Preparation of Ti-doped sheet-like ferrierite molecular sieve and its application in electrochemical sensor for detection of rutin

Abstract

The application discloses a titanium-doped sheet-layer FER molecular sieve and application of the titanium-doped sheet-layer FER molecular sieve in an electrochemical sensing detector for rutin, and belongs to the technical field of molecular sieve synthesis and electrochemical sensor detection. n -O-(p-C6H4)2-O-(CH2) n -NH-C2H4-NH2; wherein n is 10-16. The titanium-doped sheet-layer FER molecular sieve is immobilized with chitosan to obtain a composite material, an electrode is modified by using the obtained composite material to construct an electrochemical sensor, and the obtained electrochemical sensor is used for detecting and analyzing rutin. The concentration linear range of the electrochemical sensor for detecting rutin reaches 0.1-10 micromoles per liter, the concentration detection range is wide, the detection sensitivity, accuracy, repeatability and selectivity are high, the detection lower limit is low, and the stability is good.

Description

Technical Field

[0001] This invention relates to the fields of molecular sieve synthesis technology and electrochemical sensor detection technology. Specifically, it relates to the preparation of a Ti-doped sheet-like FER molecular sieve and its application in a rutin electrochemical sensor detector. Background Technology

[0002] Rutin, also known as vitamin P, is a common polyphenolic flavonoid. The human body cannot synthesize rutin and must obtain it from food. It is mainly found in apricots, dates, cherries, orange peel, and citrus fruits, with particularly high concentrations in locust flower buds and buckwheat flowers. Due to its significant biological and pharmacological activities, it is widely used in the healthcare system. In daily life, rutin is commonly used as an antioxidant and nutritional enhancer. It also exhibits good inhibitory effects on some human diseases, demonstrating anti-tumor, antihypertensive, antibacterial, antiviral, and anti-edema properties. In particular, it effectively regulates capillary osmotic pressure and stabilizes platelets. However, excessive rutin intake can lead to central nervous system depression, gastrointestinal bleeding, and kidney damage. Therefore, quantitative analysis of rutin in food and pharmaceuticals is of great significance in both food and drug control.

[0003] Currently, methods for detecting rutin include spectroscopic, chromatographic, and electrochemical methods. Some commonly used analytical methods, such as high-performance liquid chromatography (HPLC), capillary electrophoresis, and spectrophotometry, have been applied to the determination of rutin. However, some of these methods are time-consuming, costly, or require complex pretreatment processes, hindering their further application. Electrochemical analysis is a class of instrumental analytical methods based on the electrochemical properties of substances in solution. It relies on the electrochemical properties and their changing patterns of substances in solution, establishing qualitative and quantitative analysis of components based on the relationship between electrical quantities such as potential, conductivity, current, and charge and certain quantities of the analyte. Compared with these methods, electrochemical determination has advantages such as high reliability, fast reaction, inexpensive instruments, low energy consumption, simple operation, time saving, high sensitivity, and strong selectivity. In particular, its equipment is portable and can be used for on-site determination. In recent years, with the development of nanoscience and nanotechnology, many nanomaterial electrodes that can significantly improve the signal intensity of electrochemical sensors and achieve ultrasensitive determination have been applied to the electrochemical determination of rutin.

[0004] Arvand et al. (Arvand. A new electrochemical sensing platform based on binary composite of graphene oxide-chitosan for sensitive rutin determination. Food Analytical Methods 10(2017):2332-2345.) disclosed a novel electrochemical sensor based on a graphene oxide-chitosan binary composite for the sensitive determination of rutin, achieving a linear concentration range of 0.9–90 μmol / L and a detection limit of 0.56 μmol / L. However, the existing electrochemical sensor has a relatively high detection limit for rutin, which may not cover the detection needs under certain special conditions (such as low rutin levels), and its detection sensitivity needs further improvement. Summary of the Invention

[0005] To address the issue that existing electrochemical sensors still have a narrow concentration linearity range for rutin detection, which may not be able to cover the detection needs in certain special cases (such as low rutin states), and that their detection sensitivity needs to be further improved, the primary objective of this invention is to provide a carbon-chain organic compound.

[0006] Another object of the present invention is to provide the application of the said organic compound in the preparation of FER molecular sieves.

[0007] Another object of the present invention is to provide a titanium-doped sheet-like FER molecular sieve.

[0008] Another object of the present invention is to provide a titanium-doped sheet-like FER molecular sieve-supported chitosan composite material.

[0009] Another object of the present invention is to provide an electrochemical sensor.

[0010] Another object of the present invention is to provide a three-electrode system.

[0011] Another object of the present invention is to provide the application of the titanium-doped sheet FER molecular sieve or the titanium-doped sheet FER molecular sieve-supported chitosan composite material or the electrochemical sensor or the three-electrode system in the detection of rutin.

[0012] The objective of this invention is achieved through the following technical methods:

[0013] A carbon-chain organic compound, the structural formula of which is: NH2-C2H4-NH-(CH2) n -O-(p-C6H4)2-O-(CH2) n-NH-C2H4-NH2; where n is 10 to 16.

[0014] The carbon-chain organic compound designed in this invention serves as a template agent, playing a role in structure guidance and pore filling in the preparation of FER molecular sieves. Its special long carbon chain guides the lamellar structure of Na-FER molecular sieves, resulting in smaller crystal structures. During the preparation process, micropores and mesopores are generated simultaneously, which greatly increases the specific surface area of ​​the molecular sieve, enhances the adsorption of rutin by the molecular sieve, and exposes more active sites on the molecular sieve, which is beneficial for rutin to carry out electrocatalytic reactions on sensors.

[0015] In this invention, a carbon-chain organic compound serves as a template agent, which can regulate the synthesis of sheet-like FER molecular sieves. The FER molecular sieve primarily functions as a catalyst in this invention, adsorbing rutin molecules and catalyzing their electrocatalytic activity. Furthermore, the sheet-like FER molecular sieve obtained in this invention is a material with a high specific surface area, numerous catalytic sites, large adsorption capacity, and excellent molecular mass transfer and diffusion properties, making it widely applicable in catalysis and adsorption.

[0016] Due to the weak conductivity of layered FER molecular sieves, their electrochemical response in electrochemical catalysis is very weak, resulting in indistinct oxidation peaks and poor sensitivity, making them unsuitable for direct detection of rutin. Therefore, titanium is doped into FER molecular sieves to impart a certain electrocatalytic oxidation ability for rutin. The introduction of titanium enhances the conductivity of the molecular sieve, exposing more active sites and thus improving its catalytic performance. Furthermore, the modification with metal ions does not significantly alter its original morphology and pore structure.

[0017] The preparation process of the carbon chain organic compound includes: a reverse substitution reaction of 4,4-biphenylphenol with a halogenated long-chain alkane in an inert gas to obtain a precursor, and a reverse substitution reaction of the precursor with ethylenediamine to obtain the carbon chain organic compound.

[0018] Specifically, the structural formula of the precursor is: X-(CH2) n -O-(p-C6H4)2-O-(CH2) n -X; where n is 10 to 16, and X is one of Cl, I, or Br.

[0019] Specifically, the halogenated long-chain alkane is one of 1,10-dibromodecane, 1,12-dibromododecane, and 1,16-dibromohexadecane.

[0020] Preferably, the halogenated long-chain alkane is 1,12-dibromododecane.

[0021] Preferably, the structural formula of the carbon chain organic compound is:

[0022] NH2-C2H4-NH-(CH2) 12 -O-(p-C6H4)2-O-(CH2) 12 -NH-C2H4-NH2.

[0023] This invention also protects the use of the template agent in the preparation of FER molecular sieves.

[0024] A titanium-doped sheet-like FER molecular sieve is prepared by a hydrothermal method using the organic compound as a template agent.

[0025] Specifically, the preparation method of the titanium-doped sheet-like FER molecular sieve includes the following steps:

[0026] S1. Mix aluminum source, alkali source, silicon source, template agent and water to obtain aluminosilicate gel;

[0027] S2. Mix the aluminosilicate gel with a titanium source, hydrothermally heat, and calcine to obtain the titanium-doped sheet-like FER molecular sieve;

[0028] The mass ratio of the titanium source to the aluminosilicate gel is 1:100 to 500.

[0029] Preferably, the mass ratio of the titanium source to the aluminosilicate gel is 1:200.

[0030] Specifically, the molar ratio of the aluminum source, alkali source, silicon source, template agent and water is 1:(0.4-20):(1-40):(0.02-6):(20-800).

[0031] Preferably, the molar ratio of the aluminum source, alkali source, silicon source, template agent and water is 1:(0.4-10):(4-20):(0.1-1.5):(100-400).

[0032] More preferably, the molar ratio of the aluminum source, alkali source, silicon source, template agent and water is 1:(0.5~1):(5~10):(0.2~1):(200~300).

[0033] Specifically, the temperature of the hydrothermal treatment is 130–200°C.

[0034] Specifically, the hydrothermal time is 230–250 hours.

[0035] Specifically, the calcination temperature is 450–650°C.

[0036] Specifically, the calcination time is 4 to 6 hours.

[0037] Specifically, the aluminum source is at least one of sodium aluminate, aluminum sulfate, and boehmite.

[0038] Preferably, the aluminum source is sodium aluminate.

[0039] Specifically, the alkali source is at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0040] The alkaline source is used to adjust the alkalinity of the reaction system and promote the formation of aluminosilicates.

[0041] Preferably, the alkali source is sodium hydroxide.

[0042] Specifically, the silicon source is at least one of silica sol, silica fume, sodium silicate, and tetraethyl orthosilicate.

[0043] Preferably, the silicon source is silica sol.

[0044] This invention uses silica sol as the silicon source. Silica sol is easy to precipitate crystals under hydrothermal conditions, which can improve the crystallinity of FER molecular sieves, thereby improving the acid and heat resistance and stability of molecular sieves.

[0045] Specifically, after hydrothermal treatment, the resulting product needs to undergo post-processing.

[0046] More specifically, the post-processing includes centrifugation and washing.

[0047] More specifically, the centrifugation is performed at 6000–10000 r / min for 1–5 min.

[0048] Specifically, the titanium source is at least one of titanium dioxide, titanium sulfate, and titanium nitrate.

[0049] Preferably, the titanium source is titanium dioxide.

[0050] A titanium-doped sheet-like FER molecular sieve-supported chitosan composite material, the preparation method of which includes the following steps:

[0051] The titanium-doped sheet FER molecular sieve was dispersed in an aqueous solution of acetic acid and chitosan to obtain the titanium-doped sheet FER molecular sieve-supported chitosan composite material.

[0052] Specifically, the mass ratio of the titanium-doped sheet FER molecular sieve, chitosan, acetic acid, and water is 1:(0.6-1.5):(0.1-0.6):(600-1500).

[0053] An electrochemical sensor comprising an electrode and a titanium-doped FER molecular sieve-supported chitosan composite material.

[0054] More specifically, the electrode is one of glassy carbon electrode, graphite electrode, carbon electrode, and carbon fiber electrode.

[0055] Preferably, the electrode is a glassy carbon electrode (GCE).

[0056] More specifically, using the electrode as a substrate, a titanium-doped sheet-like FER molecular sieve-supported chitosan composite material is used to modify the electrode (CS). The modified electrode is an electrochemical sensor based on titanium-doped sheet-like FER molecular sieve-supported chitosan (also referred to as the CS / Ti / FER / GCE electrode in this invention).

[0057] An electrode modified with a titanium-doped layered FER molecular sieve-supported chitosan composite material exhibits a significant electrocatalytic oxidation effect on rutin. During electrochemical detection, rutin undergoes an oxidation reaction on the modified electrode surface, generating corresponding oxidation products. Due to the modification with the aforementioned composite material, the electrocatalytic activity of the electrode surface is enhanced, making the oxidation reaction of rutin easier to occur, thereby improving the sensitivity and selectivity of the sensor for rutin detection.

[0058] Furthermore, rutin has a high oxidation potential on bare electrodes, making it susceptible to interference from other substances in the sample. Modifying the electrode with the aforementioned composite material lowers the oxidation potential of rutin, allowing it to oxidize at a lower potential, reducing competition for oxidation with other substances, and improving the sensor's specificity.

[0059] Therefore, this invention uses titanium-doped layered FER molecular sieves to support chitosan composite material to modify the electrode. The modified electrode has a significant catalytic oxidation effect on rutin, which can significantly improve the sensitivity of rutin detection and increase the linear range of rutin concentration. The linear range of rutin concentration detection reaches 0.1 to 10 μmol / L, with a wide concentration detection range, low detection limit, high sensitivity, good stability, and high repeatability and selectivity.

[0060] More specifically, the method for preparing the electrochemical sensor is as follows:

[0061] A titanium-doped sheet FER molecular sieve-supported chitosan composite material was prepared into a suspension and coated onto the electrode surface to obtain the electrochemical sensor.

[0062] A three-electrode system comprising a reference electrode, a counter electrode, and a working electrode, wherein the working electrode is the electrochemical sensor.

[0063] This three-electrode system can be used for the accurate detection of rutin content in body fluids.

[0064] Specifically, the reference electrode is a saturated calomel electrode, and the counter electrode is a platinum wire electrode.

[0065] This invention also protects the application of the titanium-doped sheet FER molecular sieve or the titanium-doped sheet FER molecular sieve-supported chitosan composite material or the electrochemical sensor or the three-electrode system in the detection of rutin.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] (1) This invention provides a novel template agent and a titanium-doped sheet-like FER molecular sieve synthesized by controlling the specific ratio of raw materials. The special long carbon chain of the template agent guides the sheet-like structure of the Na-FER molecular sieve, resulting in a smaller crystal structure for the FER molecular sieve. During the preparation process, micropores and mesopores are generated simultaneously, which greatly increases the specific surface area of ​​the molecular sieve and improves the adsorption performance of the molecular sieve for rutin.

[0068] (2) The titanium-doped sheet FER molecular sieve prepared by the present invention enhances the conductivity of the molecular sieve by titanium doping, exposes more active sites in the molecular sieve, enhances the catalytic performance of the molecular sieve, and is conducive to the electrocatalytic reaction of rutin on the sensor.

[0069] (3) In this invention, a titanium-doped sheet FER molecular sieve-supported chitosan composite material is used to modify the electrode (GCE) and construct a rutin electrochemical sensor. The rutin electrochemical sensor is used for the detection and analysis of rutin tablets. The results show that the obtained electrochemical sensor has a linear range of 0.1 to 10 μmol / L for rutin detection. It has a wide concentration detection range, high detection sensitivity, accuracy, repeatability and selectivity, low detection limit and good stability.

[0070] (4) The rutin electrochemical sensor prepared by the present invention is easy to operate and inexpensive. It can realize timely monitoring of rutin in food and medicine and is of great significance for the prevention of various related diseases. Attached Figure Description

[0071] Figure 1 The image shows the proton NMR spectrum of the template agent.

[0072] Figure 2 The images show SEM images of the sheet-like FER molecular sieve and the titanium-doped sheet-like FER molecular sieve in Example 1.

[0073] Figures (a), (b), (c), and (d) show sheet-like FER molecular sieves, while Figures (e) and (f) show titanium-doped sheet-like FER molecular sieves from Example 1. The magnification of Figure (a) is 5000x, Figure (b) is 10000x, Figure (c) is 30000x, Figure (d) is 60000x, Figure (e) is 10000x, and Figure (f) is 30000x.

[0074] Figure 3(a) is the small-angle X-ray diffraction pattern of the sheet-like FER molecular sieve at 0-5°. Figure 3 (b) X-ray diffraction patterns of the sheet FER molecular sieve and the titanium-doped sheet FER molecular sieve prepared in Example 1 at 5-40°.

[0075] Figure 4 The voltammetric curves of the CS / Ti / FER / GCE electrode (b) and the bare GCE electrode (a) prepared in Example 1 in PBS solution containing 50 μmol / L rutin at pH=3 are shown.

[0076] Figure 5 The figure shows the differential pulse voltammetry curves of the CS / Ti / FER / GCE electrode prepared in Example 1 in rutin standard solutions of different concentrations. The inset is a statistical graph of the linear relationship between its oxidation peak current and concentration.

[0077] Figure 6 This is a statistical chart showing the data for verifying the selectivity of the CS / Ti / FER / GCE electrode prepared in Example 1 for rutin.

[0078] Figure 7 This is a statistical chart showing the reproducibility verification of rutin by the CS / Ti / FER / GCE electrode prepared in Example 1.

[0079] Figure 8 This is a statistical chart showing the data on the stability of rutin on the CS / Ti / FER / GCE electrode prepared in Example 1. Detailed Implementation

[0080] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0081] The sources of raw materials used in the comparative examples and embodiments of this invention are as follows: rutin standard samples were purchased from Maclean's Ltd., compound rutin tablets were purchased from World Trade Center Pharmaceutical (Jiangsu) Co., Ltd., chitosan was purchased from Maclean's Ltd., titanium dioxide was purchased from Merrill Ltd., and phosphate buffer solutions (PBS) of different pH values ​​were prepared by mixing Na2HPO4 and NaH2PO4 in different proportions. Buffer solutions with pH < 5 were prepared by adjusting the pH with NaH2PO4 and then adjusting the pH with hydrochloric acid. All reagents were analytical grade, and all solutions were prepared with deionized water.

[0082] The structural formula of the carbon-chain organic compound (i.e., template agent) used in the embodiments of the present invention is as follows:

[0083] NH2-C2H4-NH-(CH2) 12 -O-(p-C6H4)2-O-(CH2) 12 -NH-C2H4-NH2;

[0084] The above-mentioned carbon-chain organic compounds can be synthesized by the following methods:

[0085] S1. Dissolve 10 mmol of 4,4-biphenylphenol in 80 ml of anhydrous ethanol containing 20 mmol of potassium hydroxide, and add 60 mmol of 1,12-dibromododecane. Reflux at 80 °C for 20 hours, filter while hot, wash three times with ethanol, filter again, collect the filtered product, and dry in a vacuum oven at 50 °C for 12 hours to obtain the precursor Br-(CH2). 12 -O-(p-C6H4)2-O-(CH2) 12 -Br.

[0086] S2. Mix 20 mmol of the precursor and 250 mmol of ethylenediamine into a 1:1 acetonitrile / toluene solution (25 ml each). Stir at 70 °C under N2 atmosphere for 10 hours to obtain the product. Wash the product three times with diethyl ether and filter. Collect the filtered product and dry it in a vacuum oven at 50 °C for 12 hours to obtain the template agent NH2-C2H4-NH-(CH2). 12 -O-(p-C6H4)2-O-(CH2) 12 -NH-C2H4-NH2 has a relative molecular mass of 639.0214. Its NMR spectrum is shown below. Figure 1 As shown.

[0087] 1 The H NMR spectrum results are as follows: 1 H NMR (400MHz, CDCl3), δ (ppm): δ7.45 (d, 4H, Ar-H), 6.94 (d, 4H, H-Ar-O), 3.98 ( t, 4H, -OCH2), 2.80 (t, 2H, -NH-), 2.75 (s, 8H, -N-(CH2)2-N-), 2.66 (t, 2H, -N- CH2), 2.60 (t, 2H, -N-CH2-), 1.79 (q, 4H, -NH2), 1.49 (s, 4H, -N-CH2-CH2), 1.4 7(s, 4H, Ar-O-(CH2)2-CH2), 1.44(s, 4H, Ar-O-CH2-CH2), 1.28(s, 28H, -CH2-).

[0088] As can be seen from the NMR spectrum, the template agent of this invention has peaks at the key peak positions, indicating that it has been successfully synthesized; there are also a few impurity peaks in the figure, which may be due to a small amount of impurities in the sample.

[0089] A layered FER molecular sieve, the preparation method of which includes the following steps:

[0090] S1. Take 16g of deionized water, add 0.128g of sodium hydroxide and 0.308g of sodium aluminate, stir for 20min, then add 5.72g of silica sol and 0.688g of the above template agent, mix and stir thoroughly, and magnetically stir at 25℃ for 10h to obtain aluminosilicate gel. The molar ratio of sodium aluminate, sodium hydroxide, silica sol, water and template agent is 1:0.85:7.6:235:0.28.

[0091] S1. The aluminosilicate gel obtained in step S1 is transferred to a stainless steel autoclave lined with Teflon and hydrothermally reacted at 180°C for 10 days. After centrifugation at 9000 r / min for 3 min, the product is washed and collected. It is then dried at 120°C for 12 h and calcined at 550°C for 6 h to obtain the sheet-like FER molecular sieve.

[0092] Example 1

[0093] This embodiment provides a titanium-doped sheet-like FER molecular sieve, the preparation method of which includes the following steps:

[0094] S1. Take 16g of deionized water, add 0.128g of sodium hydroxide and 0.308g of sodium aluminate, stir for 20min, then add 5.72g of silica sol and 0.688g of template agent, mix and stir thoroughly to obtain aluminosilicate gel. The molar ratio of sodium aluminate, sodium hydroxide, silica sol, water and template agent is 1:0.85:7.6:235:0.28.

[0095] S2. Mix TiO2 with the aluminosilicate gel obtained in step S1, and magnetically stir at 25°C for 10 h. The mass ratio of titanium dioxide to aluminosilicate gel is 1:200. Transfer the mixture to a stainless steel autoclave lined with Teflon and hydrothermally react at 180°C for 10 days. After centrifugation at 9000 r / min for 3 min, wash and collect the product. Dry at 120°C for 12 h, and then calcine at 550°C for 6 h to obtain titanium-doped sheet-like FER molecular sieve.

[0096] This embodiment provides a titanium-doped layered FER molecular sieve-supported chitosan composite material, the preparation method of which includes the following steps:

[0097] Take 10 mg of titanium-doped sheet FER molecular sieve powder and disperse it in 10 mL of aqueous solution of acetic acid and chitosan. Disperse it ultrasonically for 30 min to obtain a suspension of the titanium-doped sheet FER molecular sieve-supported chitosan composite material.

[0098] This embodiment provides an electrochemical sensor, the preparation method of which includes the following steps:

[0099] S1. Polish the glassy carbon electrode with a diameter of 3 mm with Al2O3 polishing powder, then ultrasonically clean it in deionized water and anhydrous ethanol for 30 min each, and dry it at room temperature.

[0100] S2. Take 10 μL of the suspension of titanium-doped sheet FER molecular sieve-supported chitosan composite material and drop it onto the treated glassy carbon electrode (GCE). Let it air dry to obtain an electrochemical sensor based on titanium-doped sheet FER molecular sieve-supported chitosan (also known as CS / Ti / FER / GCE electrode).

[0101] Example 2

[0102] This embodiment provides a titanium-doped sheet-like FER molecular sieve, which is prepared in the same way as in Example 1, except that the amount of template agent added in step S1 is 0.917g, and the molar ratio of sodium aluminate, sodium hydroxide, silica sol, water and template agent is 1:0.85:7.6:235:0.37.

[0103] This embodiment provides a titanium-doped sheet FER molecular sieve-supported chitosan composite material and an electrochemical sensor. The preparation method is the same as that in Example 1, except that the titanium-doped sheet FER molecular sieve of this embodiment is used.

[0104] Example 3

[0105] This embodiment provides a titanium-doped sheet-like FER molecular sieve, which is prepared in the same way as in Example 1, except that the amount of template agent added in step S1 is 1.147 g, and the molar ratio of sodium aluminate, sodium hydroxide, silica sol, water and template agent is 1:0.85:7.6:235:0.47.

[0106] This embodiment provides a titanium-doped sheet FER molecular sieve-supported chitosan composite material and an electrochemical sensor. The preparation method is the same as that in Example 1, except that the titanium-doped sheet FER molecular sieve of this embodiment is used.

[0107] Example 4

[0108] This embodiment provides a construction of a three-electrode system: using a three-electrode system, with the titanium-doped sheet FER molecular sieve-supported chitosan electrochemical sensor obtained in Example 1 as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum wire electrode as the counter electrode.

[0109] Comparative Example 1

[0110] This comparative example provides a FER molecular sieve, using ethylenediamine as the template agent. The preparation method is referenced in: Chen Xiaoxin. Hydrothermal synthesis and characterization of magnesium-alkali zeolite in two different systems [J]. Chemical Education, 2015, 36(18):21-25.

[0111] The reaction process was as follows: 7.16 g of deionized water and 1 mL of ethylenediamine were added to a 50 mL plastic beaker and mixed thoroughly under magnetic stirring for 5 min. Then, 0.01 g of sodium hydroxide and 0.14 g of sodium aluminate were added to the reaction system, and the mixture was magnetically stirred for 30 min. Finally, 1.3 mL of silica sol (40% SiO2 content) was slowly added dropwise to the reaction system under magnetic stirring, and stirring was continued for 1 h. The resulting reaction sol had the composition of SiO2·0.15NaAlO2·0.021NaOH·1.33ethylenediamine·39.60H2O. The reaction mixture from the 50 mL plastic beaker was transferred to a reaction vessel lined with polytetrafluoroethylene (PTFE). After tightening the reaction vessel, it was placed in an oven at 180 °C for crystallization for 240 h. After the crystallization reaction of the product is completed, the reactor is cooled to room temperature. The product is filtered, washed with deionized water until the pH is neutral, and then dried naturally. The product is calcined at 550℃ for 6 hours and then automatically cooled to room temperature.

[0112] Performance testing

[0113] 1. Performance characterization of molecular sieves

[0114] (1) SEM testing

[0115] The sheet-like FER molecular sieve and the titanium-doped sheet-like FER molecular sieve prepared in Example 1 were analyzed using a Merlin field emission scanning electron microscope from Zeiss GmbH, Germany. The results are as follows: Figure 2 As shown, the FER molecular sieve synthesized by the self-made template agent in this invention has a distinct small plate-like structure. Figure 2 (e) and (f) show that the morphology of the titanium-doped FER molecular sieve did not change after the process.

[0116] (2) X-ray diffraction test

[0117] The sheet-like FER molecular sieve and the titanium-doped sheet-like FER molecular sieve prepared in Example 1 were characterized using a Bruker D8 Advance X-ray diffractometer (Germany). The results are as follows: Figure 3As shown, the standard diffraction peaks of FER molecular sieves are observed in the 2θ range of 5-40°, and diffraction peaks are present in the 2θ range of 0-5°, indicating that the sheet-like FER molecular sieve obtained in this invention has a mesoporous structure. Furthermore, comparing the FER molecular sieve and the titanium-doped sheet-like FER molecular sieve with the FER standard card, the XRD pattern of the titanium-doped sheet-like FER molecular sieve showed no significant change, indicating that titanium is well dispersed within the molecular sieve framework.

[0118] (3) BET test

[0119] The layered FER molecular sieve, the titanium-doped layered FER molecular sieve prepared in Example 1, and the FER molecular sieve prepared in Comparative Example 1 were characterized using a Micromeritics ASAP 2460 microscope. The results are shown in Table 1.

[0120] Table 1 Pore structure parameters of molecular sieves

[0121]

[0122] Table 1 shows that N2 adsorption-desorption isotherms were performed on the sheet-like FER molecular sieve and the titanium-doped sheet-like FER molecular sieve prepared in Example 1, and the results were compared with those of the FER molecular sieve prepared using ethylenediamine as a template agent in Comparative Example 1. The results are shown in Table 1, indicating that the sheet-like FER molecular sieve synthesized using the self-made template agent has a larger specific surface area, reaching 312.3327 m². 2 ·g -1 The 301m of FER molecular sieve prepared using ethylenediamine as a template agent was greater than that of ethylenediamine. 2 ·g -1 Furthermore, the pore volume of the layered molecular sieve is significantly higher than that of conventional molecular sieves, and the FER molecular sieve prepared by this invention has a large number of mesopores. After passing through the titanium-doped layered FER molecular sieve, the specific surface area decreases slightly, indicating that titanium has successfully entered the molecular sieve framework. Moreover, the titanium-doped layered FER molecular sieve has a large specific surface area and high adsorption capacity, which is beneficial to the adsorption of rutin molecules and the rapid progress of catalytic reactions.

[0123] 2. Performance determination of a titanium-doped layered FER molecular sieve-supported chitosan electrochemical sensor

[0124] (1) Cyclic voltammetry test

[0125] Cyclic voltammetry was performed on the three-electrode system of Example 5 using a CHI660E electrochemical workstation from Shanghai Huayi Instruments Co., Ltd. The results are as follows: Figure 4As shown, in a PBS solution containing 50 μmol / L rutin, the titanium-doped sheet FER molecular sieve-supported chitosan electrochemical sensor (b) has a higher oxidation peak than the sheet FER molecular sieve-supported chitosan electrochemical sensor (a) under a potential of 0.52 V, indicating that the titanium-doped sheet FER molecular sieve electrode has a better electrochemical response to rutin.

[0126] (2) Differential pulse voltammetry test

[0127] In a three-electrode system, differential pulse voltammetry was used to test rutin standard solutions of different concentrations, such as... Figure 5 As shown, within the potential range of 0.2–0.8 V, when the concentration of rutin varies from 0.1 to 10 μmol / L, the peak current significantly increases with increasing concentration. The square root of the response current of the catalytic reaction is linearly related to the square root of the rutin concentration, with the relationship being Y = 0.20884X + 6.25155, and the correlation coefficient being R. 2 =0.9912, detection limit is 0.1 μmol / L. The above results indicate that the titanium-doped FER molecular sieve-supported chitosan electrochemical sensor obtained in this invention has a wide detection linear range (0.1–10 μmol / L) and a low detection limit (0.1 μmol / L), enabling accurate detection of rutin. In contrast, the detection range of rutin by high-performance liquid chromatography (HPLC) is typically 5.0–20.0 μg / mL, and the detection range of rutin by spectrophotometry is typically 0.0022 mg / mL–0.156 mg / mL. The titanium-doped FER molecular sieve-supported chitosan electrochemical sensor obtained in this invention has a wide detection linear range (0.1–10 μmol / L) and a detection limit far lower than that of commercially available methods. Therefore, this invention can meet the detection requirements for low rutin concentrations.

[0128] (3) Selectivity, reproducibility and stability tests

[0129] In a three-electrode system, an interfering substance was added to a PBS solution containing 10 μmol / L rutin before detection. The interfering substance was Cu. 2+ K + Zn 2+ The study included L-tyrosine, L-tryptophan, glucose, and riboflavin, with the interfering substance concentration being 50 times that of rutin, thereby verifying the selectivity of the titanium-doped sheet-like FER molecular sieve-supported chitosan electrochemical sensor (i.e., CS / Ti / FER / GCE electrode) obtained in Example 1. The results are as follows: Figure 6 As shown, the current magnitude did not change significantly after adding 50 times the concentration of interfering ions to the PBS solution of rutin, indicating that the titanium-doped sheet FER molecular sieve-supported chitosan electrochemical sensor obtained in this invention has good selectivity.

[0130] The rutin solution was measured six times at different times using the same CS / Ti / FER / GCE electrode obtained in Example 1. The results are as follows: Figure 7 As shown, the current values ​​obtained in the six tests were basically similar, indicating that the electrode has good reproducibility.

[0131] Figure 8 This is a statistical graph showing the data for verifying the stability of rutin on the CS / Ti / FER / GCE electrode prepared in Example 1. The test time was 40 hours, and the current values ​​were basically similar within these 40 hours, indicating that the electrode has good stability.

[0132] (4) Accuracy test

[0133] In the three-electrode system, the actual compound rutin tablets were diluted with buffer solution instead of the rutin standard solution for detection, and the results are shown in Table 1. The sample concentrations in Table 1 were calculated and prepared according to the rutin content per tablet specified in the compound rutin tablet instructions. The concentration of the rutin sample after dilution of the actual compound rutin tablets was 10 μmol / L. The recovery rate of rutin concentration was tested to be between 93.4% and 96.7%, with an RSD of 5.4%. This indicates that the test accuracy is good and meets the testing requirements. This also shows that the CS / Ti / FER / GCE electrode obtained in this invention has good rutin detection performance.

[0134] Table 2

[0135]

[0136] The performance characterization results of the electrochemical sensors obtained in Examples 2 and 3 are basically the same as those in Example 1, and will not be repeated here.

[0137] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A carbon-chain organic compound, characterized in that, The structural formula of the organic compound is: NH2-C2H4-NH-(CH2) n -O-(p-C6H4)2-O-(CH2) n -NH-C2H4-NH2; where n is 10~16.

2. The application of the organic compound as described in claim 1 in the preparation of FER molecular sieves.

3. A titanium-doped sheet-like FER molecular sieve, characterized in that, It is prepared by a hydrothermal method using the organic compound of claim 1 as a template agent; The preparation method of the titanium-doped sheet-like FER molecular sieve includes the following steps: S1. Mix aluminum source, alkali source, silicon source, template agent and water to obtain aluminosilicate gel; S2. Mix the aluminosilicate gel with a titanium source, hydrothermally heat, and calcine to obtain the titanium-doped sheet-like FER molecular sieve; The mass ratio of the titanium source to the aluminosilicate gel is 1:100~500; the molar ratio of the aluminum source, alkali source, silicon source, template agent and water is 1:(0.4~20):(1~40):(0.02~6):(20~800); the hydrothermal temperature is 130~200 ℃.

4. A titanium-doped layered FER molecular sieve-supported chitosan composite material, characterized in that, Its preparation method includes the following steps: The titanium-doped sheet FER molecular sieve of claim 3 is dispersed in an aqueous solution of acetic acid and chitosan to obtain the titanium-doped sheet FER molecular sieve-supported chitosan composite material.

5. An electrochemical sensor, characterized in that, The electrochemical sensor includes electrodes and the titanium-doped sheet FER molecular sieve-supported chitosan composite material as described in claim 4.

6. A three-electrode system, characterized in that, The three-electrode system includes a reference electrode, a counter electrode, and a working electrode, wherein the working electrode is the electrochemical sensor described in claim 5.

7. The application of the titanium-doped sheet FER molecular sieve of claim 3, the titanium-doped sheet FER molecular sieve supported on chitosan composite material of claim 4, the electrochemical sensor of claim 5, or the three-electrode system of claim 6 in the detection of rutin.

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