Electrochemical Potential Sensing Electrode

Abstract

The invention discloses an electrochemical potential sensing electrode. The electrochemical potential sensing electrode provided by the invention comprises: an indicator electrode, a reference electrode, and a conductive gel arranged between the indicator electrode and the reference electrode. The invention adopts the conductive gel to realize the function of liquid-free junction, and the electrolyte seepage is small and stable, so that the potential sensing electrode is not easy to be blocked, and the contamination of the sample to be tested is avoided, and maintenance and maintenance are free.

Description

Technical Field

[0001] The invention relates to the field of composite electrodes, in particular to an electrochemical potential sensing electrode. Background Art

[0002] The potential signal of the composite pH electrode is established by the glass film ball and the reference solution through the permeation ring and is output by the indicator electrode and the reference electrode. It can be measured by a precision voltmeter after high resistance / low resistance impedance conversion. The factors that affect the stability of pH value are often the penetration method of the reference solution and the composition of the glass film ball.

[0003] In the past, the reference solution penetration methods included point-shaped ceramic sand cores and Teflon rings. The former has a small penetration surface, is easy to clog, and is sensitive to the flow rate of the water sample, which will lead to poor reference solution penetration and unstable reference potential as the water flow rate changes. The latter has a short penetration path, is not pressure-resistant, and is easily reversely penetrated, causing the reference solution to be diluted and contaminated, thereby causing the reference potential to drift. Both will affect the stability and accuracy of pH measurement. At the same time, the common pH electrode sensitive membrane materials are SiO2, CaO and Na2O (where the mass ratio of SiO2, CaO and Na2O is 0.72: (0.06~0.08): (0.20~0.22)), which has the disadvantages of large sodium difference, poor chemical stability, and easy crystallization. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention provides an electrochemical potential sensing electrode.

[0005] In order to achieve the above object, the present invention provides an electrochemical potential sensing electrode, which includes: an indicator electrode, a reference electrode, and a conductive gel arranged between the indicator electrode and the reference electrode.

[0006] The conductive gel is selected from at least one of polyacrylic acid compounds, polyacrylamide compounds, polyhydroxymethacrylate compounds, poly-N-vinyl pyrrolidone compounds and polyaniline compounds;

[0007] Preferably, it is at least one selected from the group consisting of polyethylene oxide, polyethylene glycol, polyvinyl alcohol, poly-N-isopropylacrylamide, polyacrylamide and polyhydroxyethyl methacrylate.

[0008] Wherein, the indicator electrode comprises:

[0009] Inner electrode shell;

[0010] A sensitive bulb connected to one end of the inner electrode shell;

[0011] The internal reference electrode is inserted from the inner electrode shell and extends into the sensitive bulb.

[0012] The raw materials for preparing the sensitive bulb include silicon dioxide and lithium oxide;

[0013] Preferably, the preparation raw materials further include at least one of titanium oxide, vanadium oxide, tantalum oxide, zirconium oxide, germanium oxide and rare earth oxide.

[0014] More preferably, the rare earth oxide is selected from at least one of lanthanum oxide, praseodymium oxide and cerium oxide.

[0015] Wherein, the reference electrode comprises:

[0016] An outer electrode shell, one end of which is connected to the sensitive bulb;

[0017] A liquid junction hole, which is a reference liquid junction, is provided on the outer electrode shell;

[0018] a spiral tube disposed around the indicator electrode;

[0019] an external reference electrode, which is inserted from one end of the spiral tube;

[0020] The spiral tube is liquid-connected to the sand core, which is connected to the other end of the spiral tube.

[0021] Among them, there are two liquid junction holes.

[0022] Preferably, two liquid contact holes are symmetrically opened below the outer electrode shell;

[0023] Preferably, the diameter of the liquid contact hole is 0.5-2 mm.

[0024] The two ends of the spiral tube are arranged in a straight line shape, and the rest of the spiral tube is arranged in a spiral shape.

[0025] Preferably, the number of turns of the spiral tube is 4 to 15;

[0026] Preferably, the inner diameter of the spiral tube is 1.5 to 3.5 mm, the wall thickness is 0.1 to 0.5 mm, and the pitch is 1 to 5 mm.

[0027] The electrochemical potential sensing electrode of the present invention has the following beneficial effects:

[0028] (1) The present invention utilizes a conductive gel filled between the indicator electrode and the reference electrode to achieve a liquid-free junction function, and the electrolyte leakage is small and stable, so that the potential sensing electrode is not easily blocked, thereby avoiding contamination of the sample to be tested, and is maintenance-free;

[0029] (2) The electrochemical potential sensing electrode of the present invention can reduce the sodium difference, improve the crystallization performance and reduce the expansion coefficient, thereby making the potential sensing electrode have higher chemical stability;

[0030] (3) The electrochemical potential sensing electrode of the present invention has a stable half-cell potential. The half-cell potential is in contact with the measured medium through a salt bridge, so that the half-cell potential has good stability and can prevent the influence of various external substances on it;

[0031] (4) The electrochemical potential sensing electrode of the present invention can effectively avoid the defects of conventional liquid junction structure blockage and large liquid junction potential difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of an electrochemical potential sensing electrode provided by the present invention;

[0033] The following is an explanation of the reference numerals:

[0034] 1-sensitive bulb, 2-inner electrode shell, 3-inner reference electrode, 4-outer electrode shell, 5-liquid junction hole, 6-spiral tube liquid junction sand core, 7-spiral tube, 8-outer reference electrode. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0036] It should be noted that, in this article, the terms "include", "comprises" or any other variations 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 includes 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 sentence "includes..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0037] First, Figure 1 The structure diagram of an electrochemical potential sensing electrode provided by the present invention is shown in FIG. Specifically, the electrochemical potential sensing electrode of the present invention comprises: an indicator electrode, a reference electrode, and a conductive gel disposed between the indicator electrode and the reference electrode.

[0038] In traditional technology, the external reference solution penetration mainly adopts clay, capillary, sand core, salt crystallization, precipitation (AgCl, AgS, etc.), etc., but these forms are easy to block the liquid junction, causing electrode poisoning and failure, and the external reference solution is easy to evaporate and crystallize.

[0039] The polymer conductive gel is a multi-component system composed of polymers with a three-dimensional cross-linked network structure and low-molecular medium. Its main chain or side chain contains ion dissociation, polar or hydrophobic groups, which can produce reversible, discontinuous (or continuous) volume changes in response to changes in solvent composition, temperature, pH value, light, electric field, magnetic field, etc. Therefore, the swelling or expansion properties of the polymer conductive gel network can be affected by controlling its microstructure and morphology, so that the conductive gel can respond sensitively to weak external stimuli. Once the external stimulus disappears, the conductive gel will automatically return to a stable state with low internal energy.

[0040] Therefore, in order to solve the problems existing in the prior art, the present invention adopts a conductive gel of a high molecular polymer to improve the balance of the reference electrode in different solutions, wherein the conductive gel does not contain silver ions, does not react to the measured medium with serious pollution such as sulfur, and the junction potential of the external reference solution is very stable, which can improve the measurement accuracy. At the same time, the external reference solution in the reference electrode has a small and stable exudation amount, does not pollute the measured medium, and eliminates maintenance and servicing work.

[0041] In a preferred embodiment of the present invention, the conductive gel is at least one selected from the group consisting of polyacrylic acid compounds, polyacrylamide compounds, polyhydroxymethacrylate compounds, poly-N-vinyl pyrrolidone compounds and polyaniline compounds.

[0042] Among them, the monomers of acrylic acid and its salts contain both vinyl and carboxylic acid functional groups, and the molecules have the functions of polymerization, cross-linking and modification, and are easy to copolymerize and cross-link with other monomers or themselves to form gels.

[0043] In addition to the properties of general gels, polyhydroxyisomethacrylate gels are also non-antigenic, non-irritating and have good suturing ability.

[0044] Poly (N-vinyl pyrrolidone) is a non-ionic water-soluble polymer compound that is soluble in water and most organic solvents and has low toxicity and good biocompatibility.

[0045] Polyaniline in a doped state is a good conductive polymer material with readily available raw materials, simple synthesis method and high chemical stability.

[0046] Preferably, the conductive gel is at least one selected from polyethylene oxide, polyethylene glycol, polyvinyl alcohol, poly-N-isopropylacrylamide, polyacrylamide and polyhydroxyethyl methacrylate.

[0047] Among them, poly (N-isopropylacrylamide) gel belongs to the low-temperature melting type. It can show obvious hydrophilic and hydrophobic changes in a small temperature range, and its lower limit of critical dissolution temperature is around 32°C.

[0048] Among them, polyacrylamide is stable, colorless and transparent, easy to observe, and can even be directly measured using a measuring instrument; and it has no ionic side groups and will not easily react with the measured medium. Therefore, polyacrylamide is preferably used as the conductive gel in the present invention.

[0049] However, the polymer network of most polymer conductive gels contains ionized groups bonded by chemical bonds. Therefore, such conductive gels are often prepared by chemical or physical crosslinking of polymers with ionic groups. In the present invention, polyacrylamide is a conventional existing preparation method, which can include the following steps, for example:

[0050] Step 1, mixing and dissolving potassium chloride, acrylamide, and methylene acrylamide (wherein the mass ratio of potassium chloride, acrylamide, and methylene acrylamide is 12:7:1);

[0051] Step 2, preparing ammonium persulfate solution;

[0052] Step 3: Mix the solution of step 1 and the solution of step 2, perform polymerization reaction, and post-treat to obtain a transparent colloid.

[0053] like Figure 1 As shown, the indicator electrode of the present invention mainly includes: a sensitive bulb 1, an inner electrode shell 2 and an inner reference electrode 3.

[0054] Among them, the sensitive bulb 1 is connected to one end of the inner electrode shell.

[0055] Among them, when a solution with pH>10 is measured with an ordinary glass electrode, the electrode potential and the solution pH value will deviate from the linear relationship, and the measured pH value will be lower than the actual value. This phenomenon is called "alkali difference" or "sodium difference". The reason for this is that in a strong alkaline solution, the hydrogen ion concentration is very low, and the presence of a large number of sodium ions in the solution increases the tendency of sodium ions to enter the silicate lattice of the glass electrode. In addition to being determined by the hydrogen ion concentration (activity) in the silica gel layer and the solution, the generation of the interphase potential difference also increases the interphase potential generated by the diffusion of sodium ions in the two phases.

[0056] In the traditional process, the materials of the sensitive bulb are SiO2, CaO and Na2O (where the mass ratio of SiO2, CaO and Na2O is 0.72: (0.06-0.08): (0.20-0.22)). However, the sensitive bulb has a large sodium difference, poor chemical stability and is easy to crystallize.

[0057] It is found that when the material of the sensitive bulb 1 is SiO2, CaO and Li2O (wherein the mass ratio of SiO2, CaO and Li2O is 7.2:1:1.8), the sodium difference of the sensitive bulb is significantly reduced, which indicates that the addition of lithium oxide Li2O can reduce the sodium difference. In addition, lithium oxide Li2O can also reduce electrode resistance, improve crystallization performance and reduce the expansion coefficient of the sensitive bulb.

[0058] Therefore, the raw materials for preparing the sensitive bulb 1 of the present invention include silicon dioxide and lithium oxide.

[0059] Studies have shown that titanium oxide TiO2, vanadium oxide V2O5 or rare earth oxides, such as lanthanum oxide La2O3, praseodymium oxide Pr2O3 or cerium oxide CeO2, can reduce electrode resistance.

[0060] Zirconium oxide ZrO2 or rare earth oxides, such as La2O3, can improve crystallization performance;

[0061] Rare earth oxides, such as La2O3, can increase the softening point temperature, reduce the expansion coefficient, and improve water resistance;

[0062] Tantalum oxide Ta2O5, germanium oxide GeO2 or rare earth oxides, such as La2O3, can improve the processing performance and strength of the sensitive bulb.

[0063] Therefore, the preparation raw material also includes at least one of titanium oxide, vanadium oxide, tantalum oxide, zirconium oxide, germanium oxide and rare earth oxide, and the rare earth oxide is selected from at least one of lanthanum oxide, praseodymium oxide and cerium oxide.

[0064] It can be seen that lithium oxide Li2O and lanthanum oxide La2O3 can improve various properties of the sensitive bulb 1. Therefore, in order to improve the performance of the sensitive bulb 1, in a preferred embodiment of the present invention, the raw materials for preparing the sensitive bulb 1 include silicon dioxide, lithium oxide, titanium oxide and lanthanum oxide.

[0065] For example, the mass ratio of silicon dioxide, lanthanum oxide, lithium oxide and titanium oxide in the sensitive bulb 1 is (11-17): (2-7): (0.9-2): 1. Experiments have shown that under this mass ratio, the performance indicators of the potential sensing electrode, such as sodium difference, internal resistance and electrode slope, are optimal.

[0066] In order to ensure convenient storage of the potential sensing electrode and stable use in a smaller container, in a preferred embodiment of the present invention, the diameter of the sensitive bulb 1 is 7-9 mm, and the film thickness is 0.04-0.06 mm. More preferably, the diameter is 8±0.2 mm, and the film thickness is 0.05±0.005 mm.

[0067] At the same time, in order to protect the sensitive bulb 1 and prevent it from breaking or being damaged, a protective cover can be provided on the outside of the sensitive bulb 1. The protective cover is hollow and is sleeved on the connection between the reference electrode and the sensitive bulb 1, and a recess is provided at the connection for clamping and preventing separation.

[0068] According to the present invention, the raw material of the inner electrode shell 2 should have the same expansion coefficient as the sensitive bulb, and its resistance should be larger than that of the sensitive bulb and should be insensitive to pH value.

[0069] Therefore, the raw materials for preparing the inner electrode shell 2 include silicon dioxide, boron oxide B2O3, sodium oxide Na2O and potassium oxide K2O;

[0070] For example, the mass ratio of silicon dioxide, boron oxide, sodium oxide and potassium oxide in the inner electrode shell 2 is (10-16): (2-6): (1-3): 1. The glass tube with this mass ratio has a thermal expansion coefficient similar to that of the sensitive bulb, is not prone to expansion and cracking when sintered with the sensitive bulb, and is not sensitive to pH. Among them, the internal reference electrode 3 is inserted from the inner electrode shell 2 and extends into the sensitive bulb 1.

[0071] In a preferred embodiment of the present invention, the internal reference electrode is selected from a silver-silver chloride electrode (Ag / AgCl electrode), a saturated calomel electrode or a hydrogen electrode.

[0072] For example, since the Ag / AgCl electrode has very low solubility, extremely high stability and reversibility in a high-temperature and high-pressure aqueous solution system, and the electrode surface is well protected even in the presence of hydrogen, these characteristics are unmatched by other electrodes. Therefore, the present invention preferably uses the Ag / AgCl electrode as the internal reference electrode.

[0073] According to the present invention, when the silver-silver chloride electrode is used as the internal reference electrode, the solution of potassium chloride and two kinds of phosphates is the internal reference solution, wherein the ratio of the two kinds of phosphates plays a role in regulating the pH zero potential of the internal solution. Preferably, a saturated aqueous solution of potassium chloride containing potassium dihydrogen phosphate and disodium hydrogen phosphate is the internal reference solution, and more preferably, the mass ratio of potassium chloride, sodium dihydrogen phosphate and disodium hydrogen phosphate is (70-80): (10-15): (10-15). The reason for selecting the saturated aqueous solution of potassium chloride is to keep consistent with the composition of the external reference solution, enhance the ionic strength of the internal reference solution, and maintain the stability of the internal reference solution. At the same time, the two kinds of phosphates just form a buffer system, which ensures that the substances in the internal reference solution system will not react chemically with each other, and further maintain the stability of the internal reference solution.

[0074] like Figure 1 As shown, the reference electrode of the present invention comprises: an outer electrode shell 4, a liquid connection hole 5, a spiral tube liquid connection sand core 6, a spiral tube 7 and an external reference electrode 8.

[0075] One end of the outer electrode shell 4 is connected to the sensitive bulb 1 , and the other end is parallel to one end of the inner electrode shell 2 .

[0076] In a preferred embodiment of the present invention, the material of the outer electrode shell 4 is the same as that of the inner electrode shell 2 to ensure the stability of the potential sensing electrode.

[0077] Preferably, the outer electrode shell 4 is connected to the junction of the sensitive bulb 1 and the inner electrode shell 2 and is closed. This arrangement avoids the use of a sealing ring and can extend the service life of the potential sensing electrode.

[0078] The liquid junction hole 5 is a reference liquid junction and is provided on the outer electrode shell 4 .

[0079] In order to keep the hydraulic pressure difference of the external reference solution and make the measurement result more accurate, in a preferred embodiment of the present invention, there are two liquid connection holes 5 . Preferably, the two liquid connection holes 5 are symmetrically opened below the outer electrode shell 4 .

[0080] The diameter of the liquid junction aperture 5 affects the stability of the potential difference between the liquid junction interfaces. If the diameter of the liquid junction aperture 5 is too large, the conductive gel will easily overflow, resulting in poor stability or contamination of the measured medium during measurement. If the diameter of the liquid junction aperture 5 is too small, the salt bridge cannot be well formed between the external reference solution, the conductive gel and the measured medium, resulting in a large error in the measurement result. Therefore, in a preferred embodiment of the present invention, the diameter of the liquid junction aperture 5 is 0.5 to 2 mm, preferably 0.9 to 1.1 mm.

[0081] The spiral tube 7 is arranged around the indicator electrode.

[0082] According to the present invention, the spiral tube 7 is an independent reference tube having a stable half-cell potential. It is in contact with the measured medium through a salt bridge, so that the half-cell potential has good stability and can prevent the influence of various external substances.

[0083] Exemplarily, the material of the spiral tube 7 is the same as that of the inner electrode shell 2. The spiral tube 7 is tightly wound around the outer side of the rear end of the inner electrode shell 2.

[0084] In order to better insert the external reference electrode 8 and the spiral tube liquid-connected sand core 6, in a preferred embodiment of the present invention, the two ends of the spiral tube 7 are set to be straight, and the rest is spiral.

[0085] Preferably, the number of turns of the spiral tube 7 is 4-15, preferably 8-12.

[0086] Preferably, the inner diameter of the spiral tube 7 is 1.5-3.5 mm, the wall thickness is 0.1-0.5 mm, and the pitch is 1-5 mm. The outer diameter of the spiral tube 7 is 6-10 mm. More preferably, the inner diameter is 2-3 mm, the wall thickness is 0.1-0.3 mm, and the pitch is 2-4 mm. The outer diameter of the spiral tube 7 is 7-8 mm.

[0087] In the present invention, the size of the spiral tube 7 is determined by the gap between the inner electrode shell 2 and the outer electrode shell 4, and the inner diameter is preferably 2 mm. The number of turns, pitch and inner diameter of the spiral tube are designed to achieve the purpose of extending the length of the external reference electrode as much as possible within the limited space of the outer electrode shell 4, and to slow down the pollution performance of external chemical mass transfer. The potential sensing electrode of the present invention has a long service life and can maintain the stability of the electrode after being used for 2-3 years.

[0088] An external reference electrode 8 is inserted from one end of the spiral tube 7 .

[0089] For example, a Pt-Ag / AgCl electrode is selected as the external reference electrode 8, and a saturated aqueous solution of potassium chloride containing the conductive gel of the present invention is used as the external reference solution. Preferably, the mass ratio of potassium chloride to the conductive gel is (70-80): (20-30).

[0090] The selection of this mass ratio is determined by the reaction ratio requirement of the conductive gel and potassium chloride. The conductive gel is used to conduct the measurement circuit and prevent or slow down the leakage of the electrode liquid. The conductive gel is a uniform substance and can be filled into the external reference electrode. Under special application conditions, the external reference electrode solution will use an ethanol solution of lithium chloride.

[0091] The Pt-Ag / AgCl electrode is prepared by spot welding a silver wire with a platinum wire and then covering the surface with molten silver chloride. The Pt-Ag / AgCl electrode is selected to utilize the stability of platinum to temperature changes and the expansion coefficients of platinum and glass that match when fired.

[0092] The spiral tube is in liquid contact with the sand core 6 , which is connected to the other end of the spiral tube 7 .

[0093] In a preferred embodiment of the present invention, the spiral tube liquid-connected sand core 6 is selected from at least one of a ceramic sand core, a glass sand core, a synthetic sand core and a fiber sand core.

[0094] Among them, ceramic sand cores are the most widely used, have good corrosion resistance, and have good liquid junction potential stability and reproducibility, and can be used in high temperature and high alkaline solutions.

[0095] The sand core with fiber material structure has a faster solution penetration speed and is not easy to be blocked; the porous material can be made to have a larger contact area with the solution being tested.

[0096] The liquid junction of the glass sand core is the most ideal structure. Its contact area with the solution and the seepage rate are both large, which is suitable for the determination of high viscosity, turbid liquids and low ionic strength liquids.

[0097] Therefore, the present invention preferably uses a glass sand core as a spiral tube liquid-connected sand core. When the glass sand core is a spiral tube liquid-connected sand core, the micropore diameter of the glass sand core needs to be controlled within an appropriate range. When the micropore diameter is large, the salt bridge solution in the spiral tube is easy to flow out, resulting in a waste of the salt bridge solution. However, when the micropore diameter is too small, the salt bridge solution cannot flow out smoothly. Therefore, in the present invention, the micropore diameter of the glass sand core is less than 3 μm, more preferably less than 2 μm.

[0098] like Figure 1 As shown, the potential sensing electrode of the present invention is an open liquid junction, which directly allows the conductive gel to contact the sample to be tested, which can effectively avoid the blockage of the conventional liquid junction structure and the defects of large liquid junction potential difference, so that the potential sensing electrode can still work normally in samples containing a large amount of fine suspended matter contamination.

[0099] In a second aspect, the present invention provides a method for using the electrochemical potential sensing electrode provided in the first aspect, comprising:

[0100] Step 1, washing the electrochemical potential sensing electrode with water and the solution to be tested respectively;

[0101] Preferably, the water is deionized water. More preferably, the apparatus is rinsed at least once with deionized water and at least once with the solution to be tested.

[0102] Step 2: Turn on the power supply and insert the electrochemical potential sensing electrode into the solution to be tested;

[0103] Step 3: Read the measurement results.

[0104] In order to further understand the present invention, the potential sensing electrode provided by the present invention is described below in conjunction with embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0105] Example

[0106] Example

[0107] The potential sensing electrode includes an indicator electrode, a reference electrode and a conductive gel, wherein:

[0108] The indicating electrode comprises a sensitive bulb with a front end made of blown glass, wherein the raw materials for preparing the glass are silicon dioxide, lanthanum oxide, lithium oxide and titanium oxide, and the mass ratio of silicon dioxide, lanthanum oxide, lithium oxide and titanium oxide is 14:4:1:1;

[0109] The rear end is an inner electrode shell glass tube sintered with the sensitive bulb as one body, wherein the raw materials for preparing the glass tube are silicon dioxide, boron oxide, sodium oxide and potassium oxide, and the mass ratio of silicon dioxide, boron oxide, sodium oxide and potassium oxide is 14:3:2:1;

[0110] An Ag / AgCl electrode is inserted from the opening of the inner electrode shell into the inner cavity of the sensitive bulb, wherein the sensitive bulb and the inner cavity of the inner electrode shell are filled with a saturated potassium chloride aqueous solution containing potassium dihydrogen phosphate and disodium hydrogen phosphate, wherein the mass ratio of potassium chloride, potassium dihydrogen phosphate and disodium hydrogen phosphate is 80:10:10;

[0111] The reference electrode consisted of a thin glass spiral tube with an inner diameter of 2.7 mm;

[0112] A ceramic sand core or a glass sand core embedded in the front end of the thin glass spiral tube;

[0113] A Pt-Ag / AgCl electrode is inserted into the rear end of the thin glass spiral tube. The Pt-Ag / AgCl electrode is prepared by spot welding a silver wire with a platinum wire and then covering the surface with molten silver chloride;

[0114] The spiral tube is tightly wound around the rear end of the inner electrode shell (about 10 turns), and the inner cavity of the spiral tube is filled with a saturated aqueous solution of potassium chloride containing polyacrylamide as an external reference solution, wherein the mass ratio of potassium chloride to polyacrylamide is 70:30. The outer electrode shell is connected to the junction of the sensitive bulb and the inner electrode shell and is closed;

[0115] Two symmetrical liquid connection holes with a diameter of 1.5 mm are opened at the bottom of the outer electrode shell near the sintering part of the rear end expansion part of the sensitive bulb;

[0116] The conductive gel is polyacrylamide, which fills the space between the outer electrode shell and the inner electrode shell;

[0117] The inner electrode shell, the outer electrode shell and the rear end of the spiral tube were sealed with gaskets and sealants, and the leads of the Ag / AgCl electrode and the Pt-Ag / AgCl electrode were connected to the customized S7 plug to lead out the test signal.

[0118] Experimental example

[0119] Experimental Example 1

[0120] The electrode of the embodiment was immersed in an ethanol / ether / water solution (multiphase chemical solution) with a volume ratio of 1:1:1. According to GB / T27756-2011 "Glass Electrode for pH Determination", the zero-point pH and the percentage theoretical slope PTS were recorded once every hour for 24 hours. The test data are shown in Table 1.

[0121] Table 1 Experimental data of electrode immersion in multiphase chemical solution

[0122] Time (h) Zero pH PTS Sodium difference (mV) 0 6.869 98.1％ 9.97 1 6.888 99.1％ 9.98 2 6.868 98.7％ 9.97 3 6.877 97.0％ 10.05 4 6.865 97.1％ 9.93 5 6.880 96.6％ 10.05 6 6.892 99.0％ 10.05 7 6.883 98.3％ 10.09 8 6.866 98.5％ 9.94 9 6.870 97.5％ 9.94 10 6.863 98.9％ 9.90 11 6.868 96.3％ 9.99 12 6.877 100.0％ 10.04 13 6.863 96.8％ 9.93 14 6.872 100.0％ 10.02 15 6.872 96.8％ 10.06 16 6.895 98.8％ 9.91 17 6.895 96.6％ 10.08 18 6.898 98.3％ 9.99 19 6.894 96.0％ 9.98 20 6.891 98.6％ 10.03 21 6.886 96.6％ 9.98 22 6.883 99.3％ 9.95 23 6.879 100.0％ 10.06 24 6.878 98.1％ 9.93

[0123] As can be seen from Table 1, the results of the 24 measurements are similar to the results before the electrode was immersed in the multiphase chemical solution, which shows that the electrode filled with polyacrylamide is relatively stable and will not contaminate the sample to be tested. In addition, due to the material of the sensitive bulb, the sodium difference of the electrode also changes slightly.

[0124] Experimental Example 2

[0125] The example was repeated 8 times to prepare 8 electrodes. The 8 electrodes, pH-E314 (purchased from Shanghai Shuangxu Electronics Co., Ltd.) and pH-E201-9 (purchased from Shanghai Leici Sensor Technology Co., Ltd.) were respectively immersed in an ethanol / ether / water solution (multiphase chemical solution) with a volume ratio of 1:1:1. According to GB / T27756-2011 "Glass Electrode for pH Determination", the 24-hour stability was tested. The test data are detailed in Table 2.

[0126] Table 2 Comparison of electrode stability data

[0127] Serial number The present invention (pH) pH-E314(pH) pH-E201-9(pH) 1 0.048 0.061 0.054 2 0.047 0.066 0.045 3 0.045 0.040 0.062 4 0.044 0.059 0.063 5 0.049 0.049 0.063 6 0.045 0.044 0.064 7 0.049 0.040 0.066 8 0.045 0.065 0.055 average value 0.047 0.053 0.059 RSD 4％ 21％ 12％

[0128] It can be seen that the electrode stability of the present invention is better than that of pH-E314 and pH-E201-9.

[0129] Experimental Example 3

[0130] The example was repeated three times to prepare three electrodes. The three electrodes, pH-E314 and pH-E201-9 were tested for zero-point pH, slope, response time, repeatability and sodium difference according to GB / T27756-2011 "Glass Electrode for pH Determination". The test data are shown in Table 3.

[0131] Table 3 Electrode performance comparison data

[0132]

[0133]

[0134] As can be seen from Table 3, the standard deviation of pH values ​​measured by the three electrodes is 0.013%, which is significantly lower than pH-E314 and pH-E201-9, indicating that the electrode of the present invention has better stability and the standard deviation of sodium difference is also smaller. Therefore, the comprehensive performance of the electrode of the present invention is better than that of pH-E314 and pH-E201-9.

[0135] The present invention has been described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art will appreciate that, without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention.

Claims

1. An electrochemical potential sensing electrode, characterized in that: include: an indicator electrode, a reference electrode, and a conductive gel disposed between the indicator electrode and the reference electrode; The indicator electrode comprises: Inner electrode shell; A sensitive bulb connected to one end of the inner electrode shell; an internal reference electrode inserted from the inner electrode shell and extending into the sensitive bulb; The reference electrode comprises: An outer electrode shell, one end of which is connected to the sensitive bulb; the diameter of the sensitive bulb (1) is 7-9 mm, and the film thickness is 0.04-0.06 mm; a protective sleeve is arranged outside the sensitive bulb (1); the protective sleeve is hollow and is sleeved at the connection between the reference electrode and the sensitive bulb (1), and a recess is arranged at the connection, and the recess is used for clamping to prevent separation; A liquid junction hole, which is a reference liquid junction, is provided on the outer electrode shell; A spiral tube, which is arranged around the indicator electrode; an external reference electrode, which is inserted from one end of the spiral tube; A spiral tube liquid-connected sand core is connected to the other end of the spiral tube, the spiral tube liquid-connected sand core is a glass sand core, and the micropore diameter of the glass sand core is less than 3 μm; Two liquid contact holes are symmetrically arranged below the outer electrode shell; The diameter of the liquid junction hole is 0.5~2mm; The two ends of the spiral tube are arranged in a straight line shape, and the rest of the spiral tube is arranged in a spiral shape. The number of turns of the spiral tube is 4 to 15; The inner diameter of the spiral tube is 1.5-3.5 mm, the wall thickness is 0.1-0.5 mm, and the pitch is 1-5 mm.

2. The electrochemical potential sensing electrode according to claim 1, characterized in that: The conductive gel is selected from at least one of polyacrylic acid compounds, polyacrylamide compounds, polyhydroxymethacrylate compounds, poly-N-vinyl pyrrolidone compounds and polyaniline compounds.

3. The electrochemical potential sensing electrode according to claim 1, characterized in that: The raw materials for preparing the sensitive bulb include silicon dioxide and lithium oxide; The preparation raw materials also include at least one of titanium oxide, vanadium oxide, tantalum oxide, zirconium oxide, germanium oxide and rare earth oxide. The rare earth oxide is selected from at least one of lanthanum oxide, praseodymium oxide and cerium oxide.

4. The electrochemical potential sensing electrode according to claim 1, characterized in that: The internal reference electrode is selected from a silver-silver chloride electrode, a saturated calomel electrode or a hydrogen electrode.

5. The electrochemical potential sensing electrode according to claim 1, characterized in that: The external reference electrode is a Pt-Ag / AgCl electrode.

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