A method for calibrating the standard potential of a solid-state ion-selective electrode without an instrument

Abstract

The present application relates to the technical field of all-solid-state ion selective electrode, in particular to a kind of all-solid-state ion selective electrode instrument-free standard potential calibration method, more specifically to use short-circuit electrode short-circuit all-solid-state ion selective electrode, to adjust or unify the standard electrode potential of all-solid-state ion selective electrode, maintain the original Nernst slope calibration curve of all-solid-state ion selective electrode, and the position of calibration curve can be controlled by changing the concentration of short-circuit electrode electrolyte;Wherein, the short-circuit electrode includes any one of Ag / AgCl / 3MKCl reference electrode and Ag / AgCl QRE quasi-reference electrode;The all-solid-state ion selective electrode includes electrode base, solid connection layer modified on the surface of electrode base and ion selective membrane layer modified on the surface of solid connection layer.The present application uses short-circuit electrode short-circuit all-solid-state ion selective electrode, which provides the possibility for all-solid-state ion selective electrode instrument-free standard potential calibration, greatly simplifies the calibration and unification of all-solid-state ion selective electrode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of all-solid-state ion-selective electrode, and particularly relates to a calibration method for standard electrode potential of all-solid-state ion-selective electrode without instrument. BACKGROUND

[0002] As an important electrochemical sensor, all-solid-state ion-selective electrode (SCISEs) is an important monitoring method and means in analytical chemistry, and has been widely applied in the fields of environmental monitoring, biomedical analysis, industrial analysis and marine pollution monitoring.

[0003] The repeatability of the standard electrode potential (E o ) of all-solid-state ion-selective electrode is crucial for the practical sample application of ion analysis sensor and the measurement of simpler and more accurate. At present, the standard electrode potential of all-solid-state ion-selective electrode has the problems of potential drift and non-uniformity, and the real-time calibration of solid-state ion-selective electrode is required in the ion concentration measurement process, which seriously limits the practical application of solid-state ion-selective electrode.

[0004] The measured potential of the potential sensor is the sum of the potential difference on all interfaces and interfaces of the circuit. Therefore, in order to obtain a stable standard electrode potential (E o ), the stability or controllability of the potential on all interfaces is required. Some methods show the potential to stabilize the potential of solid-state ion-selective electrode, such as using a redox couple as a solid junction layer, controlling the electrode potential of the solid junction layer by introducing the potential of the redox couple, forming, before dropping the ion-selective membrane, such as polarization of the solid junction layer based on conductive polymer, or solid junction layer based on quinone / hydroquinone modified graphite to a reasonable electrode potential, which can improve the cohesion of electrode response. However, after the electrode is prepared, the standard electrode potential E o reproducibility will also drift at an uneven rate, and there will be differences in electrode potential between different sensors.

[0005] Therefore, it is a technical problem to be solved in the field to develop a method for adjusting and unifying the standard electrode potential of solid-state ion-selective electrode without instrument, and then resetting the standard electrode potential of solid-state ion-selective electrode to a specific standard electrode potential. SUMMARY

[0006] The present application aims to provide a calibration method for standard electrode potential of all-solid-state ion-selective electrode without instrument, which short-circuits the all-solid-state ion-selective electrode by using a large-capacity Ag / AgCl / 3M KCl reference electrode or Ag / AgCl QRE quasi-reference electrode, improves the reproducibility and stability of the reset standard electrode potential, and can control the position of the calibration curve by changing the concentration of the short-circuit electrolyte, thereby solving the problem of non-uniformity of the standard electrode potential affecting the application of all-solid-state ion-selective electrode and ion detection.

[0007] The application provides a full-solid-state ion selective electrode instrument standard potential calibration method, a short-circuit electrode is used to short-circuit a full-solid-state ion selective electrode, so as to adjust or unify the standard electrode potential of the full-solid-state ion selective electrode, maintain the original Nernst slope calibration curve of the full-solid-state ion selective electrode, and control the position of the calibration curve by changing the concentration of the electrolyte of the short-circuit electrode.

[0008] The short-circuit electrode is a reference electrode with high specific capacitance and high stability, and specifically includes any one of an Ag / AgCl / 3M KCl reference electrode and an Ag / AgCl QRE quasi-reference electrode. This is because the Ag / AgCl / 3M KCl reference electrode and the Ag / AgCl QRE quasi-reference electrode have a capacitance of a higher order of magnitude than the solid connection layer of the full-solid-state ion selective electrode, and can keep the potential constant during short-circuiting. When the Ag / AgCl / 3M KCl reference electrode is used as the short-circuit electrode, the constant Cl - concentration in the short-circuit electrolyte can fix and determine the potential, thereby adjusting or unifying the standard electrode potential of the full-solid-state ion selective electrode, and maintaining the original Nernst slope calibration curve of the full-solid-state ion selective electrode. When the Ag / AgCl QRE quasi-reference electrode is used as the short-circuit electrode, the position of the calibration curve can be controlled by changing the concentration of the short-circuit electrode electrolyte.

[0009] In the calibration method, the full-solid-state ion selective electrode specifically includes an electrode substrate, a solid connection layer modified on the surface of the electrode substrate, and an ion selective membrane layer modified on the surface of the solid connection layer.

[0010] The solid connection layer includes any one of an ion-doped conductive polymer with a redox capacitance and a nanomaterial with a double-layer capacitance. The ion-doped conductive polymer includes poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), and the nanomaterial with the double-layer capacitance includes a multi-walled carbon nanotube.

[0011] When the ion-doped conductive polymer is used as the solid connection layer of the full-solid-state ion selective electrode, the full-solid-state ion selective electrode is short-circuited with the large-capacitance Ag / AgCl / 3M KCl or Ag / AgCl QRE quasi-reference electrode until the potential of the solid connection layer changes, so that the potential difference between the short-circuited full-solid-state ion selective electrode and the reference electrode approaches zero, and the specific reaction is as follows:

[0012]

[0013] The potential of the ion-doped conductive polymer-based solid contact layer is determined by its redox state and ion content, and the potential of the solid contact layer contributes to the overall measurement potential of the all-solid-state ion-selective electrode. Therefore, the standard electrode potential E of the all-solid-state ion-selective electrode can be changed by changing the oxidation / reduction system ratio of the conductive polymer solid contact layer o In addition, during the research on changing the calibration curve of the all-solid-state ion-selective electrode by the short-circuit method, the inventors also studied the possibility of using a solid contact with a double-layer capacitor instead of a redox capacitor, i.e. using a nanomaterial with a double-layer capacitor as the solid contact layer, such as a multi-walled carbon nanotube (MWCNT). The charging of the double-layer capacitor of the multi-walled carbon nanotube includes using ions opposite to the charge of the ion-selective membrane to compensate for the electric charge of the solid contact layer until the potential of the solid contact layer changes, thereby achieving the purpose of adjusting the standard electrode potential E and changing the position of the calibration curve of the all-solid-state ion-selective electrode.

[0014] The electrode substrate of the present application is not strictly limited, and specifically includes any one of a glassy carbon electrode, a carbon fiber electrode, a platinum electrode, and a gold electrode.

[0015] Preferably, the ion-doped conductive polymer is electrodeposited on the surface of the electrode substrate by a constant current polymerization method, and specifically, the electric charge of the ion-doped conductive polymer is controlled to be 1-10 mC during deposition.

[0016] Preferably, the constant current polymerization is performed using a three-electrode cell, and the thickness of the ion-doped conductive polymer solid contact layer on the electrode substrate is controlled by controlling the time of applying the current, wherein the current intensity is 0.2 mA / cm 2 , and the time is 70-700 s.

[0017] Preferably, in the three-electrode cell, the working electrode is a glassy carbon electrode, the counter electrode is a platinum wire, and the reference electrode is Ag / AgCl / 3M KCl / 0.1M NaPSS.

[0018] Preferably, the multi-walled carbon nanotubes are modified on the surface of the electrode substrate by a drop coating method; and preferably, the multi-walled carbon nanotubes are ultrasonically dispersed in an organic solvent before drop coating, wherein the mass concentration of the multi-walled carbon nanotube solution is 1.8-2.0 g / L, and the volume of the multi-walled carbon nanotube solution drop-coated on the surface of the electrode substrate is 4-16 μL.

[0019] Preferably, the ion-selective membrane layer is modified on the surface of the solid contact layer by a spin coating method to reduce the membrane resistance and improve the reproducibility of the membrane thickness, thereby obtaining a more uniform membrane resistance. Specifically, the thickness of the ion-selective membrane layer of the present application is 600 nm-1 μm.

[0020] Preferably, the electrode substrate modified with the fixed layer is placed on the support of the spin coating instrument, and the ion selective membrane reagent is drop-coated on the surface of the fixed layer at a rotation speed of 1000-2000 rpm.

[0021] Preferably, the ion selective membrane reagent is valinomycin, potassium tetrakis[3,5-bis-(trifluoromethyl)-phenyl]borate, tetra(4-chlorophenyl)borate dodecylammonium, di(2-ethylhexyl)sebacate, and a tetrahydrofuran solution of polyvinyl chloride, and the mass ratio of valinomycin, potassium tetrakis[3,5-bis-(trifluoromethyl)-phenyl]borate, tetra(4-chlorophenyl)borate dodecylammonium, di(2-ethylhexyl)sebacate, and polyvinyl chloride is specifically 1:0.5:1:65:32.5.

[0022] As the preferred solution of the present application, when the short circuit occurs, the short circuit of the all-solid-state ion selective electrode is realized by connecting the short circuit electrode with the all-solid-state ion selective electrode; and after the short circuit, the calibration is performed at the open circuit potential.

[0023] As the preferred solution of the present application, when the short circuit electrode is an Ag / AgCl QRE quasi-reference electrode, the initial potential difference to be compensated during the short circuit can be controlled by changing the concentration of the electrolyte of the short circuit electrode, thereby realizing the adjustment of the position of the calibration curve; specifically, the Ag / AgCl QRE quasi-reference electrode is placed in a chloride salt electrolyte solution, and the concentration of the chloride salt electrolyte solution is 10 -3 -10 -1 M.

[0024] As the preferred solution of the present application, when the electrode potential is measured during the calibration process, the electrode potential is first measured for at least 1 hour to ensure the stability of the electrode potential, and then the electrode potential under the corresponding current pulse is recorded to observe the influence of the current pulse on the electrode potential of the all-solid-state ion selective electrode.

[0025] As the preferred solution of the present application, before the electrode substrate is used, the nylon cloth is first polished using 0.3 μm Al2O3 polishing powder, and then cleaned and polished using 0.05 μm Al2O3 polishing powder, and finally washed with water and ethanol and ultrasonically treated for several times.

[0026] The all-solid-state ion selective electrode instrument-free standard potential calibration method of the present application has at least the following technical effects:

[0027] 1. In the method for calibrating the standard potential of the full solid-state ion selective electrode without using an instrument, the improvement of resetting the standard electrode potential can be achieved by short-circuiting the full solid-state ion selective electrode with a large-capacity solid-state Ag / AgCl / 3M KCl reference electrode or Ag / AgCl QRE quasi-reference electrode, so as to improve the reproducibility and stability of the reset standard electrode potential, adjust or unify the standard electrode potential of the full solid-state ion selective electrode, maintain the original Nernst slope calibration curve of the full solid-state ion selective electrode, and control the position of the calibration curve by changing the concentration of the electrolyte of the short-circuit electrode. Therefore, the short-circuiting of the full solid-state ion selective electrode with the short-circuit electrode makes it possible to calibrate the standard potential of the full solid-state ion selective electrode without using an instrument, and greatly simplifies the calibration and unification of the full solid-state ion selective electrode.

[0028] 2. In the method for calibrating the full solid-state ion selective electrode, when an ion-doped conductive polymer with a redox capacitance is used as the adhesion layer, the standard electrode potential is set or changed by adjusting the ratio of the oxidation / reduction part of the ion-doped conductive polymer; when a multi-walled carbon nanotube with a double-layer capacitance is used as the adhesion layer, the standard electrode potential is reset by changing the double-layer electrode potential at the interface between the multi-walled carbon nanotube and the ion-selective membrane layer. Therefore, in the calibration method of the present application, changing the size of the adhesion layer capacitance has an important influence on the stability of the potential and the adjustment of the standard electrode potential. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0030] Figure 1 The short-circuiting schematic diagram for calibrating the standard electrode potential of the full solid-state ion selective electrode without using an instrument according to the present application;

[0031] Figure 2 The relationship diagram of the potential change of the adhesion layer, the size of the adhesion layer capacitance and the applied current, wherein, Figure 2 a. The adhesion layer is PEDOT(PSS), Figure 2 b. The adhesion layer is MWCNT;

[0032] Figure 3 The reversibility schematic diagram of the potential transition of the full solid-state ion selective electrode according to the present application, wherein, Figure 3 a. The adhesion layer is PEDOT(PSS), Figure 3 b. The adhesion layer is MWCNT;

[0033] Figure 4 Ag / AgCl QRE quasi-reference electrode with high specific capacitance electrode potential stability diagram for the present application;

[0034] Figure 5 K + - calibration curve of SCISE, where, Figure 5 a is the K + - calibration curve of SCISE, Figure 5 b is the K -2 M KCl with the respective Ag / AgCl QRE quasi-reference electrode for each K + - calibration curve of SCISE after 3 days of short circuit;

[0035] Figure 6 reproducibility of the calibration curve of the Ag / AgCl QRE quasi-reference electrode for the present application and GC / MWCNT (16 μΐ) / K + - calibration curve of ISM electrode after short circuit in 10 -3 M and 10 -1 M KCl, where a is GC / MWCNT 16 μΐ / K + - calibration curve of ISM electrode after short circuit in 10 -3 M KCl with Ag / AgCl QRE (overnight), calibration of the all-solid-state ion-selective electrode in open circuit, b is 10 -1 M KCI (overnight). DETAILED DESCRIPTION

[0036] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0037] It is also important to note that the terms used herein are not intended to limit the exemplary embodiments to the specific embodiments described herein, and it is also contemplated that various embodiments can be made without departing from the spirit of the application. As used herein, unless otherwise clear from context, the singular form "a", "an", and "the" include plural references unless the context clearly indicates otherwise. Furthermore, it is to be understood that the use of a term "comprises" or "comprising" or "includes" or "including" or "has" or "having" or "contains" or "containing" or "consists" or "consisting" or "consists essentially" or "consisting essentially" in the description of a composition, a process, a method, a product, a step, a component, a device, an apparatus, a system, or the like, means that the composition, the process, the method, the product, the step, the component, the device, the apparatus, the system, or the like, contains the feature, step, operation, element, component, or the like, but is not limited thereto.

[0038] The technical solutions of the present application will be clearly and completely described below in connection with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0039] The reagents used in the following examples are as follows:

[0040] Multi-walled carbon nanotubes (MWCNT) were from DropSens (DRP-MWCNT), valinomycin, potassium tetra[3,5-bis-(trifluoromethyl)-phenyl]borate (KTFPB), tetra(4-chlorophenyl)borate dodecanyl ammonium (ETH-500), sebacic acid di(2-ethylhexyl ester) (DOS), high molecular weight polyvinyl chloride (PVC), tetrahydrofuran (THF), poly(4-styrenesulfonic acid sodium salt) (NaPSS, Mw ~ 70000), 3,4-ethylenedioxythiophene (EDOT, ≥ 97%), potassium chloride (KCl, ≥ 99.5%) and sodium chloride (NaCl, ≥ 99%) were purchased from Sigma-Aldrich.

[0041] All deionized water (ELGA Purelab Ultra, resistivity ≥ 18.2 MΩcm) used in the experiments was sourced from Sichuan Pure Water Equipment Co., Ltd., China.

[0042] Example 1

[0043] Pre-treatment of glassy carbon electrode:

[0044] Before use, the glassy carbon electrode was polished on a nylon cloth with 0.3 μm Al2O3 polishing powder, then washed and polished with 0.05 μm Al2O3 polishing powder, and finally washed with water and ethanol and ultrasonicated several times.

[0045] Preparation of the solid junction layer:

[0046] Using a 1030C electrochemical workstation (Shanghai Chenhua Instruments or Guangdong Dynechem Electronics Technology Co., Ltd.), a solid junction layer of ion-doped conductive polymer PEDOT (PSS) was prepared by applying a constant current of 0.014 mA (current density = 0.2 mA / cm2) for 714 s, 357 s and 71.4 s to deposit 10 mC, 5 mC and 1 mC of thickness, respectively, on the glassy carbon electrode, wherein a glassy carbon electrode (GCE) with a diameter of 3 mm was used as the working electrode, a platinum wire was used as the counter electrode, and Ag / AgCl / 3M KCl / 0.1M NaPSS was used as the reference electrode. 2

[0047] Preparation of the ion-selective membrane layer:​

[0048] K + The ion selective membrane reagent was a THF solution containing 1 % mass ratio (wt) of valinomycin, 0.5 % mass ratio (wt) of KTFPB, 1 % mass ratio (wt) of ETH-500, 65 % mass ratio (wt) of DOS and 32.5 % mass ratio (wt) of PVC;

[0049] The thin film K was prepared by spin coating method + - ISM, the electrode substrate modified with the immobilization layer was placed on the spin coating instrument support, K was spin coated at a speed of 1500 rpm + The ion selective membrane reagent was drop coated on the surface of the immobilization layer.

[0050] Example 2

[0051] Pre-treatment of glassy carbon electrode:

[0052] Before use, the glassy carbon electrode was polished with 0.3 pm Al2O3 polishing powder on a nylon cloth, then washed and polished with 0.05 pm Al2O3 polishing powder, and finally washed with water and ethanol and ultrasonicated for several times.

[0053] Preparation of the immobilization layer:

[0054] First, the multi-walled carbon nanotubes were ultrasonically dispersed in a THF organic solvent, and the mass concentration of the multi-walled carbon nanotube solution was controlled to be 1.9 g / L, then a volume of 4 pL and 16 pL of the multi-walled carbon nanotube solution was drop coated on the surface of the electrode substrate.

[0055] Preparation of the ion selective membrane layer:

[0056] K + The ion selective membrane reagent was a THF solution containing 1 % mass ratio (wt) of valinomycin, 0.5 % mass ratio (wt) of KTFPB, 1 % mass ratio (wt) of ETH-500, 65 % mass ratio (wt) of DOS and 32.5 % mass ratio (wt) of PVC;

[0057] The thin film K was prepared by spin coating method + - ISM, the electrode substrate modified with the immobilization layer was placed on the spin coating instrument support, K was spin coated at a speed of 1500 rpm + The ion selective membrane reagent was drop coated on the surface of the immobilization layer.

[0058] Electrode potential measurement was performed using a Lawson EMF16 multichannel potentiometer (Lawson Laboratories Inc.) and an Ag / AgCl / 3M KCl / / 1M LiAc double salt bridge reference electrode.

[0059] The electrode potential is first measured for at least 1 hour to ensure its potential stability, then a 5 min or 10 min ±1 nA current pulse is recorded, and the electrode potential is recorded again to see the effect of the current pulse on the solid-state ion-selective electrode potential; the short circuit of the electrode is realized by connecting the all-solid-state ion-selective electrode with Ag / AgCl / 3M KCl or Ag / AgCl QRE reference electrode.

[0060] As Figure 1 It is a short circuit schematic diagram for calibrating the standard electrode potential of the all-solid-state ion-selective electrode of the application, and the charging of the ion-doped conductive polymer redox capacitor or the large-area double-layer capacitor provides a basis for the stability of the electrode potential. Therefore, the all-solid-state ion-selective electrode is short-circuited by a large-capacity Ag / AgCl / 3M KCl reference electrode or an Ag / AgCl QRE quasi-reference electrode to improve the reproducibility and stability of the reset standard electrode potential, adjust or unify the standard electrode potential of the all-solid-state ion-selective electrode, and maintain the original Nernst slope calibration curve of the all-solid-state ion-selective electrode.

[0061] The application also studies different parameters that affect the open-circuit potential stability, predictability and reproducibility after short circuiting, as follows:

[0062] It is found that the capacitance of the solid connection layer has an important influence on the stability of the potential and the adjustment of the standard electrode potential. When a certain amount of electricity passes through the all-solid-state ion-selective electrode, the capacitance of the ion-doped conductive polymer PEDOT(PSS) solid connection layer will affect the size of the electrode potential shift.

[0063] Specifically, as Figure 2 a is the potential change of the 1 mC and 10 mC PEDOT(PSS) solid connection layer and the relationship between the capacitance of the solid connection layer and the applied current, i.e. the K + A +1 nA current pulse of 5 minutes or 10 minutes is applied to the ion-selective measuring electrode, and the open-circuit potential is recorded before and after the pulse sequence. When the current pulse is applied, the redox state of the ion-doped conductive polymer PEDOT(PSS) changes the most for the solid connection layer with the smallest capacitance of 1 mC. Therefore, its electrode potential changes the most compared with the thicker ion-doped conductive polymer PEDOT(PSS) solid connection layer with larger capacitance; for the solid connection layer with the largest 10 mC ion-doped conductive polymer PEDOT(PSS) capacitance, the change of its redox state and electrode potential is the smallest, and the potential change of the 1 mC PEDOT(PSS) solid-state ion-selective electrode is in a multiple relationship with the potential change of the 10 mC PEDOT(PSS) solid-state ion-selective electrode.

[0064] Similarly, the potential change of the all-solid-state ion-selective electrode with multi-walled carbon nanotubes (MWCNT) as the solid-attached layer is similar to that of the ion-doped conductive polymer PEDOT (PSS) as the solid-attached layer Figure 2 b), that is, under the same conditions, the potential of the all-solid-state ion-selective electrode with less solid-attached layer material (smaller capacitance) moves more. Thus, it is shown that the possibility of adjusting the potential of the all-solid-state ion-selective electrode is applicable to the all-solid-state ion-selective electrode with the ion-doped conductive polymer having a redox capacitance and the multi-walled carbon nanotube having a double-layer capacitance as the solid-attached layer.

[0065] When the PEDOT (PSS) or MWCNT is used as the solid-attached layer of the all-solid-state ion-selective electrode, the open circuit potential is recorded before and after the current pulse sequence by applying a 10x 5 min + 1 nA or -1 nA current pulse (with a relaxation time of 5 minutes between pulses, respectively). As shown in Figure 3 , the electrode potential of the all-solid-state ion-selective electrode with the PEDOT (PSS) (redox capacitance) and MWCNT (double-layer capacitance) solid-attached layer can move in the positive and negative directions, thus showing that the potential transition of the all-solid-state ion-selective electrode is reversible.

[0066] However, the electrode potential of the short-circuit electrode Ag / AgCl / 3M KCl reference electrode or Ag / AgCl QRE quasi-reference electrode used in the present application has high stability. When the 10x ±1 nA 5-minute or 10-minute pulse sequence is sequentially applied to the Ag / AgCl QRE quasi-reference electrode, the open circuit potential is tested for several hours, and the Figure 2 and Figure 3 corresponding current pulse experiments of the all-solid-state ion-selective electrode in

[0067] As can be seen from Figure 4 , the potential of the Ag / AgCl QRE quasi-reference electrode is completely unaffected by the applied current pulse, indicating that the Ag / AgCl QRE quasi-reference electrode has high specific capacitance electrode potential stability.

[0068] To further verify the feasibility of the method of the present application for calibrating the standard potential of the all-solid-state ion-selective electrode without an instrument, the all-solid-state ion-selective electrode is short-circuited using the Ag / AgCl QRE quasi-reference electrode.

[0069] As shown in Figure 5 a, the calibration curves of the four separate GC / MWCNT / K + ISE all-solid-state ion-selective electrodes (2x 4 μl and 2x 16 μl MWCNT) are slightly different in the position of the electrode potential, but their slopes are reproducible. In contrast, the calibration curves of theFigure 5 b in each K + -SCISE were short-circuited with their respective Ag / AgCl QRE quasi-reference electrodes in 10 -2 M KCl solution, and after 3 days of short-circuiting, K + -SCISEs' curves were then shifted to a common potential value set by the primary ion activity in the short-circuiting electrolyte. This indicates that the electrode potential of the all-solid-state ion-selective electrode is adjusted and unified after short-circuiting with the Ag / AgCl QRE quasi-reference electrode, and the original Nernst slope calibration curve of the all-solid-state ion-selective electrode can be maintained.

[0070] At the same time, the present application further verifies whether the position of the calibration curve can be controlled by changing the concentration of the short-circuiting electrolyte. As shown in Figure 6 the reproducibility of the Ag / AgCl QRE quasi-reference electrode is good, and the position of the calibration curve can be obtained with complete and accurate overlapping during short-circuiting, in which the GC / MWCNT (16 μl) / K-ISM electrode uses its respective Ag / AgCl QRE quasi-reference electrode in 10 -3 M and 10 -1 M KCl, and the potential measured in the same activity as the short-circuiting electrolyte before calibration is marked with an arrow. It can be seen that the potential difference between the all-solid-state ion-selective electrode and the reference electrode is always zero at this activity after short-circuiting, and the reproducibility of the GC / MWCNT / K + -ISM electrode is excellent, and the calibration curves are completely overlapped. Therefore, changing the concentration of the short-circuiting electrolyte can move the position of the calibration curve, but the slope of the electrode remains unchanged.

[0071] In summary, short-circuiting the all-solid-state ion-selective electrode with a short-circuiting electrode makes it possible to calibrate the all-solid-state ion-selective electrode without an instrument standard potential, and greatly simplifies the calibration and unification of the all-solid-state ion-selective electrode.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for calibrating the standard potential of an ion-selective electrode without an instrument, characterized in that, The all-solid-state ion-selective electrode is short-circuited using a short-circuit electrode to adjust or unify the standard electrode potential of the all-solid-state ion-selective electrode, maintain the original Nernst slope calibration curve of the all-solid-state ion-selective electrode, and control the position of the calibration curve by changing the concentration of the electrolyte in the short-circuit electrode. The short-circuit electrode includes either an Ag / AgCl / 3M KCl reference electrode or an Ag / AgCl QRE quasi-reference electrode. The all-solid-state ion-selective electrode includes an electrode substrate, a bonding layer modified on the surface of the electrode substrate, and an ion-selective film layer modified on the surface of the bonding layer.

2. The method of claim 1, wherein the method is a method of calibrating a full solid-state ion-selective electrode instrument standard potential without a reference electrode. The bonding layer includes any one of an ion-doped conductive polymer with redox capacitance and a nanomaterial with double-layer capacitance. The ion-doped conductive polymer includes poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid); The nanomaterials with double-layer capacitance include multi-walled carbon nanotubes.

3. The instrument-free standard potential calibration method for all-solid-state ion-selective electrodes according to claim 1, characterized in that, The electrode substrate includes any one of glassy carbon electrode, carbon fiber electrode, platinum electrode and gold electrode.

4. The instrument-free standard potential calibration method for all-solid-state ion-selective electrodes according to claim 2, characterized in that, The ion-doped conductive polymer is electrodeposited on the surface of the electrode substrate using a constant current polymerization method, and the charge of the ion-doped conductive polymer is 1-10 mC. The constant current polymerization is carried out in a three-electrode cell, and the thickness of the ion-doped conductive polymer fixed layer on the electrode substrate is controlled by controlling the time of applied current, wherein the current intensity is 0.2 mA / cm 2 , and the time is 70-700 s. In the three-electrode battery, the working electrode is a glassy carbon electrode, the counter electrode is a platinum wire, and the reference electrode is Ag / AgCl / 3MKCl / 0.1M NaPSS.

5. The instrument-free standard potential calibration method for all-solid-state ion-selective electrodes according to claim 2, characterized in that, Multi-walled carbon nanotubes were modified on the surface of the electrode substrate using a drop-coating method. Multi-walled carbon nanotubes were ultrasonically dispersed in an organic solvent and then drop-coated. The mass concentration of the multi-walled carbon nanotube solution was 1.8-2.0 g / L, and the volume of the multi-walled carbon nanotube solution drop-coated onto the electrode substrate was 4-16 μL.

6. The instrument-free standard potential calibration method for an all-solid-state ion-selective electrode according to claim 1, characterized in that, The ion-selective film layer is modified on the surface of the fixed layer by spin coating, and the thickness of the ion-selective film layer is 600 nm-1 μm; The electrode substrate modified with the bonding layer is placed on the spin coating instrument holder, and the ion-selective membrane reagent is drop-coated onto the surface of the bonding layer at a speed of 1000-2000 rpm. The mass ratio of valamicin, potassium tetrakis[3,5-bis-(trifluoromethyl)-phenyl]borate, tetradodecylammonium tetrakis(4-chlorophenyl)borate, di(2-ethylhexyl sebacate) and polyvinyl chloride in the ion-selective membrane reagent is 1:0.5:1:65:32.

5.

7. The instrument-free standard potential calibration method for all-solid-state ion-selective electrodes according to claim 1, characterized in that, During the short circuit, the all-solid-state ion-selective electrode is connected to the short-circuit electrode to achieve the short circuit of the electrode; After short-circuiting, calibration is performed at the open-circuit potential.

8. The instrument-free standard potential calibration method for all-solid-state ion-selective electrodes according to claim 1, characterized in that, When the short-circuit electrode is an Ag / AgCl QRE quasi-reference electrode, the position of the calibration curve can be controlled by changing the concentration of the electrolyte in the short-circuit electrode. The Ag / AgCl QRE quasi-reference electrode is placed in a chloride salt electrolyte solution, and the concentration of the chloride salt electrolyte solution is 10 -3 -10 -1 M.

9. The instrument-free standard potential calibration method for an all-solid-state ion-selective electrode according to claim 1, characterized in that, When measuring the electrode potential during calibration, first measure the electrode potential for at least 1 hour, and then record the electrode potential under the corresponding current pulse.

10. The instrument-free standard potential calibration method for an all-solid-state ion-selective electrode according to claim 1, characterized in that, Before use, the electrode substrate is first polished on nylon cloth with 0.3μm Al2O3 polishing powder, then cleaned and polished again with 0.05μm Al2O3 polishing powder. Finally, it is washed with water and ethanol and ultrasonicated several times.

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