Phosphorescent detection of levofloxacin in complex matrix and its application

Abstract

The application provides a phosphorescence detection method for levofloxacin in a complex matrix, wherein the complex matrix is an aqueous heterogeneous system, and the method comprises the following steps: adding a demulsifier A, a flocculant B and an acid C into the complex matrix, centrifuging to obtain supernatant, and neutralizing the supernatant with an alkali to obtain an extraction liquid A; the demulsifier A is polyethylene oxide; the flocculant B is any one of polyferric sulfate and polyaluminum sulfate or a mixture of the two; boric acid is mixed with the extraction liquid A, a catalyst D and a catalyst E are added into the mixture, and heating is performed to obtain a product B, the catalyst D is a cobalt salt, and the catalyst E is an iodine salt; the product B is excited by ultraviolet light, and phosphorescence detection is performed to obtain a detection result of the levofloxacin in the complex matrix. The application can realize quantitative or qualitative detection of trace levofloxacin in an extraction liquid of a complex matrix, and has the advantages of high detection sensitivity, convenient operation, obvious phenomenon and rapid detection.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of food safety, in particular to a method for detecting levofloxacin in complex matrix by phosphorescence and application thereof. BACKGROUND

[0002] Levofloxacin is a broad-spectrum antibacterial drug of quinolones, which is widely used in the treatment of infection, aquaculture and other fields. According to the list of non-illegal edible substances that may be added to food issued by the former Ministry of Health, quinolone antibiotics may be illegally added to spicy hot pot. The residual quinolone antibiotics in the human body can cause liver and kidney toxicity and produce drug resistance, endangering human health. Therefore, it is necessary to develop a rapid detection method for quinolone antibiotics. According to the case and pharmacokinetic data conversion, the concentration of levofloxacin in the matrix should be greater than 1 mg / mL to exert the anti-diarrhea treatment effect. Spicy hot pot is a suspended emulsion containing a large amount of protein, seasoning and oil and other substances. It is difficult to enrich levofloxacin with good water solubility by liquid-liquid extraction method, and usually solid-phase extraction method is used in combination with large instruments for detection.

[0003] At present, some literatures have studied the phosphorescence properties of materials using levofloxacin as raw material. For example, in Chinese patent application CN119505893A, levofloxacin and acid were used to generate carbon quantum dots with phosphorescence properties by hydrothermal method, in which the minimum mass ratio of levofloxacin to acid was 1:10. In Chinese patent application CN112500740A, levofloxacin was used to generate phosphorescent carbon dots by solvothermal reaction, in which the minimum mass-volume ratio of levofloxacin to solvent was 1:1000. In Chinese patent application CN118620614A, levofloxacin and boric acid were used to generate phosphorescent carbon dots, in which the minimum mass ratio of levofloxacin to acid was 1:300. In these studies, it is believed that levofloxacin generates phosphorescence by generating carbon quantum dots after reaction. At the same time, these studies lack the study of the levofloxacin content and the phosphorescence intensity, and lack the phosphorescence of levofloxacin content less than one thousandth in the system. The detection effect of trace levofloxacin is unknown.

[0004] Phosphorescence is a kind of molecular luminescence phenomenon accompanied by fluorescence. Phosphorescence has a long lifetime and can be observed by the naked eye, thereby avoiding the interference of fluorescent substances in the matrix. The use of phosphorescence detection has good sensitivity, selectivity and can effectively reduce the interference of background. Levofloxacin has a conjugated structure basis to produce phosphorescence, but due to the presence of a diazine ring that can rotate in the molecule, it is difficult to produce long-lifetime room-temperature phosphorescence. Boric acid can stabilize the highly conjugated molecular skeleton of levofloxacin by forming mixed anhydride and hydrogen bond interaction, and isolate water and oxygen from quenching phosphorescence, thereby producing room-temperature long-lifetime phosphorescence.

[0005] The above information disclosed in the Background section is only for enhancing the understanding of the background of the present application, and therefore can include information that does not constitute prior art that is already known in the art. SUMMARY

[0006] The present application aims to solve at least one of the technical problems in the related art to some extent.

[0007] To this end, the present application provides a phosphorescence detection method for levofloxacin in a complex matrix and an application thereof, which reduces the interference of inner filter effect on phosphorescence detection, so as to realize rapid detection of trace levofloxacin, and has high detection sensitivity, convenient operation and obvious phenomenon.

[0008] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] According to the phosphorescence detection method for levofloxacin in a complex matrix provided by the first aspect of the present application, the complex matrix is an aqueous heterogeneous system, and the phosphorescence detection method comprises:

[0010] A demulsifier A, a flocculant B and an acid C are added to the complex matrix, the supernatant is taken by centrifugation and neutralized with a base to obtain an extract liquid A; the demulsifier A is selected from polyethylene oxide, and the concentration range thereof is 0.01 g / L to 10 g / L; the flocculant B is selected from any one or a mixture of the two of polymeric ferric sulfate and polymeric aluminum sulfate; the concentration range of the acid C is 1 g / L to 1000 g / L; and the mass ratio of the complex matrix, the demulsifier A, the flocculant B and the acid C is 1:0.1:0.01-0.2:0.1.

[0011] After the boric acid is mixed with the extract liquid A, a catalyst D and a catalyst E are added thereto and heated to obtain a product B; the catalyst D is selected from cobalt salt, and the catalyst E is selected from iodine salt; and the mass ratio of the boric acid, the extract liquid A, the catalyst D and the catalyst E is 1:0.5-100:0.005‰-5‰:0.005‰-5‰.

[0012] After the product B is excited by ultraviolet rays, phosphorescence detection is performed to obtain the detection result of levofloxacin in the complex matrix.

[0013] In some embodiments, the acid C is selected from a mixture of any one or more of formic acid, acetic acid and hydrochloric acid.

[0014] In some embodiments, the catalyst D is selected from a mixture of any one or more of cobalt chloride, cobalt nitrate and cobalt sulfate.

[0015] In some embodiments, the catalyst E is selected from a mixture of any one or more of sodium iodide and potassium iodide.

[0016] In some embodiments, the temperature used during heating is 150-300 DEG C.

[0017] In some embodiments, the excitation light wavelength used during UV excitation of the product ethyl is 340-400 nm, and the time for detecting phosphorescence is 0.1-5 s.

[0018] In some embodiments, the phosphorescence detection method further comprises:

[0019] The linear relationship between phosphorescence intensity and levofloxacin concentration is used to quantitatively or qualitatively detect the concentration of levofloxacin in the complex matrix; when used for quantitative detection, the linear detection range of the levofloxacin is 0.001-1 mg / mL, and the detection limit is 0.0004 mg / mL.

[0020] In some embodiments, when the complex matrix contains levofloxacin, the phosphorescence is yellow-green phosphorescence or the phosphorescence intensity at a detection wavelength of 500-550 nm.

[0021] According to the second aspect of the present application, the phosphorescence detection method based on any one of the embodiments of the first aspect of the present application is used for detecting trace levofloxacin in food with an aqueous heterogeneous system.

[0022] In some embodiments, the food is spicy hot pot.

[0023] Compared with the prior art, the present application has the following characteristics and beneficial effects:

[0024] The present application uses polymeric ferric sulfate and / or polymeric aluminum sulfate as a flocculant, polyethylene oxide as a demulsifier, and an acid solution mixed and extracted by centrifugation to develop a pretreatment method, which can effectively solve the problem of turbidity caused by the addition of milk powder, has good purification effect on complex matrix, and can make the complex matrix clear, avoid the shielding of phosphorescence due to internal filtration effect, and will not adsorb levofloxacin.

[0025] The present application uses cobalt salt and iodine salt to catalyze the reaction of boric acid and levofloxacin and enhance the phosphorescence of the reaction product.

[0026] In summary, the present application can be used for quantitative or qualitative detection of trace levofloxacin in complex matrix extract, and has high detection sensitivity, convenient operation, obvious phenomenon, and is beneficial to rapid detection. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The phosphorescence schematic diagram of the reaction product of boric acid and 1 mg / mL levofloxacin after 365 nm UV excitation;

[0028] Figure 2The phosphorescence spectrum of the reaction product of boric acid and levofloxacin with a content of 1 mg / mL was measured by a spectrometer at 365 nm.

[0029] Figure 3 The functional relationship between the phosphorescence intensity and the concentration of levofloxacin detected by the detection method provided in Embodiment 1 of the present application is shown in the following figure;

[0030] Figure 4 The relationship between the concentration of different purifying agents and the purifying effect of the spicy boiled base in Embodiment 1 of the present application is shown in the following figure a, b and c.

[0031] Figure 5 The effect comparison figure of not adding cobalt chloride catalyst and using cobalt chloride catalyst in Embodiment 1 of the present application is shown in the following figure.

[0032] Figure 6 The effect comparison figure of not adding sodium iodide catalyst and using sodium iodide catalyst in Embodiment 1 of the present application is shown in the following figure.

[0033] Figure 7 The nuclear magnetic resonance hydrogen spectrum before and after the reaction in step S2 of Embodiment 1 of the present application is shown in the following figure.

[0034] Figure 8 The infrared spectrum before and after the reaction in step S2 of Embodiment 1 of the present application is shown in the following figure.

[0035] Figure 9 The scanning electron microscope magnified image of the reaction product E obtained in step S2 of Embodiment 1 of the present application is shown in the following figure.

[0036] Figure 10 The influence figures of iodine content, cobalt content, reaction temperature and the mass ratio of the extraction liquid to boric acid on the phosphorescence are shown in the following figures a, b, c and d. DETAILED DESCRIPTION

[0037] The present application will be further described in details by specific embodiments in combination with the accompanying drawings. In different embodiments, similar elements are associated with similar element reference numbers. In the following embodiments, many details are described in order to make the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different cases, or can be replaced by other elements, materials or methods. In some cases, some operations related to the present application are not shown or described in the specification in order to avoid the core part of the present application being overwhelmed by too much description, and it is not necessary to describe these related operations in detail for those skilled in the art according to the description in the specification and the general technical knowledge in the art.

[0038] In addition, features described in the specification, operations or characteristics can be combined in any appropriate manner to form various embodiments. Meanwhile, the steps or actions in the method description can also be sequentially changed or adjusted in a manner obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment, and do not mean that the sequence is necessary, unless otherwise stated that a certain sequence must be followed.

[0039] The endpoints of the ranges and any values disclosed in this application are not limited to the precise values recited as the exact dimensions are not critical to the application. Any numerical value, however, can be expressed as a range to indicate that a disclosure of any value within the range is intended, including the endpoints. For values which are less than one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 as appropriate. For ranges which are less than one, those ranges are combined with the explicit declaration that the exact compositions are not intended.

[0040] The first aspect of the application provides a method for detecting levofloxacin in a complex matrix by phosphorescence, comprising:

[0041] Step S1, adding demulsifier A, flocculant B and acid C to the complex matrix, centrifuging to obtain the supernatant and neutralizing with alkali to obtain extract A; wherein the complex matrix is an aqueous heterogeneous system such as emulsion, suspension, etc.; the demulsifier A is selected from polyethylene oxide, and the concentration range is 0.01 g / L-10 g / L; the flocculant B is selected from any one of polymeric ferric sulfate and polymeric aluminum sulfate or a mixture of the two; the concentration range of the acid C is 1 g / L-1000 g / L; the mass ratio of the complex matrix, the demulsifier A, the flocculant B and the acid C is 1:0.1:0.01-0.2:0.1;

[0042] Step S2, mixing boric acid with the extract A, adding catalyst D and catalyst E and heating to obtain product B; wherein the catalyst D is selected from cobalt salt, the catalyst E is selected from iodine salt, and the mass ratio of the boric acid, the extract A, the catalyst D and the catalyst E is 1:0.5-100:0.005‰-5‰:0.005‰-5‰;

[0043] Step S3, exciting the product B with ultraviolet light and detecting the phosphorescence to obtain the detection result of levofloxacin in the complex matrix.

[0044] In some embodiments, step S1 is carried out at room temperature, and all raw materials are in liquid state except that the flocculant B is in solid state.

[0045] In some embodiments, in step S1, the acid C is selected from any one or a mixture of more than one of formic acid, acetic acid and hydrochloric acid.

[0046] It can be understood that step S1 is a pretreatment step for a complex matrix, and the complex matrix targeted by the present application is a suspended emulsion formed by adding milk powder. Step S1 has a good purification effect on the complex matrix by using polyethylene oxide as a demulsifier, polymeric ferric sulfate and / or polymeric aluminum sulfate as a flocculant, and acting together with an acid, so that the complex matrix is clarified to avoid the internal filtration effect to shield phosphorescence and will not adsorb levofloxacin. The purification effect of step S1 is good and easy to operate.

[0047] In some embodiments, in step S2, all the raw materials are solid except the extraction liquid A.

[0048] In some embodiments, in step S2, the catalyst D is selected from a mixture of any one or more of cobalt chloride, cobalt nitrate and cobalt sulfate.

[0049] In some embodiments, in step S2, the catalyst E is selected from a mixture of any one or more of sodium iodide and potassium iodide.

[0050] In some embodiments, in step S2, the temperature used during heating should be such that the boracic acid reaches the melting point and sufficiently coats the levofloxacin molecules, preferably 150°C to 300°C; the heating time is preferably 5 min to 300 min.

[0051] It can be understood that step S2 promotes the reaction of boracic acid with the carboxyl group of levofloxacin by using cobalt salt as a catalyst to stabilize levofloxacin in extraction liquid A, and the heavy atom effect provided by iodine salt together strengthens the phosphorescence of the reaction product. After the strengthening treatment of step S2, it can be used for subsequent rapid phosphorescence detection of trace levofloxacin.

[0052] In some embodiments, in step S3, the excitation light wavelength used when exciting the product B with ultraviolet light is 340 nm to 400 nm, and the detection time of phosphorescence is 0.1 s to 5 s.

[0053] In some embodiments, step S3 further comprises using the linear relationship between the phosphorescence intensity and the concentration of levofloxacin to quantitatively or qualitatively detect the concentration of levofloxacin in the complex matrix; when used for quantitative detection, the linear detection range of levofloxacin is 0.001 mg / mL to 1 mg / mL, and the detection limit is 0.0004 mg / mL.

[0054] Further, when the complex matrix contains levofloxacin, the phosphorescence is yellow-green phosphorescence or the phosphorescence intensity at a detection wavelength of 500 nm to 550 nm.

[0055] The second aspect of the present application provides application of the above detection method in detection of trace levofloxacin in food with an aqueous heterogeneous system, specifically, the food is detected as a complex matrix by the method provided in the first aspect of the present application, when the product B emits yellow-green phosphorescence after being excited by ultraviolet light, it indicates that the food contains levofloxacin, otherwise it indicates that it does not contain levofloxacin.

[0056] Further, when it is detected that the food contains levofloxacin, the concentration of levofloxacin in the food is determined according to the phosphorescence intensity at a detection wavelength of 500nm-550nm.

[0057] Further, the food is spicy hot pot.

[0058] The embodiments of the present application are described in detail below with reference to the drawings.

[0059] Embodiment 1:

[0060] This embodiment is a pretreatment of a spicy hot pot matrix and a phosphorescence detection after a boron acid assisted levofloxacin enhancement treatment, which is completed according to the following steps:

[0061] Step S1, pretreatment of complex matrix: 1g of spicy hot pot matrix is taken at room temperature, 0.1g of polyethylene oxide (concentration of 10g / L), 0.05g of polymeric ferric sulfate and 0.1g of formic acid (concentration of 1000g / L) are added, the supernatant is taken by centrifugation and neutralized with alkali to obtain extract A.

[0062] Step S2, boron acid assisted levofloxacin enhancement treatment: 1g of boric acid is taken, 1g of extract A is added, 0.005g of cobalt chloride and 0.000005g of sodium iodide are added, and heated at 200℃ for 180min to obtain product B.

[0063] Step S3, phosphorescence detection: the phosphorescence intensity of product B is detected after being excited by 365nm ultraviolet light for 0.5s, as shown in Figure 1 It can be seen that the spicy hot pot matrix without levofloxacin has bright blue background fluorescence under the fluorescence view, and the spicy hot pot matrix with 1mg / mL of levofloxacin can emit yellow phosphorescence after the ultraviolet lamp is turned off, and the intensity of the yellow phosphorescence gradually weakens with the increase of detection time, and almost disappears after 1.25s. As shown in Figure 2 It can be seen that the phosphorescence emission wavelength of levofloxacin in product B is 534nm. Then the detected phosphorescence intensity and the concentration of levofloxacin are linearly fitted, as shown in Figure 3 (It should be noted that, since Figure 3The horizontal axis in the figure uses a logarithmic axis, so that the fitting curve is in exponential form, which actually satisfies a linear relationship. It can be found that the detection method of the embodiment has linearity in the levofloxacin concentration range of 0.001 mg / mL to 1 mg / mL, and satisfies the relationship: y = 14655.43x + 232859.79, x is the levofloxacin concentration, y is the phosphorescence intensity, the fitting degree R 2 = 0.999, and the detection limit of the method of the embodiment is 0.0004 mg / mL.

[0064] The principle of the embodiment is as follows: Figure 4 In the figure, a, b, and c respectively show the influence of the concentrations of various purifying agents (i.e., demulsifier-polyethylene oxide, flocculant-polyferric sulfate, and formic acid) used in step S1 on the purification effect of the spicy soup base (reflected by the relationship between the absorbance / turbidity of the spicy soup base), and good purification effect can be achieved by the synergistic use of purifying agents for different purposes. In terms of the detection method, cobalt ions act as Lewis acids to catalyze the reaction of boric acid with levofloxacin, as shown in Figure 5 , wherein the levofloxacin content is 0.1 mg / mL; and iodine ions enhance phosphorescence through heavy atom effect, as shown in Figure 6 , wherein the levofloxacin content is 0.1 mg / mL, and after the addition of sodium iodide, the phosphorescence intensity of levofloxacin is enhanced compared to when sodium iodide is not added. See Figure 7 , by comparing the 1H NMR spectra before and after the reaction in step S2, wherein the green line is levofloxacin before the reaction in step S2, and the red line is levofloxacin after the reaction with boric acid, it can be seen that the chemical shifts of 3.45, 2.67, and 2.42 belong to the chemical shifts of hydrogens on the diazine ring and the methyl groups linked thereto change, and the chemical shifts of other hydrogens do not change. Therefore, the skeleton structure of levofloxacin is relatively complete, and the chemical shifts of the diazine ring and the methyl groups thereon are greatly affected. It can be seen that boric acid interacts with the part that can freely rotate, making it stable, thereby reducing the non-radiative transition energy loss caused by molecular vibration and rotation. See Figure 8 , by comparing the infrared spectra before and after the reaction in step S2, wherein the solid line is the infrared spectrum of levofloxacin, it can be seen that there is OH absorption of carboxyl at 3264 cm -1 , and this absorption almost disappears after the reaction. Therefore, it can be known that the carboxyl group belonging to levofloxacin disappears due to the reaction with boric acid. And through the scanning electron microscope image of the reaction product Figure 9 , it can be seen that its surface is smooth, with only some cracks, and does not have nanostructures such as carbon dots. Therefore, when the concentration is low, levofloxacin will not further react to form other phosphorescent substances, which is the basis for quantitatively detecting the concentration of levofloxacin.

[0065] Example 2:

[0066] The embodiment is to pretreat the spicy hot pot matrix and perform phosphorescence detection after levofloxacin enhancement treatment based on boric acid assistance, which is completed according to the following steps:

[0067] Step S1, pretreatment of complex matrix: take 1g of spicy hot pot matrix, add 0.1g of polyethylene oxide (concentration of 0.01g / L), 0.02g of polymeric ferric sulfate and 0.1g of hydrochloric acid (concentration of 500g / L), centrifuge to take supernatant and neutralize with alkali to obtain extract solution A.

[0068] Step S2, levofloxacin enhancement treatment based on boric acid assistance: take 1g of boric acid, add 50g of extract solution A, add 0.0025g of cobalt sulfate and 0.0025g of potassium iodide, heat at 225℃ for 150min to obtain product B.

[0069] Step S3, phosphorescence detection: after product B is excited by 370nm ultraviolet light, the phosphorescence intensity after 2.5s is detected.

[0070] Example 3:

[0071] The embodiment is to pretreat the spicy hot pot matrix and perform phosphorescence detection after levofloxacin enhancement treatment based on boric acid assistance, which is completed according to the following steps:

[0072] Step S1, pretreatment of complex matrix: take 1g of spicy hot pot matrix, add 0.1g of polyethylene oxide (concentration of 0.1g / L), 0.01g of polymeric aluminum sulfate and 0.2mL of acetic acid (concentration of 1000g / L), centrifuge to take supernatant and neutralize with alkali to obtain extract solution A.

[0073] Step S2, levofloxacin enhancement treatment based on boric acid assistance: take 1g of boric acid, add 0.5g of extract solution A, add 0.005g of cobalt nitrate and 0.005g of sodium iodide, heat at 300℃ for 5min to obtain product B.

[0074] Step S3, phosphorescence detection: after product B is excited by 400nm ultraviolet light, the phosphorescence intensity after 0.1s is detected.

[0075] Example 4:

[0076] The embodiment is to pretreat the spicy hot pot matrix and perform phosphorescence detection after levofloxacin enhancement treatment based on boric acid assistance, which is completed according to the following steps:

[0077] Step S1, pretreatment of complex matrix: take 1g of spicy hot pot matrix, add 0.1g of polyethylene oxide (concentration of 1g / L), 0.1g of polymeric aluminum sulfate and 0.1g of formic acid (concentration of 1g / L), centrifuge to take supernatant and neutralize with alkali to obtain extract solution A.

[0078] Step S2, levofloxacin enhancement treatment based on boric acid assistance: take 1 g of boric acid, add 100 g of extract liquid A, add 0.000005 g of cobalt sulfate and 0.000005 g of potassium iodide, heat at 150°C for 300 min to obtain product B.

[0079] Step S3, phosphorescence detection: after product B is excited by 340 nm ultraviolet light, the phosphorescence intensity after 5 s is detected.

[0080] Example 5:

[0081] This embodiment is to perform phosphorescence detection on the hot and spicy soup matrix after pretreatment and levofloxacin enhancement treatment based on boric acid assistance, which is completed according to the following steps:

[0082] Step S1, pretreatment of complex matrix: take 1 g of hot and spicy soup matrix, add 0.1 g of polyethylene oxide (concentration of 5 g / L), 0.03 g of polymeric ferric sulfate and 0.1 g of acetic acid (concentration of 20 g / L), centrifuge to obtain the supernatant and neutralize with alkali to obtain extract liquid A.

[0083] Step S2, levofloxacin enhancement treatment based on boric acid assistance: take 1 g of boric acid, add 25 g of extract liquid A, add 0.001 g of cobalt chloride and 0.001 g of sodium iodide, heat at 275°C for 75 min to obtain product B.

[0084] Step S3, phosphorescence detection: after product B is excited by 380 nm ultraviolet light, the phosphorescence intensity after 1.5 s is detected.

[0085] Reference Figure 10 , the experimental data for single factor optimization of each raw material parameter in the detection method of the present application. Wherein a indicates the influence of the mass ratio of boric acid to iodine salt on the relative phosphorescence intensity of the product, it can be seen that the product has strong phosphorescence in the range of 0.005‰-5‰, and is higher than the group without adding iodine salt. B indicates the influence of the mass ratio of boric acid to cobalt salt on the relative phosphorescence intensity of the product, it can be seen that the product has strong phosphorescence in the range of 0.005‰-5‰, and is higher than the group without adding cobalt salt. C indicates the influence of reaction temperature on the relative phosphorescence intensity of the product, it can be seen that the product has strong phosphorescence in the range of 150°C-300°C. D indicates the influence of the mass ratio of boric acid to extract liquid on the relative phosphorescence intensity of the product, it can be seen that it has good effect in the range of 0.5-100.

[0086] The technical scheme of the present application is not limited to the specific embodiments listed above, but also includes various applications of boric acid mixed with iodine salt and cobalt salt for micro-levofloxacin detection.

[0087] In summary, the present application can be applied to quantitative or qualitative detection of trace levofloxacin in complex matrix extraction solution, and has high detection sensitivity, convenient operation, obvious phenomenon, and is beneficial to rapid detection.

[0088] The embodiments of the present application have been described in detail, but the present application is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present application.

Claims

1. A method for the phosphorimetric detection of levofloxacin in a complex matrix, characterized in that, The complex matrix is an aqueous heterogeneous system, and the phosphorescence detection method comprises: An emulsion breaker A, a flocculant B and an acid C are added into the complex matrix, the supernatant is obtained by centrifugation, and the supernatant is neutralized by an alkali to obtain an extract liquid A; the emulsion breaker A is selected from polyethylene oxide, and the concentration of the emulsion breaker A is 0.01 g / L to 10 g / L; the flocculant B is selected from any one of polymeric ferric sulfate and polymeric aluminum sulfate or a mixture of the two; the concentration of the acid C is 1 g / L to 1000 g / L; and the mass ratio of the complex matrix, the emulsion breaker A, the flocculant B and the acid C is 1:0.1:0.01-0.2:0.1; Boric acid is mixed with the extract liquid A, a catalyst D and a catalyst E are added into the mixture, and the mixture is heated to obtain a product B; the catalyst D is selected from cobalt salts, and the catalyst E is selected from iodine salts; and the mass ratio of the boric acid, the extract liquid A, the catalyst D and the catalyst E is 1:0.5-100:0.005‰-5‰:0.005‰-5‰; The product B is excited by ultraviolet light, and phosphorescence detection is performed to obtain the detection result of levofloxacin in the complex matrix.

2. The phosphorescence detection method according to claim 1, wherein, The acid C is selected from any one or a mixture of more than one of formic acid, acetic acid and hydrochloric acid.

3. The phosphorescence detection method according to claim 1, wherein, The catalyst D is selected from any one or a mixture of more than one of cobalt chloride, cobalt nitrate and cobalt sulfate.

4. The phosphorescence detection method according to claim 1, wherein, The catalyst E is selected from any one or a mixture of more than one of sodium iodide and potassium iodide.

5. The phosphorescence detection method according to claim 1, wherein, The temperature used in the heating is 150°C to 300°C.

6. The phosphorescence detection method according to claim 1, wherein, The excitation light wavelength used in the ultraviolet excitation of the product B is 340 nm to 400 nm, and the detection time of the phosphorescence is 0.1 s to 5 s.

7. The phosphorescence detection method according to claim 1, wherein The phosphorescence detection method further comprises: The linear relationship between the phosphorescence intensity and the concentration of levofloxacin is used to quantitatively or qualitatively detect the concentration of levofloxacin in the complex matrix; when used for quantitative detection, the linear detection range of the levofloxacin is 0.001 mg / mL to 1 mg / mL, and the detection limit is 0.0004 mg / mL.

8. The phosphorescence detection method according to claim 7, wherein, When the complex matrix contains levofloxacin, the phosphorescence is yellow-green phosphorescence or the phosphorescence intensity at a detection wavelength of 500 nm to 550 nm.

9. The phosphorescence detection method according to any one of claims 1 to 8 in the detection of trace levofloxacin in food with an aqueous heterogeneous system.

10. Use according to claim 9, characterized in that, The food is spicy hot pot.

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