances of different specific gravities, making it easier to purify the coarsely filtered liquid again for subsequent chromatographic testing.

[0014] The supernatant in the water body is extracted through the central tube and then condensed to reduce the volatilization of volatile substances in the supernatant, so as to facilitate subsequent chromatographic detection, thereby quickly purifying the food sample matrix and shortening the detection time.

[0015] Furthermore, in step 1, the crude mixture is separated by microwave oscillation.

[0016] Beneficial effect: Microwave oscillation can accelerate the precipitation of substances on the surface of food.

[0017] Furthermore, in step three, the hollow tube is also filled with silica gel or activated carbon, the position of the silica gel corresponds to the dissolving liquid, and the position of the activated carbon corresponds to the lipid layer.

[0018] Beneficial effects: During the centrifugal rotation process, silica gel or activated carbon is facilitated to contact with the object in the hollow tube, the hydrophilic pigment in the dissolved liquid is removed by silica gel, and the lipophilic pigment in the lipid layer is removed by activated carbon, which is convenient for subsequent chromatographic detection.

[0019] Furthermore, a device for removing residual pesticides and chemicals in food comprises a condensation chamber and a separation chamber located within a separation device, wherein the separation chamber is provided with a driving member, a rotating disk, a separation tube and a cover in order from bottom to top;

[0020] The output shaft of the driving member is coaxially connected to the bottom of the turntable. The top of the turntable is fixedly connected to a placement slot (not marked in the figure). The separation tube is placed in the placement slot. A plug body is clamped on the separation tube, and a center tube is fixedly connected to the center of the plug body.

[0021] A suction tube is slidably fitted inside the central tube, and a plurality of openings are formed on the suction tube, the openings being connected to the suction tube. A plurality of openings filled with silica gel or activated carbon are arranged circumferentially around the suction tube, with the silica gel positioned corresponding to the dissolving liquid, and the activated carbon positioned corresponding to the lipid layer. The cover body is rotatably fitted with the top of the separation chamber.

[0022] One end of the suction pipe away from the plug body is connected to a water pump, and the water pump is fixedly connected to the separation device;

[0023] A condensation tank is fixedly connected to the condensation chamber, and a plurality of water outlet pipes are connected to the side wall of the condensation tank. The ends of the water outlet pipes away from the condensation tank are connected to the water pump; a plurality of cooling air pipes are also connected to the side wall of the condensation tank, and the cooling air pipes are located below the cooling air pipes; the ends of the cooling air pipes away from the condensation tank are also connected to the liquid nitrogen tank;

[0024] The condensing chamber is also rotatably equipped with a door, and the condensing chamber is also connected to an exhaust pipe and a recovery pipe, and the exhaust pipe is connected to a first solenoid valve;

[0025] The separation chamber is further provided with a support frame fixedly connected to the separation device, the support frame being circumferentially arranged around the central tube, and a number of transfer pipes being vertically fixedly connected inside the support frame, adjacent transfer pipes being interconnected, one end of the transfer pipe being connected to a recovery pipe, and the transfer pipe being connected to the condensation chamber through the recovery pipe; the other end of the transfer pipe being connected to an exhaust pipe, the end of the exhaust pipe away from the transfer pipe being connected to an air compressor, and the exhaust pipe being connected to a second solenoid valve;

[0026] The transfer pipe is also connected to a plurality of heat exchange pipes, and a plurality of third solenoid valves are arranged at intervals on the transfer pipe. The third solenoid valves are located between adjacent heat exchange pipes.

[0027] The driving part, water pump, air compressor, first solenoid valve, second solenoid valve and third solenoid valve are electrically connected to a processing panel, which controls the driving part, water pump, air compressor, first solenoid valve, second solenoid valve and third solenoid valve to work or stop in sequence based on a preset time sequence.

[0028] Beneficial effects: The driving part drives the central tube on the turntable to rotate, thereby realizing centrifugal separation, thereby separating food impurities from residual pesticides or chemicals in the suspension, and at the same time removing the pigments in the dissolved liquid or lipid layer through silica gel or activated carbon, which is convenient for subsequent chromatographic detection.

[0029] The water pump provides power to allow the supernatant to enter the condensation tank from the suction pipe for freezing, so as to reduce the volatilization of volatile substances in the supernatant. The thawed liquid nitrogen is then transferred to the heat exchange tube for refrigeration, so as to achieve the reuse of resources.

[0030] The control panel controls the driving element, water pump, air compressor, first solenoid valve, second solenoid valve and third solenoid valve to work or stop in a preset time sequence to realize nitrogen circulation in the device, reduce gas leakage, and reduce the volatilization of volatile substances in food, so as to quickly purify the food sample matrix and shorten the detection time.

[0031] Furthermore, the recovery pipe is connected to a one-way valve.

[0032] Beneficial effect: The one-way valve is provided to prevent the air in the condensation chamber from flowing back, thus achieving one-way flow.

[0033] Furthermore, a deformable bottom plate is fixedly connected to the bottom of the freezing tank, a plurality of protrusions are fixedly connected to the top of the bottom plate, an air bag is provided between the bottom plate and the freezing tank, and the air bag is also connected to the air inlet pipe.

[0034] Beneficial effect: External air is injected through the air inlet pipe to expand the air bag, thereby changing the shape of the bottom plate and causing the supernatant liquid subjected to the ice treatment to fall off.

[0035] Furthermore, adjacent protrusions are stepped.

[0036] Beneficial effect: The step-shaped protrusions prevent the solidified supernatant from forming an overall plane, so that the solidified supernatant can be easily removed.

[0037] Furthermore, the heat exchange tubes are arranged in a ring shape with the central tube as the center, and a plurality of heat exchange ports corresponding to the heat exchange tubes are opened on the placement groove.

[0038] Beneficial effect: The annular arrangement of heat exchange tubes and heat exchange ports facilitates careful heat exchange between the nitrogen and air in the heat exchange tubes and the central tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a front view of a device for removing pesticide and chemical residues in food according to an embodiment of the present invention.

[0040] Figure 2 for Figure 1 Cross-sectional view of the separation tube.

[0041] Figure 3 for Figure 1 An enlarged view of part A. DETAILED DESCRIPTION

[0042] The following is further described in detail through specific implementation methods:

[0043] The figure marks in the drawings of the specification include: condensation chamber 1, exhaust pipe 11, first solenoid valve 12, recovery pipe 13, one-way valve 14, separation chamber 2, cover body 21, turntable 22, motor 23, exhaust pipe 24, second solenoid valve 25, support frame 3, cavity 31, separation tube 4, plug body 41, center tube 42, water pump 5, outlet pipe 51, suction pipe 52, transfer pipe 6, heat exchange pipe 61, third solenoid valve 62, freezing tank 7, cold air pipe 71, air bag 72, air inlet pipe 73, bottom plate 74, and bump 75.

[0044] Example 1

[0045] The embodiment is basically as shown in the attached Figures 1 to 3 A chromatographic detection method for residual pesticides and chemicals in food is shown, comprising the following steps: Step 1, crushing the food to be tested, and sequentially adding purified water and lipids to the crushed food, wherein the lipids include but are not limited to benzene, ether, carbon tetrachloride, petroleum ether, etc., to obtain a crude mixture, and separating the crude mixture using microwave oscillation;

[0046] Step 2: heating the crude mixture in a water bath and filtering it through a filter to obtain a suspension;

[0047] For example, by crushing the food, the pesticides and chemicals in the food are dissolved in pure water and lipids respectively for separation, and then heated in a water bath and microwaved to accelerate the dissolution of the pesticides and chemicals in the food in pure water or lipids without volatilizing the pesticides and chemicals. Large impurities in the food are removed by filtering to reduce the processing volume.

[0048] Step 3: Pour the suspension into the separation tube 4, and insert the central tube 42 into the separation tube 4. The hollow tube is also filled with silica gel or activated carbon. The position of the silica gel corresponds to the dissolving liquid, and the position of the activated carbon corresponds to the lipid layer. Then, the separation tube 4 is fixed to the separation device and centrifuged to obtain upper and lower lipid layers or dissolving liquid. At the same time, condensation treatment is performed to solidify the upper lipid layer in the separation tube 4.

[0049] The separation device includes a condensation chamber 1 and a separation chamber 2 located therein. The separation chamber 2 is provided with a driving member (the driving member is a motor 23), a rotating disk 22, a separation tube 4 and a cover 21 in order from bottom to top.

[0050] The output shaft of the driving member is coaxially connected to the bottom of the turntable 22. The top of the turntable 22 is fixedly connected to a placement groove (not shown in the figure). The separation tube 4 is placed in the placement groove. A plug body 41 is clamped on the separation tube 4. The center of the plug body 41 is fixedly connected to a center tube 42.

[0051] A suction tube 52 is slidably fitted within the central tube 42. The suction tube 52 has a plurality of openings formed therein, the openings being in communication with the suction tube 52. A plurality of openings filled with silica gel or activated carbon are arranged circumferentially around the suction tube 52, with the silica gel positioned corresponding to the dissolving liquid and the activated carbon positioned corresponding to the lipid layer. The cover 21 is rotatably fitted to the top of the separation chamber 2.

[0052] One end of the suction pipe 52 away from the plug body 41 is connected to the water pump 5, and the water pump 5 is fixedly connected to the separation device;

[0053] A condensation tank is fixedly connected to the condensation chamber 1. A plurality of water outlet pipes 51 are connected to the side wall of the condensation tank. The ends of the water outlet pipes 51 away from the condensation tank are connected to the water pump 5. A plurality of cooling air pipes 71 are also connected to the side wall of the condensation tank. The cooling air pipes 71 are located below the cooling air pipes 51. The ends of the cooling air pipes 71 away from the condensation tank are also connected to the liquid nitrogen tank.

[0054] The condensing chamber 1 is also rotatably equipped with a door. The condensing chamber 1 is also connected to an exhaust pipe 11 and a recovery pipe 13. The exhaust pipe 11 is connected to a first solenoid valve 12.

[0055] A support frame 3 fixedly connected to the separation device is further provided in the separation chamber 2. The support frame 3 is circumferentially arranged around the central tube 42. A number of transfer pipes 6 are vertically fixedly connected in the support frame 3. Adjacent transfer pipes 6 are connected to each other. One end of the transfer pipe 6 is connected to a recovery pipe 13. The transfer pipe 6 is connected to the condensation chamber 1 through the recovery pipe 13, and the recovery pipe 13 is also connected to a one-way valve 14. The one-way valve 14 can only allow the air in the condensation chamber 1 to flow in one direction into the transfer pipe 6; the other end of the transfer pipe 6 is connected to an exhaust pipe 11. The end of the exhaust pipe 11 away from the transfer pipe 6 is connected to an air compressor, and the exhaust pipe 11 is connected to a second solenoid valve 25;

[0056] For example, the support frame 3 provides installation space for the heat exchange tube 61 , and the support frame 3 can reduce the possibility of cold air leakage, thereby improving the cooling effect.

[0057] The transfer pipe 6 is also connected to a plurality of heat exchange pipes 61. The heat exchange pipes 61 are arranged in a ring with the central pipe 42 as the center. The placement groove is also provided with a plurality of heat exchange ports corresponding to the heat exchange pipes 61. The transfer pipe 6 is also provided with a plurality of third solenoid valves 62 arranged at intervals. The third solenoid valves 62 are located between adjacent heat exchange pipes 61.

[0058] The driving part, water pump 5, air compressor, first solenoid valve 12, second solenoid valve 25 and third solenoid valve 62 are electrically connected to a processing panel, which controls the driving part, water pump 5, air compressor, first solenoid valve 12, second solenoid valve 25 and third solenoid valve 62 to work or stop in sequence based on a preset time sequence.

[0059] For example, during the centrifugation process, silica gel or activated carbon can come into contact with the object in the hollow tube, and the hydrophilic pigment in the dissolved solution can be removed by silica gel, while the lipophilic pigment in the lipid layer can be removed by activated carbon, so as to facilitate subsequent chromatographic detection.

[0060] By utilizing the difference in freezing points between pure water and lipids, the lipids are solidified into a lipid layer. Water pump 5 then provides power to move the supernatant from suction pipe 52 into a condensation tank for freezing, reducing the volatilization of volatile substances in the supernatant. Thawed liquid nitrogen is then transferred to heat exchange pipe 61 for refrigeration, achieving resource reuse. Water-soluble and fat-soluble substances are then separated and processed separately. The difference in centrifugal force is utilized to remove substances of different specific gravities, facilitating further purification of the coarsely filtered liquid for subsequent chromatographic analysis.

[0061] Step 4: After the condensation process is completed, the supernatant in the dissolved liquid is extracted along the central tube 42 by the water pump 5 and discharged into the freezing tank 7 of the separation device for freezing. After the supernatant is extracted, a gap is formed between the lipid layer and the dissolved liquid, and then the solidified lipid layer on the central tube 42 is separated from the separation tube 4.

[0062] Step 5: Take out the supernatant after freezing treatment and put it into the standard solution of chromatographic detection to obtain a chromatographic detection report; separate the solidified lipid layer in sequence along the intersection of centrifugal separation, and put the solidified block of the uppermost layer of the lipid layer into the standard solution of chromatographic detection to obtain a chromatographic detection report.

[0063] For example, the supernatant in the water body is extracted through the central tube 42 and then condensed to reduce the volatilization of volatile substances in the supernatant, and the substances in the lipid layer are also separated, so that the water-soluble or fat-soluble pesticides and chemicals in the food can be purified separately to facilitate subsequent chromatographic detection, thereby quickly purifying the food sample matrix to shorten the detection time.

[0064] Example 2

[0065] The difference from the above embodiment is that a deformable bottom plate 74 is fixedly connected to the bottom of the freezing tank 7, a number of protrusions 75 are fixedly connected to the top of the bottom plate 74, and adjacent protrusions 75 are stepped. An air bag 72 is provided between the bottom plate 74 and the freezing tank 7, and the air bag 72 is also connected to the air intake pipe 73.

[0066] The specific implementation process is as follows: when the supernatant solidifies on the bottom plate 74, external air is injected through the air inlet pipe 73 to expand the air bag 72, thereby changing the shape of the bottom plate 74 to cause the frozen supernatant to fall off, so that the solidified supernatant can be taken out.

[0067] The above is only an embodiment of the present invention, and common knowledge such as the specific structure and / or characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A chromatographic detection method for residual pesticides and chemical substances in food, characterized in that: The following steps are involved: Step 1: crush the food to be tested, and then add purified water and lipids to the crushed food in sequence to obtain a crude mixture; Step 2: heating the crude mixture in a water bath and filtering it through a filter to obtain a suspension; Step 3: Pour the suspension into a separation tube, insert the central tube into the separation tube, fix the separation tube into a separation device and perform centrifugation to obtain upper and lower lipid layers or a dissolved liquid; and simultaneously perform condensation treatment to solidify the upper lipid layer in the separation tube; Step 4: After the condensation process is completed, the supernatant in the dissolved liquid is extracted along the central tube by a water pump and discharged into the freezing tank of the separation device for freezing. After the supernatant is extracted, a gap is formed between the lipid layer and the dissolved liquid, and then the solidified lipid layer on the central tube is separated from the separation tube; Step 5: Take out the supernatant after freezing treatment and put it into the standard solution of chromatographic detection to obtain a chromatographic detection report; separate the solidified lipid layer in sequence along the intersection of centrifugal separation, and put the solidified block of the uppermost layer of the lipid layer into the standard solution of chromatographic detection to obtain a chromatographic detection report.

2. The chromatographic detection method for residual pesticides and chemical substances in food according to claim 1, characterized in that: In step 1, the crude mixture is separated by microwave oscillation.

3. The chromatographic detection method for residual pesticides and chemical substances in food according to claim 1, characterized in that: In step three, the hollow tube is further filled with silica gel or activated carbon, the position of the silica gel corresponds to the dissolving liquid, and the position of the activated carbon corresponds to the lipid layer.

4. A device for removing pesticide and chemical residues in food, characterized in that: The device for the chromatographic detection method of residual pesticides and chemical substances in food according to any one of claims 1 to 3 comprises a condensation chamber and a separation chamber located within the separation device, wherein the separation chamber is provided with a driving member, a turntable, a separation tube, and a cover in order from bottom to top; The output shaft of the driving member is coaxially connected to the bottom of the turntable. The top of the turntable is fixedly connected to a placement groove. The separation tube is placed in the placement groove. A plug body is clamped on the separation tube. The center of the plug body is fixedly connected to a center tube. A suction tube is slidably fitted inside the central tube, and a plurality of openings are formed on the suction tube, the openings being connected to the suction tube. A plurality of openings filled with silica gel or activated carbon are arranged circumferentially around the suction tube, with the silica gel positioned corresponding to the dissolving liquid, and the activated carbon positioned corresponding to the lipid layer. The cover body is rotatably fitted with the top of the separation chamber. One end of the suction pipe away from the plug body is connected to a water pump, and the water pump is fixedly connected to the separation device; A condensation tank is fixedly connected to the condensation chamber, and a plurality of water outlet pipes are connected to the side wall of the condensation tank. The ends of the water outlet pipes away from the condensation tank are connected to the water pump; a plurality of cooling air pipes are also connected to the side wall of the condensation tank, and the cooling air pipes are located below the cooling air pipes; the ends of the cooling air pipes away from the condensation tank are also connected to the liquid nitrogen tank; The condensing chamber is also rotatably equipped with a door, and the condensing chamber is also connected to an exhaust pipe and a recovery pipe, and the exhaust pipe is connected to a first solenoid valve; The separation chamber is further provided with a support frame fixedly connected to the separation device, the support frame being circumferentially arranged around the central tube, and a number of transfer pipes being vertically fixedly connected inside the support frame, adjacent transfer pipes being interconnected, one end of the transfer pipe being connected to a recovery pipe, and the transfer pipe being connected to the condensation chamber through the recovery pipe; the other end of the transfer pipe being connected to an exhaust pipe, the end of the exhaust pipe away from the transfer pipe being connected to an air compressor, and the exhaust pipe being connected to a second solenoid valve; The transfer pipe is also connected to a plurality of heat exchange pipes, and a plurality of third solenoid valves are arranged at intervals on the transfer pipe. The third solenoid valves are located between adjacent heat exchange pipes. The driving part, water pump, air compressor, first solenoid valve, second solenoid valve and third solenoid valve are electrically connected to a processing panel, which controls the driving part, water pump, air compressor, first solenoid valve, second solenoid valve and third solenoid valve to work or stop in sequence based on a preset time sequence.

5. The device for removing pesticide and chemical residues in food according to claim 4, characterized in that: The recovery pipe is also connected with a one-way valve.

6. The device for removing pesticide and chemical residues in food according to claim 4, characterized in that: A deformable bottom plate is fixedly connected to the bottom of the freezing tank, a plurality of protrusions are fixedly connected to the top of the bottom plate, an air bag is arranged between the bottom plate and the freezing tank, and the air bag is also connected to the air inlet pipe.

7. The device for removing pesticide and chemical residues in food according to claim 6, characterized in that: There are steps between adjacent protrusions.

8. The device for removing pesticide and chemical residues in food according to claim 4, characterized in that: The heat exchange tubes are arranged in a ring shape with the central tube as the center, and a plurality of heat exchange ports corresponding to the heat exchange tubes are opened on the placement groove.

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