A method for simultaneous detection of dopamine and epinephrine
By using square wave cyclic voltammetry and graphene electrodes, the problem of difficulty in simultaneously detecting dopamine and adrenaline in existing technologies was solved, and efficient, sensitive, and interference-resistant simultaneous determination of the two in biological samples was achieved.
Patent Information
- Application Number
- CN202310441396.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-21
- Publication Date
- 2025-09-16
- Estimated Expiration
- 2043-04-21
AI Technical Summary
Existing technologies make it difficult to detect dopamine and epinephrine simultaneously, efficiently and sensitively in biological samples, and there are problems with the complex synthesis of modification materials and the irreproducibility of detection results.
Square wave cyclic voltammetry combined with a graphene electrode was used to detect the electrochemical response signals of dopamine and adrenaline during their redox processes, thereby achieving simultaneous quantitative analysis of both.
The method realizes the simultaneous determination of dopamine and adrenaline concentrations in biological samples, has the advantages of simplicity, efficiency, high sensitivity and strong anti-interference ability, and is suitable for on-site real-time detection.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electrochemical analysis and detection, and in particular to a method for simultaneously detecting dopamine and adrenaline. Background Art
[0002] Dopamine (DA) and epinephrine (EP) are important neurotransmitters in mammals, transmitting information throughout the brain and body. The brain uses these neurotransmitters to stimulate the heart, control breathing, and digest food. Abnormal levels of dopamine and epinephrine in the body can lead to a variety of diseases, such as Parkinson's disease, depression, schizophrenia, myocardial infarction, and pheochromocytoma. Therefore, measuring dopamine and epinephrine is crucial.
[0003] Currently, methods for detecting dopamine and epinephrine include high-performance liquid chromatography, mass spectrometry, chemiluminescence, spectrophotometry, and near-infrared spectroscopy. These methods require complex operating steps, and the detection instruments are expensive and bulky, making them unsuitable for on-site detection. Electrochemical methods have the advantages of high sensitivity, fast detection speed, and strong anti-interference ability. Moreover, the detection equipment can be easily miniaturized, which is conducive to on-site real-time detection and has broad application prospects. However, dopamine and epinephrine have similar chemical structures and similar oxidation peak potentials, making them difficult to distinguish using ordinary bare electrodes. Modification of the electrode surface is required, and the process of synthesizing the modified materials is often complicated and may also lead to non-reproducibility of the test results, increasing the difficulty of on-site detection and making it difficult to fully meet the requirements of practical applications.
[0004] Therefore, it is of great significance to develop a simple, efficient, sensitive, anti-interference-resistant detection method that can simultaneously determine the concentrations of dopamine and epinephrine in biological samples. Summary of the Invention
[0005] The object of the present invention is to provide a method for simultaneously detecting dopamine and epinephrine.
[0006] The technical solution adopted by the present invention is:
[0007] A method for simultaneously detecting dopamine and epinephrine comprises the following steps:
[0008] 1) preparing a series of dopamine standard solutions at different concentrations, mixing them with buffer solutions and performing voltammetry detection, and then plotting a positive reduction peak current-dopamine concentration standard curve based on the positive reduction peak current obtained by the detection; preparing a series of dopamine-epinephrine standard solutions at different concentrations, mixing them with buffer solutions and performing voltammetry detection, and then plotting a negative reduction peak current-dopamine and epinephrine total concentration standard curve based on the negative reduction peak current obtained by the detection;
[0009] 2) The sample solution to be tested is mixed with a buffer solution and then subjected to voltammetry detection to measure the positive reduction peak current and the negative reduction peak current. The dopamine concentration is then determined by referring to a standard curve of the positive reduction peak current-dopamine concentration, and the total concentration of dopamine and epinephrine is determined by referring to a standard curve of the negative reduction peak current-dopamine and epinephrine total concentration. The epinephrine concentration is then determined by subtracting the dopamine concentration from the total concentration of dopamine and epinephrine.
[0010] Preferably, the buffer solution is one of acetic acid-sodium acetate buffer solution, citric acid-sodium citrate buffer solution, boric acid-sodium borate buffer solution, sodium carbonate-sodium bicarbonate buffer solution, disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution, and disodium hydrogen phosphate-potassium dihydrogen phosphate buffer solution.
[0011] Further preferably, the buffer solution is a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution.
[0012] Preferably, the concentration of the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution is 0.005 mol / L to 3 mol / L.
[0013] Further preferably, the concentration of the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution is 0.01 mol / L to 1 mol / L.
[0014] Preferably, the pH value of the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution is 5-9.
[0015] Further preferably, the pH value of the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution is 6.6-8.2.
[0016] Preferably, the voltammetry detection is one of cyclic voltammetry detection, conventional pulse voltammetry detection, differential pulse voltammetry detection, square wave voltammetry detection, and square wave cyclic voltammetry detection.
[0017] Further preferably, the voltammetry detection is square wave cyclic voltammetry detection.
[0018] Preferably, the working electrode in the three-electrode system used in the square wave cyclic voltammetry detection is a graphene electrode, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a graphite electrode.
[0019] Preferably, the voltage range of the square wave cyclic voltammetry detection is -0.5V to 0.3V, the pulse amplitude is 20mV to 80mV, the square wave frequency is 5Hz to 30Hz, and the potential increment is 1mV to 10mV.
[0020] Preferably, the concentrations of dopamine and epinephrine in the dopamine-epinephrine standard solution are the same.
[0021] Preferably, the voltammetry detection is performed with at least three parallel tests.
[0022] The detection principle of the present invention is as follows: under neutral conditions, dopamine and adrenaline are oxidized to generate corresponding quinone substances. After deprotonation, the amine groups in these two quinone substances undergo intramolecular cyclization to form colorless amino pigments. The colorless amino pigments react chemically with the quinone substances in the solution to generate amino pigments and catecholamines. Under a certain potential, the amino pigments will be reduced to colorless amino pigments. Square wave cyclic voltammetry is used to detect the electrochemical response signals generated by dopamine and epinephrine during the redox process. According to the different intramolecular cyclization rates of dopamine and epinephrine, one or two different reduction peaks will be generated in the reverse reduction scan phase of the square wave cyclic voltammetry detection. Among them, dopamine has a reduction peak at both positive and negative potentials, while epinephrine only has a reduction peak at negative potential. When dopamine and epinephrine are detected simultaneously, the dopamine concentration can be obtained based on the reduction peak current at the positive potential, while the peak current of the reduction peak at the negative potential will increase with the increase in the concentration of the dopamine and epinephrine standard solutions added at equal concentrations. Therefore, the total concentration of dopamine and epinephrine can be obtained by using the reduction peak current at the negative potential, and the concentration of epinephrine can be obtained by subtracting the dopamine concentration, ultimately achieving simultaneous quantitative analysis of dopamine and epinephrine.
[0023] The beneficial effects of the present invention are: the method of the present invention can realize the simultaneous determination of dopamine and adrenaline concentrations in biological samples, has the advantages of simplicity, high efficiency, high sensitivity, strong anti-interference ability, etc., and is suitable for on-site real-time detection.
[0024] Specifically:
[0025] 1) The electrochemical detection method of the present invention utilizes modification-free electrodes connected to an electrochemical sensing device to simultaneously quantitatively determine dopamine and epinephrine, which is simple to operate and highly sensitive;
[0026] 2) The electrochemical detection method of the present invention uses square wave cyclic voltammetry as an analytical technique. This technique combines the advantages of cyclic voltammetry and square wave voltammetry, effectively reducing background current and improving detection sensitivity while also demonstrating the electrochemical behavior of substances.
[0027] 3) The electrochemical detection method of the present invention can achieve simultaneous determination of dopamine and adrenaline concentrations in biological samples, which helps to understand the impact of abnormal dopamine and adrenaline levels on biological diseases. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 Figure 3 shows the square wave cyclic voltammetry curves of dopamine and epinephrine when detected separately and simultaneously.
[0029] Figure 2 Square wave cyclic voltammetry curves of dopamine at different concentrations.
[0030] Figure 3 Square wave cyclic voltammetry curves of epinephrine at different concentrations.
[0031] Figure 4 Square wave cyclic voltammetry curves of dopamine-epinephrine at different concentrations.
[0032] Figure 5 This is the square wave cyclic voltammetry curve of dopamine-epinephrine under the interference of ascorbic acid.
[0033] Figure 6 This is the square wave cyclic voltammetry curve of dopamine-epinephrine under the interference of uric acid. DETAILED DESCRIPTION
[0034] The present invention will be further explained and illustrated below with reference to specific embodiments.
[0035] Example:
[0036] a) Electrochemical behavior of dopamine and epinephrine:
[0037] The testing process is as follows:
[0038] 1) Prepare 0.05 mol / L dopamine and 0.05 mol / L epinephrine standard solutions. Then, take 50 μL of each standard solution and mix it with 25 mL of 0.1 mol / L sodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution (pH = 7.0). Vortex for 90 s to obtain mixed solution A with a dopamine concentration of 100 μmol / L (denoted as 100 μM DA) and mixed solution B with a epinephrine concentration of 100 μmol / L (denoted as 100 μM EP), respectively.
[0039] 2) Prepare a dopamine-epinephrine standard solution with a dopamine concentration of 0.05 mol / L and an epinephrine concentration of 0.05 mol / L. Then, take 50 μL of the dopamine-epinephrine standard solution and mix it with 25 mL of a 0.1 mol / L, pH 7.0, sodium hydrogen phosphate disodium dihydrogen phosphate buffer solution. Vortex for 90 s to obtain a mixed solution C with a dopamine concentration of 100 μmol / L and an epinephrine concentration of 100 μmol / L (denoted as 100 μM DA + 100 μM EP).
[0040] 3) Take 50 μL of mixed solutions A to C and perform square wave cyclic voltammetry on them using a three-electrode system (graphene electrode as working electrode, Ag / AgCl electrode as reference electrode, and graphite electrode as counter electrode). The applied voltage scan range is -0.5 V to 0.3 V, the pulse amplitude is 50 mV, the square wave frequency is 15 Hz, the potential increment is 4 mV, and three parallel tests are set up. The square wave cyclic voltammetry curves of dopamine and epinephrine when detected separately and simultaneously are shown as follows: Figure 1 shown.
[0041] Depend on Figure 1 It can be seen that: 100μM dopamine has two oxidation peaks in the forward scanning process, at -0.26V and +0.14V respectively, and two reduction peaks in the reverse scanning process, at -0.29V and +0.12V respectively; 100μM epinephrine has two oxidation peaks in the forward scanning process, at -0.21V and +0.12V respectively, and only one reduction peak in the reverse scanning process, at -0.26V; 100μM dopamine and epinephrine mixed The compound exhibited two oxidation peaks during the forward scan, at -0.24 V and +0.14 V, respectively; and two reduction peaks during the reverse scan, at -0.26 V and +0.12 V, respectively; the positive potential oxidation peak corresponded to the oxidation of dopamine and epinephrine to the corresponding quinones, the positive potential reduction peak corresponded to the reduction of quinones to dopamine and epinephrine, the negative potential reduction peak corresponded to the reduction of quinones to form colorless amino pigments through intramolecular cyclization, and the negative potential oxidation peak corresponded to the oxidation of amino pigments.
[0042] b) Linear relationship between reduction peak current and dopamine and epinephrine concentrations:
[0043] The testing process is as follows:
[0044] 1) Prepare a 0.05 mol / L dopamine standard solution and a 0.05 mol / L epinephrine standard solution. Then, take 0 μL to 35 μL of each standard solution and mix them with 25 mL of 0.1 mol / L sodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution at pH 7.0. Vortex for 90 s to obtain a mixed solution A with a dopamine concentration of 0 μmol / L to 70 μmol / L (denoted as 0 μM DA to 70 μM DA) and a mixed solution B with an epinephrine concentration of 0 μmol / L to 70 μmol / L (denoted as 0 μM EP to 70 μM EP), respectively.
[0045] 2) Prepare a dopamine-epinephrine standard solution with a dopamine concentration of 0.05 mol / L and an epinephrine concentration of 0.05 mol / L. Then, take 0 μL to 35 μL of the dopamine-epinephrine standard solution and mix it with 25 mL of a 0.1 mol / L, pH 7.0, sodium hydrogen phosphate disodium dihydrogen phosphate buffer solution. Vortex for 90 seconds to obtain a mixed solution C with a dopamine concentration of 0 μmol / L to 70 μmol / L and an epinephrine concentration of 0 μmol / L to 70 μmol / L (denoted as 0 μM DA + 0 μM EP to 70 μM DA + 70 μM EP).
[0046] 3) Take 50 μL of mixed solutions A to C and perform square wave cyclic voltammetry on them using a three-electrode system (graphene electrode as working electrode, Ag / AgCl electrode as reference electrode, and graphite electrode as counter electrode). The applied voltage scan range is -0.5 V to 0.3 V, the pulse amplitude is 50 mV, the square wave frequency is 15 Hz, the potential increment is 4 mV, and three parallel experiments are set. The square wave cyclic voltammetry curves of dopamine at different concentrations are shown below. Figure 2 As shown in Figure 2, the square wave cyclic voltammetry curves of epinephrine at different concentrations are as follows: Figure 3 As shown in the figure, the square wave cyclic voltammetry curves of dopamine-epinephrine at different concentrations are shown in the figure. Figure 4 shown.
[0047] Depend on Figure 2 It can be seen that within the dopamine concentration range of 5 μmol / L to 70 μmol / L, the positive potential reduction peak current shows a good linear relationship with the concentration, and the regression equation is y = -0.2789x -4.1783, R 2 =0.9941 (y represents the positive potential reduction peak current, x represents the dopamine concentration), the negative potential reduction peak current and concentration show two linear relationships, the first regression equation (dopamine concentration is 5μmol / L~20μmol / L) is y1=-0.3256x-3.2821, R 2 =0.9969, the second regression equation (dopamine concentration is 20μmol / L~70μmol / L) is y2=-0.1152x-7.5539, R 2 =0.9908 (y1 and y2 represent the magnitude of the negative potential reduction peak current, and x represents the dopamine concentration).
[0048] Depend on Figure 3 It can be seen that within the range of adrenaline concentration of 5μmol / L to 70μmol / L, the negative potential reduction peak current also shows a good linear relationship with the concentration, and the regression equation is y=-0.1545x+0.1504, R 2 =0.9985 (y represents the magnitude of the negative potential reduction peak current, and x represents the adrenaline concentration).
[0049] Depend on Figure 4 It can be seen that: in the range of 5μmol / L to 70μmol / L for both dopamine and epinephrine concentrations (the concentrations of dopamine and epinephrine are the same), the linear relationship between the positive potential reduction peak current and the dopamine concentration is y = -0.2219x -0.5257, R 2 =0.9995 (y represents the positive potential reduction peak current, x represents the dopamine concentration). The negative potential reduction peak current also has a certain linear relationship with the dopamine and adrenaline concentrations. The fitting equation is divided into two sections. When the concentration is 5μmol / L~20μmol / L, the equation is expressed as y1=-0.3181x-0.4291, R 2 =0.9976, while when the concentration is 20μmol / L~70μmol / L, the fitting equation is y2=-0.1771x-3.3173, R 2 =0.9964 (y1 and y2 represent the magnitude of the negative potential reduction peak current, and x represents the concentration of dopamine and epinephrine).
[0050] It can be calculated that the detection limits of dopamine and epinephrine are 2.14 μmol / L and 1.94 μmol / L, respectively (S / N=3).
[0051] c) Anti-interference ability when detecting dopamine and adrenaline:
[0052] Ascorbic acid and uric acid are common endogenous substances found in serum and are present in large quantities. Their structures are similar to those of dopamine and epinephrine, resulting in similar or even overlapping oxidation peak potentials. Therefore, the detection of dopamine and epinephrine using electrochemical voltammetry may be affected by ascorbic acid and uric acid. Therefore, it is necessary to investigate the effect of excess ascorbic acid or uric acid on the results of dopamine and epinephrine detection using square wave cyclic voltammetry.
[0053] The testing process is as follows:
[0054] 1) Prepare a dopamine-epinephrine standard solution with a dopamine concentration of 0.05 mol / L and an epinephrine concentration of 0.05 mol / L. Then, take 35 μL of the dopamine-epinephrine standard solution and mix it with 25 mL of a 0.1 mol / L, pH 7.0, sodium dihydrogen phosphate-sodium dihydrogen phosphate buffer solution. Vortex for 90 s to obtain a mixed solution C with a dopamine concentration of 70 μmol / L and an epinephrine concentration of 70 μmol / L (denoted as 70 μM DA + 70 μM EP).
[0055] 2) preparing a 0.5 mol / L ascorbic acid solution and a 0.5 mol / L uric acid solution, and then taking 17.5 μL of the ascorbic acid solution and the uric acid solution and mixing them with the mixed solution C in step 1), respectively, and vortexing for 90 s to obtain a mixed solution D with a dopamine concentration of 70 μmol / L, an epinephrine concentration of 70 μmol / L, and an ascorbic acid concentration of 350 μmol / L (denoted as 70 μM DA + 70 μM EP + 350 μM AA) and a mixed solution E with a dopamine concentration of 70 μmol / L, an epinephrine concentration of 70 μmol / L, and a uric acid concentration of 350 μmol / L (denoted as 70 μM DA + 70 μM EP + 350 μM UA);
[0056] 3) Take 50 μL of mixed solutions C to E and perform square wave cyclic voltammetry detection using a three-electrode system (working electrode: graphene electrode, reference electrode: Ag / AgCl electrode, counter electrode: graphite electrode). The applied voltage scan range is -0.5 V to 0.3 V, the pulse amplitude is 50 mV, the square wave frequency is 15 Hz, the potential increment is 4 mV, and three parallel tests are set. The square wave cyclic voltammetry curves of dopamine-epinephrine under the interference of ascorbic acid are shown as follows: Figure 5 As shown in the figure, the square wave cyclic voltammetry curve of dopamine-epinephrine under the interference of uric acid is as follows: Figure 6 shown.
[0057] Depend on Figure 5 It can be seen that when the concentration of ascorbic acid in the mixed solution is 350 μmol / L, an oxidation peak of ascorbic acid appears at -0.11 V during the forward scan, while no obvious reduction peak appears during the reverse scan.
[0058] Depend on Figure 6 It can be seen that when the concentration of uric acid in the mixed solution is 350 μmol / L, no additional redox peak appears.
[0059] It can be seen that when dopamine and epinephrine are detected simultaneously using square wave cyclic voltammetry, neither ascorbic acid nor uric acid interferes with the detection of dopamine and epinephrine.
[0060] d) Recovery rates of dopamine and epinephrine during the assay:
[0061] The testing process is as follows:
[0062] 1) Add 2.5 mL of calf serum to 22.5 mL of 0.1 mol / L, pH 7.0, disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution, then add 10 μL of 0.05 mol / L dopamine standard solution, 10 μL of 0.05 mol / L epinephrine standard solution, or 10 μL of 0.05 mol / L dopamine-epinephrine standard solution. Vortex for 90 s to obtain calf serum spiked sample mixture A with a dopamine concentration of 20 μmol / L, calf serum spiked sample mixture B with an epinephrine concentration of 20 μmol / L, and calf serum spiked sample mixture C with both dopamine and epinephrine concentrations of 20 μmol / L.
[0063] 2) 50 μL of calf serum spiked sample mixtures A–C were subjected to square wave cyclic voltammetry using a three-electrode system (graphene working electrode, Ag / AgCl reference electrode, and graphite counter electrode). The applied voltage sweep range was -0.5 V to 0.3 V, the pulse amplitude was 50 mV, the square wave frequency was 15 Hz, and the potential increment was 4 mV. Three parallel experiments were performed, and the peak-to-peak reduction current was recorded.
[0064] 3) Add 10 μL of a 0.05 mol / L dopamine standard solution to the calf serum spiked sample mixture A, add 10 μL of a 0.05 mol / L epinephrine standard solution to the calf serum spiked sample mixture B, and add 10 μL of a 0.05 mol / L dopamine-epinephrine standard solution to the calf serum spiked sample mixture C. Vortex for 90 s and perform square wave cyclic voltammetry with a three-electrode system. Set up three parallel experiments, record the reduction peak current value, and repeat the above operation four times;
[0065] 4) Performing a linear fit between the positive reduction peak current obtained in step 3) and the dopamine concentration, and obtaining the dopamine concentration from the positive potential reduction peak; performing a linear fit between the negative reduction peak current obtained in step 3) and the sum of the dopamine and epinephrine concentrations, and obtaining the sum of the two substance concentrations from the negative potential reduction peak, and subtracting the dopamine concentration obtained from the positive potential reduction peak to obtain the epinephrine concentration. Then, calculating the recoveries of dopamine and epinephrine detected separately and simultaneously. The test results are shown in the following table:
[0066] Table 1 Recovery rates of dopamine and epinephrine detected separately and simultaneously
[0067]
[0068] As shown in Table 1, the recoveries of dopamine and epinephrine when detected separately were 100.05% and 107.15%, respectively, with relative standard deviations of ≤6.43%. When dopamine and epinephrine were detected simultaneously, the recoveries were 108.25% and 107.01%, respectively, with relative standard deviations of ≤4.59%, indicating that the method of the present invention has a good recovery rate.
[0069] In summary, the method for simultaneous detection of dopamine and epinephrine of the present invention has the following advantages:
[0070] 1) Simultaneous detection of dopamine and epinephrine can be achieved on bare electrodes with high sensitivity;
[0071] 2) When performing simultaneous detection of dopamine and epinephrine, it has strong anti-interference ability against coexisting substances in the body;
[0072] 3) The ability to simultaneously measure dopamine and adrenaline concentrations in biological samples helps to understand the impact and pathogenesis of abnormal dopamine and adrenaline levels on biological diseases.
[0073] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.
Claims
1. A method for simultaneously detecting dopamine and epinephrine, characterized in that: The following steps are involved: 1) Prepare a series of dopamine standard solutions at different concentrations, mix them with buffer solutions, and perform square wave cyclic voltammetry. Based on the positive reduction peak current obtained, draw a standard curve of positive reduction peak current versus dopamine concentration. Prepare a series of dopamine and epinephrine standard solutions at different concentrations, mix them with buffer solutions, and perform square wave cyclic voltammetry. Based on the negative reduction peak current obtained, draw a standard curve of negative reduction peak current versus total dopamine and epinephrine concentration. 2) Mixing the sample solution with the buffer solution and performing square wave cyclic voltammetry to measure the positive reduction peak current and the negative reduction peak current. The dopamine concentration is then determined by referring to a standard curve of positive reduction peak current versus dopamine concentration. The total dopamine and epinephrine concentrations are then determined by referring to a standard curve of negative reduction peak current versus total dopamine and epinephrine concentrations. The epinephrine concentration is then determined by subtracting the dopamine concentration from the total dopamine and epinephrine concentration. The three-electrode system used in the square wave cyclic voltammetry detection is a graphene electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a graphite electrode as the counter electrode; The voltage range of the square wave cyclic voltammetry detection is -0.5V to 0.3V, the pulse amplitude is 20mV to 80mV, the square wave frequency is 5Hz to 30Hz, and the potential increment is 1mV to 10mV.
2. The method according to claim 1, wherein: The buffer solution is one of acetic acid-sodium acetate buffer solution, citric acid-sodium citrate buffer solution, boric acid-sodium borate buffer solution, sodium carbonate-sodium bicarbonate buffer solution, disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution, and disodium hydrogen phosphate-potassium dihydrogen phosphate buffer solution.
3. The method according to claim 2, wherein: The buffer solution is a disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution.
4. The method according to claim 3, wherein: The concentration of the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution is 0.005 mol / L to 3 mol / L.
5. The method according to claim 3 or 4, characterized in that: The pH value of the disodium hydrogen phosphate-sodium dihydrogen phosphate buffer solution is 5-9.
6. The method according to claim 1, wherein: The dopamine and epinephrine concentrations in the dopamine-epinephrine standard solution are the same; and the voltammetry detection is performed with at least three parallel tests.