Electrochemical blood ammonia sensor based on conductivity detection, preparation method and detection method

Abstract

The invention discloses an electrochemical blood ammonia sensor based on conductivity detection, which comprises an electrode support body and a conductivity electrode embedded in the electrode support body, and the conductivity electrode is connected with the electrode support body through insulation paste; the electrode lead is connected with the conductivity electrode; the insulating material is used for fixing the electrode lead; an electrode electrolyte, an electrode cap and an ammonia gas selective permeable membrane are arranged at the top end of the conductivity electrode; the electrode electrolyte is arranged between the conductivity electrode and the ammonia gas selective permeable membrane, and the electrode cap is used for fixing the electrode membrane on the electrode support body. The invention also discloses a corresponding preparation method and a detection method, and the detection method comprises the following steps: dropwise adding a sample to the surface of the electrode membrane, and converting NH4 < + > in the sample into NH3 through the ammonium ion conversion reagent; the generated NH3 reaches the electrode electrolyte through the electrode diaphragm to cause the change of the conductivity of the electrolyte, and the concentration of the blood ammonia is quantitatively measured by measuring the change of the conductivity of the electrolyte based on the functional relationship between the change of the conductivity of the electrolyte and the concentration of the blood ammonia in the sample.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical blood ammonia detection, and in particular to an electrochemical blood ammonia sensor based on conductivity detection, and a preparation and detection method thereof. Background Art

[0002] Blood ammonia is mainly produced in the intestines. In the liver, ammonia combines with glutamate to form glutamine, which is then excreted through the kidneys. Therefore, blood ammonia concentration is closely related to the function of the intestines, liver, and kidneys. As a form of ammonia in the human body, abnormal levels of blood ammonia are closely related to a variety of diseases, such as liver disease, kidney disease, and amino acid metabolism disorders. Therefore, accurate and rapid detection of blood ammonia levels is crucial for the diagnosis and treatment of diseases.

[0003] Biochemical tests for blood ammonia include:

[0004] (1) Direct colorimetric method: venous blood is collected at the bedside, protein is precipitated with tungstate, and then color is developed with phenol-hypochlorite. The ammonia content is calculated by reference to the standard. If the experimental conditions are strictly controlled, this analytical method can meet clinical requirements.

[0005] (2) Glutamate dehydrogenase rate method: When there is sufficient α-ketoglutarate and NADPH in plasma, ammonia is converted into glutamate by glutamate dehydrogenase and NADPH is consumed. The rate of decrease of NADPH is proportional to the plasma ammonia concentration.

[0006] (3) Dry chemical direct colorimetric method: venous blood is collected at the bedside, and the color is developed using Berthe lot (phenol-hypochlorite) reagent. The ammonia content is calculated with reference to the standard.

[0007] These methods are affected by factors such as specific experimental conditions, equipment, and experimenters, and have certain limitations and are not suitable for rapid clinical testing. Therefore, there is an urgent need for an instant testing method that can further shorten the measurement time, simplify the operating procedures, and reduce the required sample volume.

[0008] In clinical practice, biochemical analyzers and blood ammonia detectors are often used to measure blood ammonia.

[0009] 1. Biochemical Analyzer

[0010] (1) Measurement principle: The measurement principle of blood ammonia detection by biochemical analyzer is mainly based on enzyme kinetics. This method uses a specific enzyme reaction to determine the concentration of blood ammonia. In this process, blood ammonia reacts with α-ketoglutarate to produce glutamate under the catalysis of glutamate dehydrogenase and the participation of β-NADPH (reduced coenzyme II) and H+. This reaction will lead to the oxidation of β-NADPH, and its absorbance at 340nm will change. This change is proportional to the concentration of blood ammonia, so the concentration of blood ammonia can be determined by measuring the change in absorbance.

[0011] (2) The sample processing and testing process of the biochemical analyzer for testing blood ammonia mainly includes the following steps:

[0012] (a) Sample collection: Select an appropriate blood collection needle and blood collection tube (usually an ammonia-free blood collection tube), and collect a blood sample from the patient according to standard blood collection procedures.

[0013] (b) Sample processing: The collected blood samples should be sent for testing immediately to avoid long-term storage that may cause changes in blood ammonia concentration. During the testing process, the samples should be kept on ice.

[0014] (c) Sample preparation: To avoid ammonia released by red blood cells causing an increase in ammonia in the sample, the sample needs to be centrifuged as quickly as possible.

[0015] The minimum sample volume required for the biochemical analyzer is 1 mL; the test time is within 1 hour; therefore, there are the following disadvantages:

[0016] The determination process takes a long time, the operation is complicated, the reagent cost is high, and a large amount of sample is required. If the sample is not handled properly, the ammonia concentration in the sample will increase.

[0017] 2. Blood ammonia detector:

[0018] (1) Measurement principle: It uses micro-diffusion dry method technology to perform high-precision detection on whole blood;

[0019] (2) Figure 1 As shown in the figure, the sample processing and testing process of the blood ammonia detector for testing blood ammonia mainly includes the following steps:

[0020] (a) Add sample to the sample diffusion layer;

[0021] (b) NH4 in the spacer layer sample + becomes NH3;

[0022] (c) ammonia gas reacts with the reagent layer to cause a color change reaction;

[0023] (d) Measure the chromaticity of the reflected light.

[0024] Sample volume: 20 μL whole blood, blood is collected from the ear

[0025] Test time: about 3 minutes and 20 seconds per test

[0026] Disadvantages: The measurement process takes a long time, the operation is complicated, the reagent cost is high, and the reagent layer has poor anti-interference ability.

[0027] In summary, the existing technology has problems such as bulky equipment, high price, high false positive rate, long time required for the determination process, complicated operation, high reagent cost, and large sample volume required. Therefore, it is required to further shorten the determination time, simplify the operation process, reduce the required sample volume, and realize instant blood ammonia detection. Summary of the invention

[0028] The purpose of the present invention is to provide an electrochemical blood ammonia sensor based on conductivity detection, and its preparation and detection method. The measurement principle of the electrochemical blood ammonia sensor is mainly based on electrochemical conductivity detection technology. When the sample is dripped onto the surface of the electrode membrane, the NH4 + The ammonium ion conversion reagent on the electrode membrane converts NH4 + It turns into NH3; the generated NH3 reaches the electrode electrolyte through the electrode membrane composed of ammonia selective permeable membrane. After NH3 enters the electrode, it will cause the change of electrolyte conductivity. The change process of electrolyte conductivity can be detected by conductivity electrode. The electrical signal has a certain relationship with the concentration of blood ammonia in the sample. Therefore, the concentration of blood ammonia can be quantitatively determined by measuring the change of conductivity.

[0029] The first aspect of the present invention is to provide an electrochemical blood ammonia sensor based on conductivity detection, comprising:

[0030] An electrode support and a conductivity electrode embedded in the electrode support, wherein the conductivity electrode is connected to the electrode support by an insulating glue; the electrochemical blood ammonia sensor also comprises an electrode wire connected to the conductivity electrode and an insulating material fixing the electrode wire; the top of the conductivity electrode is provided with an electrode electrolyte, an electrode cap and an ammonia selective permeable membrane; the electrode electrolyte is placed between the conductivity electrode and the ammonia selective permeable membrane, and the electrode cap is used to fix the electrode membrane composed of the ammonia selective permeable membrane on the electrode support.

[0031] Preferably, the conductive electrode is made of a material with good conductivity, and the material with good conductivity is any one of gold, platinum, silver, a carbon rod or an alloy.

[0032] Preferably, the electrode support is an organic polymer material with good insulation properties, and the organic polymer material with good insulation properties is any one of ABS, PPS, PP, PVC and POM.

[0033] Preferably, the insulating glue is epoxy resin glue.

[0034] Preferably, the electrode electrolyte contains at least one or more of hydrochloric acid, phosphoric acid, sulfuric acid, phosphate solution and pure water.

[0035] Preferably, the ammonia selective permeable membrane is made of a specific polymer material; the specific polymer material has a specific structure and properties, which enables it to selectively allow ammonia molecules to pass through in a mixed gas, while other gas molecules are blocked; the ammonia selective permeable membrane is selected from any one of polytetrafluoroethylene, polyethylene and polyamide.

[0036] Preferably, the ammonia selective permeable membrane further comprises an ammonium ion conversion reagent, and the pH value of the sample is adjusted by the ammonium ion conversion reagent to convert NH4 + into NH3; the ammonium ion conversion reagent includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate.

[0037] Preferably, the connection portion between the electrode cap and the electrode support is provided with threads, and the electrode cap fixes the electrode membrane composed of the ammonia selective permeable membrane on the electrode support via the threads.

[0038] The second aspect of the present invention is to provide a method for preparing an electrochemical blood ammonia sensor based on conductivity detection, comprising:

[0039] S1, preparing an electrode support, comprising: processing the electrode support according to a predetermined structure;

[0040] S2, preparing a conductivity electrode, comprising:

[0041] S21, preparing two conductivity electrode rods according to a predetermined conductivity electrode structure;

[0042] S22, welding the wires to the bottom ends of the conductivity electrode rods respectively;

[0043] S23, embedding the conductive electrode rod welded with the wire into the electrode support, and then adding insulating glue for sealing;

[0044] S3, preparing an electrode cap, including: processing the electrode cap according to a predetermined structure;

[0045] S4, preparing an electrode selective permeable membrane, comprising:

[0046] After the polytetrafluoroethylene membrane is subjected to low-temperature plasma surface treatment, a pH adjusting material and chitosan oligosaccharide are mixed in a certain proportion, and then dropped on the surface of the polytetrafluoroethylene membrane, and dried to form the ammonia selective permeable membrane;

[0047] S5, assembling electrodes, including: injecting the electrolyte into the cavity of the electrode support frame at the top of the conductivity electrode, covering the ammonia selective permeable membrane, covering the electrode cap, tightening the thread between the electrode cap and the electrode support, and fixing the electrode membrane composed of the ammonia selective permeable membrane on the electrode support through the thread.

[0048] The third aspect of the present invention is to provide a detection method of an electrochemical blood ammonia sensor based on conductivity detection, which is implemented based on electrochemical principles and includes:

[0049] The sample is dripped onto the surface of the electrode membrane composed of the ammonia selective permeable membrane, and the NH4 + Converted to NH3;

[0050] The generated NH3 reaches the electrode electrolyte through the electrode membrane, and after NH3 enters the electrode, it causes a change in the conductivity of the electrode electrolyte;

[0051] The conductivity electrode detects the change in electrolyte conductivity before and after ammonia enters the electrode electrolyte. The change in electrolyte conductivity has a fixed functional relationship with the blood ammonia concentration in the sample. The blood ammonia concentration is quantitatively determined by measuring the change in electrolyte conductivity based on the fixed functional relationship.

[0052] Beneficial effects of the method and system of the present invention:

[0053] (1) Short measurement time and high efficiency: During the in vitro blood ammonia detection process, the sensor can obtain the test results of sample blood ammonia in 1 minute, thus solving the problem of long time and complicated operation required during the measurement process;

[0054] (2) The sensor is reusable, and only the electrolyte and the electrode membrane need to be replaced during measurement;

[0055] (3) The sensor has low manufacturing cost and is easy to use, which can solve the problems of bulky equipment, expensive price and high reagent cost in the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the related technologies, the drawings required for use in the specific embodiments or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0057] Figure 1 It is a schematic diagram of the measurement process and detection principle of the blood ammonia detector in the prior art;

[0058] Figure 2 A schematic diagram of the structure of an electrochemical blood ammonia sensor based on conductivity detection according to a preferred embodiment of the present invention;

[0059] Figure 3 A schematic diagram of the structure of an electrode support prepared according to a preferred embodiment of the present invention;

[0060] Figure 4 A schematic diagram of the structure of a conductivity electrode rod prepared according to a preferred embodiment of the present invention;

[0061] Figure 5 A schematic diagram of the structure of the electrode cap prepared according to a preferred embodiment of the present invention;

[0062] Figure 6 A schematic diagram of the structure of the electrode selective permeable membrane prepared according to a preferred embodiment of the present invention;

[0063] Figure 7 A linear graph of conductivity and blood ammonia gradient provided according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0064] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0066] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] A first aspect of the present embodiment is to provide an electrochemical blood ammonia sensor based on conductivity detection, comprising:

[0068] An electrode support and a conductivity electrode embedded in the electrode support, wherein the conductivity electrode is connected to the electrode support by an insulating glue; the electrochemical blood ammonia sensor also comprises an electrode wire connected to the conductivity electrode and an insulating material fixing the electrode wire; the top of the conductivity electrode is provided with an electrode electrolyte, an electrode cap and an ammonia selective permeable membrane; the electrode electrolyte is placed between the conductivity electrode and the ammonia selective permeable membrane, the connection part between the electrode cap and the electrode support is provided with a thread, and the electrode cap fixes the electrode diaphragm composed of the ammonia selective permeable membrane on the electrode support.

[0069] As a preferred embodiment, the conductivity electrode is usually made of a material with good conductivity, and the material is selected from any one of gold, platinum, silver, carbon rod or alloy. Carbon rod is preferably used as the conductivity electrode material based on comprehensive cost and other factors. The shape and size of the conductivity electrode are processed according to actual requirements.

[0070] As a preferred embodiment, the electrode support is an organic polymer material with good insulation properties, and the electrode support is selected from any one of ABS, PPS, PP, PVC and POM. Preferably, this embodiment uses PPS as the electrode support material, and after processing according to actual requirements, the conductive electrode connected to the electrode wire is embedded in the electrode support and fixed by insulating glue.

[0071] As a preferred implementation, the insulating adhesive is epoxy resin adhesive.

[0072] As a preferred embodiment, the electrode electrolyte is a key part connecting the two conductivity electrodes, and the electrode electrolyte contains at least one or more of hydrochloric acid, phosphoric acid, sulfuric acid, phosphate solution and pure water.

[0073] As a preferred embodiment, the ammonia selective permeable membrane is made of a specific polymer material; the specific polymer material has a specific structure and properties, which enables it to selectively allow ammonia molecules to pass through in a mixed gas, while other gas molecules are blocked; the ammonia selective permeable membrane is selected from one of polymer materials such as polytetrafluoroethylene (PTFE), polyethylene (PE) and polyamide (PA), and most preferably, polytetrafluoroethylene (PTFE) is selected as the material of the ammonia selective permeable membrane.

[0074] As a preferred embodiment, the ammonia selective permeable membrane comprises an ammonium ion conversion reagent. In the embodiment of the present invention, the pH value of the sample is adjusted by the ammonium ion conversion reagent to convert NH4 +The ammonium ion conversion reagent includes a variety of different suitable materials, including, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and one or more other suitable pH adjustment materials. Preferably, the ammonium ion conversion reagent is sodium hydroxide.

[0075] As a preferred embodiment, after the polytetrafluoroethylene (PTFE) membrane is treated with low-temperature plasma surface treatment, the pH adjusting material and chitosan oligosaccharide are mixed in a certain proportion, and then dripped on the surface of the polytetrafluoroethylene membrane, and dried to form the ammonia selective permeable membrane; after the sample is dripped on the electrode surface, it is contacted with the ammonium ion conversion reagent so that the pH value of the sample is above 13, and NH4 + The generated NH3 reaches the electrolyte through the electrode membrane composed of the ammonia selective permeable membrane. After NH3 enters the electrode, it will cause the change of the electrolyte conductivity.

[0076] As a preferred embodiment, the connection portion between the electrode cap and the electrode support is provided with threads, and the electrode cap fixes the electrode membrane composed of the ammonia selective permeable membrane on the electrode support through the threads.

[0077] A second aspect of the present embodiment is to provide a method for preparing an electrochemical blood ammonia sensor based on conductivity detection, comprising:

[0078] S1, preparing an electrode support, comprising: processing the electrode support according to a predetermined structure;

[0079] S2, preparing a conductivity electrode, comprising:

[0080] S21, preparing two conductivity electrode rods according to a predetermined conductivity electrode structure;

[0081] S22, welding the wires to the bottom ends of the conductivity electrode rods respectively;

[0082] S23, embedding the conductive electrode rod welded with the wire into the electrode support, and then adding insulating glue for sealing;

[0083] S3, preparing an electrode cap, including: processing the electrode cap according to a predetermined structure;

[0084] S4, preparing an electrode selective permeable membrane, comprising:

[0085] After the polytetrafluoroethylene membrane is subjected to low-temperature plasma surface treatment, a pH adjusting material and chitosan oligosaccharide are mixed in a certain proportion, and then dropped on the surface of the polytetrafluoroethylene membrane, and dried to form the ammonia selective permeable membrane;

[0086] S5, assembling electrodes, including: injecting the electrolyte into the cavity of the electrode support frame at the top of the conductivity electrode, covering the ammonia selective permeable membrane, covering the electrode cap, tightening the thread between the electrode cap and the electrode support, and fixing the electrode membrane composed of the ammonia selective permeable membrane on the electrode support through the thread.

[0087] The third aspect of the present embodiment is to provide a detection method of an electrochemical blood ammonia sensor based on conductivity detection, and the detection method is implemented based on the electrochemical principle, including:

[0088] The sample is dripped onto the surface of the electrode membrane composed of the ammonia selective permeable membrane, and the NH4 + Converted to NH3;

[0089] The generated NH3 reaches the electrode electrolyte through the electrode membrane, and after NH3 enters the electrode, it causes a change in the conductivity of the electrode electrolyte;

[0090] The conductivity electrode detects the change in electrolyte conductivity before and after ammonia enters the electrode electrolyte. The change in electrolyte conductivity has a fixed functional relationship with the blood ammonia concentration in the sample. The blood ammonia concentration is quantitatively determined by measuring the change in electrolyte conductivity based on the fixed functional relationship.

[0091] Application examples:

[0092] See also Figure 2 The blood ammonia sensor of the embodiment of the present invention comprises an electrode support 5 and conductivity electrodes 4 and 8 embedded in the support, wherein the conductivity electrodes 4 and 8 are connected to the electrode support 5 by insulating glue; the sensor further comprises wires 7 and 9 connecting the conductivity electrodes 4 and 8 and insulating material 6 fixing the electrode wires; the top of the conductivity electrode is provided with an electrolyte 3, an electrode cap 2 and an ammonia selective permeable membrane 1. The electrolyte 3 is placed between the conductivity electrode and the ammonia selective permeable membrane 1, the connection part between the electrode cap 2 and the electrode support 5 is provided with a thread, and the electrode cap 2 fixes the ammonia selective permeable membrane 1 on the electrode body.

[0093] The electrodes are prepared according to the following steps:

[0094] (1) Preparation of electrode support 5

[0095] According to Figure 3 The structure of the electrode support 5 shown is processed.

[0096] (2) Preparation of Conductivity Electrodes 4 and 8

[0097] 1) According to Figure 4The structure shown is processed into conductive electrode rods 4 and 8, and conductors 7 and 9 are welded to the bottom ends of the conductive electrode rods respectively.

[0098] 2) The conductive electrode rod with the welding wire is embedded into the electrode support 5, and then epoxy resin glue is added for sealing.

[0099] (3) Preparation of electrode cap 2

[0100] According to Figure 5 The structure of the electrode cap shown is processed.

[0101] (4) Preparation of electrode selective permeable membrane 1

[0102] After the polytetrafluoroethylene membrane is treated with low-temperature plasma, 1MM sodium hydroxide is mixed with 2% chitosan oligosaccharide, and then dropped on the polytetrafluoroethylene surface and dried at 40 degrees to form an ammonia selective permeable membrane. Figure 6 shown.

[0103] (5) Assembling electrodes

[0104] The electrolyte 3 is injected into the cavity of the electrode support 5 at the top of the conductivity electrode to cover the electrode selective permeable membrane 1, and then the electrode cap 2 is put on, and the thread between the electrode cap 2 and the electrode support 5 is tightened to fix the selective permeable membrane 1.

[0105] Example 2

[0106] The blood ammonia sensor of Example 1 was used to measure the blood ammonia of the sample. As the sample, venous whole blood with adjusted ammonium ion concentration (ammonium ion concentration: 10, 20, 30, 50, 100, 200, 300, 400, 500umo l / L) was used. Under a 25°C environment, 20uL of the sample was provided to the selective permeable membrane of the blood ammonia sensor, and the change in conductivity before and after the sample was added was recorded. The electrode selective permeable membrane and the electrolyte were replaced before each sample measurement, such as Figure 7 A linear plot of conductivity and blood ammonia gradient is shown.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrochemical blood ammonia sensor based on conductivity detection, characterized in that: include: An electrode support and a conductivity electrode embedded in the electrode support, wherein the conductivity electrode is connected to the electrode support by an insulating glue; the electrochemical blood ammonia sensor also comprises an electrode wire connected to the conductivity electrode and an insulating material fixing the electrode wire; the top of the conductivity electrode is provided with an electrode electrolyte, an electrode cap and an ammonia selective permeable membrane; the electrode electrolyte is placed between the conductivity electrode and the ammonia selective permeable membrane, and the electrode cap is used to fix the electrode membrane composed of the ammonia selective permeable membrane on the electrode support.

2. An electrochemical blood ammonia sensor based on conductivity detection according to claim 1, characterized in that: The conductive electrode is made of a material with good conductivity, and the material with good conductivity is any one of gold, platinum, silver, a carbon rod or an alloy.

3. An electrochemical blood ammonia sensor based on conductivity detection according to claim 2, characterized in that: The electrode support is an organic polymer material with good insulation properties, and the organic polymer material with good insulation properties is any one of ABS, PPS, PP, PVC and POM.

4. The electrochemical blood ammonia sensor based on conductivity detection according to claim 3, characterized in that: The insulating glue is epoxy resin glue.

5. The electrochemical blood ammonia sensor based on conductivity detection according to claim 4, characterized in that: The electrode electrolyte comprises at least one or more of hydrochloric acid, phosphoric acid, sulfuric acid, a phosphate solution and pure water.

6. The electrochemical blood ammonia sensor based on conductivity detection according to claim 5, characterized in that: The ammonia selective permeable membrane is made of a specific polymer material; the specific polymer material has a specific structure and property, which enables it to selectively allow ammonia molecules to pass through in a mixed gas, while other gas molecules are blocked; the ammonia selective permeable membrane is selected from any one of polytetrafluoroethylene, polyethylene and polyamide.

7. The electrochemical blood ammonia sensor based on conductivity detection according to claim 6, characterized in that: The ammonia selective permeable membrane also includes an ammonium ion conversion reagent, through which the pH value of the sample is adjusted to convert NH4 + into NH3; the ammonium ion conversion reagent includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate.

8. The electrochemical blood ammonia sensor based on conductivity detection according to claim 7, characterized in that: The connection portion between the electrode cap and the electrode support is provided with threads, and the electrode cap fixes the electrode membrane composed of the ammonia selective permeable membrane on the electrode support through the threads.

9. A method for preparing an electrochemical blood ammonia sensor based on conductivity detection according to claim 8, characterized in that: include: S1, preparing an electrode support, comprising: processing the electrode support according to a predetermined structure; S2, preparing a conductivity electrode, comprising: S21, preparing two conductivity electrode rods according to a predetermined conductivity electrode structure; S22, welding the wires to the bottom ends of the conductivity electrode rods respectively; S23, embedding the conductive electrode rod welded with the wire into the electrode support, and then adding insulating glue for sealing; S3, preparing an electrode cap, including: processing the electrode cap according to a predetermined structure; S4, preparing an electrode selective permeable membrane, comprising: After the polytetrafluoroethylene membrane is subjected to low-temperature plasma surface treatment, a pH adjusting material and chitosan oligosaccharide are mixed in a certain proportion, and then dropped on the surface of the polytetrafluoroethylene membrane, and dried to form the ammonia selective permeable membrane; S5, assembling electrodes, including: injecting the electrolyte into the cavity of the electrode support frame at the top of the conductivity electrode, covering the ammonia selective permeable membrane, covering the electrode cap, tightening the thread between the electrode cap and the electrode support, and fixing the electrode membrane composed of the ammonia selective permeable membrane on the electrode support through the thread.

10. A detection method of an electrochemical blood ammonia sensor based on conductivity detection according to any one of claims 1 to 8, characterized in that: The detection method is implemented based on the electrochemical principle, including: The sample is dripped onto the surface of the electrode membrane composed of the ammonia selective permeable membrane, and the NH4 + Converted to NH3; The generated NH3 reaches the electrode electrolyte through the electrode membrane, and after NH3 enters the electrode, it causes a change in the conductivity of the electrode electrolyte; The conductivity electrode detects the change in electrolyte conductivity before and after ammonia enters the electrode electrolyte. The change in electrolyte conductivity has a fixed functional relationship with the blood ammonia concentration in the sample. The blood ammonia concentration is quantitatively determined by measuring the change in electrolyte conductivity based on the fixed functional relationship.

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