Photoelectrochemical sensor, preparation method and application

Abstract

The application provides a photoelectrochemical sensor, a preparation method and application. The photoelectrochemical sensor is obtained by electropolymerizing a molecularly imprinted polymer on a BiVO4 / CuO-FTO electrode on the basis of the BiVO4 / CuO-FTO electrode, pyrrole as a functional monomer and terramycin as a template molecule. A three-electrode system is constructed by using the photoelectrochemical sensor, terramycin and a buffer solution are mixed to form a standard mixed solution containing different terramycin concentrations, and a photocurrent test is performed to obtain standard photocurrent signals of different terramycin concentrations. A standard curve is obtained by plotting terramycin concentrations as abscissa and the standard photocurrent signals as ordinate. A milk sample containing terramycin is subjected to the above photocurrent test operation to obtain a photocurrent signal, and the terramycin content in the sample solution is obtained by substituting the photocurrent signal into the standard curve. The application has the advantages of small size, simple operation, simple preparation, low cost, good specific selectivity and great application prospect.

Description

Technical Field

[0001] This invention relates to the field of analytical detection, and in particular to a photoelectrochemical sensor, its preparation method, and its application. Background Technology

[0002] Milk has become an important part of people's daily diet. The protein in milk helps strengthen muscles and aids in recovery, contributing to overall health. Oxytetracycline, a first-generation natural tetracycline antibiotic, has good inhibitory effects on both Gram-negative and Gram-positive bacteria, thus holding significant clinical value in livestock and poultry farming. Oxytetracycline is also widely used in cattle farms to treat diseases in beef and dairy cattle. Studies have shown that oxytetracycline has a long elimination time in animals and readily binds to proteins and other nutrients in milk. Therefore, after the use of this drug, its residues may enter the milk along with the milk, potentially affecting not only milk quality but also human health. To ensure milk safety, various countries have set maximum residue limits for oxytetracycline in milk. Therefore, research on analytical methods for oxytetracycline residues in milk is particularly important. Accurate and reliable analytical methods can promptly detect and control oxytetracycline residues in milk, ensuring milk quality and consumer health.

[0003] Although various methods for detecting oxytetracycline have been developed, such as gas chromatography-mass spectrometry (GC-MS), thin-layer chromatography (TLC), high-performance liquid chromatography-mass spectrometry (HPLC-MS), and enzyme-linked immunosorbent assay (ELISA), these methods all have some drawbacks, such as expensive equipment, complex operation, and cumbersome pretreatment. Given the potential harm to human health from oxytetracycline residues in milk, it is necessary to develop a simple, accurate, rapid, and low-cost detection method. Photoelectrochemical sensors have attracted considerable attention due to their advantages over traditional electrochemical sensors, including low background current, simple instrumentation, low cost, ease of operation, and high sensitivity.

[0004] However, photoelectric sensors also have drawbacks such as poor anti-interference ability and low specificity in identifying target objects. Traditional molecular imprinted sensors, on the other hand, have the advantages of high specificity and good stability, but they also suffer from poor sensitivity. Summary of the Invention

[0005] In view of the above, the main objective of this invention is to provide a photoelectrochemical sensor, its preparation method, and its application to solve the aforementioned technical problems.

[0006] This invention provides a method for preparing a photoelectrochemical sensor. The method is used to prepare the aforementioned photoelectrochemical sensor and includes the following steps:

[0007] BiVO 4 / An insulating layer is applied to the unmodified portion of the conductive surface of the CuO-FTO electrode to obtain a BiVO4 / CuO-FTO working electrode.

[0008] Oxytetracycline and pyrrole functional monomers were electropolymerized onto the BiVO4 / CuO-FTO working electrode to obtain the MIP-BiVO4 / CuO-FTO electrode.

[0009] MIP-BiVO 4 / Oxytetracycline was eluted from the CuO-FTO electrode to obtain a photoelectrochemical sensor.

[0010] This invention also provides a photoelectrochemical sensor, which is obtained by electropolymerizing a molecularly imprinted polymer on a BiVO4 / CuO-FTO electrode using pyrrole as a functional monomer and oxytetracycline as a template molecule. This invention also provides an application of the photoelectrochemical sensor, wherein the photoelectrochemical sensor prepared using the above-described method is used for the detection of oxytetracycline content in milk.

[0011] This invention also provides a method for detecting oxytetracycline content in milk based on a photoelectrochemical sensor, the method specifically comprising the following steps:

[0012] Based on a three-electrode system, the photoelectrochemical sensor is used as the working electrode, the Ag / AgCl electrode is used as the reference electrode, and the platinum wire is used as the counter electrode;

[0013] A standard mixture of oxytetracycline and Na2EDTA buffer solution was used as the electrolyte.

[0014] The photocurrent of the electrolyte was tested, and the photocurrent measured with an electrolyte without oxytetracycline was used as a comparison. The difference between the two was used as the standard photoelectric signal.

[0015] The photocurrent test was repeated by changing the concentration of oxytetracycline in the electrolyte, and the results of each test were compared with the photocurrent measured with an electrolyte without oxytetracycline to obtain standard photoelectric signals with different concentrations of oxytetracycline.

[0016] A standard curve was obtained by plotting oxytetracycline concentration on the x-axis and standard photoelectric signal on the y-axis.

[0017] The milk sample solution containing oxytetracycline was mixed with Na2EDTA buffer to form an electrolyte and a photocurrent test was performed to obtain a photoelectric signal. The photoelectric signal was then substituted into a standard curve to obtain the oxytetracycline content in the sample solution.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. The method provided by the present invention has good specificity and selectivity for the detection of oxytetracycline;

[0020] 2. The method provided by the present invention is simple to operate, easy to prepare, low in cost, and does not require operation by specific professionals, and has great application prospects in the field of rapid on-site detection.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments of the invention. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the construction method of the photoelectrochemical molecularly imprinted sensor of the present invention;

[0023] Figure 2 The photoelectrochemical sensor constructed in Example 2 of this invention shows the change in photocurrent after being placed for 7 days.

[0024] Figure 3 Photoelectric signals corresponding to different oxytetracycline concentrations in Example 5 of this invention (ai: 0.1, 1, 10, 100, 1000 nmol / L).

[0025] Figure 4 This is a standard curve of the relationship between the logarithm of oxytetracycline concentration and photoelectric signal in Example 5 of the present invention (oxytetracycline concentration in the range of 0.1-1000 nmol / L).

[0026] Figure 5 The photoelectric signals corresponding to different oxytetracycline concentrations (0.01, 0.1, 1, 10, 100, 1000 nmol / L) in Example 6 of the present invention are shown.

[0027] Figure 6 This is a standard curve of the relationship between the logarithm of oxytetracycline concentration and photoelectric signal in Example 6 of the present invention (oxytetracycline concentration in the range of 0.01-1000 nmol / L).

[0028] Figure 7 This is a standard curve of the relationship between the logarithm of oxytetracycline concentration and photoelectric signal in Example 7 of the present invention (oxytetracycline concentration in the range of 0.02-5 mmol / L).

[0029] Figure 8 The photoelectrochemical sensor of Example 4 of the present invention responds to photoelectric signals of oxytetracycline, chloramphenicol, erythromycin, and tetracycline hydrochloride. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] These and other aspects of the embodiments of the present invention will become clear from the following description and accompanying drawings. In these descriptions and drawings, some specific embodiments of the present invention are specifically disclosed to illustrate some ways of implementing the principles of the embodiments of the present invention; however, it should be understood that the scope of the embodiments of the present invention is not limited thereto.

[0032] Example 1

[0033] This embodiment discloses a photoelectrochemical sensor, which is obtained by electropolymerizing a molecularly imprinted polymer on a BiVO4 / CuO-FTO electrode, using pyrrole as a functional monomer and oxytetracycline as a template molecule.

[0034] Example 2

[0035] Please see Figure 1 This embodiment discloses a method for preparing a photoelectrochemical sensor, the method comprising the following steps:

[0036] Step 1: Grind BiVO4 / CuO into a fine powder. Take 40 mg of the ground BiVO4 / CuO, add 2 mL of isopropanol, and then add 40 μL of Nafion D-521 solution to a centrifuge tube. Sonicate for 20 min.

[0037] The mixture was placed in a centrifuge tube and shaken to mix. FTO glass was taped to cover its surface down to a remaining 1 cm × 1 cm area, and then placed in the centrifuge tube for four centrifugation cycles to deposit BiVO4 / CuO onto the FTO. After drying, the unmodified conductive surface (excluding the 1 cm × 1 cm area) was covered with an insulating layer (in this embodiment, nail polish was used as the insulating layer). After air drying, the BiVO4 / CuO-FTO working electrode was obtained.

[0038] Using pyrrole (OPD) as the functional monomer and oxytetracycline (OTC) as the template molecule, a molecularly imprinted polymer was electropolymerized on a BiVO4 / CuO-FTO electrode. The polymerization reaction was carried out by cyclic voltammetry (CV) in an acetate buffer solution at pH 7 containing 0.6 mM pyrrole and 0.2 mM OTC, with a voltage range of 0.6 V, a scan rate of 50 mV / s, and 30 cycles. The electrode was then slowly rinsed with distilled water and air-dried to obtain the MIP-BiVO4 / CuO-FTO electrode.

[0039] The prepared MIP-BiVO4 / CuO-FTO was placed in 0.2 mol / L PBS buffer solution (pH=7.4), and a constant voltage of +0.9 V was set. After elution for 10 min, it was repeatedly washed with deionized water to obtain the photoelectrochemical sensor, denoted as rMIP-BiVO4 / CuO-FTO electrode.

[0040] Example 3

[0041] This embodiment discloses a method for preparing a photoelectrochemical sensor, the method comprising the following steps:

[0042] Step 1: Grind BiVO4 / CuO into a fine powder. Take 50 mg of the ground BiVO4 / CuO, add 2 mL of isopropanol, and then add 45 μL of Nafion D-521 solution to a centrifuge tube. Sonicate for 20 min.

[0043] The mixture was placed in a centrifuge tube and shaken to mix. FTO glass was taped to cover its surface down to a remaining 1 cm × 1 cm area, and then placed in the centrifuge tube for five centrifugation cycles to deposit BiVO4 / CuO onto the FTO. After drying, the unmodified conductive surface (excluding the 1 cm × 1 cm area) was covered with an insulating layer (in this embodiment, nail polish was used as the insulating layer). After air drying, the BiVO4 / CuO-FTO working electrode was obtained.

[0044] Using pyrrole as the functional monomer and oxytetracycline as the template molecule, a molecularly imprinted polymer was electropolymerized on a BiVO4 / CuO-FTO electrode. The polymerization reaction was carried out by cyclic voltammetry in a pH 7 acetate buffer containing 0.7 mM pyrrole and 0.3 mM OTC, with a voltage range of 0.8 V, a scan rate of 50 mV / s, and 40 cycles. The electrode was then slowly rinsed with distilled water and air-dried to obtain the MIP-BiVO4 / CuO-FTO electrode.

[0045] The prepared MIP-BiVO4 / CuO-FTO was placed in 0.2 mol / L PBS buffer solution (pH=7.4), and a constant voltage of +0.9 V was set. After elution for 10 min, it was repeatedly washed with deionized water to obtain the photoelectrochemical sensor, denoted as rMIP-BiVO4 / CuO-FTO electrode.

[0046] Example 4

[0047] This embodiment discloses a method for preparing a photoelectrochemical sensor, the method comprising the following steps:

[0048] Step 1: Grind BiVO4 / CuO into a fine powder. Take 20 mg of the ground BiVO4 / CuO, add 2 mL of isopropanol, and then add 40 μL of Nafion D-521 solution to a centrifuge tube. Sonicate for 20 min.

[0049] The mixture was placed in a centrifuge tube and shaken to mix. FTO glass was taped to cover its surface down to a remaining 1 cm × 1 cm area, and then placed in the centrifuge tube for four centrifugation cycles to deposit BiVO4 / CuO onto the FTO. After drying, the unmodified conductive surface (excluding the 1 cm × 1 cm area) was covered with an insulating layer (in this embodiment, nail polish was used as the insulating layer). After air drying, the BiVO4 / CuO-FTO working electrode was obtained.

[0050] Using pyrrole as the functional monomer and oxytetracycline as the template molecule, a molecularly imprinted polymer was electropolymerized on a BiVO4 / CuO-FTO electrode. The polymerization reaction was carried out by cyclic voltammetry in an acetate buffer solution containing 0.3 mM pyrrole and 0.1 mM oxytetracycline at pH 7, with a voltage range of 0.2 V, a scan rate of 50 mV / s, and 15 cycles. The electrode was then slowly rinsed with distilled water and air-dried to obtain the MIP-BiVO4 / CuO-FTO electrode.

[0051] The prepared MIP-BiVO4 / CuO-FTO was placed in 0.2 mol / L PBS buffer solution (pH=7.4), and a constant voltage of +0.9 V was set. After elution for 10 min, it was repeatedly washed with deionized water to obtain the photoelectrochemical sensor, denoted as rMIP-BiVO4 / CuO-FTO electrode.

[0052] Example 5

[0053] This embodiment discloses an application of a photoelectrochemical sensor. The photoelectrochemical sensor prepared using the above-described method is used to detect the oxytetracycline content in milk. The method for detecting the oxytetracycline content in milk using the photoelectrochemical sensor specifically includes the following steps:

[0054] Step 1: A typical three-electrode system was adopted, with an Ag / AgCl electrode used as the reference electrode, a platinum wire as the counter electrode, and the rMIP-BiVO4 / CuO-FTO electrode prepared in Example 2 as the working electrode. A 70 W metal halide lamp was used as the light source to irradiate the three-electrode system. The photocurrent was measured by alternating cycles of 20 s light exposure and 20 s darkness. After the sensor was prepared and stored for seven days, the photocurrent response was measured by turning the lamp on and off every 20 s for 1000 s. Figure 2 It can be observed that the sensor has high stability.

[0055] Step 2: Using a standard mixture of 2 mL of oxytetracycline aqueous solution and 8 mL of Na2EDTA buffer as the electrolyte, the photocurrent was measured. The photocurrent measured with an electrolyte without oxytetracycline was used as a comparison, and the difference between the two was taken as the photoelectric signal (ΔI).

[0056] Step 3: Change the concentration of oxytetracycline in the electrolyte to 0.1, 1, 10, 100, and 1000 nmol / L. Repeat step 1 and test the results as follows. Figure 3 The photoelectric signals of the sensor for standard solutions of oxytetracycline at different concentrations;

[0057] Step 4: Plot a graph with oxytetracycline concentration on the x-axis and photoelectric signal on the y-axis to obtain the following result. Figure 4 The standard curve shown has ΔI = 0.85687logC + 1.1669 (nmol / L), and the corresponding correlation coefficient (R²) is... 2 The value is 0.99022;

[0058] Step 5: Take 2 mL of milk sample obtained from the local market and place it in a beaker. Add 8 mL of Na2EDTA buffer and sonicate to mix. Centrifuge the mixture twice at 4500 rpm for 15 min each time, and filter it three times using a 0.45 μm ultrafiltration membrane. Add 0.20 mmol / L oxytetracycline to the filtrate and repeat the test in Step 1. The measured photoelectric signal is used to calculate the oxytetracycline concentration as 0.21, with a recovery rate of 105%.

[0059] Example 6

[0060] This embodiment discloses an application of a photoelectrochemical sensor. The photoelectrochemical sensor, prepared using the method described above, is used to detect the oxytetracycline content in milk. The method for detecting the oxytetracycline content in milk using the photoelectrochemical sensor specifically includes the following steps:

[0061] Step 1: A typical three-electrode system was used, with an Ag / AgCl electrode as the reference electrode, a platinum wire as the counter electrode, and the rMIP-BiVO4 / CuO-FTO electrode prepared in Example 3 as the working electrode. A 70 W metal halide lamp was used as the light source to illuminate the three-electrode system. The photocurrent was measured by alternating cycles of 20 s illumination and 20 s darkness.

[0062] Step 2: Using a standard mixture of 3 mL of oxytetracycline aqueous solution and 7 mL of Na2EDTA buffer as the electrolyte, the photocurrent was measured. The photocurrent measured with an electrolyte without oxytetracycline was used as a comparison, and the difference between the two was taken as the photoelectric signal (ΔI).

[0063] Step 3: Change the concentration of oxytetracycline in the electrolyte to 0.01, 0.1, 1, 10, 100, and 1000 nmol / L. Repeat step 3 and test the results as follows. Figure 5 The photoelectric signals of the sensor for standard solutions of oxytetracycline at different concentrations;

[0064] Step 4: Plot a graph with oxytetracycline concentration on the x-axis and photoelectric signal on the y-axis to obtain the following result. Figure 6 The standard curve shown (ΔI=1.22512logC+3.64641, correlation coefficient R) 2 =0.9909);

[0065] Step 5: Take 3 mL of milk sample obtained from the local market and place it in a beaker. Add 7 mL of Na2EDTA buffer and sonicate to mix. Centrifuge the mixture twice at 4500 rpm for 15 min each time, and filter it three times using a 0.45 μm ultrafiltration membrane. Add 0.50 mmol / L oxytetracycline to the filtrate and repeat step 3. The measured photoelectric signal is used to calculate the oxytetracycline concentration as 0.49, with a recovery rate of 98%.

[0066] Example 7

[0067] This embodiment discloses an application of a photoelectrochemical sensor. The photoelectrochemical sensor, prepared using the method described above, is used to detect the oxytetracycline content in milk. The method for detecting the oxytetracycline content in milk using the photoelectrochemical sensor specifically includes the following steps:

[0068] Step 1: A typical three-electrode system was used, with an Ag / AgCl electrode as the reference electrode, a platinum wire as the counter electrode, and the rMIP-BiVO4 / CuO-FTO electrode prepared in Example 4 as the working electrode. A 70 W metal halide lamp was used as the light source to illuminate the three-electrode system. The photocurrent was measured by alternating cycles of 20 s illumination and 20 s darkness.

[0069] Step 2: Using a standard mixture of 1 mL oxytetracycline aqueous solution and 9 mL Na2EDTA buffer as the electrolyte, the photocurrent was measured. The photocurrent measured with an electrolyte without oxytetracycline was used as a comparison, and the difference between the two was taken as the photoelectric signal (ΔI).

[0070] Step 3: Change the concentration of oxytetracycline in the electrolyte to 0.02, 0.04, 0.10, 0.6, 1, and 5 mmol / L respectively. Repeat step 1 and test the photoelectric signal of the sensor for standard solutions of oxytetracycline at different concentrations.

[0071] Step 4: Plot a graph with oxytetracycline concentration on the x-axis and photoelectric signal on the y-axis to obtain the following result. Figure 7 The standard curve shown (ΔI=0.65353 logC +1.1042, R) 2 =0.99394);

[0072] Step 5: Take 1 mL of milk sample obtained from the local market and place it in a beaker. Add 9 mL of Na2EDTA buffer and mix by sonication. Centrifuge the mixture twice at 4500 rpm for 15 min each time, and filter it three times using a 0.45 μm ultrafiltration membrane. Add 1 mmol / L oxytetracycline to the filtrate and repeat the test in Step 1. The measured photoelectric signal was used to calculate the oxytetracycline concentration as 0.97, with a recovery rate of 97%. To examine the specific recognition ability of the constructed sensor for oxytetracycline, the photoelectric signals of four milk samples containing the same concentration (0.6 mmol / L) of oxytetracycline, tetracycline hydrochloride, erythromycin, and chloramphenicol were measured using the same assay procedure. Figure 8 As shown, the constructed photoelectrochemical molecular imprinted sensor has a good recognition ability for oxytetracycline.

[0073] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0074] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0075] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method of preparing a photoelectrochemical sensor, characterized by, The method comprises the following steps: An insulating layer is coated on the non-modified part of the conductive surface of the BiVO4 / CuO-FTO electrode to obtain a BiVO4 / CuO-FTO working electrode; An MIP-BiVO4 / CuO-FTO electrode is obtained by using an electropolymerization method to electropolymerize terramycin and a pyrrole functional monomer onto the BiVO4 / CuO-FTO working electrode. The method for obtaining the MIP-BiVO4 / CuO-FTO electrode by using the electropolymerization method to electropolymerize terramycin and a pyrrole functional monomer onto the BiVO4 / CuO-FTO working electrode specifically comprises the following steps: The MIP-BiVO4 / CuO-FTO electrode is placed in an acetate buffer solution containing 0.3-0.6 mM of pyrrole and 0.1-0.2 mM of terramycin with a pH of 7, a voltage range of 0.2-0.6 V, a scanning speed of 50 mv / s, and a cycle number of 15-30 times, and then the MIP-BiVO4 / CuO-FTO electrode is slowly rinsed with distilled water and dried to obtain the MIP-BiVO4 / CuO-FTO electrode. The terramycin in the MIP-BiVO4 / CuO-FTO electrode is eluted to obtain a photoelectrochemical sensor. The method for eluting the terramycin in the MIP-BiVO4 / CuO-FTO electrode to obtain the photoelectrochemical sensor specifically comprises the following steps: The prepared MIP-BiVO4 / CuO-FTO is placed in a 0.2 mol / L PBS buffer solution with a pH of 7.4, a constant voltage of +0.9 V is set, elution is performed for 10 min, and then the photoelectrochemical sensor is obtained by repeatedly washing with deionized water.

2. The method of claim 1, wherein the photoelectrochemical sensor is prepared by the steps of: The method for preparing the BiVO4 / CuO-FTO electrode specifically comprises the following steps: The BiVO4 / CuO is ground into fine powder, mixed with isopropyl alcohol and a Nafion D-521 solution, and then the mixture is deposited onto an FTO conductive glass sheet by centrifugation to form the BiVO4 / CuO-FTO electrode.

3. An electrochemical sensor, comprising: The photoelectrochemical sensor is prepared by the method for preparing a photoelectrochemical sensor according to any one of claims 1 to 2, and the photoelectrochemical sensor is obtained by electropolymerizing a molecularly imprinted polymer on the BiVO4 / CuO-FTO electrode using pyrrole as a functional monomer and terramycin as a template molecule.

4. An application of a photoelectrochemical sensor, the photoelectrochemical sensor is prepared by the method for preparing a photoelectrochemical sensor according to any one of claims 1 to 2, and the photoelectrochemical sensor is used for detecting the content of terramycin in milk, and the method for detecting the content of terramycin in milk by using the photoelectrochemical sensor specifically comprises the following steps: Based on a three-electrode system, the photoelectrochemical sensor is used as a working electrode, an Ag / AgCl electrode is used as a reference electrode, and a platinum wire is used as a counter electrode; A standard mixture of terramycin and Na2EDTA buffer solution is used as an electrolyte. The electrolyte is subjected to photoelectric current test, and the photoelectric current of the electrolyte without terramycin is taken as a comparison, and the difference between the two is taken as a standard photoelectric signal; The photoelectric current test is repeated by changing the concentration of terramycin in the electrolyte, and the test result of each time is compared with the photoelectric current of the electrolyte without terramycin, and the standard photoelectric signal of different terramycin concentrations is obtained; The terramycin concentration is taken as the horizontal coordinate, and the standard photoelectric signal is taken as the vertical coordinate to draw a standard curve; The milk sample solution containing terramycin to be tested is mixed with Na2EDTA buffer to form an electrolyte, and subjected to photoelectric current test to obtain a photoelectric signal, and the photoelectric signal is substituted into the standard curve to obtain the terramycin content in the sample solution to be tested.

5. Use of a photoelectrochemical sensor according to claim 4, characterized in that, In the photoelectric current test, a 70 W halogen lamp is used as a light source to irradiate three electrodes, and the test is carried out under the condition of no bias voltage, and every 20 s of irradiation is followed by 20 s of light shielding.

6. Use of a photoelectrochemical sensor according to claim 5, characterized in that, The milk sample solution containing terramycin to be tested is a milk sample obtained from the market, Na2EDTA buffer is added, ultrasonic mixing is carried out, centrifugation is carried out to obtain supernatant, and then 0.45 μm ultrafiltration membrane is used for filtration three times, and finally different concentrations of standard terramycin samples are added.

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