Fluorescence / colorimetric sensor, method for detecting Co < 2 + > by using fluorescence / colorimetric sensor and application of fluorescence / colorimetric sensor

Abstract

The invention discloses a fluorescent / colorimetric sensor, a method for detecting Co < 2 + > by using the fluorescent / colorimetric sensor and application of the fluorescent / colorimetric sensor. According to the detection method, Co < 2 + > is oxidized by hydrogen peroxide to generate Co < 3 + > and. OH, HYT is oxidized by Co < 3 + > to generate o-quinone substances, so that Co < 2 + > is regenerated, HYT and o-quinone substances are further oxidized by. OH, a polymerization reaction is initiated, a dimer and an oligomer are generated, and the dimer and the oligomer cannot be subjected to an in-situ fluorescent chromogenic reaction with NR, so that generation of fluorescent chromophores is inhibited. The whole experiment process does not involve expensive reagents and complicated and tedious steps. Experimental results show that the method has high selectivity. Under the optimal experiment condition, the detection limit of Co < 2 + > is 0.323 nM, which is lower than the detection limit based on the fluorescence / colorimetric method reported in the past. More importantly, the method can be used for detecting Co < 2 + > in an actual water sample. In addition, the method widens the detection application range of HYT and NR as precursor micromolecules.

Description

Technical Field

[0001] The present invention relates to the field of fluorescence sensing analysis and detection technology, and in particular to a fluorescence / colorimetric sensor and its application in Co 2+ Detection methods and applications. Background Art

[0002] Cobalt ions (Co 2+ ) As a heavy metal element, it not only inhibits the normal growth and development of plants, but also has an adverse effect on the reproductive system of animals and destroys the ecological balance. For aquatic organisms, excessive cobalt content will cause acute toxicity to aquatic organisms, leading to biological death or physiological dysfunction. Not only that, when cobalt accumulates in the soil, it will cause the soil fertility to decline, and then have an adverse effect on the yield and quality of crops. This series of effects will eventually be transmitted along the food chain, posing a potential threat to human health. From a toxicological point of view, Co 2+ It can cause a variety of health problems, including neurological dysfunction and increase the risk of malignant tumors such as liver cancer and lung cancer. 2+ The wide distribution and severity of pollution require a Co 2+ Detection methods are extremely important for environmental protection and health risk assessment.

[0003] Previous Co 2+ Detection mainly uses atomic absorption spectrophotometry and inductively coupled plasma testing. Although these methods are widely used, they usually require professional technicians to operate, are time-consuming and labor-intensive, and have expensive instruments. In recent years, researchers have developed some novel analytical methods for Co 2+ For example, Han et al. used polyethyleneimine (PEI) as a carbon source to synthesize fluorescent carbon dots (CDs) through a simple one-step hydrothermal route, and CDs were successfully applied to Co 2+ Gore et al. developed a kind of CDs (COF-CDs) that can easily detect Co by UV-visible spectrophotometer or even by naked eyes. 2+ Although these methods have successfully achieved the detection of Co 2+ However, it relies on relatively expensive reagents or materials, which are complicated and tedious to synthesize, greatly limiting its practical application.

[0004] In 2020, Yan's team first discovered that catechol derivatives (such as hydroxytyrosol, dopamine and levodopa) and naphthalene diol (NR) can be prepared into fluorescent chromophores with high quantum yield through a one-step molecular reaction at room temperature. Based on this discovery, the research group developed a sensitive fluorescence / colorimetric detection method for tyrosinase activity determination (CN110407849A). In 2023, the research group based on Cu 2+ and Ag + A selective determination of Cu by triggering the in situ reaction of dopamine (DA) with naphthalene diol (NR) is reported. 2+ and Ag + Inspired by the above work, the present invention found that when there is Co in the solution 2+ When Co 2+ It undergoes redox reaction with H2O2 to generate hydroxyl radicals (·OH) and Co 3+ ,Co 3+ Further reaction with hydroxytyrosol (HYT) generates corresponding o-quinone substances, leading to Co 2+ Regeneration. Subsequently, o-quinone substances and free hydroxytyrosol HYT initiated polymerization under the action of ·OH to generate various dimers and oligomers. Under strong alkaline conditions, the generated dimers and oligomers cannot undergo in situ fluorescence color reaction with NR, inhibiting the formation of fluorescent chromophores. On the contrary, when there is no Co in the system 2+ Under the same conditions, the fluorescence color reaction of HYT and NR is not inhibited by H2O2, and fluorescent chromophores are generated in the solution. Therefore, according to the changes in fluorescence intensity and absorbance, the fluorescence of Co can be easily detected. 2+ Fluorometric / colorimetric assay. Summary of the Invention

[0005] In order to overcome the existing technology of detecting Co 2+ The present invention provides a dual-mode sensing method for detecting Co with simple operation, low cost, high sensitivity, good selectivity and rapid response. 2+ . With the traditional Co 2+ Compared with fluorescence / colorimetric methods, the reagents used in this method are low-cost and commercially available, and do not involve complex material synthesis and chemical modification, so it can be applied to the detection of Co in actual water samples. 2+ Determination of.

[0006] As one aspect of the present invention, the present invention provides a method for 2+ The composition of the fluorescence / colorimetric dual-mode sensing assay comprises the following components: hydroxytyrosol (HYT), H2O2, pH buffer, and water.

[0007] According to the aforementioned composition of the present invention, the pH of the composition is 4.5-6.0, preferably 5.0.

[0008] According to the aforementioned composition of the present invention, the molar ratio of hydroxytyrosol (HYT) to H2O2 is 1:300-1000, preferably 1:500.

[0009] According to the aforementioned composition of the present invention, the pH buffer is a HAc-NaAc buffer.

[0010] As a second aspect of the present invention, the present invention provides a method for detecting Co 2+ The fluorescence / colorimetric dual-mode sensing analysis method comprises the following steps: Step (1) Prepare a solution with pH 4.5 to 6.0 by taking a certain amount of H2O2, hydroxytyrosol (HYT) and Tris buffer, and add different concentrations of Co 2+ React for a while.

[0011] Step (2) Add a certain amount of naphthalene diol (NR) and Na2CO3 buffer solution to the system obtained in step (1), adjust the pH of the system to 8.5-11, continue the reaction for a period of time, and then use a camera to photograph the fluorescence colorimetric effect of the solution under ultraviolet light (365nm) and record the fluorescence spectrum at Ex = 415nm. Use a camera to photograph the colorimetric effect of the solution in a natural light environment and scan and record its ultraviolet absorption spectrum.

[0012] According to the aforementioned method of the present invention, in step (1), the pH is preferably 5.0, the reaction time is 5 min, the reaction temperature is 25°C, the H2O2 concentration is 6 mM, and the hydroxytyrosol (HYT) concentration is 12 μM.

[0013] According to the aforementioned method of the present invention, wherein, the different concentrations of Co in step (1) 2+ The concentration ranges were 0-5 nM and 30-500 nM.

[0014] According to the aforementioned method of the present invention, in step (2), the pH is preferably 11, the concentration of NR is 12 μM, the reaction time is 5 min, and the reaction temperature is 35°C.

[0015] According to the aforementioned method of the present invention, wherein, as Co 2+ With the increase of the concentration, the fluorescence peak of the reaction system at 480nm gradually weakened, and the fluorescence under 365nm ultraviolet light also gradually weakened; at the same time, the ultraviolet absorption value of the reaction at 460nm gradually weakened, and the light yellow color of the solution gradually faded under normal fluorescent light.

[0016] When Co 2+When the concentration is in the range of 0~5nM and 30~500nM, the fluorescence value of the reaction system at 480nm is similar to that of Co 2+ The concentration showed a good linear relationship, and the linear regression equations were y=-92.803 [Co 2+ ]+1198.7(0-5nM, R 2 =0.9817) and y=-1.0769[Co 2+ ]+507.65(30-500nM, R 2 =0.9637), and the method Co is obtained by 3σ / S calculation. 2+ The detection limit was 0.323 nM; When Co 2+ The absorbance of the reaction system at 460nm was similar to that of Co in the concentration range of 0~5nM and 30~300nM. 2+ The concentration showed a good linear relationship, and the linear regression equations were y=-0.0406[Co 2+ ]+0.3705(0-5nM, R 2 =0.9689) and y=-0.0025[Co 2+ ]+0.0939(30-300nM, R 2 =0.9886), and the Co of this method is calculated by 3σ / S 2+ The detection limit was 0.653 nM.

[0017] As a third aspect of the present invention, the present invention also provides a method for applying the aforementioned composition and / or the aforementioned method to Co in tap water or natural water. 2+ The purpose of the test is to filter the water sample with a 0.22 μm filter as a pretreatment and then 2+ The standard solution was mixed and then the fluorescence and UV spectra were scanned to determine the Co 2+ concentration.

[0018] Compared with the prior art, the present invention discloses a novel fluorescence / colorimetric sensor for Co 2+ Detection, this method is based on the oxidation of Co with hydrogen peroxide 2+ Generate Co 3+ and OH, Co 3+ Oxidation of HYT to generate o-quinones leads to Co 2+ Regeneration, further OH oxidation of HYT and o-quinone substances, initiating polymerization reaction, generating dimers and oligomers, dimers and oligomers can not react with NR in situ fluorescence color development, inhibiting the formation of fluorescent chromophores. The entire experimental process does not involve expensive reagents and complicated steps. The experimental results show that this method has high selectivity. Under the optimal experimental conditions, Co2+ The detection limit is 0.323nM, which is lower than the detection limit of previously reported fluorescence / colorimetric methods. More importantly, this method can detect Co in actual water samples. 2+ In addition, this method broadens the application scope of the detection of HYT and NR as precursor small molecules. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is based on the H2O2-HYT-NR fluorescence sensing platform for Co 2+ Schematic diagram of the detection principle.

[0020] Figure 2 Curve (a) Co 2+ +HYT+H2O2+NR, curve (b) HYT+H2O2+NR, curve (c)Co 2+ +HYT+NR, curve (d) fluorescence spectrum A and UV spectrum B of HYT+NR, the insets are pictures under 365nm UV light and natural light. The concentrations of the reagents used are: HYT, 12μM; NR, 12μM; H2O2, 6mM; Co 2+ , 300nM; HAc-NaAc buffer (pH=5.0, 10mM); Na2CO3 buffer (pH=11.0, 200mM).

[0021] Figure 3 Fluorescence spectra of AUR probe (25 mM) in Tris-HCl (5 mM) at pH 9.0. (a) AUR+Co 2+ + H2O2 and (b) AUR+ H2O2(c) AUR+Co 2+ (d) In the presence of AUR, Co 2 + The concentrations of H2O2 and H2O2 were 5 mM and 500 mM, respectively.

[0022] Figure 4 UV-visible absorption spectra of HYT under different conditions. The concentrations of the reagents used are: HYT, 12μM; H2O2, 6mM; Co 2+ , 300nM; HAc-NaAc (pH = 5.0, 10mM).

[0023] Figure 5 Co 2+ High-resolution liquid chromatography-mass spectrometry of the +HYT+ H2O2 reaction system.

[0024] Figure 6A and B are the fluorescence difference spectra of HYT and NR at different concentrations; C, D, and E are the fluorescence difference spectra at different times, temperatures, and pH values. Concentrations: HYT, 12 μM; NR, 12 μM; H2O2, 6 mM; Co 2+ , 300nM; HAc-NaAc (pH=5.0, 10mM); Na2CO3Buffer (pH=11.0).

[0025] Figure 7 A, B, and C are Co 2+ D is the fluorescence difference spectrum of the reaction of +HYT+H2O2 at different pH, time and temperature; D is the fluorescence difference spectrum of hydrogen peroxide at different concentrations. Concentration: HYT, 12μM; NR, 12μM; H2O2, 6mM; Co 2+ , 300nM, HAc-NaAc (pH=5.0, 10mM); Na2CO3 buffer (pH=11.0, 200mM).

[0026] Figure 8 A is Co 2+ Fluorescence spectra at different concentrations, the inset is the solution with Co 2+ Fluorescence changes with increasing concentration; B is F 480 With Co 2+ Working curve when concentration changes; C is Co 2+ UV spectra at different concentrations, the inset is the solution with Co 2+ Color changes with increasing concentration; D is A 460 With Co 2+ Working curves for varying concentrations: HYT, 12 μM; NR, 12 μM; H2O2, 6 mM; HAc-NaAc (pH = 5.0, 10 mM); Na2CO3 buffer (pH = 11.0, 200 mM).

[0027] Figure 9 Sensor for Co 2+ The inset is a colorimetric photograph of the corresponding experimental sample under 365 nm UV light. Interference, 1.5 μM; Co 2+ , 300nM; HYT, 12μM; NR, 12μM; H2O2, 6mM; HAc-NaAc (pH=5.0, 10mM); Na2CO3Buffer (pH=11.0, 200mM).

[0028] Figure 10 Sensor for Co 2+The selectivity of the sample is shown in the inset, which is a colorimetric photograph of the corresponding sample under 365 UV light. Interference, 1.5μM; Co 2+ , 300nM; HYT, 12μM; NR, 12μM; H2O2, 6mM; 10mM HAc-NaAc (pH=5.0, 100mM); Na2CO3Buffer (pH=11.0, 200mM). DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to specific embodiments.

[0030] Reagents and instruments In this invention, cobalt dichloride hexahydrate, hydrogen peroxide, hydroxytyrosol, and metanaphthalene diol were purchased from Sangon Biotechnology Co., Ltd. (Shanghai, China). Mercuric sulfate, ammonium molybdate, silver nitrate, lead acetate, chromium acetate, manganese acetate tetrahydrate, ferric chloride, zinc chloride, ferric chloride, sodium carbonate, anhydrous sodium dihydrogen phosphate, sodium monohydrogen phosphate, and sodium hydrosulfide were purchased from Anaiji Chemical Reagent Network. All aqueous solutions used in the experiments were prepared using sterilized ultrapure water. All other chemical reagents were of analytical grade and were not further purified before use. During the experimental phase, all solutions were prepared using ultrapure water with an impedance exceeding 18.2 MΩ, prepared using a Millipore Milli-Q ultrapure purification system.

[0031] The primary instruments used in this study were a fluorescence spectrophotometer (F-7000), an HH-2 digital constant-temperature water bath, and an MX-S adjustable mixer. Fluorescence measurements were performed at room temperature using the F-7000 fluorescence spectrophotometer. An excitation wavelength of 415 nm was used, and the emission spectrum was scanned from 430 to 600 nm. All images were taken using a smartphone (iPhone) under illumination with a UV analyzer (WFH-204B, Shanghai).

[0032] Example 1 Typical test operation In a 50 μL system, 5 μL 120 mM H2O2, 5 μL 240 μM HYT, 10 μL 100 mM HAc-NaAc (pH 5.0) and different concentrations of Co were added. 2+The reaction was allowed to proceed at 25°C for 5 minutes. Then, 10 μL of 240 μM NR and 10 μL of 200 mM Na₂CO₃ buffer (pH 11.0) were added to the reaction system. After rehydration, the final volume was adjusted to 100 μL. The reaction was continued at 37°C for 10 minutes. The fluorescence colorimetric effect of the solution was then photographed using a mobile phone under UV light (365 nm), and the fluorescence spectrum at Ex = 415 nm was recorded. The colorimetric effect of the solution was also photographed using a mobile phone under natural light, and its UV absorption spectrum was scanned and recorded.

[0033] Example 2 Feasibility Analysis Test In order to verify the feasibility of the proposed dual-mode sensing strategy, the present invention investigated the HYT-NR-H2O2 sensing system for Co 2+ Detection of fluorescence and colorimetric responses. Figure 2 As shown in the figure, under 415nm excitation, the carbonate buffer solution (pH11) containing only HYT and NR showed bright cyan and yellow under UV light and visible light, respectively. At the same time, a strong fluorescence peak and visible absorption peak appeared at 480nm and 460nm, respectively, which is consistent with the characteristic spectrum of Fluo reported in the literature. When H2O2, NR and carbonate buffer were added to the HYT solution in sequence, the fluorescence and absorption signals generated by the HYT-NR reaction did not change significantly; however, under the same conditions, when Co was added to the mixed solution of HYT and H2O2, the fluorescence and absorption signals of NR did not change significantly. 2+ After incubation for 5 minutes, the above solution and NR were mixed in carbonate buffer solution. 2+ The presence of will greatly weaken the fluorescence and absorption intensity of the HYT-NR reaction. At the same time, the solution appears colorless under both UV and visible light. Subsequently, further control experiments were carried out. Figure 2 Curve c shows that when there is Co in the system 2+ , HYT and NR (without H2O2), no obvious fluorescence signal and absorbance decrease were observed, indicating that Co 2+ Does not inhibit the generation of fluorophores, thus eliminating the possibility of Co 2+ The above experiments show that the HYT-NR-H2O2 sensing system is effective for Co 2+ sensitive.

[0034] Example 3 Reaction mechanism verification test The generation of ·OH was verified by fluorescence spectroscopy using Amplex Red reagent (·OH recognition probe). Figure 3 As shown, Co 2+ The mixture with H2O2 resulted in a significant increase in the fluorescence signal at 587 nm, while pure H2O2 or Co 2+The solution showed a weak fluorescence response, indicating that Co 2+ Reacts with H2O2 to generate ·OH. Literature reports that catechols (such as hydroxytyrosol, dopamine and levodopa) can be oxidized by ·OH and initiate polymerization to generate dimers or oligomers. In order to verify the formation of dimers and oligomers, the present invention scanned the UV spectra of different solutions. As shown in Figure 3, when H2O2 or Co was added to the HYT solution, the 2+ When the UV absorption bands obtained by scanning are almost overlapped with the UV absorption bands of pure HYT solution. 2 + The coexistence of H2O2 and HYT showed a significant new absorption peak at a wavelength of 220 nm, indicating that Co 2 + , H2O2 reacted with HYT to generate new substances. HPLC / TOF-MS results confirmed (e.g. Figure 5 As shown in A and B), Co 2 + The products of the +HYT+H2O2 reaction are mainly dimers or oligomers with small molecular weight (300-600Da). 2+ The possible reaction mechanism is Co 2+ First oxidized by H2O2 to generate OH and Co 3+ . Subsequently, Co 3+ Further react with HYT to generate corresponding o-quinone substances and Co 2+ Subsequently, o-quinones initiate polymerization reactions under the action of ·OH, generating various oligomers. In strong alkaline conditions, the generated oligomers cannot undergo in situ fluorescence colorimetric reaction with NR, hindering the formation of fluorescent chromophores.

[0035] Example 4 Reaction Condition Optimization Test In order to obtain the HYT-NR-H2O2 sensor to detect Co 2+ In order to improve the sensitivity of HYT, the present invention first optimized some important experimental conditions that may affect the reaction between HYT and NR, such as the concentration of HYT and NR, reaction time, reaction temperature and reaction pH. 480 In the absence of Co 2+ and existenceCo 2+ As shown in Figure 6A, with the increase of HYT concentration, △F 480 The value gradually increases. When the concentration reaches 12μM, △F 480 The NR concentration was optimized based on the NR concentration. As shown in Figure 6B, it was found that when the NR concentration was 12μM, △F 480The value of reached a maximum value, so 12μM was determined as the optimal concentration of NR. The reaction time, temperature, and pH of HYT and NR were then optimized, as shown in Figure 6C. It can be seen that under strong alkaline conditions, the reaction between HYT and NR is very rapid and tends to be completed after 5 minutes. Therefore, 5 minutes was selected as the optimal reaction time for HYT and NR. By investigating the reaction temperature, when the reaction temperature reached 35℃, △F 480 The value of HYT reaches a peak value (as shown in D in Figure 6). Therefore, 35℃ is the optimal reaction temperature for HYT and NR. Figure 6 As shown in E, when the reaction pH is 3.0-8.5, △F 480 The value is very low, △F at pH 8.5-11.0 480 It gradually increased and reached the maximum value. Therefore, pH = 11.0 was selected as the optimal pH for the reaction of HYT and NR for subsequent experiments.

[0036] According to the experimental principle, Co 2+ Oxidation with H2O2 to generate Co 3+ and OH, Co 3+ Oxidation of HYT generates o-quinones, and ·OH further oxidizes o-quinones to generate dimers and oligomers, which hinder the formation of fluorophores. 2+ The reaction conditions of H2O2 and HYT, such as reaction pH, reaction temperature, reaction time and H2O2 concentration, were investigated. 480 Indicates that there is no Co 2+ and existenceCo 2+ As shown in Figure 7A, when the reaction pH is 5.0, △F 480 Therefore, pH = 5.0 was selected as the 2+ -The optimal pH for the H2O2-HYT reaction. Figure 7 As shown in B, when the reaction time is 5 minutes, △F 480 Reaching the peak value, △F increases with time 480 It remains unchanged, indicating that the 5-min experimental reaction has reached saturation. Therefore, 5 min is selected as the Co 2+ -The optimal time for H2O2-HYT reaction. Figure 7 As shown in C, as the temperature increases, △F at 25℃ 480 The temperature reaches the maximum value and then gradually decreases. Therefore, in this invention, 25℃ is selected as the temperature of Co 2+ -The optimal temperature of H2O2-HYT reaction. Figure 7 As shown in D, as the concentration of H2O2 increases, △F 480The system then reaches a maximum value and then reaches saturation. Therefore, 6mM is determined to be the optimal concentration of H2O2. 2+ The optimal experimental conditions for the -H2O2-HYT reaction system were pH 5.0, reaction temperature 25°C, reaction time 5 min, and H2O2 concentration 6 mM.

[0037] Example 5 Detection Performance Test of Cobalt Ions Under the optimal reaction conditions obtained from the above experimental data, the H2O2 / HYT / NR sensing system Co 2+ The detection performance of Figure 8 As shown in A, a series of different concentrations of Co 2+ Fluorescence spectroscopy was performed and the 2+ With the increase of the concentration, the fluorescence peak of the experimental system at 480 nm gradually weakened, and the fluorescence under 365 nm ultraviolet light also gradually weakened. Figure 8 As shown in B and C, when Co 2+ When the concentration is in the range of 0~5nM and 30~500nM, the fluorescence value of the reaction system at 480nm is the same as that of Co 2+ The concentration showed a good linear relationship, and the linear regression equations were y=-92.803[Co 2+ ]+1198.7(0-5nM, R 2 =0.9817) and y=-1.0769[Co 2+ ] + 507.65(30-500nM, R 2 =0.9637), and the method Co is obtained by 3σ / S calculation. 2+ The detection limit was 0.323 nM. Figure 8 As shown in E and F, when Co 2+ The concentration ranges from 0 to 5 nM and from 30 to 300 nM, and the absorbance of the reaction system at 460 nm is similar to that of Co 2+ The concentration showed a good linear relationship, and the linear regression equations were y =-0.0406[Co 2 + ]+0.3705(0-5nM, R 2 =0.9689) and y=-0.0025[Co 2+ ] +0.0939(30-300nM, R 2 =0.9886), and the Co of this method is calculated by 3σ / S 2+ The detection limit is 0.653nM. The fluorescence colorimetric sensor method established by the present invention is compared with some of the reported methods for detecting Co with fluorescent carbon dots and fluorescent probes. 2+Compared with the sensor of the present invention, the fluorescence colorimetric sensor constructed in the present invention has a lower detection limit.

[0038] Example 6 Cobalt Ion Selectivity Research Test In order to verify the method of the present invention for Co 2+ In order to determine the selectivity of the detection, the present invention investigated the fluorescence and colorimetric responses of different metal ions and anions in the HYT-NR-H2O2 system. Figure 9 As shown in A and B, Co 2+ The fluorescence signal generated by the experiment is significantly lower than that of other common metal ions and anions. 2+ Has higher selectivity.

[0039] In addition, the present invention also studies the sensing system for Co 2+ From Figure 10, it can be seen that almost all coexisting metal ions do not affect the anti-interference performance of Co 2+ These results show that the HYT-NR-H2O2 sensing system established in the present invention is sensitive to Co 2+ It has higher anti-interference ability.

[0040] Example 7 Detection test of cobalt ions in actual samples In order to test the application effect of this method in actual samples, the standard addition method was used to evaluate it. Lake water samples were collected on the campus of Nanchang Hangkong University and tap water samples were collected in the laboratory. Since there were no large solid particles in the water, the collected samples were only filtered with a 0.22 μm filter membrane and then used directly. 2+ It was added to the pretreated water sample for analysis, and the results are shown in Table 1.

[0041] The recovery rate of the actual water samples was 97.00%~103.56%, and the RSD was 2.7%~5.7%. In order to further investigate the accuracy of the method, we used ICP-MS to analyze the Co 2+ The results showed that the sensor we established was similar to the results obtained by ICP-MS, indicating that this method has high accuracy and can be used to detect Co in actual samples. 2+ Detection.

[0042] Table 1: ; The above embodiments are only preferred embodiments of the present invention and are not exhaustive of the feasible implementations of the present invention. For those skilled in the art, any obvious modifications made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A method for Co 2+ The composition for detecting fluorescence / colorimetric dual-mode sensing analysis is characterized in that The invention comprises the following components: hydroxytyrosol (HYT), H2O2, pH buffer and water; wherein the pH of the composition is 4.5-6.0, preferably 5.

0.

2. The composition according to claim 1, characterized in that The molar ratio of hydroxytyrosol (HYT) to H2O2 is 1:300-1000, preferably 1:

500.

3. The composition according to claim 1 or 2, characterized in that The pH buffer is HAc-NaAc buffer.

4. A method for detecting Co 2+ The fluorescence / colorimetric dual-mode sensing analysis method is characterized in that: The following steps are involved: Step (1) Prepare a solution with pH 4.5 to 6.0 by taking a certain amount of H2O2, hydroxytyrosol (HYT) and pH buffer, and add different concentrations of Co 2+ React for a while; Step (2) Add a certain amount of naphthalene diol (NR) and Na2CO3 buffer solution to the system obtained in step (1), adjust the pH of the system to 8.5-11, continue the reaction for a period of time, and then use a camera to photograph the fluorescence colorimetric effect of the solution under ultraviolet light (365 nm), and record the fluorescence spectrum at Ex=415 nm. Use a camera to photograph the colorimetric effect of the solution in a natural light environment, and scan and record its ultraviolet absorption spectrum.

5. The method according to claim 4, characterized in that The pH buffer in step (1) is HAc-NaAc buffer.

6. The method according to claim 4, characterized in that In step (1), the pH is 5.0, the reaction time is 5 min, the reaction temperature is 25° C., the H 2 O 2 concentration is 6 mM, and the hydroxytyrosol (HYT) concentration is 12 μM.

7. The method according to claim 4, characterized in that The different concentrations of Co in step (1) 2+ The concentration ranges were 0-5 nM and 30-500 nM.

8. The method according to claim 4, characterized in that In step (2), the pH is 11, the concentration of NR is 12 μM, the reaction time is 5 min, and the reaction temperature is 35°C.

9. The method according to any one of claims 4 to 8, characterized in that: When Co 2+ When the concentration ranges from 0 to 5 nM and from 30 to 500 nM, the fluorescence value of the reaction system at 480 nm is similar to that of Co 2+ The concentration showed a good linear relationship, and the linear regression equations were y = -92.803 [Co 2+ ]+1198.7(0-5nM, R 2 = 0.9817) and y =-1.0769[Co 2+ ] + 507.65(30-500nM, R 2 =0.9637), and the method Co is obtained by 3σ / S calculation. 2+ The detection limit was 0.323 nM; When Co 2+ The absorbance of the reaction system at 460nm was similar to that of Co in the concentration range of 0 ~ 5nM and 30 ~ 300nM. 2+ The concentration showed a good linear relationship, and the linear regression equations were y =-0.0406[Co 2+ ]+0.3705(0-5nM, R 2 =0.9689) and y=-0.0025[Co 2+ ] +0.0939(30-300nM, R 2 =0.9886), and the Co of this method is calculated by 3σ / S 2+ The detection limit was 0.653 nM.

10. The composition according to any one of claims 1 to 3 or the method according to any one of claims 4 to 9 is applied to Co in tap water or natural water. 2+ Purpose of the test.

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