Method for detecting fluorine ions in water body based on smart phone

Abstract

The invention discloses a method for detecting fluorine ions in a water body based on a smart phone, and belongs to the technical field of fluorine ion detection. According to the portable detection equipment based on the smart phone, laser emitted by the laser pen is divided into two beams through the beam splitter, then a to-be-detected liquid is compared with a sample with a fixed concentration, the smart phone is used for shooting a picture, and then the RGB value of an effective area is identified, so that the G ratio of the to-be-detected liquid to the sample with the fixed concentration is obtained; according to the method, a linear relation between fluorine ions with different concentrations and G ratios is constructed, high-sensitivity detection of F <-> is realized, compared with traditional fluorospectro photometer detection, the sensitivity is higher, the technical problem of test result deviation caused by instability of a rechargeable light source used in the field detection process in the prior art is solved, and the method is suitable for large-scale popularization and application. According to the invention, on-site detection of the water sample to be detected can be realized through the smart phone.

Description

Technical Field

[0001] The present invention relates to the technical field of fluoride ion detection in water, and in particular to a method for detecting fluoride ions in water based on a smart phone. Background Art

[0002] Fluorine is one of the essential trace elements for the human body. It not only promotes the formation of bone tissue but also has a beneficial effect on the health of teeth. However, excessive intake of fluoride can cause fluorosis diseases such as dental fluorosis and skeletal fluorosis, and even lead to brain damage and reproductive system dysfunction in severe cases. To prevent these diseases, the World Health Organization has set the concentration limit of fluoride ions in drinking water at 1.5 mg / L (78.9 μM). At present, in nature, the dissolution of fluoride-rich rocks such as fluorite, oxyfluorite, and cryolite may cause groundwater to contain high concentrations of fluoride ions and be polluted; and in human activities, such as the discharge of wastewater generated by metal processing, fertilizers, and glass manufacturing industries into surface water, it will also lead to an increase in the concentration of fluoride ions in surface water and groundwater. Therefore, the detection of fluoride ion concentration levels in water bodies has always attracted much attention.

[0003] At present, various instruments and technologies are used to detect fluoride ions in water, including ion chromatography, ion selective electrodes, surface enhanced Raman scattering, chemiluminescence, mass spectrometry, colorimetry and fluorescence. Among these methods, colorimetry and fluorescence methods have been widely studied and have developed relatively maturely, but most of their sensors can only be used in laboratories and are not suitable for on-site detection and places where there is a lack of experimental environment. For some water quality surveys and water pollution incidents, it is often necessary to quickly determine the specific concentration of fluoride ions in water on site. Therefore, developing a portable device for on-site detection of fluoride ions for the detection and monitoring of fluoride ions in water will become a new goal and development direction.

[0004] In the prior art, portable devices based on smartphones have been developed. For example, CN2022201458801 discloses a portable sample solution colorimetric analysis device based on the camera function of a smartphone, which ensures a stable background of the shooting environment and a constant shooting angle, thereby reducing errors caused by different shooting angles. However, the light source in this patent is an LED lamp, which is powered by an OTG adapter, a power bank, or a mobile phone charger.

[0005] CN201810510382.0 discloses a colorimetric sensor for fluoride ions in water based on a smartphone and its application. It includes a monochromatic LED light source, a diffuser plate, a sample cell, a lens and a mobile phone. The wavelength of the monochromatic LED light source in the invention is 560-580nm, but in order to achieve on-site testing, the light source is generally required to be rechargeable.

[0006] The inventors found that the stability of the light source, as one of the core elements of the smartphone-assisted portable detection device, directly determines the performance of the detection system. Since the rechargeable light source does not need to be connected to a power source for continuous power supply, it can be used on site at any time in practical applications without being restricted by the environment. However, the output power of the rechargeable light source often fluctuates with the battery usage time, resulting in poor light source stability, which directly affects the detection results. Figure 1 As shown, a commercially available rechargeable laser pen is used as the light source. The inventor found that when the laser pen is used at 30 m i During the n time, the laser power is not output stably but fluctuates. When the battery is exhausted after being used for more than 30 minutes, the laser power decreases rapidly, which will directly affect the test results. Summary of the invention

[0007] In order to solve the technical problems existing in the prior art, the present invention provides a method for detecting fluoride ions in water based on a smart phone. The present invention uses a liquid to be tested and a sample of a fixed concentration as a comparison, and uses a smart phone to shoot and identify RGB values, thereby obtaining the G ratio of the liquid to be tested and the sample of the fixed concentration, and constructing a linear relationship between fluoride ions of different concentrations and the G ratio, thereby solving the technical problem in the prior art that the instability of the rechargeable light source leads to deviation in the test results.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] On the one hand, the present invention provides a portable detection device based on a smart phone, including a beam splitter, a reflector, a cuvette, a cover, a hollow cylinder, a conical cylinder cover, a smart phone fixing slot, a mobile phone camera shooting hole, a laser pen fixing cylinder and a detection box;

[0010] The detection box is provided with a partition plate for dividing the detection box into a light mirror area and a sample area; the partition plate is provided with light-transmitting holes, and the light-transmitting holes include a first light-transmitting hole and a second light-transmitting hole;

[0011] The optical mirror area is used to place the beam splitter and the reflector, and the cover is used to make the optical mirror area a dark room; the sample area is used to place the cuvette, and the conical tube cover is used to make the sample area a dark room, and the cuvette includes a first cuvette and a second cuvette;

[0012] In the optical mirror area, an incident hole is provided on the side wall of the detection box, the laser pen fixing tube is used to fix the laser pen on the side wall of the detection box, the laser emitted by the laser pen is irradiated onto the beam splitter through the incident hole, and the beam splitter is used to split the laser into two laser beams with little difference in power and perpendicular to each other; one laser beam is irradiated onto the first cuvette through the first light-transmitting hole, and the other laser beam is irradiated onto the reflector, and is reflected by the reflector and then irradiated onto the second cuvette through the second light-transmitting hole;

[0013] The top of the conical cylinder cover is fixedly connected to the hollow cylinder, a filter is arranged in the middle of the hollow cylinder, the top of the hollow cylinder is fixed with the smartphone fixing groove, a mobile phone camera shooting hole is arranged at the connection position between the smartphone fixing groove and the hollow cylinder, and a smartphone can be used to take photos of the sample area through the mobile phone camera shooting hole.

[0014] Preferably, a support frame is provided below the laser pen fixing tube for supporting the laser pen fixing tube;

[0015] The bottom of the detection box is provided with two positioning posts, namely a first positioning post and a second positioning post. Said A thread is provided on the top of the positioning column; the beam splitter is fixed by a beam splitter optical adjustment frame, and the reflector is fixed by a reflector optical adjustment frame. Internal threads are provided at the bottom of the beam splitter optical adjustment frame and the reflector optical adjustment frame, and the beam splitter optical adjustment frame and the reflector optical adjustment frame are fixed on the first positioning column and the second positioning column respectively;

[0016] The bottom of the detection box is provided with two sample slots, namely a first sample slot and a second sample slot. The first sample slot is used to fix the first cuvette, and the second sample slot is used to fix the second cuvette.

[0017] On the other hand, the present invention also provides a method for detecting fluoride ions in water based on a smart phone, comprising:

[0018] Step 1: Prepare MOF material using AlCl3·6H2O and 2-aminoterephthalic acid as raw materials, and encapsulate the fluorescent reagent in MOF to obtain the new fluorescent material MR;

[0019] Step 2: MR is prepared into a solution, mixed with a fluoride ion solution in a set ratio to form a mixed solution, and incubated;

[0020] Step 3: Place the incubated mixture into the portable detection device and use the fluorescent reagent as a reference; turn on the laser pen and take a photo of the sample area using a smartphone;

[0021] Step 4: Cut out the effective excitation area from the photograph, and obtain the G value in the RGB values ​​of the corresponding areas of the sample solution and the reference solution respectively; then calculate the ratio of the G value of the sample solution to the G value of the reference solution, which is recorded as the G ratio;

[0022] Sequentially take photos of fluoride ion mixed solutions with different concentrations, intercept the effective areas of each to identify the G value in the corresponding RGB value, calculate the G ratio, and establish a standard working curve with the fluoride ion concentration as the horizontal axis and the G ratio as the vertical axis;

[0023] Step 5: After the water sample to be tested is pretreated, the corresponding G ratio is determined by analogy with the above steps S2-S4, and the fluoride ion concentration of the water sample to be tested is calculated in combination with the standard working curve.

[0024] Furthermore, the step 1 is specifically as follows:

[0025] (11) AlCl3·6H2O, 2-aminoterephthalic acid and DMF were added to a beaker and ultrasonically mixed, then added to a reactor and heated in an oven at 130° for 72 h. After heating, the yellow product was separated by centrifugation, and a yellow powder (MOF) was obtained by washing, drying and grinding.

[0026] (12) Rhodamine B (RhB) and MOF were placed in anhydrous ethanol and ultrasonically mixed. The mixture was placed in a constant temperature oscillating box and stirred for more than 12 h. After the oscillation was completed, the mixture was centrifuged and washed until the fluorescence intensity of the supernatant no longer changed. Finally, the product was dried to obtain a light red powder MOF@RhB (MR).

[0027] Furthermore, the step 2 is specifically as follows:

[0028] Disperse MR ultrasound uniformly in ultrapure water to obtain an MR concentration of 0.15-0.3 mg / mL; mix 3 mL of fluoride ion solution and 200 μL of MR solution, transfer to a water bath and incubate at 70°C for 10 min; after the incubation is completed and cooled to room temperature, the measurement can be performed;

[0029] Preferably, the fluoride ion solution is a solution containing fluoride ions, and the fluoride ion concentration is 0.1-10 μM, and can be a sodium fluoride solution, a potassium fluoride solution or a calcium fluoride solution.

[0030] Furthermore, in step 3, the laser wavelength emitted by the laser pen is 500-550 nm; and the filter is used to filter the laser wavelength of the laser pen.

[0031] In the present invention, the laser pen and filter can be screened and verified according to the selected fluorescent reagent.

[0032] In step 3, the mixed solution after incubation is added to the first cuvette, the fluorescent reagent is RhB with a concentration of 50 nM, which is added to the second cuvette, and the photograph taken includes the first cuvette and the second cuvette.

[0033] Furthermore, in step 4, the image is processed by Matlab software to obtain the G value of the image; the effective excitation area is the light column area formed by the laser beam passing through the solution in the cuvette.

[0034] Furthermore, the step 5 is specifically as follows:

[0035] The water sample to be tested was collected and filtered through a 0.45 μm pore size filter syringe, and then excess HCl was added to remove excess carbonate ions in the water, and then NaOH was added to adjust the pH to neutral.

[0036] The present invention uses the detection box as the device shell, which not only fixes the position of each device, but also creates a dark environment for detection to avoid interference from the external environment.

[0037] The present invention uses a commercially available laser pen as a light source. For example, a commercially available laser pen can emit a light beam with a wavelength of 532 nm. After passing through two optical lenses, a beam splitter and a reflector, the light beam is split into two parallel and perpendicular light beams that are irradiated by the laser pen before the optical lens, and then irradiated into the corresponding cuvette through the light transmission hole. The principle is as follows: Figure 2 As shown. A conical cylinder cover is designed and manufactured vertically above the cuvette to avoid the influence of ambient light and fix the distance between the mobile phone camera and the cuvette, and a smart phone fixing slot connected to the upper part of the conical cylinder for fixing the mobile phone. A shooting hole is opened at the bottom of the slot corresponding to the camera position of the mobile phone, and a hollow cylinder is threadedly connected to the hole at the upper part of the conical cylinder, and a filter is arranged inside the hollow cylinder. The internal components of the device are simple, without any cumbersome operation, and anyone can assemble it.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention discloses a portable device based on a smart phone, and is used for fluoride ion detection in water. The portable device of the present invention is used as a detection device to construct a standard linear curve of fluoride ions, and the smart phone is used to shoot and identify RGB values, so as to obtain a linear relationship between different concentrations of fluoride ions and G ratios. The water sample to be tested is detected by the portable device of the invention, and the fluoride ion concentration of the water sample can be quickly and accurately determined. The present invention reduces the demand for actual water sample detection conditions, takes the actual water sample to be tested as the analysis basis, realizes the fluoride ion determination of the actual water sample, and avoids the deviation of the detection result caused by the unstable light source power. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1A diagram showing power variation during use of a laser pen in the prior art; Figure 2 It is a schematic diagram of a portable detection device based on a smart phone of the present invention; Figure 3 This is a schematic diagram of the separate structures of the various parts of the portable detection device based on a smart phone of the present invention;

[0041] Figure 4 The structure of the portable detection device based on smart phone of the present invention is Figure 1 ;

[0042] Figure 5 The structure of the portable detection device based on smart phone of the present invention is Figure 2 ;

[0043] Figure 6 The structure of the portable detection device based on smart phone of the present invention is Figure 3 ;

[0044] Figure 7 The structure of the portable detection device based on smart phone of the present invention is Figure 4 ;

[0045] Figure 8 The structure of the portable detection device based on smart phone of the present invention is Figure 5 ;

[0046] Among them, 1 is a beam splitter, 2 is a reflector, 3 is a cuvette, 3-1 is a first cuvette, 3-2 is a second cuvette, 4 is a cover, 5 is a hollow cylinder, 6 is a conical cylinder cover, 7 is a smart phone fixing slot, 8 is a mobile phone camera shooting hole, 9 is a laser pen fixing cylinder, 10 is a detection box, 11 is a partition, 12 is a light-transmitting hole, 12-1 is a first light-transmitting hole, 12-2 is a second light-transmitting hole; 13 is an incident hole, 14 is a laser pen, 15 is a support frame, 16 is a positioning column, 16-1 is a first positioning column, 16-2 is a second positioning column, 17 is a sample slot, 17-1 is a first sample slot, 17-2 is a second sample slot, 18 is a beam splitter optical adjustment frame, 19 is a reflector optical adjustment frame;

[0047] Fig. 9 This is the ratio diagram of the power of the two laser beams of the laser pen laser passing through the beam splitter;

[0048] Fig.10 This is a picture of the sample area taken in step 4 of Example 2 of the present invention, with the reference on the right and the sample on the left;

[0049] Fig.11 for Fig.10 The effective excitation area image extracted from ;

[0050] Fig.12 It is the standard working curve diagram of different fluoride ion concentrations and G ratios;

[0051] Fig.13To measure different concentrations of RhB using the device of the embodiment, (a) the effect of different concentrations of RhB on R ratio, G ratio and B ratio; (b) the linear relationship between different concentrations of RhB and R ratio; (c) the linear relationship between different concentrations of RhB and G ratio; (d) the linear relationship between different concentrations of RhB and B ratio;

[0052] Fig.14 This is a picture of the time stability test of RhB using the equipment in Example 1;

[0053] Fig.15 (a) is a fluorescence spectrophotometer for measuring the fluorescence of RhB and establishing a linear relationship; (b) is a fluorescence spectrophotometer for measuring the fluorescence of RhB and establishing a linear relationship;

[0054] Fig.16 This is a picture of the selectivity and anti-interference of fluoride ion detection by MR;

[0055] Fig.17 This is a picture of the stability experiment of MR material in water. DETAILED DESCRIPTION

[0056] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0057] In the present invention, the materials and reagents used can be obtained from commercial sources unless otherwise specified. The optical lenses in the portable detection device based on a smart phone in the present invention are shown in Table 1 below.

[0058] Table 1

[0059]

[0060] The fluoride ion solution was prepared by the following method:

[0061] Accurately weigh 0.21 g of sodium fluoride, add ultrapure water to dissolve, and use a 500 mL volumetric flask to dilute to obtain a 0.01000M fluoride ion standard solution. Dilute the standard solution with ultrapure water to obtain standard working solutions with concentrations of 1000, 800, 500, 200, 100, 80, 60, 40, 20, 10, 5, and 1 μM, respectively. Continue to dilute the 10 μM standard working solution to obtain standard working solutions of fluoride ions with concentrations of 8, 4, 2, 1.5, 1, 0.5, 0.2, and 0.1 μM, respectively. Store the above solutions at room temperature in a sealed container away from light.

[0062] The present invention provides a method for detecting fluoride ions in water based on a smart phone, and specific embodiments are as follows.

[0063] Example 1

[0064] A portable detection device based on a smartphone, such as Figure 3-8 , including a beam splitter 1, a reflector 2, a cuvette 3, a cover 4, a hollow cylinder 5, a conical cylinder cover 6, a smart phone fixing slot 7, a mobile phone camera shooting hole 8, a laser pen fixing cylinder 9 and a detection box 10;

[0065] The detection box 10 is provided with a partition 11 for dividing the detection box 10 into a light mirror area and a sample area; the partition 11 is provided with light-transmitting holes 12, and the light-transmitting holes 12 include a first light-transmitting hole 12-1 and a second light-transmitting hole 12-2;

[0066] The optical mirror area is used to place the beam splitter 1 and the reflector 2, and the cover 4 is used to make the optical mirror area a dark room; the sample area is used to place the cuvette 3, and the conical tube cover 6 is used to make the sample area a dark room, and the cuvette 3 includes a first cuvette 3-1 and a second cuvette 3-2;

[0067] In the optical mirror area, an incident hole 13 is provided on the side wall of the detection box 10, and the laser pen fixing tube 9 is used to fix the laser pen 14 on the side wall of the detection box 10. The laser emitted by the laser pen 14 is irradiated onto the beam splitter 1 through the incident hole 13. The beam splitter 1 is used to split the laser into two laser beams with little difference in power and perpendicular to each other; one of the laser beams is irradiated onto the first cuvette 3-1 through the first light-transmitting hole 12-1, and the other laser beam is irradiated onto the reflector 2, and is reflected by the reflector 2 and then irradiated onto the second cuvette 3-2 through the second light-transmitting hole 12-2;

[0068] The top of the conical cylinder cover 6 is fixedly connected to the hollow cylinder 5. A filter (not shown) is arranged in the middle of the hollow cylinder. A smartphone fixing groove 7 is fixed on the top of the hollow cylinder 5 for fixing the smartphone. The smartphone fixing groove 7 has a hole at the connection position with the hollow cylinder 5, which is a shooting hole 8 for the mobile phone camera. The smartphone can be used to take pictures of the sample area through the shooting hole 8 of the mobile phone camera.

[0069] The detection box of the present invention is a dark box, the position of the light source is fixed by a laser pen fixing tube, and then a beam splitter and a reflector are set to split the laser into two beams with similar power, and the two beams are respectively irradiated into the sample cuvette and the reference cuvette, so that the two emit fluorescence synchronously, and then the two are photographed on the same photo by a mobile phone, which is convenient for subsequent analysis; and a filter is set to filter out stray light, ensure that the light in the photographed photo is all fluorescence, and improve the accuracy of the test. The internal components of the device of the present invention are simple, without any cumbersome operation, and easy to assemble.

[0070] Preferably, two positioning posts 16 are fixed to the bottom of the detection box 10, namely the first positioning post 16-1 and the second positioning post 16-2, and the top of the positioning post 16 is provided with a thread; the beam splitter 1 is fixed by the beam splitter optical adjustment frame 18, and the reflector 2 is fixed by the reflector optical adjustment frame 19, and the bottom of the beam splitter optical adjustment frame 18 and the reflector optical adjustment frame 19 are both provided with internal threads, which cooperate with the top threads of the positioning posts 16, and the beam splitter optical adjustment frame 18 and the reflector optical adjustment frame 19 are respectively fixed on the first positioning post 16-1 and the second positioning post 16-2; it is convenient to determine the fixed position of the optical lens during on-site installation. After the beam splitter and the reflector are installed, the focal position height of the lens is consistent with the incident height of the laser pen, thereby ensuring the accuracy of the test results.

[0071] Two sample slots 17 are provided at the bottom of the detection box 10, namely a first sample slot 17-1 and a second sample slot 17-2. The first sample slot 17-1 is used to fix the first cuvette 3-1, and the second sample slot 17-2 is used to fix the second cuvette 3-2; it is convenient to fix the position of the cuvette, and the liquid height in the cuvette 3 is higher than the position height of the light-transmitting hole 12, so as to ensure the accuracy of the test results.

[0072] Preferably, a support frame 15 is provided below the laser pen fixing tube 9 for supporting the laser pen fixing tube 14 ; during use, the laser pen 14 is inserted into the laser pen fixing tube 9 , and the laser emitted by the laser pen 14 will pass through the incident hole 13 to irradiate the beam splitter.

[0073] Furthermore, the smartphone fixing groove 7 is used to fix the smartphone. For different smartphones, a smartphone fixing groove 7 matching them can be prepared in advance; a smartphone fixing groove 7 with adjustable size can also be prepared by simple components such as springs to make it suitable for all smartphones.

[0074] Example 2

[0075] A method for detecting fluoride ions in water based on a smartphone, comprising:

[0076] Step 1: Prepare MOF material using AlCl3·6H2O and 2-aminoterephthalic acid as raw materials, and encapsulate the fluorescent reagent in MOF to obtain the new fluorescent material MR; specifically:

[0077] (11) 0.51 g AlCl3·6H2O, 0.56 g 2-aminoterephthalic acid and 30 mL DMF were added to a beaker and ultrasonically treated for 10 min. After being evenly mixed, they were added to a 100 mL reactor and heated in an oven at 130° for 72 h under static conditions. After heating, the yellow product was separated by centrifugation and washed three times with methanol and ethanol. The yellow product was then transferred to a vacuum drying oven, dried at 60°C overnight, and ground with quartz to obtain a yellow powder (MOF).

[0078] (12) Rhodamine B (15 mg) and MOF (100 mg) were placed in 50 mL of anhydrous ethanol, and mixed by ultrasonication for 5 min. The mixture was placed in a constant temperature oscillating box and oscillated for 12 h at 25 °C. After the oscillation, the mixture was centrifuged and repeatedly washed with ethanol and water (more than five times each) until the fluorescence intensity of the supernatant no longer changed. Finally, the collected MOF@RhB (MR) was placed in a vacuum drying oven, dried at 60 °C overnight, and ground in a quartz mortar to obtain a light red powder (MR).

[0079] Step 2: Prepare MR into a solution, mix it with the fluoride ion solution in a set ratio to form a mixed solution, and incubate it; specifically:

[0080] 3 mg of MR was evenly dispersed in 20 mL of ultrapure water (MR concentration was 0.15 mg / mL) by ultrasonic treatment; 3 mL of fluoride ion solution was mixed with 200 μL of MR solution and transferred to a water bath and incubated at 70 °C for 10 min; after the incubation was completed and cooled to room temperature, the measurement could be carried out;

[0081] Step 3: Place the incubated mixed solution into the portable detection device of Example 1, and use the fluorescent reagent as a reference; turn on the laser pen, and then use a smart phone to take a photo of the sample area; specifically:

[0082] In the portable detection device of Example 1, the wavelength of the laser emitted by the laser pen is 532nm; the wavelength filtered by the filter is 532nm;

[0083] Take 3 mL of the mixed solution after incubation and add it to the first cuvette, take 3 mL of 50 nM RhB and add it to the second cuvette, then turn on the laser pen and take a photo with a smartphone, as shown in Fig.10 ; Each concentration was measured 3 times and three photos were taken;

[0084] Step 4: Cut out the effective excitation area from the photograph (the effective excitation area is the position where the laser beam irradiates in the cuvette), such as Fig.11, and obtain the G values ​​in the RGB values ​​of the corresponding areas of the sample solution and the reference solution respectively; then calculate the ratio of the G value of the sample solution to the G value of the reference solution, recorded as the G ratio, and obtain the average G ratio of the area; specifically:

[0085] Save the captured valid area image to the specified folder and use Matlab software to write the following program:

[0086] =mread('file location\image name.jpg','jpg');

[0087] RGB_mean=mean(mean());

[0088] R_mean=RGB_mean(:,:,1);

[0089] G_mean=RGB_mean(:,:,2);

[0090] B_mean=RGB_mean(:,:,3);

[0091] By running the above program, the average G ratio calculation of each effective area image is completed, that is, the process of converting optical signals into electrical signals and finally into digital signals is completed;

[0092] Then, solutions with fluoride ion concentrations of 10 μM, 8 μM, 4 μM, 2 μM, 1.5 μM, 1 μM, 0.5 μM, 0.2 μM, 0.1 μM and 0 μM were mixed and incubated with 200 μL of MR solution, and photos were taken to calculate the fluoride ion concentrations of different concentrations. ; The results are shown in Table 2.

[0093] Table 2

[0094]

[0095] As shown in Table 2, when the fluoride ion concentration exceeds 2 μM, the G channel ratio does not change significantly and tends to be balanced. It can be seen that the G channel ratio has good linearity for fluoride ion solutions in the concentration range of 0.1-1.5 μM, and it can be obtained that the G channel ratio has good linearity for fluoride ion solutions in the range of 0.1000-1.500 μM F - The linear regression equation in the range is , R²=0.9948, with a good linear relationship, such as Fig.12 As shown;

[0096] Step 5: Collect the water sample to be tested, filter the water sample to be tested through a 0.45 μm pore size filter syringe to remove most of the impurities, add excess HCl to remove excess carbonate ions in the water, and then add NaOH, use a pH meter to adjust the pH of the water sample to neutral, and then based on the above steps S2-S4, determine the corresponding G ratio to be 1.9755, and substitute it into the above standard working curve to convert the fluoride ion concentration of the water sample to be tested to 0.5966 μmoL / L.

[0097] The linear standard working curve obtained was calculated to have a detection limit of 0.03350 μM. It can be found that the linear range is much lower than that of the direct fluorescence method, and the sensitivity to fluoride ions is increased by nearly 10 times, which allows the water sample to be diluted several times or even dozens of times when measuring the actual water sample, reducing the influence of other interfering ions in the water sample while ensuring that the detection of fluoride ions is not affected, which is impossible to do by direct fluorescence method.

[0098] To verify the beneficial effects of the method of the present invention, the inventors also conducted the following experiments.

[0099] 1. Light source stability evaluation

[0100] Fully charge the laser pen you purchased, then use it to test the laser power change within 30 minutes. Figure 1 As shown in the figure, during the 30 mn use of the laser pen, the laser power is not a stable output but fluctuates. When the battery is exhausted after being used for more than 30 mn, the laser power decreases rapidly.

[0101] By using the device of Example 1 of the present invention, the laser is divided into two beams, wherein the laser emitted by the laser pen is named the main beam, the laser reaching the cuvette after passing through the beam splitter is named beam 1, and the laser reaching the cuvette through the reflector is named beam 2. In order to verify that the power of the two laser beams is consistent at the same time, the power of the laser at beam 1 and beam 2 is measured at the same time and the ratio of the two powers is calculated, such as Fig. 9 As shown in the figure, it can be found that during the 30 mn continuous use of the laser pen, the ratio of the power of the two laser beams is always maintained near 1 with small fluctuations. Therefore, this experiment shows that the power of the lasers on beam 1 and beam 2 is basically the same at the same time, which meets the premise that the device eliminates the influence of laser power fluctuations on the experimental results.

[0102] 2. Selection of RGB channels

[0103] 100 μL of RhB with concentrations of 5, 10, 20, 30, 40, 50 and 60 nM was added to 3 mL of water to obtain RhB solutions with final concentrations of 0.16, 0.32, 0.64, 0.97, 1.29, 1.6 and 1.93 nM, respectively. These solutions were poured into cuvettes in turn and placed in the sample pool on the left side of the smartphone-based portable detection device; while in the sample pool on the right side, 100 μL of 30 nM RhB was added to 3 mL of water (final concentration 0.97 nM) as a reference. Each concentration was measured three times, three photos were taken, and the effective area was cut and the RGB average value was obtained. Fig.13 As shown, the obtained RGB value and the corresponding reference RGB value are matched one by one to calculate the R ratio ( )、G ratio( )、B ratio( ), R ratio linearity, G ratio linearity, and B ratio linearity were established with RhB concentration respectively.

[0104] Depend on Fig.13 It can be seen that different concentrations of RhB have a certain linear relationship with the R ratio and the G ratio, but no obvious linear relationship with the B ratio. This is because the spectral sensitivity of most smartphone cameras usually has a good response wavelength range of about 450-500 nm for the B channel, a good response wavelength range of about 570-600 nm for the R channel, and the best response wavelength range of about 500-600 nm for the G channel. The emission wavelength of RhB measured in this experiment is 578nm, which is within the wavelength range of the best response of the R and G channels. Therefore, when measuring RhB with a portable detection device based on a smartphone, the R channel and the G channel can be used as detection channels and linearity can be established. In addition, it can be found that the linear curve established through the R channel has a linear equation: , R²=0.9481; the linear curve established by the G channel, its linear equation is: , R²=0.9736. The slope and R² of the linear curve established through the G channel are greater than the slope and R² of the linear curve established through the R channel, which means that the linear curve of RhB established through the G channel will be more sensitive and accurate.

[0105] 3. Stability evaluation

[0106] The present invention uses an optical lens to change the light path, so that two laser beams act together on the sample pool and the ratio of the information carried by the two laser beams is calculated to solve the problem of power fluctuation of the laser emitted by the laser pen. In order to verify whether this method is stable for fluorescence detection of portable detection equipment based on smartphones, RhB solutions with a concentration of 40 nM are placed in the cuvettes on the left and right sides, the laser pen switch is turned on, and the smartphone is used to take photos of the sample pool through the filter at 0, 1, 2, 3, 4, 5, 7, 9, 11, 13, 15, and 20 minutes, and each group is measured three times. Then the image is processed to obtain Fig.14 The change of the ratio of the G channel of the cuvette images on both sides over time is shown. It can be found that despite the fluctuation of laser power, the result measured by the ratio method is stable and does not fluctuate significantly.

[0107] 4. Fluorescence measurement

[0108] In order to evaluate the fluorescence detection performance of the portable detection device based on a smartphone of the present invention, a fluorescence spectrophotometer and the portable detection device based on a smartphone of the present invention were used together to detect the prepared 60, 50, 40, 30, 20, 10 and 5 nM RhB standard solutions by fluorescence method, and the measurement results were compared, as shown in FIG. Fig.15 shown.

[0109] It can be found that Fig.15 (a) is the determination of RhB at different concentrations by fluorescence spectrophotometer, and a standard linear curve was established, and its linear equation is: , R²=0.9990, and the fluorescence spectrophotometer measurement results were used as the standard to evaluate the measurement performance of the portable detection device based on smartphones. When the portable detection device based on smartphones was used to measure the RhB with the same concentration gradient mentioned above, it was found that the G value in RGB of the 5 nM RhB measurement result exceeded 240, making it impossible to make a linear analysis under the above concentration gradient. Therefore, 100 μL of the above RhB with different concentrations was added to 3 mL of ultrapure water to obtain RhB solutions with final concentrations of 0.16, 0.32, 0.64, 0.97, 1.29, 1.61 and 1.93 nM after dilution 31 times, and portable measurements were performed, as shown in Figure 2. Fig.15 As shown in (b), a linear standard curve of RhB in the range of 0.16-1.93 nM was established, and its linear equation is: , R²=0.9925, which has a good linear relationship. However, RhB in this concentration range cannot be measured by a fluorescence spectrophotometer. It can be seen that the sensitivity of fluorescence detection of the portable detection device based on a smartphone is much greater than that of a fluorescence spectrophotometer and the measurement accuracy can still meet the actual measurement needs. This is because the light source used by the fluorescence spectrophotometer is a low-power xenon lamp, and its power is much lower than the laser power emitted by the laser pen, so that the device of the present invention can measure lower concentrations of RhB, but for the measurement of RhB in a large concentration range, it will result in reaching the upper limit of the RGB channel and unable to achieve accurate measurement of RhB. At this time, it only needs to be diluted to a certain extent;

[0110] A 34 nM RhB standard solution was selected, and the concentration was tested using a fluorescence spectrophotometer and the device of the present invention respectively; the concentration was calculated using the fluorescence spectrophotometer to be 33.96 nM; the RhB standard solution was diluted and measured using the device of the present invention, and the final concentration was 33.74 nM. The concentration obtained by the device and method of the present invention was not much different from that obtained by the fluorescence spectrophotometer.

[0111] 5. Research on selectivity, anti-interference and stability

[0112] In order to better confirm the central metal Al 3+ and free F in solution - The specific binding between fluoride and other ions achieves the specific destruction of MR, leading to the release of RhB in the gap. In this regard, the fluorescence response of other ions commonly found in water to MR was studied. In the experimental group, 3 mL of a 1:1 mixture of 80 μM fluoride ions and 1 mM other ions was measured, and in the control group, 3 mL of a 1:1 mixture of 1 mM other ions and ultrapure water was measured. Fig.16 As shown, the fluorescence responses of other ions to MR as well as F - The fluorescence response of the mixed solution mixed with other ions to MR. - The solution after MR fluorescence signal increased by more than 6 times, while other ions (NO3 - 、CO3 2- 、NO2 - 、SO4 2- 、HSO4 - 、S2O3 2- , Cl - Br - , - , Ca 2+ Mg 2+ , K + ) concentration is higher than F -The concentration is 12.5 times higher, but its fluorescence signal to MR is not much different from that to the solution without any ions. - After that, the fluorescence signal of MR was significantly enhanced. In summary, for common ions in water, it can be seen that MR is used for F - The detection has good selectivity and anti-interference.

[0113] Since MOF materials may collapse in water or be affected by water molecules, the materials in this experiment also need to consider whether the encapsulated RhB will leak in water. Fig.17 As shown in the figure, the prepared MR material was prepared into a 0.3 mg / mL aqueous solution for storage, and the background fluorescence signal of the MR solution and the addition of 40 μM F - The fluorescence signal after adding F was measured for one week. Before each measurement, the MR stock solution was ultrasonicated for 30 s to make it evenly dispersed before measurement. - The fluorescence signal after the test had almost no fluctuation within seven days. Therefore, it can be concluded that the MR material will not have the problem of material structure collapse and encapsulated RhB leakage in a short period of time. This result provides a strong guarantee for the material to be used for rapid on-site detection in the future.

[0114] 6. Evaluation of the accuracy of test results

[0115] Water samples were collected from the river inside and around the school. A total of 2 water samples were collected and measured using a fluorescence spectrophotometer (IC) and the device of Example 1 respectively. The water samples were fully shaken and mixed before measurement, and each water sample was measured three times. The results are shown in Tables 3-5.

[0116] Table 3

[0117]

[0118] Table 4

[0119]

[0120] Table 5

[0121]

[0122] It can be seen from Tables 3-5 that the fluoride ion concentration detected by the device and method of the present invention is slightly different from that by the IC method, which proves that the results of the determination of fluoride ions in water by the portable detection device assisted by the smartphone are reliable.

[0123] The above experiments have verified that the portable detection device based on a smart phone of the present invention can realize high-precision detection of fluoride ions in water, which is convenient and fast.

[0124] Example 3

[0125] In this embodiment, the MR concentration in step 2 is 0.3 mg / mL, the incubation condition is 60° C. for 60 min, and the other conditions are the same as in embodiment 1.

[0126] In order to further illustrate the beneficial effects of the present invention, the following comparative example was constructed.

[0127] Comparative Example 1

[0128] In this comparative example, AlCl3·6H2O was replaced with an equal amount of FeCl3·6H2O to prepare MOF material.

[0129] Comparative Example 2

[0130] In this comparative example, AlCl3·6H2O was replaced with an equal amount of zirconium chloride to prepare a MOF material.

[0131] Comparative Example 3

[0132] In this comparative example, AlCl3·6H2O was replaced with an equal amount of zinc chloride to prepare the MOF material.

[0133] Comparative Examples 1-3 replace AlCl3·6H2O with conventional raw materials for preparing MOF materials. The inventors found that the newly prepared MOF materials were unable to achieve a fluorescent response to fluoride ions, that is, the materials prepared in Comparative Examples 1-3 were unable to detect fluoride ions in water.

[0134] In summary, the portable detection device based on a smart phone of the present invention uses a laser pen as an excitation source, and the smart phone captures the emission signal of RhB released by it, and realizes the detection of F by using the ratio of the G channel in RGB. - The high-sensitivity detection has established linearity in the range of 0.1000-1.500 μM, which is more sensitive than traditional fluorescence spectrophotometer detection.

[0135] The above is a preferred embodiment of the present invention. For ordinary technicians in this technical field, making several improvements and modifications without departing from the principles of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A method for detecting fluoride ions in water based on a smart phone, characterized in that: include: Step 1: Prepare MOF material using AlCl3·6H2O and 2-aminoterephthalic acid as raw materials, and encapsulate the fluorescent reagent in MOF to obtain the new fluorescent material MR; Step 2: MR is prepared into a solution, mixed with a fluoride ion solution in a set ratio to form a mixed solution, and incubated; Step 3: Place the incubated mixed solution into a portable detection device and use the fluorescent reagent as a reference solution; Turn on the laser pointer and use your smartphone to take pictures of the mixture and the reference solution; Step 4: Cut out the effective excitation area from the photograph, and obtain the G value in the RGB values ​​of the corresponding areas of the sample solution and the reference solution respectively; then calculate the ratio of the G value of the sample solution to the G value of the reference solution, which is recorded as the G ratio; Sequentially take photos of fluoride ion mixed solutions with different concentrations, intercept the effective areas of each to identify the G value in the corresponding RGB value, calculate the G ratio, and establish a standard working curve with the fluoride ion concentration as the horizontal axis and the G ratio as the vertical axis; Step 5: After pre-treating the water sample to be tested, determine the corresponding G ratio according to the above steps 2 to 4, and convert the fluoride ion concentration of the water sample to be tested in combination with the standard working curve.

2. The detection method according to claim 1, characterized in that: The step 1 is specifically as follows: (11) AlCl3·6H2O, 2-aminoterephthalic acid and DMF were added to a beaker and ultrasonically mixed, then added to a reactor and heated in an oven at 130° for 72 h. After heating, the yellow product was separated by centrifugation, and yellow powder MOF was obtained by washing, drying and grinding. (12) Rhodamine B and MOF were placed in anhydrous ethanol and ultrasonically mixed. The mixture was placed in a constant temperature oscillating box and oscillated for more than 12 h. After the oscillation, the mixture was centrifuged and washed until the fluorescence intensity of the supernatant no longer changed. Finally, the product was dried to obtain a light red powder MR.

3. The detection method according to claim 2, characterized in that: The step 2 is specifically as follows: Disperse MR ultrasound evenly in ultrapure water to obtain a MR solution with a concentration of 0.3 mg / mL; mix 3 mL of fluoride ion solution and 200 μL of MR solution, transfer to a water bath and incubate at 70°C for 10 min; after the incubation is completed and cooled to room temperature, the measurement can be performed; The fluoride ion solution is a sodium fluoride solution, a potassium fluoride solution or a calcium fluoride solution with a fluoride ion concentration of 0.1-10 μM.

4. The detection method according to claim 3, characterized in that: In step 3, the laser pen emits a laser with a wavelength of 500-550 nm.

5. The detection method according to claim 4, characterized in that: In step 3, the fluorescent reagent is RhB, and the concentration is 10-50 nM.

6. The detection method according to claim 5, characterized in that: In step 4, the image is processed by Matlab software to obtain the G value of the effective excitation area; the effective excitation area is the light column area formed by the laser beam irradiating through the solution in the cuvette.

7. The detection method according to claim 6, characterized in that: The step 5 is specifically as follows: collecting a water sample to be tested, filtering it through a 0.45 μm pore size filter syringe, then adding excess HCl to remove carbonate ions in the water, and then adding NaOH to adjust the pH to neutral.

8. The detection method according to claim 1, characterized in that: In step 3, the portable detection device includes a beam splitter, a reflector, a cuvette, a cover, a hollow cylinder, a conical cylinder cover, a smartphone fixing slot, a mobile phone camera shooting hole, a laser pen fixing cylinder, a detection box and a laser pen; The detection box is provided with a partition plate for dividing the detection box into a light mirror area and a sample area; the partition plate is provided with light-transmitting holes, and the light-transmitting holes include a first light-transmitting hole and a second light-transmitting hole; The optical mirror area is used to place the beam splitter and the reflector, and the cover is used to make the optical mirror area a dark room; The sample area is used to place a cuvette, and the conical tube cover is used to make the sample area a dark room, and the cuvette includes a first cuvette and a second cuvette; In the optical mirror area, an incident hole is provided on the side wall of the detection box, the laser pen fixing tube is used to fix the laser pen on the side wall of the detection box, the laser emitted by the laser pen is irradiated onto the beam splitter through the incident hole, and the beam splitter is used to split the laser into two laser beams with the same power and parallel to each other; one laser beam is irradiated onto the first cuvette through the first light-transmitting hole, and the other laser beam is irradiated onto the reflector, and is reflected by the reflector and then irradiated onto the second cuvette through the second light-transmitting hole; The top of the conical cylinder cover is fixedly connected to the hollow cylinder, a filter is arranged in the middle of the hollow cylinder, the top of the hollow cylinder is fixed with the smart phone fixing groove, and a shooting hole for a mobile phone camera is arranged at the connection position between the smart phone fixing groove and the hollow cylinder.

9. The detection method according to claim 8, characterized in that: A support frame is provided below the laser pen fixing tube for supporting the laser pen fixing tube; The bottom of the detection box is provided with two positioning posts, namely a first positioning post and a second positioning post, and the top of the positioning post is provided with a thread; The beam splitter is fixed by a beam splitter optical adjustment frame, and the reflector is fixed by a reflector optical adjustment frame. The bottoms of the beam splitter optical adjustment frame and the reflector optical adjustment frame are both provided with internal threads, and the beam splitter optical adjustment frame and the reflector optical adjustment frame are respectively fixed on the first positioning column and the second positioning column; The bottom of the detection box is provided with two sample slots, namely a first sample slot and a second sample slot. The first sample slot is used to fix the first cuvette, and the second sample slot is used to fix the second cuvette.

Images