Bisphenol S fluorescence detection method based on polydopamine nanoparticles and pH regulation

Abstract

The invention discloses a bisphenol S fluorescence detection method based on polydopamine nanoparticles and pH regulation and control, and belongs to the technical field of analysis and detection. The method for detecting bisphenol S based on pH regulation and control comprises the following steps: mixing a sample to be detected with water and a phosphate buffer solution with the pH value of 9.0, uniformly oscillating, determining the fluorescence spectrum of the sample under the excitation of 310 nm, and calculating the content of bisphenol S in the sample to be detected according to a standard curve at the fluorescence intensity of 460 nm, fluorescence emission and characteristic absorption of bisphenol S are enhanced through a simple pH regulation and control method, high-sensitivity detection of bisphenol S is realized, and the method does not need to prepare a composite material with a complicated process, has the advantages of sensitivity, rapidness, simplicity and convenience, and has relatively good detection capability on bisphenol S in an actual sample.

Description

Technical Field

[0001] The invention relates to a bisphenol S fluorescence detection method based on polydopamine nanoparticles and pH regulation, belonging to the technical field of analysis and detection. Background Art

[0002] After bisphenol A was identified as an endocrine disruptor harmful to humans and subsequently restricted or banned from use in products such as food packaging, baby bottles, and thermal paper, various structural analogs of bisphenol A, including bisphenol S, bisphenol F, and tetrabromobisphenol A, gradually replaced bisphenol A in industrial production to avoid threats to consumer health and reduce environmental impact. However, as these substitutes became widely used and research on them deepened, multiple studies have shown that bisphenol S has similar hormonal activity, cytotoxicity, neurotoxicity, and reproductive and developmental toxicity to bisphenol A. Furthermore, bisphenol S has a longer biological half-life and stronger resistance to biodegradation, allowing it to enter the human body through multiple routes of exposure and accumulate, ultimately leading to serious hazards such as obesity, immune dysfunction, and reproductive defects.

[0003] Currently available detection technologies for BPS include liquid chromatography and its associated methods, ultraviolet spectrophotometry, electrochemical methods, chemiluminescence, and fluorescence spectroscopy. Liquid chromatography-tandem mass spectrometry (LC-MS / MS) is the national standard for determining the migration of BPS in food, food contact materials, and products, with limits of detection and quantification as low as 0.03 μg / kg and 0.10 μg / kg, respectively. While LC-MS / MS offers exceptional specificity and sensitivity, it also requires expensive instrumentation and specialized operators, cumbersome sample pretreatment procedures, and long analysis times. Consequently, a series of new technologies have been proposed for the accurate and rapid detection of BPS, such as electrochemical sensors modified with glassy carbon electrodes using various materials, and fluorescent sensors combining metal-organic frameworks, molybdenum disulfide nanosheets, and gold nanoparticles with fluorescent materials. However, the electrode modification of most electrochemical sensors requires the use of at least two materials to achieve functional complementarity. Most fluorescent sensors with outstanding performance also use nucleic acid aptamers to improve the specific recognition ability of bisphenol S. The use of composite materials and biomaterials has also increased the complexity and cost of the detection method to a certain extent. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a method for detecting bisphenol S using polydopamine nanoparticles (DPA-PDs) as a fluorescent probe and supplemented by pH control. The method uses dopamine hydrochloride as a precursor to prepare DPA-PDs through a simple one-step hydrothermal method; after bisphenol S is deprotonated in an alkaline environment, its fluorescence emission and characteristic absorption band are enhanced, and the red-shifted characteristic absorption band overlaps with the excitation spectrum and emission spectrum of DPA-PDs. Therefore, in an alkaline environment, as the concentration of bisphenol S increases, the 310nm fluorescence emission of DPA-PDs will be quenched due to the inner filter effect, while the 460nm fluorescence emission of bisphenol S will gradually increase. Bisphenol S is detected with high sensitivity using the 460nm fluorescence intensity or the ratio of the 460nm fluorescence intensity to the 310nm fluorescence intensity. This method is simple to operate and has high sensitivity and accuracy.

[0005] In order to achieve the above objectives, the technical solutions provided are as follows:

[0006] The first object of the present invention is to provide a method for detecting bisphenol S based on pH control, the method comprising the following steps:

[0007] The sample to be tested was mixed with water and a phosphate buffer solution of pH=9.0 and shaken to be uniform. The fluorescence spectrum of the sample under 310nm excitation was measured. The content of bisphenol S in the sample to be tested was calculated based on the fluorescence intensity at 460nm and the standard curve.

[0008] In one embodiment, the concentration of the phosphate buffer is 0.1 to 0.5 mol / L.

[0009] In one embodiment, the volume ratio of the sample to be tested to water and phosphate buffer is 1:1 to 2:7.

[0010] In one embodiment, the standard curve is established by taking a series of concentrations of bisphenol S, mixing them with water and phosphate buffer solution and shaking them evenly, measuring the fluorescence spectrum of each sample under 310 nm excitation; and constructing a standard curve with the fluorescence intensity of bisphenol S at 460 nm as the vertical axis and the concentration of bisphenol S as the horizontal axis.

[0011] A second object of the present invention is to provide a method for fluorescence detection of bisphenol S based on polydopamine nanoparticles and pH regulation, the method comprising the following steps:

[0012] (1) Construction of quantitative relationship model

[0013] A polydopamine nanoparticle (DPA)-PDs fluorescent probe system was oscillated with a series of bisphenol S solutions of known concentrations to obtain standard samples. The emission spectra of each standard sample under 290 nm excitation were measured. A quantitative relationship model was established with bisphenol S concentration as the horizontal axis and fluorescence intensity at 460 nm or the ratio of fluorescence intensity at 460 nm to fluorescence intensity at 310 nm as the vertical axis.

[0014] (2) Determination of bisphenol S content in the sample

[0015] The polydopamine nanoparticle DPA-PDs fluorescent probe system is mixed with the test solution and shaken to obtain a test sample. The emission spectrum of the test sample under 290 nm excitation is then measured. The content of bisphenol S in the test sample is calculated based on the fluorescence intensity at 460 nm or the ratio of the fluorescence intensity at 460 nm to the fluorescence intensity at 310 nm and the quantitative relationship model constructed in step (1).

[0016] In one embodiment, the preparation of the DPA-PDs fluorescent probe system includes the following:

[0017] Dopamine hydrochloride is dissolved in water and then transferred to a high-pressure reactor for hydrothermal reaction to obtain a crude product; the crude product is filtered through a filter membrane to obtain a DPA-PDs solution; the DPA-PDs solution is evenly mixed with water and an alkaline buffer solution to obtain a DPA-PDs fluorescent probe system.

[0018] In one embodiment, the mass volume ratio of the dopamine hydrochloride to water is 0.1:10-30 g mL.

[0019] In one embodiment, the hydrothermal reaction temperature is 180-200° C., and the time is 8-12 hours.

[0020] In one embodiment, the alkaline buffer solution is a phosphate buffer solution adjusted with sodium hydroxide, with a pH value greater than 7, a concentration of 0.1-0.2 mol / L, and a volume accounting for 50-90% of the total volume of the DPA-PDs fluorescent probe system; preferably, the pH value is 9.

[0021] In one embodiment, the concentration of the DPA-PDs solution is defined as 1 unit when the absorption value of the DPA-PDs solution at 284 nm in the UV-visible absorption spectrum is 0.700.

[0022] In one embodiment, the concentration of DPA-PDs in the DPA-PDs fluorescent probe system in step (1) and step (2) is 0.1-0.5 units; the DPA-PDs fluorescent probe system accounts for 90% of the total volume of the sample.

[0023] In one embodiment, the DPA-PDs fluorescent probe system includes a DPA-PDs solution, water, and an alkaline buffer solution in a volume ratio of 1 to 5:1:7.

[0024] The third object of the present invention is to provide an application of the above method in the detection of bisphenol S.

[0025] Beneficial effects:

[0026] (1) The present invention uses dopamine hydrochloride as a precursor to prepare polydopamine nanoparticles (DPA-PDs) through a hydrothermal method, and combines a simple pH control method to enhance the fluorescence emission and characteristic absorption of bisphenol S. In an alkaline environment, the fluorescence emission of DPA-PDs will be quenched by bisphenol S due to the inner filter effect, while the fluorescence emission of bisphenol S gradually increases with increasing concentration. The detection limit of the single-signal sensing model constructed based on the intrinsic fluorescence of bisphenol S is as low as 0.075μmol / L, and the detection limit of the ratio-type fluorescence sensing model constructed based on the ratio of the emission intensity of DPA-PDs and bisphenol S is as low as 0.257μmol / L.

[0027] (2) The detection method established in the present invention does not require the preparation of composite materials with complicated processes, has good selectivity for bisphenol S among a series of bisphenol compounds, and has the advantages of being sensitive, fast and simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Spectral characteristic diagrams of polydopamine nanoparticles prepared in Example 1 of the present invention; (A) Three-dimensional fluorescence spectrum of polydopamine nanoparticles; (B) UV-visible absorption spectrum, excitation spectrum (λem=310nm) and emission spectrum (λex=280nm) of polydopamine nanoparticles;

[0029] Figure 2 This is a single-signal sensing model constructed based on the intrinsic fluorescence of bisphenol S in Example 2 of the present invention; (A) Emission spectra of bisphenol S at different concentrations; (B) Relationship curve between fluorescence intensity at 460 nm and bisphenol S concentration (0-700 μmol / L); (C) Relationship curve between fluorescence intensity at 460 nm and bisphenol S concentration (0-100 μmol / L), and linear fitting results in the range of 0.5-100 μmol / L; (D) Relationship curve between fluorescence intensity at 460 nm and bisphenol S concentration (0-10 μmol / L);

[0030] Figure 3Ratio-type fluorescence sensing model constructed for Example 3 of the present invention; (A) Emission spectra of the system at different concentrations of bisphenol S; (B) Relationship curve between fluorescence quenching rate at 310 nm and bisphenol S concentration (0-500 μmol / L); (C) Relationship curve between fluorescence enhancement at 460 nm and bisphenol S concentration (0-500 μmol / L); (D) Relationship curve between the ratio of emission intensity at 460 nm and 310 nm and bisphenol S concentration (0-500 μmol / L); (E) Relationship curve between fluorescence enhancement at 460 nm and bisphenol S concentration (F) Relationship curve between the emission intensity ratio at 460 nm and 310 nm and the bisphenol S concentration (0-100 μmol / L), and the linear fitting results in the range of 10-100 μmol / L; (G) Relationship curve between the emission intensity ratio at 460 nm and 310 nm and the bisphenol S concentration (0-10 μmol / L), and the linear fitting results in the range of 1-10 μmol / L;

[0031] Figure 4 Spectral characteristic diagrams of Example 4 of the present invention in different pH environments; (A) Fluorescence emission spectra of bisphenol S under excitation at the corresponding optimal excitation wavelength in different pH environments; (B) UV-visible absorption spectra of bisphenol S in different pH environments; (C) Relationship curve between the peak wavelength of the characteristic absorption peak of bisphenol S and pH value; (D) Relationship curve between the absorbance value of the characteristic absorption peak of bisphenol S and pH value; (E) Fluorescence emission spectra of polydopamine nanoparticles under excitation at 280 nm in different pH environments (the inset shows the relationship between the fluorescence intensity at 310 nm and pH value); (F) UV-visible absorption spectra of polydopamine nanoparticles in different pH environments;

[0032] Figure 5 The data analysis diagrams under different detection conditions of the present invention are as follows; (A) Emission spectra of polydopamine nanoparticles, bisphenol S, and a mixture of polydopamine nanoparticles and bisphenol S under 290 nm excitation; (B) UV-visible absorption spectra of polydopamine nanoparticles, bisphenol S, and a mixture of polydopamine nanoparticles and bisphenol S; (C) UV-visible absorption spectrum of bisphenol S, excitation spectrum, and emission spectrum of polydopamine nanoparticles; (D) Time-resolved fluorescence spectra of polydopamine nanoparticles before and after the addition of bisphenol S;

[0033] Figure 6Graph showing the selectivity and anti-interference ability of Example 5 of the present invention; (A) fluorescence quenching rate at 310 nm, (B) fluorescence enhancement at 460 nm, and (C) ratio of emission intensities at 460 nm to 310 nm when bisphenol S and a potential interfering substance are added separately; (D) fluorescence quenching rate at 310 nm, (E) fluorescence enhancement at 460 nm, and (F) ratio of emission intensities at 460 nm to 310 nm of the system when bisphenol S and a potential interfering substance are added simultaneously.

[0034] Figure 7 Graphs of the linear model established for the Sprite sample according to Example 6 of the present invention; (A) a linear model established for the degree of fluorescence enhancement at 460 nm; and (B) a linear model established for the ratio of emission intensities at 460 nm and 310 nm. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. The following specific embodiments further describe the present invention.

[0036] Example 1

[0037] Preparation of polydopamine nanoparticles DPA-PDs includes the following steps:

[0038] 0.1 g of dopamine hydrochloride was dissolved in 10 mL of deionized water, and the resulting transparent solution was transferred to a 15 mL polytetrafluoroethylene-lined autoclave and heated at 200°C for 8 h to obtain a crude product; after naturally cooling to room temperature, the crude product was filtered using a 0.22 μm filter membrane, and the filtered DPA-PDs solution was stored at 4°C for future use.

[0039] The concentration of DPA-PDs solution corresponding to an absorption value of 0.700 at 284 nm in the UV-visible absorption spectrum was defined as 1 unit.

[0040] like Figure 1 As shown in Figure 3, the UV-visible absorption spectrum of DPA-PDs exhibits characteristic absorption peaks at 220nm and 280nm. The three-dimensional fluorescence spectrum of DPA-PDs has only one emission center, and DPA-PDs have a 310nm fluorescence emission that is independent of the excitation wavelength, corresponding to an optimal excitation wavelength of 280nm.

[0041] Example 2

[0042] A method for detecting bisphenol S based on pH regulation, the method comprising the following steps:

[0043] (1) Construction of standard curve

[0044] 200 μL of deionized water and 700 μL of phosphate buffer solution (0.1 mol / L, pH = 9.0) were mixed and shaken evenly, and then 100 μL of bisphenol S solution of different concentrations (1, 3, 5, 7, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000 μmol / L) were added respectively. For the blank control group, an equal amount of deionized water was added and shaken again. The fluorescence spectrum of each sample under 310 nm excitation was measured; a standard curve was constructed with the fluorescence intensity of bisphenol S at 460 nm as the ordinate and the concentration of bisphenol S as the abscissa;

[0045] (2) Detection of bisphenol S in the sample to be tested

[0046] Take 100 μL of the sample to be tested, mix it with 200 μL of deionized water and 700 μL of phosphate buffer solution (0.1 mol / L, pH = 9.0) and shake it evenly. Measure the fluorescence spectrum of the sample under 310 nm excitation, and calculate the content of bisphenol S in the sample to be tested based on the standard curve constructed in step (1).

[0047] The results are as follows Figure 2 As shown, the intrinsic fluorescence intensity of bisphenol S at 460 nm was positively correlated with the concentration of bisphenol S in the range of 0-200 μmol / L ( Figure 2 B), and the two have a higher linear correlation in the range of 0-100 μmol / L; the results of linear fitting show that under 310 nm excitation, the fluorescence intensity of bisphenol S at 460 nm is linearly correlated with the concentration of bisphenol S in the range of 0.5-100 μmol / L (R 2 0.9950), the detection limit was calculated to be 0.075 μmol / L; however, when the concentration of bisphenol S was greater than 200 μmol / L and further increased, the influence of the inner filter effect gradually increased, and the fluorescence intensity at 460 nm no longer maintained a monotonic increase ( Figure 2 B).

[0048] Example 3

[0049] A method for detecting bisphenol S combining polydopamine nanoparticles and pH regulation, the method comprising the following steps:

[0050] (1) Construction of standard curve

[0051] 100 μL DPA-PDs solution (concentration of 1 unit), 100 μL deionized water and 700 μL phosphate buffer solution (0.1 mol / L, pH = 9.0) were mixed and shaken evenly, and then 100 μL of bisphenol S solution with different concentrations (1, 3, 5, 7, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000 μmol / L) were added respectively. The blank control group was added with an equal amount of deionized water and shaken again; the fluorescence spectrum of each sample under 290 nm excitation was measured; the concentration of bisphenol S solution was used as the horizontal axis and I was used as the horizontal axis. 460 / I 310 The ratio is used as the ordinate to construct a standard curve;

[0052] (2) Detection of bisphenol S in the sample to be tested

[0053] Take 100 μL of the sample to be tested, mix it with 100 μL of DPA-PDs solution, 100 μL of deionized water and 700 μL of phosphate buffer solution (0.1 mol / L, pH = 9.0) and shake it evenly. Measure the fluorescence spectrum of the sample under excitation at 290 nm, and calculate the content of bisphenol S in the sample to be tested based on the standard curve constructed in step (1).

[0054] The results are as follows Figure 3 As shown in Figure 2, as the concentration of bisphenol S increases, the fluorescence emission at 310 nm attributed to DPA-PDs is gradually quenched, while the emission peak at 460 nm attributed to the intrinsic fluorescence of bisphenol S is gradually enhanced ( Figure 3 A). For the fluorescence quenching rate at 310 nm, when the concentration of bisphenol S is greater than or equal to 200 μmol / L, the quenching rate approaches saturation; while in the range of 0-20 μmol / L, the regularity between the fluorescence quenching rate caused by bisphenol S and the bisphenol S concentration is poor, which ultimately makes it difficult to find a good linear correlation (R) in the relationship curve between the fluorescence quenching rate at 310 nm and the bisphenol S concentration. 2 close to or greater than 0.99).

[0055] Although there is no significant linear correlation between the quenching rate of the emission peak at 310 nm and the concentration of bisphenol S, the ratio of the emission intensity at 460 nm to that at 310 nm (I 460 / I 310 ) and bisphenol S concentration showed a two-stage linear correlation within the range of less than or equal to 100 μmol / L. Figure 3 As shown in F and 3G, I 460 / I 310It was linearly correlated with the bisphenol S concentration in the ranges of 1-10 μmol / L and 10-100 μmol / L, and the detection limit was calculated to be 0.257 μmol / L.

[0056] In addition, although the single-signal sensing model constructed based on the intrinsic fluorescence of bisphenol S has a lower detection limit (Example 2), the ratiometric fluorescence sensing model constructed by introducing DPA-PDs (Example 3) has a lower detection limit. 460 / I 310 ) can avoid the irregular changes in fluorescence intensity at 460nm caused by the inner filter effect when the concentration of bisphenol S is greater than 200μmol / L, and has a better qualitative discrimination effect for high concentration ranges (such as Figure 3 C or Figure 2 B and Figure 3 D).

[0057] Example 4 pH Condition Optimization

[0058] Referring to the method of Example 2, 200 μL of deionized water, 100 μL of bisphenol S solution, or 100 μL of DPA-PDs solution were respectively mixed with 700 μL of phosphate buffer solution and shaken evenly, wherein the concentration of the bisphenol S solution was 5 mmol / L, the concentration of the DPA-PDs solution was 1 unit, the concentration of the phosphate buffer solution was 0.1 mol / L, and the pH values ​​were 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, and 12.0, respectively; the fluorescence spectrum of each sample under excitation at 290 nm was measured.

[0059] The results are as follows Figure 4 As shown in Figure B, as the pH of the system increases, the two characteristic absorption peaks of bisphenol S have a consistent change trend. The two characteristic absorption peaks originally located at 234nm (characteristic absorption peak 1) and 259nm (characteristic absorption peak 2) will red-shift to around 260nm and 292nm respectively, and the intensity of the absorption peak will first decrease and then increase. The red-shift of characteristic absorption peak 1 mainly occurs in the process of increasing pH from 7.0 to 9.0, and the pH inflection point of the absorption value change is 8.0; while the red-shift of characteristic absorption peak 2 is completed in the process of increasing pH from 6.0 to 8.0, and the pH inflection point of the absorption value change is 7.0. For the fluorescence characteristics ( Figure 4 A), when the pH of the system is less than 7.0, the emission peak of bisphenol S is located at 500nm; as the pH increases to 10.0, the emission peak gradually blue-shifts and the fluorescence emission intensity significantly increases, corresponding to the optimal excitation wavelength changing from 280nm to 310nm; when the pH further increases, the emission peak continues to blue-shift to 394nm and the half-height width significantly decreases, and the intensity further increases. It is speculated that the unique response of the spectral characteristics of bisphenol S to pH is related to its deprotonation process in an alkaline environment. For DPA-PDs, Figure 4E shows that the pH of the system only affects the fluorescence emission intensity of DPA-PDs without affecting the position of its emission peak. The fluorescence emission intensity of DPA-PDs gradually decreases with increasing pH and is almost completely quenched when the pH is greater than or equal to 11.0. When the pH is greater than 8.0, the characteristic absorption peak of DPA-PDs at 280nm will undergo an enhanced red shift with increasing pH, and a new broad absorption band at 434nm will be added to its absorption spectrum when the pH is greater than or equal to 11.0 ( Figure 4 F). Taking into account the effect of pH control on the spectral characteristics of DPA-PDs and bisphenol S, a pH of 9.0 was selected as the environment for bisphenol S detection. This fully enhances the intrinsic fluorescence and characteristic absorption of bisphenol S while preventing the complete quenching of the fluorescence emission of DPA-PDs under strong alkaline conditions.

[0060] At pH 9.0, bisphenol S can significantly quench the fluorescence emission of DPA-PDs at 310 nm and generate its intrinsic fluorescence emission peak at 460 nm ( Figure 5 A). Figure 5 The UV-visible absorption spectrum shown in B indicates that the absorption spectrum of the mixture of DPA-PDs and bisphenol S (red line) is basically consistent with the superposition spectrum of the absorption spectra of the two monomers (green line), that is, no non-fluorescent ground state complex is produced in the DPA-PDs and bisphenol S mixture system, eliminating the existence of a static quenching mechanism. By comparing the spectral characteristics of bisphenol S and DPA-PDs, it can be found that the characteristic absorption peak 2 of bisphenol S at 292nm overlaps with the excitation spectrum and emission spectrum of DPA-PDs ( Figure 5 C), which is also close to the selected excitation light wavelength (290nm), so we can preliminarily speculate that there are two fluorescence quenching mechanisms characterized by the overlap of donor and acceptor spectra: inner filter effect and resonance energy transfer. Figure 5 The time-resolved fluorescence spectra (D) indicate that the fluorescence lifetime of DPA-PDs remains essentially unchanged before and after the addition of bisphenol S. Therefore, the contribution of resonance energy transfer to the fluorescence quenching of DPA-PDs is ruled out. It is determined that bisphenol S quenches DPA-PDs fluorescence primarily through the inner filter effect, competing with DPA-PDs for both excitation light and fluorescence emission.

[0061] Example 5 Selectivity and Anti-interference Ability

[0062] For potential interferences, in addition to the four bisphenol compounds of bisphenol A, bisphenol AF, bisphenol b, and bisphenol F, two phenol compounds of phenol and catechol as well as common ions in water (Na + , K + , Ca 2+ Mg 2+ 、Zn2+ 、SO4 2- ).

[0063] In the selectivity experiment, referring to the method of Example 3, 100 μL of DPA-PDs solution (concentration of 1 unit), 100 μL of deionized water, 100 μL of bisphenol S solution or interferor solution and 700 μL of phosphate buffer solution (0.1 mol / L, pH 9) were mixed and shaken until uniform, wherein the concentration of the bisphenol S solution was 100 μmol / L, the concentration of the organic interferor solution was 500 μmol / L, and the concentration of the ionic interferor solution was 5 mmol / L; the fluorescence spectrum of each sample under excitation at 290 nm was measured.

[0064] In the anti-interference ability experiment, referring to the method of Example 3, 100 μL of DPA-PDs solution (concentration of 1 unit), 100 μL of bisphenol S solution, 100 μL of interferor solution and 700 μL of phosphate buffer solution (0.1 mol / L, pH 9) were mixed and shaken evenly, wherein the concentration of bisphenol S solution was 100 μmol / L, the concentration of organic interferor solution was 500 μmol / L, and the concentration of ionic interferor solution was 5 mmol / L; the fluorescence spectrum of each sample under excitation at 290 nm was measured.

[0065] Depend on Figure 6 The results show that it is impossible to achieve specific detection of bisphenol S by relying solely on the fluorescence quenching rate of the emission peak at 310 nm; however, the ratio of the fluorescence enhancement at 460 nm caused by bisphenol S to the emission intensity at 460 nm and 310 nm is significantly higher than that of other potential interferents, even though the concentration of bisphenol S is lower than that of these potential interferents. 2+ With Zn 2+ It can also cause fluorescence enhancement at 460nm, but the corresponding fluorescence enhancement degree is much lower than that of bisphenol S ( Figure 6 B). When these interfering substances coexist with bisphenol S, they do not significantly interfere with the fluorescence enhancement at 460 nm caused by bisphenol S. These results demonstrate that the bisphenol S detection method proposed in this invention based on DPA-PDs and pH regulation exhibits good selectivity and anti-interference ability for bisphenol S.

[0066] Example 6

[0067] The method for detecting bisphenol S in actual samples based on DPA-PDs and pH control specifically includes the following steps:

[0068] Bottled drinking water, Sprite, plastic bottles, plastic cups, and plastic food packaging bags were selected as actual samples for the experiment. Bottled drinking water and Sprite did not require pretreatment. 0.1g of each of the three plastic products—the plastic bottle, plastic cup, and plastic food packaging bag—was washed with ultrapure water and allowed to dry. The samples were then placed in a beaker containing 100mL of ultrapure water, covered with tin foil, and heated at 80°C for 1 hour. After cooling to room temperature, the plastic products were removed and used as the actual samples.

[0069] For four real-world samples—bottled drinking water, plastic bottles, plastic cups, and plastic food packaging bags—100 μL of DPA-PDs solution (concentration of 1 unit) was mixed with 100 μL of deionized water and 700 μL of phosphate buffer (0.1 mol / L, pH 9.0) and shaken thoroughly. 100 μL of the actual sample was then added to each sample and shaken again. The spiked samples were obtained by replacing the deionized water with an equal volume of bisphenol S solution. The fluorescence spectra of each sample were measured under 290 nm excitation. The bisphenol S content in the sample was calculated based on the standard curve model constructed in Example 3.

[0070] For the Sprite sample, additional model building is required ( Figure 7 ), 100 μL of DPA-PDs solution (concentration: 1 unit) and 700 μL of phosphate buffer solution (0.1 mol / L, pH = 9.0) were mixed and shaken until uniform. Then, 100 μL of Sprite sample and 100 μL of bisphenol S solution of varying concentrations were added and shaken again until uniform. Fluorescence spectra of each sample were measured under 290 nm excitation, and a standard curve model was constructed according to Example 3.

[0071] The detection results of five actual samples with different spiked concentrations are shown in Tables 1 and 2 respectively based on the linear model between the two parameters: the fluorescence enhancement degree at 460 nm and the ratio of the emission intensity at 460 nm to 310 nm and the bisphenol S concentration.

[0072] Table 1 Detection of bisphenol S in actual samples based on the degree of fluorescence enhancement at 460nm

[0073]

[0074]

[0075] Table 2 Detection of bisphenol S in actual samples based on the ratio of emission intensities at 460 nm and 310 nm

[0076]

[0077] For the fluorescence enhancement model at 460 nm, recoveries ranged from 92.6% to 111%, with relative standard deviations (RSDs) ranging from 2.74% to 22.1%. For the emission intensity ratio model at 460 nm to 310 nm, recoveries ranged from 96.6% to 110%, with RSDs ranging from 1.05% to 11.7%. These results demonstrate the feasibility of both models in real-world samples, but the matrix of the Sprite sample interfered with the stability of the 460 nm fluorescence enhancement model (e.g., the RSD for Sprite reached 22.1% in Table 1, while the RSD for Sprite samples in Table 2 was less than 10%).

[0078] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for detecting bisphenol S based on pH control, characterized in that: The method comprises the following: The sample to be tested was mixed with water and a phosphate buffer solution of pH=9.0 and shaken to be uniform. The fluorescence spectrum of the sample under 310nm excitation was measured. The content of bisphenol S in the sample to be tested was calculated based on the fluorescence intensity at 460nm and the standard curve.

2. The method according to claim 1, characterized in that The volume ratio of the sample to be tested to water and phosphate buffer is 1:1 to 2:

7.

3. A fluorescence detection method for bisphenol S based on polydopamine nanoparticles and pH regulation, characterized in that: The method comprises the following: (1) Construction of quantitative relationship model A polydopamine nanoparticle (DPA)-PDs fluorescent probe system was oscillated with a series of bisphenol S solutions of known concentrations to obtain standard samples. The emission spectra of each standard sample under 290 nm excitation were measured. A quantitative relationship model was established with bisphenol S concentration as the horizontal axis and fluorescence intensity at 460 nm or the ratio of fluorescence intensity at 460 nm to fluorescence intensity at 310 nm as the vertical axis. (2) Determination of bisphenol S content in the sample The polydopamine nanoparticle DPA-PDs fluorescent probe system is mixed with the test solution and shaken to obtain a test sample. The emission spectrum of the test sample under 290 nm excitation is then measured. The content of bisphenol S in the test sample is calculated based on the fluorescence intensity at 460 nm or the ratio of the fluorescence intensity at 460 nm to the fluorescence intensity at 310 nm and the quantitative relationship model constructed in step (1).

4. The method according to claim 3, characterized in that The preparation of the DPA-PDs fluorescent probe system includes the following steps: Dopamine hydrochloride is dissolved in water, and then transferred to a high-pressure reactor for hydrothermal reaction to obtain a crude product; the crude product is filtered through a filter membrane to obtain a DPA-PDs solution; The DPA-PDs solution and the alkaline buffer solution are mixed evenly to obtain the DPA-PDs fluorescent probe system.

5. The method according to claim 4, characterized in that The mass volume ratio of the dopamine hydrochloride to water is 0.1:10-30 g mL.

6. The method according to claim 4, characterized in that The temperature of the hydrothermal reaction is 180-200° C., and the time is 8-12 hours.

7. The method according to claim 4, characterized in that The alkaline buffer solution is a phosphate buffer solution adjusted by sodium hydroxide, with a pH value greater than 7, a concentration of 0.1-0.2 mol / L, and a volume accounting for 50-90% of the total volume of the DPA-PDs fluorescent probe system.

8. The method according to claim 4, characterized in that The concentration of the DPA-PDs solution corresponding to an absorption value of 0.700 at 284 nm in the UV-visible absorption spectrum is defined as 1 unit.

9. The method according to claim 3, characterized in that The DPA-PDs fluorescent probe system accounts for 90% of the total volume of the sample.

10. Use of the method according to any one of claims 1 to 9 in the detection of bisphenol S.

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