Stable potassium ion selective electrode, preparation method and electrolyte analyzer

Abstract

The present invention belongs to the technical field of electrochemical sensors, solves the technical problems of stability and poor selectivity of potassium ion selective electrodes in the prior art, and provides a potassium ion selective electrode with stability, a preparation method thereof and an electrolyte analyzer. The potassium ion selective electrode includes a potassium ion selective membrane, wherein the potassium ion selective membrane includes a crown ether compound, a fat-soluble salt, a plasticizer and a thermoplastic resin, and the crown ether compound includes two crown ether units connected by a bridging unit, and the crown ether unit is a benzo-15 crown-5 ether, wherein the first group is a cycloalkyl group or an aromatic group, and the second group is an aromatic group or an amide group. The potassium ion selective electrode of the present invention increases the hydrophobicity of the entire molecule through the benzene ring part of benzo-15 crown-5, and has higher selectivity, which helps to improve the overall hydrophobicity of the electrode membrane and enhance the selectivity and service life of the electrode.

Description

[0001] This application is a divisional application of the invention patent application filed on March 27, 2024, with the invention name “Potassium ion selective electrode, preparation method thereof and electrolyte analyzer” and application number 202410357937.8. Technical Field

[0002] The invention relates to the field of electrochemical sensors, and in particular to a stable potassium ion selective electrode, a preparation method thereof and an electrolyte analyzer. Background Art

[0003] Potassium ion (K + ) is one of the most important electrolytes in the human body and other organisms. It plays a key role in maintaining cell function and systemic physiological processes. In human life activities, potassium ions are closely related to nerve activity, kidney health and heart activity. In human sweat, the concentration of potassium ions ranges from 1 to 24 mmol / L, and in human blood, the concentration of potassium ions ranges from 3.8 to 5.4 mmol / L. Abnormal potassium ion concentration can cause many diseases. When the potassium ion concentration increases, it can cause abnormal heartbeat and arrhythmia. When the potassium ion concentration decreases, it may cause muscle weakness and cramps. In severe cases, it can affect heart function, especially in patients with cardiovascular diseases. Therefore, the measurement of potassium ion concentration is of great significance.

[0004] At present, the detection of clinical potassium ion concentration mainly adopts an electrolyte analyzer based on an electrochemical method, and the potassium ion carrier of the potassium ion selective electrode is the core of the electrolyte analyzer to measure potassium ions. In the prior art, a Japanese patent with a publication number of No. 62-70452 discloses a cyclic polyether composition, which is composed of a crown ether compound with 12-crown-4 as a skeleton and a thermoplastic resin. The composition of these compounds is formed into a membrane as a potassium ion selective membrane, but because the cavity diameter of 12-crown-4 crown ether is relatively small relative to the size of potassium ions, it cannot effectively "wrap" potassium ions, resulting in insufficient coordination ability; and 12-crown-4 crown ether has relatively good hydrophilicity, which makes it stable in aqueous solution, but excessive hydrophilicity may cause the mechanical properties of the membrane to decrease, affecting the service life and stability of the electrode. The electrode of the electrolyte analyzer usually needs to be immersed in the sample or standard solution for a long time, so the material used must have good chemical stability;

[0005] Another example is the Chinese patent application number 20130374373.0, which discloses a card-type potassium ion sensor and a preparation method thereof. According to the examples, the potassium ion active carrier used is valinomycin. As a potassium ion active carrier, valinomycin has a low sensitivity and requires a higher potassium ion concentration to achieve reliable detection results. In addition, valinomycin has relatively poor stability and is easily affected by environmental conditions such as light, humidity, temperature, etc., which may cause the performance of the sensor to fluctuate or decrease. The examples also record potential potassium ion active carriers, such as 4-tert-butyl-2,2,14,14-tetraiso-2a,14a,dioxocuproin[4]aryltetraacetic acid tetra-tert-butyl ester, which has a large molecular volume and a complex structure, which may lead to a complicated preparation process and high cost. In addition, its stability under specific environmental conditions needs to be further verified. Summary of the invention

[0006] In view of this, the embodiments of the present invention provide a potassium ion selective electrode, a preparation method thereof and an electrolyte analyzer to solve the problems of poor stability and selectivity of the potassium ion selective electrode in the prior art.

[0007] In a first aspect, an embodiment of the present invention provides a stable potassium ion selective electrode, characterized in that it comprises: a potassium ion selective membrane, wherein the potassium ion selective membrane comprises a crown ether compound, a fat-soluble salt, a plasticizer and a thermoplastic resin;

[0008] The mass percentages of the components in the potassium ion selective membrane are: 0.1% to 5% of the crown ether compound, 0.1% to 5% of the fat-soluble salt, 15% to 30% of the thermoplastic resin, and 60% to 84.8% of the plasticizer;

[0009] Wherein, the structural formula of the crown ether compound is as follows:

[0010]

[0011] In the above structural formula, A is a first group, B is a second group, the first group and the second group are different, the first group is a cycloalkyl group or an aromatic group, the second group is an aromatic group or an amide group, and the potential response value of the crown ether compound to potassium ions is correlated with the first group and the second group;

[0012] The structural formula of the first group is one of the following structural formulas:

[0013]

[0014] In the formula, R1 to R4 are hydrogen atoms or alkyl groups;

[0015] The structural formula of the second group is one of the following structural formulas:

[0016]

[0017] The structural formula of the fat-soluble salt is:

[0018]

[0019] In the above structural formula, X 1 , X 2 , X 3 , X 4 is one or more of a hydrogen atom, a halogen atom, an alkyl group or a halogenated alkyl group, Y1, Y2, Y3 and Y4 are integers of 1-5, and M is an alkali metal.

[0020] Preferably, the structural formula of the first group is:

[0021]

[0022] And the structural formula of the second group is:

[0023]

[0024] Preferably, the fat-soluble salt comprises a potassium ion complexing agent or an organic metal salt.

[0025] Preferably, the thermoplastic resin is at least one of halogenated vinyl monomers or copolymers, styrene, acrylate, methacrylate monomers or copolymers and siloxane polymers or copolymers.

[0026] Preferably, the plasticizer is at least one of phthalate, fatty acid ester and o-nitrophenyl alkyl ether:

[0027] Preferably, the molar ratio of the fat-soluble salt to the crown ether compound is 0.01 to 0.5.

[0028] Preferably, the molar ratio of the fat-soluble salt to the crown ether compound is 0.02 to 0.4.

[0029] Preferably, the potassium ion selective electrode according to claim 5 is characterized in that the molecular weight of the thermoplastic resin is between 1000 and 1000000.

[0030] In a second aspect, an embodiment of the present invention further provides a method for preparing a potassium ion selective electrode as described in the first aspect, the preparation method comprising:

[0031] Dissolving 0.1% to 5% of the crown ether compound, 0.1% to 5% of the fat-soluble salt, 15% to 30% of the thermoplastic resin, and 60% to 84.8% of the plasticizer in a preset organic solvent to obtain a mixed solution, wherein the organic solvent includes tetrahydrofuran, chloroform, 1,2-dichloroethane, dichloromethane, dimethylformamide, dimethylamine oxide, benzene or toluene;

[0032] Applying the mixed solution on the upper surface of a plate, and evaporating the organic solvent to obtain a potassium ion selective membrane;

[0033] The potassium ion selective membrane is fixed on an electrode body to obtain a potassium ion selective electrode.

[0034] In a third aspect, an embodiment of the present invention provides an electrolyte analyzer, comprising the potassium ion selective electrode described in the first aspect.

[0035] In summary, the beneficial effects of the present invention are as follows:

[0036] The potassium ion carrier, potassium ion selective electrode and electrolyte analyzer provided by the embodiments of the present invention improve the stability and selectivity of the potassium ion selective electrode by improving the structure of the crown ether compound, especially by introducing two benzo-15-crown-5 ether units connected by a bridging unit, the size and three-dimensional structure of benzo-15-crown-5 can match the size of potassium ions relatively well, so that it can efficiently form a complex with potassium ions. Compared with smaller crown ethers such as 12-crown-4, benzo-15-crown-5 is more suitable for complexing with potassium ions because its cavity diameter is closer to the optimal matching size of potassium ions, and benzo-15-crown 5 has higher selectivity, thereby reducing cross-response with other ions such as sodium ions;

[0037] Furthermore, the benzene ring part of benzo-15-crown-5 increases the hydrophobicity of the entire molecule, which helps to improve the overall hydrophobicity of the electrode membrane, thereby reducing the interference of water molecules and enhancing the stability and service life of the potassium ion selective electrode. In addition, the chemical structure of benzo-15-crown-5 provides high chemical stability, making the crown ether compound less likely to decompose during storage or use, further improving the stability and reliability of the electrode.

[0038] Finally, the structure of benzo-15crown-5 allows its properties to be further adjusted by introducing functional groups on the benzene ring. The potential response of the crown ether compound to potassium ions is related to the properties of the introduced functional groups, allowing the response range and sensitivity of the electrode to be adjusted by selecting different groups to adapt to different measurement needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings required for use in the embodiment of the present invention will be briefly introduced below. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work, and these are all within the protection scope of the present invention.

[0040] Figure 1 is the structural formula of the crown ether compound of the embodiment of the present invention.

[0041] Figure 2 Is the structural formula of the fat-soluble salt of the embodiment of the present invention.

[0042] Figure 3 The figure is a schematic flow chart of a method for preparing a potassium ion selective electrode according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention.

[0044] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0045] Example 1

[0046] See also Figure 1 ,,The embodiment of the present invention provides a potassium ion carrier, comprising:

[0047] A crown ether compound, wherein the structural formula of the crown ether compound is as follows:

[0048]

[0049] In the above structural formula, A is the first group, B is the second group, the first group and the second group are different, the first group is a cycloalkyl group or an aromatic group, the second group is an aromatic group or an amide group, and the potential response value of the crown ether compound to potassium ions is correlated with the first group and the second group.

[0050] Specifically, it can be seen from the above structural formula that the crown ether compound includes two crown ether units connected by a bridging unit;

[0051] The crown ether unit is benzo-15-crown-5, which is highly selective for potassium ions. The cavity size of benzo-15-crown-5 is suitable for forming a stable complex with potassium ions. This structure allows the crown ether to "capture" potassium ions in the solution, thereby generating a potential change in the electrode that is related to the potassium ion concentration, thereby providing highly selective and sensitive potassium ion detection;

[0052] The two crown ether units are connected by a bridging unit, and the bridging unit can enhance the stability of the overall molecular structure, and can introduce additional functionality or change the physical and chemical properties of the compound, thereby affecting the selectivity and potential response to potassium ions. The bridging unit includes the first group and the second group, and the first group and the second group are different. The potential response value of the crown ether compound to potassium ions is correlated with the first group and the second group. The first group and the second group can be a variety of different chemical structures, such as alkyl chains, aromatic groups or nitrogen-containing groups. If the first group is a cycloalkane group, the introduction of cycloalkane will indirectly affect the coordination environment of potassium ions by changing the three-dimensional structure and flexibility of the compound, and the cycloalkane group increases the hydrophobicity of the compound and reduces the solubility of the compound in an aqueous environment. When the first group and the second group are both aromatic groups, the aromatic groups corresponding to the first group and the second group are different;

[0053] The size and spatial arrangement of the first group A and the second group B can limit the flexibility of the crown ether and reduce the number of its stereoisomers. This conformational restriction helps stabilize a specific form of the crown ether, which has higher selectivity and binding affinity for potassium ions. Appropriate first group A and second group B can make the cavity size and shape of the crown ether compound more suitable for specific ions, such as potassium ions, thereby improving selectivity.

[0054] If the first group is an aromatic group, the aromatic group improves the selectivity for potassium ions through π-π interaction or through an aromatic group with a polar functional group. The aromatic group has a functional group that can form hydrogen bonds, which increases the interaction between potassium ions and compounds, thereby improving the selectivity for potassium ions.

[0055] If the second group is an amide group, its polar carbonyl group (C=O) and amino group (-NH2) can form hydrogen bonds with potassium ions, which has a positive effect on improving potassium ion selectivity. The polarity of the amide group can also provide additional coordination sites with potassium ions; the hydrophobicity of the amide group is weaker than that of the aromatic group because it contains carbonyl and amino groups that can form hydrogen bonds. However, the overall hydrophobicity will be affected by other components in the compound, especially if the number of amide groups is large or the structure is large, which may still increase the overall hydrophobicity.

[0056] As an optional embodiment of the present invention, the structural formula of the first group is one of the following structural formulas:

[0057] First structural formula 1:

[0058] First structural formula 2:

[0059] First structural formula 3:

[0060] First structural formula 4:

[0061] In the formula, R1 to R4 are hydrogen atoms or alkyl groups.

[0062] The group shown in the first structural formula 1 is a cyclohexane group, which increases the hydrophobicity of the entire crown ether compound, thereby reducing the solubility of the compound in an aqueous medium; the cyclohexane group will not directly increase the selectivity of potassium ions because it does not provide a functional group for coordinating with potassium ions, but it can indirectly affect the coordination environment of potassium ions by affecting the overall three-dimensional structure of the compound.

[0063] The group shown in the first structural formula 2 is a naphthalene group, which is a polycyclic aromatic hydrocarbon formed by the fusion of two benzene rings. When R1 and R2 are hydrogen atoms, this structure is naphthalene itself. If R1 and R2 are alkyl groups, then this structure is an alkyl derivative of naphthalene. The aromaticity and rigidity of the naphthalene group help the crown ether compound to form a more stable complex with potassium ions because the aromatic group can provide additional π-π interactions. The naphthalene group, due to its large aromatic area, will significantly increase the overall hydrophobicity of the compound, thereby affecting the solubility of the compound in aqueous solution;

[0064] The group shown in the first structural formula 3 is an anthracene group. Anthracene is a polycyclic aromatic hydrocarbon formed by the fusion of three benzene rings. When R1 to R3 are all hydrogen atoms, this structure is anthracene itself; when R1 to R3 are alkyl groups, this structure is an alkyl derivative of anthracene;

[0065] The aromaticity and large conjugated system of the anthracene group help the crown ether compound to form a more stable complex with potassium ions. The aromatic group can provide additional π-π interactions to stabilize the complex of potassium ions. In addition, the anthracene group, due to its large aromatic area, can significantly increase the overall hydrophobicity of the crown ether compound, thereby enhancing the response and stability of the electrode to potassium ions.

[0066] The group shown in the first structural formula 4 is an azobenzene group, which is a compound containing two benzene rings connected by an azo bond (-N=N-). The introduction of azobenzene will change the three-dimensional configuration of the crown ether, thereby affecting its coordination ability with potassium ions, and it increases the hydrophobicity of the entire compound, thereby reducing its solubility in aqueous media.

[0067] As an optional embodiment of the present invention, the structural formula of the second group is one of the following structural formulas:

[0068] Second structural formula 1:

[0069] Second structural formula 2:

[0070] Second structural formula 3:

[0071] The group shown in the second structural formula 1 is a benzoate structure, including a benzene ring connected to an ester group through an oxygen atom. If the benzoate group is used as the second group of the crown ether compound, it will not directly enhance the selectivity of the crown ether for potassium ions, unless its position or interaction with other functional groups can affect the coordination environment of the crown ether center, but the polarity of the ester group will affect the charge distribution of the entire crown ether compound, thereby indirectly affecting the binding of potassium ions; the presence of the benzene ring will increase the hydrophobicity of the entire compound, and it has a stronger hydrophobicity due to its larger π electron system.

[0072] The group shown in the second structural formula 2 is an anisole group, which is composed of a benzene ring and a methoxy group. Anisole is generally chemically stable and not easily involved in most types of chemical reactions, which helps to enhance the overall stability of the crown ether compound and increase the hydrophobicity of the crown ether compound, thereby affecting the solubility of the compound and its behavior in the biofilm, and contributing to the stability and embeddability of the compound in a hydrophobic environment.

[0073] The group shown in the second structural formula 3 is an amide group, which is a common functional group composed of an amino group (-NH2) and a carbonyl group (C=O). Specifically, this amide group is the simplest form of amide, namely formamide, which is formed by the carbonyl group of formic acid and the amino group.

[0074] If the amide group is used as the B group of the crown ether compound, the amide group can provide an additional coordination site and interact with potassium ions through hydrogen bonds, thereby enhancing the selectivity for potassium ions.

[0075] In a preferred embodiment, the first group is a group shown in the first structural formula 1, and the second group is a group shown in the second structural formula 1. The hydrophobicity of the cyclohexane group contributes to the stability of the compound in a hydrophobic environment, such as in a biofilm or an organic phase. Although the cyclohexane group itself does not provide direct selectivity for potassium ions, by adjusting the spatial structure of the compound, it can indirectly affect the coordination between the crown ether center and potassium ions and enhance the selectivity, and the polarity of the benzoate group indirectly improves the binding affinity of potassium ions by affecting the charge distribution of the crown ether. The specific experimental verification process is described in Example 2 and will not be repeated here.

[0076] In summary, the potassium ion carrier provided by the embodiment of the present invention includes a crown ether compound with a specific structure, wherein the first group A can be a cycloalkyl group or an aromatic group, and the second group B can be an aromatic group or an amide group. By rationally selecting the groups A and B, the three-dimensional structure and electronic properties of the crown ether compound can be adjusted to optimize the coordination interaction with potassium ions. For example, the aromatic group can enhance the coordination through π-π interaction, while the amide group can form a more stable complex with potassium ions through hydrogen bonding;

[0077] The choice of groups A and B can affect the solubility of the entire compound. For example, the cycloalkyl group can increase hydrophobicity, while the amide group can provide hydrophilicity, allowing crown ether compounds to be stable in aqueous environments and effectively operate in hydrophobic environments. The potential response values ​​of crown ether compounds are correlated with the properties of the selected groups A and B, which means that the sensitivity and response speed of the compound to changes in potassium ion concentration can be adjusted by changing these groups. These properties of potassium ion carriers make them suitable for a wide range of applications, from environmental monitoring to biomedical testing, and precise measurement of potassium ions in industrial process control.

[0078] Example 2

[0079] Based on the potassium ion carrier provided in Example 1, Example 2 of the present invention further provides a potassium ion selective electrode, wherein the potassium ion selective electrode comprises a potassium ion selective membrane, and the components of the potassium ion selective membrane include:

[0080] The crown ether compound, fat-soluble salt, thermoplastic resin and plasticizer in Example 1.

[0081] Specifically, the potassium ion selective membrane used in the potassium ion selective electrode is a key component of the electrode because it is directly involved in the selective recognition of potassium ions. The potassium ion selective membrane includes the crown ether compound described in Example 1. The crown ether compound has a specific three-dimensional structure and can form a stable complex with potassium ions. The structure of the crown ether is designed to be highly selective for potassium ions, which means that it can distinguish potassium ions from other similar ions such as sodium ions in the sample;

[0082] Thermoplastic resin provides mechanical strength and structural support for the selective membrane, and is also the matrix of the selective membrane. Crown ether compounds and fat-soluble salts are dispersed in this matrix. Specifically, thermoplastic resins include but are not limited to halogenated vinyl monomers or copolymers, such as polyvinyl chloride (PVC), polyvinyl bromide, polyvinylidene chloride, polytetrafluoroethylene (PTFE), etc.; styrene and its substitutes, such as polystyrene (PS), polychlorostyrene, polybromostyrene, etc.; acrylate or methacrylate monomers or copolymers, such as polymethyl methacrylate (PMMA), polyethyl acrylate, etc.; diene polymers, such as polybutadiene, polyisoprene, and their copolymers with styrene, acrylonitrile, etc.; siloxane polymers or copolymers, such as polydimethylsiloxane (PDMS), etc. When selecting thermoplastic resins for the manufacture of potassium ion selective membranes, key factors to consider include the chemical compatibility of the resin, processing performance, and physical and chemical stability of the final membrane. For example, polyvinyl chloride is widely used to manufacture ion-selective membranes due to its good mechanical properties, chemical stability, and compatibility with plasticizers and other additives. The choice of other resins will depend on the expected application conditions and performance requirements.

[0083] Plasticizers are used to improve the flexibility of the resin so that the film can be more easily handled and applied to the electrode. They can also affect the physical properties of the film, such as permeability and softening point, thereby affecting the performance of the electrode. The plasticizers include but are not limited to phthalates, such as dimethyl phthalate, diethyl phthalate, dioctyl phthalate; fatty acid esters, such as dioctyl adipate, dioctyl pimelate; o-nitrophenyl alkyl ethers, such as o-nitrophenyl octyl ether.

[0084] Lipid-soluble salts play a key role in the function of the electrode because they enhance the selectivity for potassium ions together with the crown ether compound. The lipophilic salts include, but are not limited to, potassium ion complexing agents such as tetrabutylammonium salts, tetraphenylborate, or organometallic salts such as potassium tetrachlorocopper(II) salt ([CuCl4]2-) or potassium tetrachloroplatinum(II) salt ([PtCl4]2-); the selection of appropriate lipophilic salts is essential to ensure the selectivity and sensitivity of the electrode. The choice of salt depends on the target analyte (here potassium ions) and the performance that the electrode is expected to exhibit in a specific measurement environment;

[0085] In a specific embodiment, the potassium ion selective electrode includes, in addition to the potassium ion selective membrane, a reference electrode, a filling solution, a housing, an electrode body, etc. The design of the potassium ion selective electrode may vary depending on its purpose and the required measurement range. These components work together to enable the potassium ion selective electrode to reliably measure the potassium ion concentration in the solution.

[0086] As an optional embodiment of the present invention, see Figure 2 , the structural formula of the fat-soluble salt is:

[0087]

[0088] Where, X 1 , X 2 , X 3 , X 4 is one or more of a hydrogen atom, a halogen atom, an alkyl group or a halogenated alkyl group, Y1, Y2, Y3 and Y4 are integers of 1-5, and M is an alkali metal.

[0089] Specifically, the fat-soluble salt structure shown in the above structure is a general organic metal complex, wherein M represents an alkali metal, which may be lithium, sodium, potassium, etc. X1, X2, X3 and X4 represent different atoms or groups that may be substituted on the benzene ring, which may be hydrogen atoms, halogen atoms (such as chlorine, bromine or iodine), alkyl groups (such as methyl, ethyl, etc.) or halogenated alkyl groups (such as chloromethyl, etc.). Y1, Y2, Y3 and Y4 represent the number of these substituents on the benzene ring, which is an integer from 1 to 5. This type of fat-soluble salt can react with potassium ions (K + ) form complexes to promote the transport of potassium ions in the selective membrane; specific organometallic complexes can be designed to preferentially interact with potassium ions, thereby improving the selectivity of the electrode for potassium ions relative to other ions (such as sodium or lithium); the properties of fat-soluble salts will affect the potential response of the electrode, so the electrode response curve can be adjusted by selecting a suitable organometallic complex.

[0090] The specific chemical properties of this fat-soluble salt (such as solubility, stability, lipophilicity, etc.) will depend on the specific selection of X and Y. For example, the introduction of halogen atoms may increase the hydrophobicity of the compound, while the introduction of alkyl groups may provide certain flexibility and solubility. The choice of alkali metal M (such as potassium) will directly affect its application effect in potassium ion selective electrodes.

[0091] As an optional embodiment of the present invention, the fat-soluble salt includes one or more of potassium tetraphenylborate, potassium tetrakis(4-chlorophenyl)borate, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, potassium tetrakis-(4-tert-butylphenyl)borate, potassium tetrakis-(4-isopropylphenyl)borate, sodium tetrakis(4-isopropylphenyl)borate, lithium tetrakis(p-fluorophenyl)borate or lithium tetrakis(pentafluorophenyl)borate.

[0092] Specifically, potassium tetraphenylborate is a commonly used fat-soluble salt that provides good potassium ion selectivity and a stable potential response;

[0093] Potassium tetrakis(4-chlorophenyl)borate and potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate are fat-soluble salts containing halogens, which increase the hydrophobicity and help improve the performance of the electrode in a hydrophobic environment;

[0094] Sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate and lithium tetrakis(p-fluorophenyl)borate, sodium and lithium salts may be used for special applications, such as when operating within a specific potential window, or under specific ionic strength conditions;

[0095] Potassium tetrakis-(4-tert-butylphenyl)borate and potassium tetrakis-(4-isopropylphenyl)borate, these fat-soluble salts with larger alkyl substituents may increase the flexibility and mechanical stability of the electrode film;

[0096] Salts such as sodium tetrakis(4-isopropylphenyl)borate and lithium tetrakis(pentafluorophenyl)borate can provide specific potential responses and are suitable for electrodes that operate over a wide temperature range or in environments with special requirements.

[0097] The key parameters to consider when selecting these fat-soluble salts include their solubility, stability of the potentiometric response, and synergy with the crown ether compounds. The use of these salts in potassium ion selective electrodes helps to improve the electrode's selectivity for potassium ions while maintaining good potentiometric stability and appropriate mechanical properties.

[0098] As an optional embodiment of the present invention, the mass percentages of the components are: 0.1% to 5% of the crown ether compound, 0.1% to 5% of the fat-soluble salt, 15% to 30% of the thermoplastic resin, and 60% to 84.8% of the plasticizer.

[0099] Specifically, the crown ether compound is the main active component responsible for forming a complex with potassium ions, so its content directly affects the sensitivity and selectivity of the electrode. The proportion of the crown ether compound in the selective membrane is usually low because they are highly active and can provide the required selectivity with a smaller mass percentage. Therefore, the mass percentage of the crown ether compound in the component is 0.1% to 5%;

[0100] The fat-soluble salt enhances the selectivity of the electrode to potassium ions and participates in the formation of potential response, and the content of the fat-soluble salt is also low, because a high concentration may lead to an increase in the background potential of the selective membrane, thereby affecting the sensitivity of the electrode, so the mass percentage of the fat-soluble salt in the component is 0.1% to 0.5%;

[0101] The thermoplastic resin provides a structural matrix for the selective membrane, and its content is sufficient to ensure the mechanical stability and overall strength of the selective membrane. To ensure the processability and final physical properties of the potassium ion selective membrane, the mass percentage of the thermoplastic resin in the component is 15% to 30%;

[0102] Plasticizers are used to improve the flexibility of the resin, making the potassium ion selective membrane easier to process and use. The use of a high proportion of plasticizers makes the potassium ion selective membrane have better flexibility and ductility, and also helps to disperse the crown ether compound and the fat-soluble salt in the thermoplastic resin matrix. In addition, a high content of plasticizer also helps to optimize the electrochemical properties of the electrode, such as potential stability and response time. Therefore, in this embodiment, the mass percentage of the plasticizer in the component is 60% to 84.8%.

[0103] In a specific embodiment, the mass percentage of each component is as follows:

[0104] Crown ether compound: 0.1%

[0105] Fat soluble salts: 0.1%

[0106] Thermoplastic resin: 15%

[0107] Plasticizer: 84.8%

[0108] In this embodiment, the contents of the crown ether compound and the fat-soluble salt are relatively low, and the contents of the thermoplastic resin and the plasticizer are relatively high, which may result in better flexibility and stability of the potassium ion selective membrane, but may sacrifice certain selectivity.

[0109] In another specific embodiment, the mass percentages of the components are as follows:

[0110] Crown ether compounds: 2.5%

[0111] Fat soluble salts: 2.5%

[0112] Thermoplastic resin: 22.5%

[0113] Plasticizer: 72.5%

[0114] In this embodiment, the contents of the components are relatively balanced. The moderate contents of the crown ether compound and the fat-soluble salt can provide good ion selectivity and sensitivity, and the moderate contents of the thermoplastic resin and the plasticizer can provide suitable membrane mechanical properties and stability.

[0115] As an optional embodiment of the present invention, the molar ratio of the fat-soluble salt to the crown ether compound is 0.01 to 0.5.

[0116] In the design of potassium ion selective electrodes, the molar ratio of fat-soluble salt to crown ether compound is one of the key factors affecting the performance of the electrode. This ratio determines the selectivity and sensitivity of the electrode to potassium ions, as well as the service life of the electrode.

[0117] Specifically, the appropriate molar ratio can optimize the electrode's response to changes in potassium ion concentration, making the measurement more sensitive. The appropriate ratio of fat-soluble salts to crown ether compounds can also help improve the stability of the electrode, thereby extending its service life. If the amount of fat-soluble salts exceeds the optimal molar ratio range, the selectivity and sensitivity of the electrode will decrease. This is because too much fat-soluble salt interferes with the potassium ion coordination environment of the crown ether compound, or causes phase separation in the selective membrane, thereby affecting the performance of the electrode.

[0118] Therefore, the molar ratio of the fat-soluble salt to the crown ether compound is 0.01 to 0.5, which can ensure that there are enough fat-soluble salts to combine with the crown ether compound, thereby improving the electrode's selectivity for potassium ions. This means that the electrode can better distinguish potassium ions from other similar ions (such as sodium ions);

[0119] In a preferred embodiment, the molar ratio of the fat-soluble salt to the crown ether compound is 0.02 to 0.4. Excessive fat-soluble salts will interfere with the coordination of the crown ether composition with potassium ions, thereby weakening the specific binding to potassium ions, causing the electrode to respond to other ions, reducing selectivity; the electrode becomes less sensitive to changes in potassium ion concentration, and requires a larger change in ion concentration to detect changes in potential. The decrease in selectivity and sensitivity will accelerate the degradation of electrode performance, requiring more frequent calibration or replacement of the electrode.

[0120] As an optional embodiment of the present invention, the weight of the plasticizer is 30%-300% of the weight of the thermoplastic resin.

[0121] In the formulation of potassium ion selective membranes, plasticizers are added to improve the processing properties of thermoplastic resins and the physical properties of the final product. Plasticizers can lower the glass transition temperature of the resin, making the material softer and more flexible at room temperature.

[0122] The more plasticizer there is, the better the flexibility of the film. This is because the plasticizer molecules are inserted between the resin molecular chains, reducing the intermolecular forces. A higher plasticizer content can reduce the melt viscosity of the resin, making the mixture easier to process into a film at a lower temperature. In an embodiment of the present invention, the weight of the plasticizer is 30%-300% of the thermoplastic resin, allowing the proportion of the plasticizer to be adjusted according to the intended use of the film material. For example, if the film needs to have higher flexibility, a high proportion close to or equal to 300% can be selected; if higher mechanical strength is required, a lower proportion close to 30% can be selected. This range of selection allows the performance of the film to be optimized to suit different application requirements and working conditions.

[0123] When preparing potassium ion selective membranes, the exact ratios of the components need to be optimized through experiments to ensure the best performance of the membrane. These ratios may be adjusted depending on the specific application and the type of raw materials used. The experimental results will determine the best ratio of these components to achieve high selectivity, high sensitivity, good mechanical properties and stable potential response.

[0124] As an optional embodiment of the present invention, the molecular weight of the thermoplastic resin is between 1000 and 1000000;

[0125] Specifically, when selecting a thermoplastic resin for molding into a film, it is critical to consider its molecular weight. Thermoplastic resins with lower molecular weights are generally easier to process and shape because they soften and flow at lower temperatures. Resins with molecular weights in this range, especially those near the lower limit, generally have lower melting points and higher fluidity, making them suitable for film production; as the molecular weight increases, the mechanical strength of the resin generally also increases. A higher molecular weight means there are more intermolecular forces between the chains, which improves the toughness and durability of the material. Resins with molecular weights approaching or exceeding 1,000,000 may exhibit excellent strength and chemical resistance, but may require higher processing temperatures.

[0126] Selecting thermoplastic resins with a molecular weight range of 1,000 to 1,000,000 can find a balance between ease of molding and mechanical strength. This ensures that the resin is easy to handle during the manufacturing process, while the resulting film has sufficient strength to withstand the stresses in actual applications. Thermoplastic resins with a molecular weight between 1,000 and 1,000,000 are selected to ensure that the film is easy to handle and mold during the manufacturing process, while showing good mechanical stability and durability in application. Such a choice helps optimize the overall performance of the film and adapt to the needs of different application scenarios.

[0127] As an optional embodiment of the present invention, in the potassium ion selective membrane, the amount of the crown ether compound is 0.1 to 40 parts by weight for 100 parts by weight of the thermoplastic resin;

[0128] Specifically, when the amount of the crown ether compound is less than 0.1 parts, it may not be sufficient to provide the desired potassium ion selectivity. Crown ether compounds play a key role in the selection membrane, and their main function is to form stable complexes with potassium ions, thereby improving the selectivity for potassium ions. Too low an amount may cause the membrane to have a reduced ability to recognize potassium ions. When the amount of the crown ether compound exceeds 40 parts, it may cause uneven dispersion or even precipitation in the thermoplastic resin matrix. This will destroy the uniformity of the selection membrane and affect its overall performance. Too many crown ether compounds may not be completely dissolved in the resin matrix, resulting in uneven areas in the membrane, which may reduce the performance and reliability of the electrode.

[0129] In a preferred embodiment, for 100 parts by weight of the thermoplastic resin, the amount of the crown ether compound is 0.1 to 10 parts by weight;

[0130] Keeping the amount of crown ether compound within the range of 1-10 parts can ensure that the membrane has good potassium ion selectivity while avoiding unnecessary material waste and cost increase. This range provides the best cost-effectiveness, ensuring the performance of the membrane while taking into account economic benefits.

[0131] In a specific embodiment, if Figure 3 As shown, the preparation method of the potassium ion selective electrode comprises the following steps:

[0132] S1, dissolving 0.1% to 5% of the crown ether compound, 0.1% to 5% of the fat-soluble salt, 15% to 30% of the thermoplastic resin, and 60% to 84.8% of the plasticizer in a preset organic solvent to obtain a mixed solution, wherein the organic solvent includes tetrahydrofuran, chloroform, 1,2-dichloroethane, dichloromethane, dimethylformamide, dimethylamine oxide, benzene or toluene;

[0133] Specifically, according to the ratio, the crown ether compound, fat-soluble salt, thermoplastic resin and plasticizer in the above embodiment are weighed into a container, and an appropriate organic solvent is selected, such as tetrahydrofuran, chloroform, 1,2-dichloroethane, dichloromethane, dimethylformamide, dimethylamine, benzene or toluene. These solvents can provide solubility and operability in the preparation process; the pre-weighed crown ether compound, fat-soluble salt, thermoplastic resin and plasticizer are added to the organic solvent, and then stirred or heated to dissolve until a uniform mixed solution is obtained.

[0134] S2, applying the mixed solution on the upper surface of a flat plate, and evaporating the organic solvent to obtain a potassium ion selective membrane;

[0135] Prepare a flat plate, usually a flat surface made of glass, quartz or polymer material, and ensure that the surface of the plate is clean and free of dust or impurities. Use appropriate coating tools such as a spin coater, a scraper coater, etc. to evenly coat the mixed solution prepared in step S1 on the upper surface of the plate, and place the mixed solution coated on the surface of the plate in a fume hood or a heating plate, and allow the organic solvent to evaporate slowly at a preset temperature until a uniform and continuous film is formed; the preset temperature is determined according to the selected organic solvent and the solvent evaporation rate required in the preparation process, and no specific restrictions are made here; during the experiment, you can try to test at different temperatures, observe the film formation, and select the most suitable temperature conditions.

[0136] S3. Fixing the potassium ion selective membrane on the electrode body to obtain a potassium ion selective electrode.

[0137] Specifically, first prepare a suitable electrode body, the material of which may be glass, ceramic, metal or conductive polymer, ensure that the electrode surface is clean and free of oil or impurities, fix the potassium ion selective membrane prepared in step S2 on the upper surface of the electrode body, and use an adhesive or pressure to fix the membrane on the electrode. If necessary, the membrane fixed on the electrode may be further processed, such as drying, ultraviolet light exposure, etc., to ensure that the membrane is firmly bonded to the electrode.

[0138] Through the above steps, a potassium ion selective electrode with good performance can be successfully prepared for use in applications such as electrolyte analysis.

[0139] In one embodiment, the S3 specifically includes:

[0140] S31, cleaning the surface of the electrode body to remove impurities on the surface;

[0141] Specifically, the electrode surface is thoroughly cleaned with deionized water and an organic solvent (such as ethanol or acetone) to remove impurities, oil stains and oxides on the surface. This is to ensure that the electrode surface is clean, reduce the impact of impurities on subsequent steps, and improve the stability and reliability of the potassium ion selective electrode.

[0142] S32, frosting the surface of the cleaned electrode body so that the surface of the electrode body has a preset roughness;

[0143] Specifically, the electrode surface is lightly frosted using abrasive paper or abrasive rods. Roughening the surface can increase the surface area and adhesion. The frosting can be performed by mechanical grinding, chemical etching or sandblasting to form a tiny concave-convex structure on the electrode surface, which can increase the surface area of ​​the electrode surface, help improve the binding force between the potassium ion selective membrane and the electrode body, and also help to enhance the contact between the electrode and the electrolyte to be tested, thereby improving the sensitivity and response speed of the electrode; and, surface roughening can form a microscopic concave-convex structure that can increase the diffusion path of substances on the electrode surface, thereby promoting the transfer and exchange of substances and improving the sensing performance of the electrode.

[0144] The setting of the preset roughness needs to be determined according to the material of the electrode body, and no specific restrictions are made here. Electrode bodies of different materials have different surface characteristics and properties, so it is necessary to select a suitable preset roughness for a specific material. For example, but not limitation, if the electrode body is a metal material, such as platinum, gold or carbon, a lower preset roughness is usually required because the surfaces of these materials are already relatively smooth. In this case, the preset roughness can be at the micron level or lower. However, if the electrode body is a non-metallic material such as glassy carbon, since its surface itself is relatively rough, a higher preset roughness may be required to ensure good bonding between the potassium ion selective membrane and the electrode body. Therefore, the setting of the preset roughness should be adjusted according to the material properties of the electrode body and the requirements of subsequent process steps to ensure that the potassium ion selective electrode finally prepared has excellent performance and stability.

[0145] S33, immersing the electrode body in an activator for chemical activation treatment, wherein the activator includes one of an acidic activator and an alkaline activator, and / or an oxidant;

[0146] Specifically, the electrode body is immersed in an activator for chemical activation. Chemical activation can improve the chemical properties of the electrode surface, increase the density of active sites, and thus improve the electrochemical performance and stability of the electrode. The type of the activator is determined according to the material of the electrode body and the desired activation effect. Acidic activators such as sulfuric acid and hydrochloric acid are suitable for metal electrode bodies, which can remove surface oxides or other impurities and improve the conductivity and activity of the electrode; alkaline activators such as sodium hydroxide and potassium hydroxide are usually used for non-metallic electrode bodies, which can clean the surface and enhance its activity. Oxidants such as hydrogen peroxide and potassium permanganate can be used for metal and non-metallic electrode bodies, which can oxidize surface substances and change the surface chemical properties, thereby improving the catalytic activity of the electrode. When selecting an activator, factors such as the material of the electrode body, the desired activation effect, and the subsequent use environment need to be considered. In addition, conditions such as the concentration of the activator, the treatment time, and the temperature also need to be adjusted according to the specific situation to achieve the best activation effect.

[0147] Furthermore, activation treatment can change the charge distribution or chemical properties of the electrode surface, making the interaction between the electrode and the ions to be detected more effective and specific, and improving the selectivity and detection performance of the electrode. Through activation treatment, the electrode surface can be made more stable, the unstable factors on the surface can be reduced, the durability and reusability of the electrode can be improved, and the service life of the electrode can be extended.

[0148] S34, cleaning and drying the electrode body after activation by using deionized water and nitrogen;

[0149] The electrode body after activation is cleaned and dried with deionized water and nitrogen. The purpose of this step is to remove the chemicals and impurities that may remain during the activation process, ensure the purity of the electrode surface, and ensure its stability in subsequent use.

[0150] S35, fixing the potassium ion selective membrane on the cleaned and dried electrode body to obtain a potassium ion selective electrode;

[0151] Specifically, the potassium ion selective membrane is fixed on the cleaned and dried electrode body to obtain the potassium ion selective electrode. This step is to closely combine the prepared potassium ion selective membrane with the pretreated electrode body to ensure the stability and reliability of the membrane, thereby improving the performance and service life of the potassium ion selective electrode.

[0152] In one embodiment, the step S35 specifically includes:

[0153] S351, dissolving the self-assembled monolayer modification substance into a corresponding solvent to obtain a modification solvent;

[0154] Specifically, the self-assembled monolayer modifier usually exists in a solid form and needs to be dissolved in an appropriate solvent in order to modify the electrode in the subsequent steps. Dissolving the self-assembled monolayer modifier can cause its molecules to dissociate and disperse in the solution, preparing for modifying the electrode surface. By dissolving the modifier, the concentration and uniformity of the modifier can be better controlled, which helps to achieve the uniformity and stability of the modified layer.

[0155] Wherein, the self-assembled monolayer modifier has a specific functional group, and the specific functional group is determined based on potassium ions and / or the material of the potassium ion selective electrode. Specifically, the selection of the specific functional group should enable the electrode to have good affinity and selectivity for potassium ions. Furthermore, the chemical properties of the functional group should be compatible with the electrode surface and be able to stably bind to the electrode surface under the required conditions;

[0156] For example, but not limitation, for a potassium ion selective electrode, a functional group having a high affinity for potassium ions, such as a crown ether compound, can be selected. The crown ether compound can form a stable coordination complex and form a strong coordination effect with potassium ions, thereby achieving efficient and selective recognition of potassium ions;

[0157] The self-assembled monolayer modifier may also be a sulfur-based compound, which has good metal surface binding and can stably modify the electrode surface. Sulfur-based compounds usually form strong metal-sulfur bonds, and thus can provide higher stability and durability when modifying the electrode surface;

[0158] The self-assembled monolayer modification may also contain functional groups with nucleophilic substitution reaction activity: for example, halogenated alkyl, ester group, etc. These functional groups can form chemical bonds with the electrode surface during the modification process, thereby achieving a stable connection of the modification layer.

[0159] The self-assembled monolayer modifier may also be a functional group with stability and durability: for example, an ether bond, a thioether bond, etc. These functional groups can remain stable under electrochemical conditions and have good tolerance to temperature, solvents and other environmental factors.

[0160] S352, immersing the electrode body in the modification solvent to form a modification layer on the surface of the electrode body;

[0161] Specifically, the electrode body that has been activated is immersed in a modification solvent for a certain period of time. The modification molecules dissolved in the modification solvent will be adsorbed on the electrode surface and self-assembled into a single-layer structure to form a modification layer, thereby giving the electrode specific functions and performance. The formation of the modification layer can enhance the specificity of the electrode, improve its selectivity for specific ions, and enhance the stability and reusability of the electrode.

[0162] S353, fixing the potassium ion selective membrane on the modified layer of the electrode body to obtain the potassium ion selective electrode.

[0163] The pre-prepared potassium ion selective membrane is fixed on the modified electrode surface, usually by coating or pasting the membrane on the electrode surface. Fixing the potassium ion selective membrane can make it fully contact with the modified layer and firmly adhere to the electrode surface to ensure effective ion transfer and detection. Fixing the potassium ion selective membrane can make the electrode have higher selectivity and sensitivity, enhance its application performance in potassium ion analysis, and improve its stability and reusability.

[0164] In another embodiment, the method for preparing the potassium ion selective electrode comprises the following steps:

[0165] S01, mixing a crown ether compound, a thermoplastic resin, a plasticizer and a fat-soluble salt to obtain a mixture;

[0166] S02, heating the mixture to melt at a temperature higher than the softening or melting temperature of the thermoplastic resin;

[0167] S03, using an extrusion or hot pressing method to form the molten mixture into a film-like product to obtain a potassium ion selective membrane;

[0168] S04. Fixing the potassium ion selective membrane on the electrode body to obtain a potassium ion selective electrode.

[0169] In order to test the slope, accuracy and precision of the electrodes assembled from potassium ion selective membranes with different components and ratios, the components were weighed and dissolved in a solvent according to the ratios shown in Table 1 to prepare a sensing membrane solution. The above Table 1 is shown below:

[0170] Table 1 Potassium ion selective membrane component ratio table

[0171]

[0172]

[0173]

[0174] In Table 1, crown ether 1 has a group of the first structural formula 1 as the first group and a group of the second structural formula 1 as the second group; crown ether 2 has a group of the first structural formula 1 as the first group and a group of the second structural formula 2 as the second group; crown ether 3 has a group of the first structural formula 1 as the first group and a group of the second structural formula 3 as the second group;

[0175] Crown ether 4 has the group of the first structural formula 2 as the first group and the group of the second structural formula 1 as the second group; crown ether 5 has the group of the first structural formula 2 as the first group and the group of the second structural formula 2 as the second group; crown ether 6 has the group of the first structural formula 2 as the first group and the group of the second structural formula 3 as the second group;

[0176] Crown ether 7 has a group of the first structural formula 3 as the first group and a group of the second structural formula 1 as the second group; crown ether 8 has a group of the first structural formula 3 as the first group and a group of the second structural formula 2 as the second group; crown ether 9 has a group of the first structural formula 3 as the first group and a group of the second structural formula 3 as the second group;

[0177] Crown ether 10 has a group of the first structural formula 4 as the first group and a group of the second structural formula 1 as the second group; crown ether 11 has a group of the first structural formula 4 as the first group and a group of the second structural formula 2 as the second group; crown ether 12 has a group of the first structural formula 4 as the first group and a group of the second structural formula 3 as the second group;

[0178] In the specific experiment, the steps of preparing the potassium ion sensing membrane include:

[0179] According to the ratio given in Table 1, the crown ether compound, the fat-soluble salt, the thermoplastic resin and the plasticizer are accurately weighed, and the above components are dissolved in the selected organic solvent; under a room temperature fume hood, the solvent is added to the solute; a clean magnetic particle is added, and the container is sealed with a sealing film; the container is placed on a magnetic stirrer, and the solution is stirred at a speed of 500-600rpm for 12 hours to ensure that the components are fully mixed; the stirred solution is poured into a flat dish of polytetrafluoroethylene (PTFE) material to ensure that the solution can evaporate slowly under clean conditions, and the solvent in the solution is allowed to evaporate at room temperature for 48 hours until a membrane is formed, and the membrane obtained after volatilization is the desired potassium ion selective membrane;

[0180] Subsequently, potassium ion selective membranes prepared with different ratios were assembled into electrodes, and the slope, accuracy, and precision were tested. In the process of evaluating the electrode performance of the membrane material prepared by the composition of the present invention, the following equipment and methods were used:

[0181] Test conditions:

[0182] The measurement experiments were carried out in an aqueous solution containing potassium chloride to simulate the behavior of potassium ions in an aqueous environment.

[0183] The test covers 10 -1 M to 10 ^- 5M KCl concentration range to evaluate the performance of the electrode at different concentrations.

[0184] All measurements were performed under constant temperature conditions, with the exact temperature controlled at 25 °C to ensure the consistency and comparability of the experimental data.

[0185] Performance evaluation parameters:

[0186] Slope: Measures the Nernst slope of the electrode response, which is an indicator of the electrode's sensitivity to changes in concentration. Ideally, this value is close to the theoretical value of 59.16 mV / decade.

[0187] Accuracy: Evaluates the deviation between the electrode reading and the actual value of the known concentration, expressed as a percentage. The higher the accuracy, the closer the electrode reading is to the true value.

[0188] Precision: Tests the repeatability of an electrode’s readings. Lower precision values ​​indicate that the electrode has better consistency and reliability.

[0189] The test was carried out according to the above test conditions, and the test results obtained are shown in Table 2;

[0190] Table 2 Test results

[0191]

[0192]

[0193] Tables 1 and 2 list multiple experiments from Experimental Example 1 to Experimental Example 37. Each experimental number corresponds to a different group allocation ratio. By comparing Tables 1 and 2, we can see the effect of different group allocation ratios on electrode performance. The slope represents the sensitivity of the electrode to changes in potassium ion concentration. The theoretical slope predicted by the Nernst equation is about 59.16 mV / decade at 25°C;

[0194] Accuracy indicates the deviation between the electrode reading and the actual potassium ion concentration. Ideally, the accuracy is close to 0%, while the values ​​in the table are usually below 1.5%, which indicates that the electrode prepared by the above potassium ion selective membrane has good accuracy;

[0195] Precision indicates the repeatability of the electrode readings. Lower precision values ​​indicate high repeatability. The values ​​in the table are usually lower than 1.5%, which indicates that the readings of the electrode prepared by the above potassium ion selective membrane are reliable.

[0196] In Table 2, the slope values ​​of Experimental Examples 8, 10, 17, 21, 29, and 30 are 59, which is quite close to the theoretical value. The accuracy and precision of these experimental examples are very low, showing good performance, but the performance of the electrode not only considers the slope, but also the accuracy and precision. The slope of Experimental Example 1 is close to 59.16 mV / decade, and has better accuracy and precision.

[0197] In summary, the potassium ion selective electrode provided in Example 2, the specific crown ether compound is designed to optimize the selectivity for potassium ions, which means that it can more effectively distinguish potassium ions from other ions, such as sodium ions, from the sample. The addition of fat-soluble salts and thermoplastic resins increases the hydrophobicity of the membrane, which helps prevent the membrane from dissolving in an aqueous or water-containing environment, thereby improving the durability and stability of the electrode; due to the stability of the material and the high selectivity for potassium ions, the effective service life of the electrode may be significantly extended, which is particularly important in the case of long-term monitoring or continuous use.

[0198] Example 3

[0199] Based on the potassium ion selective electrode described in Example 2, Example 3 of the present invention further provides an electrolyte analyzer, comprising any of the potassium ion selective electrodes described.

[0200] Since the electrode of Example 2 has high selectivity for potassium ions, it can provide accurate potassium measurement, which is crucial for medical diagnosis and research that requires high-precision monitoring of potassium levels. The design of the electrode allows rapid response to changes in potassium ions, which means that the electrolyte analyzer can monitor changes in potassium ion concentration in the sample in real time; the hydrophobicity and chemical stability of the electrode ensure reliability in long-term continuous monitoring, reducing the need for frequent replacement due to electrode damage or performance degradation.

[0201] In summary, the potassium ion carrier, potassium ion selective electrode and electrolyte analyzer provided in the embodiments of the present invention improve the stability and selectivity of the potassium ion selective electrode by improving the structure of the crown ether compound, especially by introducing two benzo-15-crown-5 ether units connected by a bridging unit, the size and three-dimensional structure of benzo-15-crown-5 can match the size of potassium ions relatively well, so that it can efficiently form a complex with potassium ions, compared with smaller crown ethers such as 12-crown-4, benzo-15-crown-5 is more suitable for complexing with potassium ions because its cavity diameter is closer to the optimal matching size of potassium ions, and benzo-15-crown 5 has higher selectivity, thereby reducing cross-response with other ions such as sodium ions;

[0202] Furthermore, the benzene ring part of benzo-15-crown-5 increases the hydrophobicity of the entire molecule, which helps to improve the overall hydrophobicity of the electrode membrane, thereby reducing the interference of water molecules and enhancing the stability and service life of the potassium ion selective electrode. In addition, the chemical structure of benzo-15-crown-5 provides high chemical stability, making the crown ether compound less likely to decompose during storage or use, further improving the stability and reliability of the electrode.

[0203] Finally, the structure of benzo-15crown-5 allows its properties to be further adjusted by introducing functional groups on the benzene ring. The potential response of the crown ether compound to potassium ions is related to the nature of the introduced functional groups, which may allow the response range and sensitivity of the electrode to be adjusted by selecting different groups to adapt to different measurement needs.

[0204] It should be clear that the present invention is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present invention.

[0205] It should also be noted that the exemplary embodiments mentioned in the present invention describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above steps, that is, the steps can be performed in the order mentioned in the embodiments, or in a different order from the embodiments, or several steps can be performed simultaneously.

[0206] The above is only a specific implementation of the present invention. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the system, module and unit described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be covered within the protection scope of the present invention.

Claims

1. A stable potassium ion selective electrode, characterized in that: include: A potassium ion selective membrane, wherein the potassium ion selective membrane comprises a crown ether compound, a fat-soluble salt, a plasticizer and a thermoplastic resin; The mass percentages of the components in the potassium ion selective membrane are: 0.1% to 5% of the crown ether compound, 0.1% to 5% of the fat-soluble salt, 15% to 30% of the thermoplastic resin, and 60% to 84.8% of the plasticizer; Wherein, the structural formula of the crown ether compound is as follows: In the above structural formula, A is a first group, B is a second group, the first group and the second group are different, and the potential response value of the crown ether compound to potassium ions is correlated with the first group and the second group; The structural formula of the first group is one of the following structural formulas: ， ， ， ； In the formula, R1~R4 are hydrogen atoms or alkyl groups; The structural formula of the second group is one of the following structural formulas: ， ， ； The structural formula of the fat-soluble salt is: In the above structural formula, X1, X2, X3, X4 are one or more of a hydrogen atom, a halogen atom, an alkyl group or a halogenated alkyl group, Y1, Y2, Y3 and Y4 are integers of 1-5, and M is an alkali metal; The thermoplastic resin is at least one of halogenated vinyl monomers or copolymers, styrene, acrylate, methacrylate monomers or copolymers and siloxane polymers or copolymers; The plasticizer is at least one of phthalate, fatty acid ester and o-nitrophenyl alkyl ether.

2. The potassium ion selective electrode according to claim 1, characterized in that The structural formula of the first group is: And the structural formula of the second group is: 。 3. The potassium ion selective electrode according to claim 1, characterized in that The molar ratio of the fat-soluble salt to the crown ether compound is 0.01 to 0.

5.

4. The potassium ion selective electrode according to claim 1, characterized in that The molar ratio of the fat-soluble salt to the crown ether compound is 0.02-0.

4.

5. The potassium ion selective electrode according to claim 1, characterized in that The molecular weight of the thermoplastic resin is between 1,000 and 1,000,000.

6. A method for preparing a potassium ion selective electrode, for preparing the potassium ion selective electrode according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Dissolving 0.1% to 5% of the crown ether compound, 0.1% to 5% of the fat-soluble salt, 15% to 30% of the thermoplastic resin, and 60% to 84.8% of the plasticizer in a preset organic solvent to obtain a mixed solution, wherein the organic solvent includes tetrahydrofuran, chloroform, 1,2-dichloroethane, dichloromethane, dimethylformamide, dimethylamine oxide, benzene or toluene; Applying the mixed solution on the upper surface of a plate, and evaporating the organic solvent to obtain a potassium ion selective membrane; The potassium ion selective membrane is fixed on an electrode body to obtain a potassium ion selective electrode.

7. An electrolyte analyzer, characterized in that: The method comprises the potassium ion selective electrode according to any one of claims 1 to 5.

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