Ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on surface of fresh meat

Abstract

The invention discloses an aggregation-induced emission enhancement-based ratiometric fluorescence analysis method for sodium tetraborate on the surface of fresh meat. The ratiometric fluorescence analysis method comprises the following steps: step 1, preparing a multifunctional ratiometric fluorescence probe TPQDs; 2, exploring the sensitivity, selectivity, anti-interference capability and stability of a ratio fluorescence analysis method; and 3, evaluating the application effect of the ratio fluorescence analysis method. The invention provides a ratio fluorescence analysis method for detecting borax on the surface of fresh meat for the first time; the ratio fluorescence analysis method comprises two fluorescence emissions, namely reference emission and response emission, so that the anti-interference capability of the method can be remarkably improved; the defects of expensive equipment, complex operation and inapplicability to field analysis are overcome; the method is high in detection sensitivity which can reach 4.77 mu g / L, and can meet the detection of trace borax on the surface of meat; the ratio fluorescence analysis method has good selectivity and anti-interference capability.

Description

Technical Field

[0001] The present invention relates to the technical field of detection methods for trace carcinogens in food safety, and particularly to a ratiometric fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat. Background Art

[0002] Sodium tetraborate, also known as borax (sodium tetraborate, borax), is a typical inorganic chemical with hygroscopicity and antibacterial activity, and is widely used as a household cleaner, insecticide, disinfectant and desiccant. In addition, borax can be used to improve the appearance or taste of food (especially fresh food), but it has potential carcinogenic threats to the stomach, kidneys, lungs and brain and has attracted attention in the field of food safety. However, some vendors illegally use borax to keep fresh meat in good appearance and taste, leading to a series of food safety problems. In particular, the Chinese food culture makes people prefer fresh ingredients, and the exposure risk of borax may be more serious. Therefore, it is quite important to establish an analytical method for rapid on-site detection of borax.

[0003] At present, the detection methods for borax include curcumin-based colorimetry, electronic nose-based sensor array method and biosensor-based method. The above methods all have certain problems more or less, such as expensive equipment, complex operation, poor anti-interference ability or inapplicability to rapid on-site analysis, etc. Although there has been fluorescence sensing for borax, there is no ratiometric fluorescence analysis method for borax detection, nor is there a ratiometric fluorescence analysis method based on the aggregation-induced emission (AIE) effect for borax. Summary of the Invention

[0004] The purpose of the present invention is to provide a ratiometric fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A ratiometric fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat, the ratiometric fluorescence analysis method comprising the following steps:

[0006] Step 1. Preparation of the multifunctional ratiometric fluorescence probe TPQDs;

[0007] Step 2. Exploration of the sensitivity, selectivity, anti-interference ability and stability of the ratiometric fluorescence analysis method;

[0008] Step 3. Evaluation of the application effect of the ratiometric fluorescence analysis method;

[0009] The preparation of the multifunctional ratiometric fluorescence probe TPQDs first synthesizes manganese-doped zinc sulfide quantum dots Mn-ZnSQDs by chemical precipitation method;

[0010] The specific method for preparing the multifunctional ratio fluorescence probe TPQDs: Mix 60 μL of 30 g / L polyvinyl alcohol (PVA), 50 μL of QDs suspension, 20 μL of 10 g / L tetraphenylethylene (TPE), and 1820 μL of water to construct the probe TPQDs.

[0011] Preferably, the specific steps for synthesizing manganese-doped zinc sulfide quantum dots (Mn-ZnSQDs) by the chemical precipitation method are as follows:

[0012] Step 1. Under nitrogen protection, stir 10 mL of 2.5 mol / L zinc sulfate, 10 mL of 0.1 mol / L manganese chloride solution, and 20 mL of ultrapure water at room temperature for 5 minutes.

[0013] Step 2. Add 5 mL of 2.5 mol / L sodium sulfide solution dropwise to the mixture.

[0014] Step 3. After 2 hours, centrifuge and wash the above mixture 5 times with ethanol / water at V / V = 1:1 to obtain the product.

[0015] Step 4. Dry the final product in a vacuum oven at 100 °C.

[0016] Preferably, in the preparation of the multifunctional ratio fluorescence probe TPQDs, the reference emission comes from QDs (at 605 nm), and the responsive emission comes from TPE (around 445 nm); after adding borax, borax reacts with PVA, increasing the viscosity of the system; as the viscosity increases, the intramolecular motion of TPE is restricted, enhancing the emission of TPE, i.e., the AIE effect; by comparing the ratio I 605 / I 445 change, the concentration of borax can be determined.

[0017] Preferably, for the sensitivity exploration of the ratio fluorescence analysis method: Add 50 μL of borax solutions with different concentrations of 0, 0.2, 0.8, 6, 8, 12, 20, 40, 400, and 1200 mg / L to TPQDs; the actual concentrations of borax in the mixture are 0, 5, 20, 150, 200, 300, 500, 1000, 10000, and 30000 μg / L respectively; then, immediately transfer the mixture to a 60 °C water bath and keep it for 18 minutes; finally, record the fluorescence spectra of the mixture at an excitation wavelength of 300 nm; in addition, using the visual fluorescence method, explore the sensitivity of TPQDs in 50 μL of borax solutions with different concentrations of 1200, 400, 40, 20, 12, 8, 6, and 0 mg / L respectively, and the actual concentrations of borax are 30000, 10000, 1000, 500, 300, 200, 150, and 0 μg / L respectively.

[0018] Preferably, for the selectivity investigation of the ratiometric fluorescence analysis method: Select common preservatives such as acetic acid (AA), benzoic acid (BA), and lactic acid (LA), as well as main components or similar substances in meat, cholesterol (Ch), collagen polypeptide (CP), thiamine hydrochloride (TH), bovine serum albumin (BSA), and L-cysteine (LC) as interferents. Add 50 μL of the interferent and 40 mg / L borax solution to TPQDs respectively to discuss the selectivity of the method; then, drop 50 μL of 40 mg / L borax solution into the TPQDs solution containing different interferents to explore their anti-interference ability respectively.

[0019] Preferably, for the stability investigation of the ratiometric fluorescence analysis method: The stability is mainly related to the modified quantum dots (QDs). The QDs are stored in a refrigerator at 2-6 °C, and the fluorescence spectra of the QDs are collected every five days for one month.

[0020] Preferably, for the evaluation of the application effect of the ratiometric fluorescence analysis method: For the fluorescence method, 40 μL of 1 g / L borax solution is evenly dropped onto the surface of 2 g of pork or chicken, with a contamination amount of 20 mg / kg. After the water evaporates, the contaminated meat is placed in a 50 mL centrifuge tube, and 20 mL of water is added. Then, after shaking for 5 minutes and removing the meat chunks, contaminated water containing some organic substances is obtained; after centrifuging at 4000 rpm for 5 minutes, small pieces of meat or meat grains are removed, 10 mL of the upper layer solution is added to 5 mL of n-hexane, and the mixture is shaken for 1 minute; after the mixture is layered, the water contaminated with borax is obtained from the supernatant; finally, the fluorescence spectrum of TPQDs containing 120 μL of contaminated water is collected, and the concentration of the contaminated water is calculated through the standard curve.

[0021] Preferably, for the evaluation of the application effect of the ratiometric fluorescence analysis method: For the visual fluorescence method, the "dropwise method" is used for borax sensing. 20 μL of 0, 40, 100, 200, 400, and 1000 mg / L borax solutions are respectively dropped onto the surface of the meat. The contaminated area of pork is 3.14 mm 2 , and the contaminated area of chicken is 4.91 mm 2 ; after the water evaporates, the TPQDs concentrated 5 times are dropped onto the same position; then, under 254 nm ultraviolet light, photos of the meat surface containing TPQDs and different concentrations of borax are recorded; in addition, the proposed ratiometric fluorescence method based on TPQDs is verified by inductively coupled plasma spectrometry (ICP-OES) method.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat. The present invention first proposes a ratio fluorescence analysis method for detecting borax on the surface of fresh meat. The ratio fluorescence analysis method itself includes two fluorescence emissions, namely reference emission and responsive emission. The former is used as an internal standard, which can significantly improve the anti-interference ability of the method. The fluorescence spectrometer involved in this method is a portable instrument, and the matching software can achieve "idiot-proof" operation, overcoming the disadvantages of expensive equipment, complex operation and inapplicability to on-site analysis in the existing methods. The detection sensitivity of this method can reach 4.77 μg / L, which can meet the detection of trace borax on the surface of meat.

[0024] 2. The ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat. The ratio fluorescence analysis method of the present invention has good selectivity and anti-interference ability; high sensitivity, which can meet the detection of trace borax; and the probe is stable within 25 days.

[0025] 3. The ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat. The present invention establishes a ratio fluorescence analysis method for borax. By mixing 60 μL of 30 g / L PVA, 50 μL of modified QDs suspension, 20 μL of 10 g / L TPE and 1820 μL of water, TPQDs are constructed. After adding borax, compared with the fluorescence emission of QDs (at about 605 nm), the fluorescence emission of TPE (around 445 nm) will gradually become stronger. The reason is that the addition of borax increases the viscosity, restricting the intramolecular motion of TPE, thereby enhancing the emission of TPE through the AIE effect. Furthermore, the detection of borax is realized by comparing the ratio change of the fluorescence intensities of QDs and TPE. Description of the Drawings

[0026] Figure 1 It is the flow chart of the ratio fluorescence analysis method of the present invention;

[0027] Figure 2 It is the flow chart of the chemical precipitation method for synthesizing manganese-doped zinc sulfide quantum dots Mn-ZnSQDs of the present invention;

[0028] Figure 3 It is the schematic diagram of the fluorescence method and visual fluorescence method based on TPQDs for borax detection of the present invention;

[0029] Figure 4 It is the result diagram of the selectivity (a) and anti-interference ability evaluation (b) of the ratio fluorescence analysis method of the present invention;

[0030] Figure 5Fluorescence spectra of TPQDs with different concentrations of borax added for the present invention (a) and relationship diagram of I605 / I445 vs. borax concentration C (b); the inset in b is the schematic diagram of the calibration curve of I605 / I445 vs. C in the range of 0 to 300 μg / L;

[0031] Figure 6 Schematic diagram of photos of TPQDs and different concentrations of borax under 254 nm ultraviolet light for the present invention (a) and relationship curve between 1000(IG / I) value and borax concentration (0 - 30000 μg / L) (b);

[0032] Figure 7 Schematic diagram of the preparation and application of the ratiometric fluorescence probe of TPQDs for the present invention. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0035] As Figures 1 to 7 shown, in this embodiment, a ratiometric fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat is provided. The ratiometric fluorescence analysis method includes the following steps:

[0036] Step 1. Preparation of the multifunctional ratiometric fluorescence probe TPQDs;

[0037] Step 2. Exploration of the sensitivity, selectivity, anti-interference ability and stability of the ratiometric fluorescence analysis method;

[0038] Step 3. Evaluation of the application effect of the ratiometric fluorescence analysis method;

[0039] The preparation of the multifunctional ratiometric fluorescence probe TPQDs first synthesizes manganese-doped zinc sulfide quantum dots Mn-ZnSQDs by chemical precipitation method;

[0040] The specific method for preparing the multifunctional ratio fluorescence probe TPQDs: Mix 60 μL of 30 g / L polyvinyl alcohol (PVA), 50 μL of QDs suspension, 20 μL of 10 g / L tetraphenylethylene (TPE), and 1820 μL of water to construct the probe TPQDs.

[0041] Specifically, the specific steps for synthesizing manganese-doped zinc sulfide quantum dots (Mn-ZnSQDs) by the chemical precipitation method are as follows:

[0042] Step 1. Under nitrogen protection, stir 10 mL of 2.5 mol / L zinc sulfate, 10 mL of 0.1 mol / L manganese chloride solution, and 20 mL of ultrapure water at room temperature for 5 minutes.

[0043] Step 2. Add 5 mL of 2.5 mol / L sodium sulfide solution dropwise to the mixture.

[0044] Step 3. After 2 hours, centrifuge and wash the above mixture 5 times with ethanol / water at V / V = 1:1 to obtain the product.

[0045] Step 4. Dry the final product in a vacuum oven at 100 °C.

[0046] Furthermore, in the preparation of the multifunctional ratio fluorescence probe TPQDs, the reference emission comes from QDs (at 605 nm), and the responsive emission comes from TPE (around 445 nm); after adding borax, borax reacts with PVA, increasing the viscosity of the system; as the viscosity increases, the intramolecular motion of TPE is restricted, enhancing the emission of TPE, i.e., the AIE effect; by comparing the ratio I 605 / I 445 change, the concentration of borax can be determined.

[0047] Furthermore, for the sensitivity exploration of the ratio fluorescence analysis method: Add 50 μL of borax solutions with different concentrations of 0, 0.2, 0.8, 6, 8, 12, 20, 40, 400, and 1200 mg / L to TPQDs; the actual concentrations of borax in the mixture are 0, 5, 20, 150, 200, 300, 500, 1000, 10000, and 30000 μg / L respectively; then, immediately transfer the mixture to a 60 °C water bath and keep it for 18 minutes; finally, record the fluorescence spectra of the mixture at an excitation wavelength of 300 nm; in addition, using the visual fluorescence method, explore the sensitivity of TPQDs in 50 μL of borax solutions with different concentrations of 1200, 400, 40, 20, 12, 8, 6, and 0 mg / L respectively, and the actual concentrations of borax are 30000, 10000, 1000, 500, 300, 200, 150, and 0 μg / L respectively.

[0048] Furthermore, the selectivity of the ratio fluorescence analysis method was investigated: common preservatives such as acetic acid (AA), benzoic acid (BA), and lactic acid (LA), as well as the main components or similar substances in meat, cholesterol (Ch), collagen polypeptide (CP), thiamine hydrochloride (TH), bovine serum albumin (BSA), and L-cysteine (LC) were selected as interferents. 50 μL of the interferent and 40 mg / L borax solution were respectively added to TPQDs to discuss the selectivity of the method; then, 50 μL of 40 mg / L borax solution was dropped into the TPQDs solution containing different interferents to explore their anti-interference ability respectively.

[0049] Furthermore, the stability of the ratio fluorescence analysis method was investigated: the stability is mainly related to the modified quantum dots (QDs). The QDs were stored in a refrigerator at 2 - 6 °C, and the fluorescence spectra of the QDs were collected every five days for one month.

[0050] Furthermore, for the evaluation of the application effect of the ratio fluorescence analysis method on the fluorescence method, 40 μL of 1 g / L borax solution was evenly dropped onto the surface of 2 g of pork or chicken with a contamination amount of 20 mg / kg. After the water evaporated, the contaminated meat was placed in a 50 mL centrifuge tube, and 20 mL of water was added. Then, after shaking for 5 minutes and removing the meat chunks, contaminated water containing some organic substances was obtained; after centrifuging at 4000 rpm for 5 minutes, small pieces of meat or meat particles were removed, 10 mL of the supernatant was added to 5 mL of n-hexane, and the mixture was shaken for 1 minute; after the mixture was layered, the water contaminated with borax was obtained from the supernatant; finally, the fluorescence spectrum of TPQDs containing 120 μL of contaminated water was collected, and the concentration of the contaminated water was calculated through the standard curve.

[0051] Furthermore, for the evaluation of the application effect of the ratio fluorescence analysis method on the visual fluorescence method, the "dropwise method" was used for borax sensing. 20 μL of 0, 40, 100, 200, 400, and 1000 mg / L borax solutions were respectively dropped onto the surface of the meat. The contaminated area of the pork was 3.14 mm 2 , and the contaminated area of the chicken was 4.91 mm 2 ; after the water evaporated, the TPQDs concentrated 5 times were dropped onto the same position; then, the photos of the meat surface containing TPQDs and different concentrations of borax were recorded under 254 nm ultraviolet light; in addition, the proposed ratio fluorescence method based on TPQDs was verified by inductively coupled plasma spectrometry (ICP-OES) method.

[0052] The ratio fluorescence analysis method has good selectivity and anti-interference ability.

[0053] As Figure 4, the spectra of the TPQDs probe solution containing different interferents (AA, BA, LA, Ch, CP, TH, BSA, and LC) showed a slight increase in fluorescence emission at 445 nm (the I605 / I445 value was approximately 2.25 - 2.51), while the I605 / I445 value was approximately 0.89 after adding borax, indicating that this method has good selectivity. When borax was added to the samples containing various interfering substances, the I605 / I445 value decreased from 2.25 - 2.51 to 0.88 - 0.92( Figure 4 (b) The relative standard deviation / RSD% was 0.74 - 6.53%), indicating that the ratiometric fluorescence analysis method based on TPQDs has significant anti-interference ability.

[0054] It has high sensitivity and can meet the detection of trace borax.

[0055] As can be seen from Figure 5 , the fluorescence emission at 445 nm increased with the increase of borax concentration (0 - 30000 μg / L), and it was more obvious compared to the fluorescence emission at 605 nm. As shown in Figure 5 (b), I605 / I445 showed a linear relationship with borax concentration C in the range of 0 - 300 μg / L (RSD% was 1.37 - 4.91%), and the linear equation was I605 / I445 = -0.0044C + 2.9309 (R2 = 0.9961). The lowest detectable concentration of borax by this method was 4.77 μg / L.

[0056] Visual fluorescence method for the detection of borax.

[0057] Figure 6 Figure shows the photos of TPQDs containing different concentrations (0 - 30000 μg / L) of borax under ultraviolet light. As the concentration of borax increased, the color gradually changed from purple to light blue-violet. When a high concentration (0.5 - 30 mg / L) of borax was added to the TPQDs suspension, the color change was almost imperceptible. Figure 6 It shows that the 1000IG / I (I = IR + IG + IB) value increased rapidly with the increase of borax concentration, where IR, IG, and IB were the average values of the red (R), green (G), and blue (B) intensities obtained through Photoshop 8.0, respectively. The RSD% was 6.01 - 12.11%. The lowest detectable concentration of borax by the visual fluorescence method based on TPQDs was 150 μg / L.

[0058] The present invention established a ratiometric fluorescence analysis method for borax (see Figure 7):TPQDs were constructed by mixing 60 μL of 30 g / L PVA, 50 μL of modified QDs suspension, 20 μL of 10 g / L TPE, and 1820 μL of water. After adding borax, compared with the fluorescence emission of QDs (at about 605 nm), the fluorescence emission of TPE (around 445 nm) gradually becomes stronger. The reason is that the addition of borax increases the viscosity, restricting the intramolecular motion of TPE, thereby enhancing the emission of TPE through the AIE effect. Furthermore, the detection of borax is achieved by comparing the change in the ratio of the fluorescence intensities of QDs and TPE.

[0059] Evaluation of the application effect of the ratiometric fluorescence analysis method based on TPQDs.

[0060] Table 1 Results of the detection of borax by the ratiometric fluorescence analysis method and ICP-OES method

[0061]

[0062]

[0063] As can be seen from Table 1, the recovery rates of the ratiometric fluorescence analysis method based on TPQDs for meat samples all exceeded 75%. This method was verified by the ICP-OES method. The results show that the present invention has quite good application prospects.

[0064] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat, characterized in that: The ratio fluorescence analysis method includes the following steps: Step 1. Preparation of the multifunctional ratio fluorescence probe TPQDs; Step 2. Exploration of the sensitivity, selectivity, anti-interference ability and stability of the ratio fluorescence analysis method; Step 3. Evaluation of the application effect of the ratio fluorescence analysis method; The preparation of the multifunctional ratio fluorescence probe TPQDs first synthesizes manganese-doped zinc sulfide quantum dots Mn-ZnSQDs by the chemical precipitation method; The specific method for preparing the multifunctional ratio fluorescence probe TPQDs: Mix 60 μL of 30 g / L polyvinyl alcohol PVA, 50 μL of QDs suspension, 20 μL of 10 g / L tetraphenylethylene TPE and 1820 μL of water to construct the probe TPQDs.

2. The ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat according to claim 1, characterized in that: The specific steps for synthesizing manganese-doped zinc sulfide quantum dots Mn-ZnSQDs by the chemical precipitation method are as follows: Step 1. Under nitrogen protection, stir 10 mL of 2.5 mol / L zinc sulfate, 10 mL of 0.1 mol / L manganese chloride solution and 20 mL of ultrapure water at room temperature for 5 minutes; Step 2. Dropwise add 5 mL of 2.5 mol / L sodium sulfide solution to the mixture; Step 3. After 2 hours, centrifuge and wash the above mixture 5 times with ethanol / water at V / V = 1:1 to obtain the product; Step 4. Dry the final product in a vacuum oven at 100 °C.

3. The method for ratiometric fluorescence analysis of sodium tetraborate on the surface of fresh meat based on aggregation-induced emission enhancement according to claim 1, wherein: In the preparation of the multifunctional ratio fluorescence probe TPQDs, the reference emission comes from QDs and the responsive emission comes from TPE. After adding borax, borax reacts with PVA, increasing the viscosity of the system. As the viscosity increases, the intramolecular motion of TPE molecules is restricted, enhancing the emission of TPE, namely the AIE effect. By comparing the ratio I 605 / I 445 change, the concentration of borax can be determined.

4. The ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat according to claim 1, wherein: The exploration of the sensitivity of the ratio fluorescence analysis method: Add 50 μL of borax solutions with different concentrations of 0, 0.2, 0.8, 6, 8, 12, 20, 40, 400 and 1200 mg / L to TPQDs; the actual concentrations of borax in the mixture are 0, 5, 20, 150, 200, 300, 500, 1000, 10000 and 30000 μg / L respectively; then, immediately transfer the mixture to a 60 °C water bath and keep it for 18 minutes; finally, record the fluorescence spectra of the mixture at an excitation wavelength of 300 nm respectively; in addition, use the visual fluorescence method to explore the sensitivity of TPQDs in 50 μL of borax solutions with different concentrations of 1200, 400, 40, 20, 12, 8, 6 and 0 mg / L, and the actual concentrations of borax are 30000, 10000, 1000, 500, 300, 200, 150 and 0 μg / L respectively.

5. The ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat according to claim 1, characterized in that: The exploration of the selectivity of the ratio fluorescence analysis method: Select common preservatives such as acetic acid AA, benzoic acid BA and lactic acid LA, as well as main components or similar substances in meat such as cholesterol Ch, collagen polypeptide CP, thiamine hydrochloride TH, bovine serum albumin BSA and L-cysteine LC as interfering substances, and add 50 μL of the interfering substances and 40 mg / L of borax solution to TPQDs respectively to discuss the selectivity of the method; then, drop 50 μL of 40 mg / L borax solution into the TPQDs solution containing different interfering substances to explore its anti-interference ability respectively.

6. The ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat according to claim 1, characterized in that: The exploration of the stability of the ratio fluorescence analysis method: The stability is mainly related to the modified quantum dots QDs. The QDs are stored in a refrigerator at 2-6 °C, and the fluorescence spectra of the QDs are collected every five days for one month.

7. The method for ratiometric fluorescence analysis of sodium tetraborate on the surface of fresh meat based on aggregation-induced emission enhancement according to claim 1, wherein: Evaluation of the application effect of the ratio fluorescence analysis method For the fluorescence method, 40 μL of 1 g / L borax solution was evenly dropped onto the surface of 2 g of pork or chicken, with a contamination amount of 20 mg / kg. After the water evaporated, the contaminated meat was placed in a 50 mL centrifuge tube, and 20 mL of water was added. Then, after shaking for 5 minutes and removing the meat pieces, contaminated water containing some organic matter was obtained; after centrifuging at 4000 rpm for 5 minutes, small pieces of meat or meat particles were removed, 10 mL of the upper layer solution was added to 5 mL of n-hexane, and the mixture was shaken for 1 minute; after the mixture was layered, the water contaminated with borax was obtained from the supernatant; finally, the fluorescence spectrum of TPQDs containing 120 μL of contaminated water was collected, and the concentration of the contaminated water was calculated through the standard curve.

8. The ratio fluorescence analysis method based on aggregation-induced emission enhancement for sodium tetraborate on the surface of fresh meat according to claim 7, characterized in that: The evaluation of the application effect of the ratio fluorescence analysis method For the visualization fluorescence method, the dropwise method was used for borax sensing. 20 μL of 0, 40, 100, 200, 400, and 1000 mg / L borax solutions were respectively dropped onto the surface of meat. The contaminated area of pork was 3.14 mm 2 , and the contaminated area of chicken was 4.91 mm 2 ; After the water evaporated, the 5-fold concentrated TPQDs were dropped onto the same position; Then, the photos of the meat surface containing TPQDs and different concentrations of borax were recorded under 254 nm ultraviolet light; In addition, the proposed TPQDs-based ratio fluorescence method was verified by inductively coupled plasma spectroscopy ICP-OES method.

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