A composite electrolyte, an ammonium ion detection probe prepared from the composite electrolyte, and a preparation method thereof

Abstract

The present invention provides a composite electrolyte, an ammonium ion detection probe prepared from the composite electrolyte, and a preparation method thereof, belonging to the technical field of ammonium ion detection. First, the present invention prepares a composite electrolyte by mixing (3,4-ethylenedioxythiophene), poly(4-styrenesulfonate), graphene oxide and water, and places a conductive medium into the composite electrolyte for electro-polymerization reaction to obtain a conductive medium with a composite solid electrolyte. An ammonium ion sensitive membrane solution is prepared by mixing an ionophore, a non-conductive polymer, a plasticizer, an ion exchanger and an organic solvent, and then the ammonium ion sensitive membrane solution is coated on the composite solid electrolyte. Finally, an insulating paste is coated and then dried to obtain an ammonium ion detection probe. The ammonium ion detection probe prepared by the present invention has good selectivity, low detection limit, sensitive reaction, high detection accuracy and excellent dynamic response, and is suitable for detecting low-concentration and continuously changing ammonium ion signals in aquaculture water environments.

Description

Technical Field

[0001] The present invention relates to the technical field of ammonium ion detection, and in particular to a composite electrolyte, an ammonium ion detection probe prepared from the composite electrolyte, and a preparation method thereof. Background Art

[0002] Ammonium ion is one of the important biochemical indexes in aquaculture water quality, and its content has an important impact on water quality and aquatic product quality. In aquaculture, free ammonia (ammonia molecule) and ionic ammonia (ammonium ion) are collectively referred to as ammonia nitrogen, and the ratio of these two forms of ammonia in water is related to the temperature and pH of the aquaculture water. When the content of ammonia molecules in water is low, chronic poisoning will occur in aquaculture organisms, affecting their growth and development; when the content of ammonia molecules becomes high, aquaculture organisms will enter the acute poisoning period and cannot carry out normal physiological activities, and then die in a short time. At the same time, the accumulation of ammonium ions in water will also cause toxic effects on aquaculture organisms.

[0003] At present, the main methods for detecting ammonium ions in aquaculture water on the market are spectrophotometry and test paper colorimetry. Both of these methods require pretreatment after collecting aquaculture water and cannot perform in-situ real-time detection. At the same time, the detection results are easily affected by water quality color, turbidity, etc., resulting in deviation of detection data. In addition, there are few types of ammonium ion probes sold on the market, and they all come with internal electrolytes. During continuous use, the internal filling solution will gradually leak, causing changes in electrolyte concentration and generating electrode potential offset. Moreover, high-concentration electrolytes are prone to crystal precipitation on the surface of the sensitive membrane, affecting the service life and detection accuracy of the sensitive membrane.

[0004] There are not many solid-state ammonium ion sensors in the research stage, mainly for the detection of clean water quality. The Nernst slope is generally about 55 mV / decade, while the ideal Nernst slope is 59.16 mV / decade; the detection limit is between 0.2 and 0.5 mg / L, and the highest ammonium ion concentration required in aquaculture water (0.35 mg / L, water temperature 25 °C, pH 8) is within the detection limit range, and the ammonium ion signal in aquaculture water cannot be accurately detected.

[0005] Therefore, it is of great significance to develop a probe that can sensitively and quickly detect the content of ammonium ions in aquaculture water quality. Summary of the Invention

[0006] The purpose of the present invention is to provide a composite electrolyte, an ammonium ion detection probe prepared from the composite electrolyte, and a preparation method thereof, so as to solve the technical problem that the solid-state ammonium ion sensor in the prior art cannot accurately detect the ammonium ion signal in aquaculture water.

[0007] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a composite electrolyte, which is prepared from raw materials comprising the following parts by mass:

[0009]

[0010] The present invention provides an ammonium ion detection probe prepared from the composite electrolyte. The ammonium ion detection probe comprises a composite solid electrolyte, a conductive medium, an ammonium ion sensitive membrane, and an insulating coating. The composite solid electrolyte is prepared from the composite electrolyte.

[0011] Furthermore, the conductive medium includes a gold conductive medium, a silver conductive medium, or a copper conductive medium.

[0012] Furthermore, the ammonium ion sensitive membrane is prepared from raw materials comprising the following parts by mass:

[0013]

[0014] Furthermore, the ion carrier comprises ammonium ion carrier I and / or 18-crown-6; the non-conductive polymer comprises polyvinyl chloride and / or polyurethane; the plasticizer comprises one or more of 2-nitrophenyl octyl ether, bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) sebacate, and phthalate; the ion exchanger comprises one or more of sodium tetraphenylborate, potassium tetrakis(4-chlorophenyl)borate, and potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

[0015] Furthermore, the insulating coating is prepared from an insulating slurry.

[0016] The present invention provides a method for preparing an ammonium ion detection probe, comprising the following steps:

[0017] (1) Placing the conductive medium into the composite electrolyte and performing an electro-polymerization reaction under a protective atmosphere to obtain a conductive medium with a composite solid electrolyte;

[0018] (2) Dissolving the non-conductive polymer, plasticizer, ion exchanger, and ion carrier in an organic solvent to obtain an ammonium ion sensitive membrane solution;

[0019] (3) Coating the ammonium ion sensitive membrane solution on the composite solid electrolyte, and then coating the insulating slurry on the conductive medium, and performing a drying treatment to obtain the ammonium ion detection probe.

[0020] Furthermore, in the step (1), the method adopted for the electro-polymerization reaction includes chronopotentiometry or cyclic voltammetry.

[0021] Further, in the step (2), the organic solvent includes tetrahydrofuran or cyclohexanone, and the solid-liquid ratio of the non-conductive polymer to the organic solvent is 1 mg: 10-20 μL.

[0022] Further, in the step (3), the coating amount of the ammonium ion-sensitive membrane solution is 1-1.5 μL / mm.

[0023] Advantages of the present invention:

[0024] (1) The present invention uses the composite solid electrolyte of poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) / reduced graphene oxide to replace the internal charging electrolyte in the traditional ion-selective probe. Poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) can ensure the conversion between ions and electrons, and the doping of reduced graphene oxide enhances the electron transfer ability, making the entire composite solid electrolyte more sensitive and rapid in response to ion concentration changes. As a result, the entire probe has better Nernst response characteristics, lower detection limit and better stability, and eliminates the maintenance step of replacing the internal charging electrolyte. At the same time, the electro-polymerization method is not limited by the shape and structure of the probe, providing feasibility for the subsequent research and development of probes with different shapes.

[0025] (2) The present invention uses a non-conductive polymer and a plasticizer as the skeleton of the ammonium ion-sensitive membrane, which is an important carrier of the ammonium ion-sensitive membrane. The ion exchanger can make the ion flow inside the ammonium ion-sensitive membrane smoother, smoothly realizing the conversion from chemical signal to electrical signal. The ionophore is the key material of the ammonium ion-sensitive membrane, and the formula of the entire ammonium ion-sensitive membrane determines the sensitivity, accuracy and anti-interference ability of the ammonium ion detection probe.

[0026] (3) The ammonium ion detection probe prepared by the present invention realizes the full solidification of the ammonium ion detection probe for aquaculture water, has stronger adaptability to the detection environment, realizes the maintenance-free of the ammonium ion detection probe, and has a longer service life.

[0027] (4) The ammonium ion detection probe of the present invention has good selectivity, low detection limit, sensitive reaction, high detection accuracy and excellent dynamic response, and is suitable for detecting low-concentration and continuously changing ammonium ion signals in aquaculture water environment. Description of the Drawings

[0028] Figure 1 It is an enlarged view of the overall structure of the ammonium ion detection probe, mainly including: ammonium ion-sensitive membrane, composite solid electrolyte, conductive medium, insulating coating;

[0029] Figure 2 It is the calibration curve graph of the ammonium ion detection probe prepared in Example 1 for testing the standard buffer solution;

[0030] Figure 3 Calibration curve graph of the ammonium ion detection probe prepared in Comparative Example 1 for testing the standard buffer solution;

[0031] Figure 4 Calibration curve graph of the ammonium ion detection probe prepared in Comparative Example 2 for testing the standard buffer solution;

[0032] Figure 5 Two - electrode water sample detection system diagram composed of the ammonium ion detection probe and the reference electrode. Specific implementation mode

[0033] The present invention provides a composite electrolyte, which is prepared from raw materials comprising the following mass parts:

[0034]

[0035] In the present invention, the mass part of (3,4 - ethylenedioxythiophene) is preferably 0.22 - 0.28 parts, and more preferably 0.24 - 0.26 parts.

[0036] In the present invention, the mass part of poly (sodium 4 - styrenesulfonate) is preferably 0.45 - 0.65 parts, and more preferably 0.5 - 0.6 parts.

[0037] In the present invention, the mass part of graphene oxide is preferably 0.15 - 0.25 parts, and more preferably 0.2 parts.

[0038] In the present invention, the mass part of water is preferably 190 - 210 parts, and more preferably 200 parts.

[0039] The present invention provides an ammonium ion detection probe prepared from the composite electrolyte. The ammonium ion detection probe comprises a composite solid electrolyte, a conductive medium, an ammonium ion - sensitive membrane and an insulating coating, and the composite solid electrolyte is prepared from the composite electrolyte.

[0040] In the present invention, the conductive medium includes a gold conductive medium, a silver conductive medium or a copper conductive medium, preferably a gold conductive medium or a silver conductive medium, and more preferably a gold conductive medium.

[0041] In the present invention, the ammonium ion - sensitive membrane is prepared from raw materials comprising the following mass parts:

[0042]

[0043] In the present invention, the mass part of the ionophore is preferably 2.5 parts; the ionophore comprises ammonium ionophore I and / or 18 - crown - 6, preferably ammonium ionophore I.

[0044] In the present invention, the mass fraction of the non-conductive polymer is preferably 32 to 34 parts, more preferably 33 parts; the non-conductive polymer includes polyvinyl chloride and / or polyurethane, preferably polyvinyl chloride.

[0045] In the present invention, the mass fraction of the plasticizer is preferably 63.5 to 64.5 parts, more preferably 64 parts; the plasticizer includes one or more of 2-nitrophenyl octyl ether, bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) sebacate, and phthalate, preferably one or more of 2-nitrophenyl octyl ether, bis(2-ethylhexyl) adipate, and bis(2-ethylhexyl) sebacate, and further preferably 2-nitrophenyl octyl ether and / or bis(2-ethylhexyl) adipate.

[0046] In the present invention, the mass fraction of the ion exchanger is preferably 0.45 parts; the ion exchanger includes one or more of sodium tetraphenylborate, potassium tetrakis(4-chlorophenyl)borate, and potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, preferably sodium tetraphenylborate and / or potassium tetrakis(4-chlorophenyl)borate, and further preferably sodium tetraphenylborate.

[0047] In the present invention, the insulating coating is prepared from an insulating slurry.

[0048] The insulating slurry used in the present invention is purchased from Baohua Industry China Co., Ltd., with the model SS-8395 and light blue color.

[0049] The present invention provides a method for preparing an ammonium ion detection probe, comprising the following steps:

[0050] (1) Put the conductive medium into the composite electrolyte and carry out an electro-polymerization reaction under a protective atmosphere to obtain a conductive medium with a composite solid electrolyte;

[0051] (2) Dissolve the non-conductive polymer, plasticizer, ion exchanger, and ionophore in an organic solvent to obtain an ammonium ion-sensitive membrane solution;

[0052] (3) Coat the ammonium ion-sensitive membrane solution on the composite solid electrolyte, and then coat the insulating slurry on the conductive medium, and after drying treatment, an ammonium ion detection probe is prepared.

[0053] Before preparing the ammonium ion detection probe, the conductive medium is pretreated, and the specific steps are as follows: (1) Cut the conductive medium into pieces with a length of 6-10 cm, and prepare suspension solutions with alumina particle sizes of 1.5 μm, 0.5 μm, and 0.05 μm respectively, where the alumina content is 60-100 mg / mL; (2) Then, drop the suspension solution with an alumina particle size of 1.5 μm onto the suede, wrap the conductive medium with the suede, and while rotating the conductive medium, slowly pull the conductive medium outwards. After repeating this step for 2-3 minutes, wash the conductive medium with deionized water; (3) Repeat step (2) with the suspension solution with an alumina particle size of 0.5 μm; (4) Repeat step (2) with the suspension solution with an alumina particle size of 0.05 μm; (5) Place the conductive medium in a 50 vol% ethanol solution and ultrasonically clean it for 6-12 minutes, then place it in a 0.8 mol / L dilute sulfuric acid solution and ultrasonically clean it for 5-10 minutes. Finally, place it in deionized water and ultrasonically clean it for 6-12 minutes. After drying the conductive medium with nitrogen, vertically insert it into the foam board with the cleaned end facing upwards, and store it in a drying oven at 80 °C for standby.

[0054] In the present invention, the length of the conductive medium is preferably 7-9 cm, and more preferably 8 cm.

[0055] In the present invention, in the step (1), the methods adopted for the electropolymerization reaction include chronopotentiometry or cyclic voltammetry, and cyclic voltammetry is preferred.

[0056] The present invention adopts a three-electrode system, using the pretreated conductive medium as the working electrode, a platinum electrode as the counter electrode, and a silver / silver chloride electrode as the reference electrode. In the prepared composite electrolyte solution, poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) / reduced graphene oxide solid electrolyte is prepared by cyclic voltammetry. The low potential of the scanning potential is -0.4 to -0.2 V, and the high potential is 0.8 to 1.0 V. Scanning from the low potential to the high potential triggers the electropolymerization reaction. The scanning rate is 30-100 mV / s, and 10-20 cycles are scanned.

[0057] In the present invention, in the step (2), the organic solvent includes tetrahydrofuran or cyclohexanone, and tetrahydrofuran is preferred.

[0058] In the present invention, the solid-liquid ratio of the non-conductive polymer to the organic solvent is 1 mg: 10-20 μL, preferably 1 mg: 12-18 μL, and more preferably 1 mg: 15 μL.

[0059] In the present invention, in the step (3), the coating amount of the ammonium ion-sensitive membrane solution is 1-1.5 μL / mm, preferably 1.1-1.4 μL / mm, and more preferably 1.2-1.3 μL / mm.

[0060] In the present invention, the insulating paste is coated on the middle part of the conductive medium, and the coating amount is 1 to 1.5 μL / mm.

[0061] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0062] Embodiment 1

[0063] 28 mg of (3,4-ethylenedioxythiophene), 55 mg of poly(sodium 4-styrenesulfonate), 20 mg of graphene oxide and 20 g of deionized water are mixed to prepare a composite electrolyte. Then, the composite electrolyte is stirred for 12 h. After introducing nitrogen for 10 min, an 8-cm gold conductive medium is placed in the composite electrolyte. Using the gold conductive medium as the working electrode, a platinum electrode as the counter electrode, and a silver / silver chloride electrode as the reference electrode, poly(3,4-ethylenedioxythiophene) / poly(sodium 4-styrenesulfonate) / reduced graphene oxide solid electrolyte is prepared by cyclic voltammetry. The scanning potential is controlled to scan from -0.4 V to 1.0 V to initiate the electropolymerization reaction. The scanning rate is 50 mV / s, and the number of scanning cycles is 15. Finally, the gold conductive medium with the composite solid electrolyte is taken out and placed in a drying oven at 80 °C for drying for 12 h.

[0064] 2 mg of ammonium ion carrier I, 63.3 mg of 2-nitrophenyl octyl ether, 0.4 mg of sodium tetraphenylborate and 31.7 mg of polyvinyl chloride are added to 475.5 μL of tetrahydrofuran. Then, the mixture is continuously shaken until the suspension becomes a transparent, clear and uniform viscous solution. The obtained ammonium ion-sensitive membrane solution is placed in a refrigerator at 4 °C for 2 h.

[0065] The above-obtained ammonium ion-sensitive membrane solution is drop-coated onto the composite solid electrolyte, and the coating amount is 1.5 μL / mm, and the coating length is 8 mm. Finally, the insulating paste is coated on the gold conductive medium, and the coating amount is 1.2 μL / mm, and then placed in a drying oven at 80 °C for drying for 24 h to prepare an ammonium ion detection probe.

[0066] Embodiment 2

[0067] 30 mg of (3,4-ethylenedioxythiophene), 40 mg of poly(sodium 4-styrenesulfonate), 10 mg of graphene oxide and 18 g of deionized water were mixed to prepare a composite electrolyte. Then the composite electrolyte was stirred for 12 h. After purging nitrogen for 10 min, an 8-cm copper conductive medium was placed into the composite electrolyte. Using the copper conductive medium as the working electrode, a platinum electrode as the counter electrode, and a silver / silver chloride electrode as the reference electrode, poly(3,4-ethylenedioxythiophene) / poly(sodium 4-styrenesulfonate) / reduced graphene oxide solid electrolyte was prepared by cyclic voltammetry. The scanning potential was controlled to scan from -0.2 V to 0.8 V to initiate the electropolymerization reaction. The scanning rate was 100 mV / s and the number of scanning cycles was 20. Finally, the gold conductive medium with the composite solid electrolyte was taken out and placed in an oven at 80 °C for drying for 12 h.

[0068] 3 mg of 18-crown-6, 64 mg of bis(2-ethylhexyl) sebacate, 0.45 mg of potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate and 34.3 mg of polyurethane were added to 343 μL of tetrahydrofuran. Then the mixture was continuously shaken until the suspension became a transparent, clear and homogeneous viscous solution. The obtained ammonium ion-sensitive membrane solution was placed in a refrigerator at 4 °C for 2 h.

[0069] The above-obtained ammonium ion-sensitive membrane solution was drop-coated onto the composite solid electrolyte with a drop-coating amount of 1 μL / mm and a coating length of 5 mm. Finally, the insulating paste was coated onto the copper conductive medium with a coating amount of 1.0 μL / mm and placed in an oven at 80 °C for drying for 24 h to prepare an ammonium ion detection probe.

[0070] Example 3

[0071] 20 mg of (3,4-ethylenedioxythiophene), 70 mg of poly(sodium 4-styrenesulfonate), 30 mg of graphene oxide and 22 g of deionized water were mixed to prepare a composite electrolyte. Then the composite electrolyte was stirred for 12 h. After purging nitrogen for 10 min, an 8-cm silver conductive medium was placed into the composite electrolyte. Using the silver conductive medium as the working electrode, a platinum electrode as the counter electrode, and a silver / silver chloride electrode as the reference electrode, poly(3,4-ethylenedioxythiophene) / poly(sodium 4-styrenesulfonate) / reduced graphene oxide solid electrolyte was prepared by cyclic voltammetry. The scanning potential was controlled to scan from -0.3 V to 0.9 V to initiate the electropolymerization reaction. The scanning rate was 30 mV / s and the number of scanning cycles was 10. Finally, the gold conductive medium with the composite solid electrolyte was taken out and placed in an oven at 80 °C for drying for 12 h.

[0072] 2.5 mg of ammonium ionophore I, 64.8 mg of bis(2-ethylhexyl) adipate, 0.5 mg of potassium tetrakis(4-chlorophenyl)borate, and 33 mg of polyvinyl chloride were added to 660 μL of tetrahydrofuran. Then, the mixture was continuously shaken until the suspension became a clear, homogeneous, viscous solution. The obtained ammonium ion-sensitive membrane solution was placed in a refrigerator at 4 °C for 2 h.

[0073] The above-obtained ammonium ion-sensitive membrane solution was drop-coated onto the composite solid electrolyte at a drop-coating amount of 1.2 μL / mm and a coating length of 7 mm. Finally, the insulating paste was coated onto the silver conductive medium at a coating amount of 1.3 μL / mm and placed in an oven at 80 °C for drying for 24 h to prepare an ammonium ion detection probe.

[0074] Comparative Example 1

[0075] 28 mg of (3,4-ethylenedioxythiophene), 55 mg of poly(4-styrenesulfonate), 20 mg of graphene oxide, and 20 g of deionized water were mixed to prepare a composite electrolyte. Then, the composite electrolyte was stirred for 12 h. After purging with nitrogen for 10 min, an 8-cm gold conductive medium was placed in the composite electrolyte. Using the gold conductive medium as the working electrode, a platinum electrode as the counter electrode, and a silver / silver chloride electrode as the reference electrode, poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) / reduced graphene oxide solid electrolyte was prepared by cyclic voltammetry. The scanning potential was controlled to scan from -0.4 V to 1.0 V to initiate the electropolymerization reaction. The scanning rate was 50 mV / s, and the number of scanning cycles was 15. Finally, the gold conductive medium with the composite solid electrolyte was taken out and placed in an oven at 80 °C for drying for 12 h.

[0076] 1 mg of ammonium ionophore I, 70 mg of 2-nitrophenyloctyl ether, 1 mg of sodium tetraphenylborate, and 25 mg of polyvinyl chloride were added to 475.5 μL of tetrahydrofuran. Then, the mixture was continuously shaken until the suspension became a clear, homogeneous, viscous solution. The obtained ammonium ion-sensitive membrane solution was placed in a refrigerator at 4 °C for 2 h.

[0077] The above-obtained ammonium ion-sensitive membrane solution was drop-coated onto the composite solid electrolyte at a drop-coating amount of 1.5 μL / mm and a coating length of 8 mm. Finally, the insulating paste was coated onto the gold conductive medium at a coating amount of 1.2 μL / mm and placed in an oven at 80 °C for drying for 24 h to prepare an ammonium ion detection probe.

[0078] Comparative Example 2

[0079] 10 mg of (3,4-ethylenedioxythiophene), 75 mg of poly(sodium 4-styrenesulfonate), 40 mg of graphene oxide and 20 g of deionized water were mixed to prepare a composite electrolyte. Then the composite electrolyte was stirred for 12 h. After purging nitrogen for 10 min, an 8-cm gold conductive medium was placed into the composite electrolyte. Using the gold conductive medium as the working electrode, a platinum electrode as the counter electrode, and a silver / silver chloride electrode as the reference electrode, poly(3,4-ethylenedioxythiophene) / poly(sodium 4-styrenesulfonate) / reduced graphene oxide solid electrolyte was prepared by cyclic voltammetry. The scanning potential was controlled to scan from -0.4 V to 1.0 V to initiate the electropolymerization reaction. The scanning rate was 50 mV / s and the number of scanning cycles was 15. Finally, the gold conductive medium with the composite solid electrolyte was taken out and placed in an 80 °C drying oven for 12 h.

[0080] 2 mg of ammonium ion carrier I, 63.3 mg of 2-nitrophenyl octyl ether, 0.4 mg of sodium tetraphenylborate and 31.7 mg of polyvinyl chloride were added to 475.5 μL of tetrahydrofuran. Then the mixture was continuously shaken until the suspension became a transparent, clear and homogeneous viscous solution. The obtained ammonium ion-sensitive membrane solution was placed in a 4 °C refrigerator for 2 h.

[0081] The above-obtained ammonium ion-sensitive membrane solution was drop-coated onto the composite solid electrolyte with a drop-coating amount of 1.5 μL / mm and a coating length of 8 mm. Finally, the insulating paste was coated onto the gold conductive medium with a coating amount of 1.2 μL / mm and placed in an 80 °C drying oven for 24 h to prepare an ammonium ion detection probe.

[0082] Performance test:

[0083] (1) Standard buffer solution test

[0084] The ammonium ion detection probes prepared in Example 1, Comparative Example 1 and Comparative Example 2 were used to detect 11 ammonium chloride buffer solutions with a pH of 8, a water temperature of 25 °C and a concentration ranging from 10 -7 M to 10 -2 M. The detection order was to detect the ammonium chloride buffer solutions in ascending order of concentration, and the detection was repeated three times. The calibration curves of the detection results are as shown in Figure 2 、 Figure 3 、 Figure 4 . It can be obtained from the Figure 2 calibration curve that the linear range of the electrode is 10 -7 M to 10 -2For M, the slope of the obtained fitting curve is 59.46 ± 0.64 mV / decade, and the lower detection limit of the electrode is 0.81 ± 0.27 μM. The slope of the ammonium ion detection probe prepared in Example 1 is close to and slightly greater than the ideal Nernst slope (59.16 mV / decade), and the lower detection limit reaches 0.015 mg / L, which is much lower than the maximum ammonium ion concentration required in aquaculture water (0.35 mg / L, water temperature 25 °C, pH 8). This result proves that the ammonium ion detection probe prepared in Example 1 has high detection sensitivity and is sensitive to low-concentration ammonium ions.

[0085] The difference between Comparative Example 1 and Example 1 lies in the different ratios of the components in the ammonium ion-sensitive membrane of the ammonium ion detection probe. Comparing Figure 2 and Figure 3 's calibration curves, the slope of the calibration curve obtained in Comparative Example 1 decreased to 24.35 mV / decade, and the lower detection limit was 2.10 μM (the lower detection limit of Example 1 was 0.81 μM), which was significantly higher than the lower detection limit of the ammonium ion detection probe prepared in Example 1.

[0086] The difference between Comparative Example 2 and Example 1 lies in the different ratios of the components in the composite solid electrolyte of the ammonium ion detection probe. Comparing Figure 2 and Figure 4 's calibration curves, the slope of the calibration curve obtained in Comparative Example 2 decreased to 10.91 mV / decade, and the lower detection limit became 7.80 μM (the lower detection limit of Example 1 was 0.81 μM), which was significantly higher than the lower detection limit of the ammonium ion detection probe prepared in Example 1.

[0087] (2) Actual water sample detection

[0088] During water sample detection, the ammonium ion detection probe is used as the detection head to form a two-electrode system with a commercial Ag / AgCl reference electrode, and is connected to the electrode with a shielded wire to ensure signal output while reducing external interference, and is connected to the detection instrument with a standard connector (as Figure 5 shown).

[0089] Tap water and pond aquaculture water were taken for testing respectively. The same amount of 0.01 mol / L ammonium chloride buffer solution was added to these two water samples, and the ammonium ion content in the water samples was measured with the ammonium ion detection probe prepared in Example 1. The results are shown in Table 1. It can be seen that the relative deviation between the actual measurement value and the theoretical value is less than 0.5%, indicating that the ammonium ion detection probe developed in the present invention can be used in aquaculture water environments with complex components.

[0090] Table 1 Detection results of actual water samples

[0091]

[0092] As can be seen from the above embodiments, the present invention provides a composite electrolyte, an ammonium ion detection probe prepared from the composite electrolyte, and a preparation method thereof. First, (3,4-ethylenedioxythiophene), poly(sodium 4-styrenesulfonate), graphene oxide, and water are formulated into a composite electrolyte, and a conductive medium is placed in the composite electrolyte for electro-polymerization reaction to obtain a conductive medium with a composite solid electrolyte. An ammonium ion sensitive membrane solution is prepared by mixing an ionophore, a non-conductive polymer, a plasticizer, an ion exchanger, and an organic solvent, and then the ammonium ion sensitive membrane solution is coated on the composite solid electrolyte. Finally, an insulating paste is coated and dried to obtain an ammonium ion detection probe. The ammonium ion detection probe prepared by the present invention realizes the all-solidification of the ammonium ion detection probe for aquaculture water, has good selectivity, a low detection limit, sensitive reaction, high detection accuracy, excellent dynamic response, and is suitable for detecting low-concentration and continuously changing ammonium ion signals in the aquaculture water environment.

[0093] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An ammonium ion detection probe, characterized in that, The ammonium ion detection probe comprises a composite solid electrolyte, a conductive medium, an ammonium ion sensitive film and an insulating coating, and the composite solid electrolyte is prepared from a composite electrolyte solution; The composite electrolyte solution is prepared from raw materials comprising the following parts by mass: 3,4-Ethylenedioxythiophene 0.2 - 0.3 part Poly(sodium 4-styrenesulfonate) 0.4 - 0.7 part Graphene oxide 0.1 - 0.3 part Water 180 - 220 parts; The conductive medium includes a gold conductive medium, a silver conductive medium or a copper conductive medium; The composite solid electrolyte is composed of poly(3,4-ethylenedioxythiophene), poly(sodium 4-styrenesulfonate) and reduced graphene oxide; The ammonium ion sensitive film is prepared from raw materials comprising the following parts by mass: Ionophore 2 - 3 parts Non-conductive polymer 31.7 - 34.3 parts Plasticizer 63.3 - 64.8 parts Ion exchanger 0.4 - 0.5 part; The ionophore includes ammonium ionophore I and / or 18-crown-6; the non-conductive polymer includes polyvinyl chloride and / or polyurethane; the plasticizer includes one or more of 2-nitrophenyl octyl ether, bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) sebacate and phthalate; the ion exchanger includes one or more of sodium tetraphenylborate, potassium tetrakis(4-chlorophenyl)borate and potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

2. The ammonium ion detection probe according to claim 1, characterized in that, The insulating coating is prepared from an insulating slurry.

3. A method for preparing the ammonium ion detection probe according to claim 1 or 2, characterized in that, It includes the following steps: (1) Put the conductive medium into the composite electrolyte solution, and carry out an electropolymerization reaction under a protective atmosphere to obtain a conductive medium with a composite solid electrolyte; (2) Dissolve the non-conductive polymer, plasticizer, ion exchanger and ionophore in an organic solvent to obtain an ammonium ion sensitive film solution; (3) Coat the ammonium ion sensitive film solution on the composite solid electrolyte, and then coat the insulating slurry on the conductive medium, and after drying treatment, an ammonium ion detection probe is prepared.

4. The preparation method of the ammonium ion detection probe according to claim 3, wherein, In the step (1), the method adopted for the electropolymerization reaction includes chronopotentiometry or cyclic voltammetry.

5. The preparation method of the ammonium ion detection probe according to claim 4, characterized in that, In the step (2), the organic solvent includes tetrahydrofuran or cyclohexanone, and the solid-liquid ratio of the non-conductive polymer to the organic solvent is 1 mg: 10 - 20 μL.

6. The preparation method of the ammonium ion detection probe according to claim 4 or 5, characterized in that, In the step (3), the coating amount of the ammonium ion sensitive film solution is 1 - 1.5 μL / mm.

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