Luminol hydrogen peroxide chemiluminescence system and application thereof in nitrite detection

Abstract

The invention discloses a luminol hydrogen peroxide chemiluminescence system and application thereof in nitrite detection, and belongs to the technical field of food safety detection. The luminol hydrogen peroxide chemiluminescence system comprises a luminol reagent, a hydrogen peroxide solution and an iron MOF dispersion liquid. The large specific surface area and abundant active sites introduced by the iron MOF can load more to-be-detected substances or luminol molecules, so that the combination probability with a target detection substance can be increased, a detection signal can be amplified, and high-sensitivity detection of nitrite in food can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of food safety detection, and in particular relates to a luminol hydrogen peroxide chemiluminescence system and its application in nitrite detection. Background Art

[0002] As an important analytical tool, chemiluminescence analysis technology has a wide range of applications in food safety, environmental monitoring, biomedical research, and other fields. In recent years, with continuous technological advancements and innovations, the sensitivity and accuracy of chemiluminescence analysis technology have been significantly improved, while also becoming simpler and faster to operate. In chemiluminescence analysis technology, luminol and its derivatives are among the most commonly used luminescent reagents. They react with oxidants such as hydrogen peroxide to produce a strong chemiluminescent signal that can be used to detect a variety of target analytes. This technical system has the advantages of rapid response, high sensitivity, and simple operation, and is therefore widely used in various analytical and detection fields.

[0003] However, the existing luminol hydrogen peroxide luminescence system has the following defects:

[0004] 1) Active site limitation: Iron ions are dispersed in the solution, and the number of effective catalytic active sites per unit volume is relatively limited. In addition, the lack of an ordered structure hinders the reactant molecules from fully contacting the active sites, thus limiting the catalytic efficiency.

[0005] 2) Susceptible to environmental interference: It is sensitive to reaction conditions. When the pH of the luminol solution is adjusted to 11, it is easy to hydrolyze and form a precipitate, resulting in unstable catalytic activity and difficulty in maintaining efficient catalysis.

[0006] 3) Difficulty in controlling the reaction path: Due to the lack of specific spatial structural constraints, the reaction path cannot be precisely controlled, which can easily trigger side reactions and reduce the selectivity of the target luminescence reaction of luminol-hydrogen peroxide.

[0007] 4) Complex separation and recovery: It exists in the solution in the form of ions and is difficult to separate by simple physical methods. Complex means are required, and the recovery process is prone to loss. Summary of the Invention

[0008] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a luminol hydrogen peroxide chemiluminescence system and its application in nitrite detection, which solves the problems in the prior art.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] A luminol-hydrogen peroxide chemiluminescence system comprises a luminol reagent, a hydrogen peroxide solution and an iron MOF dispersion.

[0011] Furthermore, the concentration of the luminol reagent is 0.05 mol / L, and the volume fraction of the hydrogen peroxide solution is 30%.

[0012] Furthermore, the concentration of the iron MOF dispersion is 0.048 g / 10 ml.

[0013] Furthermore, the volume ratio of the luminol reagent, the hydrogen peroxide solution and the iron MOF dispersion is 1:1:1.

[0014] Furthermore, the preparation process of the luminol reagent is as follows: luminol powder is mixed and dissolved with pure water, and then NaOH powder is added to adjust the pH of the solution to 11; finally, pure water is added to dilute the solution to obtain the desired concentration of luminol reagent.

[0015] The above-mentioned luminol hydrogen peroxide chemiluminescence system is used to detect the concentration of nitrite in food.

[0016] A method for detecting nitrite concentration in food, using the above-mentioned luminol hydrogen peroxide chemiluminescence system, comprises the following steps:

[0017] Step 1: Mix the Fe-MOF dispersion and hydrogen peroxide solution to obtain a mixed solution, and drop multiple groups of known nitrite solutions with different concentration gradients into the mixed solution; then place the solution in a dark box, add luminol reagent, and close the dark box.

[0018] Step 2: Photograph and record the luminescence phenomenon of the solution in the dark box; quantitatively analyze the luminescence intensity of the captured image to construct a linear relationship between the concentration of the nitrite solution and the luminescence intensity;

[0019] Step 3: Mix the Fe-MOF dispersion and hydrogen peroxide solution, and add the food sample liquid to be tested; then place it in a dark box, add luminol reagent, and then close the dark box;

[0020] Step 4: Photograph and record the luminescence phenomenon of the solution in the dark box in step 3; quantitatively analyze the luminescence intensity of the captured image, and finally substitute the read light intensity data into the linear relationship constructed in step 2 to obtain the concentration of nitrite in the food to be tested.

[0021] Furthermore, the luminescence intensity of the captured images was quantitatively analyzed using ImagePro software.

[0022] Furthermore, the food sample liquid is prepared by chopping the food into pieces and soaking the food in distilled water, and then filtering to remove food residues, leaving the filtrate as the food sample liquid.

[0023] A food safety detection device comprises the above-mentioned luminol hydrogen peroxide chemiluminescence system.

[0024] Beneficial effects of the present invention:

[0025] 1. The luminescent system of the present invention features a highly efficient Fe-MOF catalyst, which has a high specific surface area. This provides more active sites for the reaction, allowing reactants to more fully contact the catalyst, accelerating the reaction rate and prolonging the catalytic reaction time. In contrast, Fe ions are dispersed in solution, with relatively few accessible reaction sites. Furthermore, their rich porous structure facilitates the diffusion of reactants into the catalyst, increasing the contact area and reaction efficiency, whereas Fe ions lack similar structural advantages.

[0026] 2. Fe-MOF is a metal-organic framework formed by self-assembly of metal ions and organic ligands through coordination bonds, resulting in a well-organized microstructure. This structure imparts unique properties, such as the confinement effect, which allows the enrichment and localization of reaction substrates within its pores, thus promoting the reaction. Free Fe ions, however, lack this ordered microenvironment, resulting in relatively low reaction selectivity and efficiency.

[0027] 3. The structure and active site properties of Fe-MOF give it excellent selectivity for specific reactions. In complex reaction systems, it can precisely catalyze the target reaction and reduce the occurrence of side reactions.

[0028] 4. After testing, Fe-MOF can be recycled and reused by collecting the waste liquid, centrifuging it, taking the solids after centrifugation, washing them, and drying them. After proper treatment, its structure and catalytic performance can remain stable, allowing it to be reused multiple times, reducing its cost.

[0029] 5. This invention offers high sensitivity in food safety testing: The large surface area and abundant active sites of the iron MOF allow it to carry more recognition molecules (e.g., the substance to be detected) or signal molecules (e.g., luminol). This increases the probability of binding with the target substance and amplifies the detection signal, thereby enabling highly sensitive detection of trace harmful substances (e.g., nitrite) in food.

[0030] 6. The luminescent system of the present invention has efficient mass transfer and catalytic properties, which can accelerate detection reactions and shorten detection time. In the context of rapid on-site food safety testing, it can quickly provide test results and respond to food safety emergencies in a timely manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 is the XRD pattern of the iron MOF of the present invention;

[0033] Figure 2 is a SEM characterization image of the iron MOF of the present invention;

[0034] Figure 3 is a curve corresponding to the light intensity IOD and nitrite concentration of the luminescence system in Example 1;

[0035] Figure 4 is the EPR comparison curve of the two luminescent systems of the present invention;

[0036] Figure 5 This is the result of the catalyst quantitative experiment. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] A luminol-hydrogen peroxide chemiluminescent system comprises a luminol reagent, a hydrogen peroxide solution, and an iron metal organic framework (MOF) dispersion. When these three components are mixed, the luminol reagent reacts with the oxygen produced by the decomposition of hydrogen peroxide to generate excited 3-aminophthalic acid. When the excited 3-aminophthalic acid returns to its ground state, it releases energy, resulting in blue light. Simultaneously, the iron MOF, as a metal-organic framework, acts as a highly efficient catalyst for the luminol-hydrogen peroxide system.

[0039] Among them, the concentration of luminol reagent is 0.05 mol / L, the volume fraction of hydrogen peroxide solution is 30% (i.e., 9.79 mol / L); the concentration of iron MOF dispersion is 0.048 g / 10 ml; and the volume ratio of luminol reagent, hydrogen peroxide solution and iron MOF dispersion is 1:1:1.

[0040] The preparation process of the iron MOF dispersion is as follows: the iron MOF powder is mixed and dispersed with distilled water to obtain a dispersion with a concentration of 0.0032g / 10ml, and this is doubled to prepare an iron MOF dispersion with a concentration of 15 times, that is, a concentration of 0.048g / 10ml.

[0041] To find the optimal catalyst dosage, quantitative experiments were conducted using the same luminol and hydrogen peroxide solutions. The experimental process involved preparing an initial Fe-MOF solution at 0.0032g / 10ml, and then adding 5, 10, 12.5, 15, 17.5, and 20 times the concentration. The Fe-MOF dispersions at these different concentrations catalyzed the luminol-H2O2 system, and luminescence images were captured. The luminol dosage remained at 0.05mol / L, and the hydrogen peroxide concentration was 30% by volume (i.e., 9.79mol / L).

[0042] The experimental results are as follows Figure 5 As shown; it can be clearly seen that when the Fe-MOF dispersion is selected with a concentration of 15 times the order of magnitude, the luminescence brightness is the highest; therefore, the luminescence system of the present invention adopts a Fe-MOF dispersion with a concentration of 0.048g / 10ml.

[0043] The configuration process of the luminol hydrogen peroxide chemiluminescence system includes the following steps:

[0044] S1, prepare luminol reagent;

[0045] Accurately weigh luminol powder, place it in a container, add pure water, and shake thoroughly to dissolve it. Subsequently, accurately weigh NaOH powder and add it to the above solution. Use a precision pH meter (such as a pH meter) to adjust the solution to a pH of 11. Transfer the resulting solution to a volumetric flask, dilute to the mark with pure water, and shake well to obtain alkaline luminol reagent (0.05 mol / L). The reaction conditions are room temperature and a pH of 11.

[0046] S2, preparing the iron MOF dispersion;

[0047] The iron MOF powder was mixed with pure water and stirred until completely dispersed to obtain a Fe-MOF dispersion with a concentration of 0.048 g / 10 ml. The volume fraction of the hydrogen peroxide solution was 30% (i.e., 9.79 mol / L).

[0048] The luminol reagent, the hydrogen peroxide solution, and the iron MOF dispersion liquid jointly constitute a luminol hydrogen peroxide chemiluminescence system. It should be noted that the luminol reagent, the hydrogen peroxide solution, and the iron MOF dispersion liquid in the system do not need to be mixed before food detection; during food detection, the hydrogen peroxide solution and the iron MOF dispersion liquid are mixed first, then the food sample liquid to be detected is added, finally the luminol reagent is added to emit light, and the analysis light intensity is photographed.

[0049] As the detected substance, nitrite can inhibit the generation of superoxide anion in the reaction, leading to the reduction of generated free radicals, thereby inhibiting the generation of energy and reducing the light intensity. Different concentrations of nitrite have different inhibition degrees on the system, and the higher the concentration, the higher the inhibition degree, so that the linear relationship between the concentration of nitrite and the light intensity is determined to determine the concentration of the nitrite to be detected.

[0050] The process of using the luminol hydrogen peroxide chemiluminescence system to detect the concentration of nitrite in food is as follows:

[0051] Step 1: Use a syringe to suck Fe-MOF dispersion liquid (0.048 g / 10 ml) and uniformly drop it on the surface of a surface dish; then use a syringe to accurately suck hydrogen peroxide solution (9.79 mol / L) and slowly drop it into the surface dish containing the Fe-MOF solution to obtain a mixed solution; prepare multiple groups of nitrite solutions with different known concentration gradients, and drop them into the mixed solution in turn; after the above operation, carefully place the surface dish in a dark box; then use a syringe to suck luminol reagent (0.05 mol / L) and quickly drop it into the mixed system of the surface dish; immediately close the dark box to avoid external light interference. Use a camera to record the light emission phenomenon of the solution in the dark box. After the shooting is completed, use ImagePro software to quantitatively analyze the light intensity of the photographed image; construct the linear relationship between the concentration of the nitrite solution and the light intensity.

[0052] Step 2, the Fe-MOF dispersion liquid (0.048 g / 10 ml) is uniformly dropped on the surface of the surface plate by using the syringe; then the hydrogen peroxide solution (9.79 mol / L) is precisely sucked by using the syringe again and slowly dropped into the surface plate containing the Fe-MOF solution to obtain a mixed solution; then the food sample solution to be detected is added into the mixed solution; after the above operation, the surface plate is carefully placed in the dark box; then the luminol reagent (0.05 mol / L) is quickly dropped into the mixed system of the surface plate by using the syringe; immediately, the dark box is quickly closed to avoid the interference of external light on the experiment. The camera is used to record the luminescence phenomenon of the solution in the dark box. After the shooting is completed, the ImagePro software is used to quantitatively analyze the luminescence intensity of the photographed image; finally, the read light intensity data is brought into the linear relationship constructed in step 1, and the concentration of nitrite in the food sample to be detected can be obtained.

[0053] It is worth mentioning that the process of quantitatively analyzing the luminescence intensity of the photographed image by using the ImagePro software includes: opening the ImagePro software, importing the image to be measured by the "file-open" or drag-in method, and converting it into a gray-scale image if necessary in the "image" or "color" related options; then the measurement area (the whole image can be omitted) is drawn by using the selection tool (rectangle, ellipse, polygon frame or lasso, etc.), the brightness related indicators (such as gray value, brightness value, etc.) are checked in the measurement setting interface of the "measurement" or "analysis" option and other parameters are set as needed; after completion, the "measurement" button is clicked, the software automatically calculates the brightness value, and the average, maximum and minimum brightness values and other results are recorded in time after the measurement is completed; the luminescence intensity data is read.

[0054] The technical solutions of the present application will be described in detail below by the following examples and comparative examples. In the examples and comparative examples, the sources of the raw materials are as follows:

[0055] Luminol is purchased from Shanghai Aldrin Biochemical Technology Co., Ltd.;

[0056] 30vt% hydrogen peroxide solution (H2O2) is purchased from Shanghai Aldrin Biochemical Technology Co., Ltd.;

[0057] Iron MOF (Fe-MOF): MIL101 (Fe) MOF is purchased from Suzhou Kaifa New Material Technology Co., Ltd.

[0058] Example 1

[0059] In this example, the luminol hydrogen peroxide chemiluminescence system (luminol+H2O2+Fe-MOF) is prepared, and the linear relationship between the concentration of nitrite and the luminescence intensity is constructed, so as to detect the concentration of nitrite in the food sample solution.

[0060] 1) Prepare 0.05 mol / L luminol reagent;

[0061] Accurately weigh 0.0886 g of luminol powder and place it in a suitable container. Add 5 mL of pure water and shake thoroughly to dissolve. Subsequently, accurately weigh 0.02 g of NaOH powder and add it to the above solution. Use a precision pH measuring instrument (such as a pH meter) to adjust the pH of the solution to 11. Transfer the resulting solution to a 10 mL volumetric flask, dilute to the mark with pure water, and shake well to obtain alkaline luminol reagent (0.05 mol / L). The reaction temperature is room temperature; the pH is 11.

[0062] 2) Prepare 0.048 g / 10 ml of Fe-MOF dispersion;

[0063] The concentration of the Fe-MOF dispersion is 0.048g / 10ml. The preparation process is as follows: 0.048g of Fe-MOF powder is placed in a test tube, 10ml of pure water is added, and the resulting solution is thoroughly shaken to dissolve. The resulting solution is transferred to a 10ml container, dilute to the mark with pure water, and shaken to obtain the Fe-MOF dispersion. The hydrogen peroxide solution was purchased directly.

[0064] 3) preparing sodium nitrite solutions of different concentrations;

[0065] The concentration range of the prepared samples was from 10 -1 M to 10 -10 M sodium nitrite solution. First, use an analytical balance to accurately weigh 0.69g of sodium nitrite. Place the sodium nitrite in a small beaker, add a small amount of deionized water, and stir to completely dissolve it. Transfer the solution to a 100mL volumetric flask, rinse the small beaker with deionized water several times, transfer the washing liquid to the volumetric flask, and then dilute to the scale line with deionized water, shake well, and obtain a sodium nitrite mother liquor with a concentration of 0.1M. Starting from this mother liquor, gradually dilute to the target concentration by a 10-fold dilution method. The specific operation is as follows: take 1mL of the mother liquor and transfer it to a 10mL volumetric flask, dilute to the scale line with deionized water, shake well, and obtain 10 -2 M solution; and so on, repeat the above operation to obtain 10 -3 M, 10 - 4 M... until 10 -10 M of sodium nitrite solution.

[0066] 4) Use a dispenser to accurately draw 8 μL of the Fe-MOF dispersion (0.048 g / 10 ml) and evenly drip it onto the surface of a watch glass. Then, use the dispenser again to accurately draw 8 μL of hydrogen peroxide solution (9.79 mol / L) and slowly drip it into the watch glass containing the Fe-MOF solution to create a mixed solution. Add multiple sodium nitrite solutions of varying concentrations to the mixed solution. After completing these steps, carefully place the watch glass in a darkroom. Next, use a dispenser to draw 8 μL of luminol (0.05 mol / L) and quickly drip it into the mixture in the watch glass. Quickly close the darkroom to prevent external light from interfering with the experiment. Use a camera to record the luminescence of the solution within the darkroom. After recording, use ImagePro software to quantitatively analyze the luminescence intensity of the captured images. A linear relationship between sodium nitrite concentration and luminescence intensity was constructed.

[0067] The curve between the concentration of sodium nitrite solution and luminescence intensity is as follows: Figure 3 As shown in the figure, the brightness of the luminescence system increases as the sodium nitrite concentration decreases. The higher the sodium nitrite concentration, the greater the degree to which it inhibits the production of superoxide anions and free radicals by luminol. This inhibits the luminescence reaction and causes the light intensity to decrease.

[0068] 5) Next, prepare a food sample solution. In this example, 1g of vegetables was chopped and soaked in 10ml of distilled water for 15 minutes. The food residue was filtered, and the filtrate was retained to obtain the food sample solution.

[0069] 6) The nitrite concentration of the food sample liquid is tested in the following process:

[0070] Use a shotgun to accurately draw 8μL of Fe-MOF dispersion (0.048g / 10ml) and evenly drip it on the surface of the watch glass; then use the shotgun again to accurately draw 8μL of hydrogen peroxide solution (9.79mol / L) and slowly drip it into the watch glass containing the Fe-MOF solution to obtain a mixed solution; then take 8μL of the food sample to be tested and add it to the above mixed solution; after completing the above operations, carefully place the watch glass in a dark box; then, use a shotgun to draw 8μL of luminol reagent (0.05mol / L) and quickly add it to the mixed system of the watch glass; then quickly close the dark box mouth to avoid external light interfering with the experiment. Use a camera to record the luminescence phenomenon of the solution in the dark box. After the shooting is completed, use ImagePro software to quantitatively analyze the luminescence intensity of the captured image; finally, the read light intensity data is as follows Figure 3 The linear curve shown can be used to obtain the concentration of nitrite in the food to be tested.

[0071] In this embodiment, the high-efficiency catalyst Fe-MOF was characterized by X-ray diffraction (XRD), as shown in FIG. Figure 1 As shown, the results show that the sample has obvious diffraction peaks at multiple angles, indicating that the atoms inside Fe-MOF are arranged in a periodic and orderly manner, with typical crystal structure characteristics, which is different from completely disordered amorphous materials. Specifically, there are significant characteristic diffraction peaks near 2θ of 8.9°, 17.2°-18.26°, 26.12°-27.9° and 28.12°-28.53°, and the intensity of each peak is relatively high. According to the XRD principle, the peak intensity is closely related to the crystallinity of the material. The high-intensity diffraction peak means that Fe-MOF has a high degree of crystallinity, and its internal atomic arrangement is highly periodic and ordered, which provides a structural basis for the material to exhibit excellent performance in catalytic applications. 8.9°, 17.2° and 27.9° are the characteristic XRD absorption peaks of Fe-MOF, which is consistent with the literature reports. It shows that Fe-MOF has better catalytic performance than ordinary iron ions.

[0072] SEM characterization images of iron MOF are shown in Figure 2. Figure 2 As shown, Figure 2 (a) and (b) in the figure respectively indicate SEM characterization images at different scales. It can be seen that the iron MOF has an obvious crystal structure, which is roughly consistent with the theoretical expected results. It also proves the reliability and high performance of this efficient catalyst, and provides a strong basis for further large-scale production and practical application.

[0073] Comparative Example 1

[0074] In this comparative example, a luminol hydrogen peroxide chemiluminescence system (luminol+H2O2) was used, and the preparation process was as follows:

[0075] 1) Accurately weigh 0.0886 g of luminol powder and place it in a suitable container. Add 5 mL of pure water and shake thoroughly to dissolve. Subsequently, accurately weigh 0.02 g of NaOH powder and add it to the above solution. Adjust the pH of the solution to approximately 11 using a precision pH meter (e.g., a pH meter). Transfer the resulting solution to a 10 mL volumetric flask, dilute to the mark with pure water, and shake well to obtain the alkaline luminol reagent.

[0076] 2) Take 10 ml of 30% volume fraction hydrogen peroxide and place it in a test tube.

[0077] Take 8 μL of luminol reagent and 8 μL of hydrogen peroxide solution respectively to form a luminol+H2O2 system.

[0078] Comparative experiment:

[0079] By comparing the EPR images of the two different luminescence systems in Example 1 (luminol+H2O2+Fe-MOF) and the comparative example (luminol+H2O2), as shown in FIG. Figure 4 As shown; the black line represents luminol+H2O2, and the red line represents luminol+H2O2+Fe-MOF;

[0080] Figure 4 It can be seen that in the Luminol+H2O2 system, the black curve (containing only luminol+H2O2) did not detect obvious free radical characteristic signals, indicating that the free radicals generated by the spontaneous decomposition of H2O2 in this system were very few; while the red curve (Luminol+H2O2+Fe-MOF) showed significant free radical resonance signals (such as typical ·OH or ·O2 - This result directly demonstrates that Fe-MOF can efficiently catalyze the decomposition of H2O2 to generate free radicals, significantly increasing the free radical concentration in the system and accelerating the catalytic process through a free radical-mediated reaction pathway. This indicates that Fe-MOF can catalyze H2O2 to generate free radicals, thereby promoting the luminescence reaction and demonstrating the excellent catalytic performance of Fe-MOF.

[0081] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0082] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A luminol hydrogen peroxide chemiluminescence system, characterized in that: include: Luminol reagent, hydrogen peroxide solution, and iron MOF dispersion.

2. A luminol hydrogen peroxide chemiluminescence system according to claim 1, characterized in that: The concentration of the luminol reagent is 0.05 mol / L, and the volume fraction of the hydrogen peroxide solution is 30%.

3. A luminol hydrogen peroxide chemiluminescence system according to claim 2, characterized in that: The concentration of the iron MOF dispersion is 0.048 g / 10 ml.

4. A luminol hydrogen peroxide chemiluminescence system according to claim 1 or 3, characterized in that: The volume ratio of the luminol reagent, hydrogen peroxide solution and iron MOF dispersion is 1:1:

1.

5. A luminol hydrogen peroxide chemiluminescence system according to claim 1, characterized in that: The preparation process of the luminol reagent is as follows: luminol powder is mixed and dissolved with pure water, then NaOH powder is added to adjust the pH of the solution to 11; and finally pure water is added to dilute the solution to obtain the desired concentration of luminol reagent.

6. Use of the luminol hydrogen peroxide chemiluminescence system according to any one of claims 1 to 5 in detecting nitrite concentration in food.

7. A method for detecting nitrite concentration in food, characterized in that: Using a luminol hydrogen peroxide chemiluminescence system according to any one of claims 1 to 5, comprising the following steps: Step 1: Mix the Fe-MOF dispersion and hydrogen peroxide solution to obtain a mixed solution, and drop multiple groups of known nitrite solutions with different concentration gradients into the mixed solution; then place the solution in a dark box, add luminol reagent, and close the dark box. Step 2: Photograph and record the luminescence phenomenon of the solution in the dark box; quantitatively analyze the luminescence intensity of the captured image to construct a linear relationship between the concentration of the nitrite solution and the luminescence intensity; Step 3: Mix the Fe-MOF dispersion and hydrogen peroxide solution, and add the food sample liquid to be tested; then place it in a dark box, add luminol reagent, and then close the dark box; Step 4: Photograph and record the luminescence phenomenon of the solution in the dark box in step 3; quantitatively analyze the luminescence intensity of the captured image, and finally substitute the read light intensity data into the linear relationship constructed in step 2 to obtain the concentration of nitrite in the food to be tested.

8. The method for detecting nitrite concentration in food according to claim 7, wherein: The luminescence intensity of the captured images was quantitatively analyzed using ImagePro software.

9. The method for detecting nitrite concentration in food according to claim 7, wherein: The food sample liquid is prepared by chopping the food into small pieces and soaking it in distilled water, then filtering to remove the food residue, and leaving the filtrate as the food sample liquid.

10. A food safety testing device, characterized in that: The invention comprises a luminol hydrogen peroxide chemiluminescence system according to any one of claims 1 to 5.

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