A macrocyclic thiourea compound, a preparation method and application thereof in detecting nitrate ions

Abstract

The present application relates to polymer film chronopotentiometry technology, in particular to a macrocyclic thiourea compound, a preparation method and application in detecting nitrate ions.The compound is 1,3,7,9,13,15-hexaazacycloicosane-2,8,14-trithione shown in formula 1.The present application synthesizes a novel macrocyclic thiourea compound, and the compound has excellent specific recognition ability to nitrate ions.The synthesized macrocyclic thiourea compound is used as an ion carrier of a polymer sensitive film nitrate ion selective electrode, and the selectivity and sensitivity of the electrode to nitrate ions can be significantly improved.

Description

Technical Field

[0001] This invention relates to polymer membrane chronopotential analysis technology, specifically a macrocyclic thiourea compound, its preparation method, and its application in the detection of nitrate ions. Background Technology

[0002] Nitrates are widely present in environmental water bodies, soil, and food. Excessive accumulation can lead to eutrophication, food safety risks, and health hazards (such as methemoglobinemia and potential carcinogenicity). Therefore, establishing rapid, accurate, and low-cost nitrate detection methods is of great significance. Ion-selective electrode methods have become an important technology for nitrate detection due to their advantages such as simple operation, fast response speed, ease of miniaturization, and on-site detection. Among them, polymer-sensitive membrane-based ion-selective electrodes achieve specific recognition and response to nitrate ions through doping with ion carriers. Currently, the carriers used in polymer-sensitive membrane nitrate ion-selective electrodes are mainly quaternary ammonium salt ion exchangers and metal complexes. However, these carriers have limited selectivity for nitrate ions and are easily interfered with by strongly lipophilic anions such as perchlorate, thiocyanate, and iodide ions. Furthermore, these carriers have poor stability in polymer membranes and are prone to loss after long-term use or immersion, leading to decreased electrode sensitivity and shortened lifespan. In addition, the response performance of existing carriers in the detection of low-concentration nitrates still falls short of the requirements for practical sample detection. Therefore, developing novel ion carriers with higher selectivity, stronger anti-interference ability and better membrane phase stability is of great research significance and practical value for improving the performance of polymer sensitive membrane nitrate ion selective electrodes. Summary of the Invention

[0003] The purpose of this invention is to develop a macrocyclic thiourea compound, its preparation method, and its application in the detection of nitrate ions.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A macrocyclic thiourea compound, the compound being 1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione as shown in Formula 1;

[0005] Formula 1.

[0006] The method for preparing the compound, specifically the synthesis of 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione, involves reacting N-tert-butoxycarbonyl-1,3-propanediamine with carbon disulfide to obtain N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate; reacting the obtained product with 1,5-pentanediamine to obtain N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea; reducing the obtained product with trifluoroacetic acid to remove the tert-butoxycarbonyl protecting group to obtain N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea; and finally, reacting this product with N,N-diisopropylethylamine to undergo a cyclization reaction to obtain the target product.

[0007] The N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate is prepared by dissolving N-tert-butoxycarbonyl-1,3-propanediamine, triethylamine, and carbon disulfide in tetrahydrofuran, reacting at 0 °C under nitrogen protection for 0.5–1.5 hours, followed by the addition of p-toluenesulfonyl chloride, and reacting at 20–30 °C. The reaction was carried out at ℃ for 8-16 hours. After the reaction, the residue was concentrated and dissolved in ethyl acetate. The residue was washed successively with hydrochloric acid, saturated sodium bicarbonate solution, and saturated brine. The residue was then dried with anhydrous sodium sulfate to obtain a crude product. The crude product was washed with a mixture of petroleum ether / methyl tert-butyl ether, filtered, and the filter cake was thoroughly washed with petroleum ether. The collected filter cake was concentrated to obtain N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate. The amount of triethylamine added was 3-3.5 times the amount of N-tert-butoxycarbonyl-1,3-propanediamine, the amount of carbon disulfide added was 1.5-2.5 times the amount of N-tert-butoxycarbonyl-1,3-propanediamine, and the amount of p-toluenesulfonyl chloride added was 1-1.5 times the amount of N-tert-butoxycarbonyl-1,3-propanediamine.

[0008] The N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea was prepared by dissolving equal amounts of N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate and 1,5-pentanediamine in tetrahydrofuran and reacting at 25 °C under nitrogen protection for 10-14 hours. After the reaction was completed, the reaction mixture was concentrated under reduced pressure to obtain N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea.

[0009] The N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea is prepared by dissolving N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea and trifluoroacetic acid in dichloromethane and reacting at 25 °C for 4-6 hours. After the reaction is completed, the reaction mixture is concentrated under reduced pressure to obtain N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea. The amount of trifluoroacetic acid added is 14-15 times the molar amount of N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea.

[0010] The 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione is prepared by dissolving N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea, N,N-diisopropylethylamine, and carbon disulfide in ethanol and reacting at 80 °C for 14-16 hours. After the reaction is completed, the reaction mixture is successively concentrated under reduced pressure, purified by high performance liquid chromatography, and freeze-dried to obtain 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione. The amount of N,N-diisopropylethylamine added is 0.5-1.5 times the molar amount of N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea, and the amount of carbon disulfide added is 1.5-2.5 times the molar amount of N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea.

[0011] An application of the compound, specifically its use in identifying corresponding ions in a nitrate ion detection environment.

[0012] A polymer-sensitive membrane selective electrode for detecting nitrate ions, wherein the polymer-sensitive membrane in the polymer-sensitive membrane contains 1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione as an ion carrier for selectively recognizing nitrate ions, as shown in Formula 1 of claim 1.

[0013] The polymer-sensitive membrane, by weight percentage, contains 1-3 wt% 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione, 0.15-2.28 wt% tris(dodecyl)methylammonium chloride, 31.57-32.95 wt% polyvinyl chloride, and 63.15-65.9 wt% plasticizer; The plasticizer is one of 2-nitrophenyl octyl ether, bis(2-ethylhexyl) adipate, dioctyl phthalate, di(2-ethylhexyl) sebacate, or 2-fluorophenyl 2-nitrophenyl ether.

[0014] The electrode is a liquid contact electrode containing an internal filling liquid, or an all-solid-state electrode based on an ion-electron transduction layer.

[0015] The liquid contact electrode containing an internal filling fluid includes a polymer sensitive membrane, an internal filling fluid, an internal reference electrode, and an electrode cavity; wherein, the polymer sensitive membrane is adhered to the surface of the electrode cavity; the internal filling fluid is 10... -4 ~10 -2 A mol / L solution of sodium nitrate, potassium nitrate, calcium nitrate, or magnesium nitrate; the internal reference electrode is a silver / silver chloride electrode or a saturated calomel electrode.

[0016] The all-solid-state electrode based on the ion-electron transduction layer includes an electrode substrate, an ion-electron transduction layer, and a polymer sensitive film; wherein, the polymer sensitive film is located on the surface of the ion-electron transduction layer; The electrode substrate is a glassy carbon electrode, a gold electrode, a paper chip electrode, a screen-printed electrode, or a microelectrode based on a capillary glass tube; the ion-electron transduction layer is one of mesoporous carbon, fullerene, graphene, carbon nanotubes, nanoporous gold, polypyrrole, poly-3-octylthiophene and poly-3,4-ethylenedioxythiophene, molybdenum oxide, nickel-cobalt bimetallic sulfide, MXene, metal-organic framework, or covalent organic framework.

[0017] An application of the electrode, specifically its use in the detection of nitrate ions. The advantages of this invention are: 1. This invention synthesizes a novel macrocyclic thiourea compound that can form multiple hydrogen bond interactions with nitrate ions and provide a cavity that is complementary to the size and shape of nitrate ions, thereby endowing it with excellent specific recognition ability for nitrate ions.

[0018] 2. Compared with electrodes based on ion exchangers and commercially available ion carriers, the electrode using the novel macrocyclic thiourea compound of the present invention as the ion carrier has higher selectivity for nitrate ions, exhibits a linear response to nitrate ions over a wider concentration range, and combines an ideal Nernst response slope with higher sensitivity.

[0019] 3. The nitrate ion-selective electrode using the novel macrocyclic thiourea compound described in this invention as an ion carrier can directly determine the nitrate ion concentration in natural freshwater samples, exhibiting high accuracy and high reliability. Attached Figure Description

[0020] Figure 1 Synthetic route diagram of the ion support (1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione) provided in the embodiments of the present invention.

[0021] Figure 2 The 1H NMR spectrum of the ion support (1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione) provided in the embodiments of the present invention.

[0022] Figure 3 The mass spectrum of the ion support (1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione) provided in the embodiments of the present invention.

[0023] Figure 4 The real-time potential response curves of the polymer-sensitive membrane ion-selective electrode provided in this embodiment of the invention to different concentrations of nitrate ions.

[0024] Figure 5 The standard working curves obtained by testing different concentrations of nitrate ions with the polymer sensitive membrane ion-selective electrode provided in the embodiments of the present invention are shown. Detailed Implementation

[0025] The following examples further illustrate specific embodiments of the present invention. It should be noted that the specific embodiments described herein are merely for illustration and explanation and are not intended to limit the scope of the present invention.

[0026] Example 1 like Figure 1 The synthetic route shown is used to prepare 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione, and the specific steps are as follows: (1) Preparation of N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate: 15.0 g (86.1 mmol) of N-tert-butoxycarbonyl-1,3-propanediamine, 28.8 g (284 mmol) of triethylamine, and 13.1 g (172 mmol) of carbon disulfide were added to 310 mL of tetrahydrofuran and stirred at 0 °C under nitrogen for 1 hour. Then, 19.7 g (103 mmol) of p-toluenesulfonyl chloride was added to the reaction mixture, and the mixture was stirred at 25 °C for 12 hours. The reaction mixture was concentrated to obtain a residue, which was dissolved in 200 mL of ethyl acetate and washed successively with 150 mL of 0.5 mol / L hydrochloric acid, 150 mL of saturated sodium bicarbonate solution, and 100 mL of saturated brine. The residue was then dried over anhydrous sodium sulfate and filtered through a silica gel plate (100-200 mesh), and concentrated to obtain a crude product. The crude product was placed in 100 mL of a petroleum ether:methyl tert-butyl ether (5:1) mixture and washed at 25 °C for 1 hour. After filtration, the filter cake was thoroughly washed with 20.0 mL of petroleum ether, and the collected filter cake was concentrated to obtain 13.0 g (60.1 mmol) N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate.

[0027] (2) Preparation of N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea: 12.0 g (42.8 mmol) of N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate and 2.46 g (24.1 mmol) of 1,5-pentanediamine were added to 100 mL of tetrahydrofuran and stirred at 25 °C under nitrogen for 12 hours. The reaction mixture was concentrated under reduced pressure to give 11.0 g (20.6 mmol) of N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea.

[0028] (3) Preparation of N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea: 10.0 g (18.7 mmol) of N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea and 30.7 g (269 mmol) of trifluoroacetic acid were added to 100 mL of dichloromethane and stirred at 25 °C for 5 hours. The reaction mixture was then concentrated under reduced pressure to give 4.2 g (12.6 mmol) of N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea.

[0029] (4) Preparation of 1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione: 35.0 mL of ethanol containing 1.63 g (21.3 mmol) carbon disulfide was added dropwise to 143 mL of ethanol containing 3.57 g (10.7 mmol) N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea and 1.38 g (10.7 mmol) N,N-diisopropylethylamine, and stirred at 80 °C for 15 hours. The reaction mixture was concentrated under reduced pressure, and the residue was purified by high performance liquid chromatography and freeze-dried to give 487 mg (1.25 mmol) 1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione. The result was obtained by proton nuclear magnetic resonance spectroscopy (NMR). Figure 2 ) and mass spectrometry ( Figure 3 The successful synthesis of 1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione was confirmed. ¹H NMR spectrum: (400 M Hz, DMSO-) d 6) δ 8.02-6.70 (m, 6H), 3.78-3.35 (m, 12H), 1.70 (br s, 4H), 1.48 (br s, 4H), 1.37-1.16 (m, 2H). Mass spectrum: m / z= 377.3 [M+H] + . Example 2 Preparation of a liquid-contact nitrate ion-selective electrode containing an internal filling solution: The polymer-sensitive membrane components, by weight percentage: 1 wt% 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione, 0.15 wt% tris(dodecyl)methylammonium chloride, 32.95 wt% polyvinyl chloride, and 65.9 wt% 2-nitrobenzeneoctyl ether. A total of 360 mg of the above components was dissolved in 3.6 mL of tetrahydrofuran. After thorough mixing, the membrane solution was cast into a 36 mm diameter glass ring fixed to a glass plate. The sensitive membrane was obtained after the tetrahydrofuran had completely evaporated at room temperature. A sensitive membrane with a diameter of approximately 5 mm was cut from the mother membrane using a punch and then adhered to the top of the electrode cavity using tetrahydrofuran. 10 -3 A mol / L sodium nitrate solution was used as the internal filling solution, and a silver / silver chloride electrode was used as the internal reference electrode.

[0030] Example 3 Preparation of an all-solid-state nitrate ion-selective electrode based on an ion-electron transduction layer: A 3 mm diameter glassy carbon electrode was first polished with 0.05 mm alumina slurry, and then ultrasonically cleaned in deionized water and ethanol. 5 mg of ordered mesoporous carbon material was weighed and dispersed in 1 mL of tetrahydrofuran, and a homogeneous suspension was prepared by ultrasonic treatment. 6 μL of this suspension was drop-coated onto the surface of the pretreated glassy carbon electrode and dried at room temperature. The polymer-sensitive membrane component, by weight percentage, consisted of 3 wt% 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione, 2.28 wt% tris(dodecyl)methylammonium chloride, 31.57 wt% polyvinyl chloride, and 63.15 wt% di(2-ethylhexyl) sebacate. A total of 360 mg of the above membrane component was dissolved in 3.6 mL of tetrahydrofuran and stirred to form a homogeneous solution. Subsequently, 80 μL of the membrane solution was dropped onto the glassy carbon electrode modified with ordered mesoporous carbon, and after drying at room temperature, the nitrate ion selective electrode was obtained.

[0031] Example 4 Sensitivity and selectivity testing of nitrate ion selective electrodes: The nitrate ion-selective electrode prepared in Example 3 was used to form a two-electrode system with a reference electrode (a silver / silver chloride / 3 mol / L potassium chloride electrode as the reference electrode), and the potential was measured using a Chenhua 660E electrochemical workstation. The nitrate ion-selective electrode prepared in Example 3 was tested at 10... -3 In a background solution of 10 mol / L NaCl -8 ~10 -2 The potential response of nitrate ions in different concentration ranges of mol / L is as follows: Figure 4 As shown, the electrode is at 10 -5.5~10 -2 It exhibits a linear response to nitrate ions within the concentration range of mol / L, with a Nernst slope of -58.5 mV / dec and a detection limit of 2.2 × 10⁻⁶. -6 mol / L ( Figure 5 ).

[0032] Using the separate solution method, the electrode obtained in Example 3 above was tested for its reaction with ClO4. - SCN - I - ,Br - Cl - NO2 - SO4 2- HPO4 2- The selectivity was calculated, with selectivity coefficients of 1.5, 0.7, 0.1, -1.4, -3.1, -2.3, -4.3, and -4.7, respectively. A nitrate ion-selective electrode without an ion support (i.e., a membrane formulation of 0.46 wt% tris(dodecyl)methylammonium chloride, 32.85 wt% polyvinyl chloride, and 65.69 wt% 2-nitrobenzeneoctyl ether) was used for ClO4. - SCN - I - ,Br - Cl - NO2 - SO4 2- HPO4 2- The selectivity coefficients were 3.1, 2.1, 1.4, -0.5, -1.9, -0.9, -3.2, and -3.4, respectively. These results demonstrate that the polymer-sensitive membrane nitrate ion selective electrode based on a novel macrocyclic thiourea support developed in this invention exhibits good sensitivity and detection limit for nitrate ions.

[0033] Example 5 Applications of nitrate ion selective electrodes: Using the electrode obtained in Example 3 above, the concentration of nitrate ions in natural freshwater samples (lake water, river water, and snowmelt) was determined by the standard addition method, and the results were compared with those obtained by the continuous flow method. As shown in Table 1, the detection results of the ion-selective electrode are highly consistent with those of the continuous flow method, indicating that the polymer-sensitive membrane ion-selective electrode based on the novel macrocyclic thiourea carrier can serve as an effective analytical method for directly detecting the concentration of nitrate ions in natural freshwater, with good accuracy and reliability.

[0034] Table 1 Direct determination of nitrate ion concentration in natural freshwater samples (n=3)

Claims

1. A macrocyclic thiourea compound, characterized in that: The compound is 1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione, as shown in Formula 1. Formula 1.

2. The method for preparing the compound according to claim 1, characterized in that: The method for synthesizing 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione is as follows: N-tert-butoxycarbonyl-1,3-propanediamine is reacted with carbon disulfide to obtain N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate; the obtained product is reacted with 1,5-pentanediamine to obtain N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea; the obtained product is reduced with trifluoroacetic acid to remove the tert-butoxycarbonyl protecting group, yielding N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea; finally, this product undergoes a cyclization reaction with N,N-diisopropylethylamine to obtain the target product.

3. The method for preparing the compound according to claim 2, characterized in that: The N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate is prepared by dissolving N-tert-butoxycarbonyl-1,3-propanediamine, triethylamine, and carbon disulfide in tetrahydrofuran, reacting at 0 °C under nitrogen protection for 0.5–1.5 hours, followed by the addition of p-toluenesulfonyl chloride, and reacting at 20–30 °C. The reaction was carried out at ℃ for 8-16 hours. After the reaction, the residue was concentrated and dissolved in ethyl acetate. The residue was washed successively with hydrochloric acid, saturated sodium bicarbonate solution, and saturated brine. The residue was then dried with anhydrous sodium sulfate to obtain a crude product. The crude product was washed with a mixture of petroleum ether / methyl tert-butyl ether, filtered, and the filter cake was thoroughly washed with petroleum ether. The collected filter cake was concentrated to obtain N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate. The amount of triethylamine added was 3-3.5 times the amount of N-tert-butoxycarbonyl-1,3-propanediamine, the amount of carbon disulfide added was 1.5-2.5 times the amount of N-tert-butoxycarbonyl-1,3-propanediamine, and the amount of p-toluenesulfonyl chloride added was 1-1.5 times the amount of N-tert-butoxycarbonyl-1,3-propanediamine.

4. The method for preparing the compound according to claim 2 or 3, characterized in that: The N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea was prepared by dissolving equal amounts of N-tert-butoxycarbonyl-3-aminopropyl isothiocyanate and 1,5-pentanediamine in tetrahydrofuran and reacting at 25 °C under nitrogen protection for 10-14 hours. After the reaction was completed, the reaction mixture was concentrated under reduced pressure to obtain N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea.

5. The method for preparing the compound according to claim 2: the N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea is prepared by dissolving N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea and trifluoroacetic acid in dichloromethane and reacting at 25 °C for 4-6 hours; after the reaction is completed, the reaction mixture is concentrated under reduced pressure to obtain N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea; wherein, The amount of trifluoroacetic acid added is 14 to 15 times the amount of N,N'-bis[3-(tert-butoxycarbonylamino)propyl]-1,5-pentanediamine dithiourea.

6. The method for preparing the compound according to claim 2, characterized in that: The 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione is prepared by dissolving N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea, N,N-diisopropylethylamine, and carbon disulfide in ethanol and reacting at 80 °C for 14-16 hours. After the reaction is completed, the reaction mixture is successively concentrated under reduced pressure, purified by high performance liquid chromatography, and freeze-dried to obtain 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione. The amount of N,N-diisopropylethylamine added is 0.5-1.5 times the molar amount of N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea, and the amount of carbon disulfide added is 1.5-2.5 times the molar amount of N,N'-bis(3-aminopropyl)-1,5-pentanediamine dithiourea.

7. An application of the compound according to claim 1, characterized in that: The compound is used to identify the corresponding ions in a nitrate ion detection environment.

8. A polymer-sensitive membrane selective electrode for detecting nitrate ions, characterized in that: The polymer-sensitive membrane selective electrode contains 1,3,7,9,13,15-hexaazacycloeicosane-2,8,14-trithione, as shown in Formula 1 of claim 1, which serves as an ion carrier for selectively recognizing nitrate ions.

9. The polymer-sensitive membrane selective electrode for detecting nitrate ions according to claim 8, characterized in that: The polymer-sensitive membrane, by weight percentage, contains 1-3 wt% 1,3,7,9,13,15-hexaazacycloeicosano-2,8,14-trithione, 0.15-2.28 wt% tris(dodecyl)methylammonium chloride, 31.57-32.95 wt% polyvinyl chloride, and 63.15-65.9 wt% plasticizer; The plasticizer is one of 2-nitrophenyl octyl ether, bis(2-ethylhexyl) adipate, dioctyl phthalate, di(2-ethylhexyl) sebacate, or 2-fluorophenyl 2-nitrophenyl ether.

10. An application of the electrode according to claim 8, characterized in that: The electrode is used in the detection of nitrate ions.

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