Preparation and application of vitamin B1 determination electrode

Abstract

The invention relates to the technical field of electrochemical analysis and detection, in particular to preparation and application methods of an electrode for measuring vitamin B1. The invention aims to prepare a nano-silver / multi-walled carbon nanotube modified electrode by using an electrochemical deposition method, and to determine the content of vitamin B1 by using the nano-silver / multi-walled carbon nanotube modified electrode. According to the technical scheme, nano-silver particles are deposited on the surface of a substrate electrode through an electrochemical method, then multi-walled carbon nanotubes are inlaid on the surface of the substrate electrode in a covalent self-assembly mode, and the nano-silver / multi-walled carbon nanotube modified electrode is prepared. Compared with a bare glassy carbon electrode, a single nano-silver electrode and a single multi-walled carbon nanotube electrode, the electrode has better catalytic oxidation effect and selectivity on vitamin B1. The vitamin B1 is determined by cyclic voltammetry. The substance has a good linear relationship with a peak current in a concentration range of 3-40 mmol / L, and R2 is equal to 0.96. And the determination result of the standard addition recovery rate of the sample is 96%. The method for measuring the content of vitamin B1 in the sample through the electrode is easy to operate, high in sensitivity and low in analysis cost.

Description

Technical Field

[0001] The present invention relates to the technical field of drug content determination, and in particular to the preparation and application of a novel electrode that can be used for vitamin B1 determination. Background Art

[0002] Vitamin B1 (VB1), also known as thiamine or anti-neuritisin, is a B vitamin composed of a pyrimidine ring and a thiazole ring. It is a white crystalline powder with a slight characteristic odor, a bitter taste, and is deliquescent. Its chemical name is 3-[(4-amino-2-methyl-5-pyrimidinyl)-methyl]-5-(2-hydroxyethyl)-4-methylthiazolium chloride hydrochloride. Vitamin B1 plays a role in maintaining normal glucose metabolism and nerve conduction. It is commonly used to prevent and treat vitamin B1 deficiency symptoms such as beriberi, neuritis, and indigestion. In recent years, research has also focused on the effects of vitamin B1 on brain energy metabolism.

[0003] Conventional methods for determining vitamin B1 content primarily rely on HPLC and fluorescence methods. Currently, these methods suffer from disadvantages such as high analytical costs, poor selectivity, and complex procedures. In contrast, electrochemical analysis offers higher sensitivity and selectivity, along with simplicity, speed, high automation, and low instrument costs. Consequently, it has gained widespread application in the life sciences field.

[0004] In recent years, the physical structure, electrical conductivity, and catalytic activity of carbon nanotubes and silver nanoparticles have made them excellent electrode modification materials, finding widespread application in a wide range of fields, including environmental, food, and pharmaceutical analysis. Electrochemical sensors constructed by combining multi-walled carbon nanotubes with other materials are also increasingly being used in the detection of various small biomolecules.

[0005] This invention utilizes an electrochemical method to deposit silver nanoparticles on the surface of a substrate electrode, then covalently self-assembles multi-walled carbon nanotubes onto this surface to create a nanosilver / multi-walled carbon nanotube-modified electrode. Compared to bare glassy carbon electrodes, single nanosilver electrodes, and single multi-walled carbon nanotube electrodes, this electrode exhibits superior catalytic oxidation of vitamin B1. The method for determining vitamin B1 content in samples using this electrode is simple to operate, highly sensitive, and low in cost. Summary of the Invention

[0006] The purpose of the present invention is to prepare a nanosilver / multi-walled carbon nanotube modified glassy carbon electrode and establish a new method for determining vitamin B1.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a three-electrode system consisting of a nanosilver / MWNTs-modified glassy carbon electrode as a working electrode, a platinum wire electrode as a counter electrode, and a silver / saturated silver chloride electrode as a reference electrode is sequentially placed in a standard solution of vitamin B1 with a concentration of 3 to 30 mmol / L. Cyclic voltammetry curves are recorded at a scan rate of 50 mV / s between -0.6 and 0.6 V using potassium hydrogen phthalate (pH 4.0) as a buffer solution, and the content of the active ingredient in the sample is calculated using a standard curve method. The specific steps include:

[0008] (1) Preparation of electrodes for vitamin B1 determination: pretreatment of glassy carbon electrodes, preparation of silver nanoparticle layers by electrodeposition, carboxylation of multi-walled carbon nanotubes, and self-assembly on the surface of silver nanoparticle films;

[0009] (2) Selection of assay conditions: optimization of modification layer materials, optimization of buffer solution type and acidity, optimization of nanosilver deposition conditions, and optimization of optimal use time;

[0010] (3) Establishment of working curve: A three-electrode system is composed of a homemade vitamin B1 determination electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire electrode as the counter electrode. The three-electrode system is placed in a standard solution of vitamin B1 with a concentration in the range of 3 to 30 mmol / L. The peak of the cyclic voltammetry curve is scanned under optimized experimental conditions, and a standard curve equation for the peak current is established with the standard concentration as the variable.

[0011] (4) Determination of actual samples: Based on the labeled content of the sample, its concentration is adjusted to the linear range. The three-electrode system is placed in the treated sample solution under the same experimental conditions as those used to establish the standard curve. The cyclic voltammetry method is used to scan and record the peak current. The vitamin B1 content in the sample is calculated using the standard curve equation.

[0012] (5) Spiked recovery and precision determination: Spiked recovery and relative standard deviation were determined under the same conditions as those used for preparing the standard curve.

[0013] The vitamin B1 measuring electrode prepared by this invention has good sensitivity, conductivity and selectivity, and the sample measurement process is simple and easy to operate, with low analysis cost. This invention is a convenient technology for quickly measuring the content of vitamin B1 or its active ingredient. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] Attachment Figure 1 CV curves of different electrodes in vitamin B1 standard solution;

[0016] Attachment Figure 2 CV curves of the electrode for vitamin B1 determination in different buffer solutions;

[0017] Attachment Figure 3 The CV curves of vitamin B1 on electrodes at different storage times

[0018] Attachment Figure 4 This is the CV curve of the electrode for vitamin B1 determination in standard solutions of different concentrations; DETAILED DESCRIPTION

[0019] To achieve the objectives of the invention, the present invention employs a three-electrode system consisting of a glassy carbon electrode or modified electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire as the auxiliary electrode. Both the electrochemical deposition of silver nanoparticles and the determination of vitamin B1 are performed using cyclic voltammetry, with the base electrode modified with silver nitrate and multi-walled carbon nanotubes.

[0020] Pretreatment of substrate electrode:

[0021] A glassy carbon electrode was polished on metallographic sandpaper (3000#), and then polished with 1.0, 0.3 and 0.05 μm Al2O3 powder on dry and wet suede pads, respectively. The electrode was thoroughly ultrasonically cleaned with deionized distilled water, anhydrous ethanol and deionized distilled water for 3 minutes, and then the electrode was placed in a 0.5 mol / L H2SO4 solution. Cyclic voltammetry (CV) was used to scan the potential range of -0.2 to +0.6 V at a scan speed of 100 mV / s until the curve stabilized. The electrode was taken out, rinsed with deionized water, and stored in a sealed desiccator for later use.

[0022] Preparation of nanosilver coating by electrochemical deposition:

[0023] A CS300 electrochemical workstation was used to prepare the silver nanofilm in cyclic voltammetry (CV) mode. A three-electrode system was used: a glassy carbon electrode (GCE) as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The treated GCE was placed in 10 mL of a 20 mmol / L silver nitrate solution, and the CV method was used to scan the potential range of 0 to -1 V at a scan rate of 50 mV / s until the curve stabilized. After the electrode was removed, rinsed with water, and dried with an infrared lamp for 10 minutes, a dense and stable silver nanofilm was formed on the surface of the glassy carbon electrode. Carboxylation of multi-walled carbon nanotubes and self-assembly on the silver nanocoating:

[0024] MWNTs were carboxylated by refluxing in a 1:3 V(HNO3):V(HCl) solution for 12 hours. The solution was then washed with 0.01 mol / L NaOH until the pH was near neutral, centrifuged, and dried. 5.0 mg of pretreated MWNTs were ultrasonically dispersed in 5.0 mL of DMF (N,N-dimethylformamide) for 30 minutes to obtain a stable black dispersion. The resulting black dispersion was then added dropwise to the surface of the silver nanofilm, dried under infrared light, and stored in a sealed desiccator for one week before use.

[0025] Selection of electrode preparation conditions:

[0026] Optimization of modification materials and order: Figure 1 The cyclic voltammetry curves of vitamin B1 on different working electrodes are shown in Figure 2. The electrodes prepared with different modified materials are used as working electrodes, and the response curves of 20 mmol / L vitamin B1 standard solution are scanned by CV method at a scanning speed of 50 mV / s in the potential range of -0.6 to +0.6 V. Figure 1 As shown, the bare glassy carbon electrode (curve a) and the electrode modified with only MWNTs (curve b) showed almost no response to vitamin B1. The MWNTs / Ag modified electrode (curve c), the electrode modified with only nanosilver (curve d), and the Ag / MWNTs modified electrode (curve e) all showed reduction peaks, and the signal response increased in descending order. This indicates that the Ag / MWNTs modified electrode has a higher sensitivity for vitamin B1 detection than the other electrodes.

[0027] Optimization of scan rate: The scan rate was varied within the range of 10 to 150 mV / s. The results showed that the peak current value was the highest at 50 mV / s.

[0028] Optimization of buffer solution: According to the electrochemical conditions described above, comparative experiments were conducted on 20 mmol / L vitamin B1 standard solution in three different buffer solutions. Figure 2 These are the CV curves of the vitamin B1 measuring electrode in different buffer solutions. Curve a corresponds to PBS buffer, curve b corresponds to boric acid buffer, and curve c corresponds to potassium hydrogen phthalate buffer.

[0029] like Figure 2 As shown in the figure, vitamin B1 shows a good redox peak in potassium hydrogen phthalate buffer solution, and the electrochemical response intensity is much better than that of the other two base solutions.

[0030] Optimization of the standing time after electrode preparation: The modified nanosilver / multi-walled carbon nanotube electrode was placed in a sealed container at 15°C, and the CV response curves of the electrode after 20 m mol / L vitamin B1 were measured after 1 day and 15 days of storage. Figure 3 As shown in the figure, the electrochemical response intensity of vitamin B1 increases significantly with the increase of electrode static time. Curve a in the figure is the Ag / MWNTs modified electrode stored for 1 day, and curve b is the Ag / MWNTs modified electrode stored for 15 days.

[0031] How to use the vitamin B1 determination electrode:

[0032] Establishment of the standard curve: Under optimized experimental conditions, standard solutions of vitamin B1 at concentrations of 2, 3, 5, 10, 15, 20, 30, and 40 mmol / L were tested in sequence. The results showed that the reduction peak current of vitamin B1 had a good linear relationship with its concentration in the range of 3 to 40 mmol / L. The linear equation was: I = 6.428 × 10 -7 c-2.488×10 -5 (I:A, c:mmol / L,)R 2 =0.964.

[0033] Attachment Figure 4 The CV curves of the vitamin B1 electrode in standard solutions of different concentrations are shown in Figure 1. Curves a through e correspond to vitamin B1 concentrations of 5, 10, 15, 20, and 30 m mol / L, respectively.

[0034] Sample determination and recovery experiment: Take 20 vitamin B1 tablets with a labeled content of 10 mg, dissolve them, filter them, and then dissolve them into 50 ml of test solution (the concentration prepared according to the labeled dosage is approximately 12 mmol / L). Under the same conditions as those used to draw the standard curve, the relative standard deviation (RSD) value of the same sample repeated 5 times is 3.5%. The average content of each tablet is converted to 9.63 mg. Vitamin B1 standard solution is added to this sample solution in sequence to change its concentration to 15, 20, and 30 mmol / L, respectively. The average spiked recovery is 96.3%.

Claims

1. A method for preparing an electrode for measuring vitamin B1 and its application, wherein the electrode is prepared using an electrochemical deposition method. Specifically, a glassy carbon electrode is used as the working electrode, a platinum wire electrode is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. A pre-polished, activated, and cleaned glassy carbon electrode is placed in 10 mL of a 10-30 mmol / L silver nitrate solution and scanned using cyclic voltammetry (CV) in the potential range of 0 to -1 V at a scan rate of 40 to 60 mV / s until stable. The electrode is removed, rinsed with deionized water, and dried under an infrared lamp for 10 minutes to obtain a nanosilver-modified glassy carbon electrode.

2. The method for preparing an electrode for measuring vitamin B1 as claimed in claim 1 is characterized in that 5.0 mg of carboxylated MWNTs are weighed and ultrasonically dispersed in 4.0-6.0 mL of N,N-dimethylformamide for 30 minutes, and then 1 mL of the dispersion is dropwise added to the surface of a nanosilver-modified glassy carbon electrode. After drying with an infrared lamp for 10 minutes, the electrode is sealed and stored at room temperature for 10-15 days before use.

3. The application method of the vitamin B1 determination electrode as claimed in claim 1 is characterized in that a three-electrode system consisting of a nanosilver / MWNTs modified glassy carbon electrode as a working electrode, a platinum wire electrode as a counter electrode, and a silver / saturated silver chloride electrode as a reference electrode is sequentially placed in a 3-30 mol / L vitamin B1 standard solution, and a cyclic voltammetry curve is recorded at a scanning rate of 40-60 mV / s at a voltage between -0.6 and 0.6 V using potassium hydrogen phthalate with a pH of 3.8-4.2 as a buffer solution, and the content of the active ingredient in the sample is calculated using a standard curve method.

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