Fluoride ion fluorescence detection method and device thereof

Abstract

The application discloses a kind of fluorine ion fluorescence detection method and device, belong to ion detection technical field, fluorescence detection method includes, to sample is pretreated, after being pretreated, sample is passed through solid-phase extraction column being equipped with cation exchange resin, obtain sample to be measured;Fluorine ion test reagent prepared is added to sample to be measured, obtain solution to be detected;The solution to be detected is transferred into quartz sample cell, and fluorine ion determination is carried out to the solution to be detected.The application improves the sensitivity and visualization ability of method by the unique Lewis acid-base interaction between scandium ion and fluorine ion, realizes the sensitive recognition and measurement of fluorine ion in sample.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ion detection, and particularly relates to a method for detecting fluorine ions by fluorescence and a device thereof. BACKGROUND

[0002] Fluoride is widely sourced and exists in various forms. In nature, inorganic fluorine usually exists in minerals such as fluorite, cryolite and mica stone, and enters groundwater, soil and atmosphere through geochemical processes. Human activities are an important reason for the source of fluorine in water bodies: usually, fluoride ions are added to toothpaste and drinking water to prevent dental caries, promote tooth remineralization and improve dental health, and enter water bodies with domestic water; waste water released by the production and processing of chemical raw materials, the medical industry, the microelectronics industry and other industries often also contains high concentrations of fluoride ions.

[0003] Although the use of fluorine brings many conveniences to human life, the large-scale production and application of fluorine-containing substances lead to the slow accumulation of fluorine in water bodies, causing serious damage to the environment and organisms. High concentrations of fluorine intake by the human body can cause fluorine poisoning, not only causing damage to teeth and bones (such as causing chronic symptoms such as dental fluorosis and skeletal fluorosis), but also inducing the calcification of the pineal gland in the brain, thereby causing damage to the nervous system. Therefore, many countries and organizations have strictly limited the content of fluorine in drinking water, for example, the allowable content of fluoride in drinking water in China is ≤ 1.0 mg / L, and the World Health Organization (WHO) has stipulated a limit of 1.5 mg / L. Although the content of fluoride in water is clearly defined, the discharge of industrial and domestic wastewater containing fluorine, the natural precipitation of minerals has made China one of the regions with high fluoride content in groundwater. Therefore, in order to protect public health and safety, it is very important to establish a real-time, rapid and sensitive portable on-site detection device for the analysis method of the content of fluorine ions in water bodies.

[0004] There are many laboratory methods for detecting fluoride ions, such as fluorine reagent spectrophotometry, ion chromatography and ion selective electrode method, etc. Although these methods have good detection sensitivity, there are still certain limitations, such as the need for bulky and expensive instrument equipment, time-consuming sample pretreatment, professional operators and complex experimental operations, etc., which are difficult to meet the needs of real-time detection on site. In order to solve the limitations of large instruments, in recent years, researchers have designed many small organic molecules as specific colorimetric probes for fluoride ions. Fluoride ions change the structure of small organic molecules through hydrogen bond interaction, deprotonation and displacement, and then produce color and / or fluorescence changes. These methods have excellent detection ability, but still have many shortcomings, for example, (1) poor specificity, easily interfered by anions with strong nucleophilic ability (such as CN-, AcO-, H2PO4-, etc.); (2) the design of specific organic molecular probes requires multi-step synthesis operation and the use of a large amount of organic reagents, which will cause certain reagent waste and damage to the environment; (3) the poor water solubility and water instability of organic molecules are still important factors limiting their application in actual water environment. Therefore, it is urgent to develop a probe with simple synthesis, high sensitivity to fluoride ions and rapid and simple operation for detecting fluoride ions in water environment. SUMMARY

[0005] One of the purposes of the present application is to provide a method for detecting fluoride ions by fluorescence, so as to solve the shortcomings of the prior art that the traditional detection method for fluoride ions is complex in operation, time-consuming, requires large instrument equipment, and is not suitable for real-time detection on site.

[0006] The application is achieved by the following technical scheme. A fluorine ion fluorescence detection method comprises the following steps: S100, pretreating a sample, and passing the pretreated sample through a solid-phase extraction column loaded with a cation exchange resin to obtain a to-be-detected sample; S200, adding a prepared fluorine ion testing agent to the to-be-detected sample to obtain a to-be-detected solution; S300, transferring the to-be-detected solution into a quartz sample cell, and determining the fluorine ion in the to-be-detected solution, wherein the step S300 comprises the following sub-steps: S310, transferring the to-be-detected solution into the quartz sample cell with a diameter of 10 mm and a height of 8 mm, and the total volume of the to-be-detected solution in the quartz sample cell is 400 muL; S320, then placing the quartz sample cell loaded with the to-be-detected solution into a darkroom, and using a light source with a wavelength of 410nm-420nm to irradiate the to-be-detected solution in the quartz sample cell from the side; S330, placing a long-wave pass filter with a center wavelength of 495 nm above the quartz sample cell of the to-be-detected solution, and taking a photo through the filter; S340, importing the taken photo into a color picking software, reading the RGB value of the solution part in the photo, recording the R and G channel values, importing the values into Origin software for graphing analysis, and obtaining a linear regression equation y=0.0511x+0.432 for detection, wherein y is the ratio of the R channel and the G channel, and x is the fluorine ion concentration.

[0007] Further, the pretreatment comprises adding calcium hydroxide solid powder into the to-be-detected sample, so that the concentration of calcium hydroxide in the to-be-detected sample reaches 5-10 mmol / L, then oscillating the to-be-detected sample for 1-3 min, standing for 5-10 min, and finally filtering through a 0.22 mu m filter head to obtain the to-be-detected sample.

[0008] Further, the fluorine ion testing agent comprises a buffer solution, a metal organic framework solution and a fluorescein sodium solution.

[0009] Further, the fluorine ion testing agent is prepared by the following steps: adding 8 muL of the metal organic framework solution, 12 muL of the fluorescein sodium solution and 40 muL of the buffer solution into a 0.5 mL centrifuge tube to prepare the fluorine ion testing agent.

[0010] Further, the buffer solution is a sodium acetate-acetic acid buffer solution, which is prepared by the following steps: weighing 0.3281 g of sodium acetate solid and adding it into 50 mL of ultrapure water, and gradually adding 50 times of ice acetic acid diluent, and stirring uniformly to prepare a sodium acetate-acetic acid buffer solution with a concentration of 100 mmol / L and a pH of 5.5; and the metal organic framework solution is a scandium metal organic framework solution.

[0011] Further, the solution to be detected is prepared by the following steps: 340 μL of the sample to be detected is taken and added to a 0.5 mL centrifuge tube containing 60 μL of the fluorine ion test agent, mixed uniformly, and then left to react for 3-5 min.

[0012] Further, the scandium metal organic framework solution is prepared by the following steps: 87.5 mg of tetra(4-carboxyphenyl)porphyrin is weighed and completely dissolved in 17 mL of DMF solution to prepare solution A; 28.7 mg of scandium chloride hexahydrate is weighed and completely dissolved in 3 mL of ultrapure water to prepare solution B; the prepared solutions A and B are mixed in a 50 mL glass reactor for microplasma treatment; the mixed solution after microplasma treatment is washed with dimethylformamide and ethanol for 3 times and then precipitated; the precipitate is dried in a vacuum freeze dryer for 12-24 h, and the precipitate after freeze drying is configured into a 0.5 mg / mL scandium metal organic framework solution with ultrapure water and stored in an environment of 0-4 ℃.

[0013] Further, the microplasma treatment comprises: the platinum electrode is completely immersed in the mixed solution in the glass reactor as an anode;

[0014] The hollow stainless steel tube is placed 3-5 mm above the liquid surface of the mixed solution in the glass reactor, and argon gas is blown into the liquid surface at a rate of 100 mL / min from the bottom of the hollow stainless steel tube; using a plasma discharge module, an input voltage of 7 V is applied to form a microplasma between the mixed solution and the bottom of the stainless steel tube; after discharging for 45-50 min, the mixed solution is placed in a centrifuge for centrifugal treatment, which comprises: the centrifuge speed is 10000-12000 rpm, and the centrifugal time is 20-30 min.

[0015] Further, the fluorescein sodium solution is a 10 μmol / L fluorescein sodium solution; the 10 μmol / L fluorescein sodium solution is prepared by the following steps: 3.76 mg of fluorescein sodium is weighed and placed in a 2 mL brown light-proof centrifuge tube; 1 mL of dimethyl sulfoxide is added to the centrifuge tube for dissolution to obtain a 10 mmol / L fluorescein sodium solution; the 10 mmol / L fluorescein sodium solution is diluted twice to obtain a 10 μmol / L fluorescein sodium solution.

[0016] Further, the two dilution operations comprise: 10 μL of the 10 mmol / L fluorescein sodium solution is taken from the centrifuge tube and diluted with ultrapure water to 1000 μL to obtain a first dilution solution; 100 μL of the first dilution solution is taken and diluted with ultrapure water to 1000 μL to finally obtain a 10 μmol / L fluorescein sodium solution.

[0017] Further, the linear correlation coefficient of the linear equation is 0.999, and the linear range is 1-80 μmol / L.

[0018] Another aspect of the present application provides a fluoride ion fluorescence detection device, which can realize the fluoride ion fluorescence detection method according to any one of the above, and the detection device comprises a light source, a push-pull base, a battery compartment, a light source, a filter and a shell; a hole for taking pictures is opened on the upper part of the shell, and a filter is placed below the hole, the filter is a long-wave pass filter of 495 nm, and a to-be-detected quartz sample cell is below the filter, the diameter of the to-be-detected quartz sample cell is 10 mm, the height is 8 mm, and the solution volume contained is 400 μL; the push-pull base is used for placing the to-be-detected quartz sample cell, and the position of the to-be-detected quartz sample cell is adjusted by the push-pull base so that it is located directly below the photographing hole; the battery compartment is connected with the light source for power supply of the light source, the light source is placed in the push-pull base, and after being turned on, the to-be-detected quartz sample cell can be irradiated from below, the light source is an LED lamp bead with a wavelength of 410 nm-420 nm, a voltage of 3 V and a power of 3 W; the shell is an outer box with a length of 120 mm, a width of 71.5 mm and a height of 100 mm, which is printed by a 3D printer, and the material is black opaque resin.

[0019] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0020] 1. The present application uses liquid anode glow discharge microplasma technology to assist in synthesizing scandium metal organic framework, which has the advantages of simple operation, fast synthesis speed and low energy consumption.

[0021] 2. The present application uses the unique Lewis acid-base interaction between Sc 3+ (scandium ions) and (fluoride ions), and

[0022] By introducing fluorescein sodium and combining with the fluorescence inner filter effect, a ratio fluorescence system is constructed to detect the significant signal change caused by the combination of Sc 3+ (scandium ions) and (fluoride ions), which improves the sensitivity and visualization ability of the method and realizes the sensitive identification and measurement of fluoride ions in the sample.

[0023] 3. The present application meets the demand of real-time detection on site by combining with a smart phone, and makes the whole operation process more convenient and the detection cost lower. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0025] Figure 1 Method flow chart for exemplary embodiment 1 of the present application.

[0026] Figure 2 Synthesis principle diagram of scandium metal organic framework solution for exemplary embodiment 1 of the present application.

[0027] Figure 3 Ratio-type fluorescent ion sensing diagram for exemplary embodiment 1 of the present application.

[0028] Figure 4 Fluoride ion detection device schematic diagram for exemplary embodiment 2 of the present application.

[0029] Figure 5 Water sample analysis flow chart based on the fluoride ion detection device for exemplary embodiment 2 of the present application.

[0030] Figure 6 Standard curve diagram for detecting fluoride ions for exemplary embodiment 1 of the present application. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All publications mentioned in this specification are herein incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference in this specification is not an admission that it is prior art to the present application. To the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall control. As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” and the like are open-ended terms that mean “including but not limited to.” Unless otherwise noted, the terms “a” and “an” are taken to mean one or more. For example, the term “a cell” includes multiple such cells and equivalents thereof known to those skilled in the art. As used herein, the term “about” means ±20% of the numerical value of the number that it precedes. In some embodiments, the term “about” means ±10% of the numerical value of the number that it precedes. In some embodiments, the term “about” means ±5% of the numerical value of the number that it precedes.

[0033] Example 1,

[0034] Figure 1 A method flow chart of the present example embodiment is shown, which provides a method for detecting fluorine ions by fluorescence. Specifically, the method comprises the following steps:

[0035] Step 1: Pretreat the sample, and pass the pretreated sample through a solid-phase extraction column loaded with cation exchange resin to obtain a sample to be tested.

[0036] Specifically, by adding calcium hydroxide solid powder to the sample, the concentration of calcium hydroxide in the sample to be tested reaches 5-10 mmol / L, then oscillate the sample to be tested for 1-3 min, stand for 5-10 min, and finally filter through a 0.22 μm filter head to obtain the sample to be tested.

[0037] Step 2: Add the prepared fluorine ion test agent to the sample to be tested to obtain a solution to be tested.

[0038] Specifically, the fluorine ion test agent can include a buffer solution, a metal organic framework solution, and a fluorescein sodium solution

[0039] The fluorine ion test agent is prepared by the following method: 8 μL of metal organic framework solution, 12 μL of fluorescein sodium solution and 40 μL of buffer solution are added to a 0.5 mL centrifuge tube to prepare the fluorine ion test agent.

[0040] The buffer solution is a sodium acetate-acetic acid buffer solution, which is prepared by the following steps: 0.3281 g of sodium acetate solid is weighed and added to 50 mL of ultrapure water, and 50 times of ice acetic acid diluent is gradually added, stirred uniformly, to prepare a sodium acetate-acetic acid buffer solution with a concentration of 100 mmol / L and pH=5.5;

[0041] The metal organic framework solution is a scandium metal organic framework solution.

[0042] Specifically, the scandium metal organic framework solution is prepared by the following steps:

[0043] 87.5 mg of tetra(4-carboxyphenyl)porphyrin is weighed and completely dissolved in 17 mL of DMF solution to prepare solution A.

[0044] 28.7 mg of scandium chloride hexahydrate is weighed and completely dissolved in 3 mL of ultrapure water to prepare solution B.

[0045] The prepared solutions A and B are mixed in a 50 mL glass reactor for microplasma treatment.

[0046] Specifically, the micro-plasma treatment includes completely immersing the platinum electrode as an anode into the mixed solution in the glass reactor.

[0047] A hollow stainless steel tube is placed 3-5 mm above the liquid surface of the mixed solution in the glass reactor, and argon gas is blown into the liquid surface at a rate of 100 mL / min from the bottom of the hollow stainless steel tube. For example, the hollow stainless steel tube can be located 3, 3.4, 4, 4.6 mm above the liquid surface.

[0048] Using the plasma discharge module, a micro-plasma is formed between the mixed solution and the bottom of the stainless steel tube after applying a 7V input voltage.

[0049] After discharging for 45-50 min, the mixed solution is placed in a centrifuge for centrifugal treatment, which includes a centrifuge speed of 10000-12000 rpm and a centrifugal time of 20-30 min. For example, the discharging time can be 46, 47, 49 min; the centrifuge speed can be 10000, 11200, 11500, 11900 rpm.

[0050] The mixed solution after micro-plasma treatment is washed with dimethylformamide and ethanol for 3 times and then precipitated. The purpose of washing in this step is to remove residual TCPP tetra(4-carboxyphenyl)porphyrin and Sc 3+ (scandium ions).

[0051] The precipitate is dried in a vacuum freeze dryer for 12-24 h, and the precipitate obtained after freeze-drying is configured into a 0.5 mg / mL scandium metal organic framework solution with ultrapure water and stored in an environment of 0-4 ℃. For example, the drying time can be 13, 15, 22, 23 h; the storage temperature can be 0, 1.5, 2, 3.5 ℃.

[0052] Figure 2 The synthesis principle diagram of the scandium metal organic framework solution in this step is shown. As can be seen from the figure, the principle of synthesizing scandium (Sc) metal organic framework (Sc-TCPP MOF) by liquid anode glow discharge (SAGD) method. A large number of high-energy electrons generated during the SAGD process in an argon atmosphere will deprotonate the organic ligand TCPP, thereby promoting the combination of the metal and the ligand, and further accelerating the formation of MOF.

[0053] Specifically, the fluorescein sodium solution can be a fluorescein sodium solution with a concentration of 10 μmol / L.

[0054] The fluorescein sodium solution with a concentration of 10 μmol / L can be prepared by the following steps:

[0055] Weigh 3.76 mg of sodium fluorescein and place it in a 2 mL brown non-transparent centrifuge tube.

[0056] Add 1 mL of dimethyl sulfoxide to the centrifuge tube for dissolution, to obtain a 10 mmol / L sodium fluorescein solution.

[0057] Take 10 μL of the 10 mmol / L sodium fluorescein solution from the centrifuge tube and dilute it to 1000 μL with ultrapure water to obtain a first dilution solution.

[0058] Take 100 μL of the first dilution solution and dilute it to 1000 μL with ultrapure water to obtain a 10 μmol / L sodium fluorescein solution. After two dilution operations, a 10 μmol / L sodium fluorescein solution is obtained.

[0059] Specifically, the test solution is prepared by the following steps:

[0060] Add 340 μL of the sample to be tested to a 0.5 mL centrifuge tube containing 60 μL of a fluoride ion test agent, mix well, and let it stand for 3-5 min.

[0061] Step 3: Transfer the test solution into a quartz sample cell and measure the fluoride ion in the test solution.

[0062] Specifically, the following sub-steps are included:

[0063] 1) Transfer the test solution into a quartz sample cell with a diameter of 10 mm and a height of 8 mm, and the total volume of the test solution in the quartz sample cell is 400 μL.

[0064] 2) Then place the quartz sample cell containing the test solution in a dark room, and use a light source with a wavelength of 410 nm-420 nm to irradiate the test solution in the quartz sample cell from below.

[0065] 3) Place a long-wave pass filter with a center wavelength of 495 nm above the quartz sample cell containing the test solution, and take a photo through the filter. Specifically, when taking a photo with a camera, various parameters of the camera have a certain influence on the final imaging. When performing fluorescence detection, the sensitivity and shutter speed of the camera have the greatest impact on the final fluorescence imaging effect. In order to make the detection results consistent, the sensitivity (ISO) of the camera should be set to 250 and the shutter speed (s) should be set to 1 / 15 s.

[0066] 4) The taken photos were imported into the color extraction software to read the RGB values of the solution part of the photos, record the R and G channel values, and import them into the Origin software for plotting and analysis to obtain the linear regression equation. The linear regression equation obtained was y = 0.0511x + 0.432, and the linear correlation coefficient was 0.999. In the linear regression equation, as the concentration of fluoride ions increased, the R / G value gradually increased, and the two were linearly correlated, and the corresponding fluoride ion concentration could be calculated by the R / G value.

[0067] Figure 3 The ratio-type fluorescence-to-fluoride ion sensing in the present exemplary embodiment is shown. As can be seen from the figure, after the Sc-TCPP MOF is formed, the red fluorescence of TCPP itself is quenched by the photo-induced electron transfer effect (PET). Subsequently, after the action of the measured fluoride ion, the Sc with strong Lewis acid properties in the MOF combines with the fluoride ion with Lewis base properties, affecting the structure itself and the energy transfer from the ligand to the metal, thereby enabling the red fluorescence of the MOF. In addition, in order to improve the visualization ability of the signal, a fluorescein with green emission is introduced into the system to construct a ratio fluorescence sensing system through the inner filter effect.

[0068] In summary, it can be seen that when the concentration of fluoride ions is low, the Sc located at the center of the porphyrin ring of TCPP will usually act first, the red fluorescence of the MOF (scandium metal organic framework) is turned on, and the green fluorescence of the fluorescein in the system is reduced through the inner filter effect; as the concentration of fluoride ions increases, the structure of the MOF (scandium metal organic framework) collapses, TCPP is released and exhibits its own strong red fluorescence. Through the CMOS sensor of the camera, the visualization reading of the fluorescence signal from green to red can be realized, the detection linear range is 1~80 μM, the detection limit is 0.24 μM, and the demand for on-site and timely detection (POCT) is met.

[0069] Exemplary Embodiment 2,

[0070] A fluoride ion fluorescence detection device is provided in the present exemplary embodiment, and through the device and in combination with the fluoride ion fluorescence detection method described in exemplary embodiment 1, the detection of fluoride ion fluorescence can be better realized.

[0071] The fluoride ion fluorescence detection device specifically includes a light source, a push-pull base, a battery compartment, a light source, a filter, and a housing.

[0072] A hole for taking pictures is opened in the upper part of the housing, and a filter is placed below the hole. The filter is a long-wave pass filter with a wavelength of 495 nm, and a to-be-detected quartz sample cell is below the filter. The diameter of the to-be-detected quartz sample cell is 10 mm, the height is 8 mm, and the volume of the contained solution is 400 μL.

[0073] The push-pull base is used to place the quartz sample cell to be detected. The position of the quartz sample cell to be detected is adjusted by the push-pull base, so that it is located directly below the shooting opening.

[0074] The battery compartment is connected with the light source for powering the light source. The light source is placed in the push-pull base and can irradiate the quartz sample cell to be detected from below after being turned on. The light source is a 410 nm-420 nm LED lamp bead, the voltage is 3 V, and the power is 3 W.

[0075] The shell is an outer box with a length of 120 mm, a width of 71.5 mm, and a height of 100 mm, which is printed by a 3D printer. The material is black opaque resin.

[0076] Figure 4 A schematic diagram of the fluorine ion detection device of the present exemplary embodiment is shown, Figure 5 A water sample analysis flowchart of the fluorine ion detection device of the present exemplary embodiment is shown.

[0077] In order to better understand the fluorine ion fluorescence detection method provided in the present exemplary embodiment, the content of the method is further illustrated below in combination with the drawings and examples.

[0078] Example 1

[0079] In the present embodiment, N,N-dimethylformamide (DMF), glacial acetic acid, sodium acetate, ethanol and calcium hydroxide solid were purchased from Chengdu Kolon Chemical Co., Ltd.; scandium chloride hexahydrate and fluorescein sodium were purchased from Aladdin Biochemical Technology Co., Ltd.; meso-tetra(4-carboxyphenyl) porphyrin (TCPP) was purchased from Macklin Biochemical Technology Co., Ltd.; Amberlite (R) IRC120H type cation exchange resin was purchased from Titan Technology Co., Ltd.

[0080] First, configure the fluorine ion test agent.

[0081] Preparation of buffer solution: weigh 0.3281 g of sodium acetate solid in 50 mL of ultrapure water, gradually add 50 times of glacial acetic acid diluent, stir uniformly, and read the pH value of the solution with a pH meter. Repeat the operation until the pH of the solution is stable at 5.5. Finally, a sodium acetate-acetic acid buffer solution with a concentration of 100 mmol / L and a pH of 5.5 is obtained.

[0082] Preparation of sodium fluorescein solution: 3.76 mg of sodium fluorescein was weighed into a 2 mL brown non-transparent centrifuge tube, 1 mL of dimethyl sulfoxide was added to dissolve it, obtaining a sodium fluorescein solution with a concentration of 10 mmol / L. 10 μL of the 10 mmol / L sodium fluorescein solution was diluted to 1000 μL with ultrapure water, and then 100 μL of the diluted solution was diluted to 1000 μL with ultrapure water, obtaining a 10 μmol / L sodium fluorescein solution for standby use.

[0083] Synthesis of Sc-MOF solution:

[0084] 87.5 mg of TCPP was weighed and completely dissolved in 17 mL of DMF solution to obtain solution A. 28.7 mg of scandium chloride hexahydrate was accurately weighed and completely dissolved in 3 mL of ultrapure water to obtain solution B. Solution A and solution B were mixed in a 50 mL glass reactor for microplasma treatment. A hollow stainless steel tube was located about 3 mm above the liquid surface, and argon was blown into the liquid surface at a rate of 100 mL / min from the bottom of the stainless steel tube. A platinum electrode was used as an anode and was completely immersed in the solution. A DP-GB 15 kV-ignition type (China, Guangao Electronics) was used as a plasma discharge module, and after an input voltage of 7 V was applied, a microplasma was formed between the solution and the bottom of the stainless steel tube. After continuous discharge for 45 min, the precipitate was obtained by centrifugation at 10000 rpm for 20 min. The precipitate was washed 3 times with DMF and ethanol to remove residual TCPP and Sc 3+ . Finally, the precipitate was dried in a vacuum freeze dryer for 12 h. The obtained precipitate was configured into a 0.5 mg / mL stock solution and stored in a 0-4 ℃ refrigerator for standby use.

[0085] In a 0.5 mL centrifuge tube, 8 μL of metal organic framework solution, 12 μL of sodium fluorescein solution and 40 μL of buffer solution were added to prepare a fluoride ion test agent.

[0086] Then the sample to be tested was prepared, 4 mL of water sample was taken, 3 mg of Ca(OH)2 solid powder (final concentration of 10 mmol / L) was added, and shaken for 2 min. After standing for 8 min, it was filtered with a 0.22 μm filter head, and the filtrate was collected. Subsequently, the filtrate was passed through a solid phase extraction column filled with cation exchange resin and collected in a centrifuge tube. 340 μL of the solution was taken, and 40 μL of the fluoride ion test agent was added. After mixing evenly, it was allowed to stand for 4 min of reaction. Subsequently, the reaction solution was transferred into a quartz sample cell, and a photograph was taken and colorimetric analysis was performed.

[0087] Specifically, when taking pictures with the camera, various parameters of the camera have certain influence on the final imaging. When performing fluorescence detection, the sensitivity and shutter speed of the camera have the greatest influence on the final fluorescence imaging effect. In order to make the detection effect consistent, the sensitivity (ISO) of the camera should be set to 250, and the shutter speed (s) should be set to 1 / 15 s.

[0088] The photographed picture is imported into the color picking software ImageJ, the color of the solution part is circled by using the circular selection tool, the R and G channel values in the picture are calculated by using the color picking function of the software itself, and the R / G value is calculated. The linear regression equation y = 0.0511x + 0.432 is obtained, and the linear correlation coefficient is 0.999. In the linear regression equation, as the concentration of fluoride ions increases, the R / G value gradually increases, and they are linearly correlated. The corresponding concentration of fluoride ions can be calculated by the R / G value.

[0089] Figure 6 The standard curve for detecting fluoride ions in the embodiment is shown. In the figure, the X axis represents the concentration of fluoride ions, and the Y axis represents the ratio of the R channel and the G channel. The upper 0~80 represents the linear range of 1~80 μmol / L.

[0090] According to the principle described above, as the concentration of fluoride ions increases, the red fluorescence of MOF in the fluoride ion detection solution will also correspondingly increase. Therefore, the redder the color of the solution in the picture, the higher the concentration of fluoride ions in the to-be-measured solution, and the greener the color of the solution, the lower the concentration of fluoride ions in the to-be-measured solution.

[0091] The existing traditional detection method for fluoride ions is generally limited by complex operation, long time consumption, and the need for large-scale instrument equipment, and is not suitable for real-time detection on site. In recent years, optical detection technology has been widely concerned due to its low cost, simplicity, rapidness, excellent signal reading capacity and other advantages. Designing optical probes with excellent response to F- has become the focus of scientists' research. Many organic small molecules (such as anthracene, benzimidazole, BODIPY, calixarene, Schiff base, etc. modified with various functional groups) have been designed and synthesized to realize the detection of F-. These methods have good sensitivity, but still have many limitations, such as complex synthesis method, detection in non-aqueous or semi-aqueous medium, poor ion selectivity, etc. In the embodiment, a microplasma assisted synthesis method, liquid anode glow discharge (SAGD) technology, is used to synthesize Sc-TCPP MOF simply, quickly and with low energy consumption. Under a reducing gas atmosphere, SAGD technology can generate a large number of high-energy electrons and reducing radicals, causing rapid deprotonation of the organic linker (TCPP), thereby accelerating the combination of Sc 3+ with TCPP and further forming a metal-organic framework crystal structure.

[0092] After the MOF is formed, the red fluorescence (optimum emission 646 nm) of TCPP itself disappears, and after the action with F-, the red fluorescence of the MOF is turned on. In addition, the addition of fluorescein sodium with green fluorescence (optimum emission 514 nm) constructs a ratiometric fluorescent system, which improves the detection sensitivity.

[0093] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for fluorometric detection of fluoride ions, characterized in that, The fluorescence detection method comprises, S100, pretreating the sample, and passing the pretreated sample through a solid-phase extraction column loaded with a cation exchange resin to obtain a to-be-tested sample; S200, adding the prepared fluoride ion testing agent to the to-be-tested sample to obtain a to-be-tested solution; S300, transferring the to-be-tested solution into a quartz sample cell, and determining the fluoride ion in the to-be-tested solution; The step S300 comprises the following sub-steps: S310, transferring the to-be-tested solution into a quartz sample cell with a diameter of 10 mm and a height of 8 mm, and the total volume of the to-be-tested solution in the quartz sample cell is 400 μL; S320, then placing the quartz sample cell loaded with the to-be-tested solution into a dark room, and using a light source with a wavelength of 410 nm to 420 nm to irradiate the to-be-tested solution in the quartz sample cell from the side; S330, placing a long-wave pass filter with a center wavelength of 495 nm above the quartz sample cell of the to-be-tested solution, and taking a photo through the filter; S340, importing the taken photo into a color picking software, reading the RGB value of the solution part in the photo, recording the R and G channel values, importing the values into Origin software for graphing analysis, and obtaining a linear regression equation y = 0.0511x + 0.432 for detection, wherein y is the ratio of the R channel and the G channel, and x is the fluoride ion concentration; The fluoride ion testing agent comprises a buffer solution, a metal organic framework solution and a fluorescein sodium solution, The fluoride ion testing agent is prepared by the following steps: In a 0.5 mL centrifuge tube, 8 μL of the metal organic framework solution, 12 μL of the fluorescein sodium solution and 40 μL of the buffer solution are added to prepare the fluoride ion testing agent; The buffer solution is a sodium acetate-acetic acid buffer solution, which is prepared by the following steps: 0.3281 g of sodium acetate solid is weighed and added to 50 mL of ultrapure water, and 50 times of glacial acetic acid diluent is gradually added, and stirred uniformly to prepare a sodium acetate-acetic acid buffer solution with a concentration of 100 mmol / L and a pH of 5.5; The metal organic framework solution is a scandium metal organic framework solution.

2. The method for fluorine ion fluorescence detection according to claim 1, characterized in that, The pretreatment comprises adding calcium hydroxide solid powder to the sample, so that the concentration of calcium hydroxide in the to-be-tested sample reaches 5 to 10 mmol / L, then oscillating the to-be-tested sample for 1 to 3 min, standing for 5 to 10 min, and finally filtering through a 0.22 μm filter head to obtain the to-be-tested sample.

3. The method of claim 1, wherein the method is used to detect the presence of fluoride ions in a sample. The to-be-tested solution is prepared by the following steps: 340 μL of the to-be-tested sample is taken and added to a 0.5 mL centrifuge tube containing 60 μL of the fluoride ion testing agent, and after being mixed uniformly, it is left to stand for 3 to 5 min.

4. The method of claim 1, wherein the method is used to detect the presence of fluoride ions in a sample. The scandium metal organic framework solution is prepared by the following steps: 87.5 mg of tetra(4-carboxyphenyl)porphyrin is weighed and completely dissolved in 17 mL of DMF solution to prepare solution A; 28.7 mg of scandium chloride hexahydrate is weighed and completely dissolved in 3 mL of ultrapure water to prepare solution B; The prepared A solution and B solution are mixed in a 50 mL glass reactor for microplasma treatment; After the microplasma treatment, the mixed solution is washed with dimethylformamide and ethanol for 3 times and then precipitated; The precipitate is dried in a vacuum freeze dryer for 12-24 h, and the precipitate obtained after freeze drying is configured into a 0.5 mg / mL scandium metal organic framework solution with ultrapure water and stored in an environment of 0-4 ℃.

5. The fluoride ion fluorescence detection method according to claim 4, characterized in that, The microplasma treatment comprises: The platinum electrode is completely immersed in the mixed solution in the glass reactor as an anode; A hollow stainless steel tube is placed 3-5 mm above the liquid surface of the mixed solution in the glass reactor, and argon gas is blown into the liquid surface at a rate of 100 mL / min from the bottom of the hollow stainless steel tube; Using a plasma discharge module, a microplasma is formed between the mixed solution and the bottom of the stainless steel tube after applying a 7V input voltage; After discharging for 45-50 min, the mixed solution is placed in a centrifuge for centrifugal treatment, which comprises a centrifuge speed of 10000-12000 rpm and a centrifugal time of 20-30 min.

6. The method of claim 1, wherein the method is used to detect the presence of fluoride ions in a sample. The sodium fluorescein solution is a 10 μmol / L sodium fluorescein solution; The 10 μmol / L sodium fluorescein solution is prepared by the following steps: 3.76 mg of sodium fluorescein is weighed and placed in a 2 mL brown non-transparent centrifuge tube; 1 mL of dimethyl sulfoxide is added to the centrifuge tube for dissolution to obtain a 10 mmol / L sodium fluorescein solution; The 10 mmol / L sodium fluorescein solution is diluted twice to obtain a 10 μmol / L sodium fluorescein solution.

7. The method of claim 6, wherein the method is used to detect the presence of fluoride ions in a sample. The two dilution operations comprise taking 10 μL of the 10 mmol / L sodium fluorescein solution from the centrifuge tube and diluting it to 1000 μL with ultrapure water to obtain a first dilution solution; 100 μL of the first dilution solution is taken and diluted to 1000 μL with ultrapure water to finally obtain a 10 μmol / L sodium fluorescein solution.

8. The method of claim 1, wherein the method is used to detect fluoride ions. The linear correlation coefficient of the linear equation is 0.999, and the linear range is 1-80 μmol / L.

9. A fluorine ion fluorescence detecting device characterized by comprising: The detection device applies the method of any one of claims 1-8, and the detection device comprises a light source, a push-pull base, a battery compartment, a light source, a filter, and a housing; An opening for taking pictures is opened on the upper part of the housing, and a filter is placed below the opening, the filter is a long-wave pass filter of 495 nm, and a to-be-detected quartz sample cell is below the filter, the to-be-detected quartz sample cell has a diameter of 10 mm, a height of 8 mm, and a solution volume of 400 μL; The push-pull base is used to place the to-be-detected quartz sample cell, and the position of the to-be-detected quartz sample cell is adjusted by the push-pull base so that it is located directly below the photographing opening; The push-pull base is used to place the to-be-detected quartz sample cell, and the position of the to-be-detected quartz sample cell is adjusted by the push-pull base so that it is located directly below the photographing opening; The battery compartment is connected with the light source for powering the light source, the light source is placed in the push-pull base, and after being turned on, it can irradiate the quartz sample cell to be detected from below, the light source is an LED lamp bead with a wavelength of 410 nm to 420 nm, a voltage of 3 V and a power of 3 W; The shell is a long 120 mm, wide 71.5 mm, high 100 mm outer box printed by a 3D printer, and the material is black opaque resin.

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