Method for rapidly detecting chloride ions in water body by using smart phone graphic colorimetric method

Abstract

The invention discloses a method for rapidly detecting chloride ions in a water body by using a smart phone graphic colorimetric method, which at least comprises the following steps: step 1, preparing a chlorine developing solution: measuring different volumes of Cl <-> standard solutions in different colorimetric tubes, then respectively adding a nitric acid solution, a mercuric thiocyanate solution and an ammonium ferric sulfate solution, mixing, and standing; diluting to a scale and carrying out a chromogenic reaction to obtain a chlorine chromogenic solution; 2, determining a chlorine content standard curve; 3, the chlorine content in the actual water body is measured, the color taking point is fixed by fixing the positions of the colorimetric tube and the smart phone, the accuracy of chlorine ion concentration measurement is guaranteed, when an actual water sample is detected, the recovery rate of the technical scheme disclosed by the invention is 98.3%-109.6%, the detection limit is 4.9 mg / L, and the quantitative analysis requirement of the chlorine ions in the water can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental detection, and specifically relates to a method for rapidly detecting chloride ions in water by smartphone graphic colorimetry. Background Art

[0002] The chloride ion content is one of the important indicators for evaluating water quality. An appropriate amount of chloride ions plays an indispensable role in maintaining the water ecosystem and industrial production processes. However, when the chloride ion content exceeds the normal range, a series of serious problems may be caused. In natural water bodies, too high a chloride ion concentration will disrupt the osmotic balance of aquatic organisms and affect their survival and reproduction; in domestic drinking water, the limit value of chloride ions is 250 mg / L. Excessive chloride ions will not only affect the taste, but long-term drinking may also pose a potential threat to the human cardiovascular system and kidneys; in the industrial field, the chloride ion emission limit for caustic soda and polyvinyl chloride industrial enterprises is 250 mg / L. Serious over-standard of chloride ions will cause obvious corrosion of steel bars, swelling, cracking and peeling of the concrete protective layer, greatly shortening its service life, increasing maintenance costs and safety hazards. Therefore, detecting the chloride ion content in water is of great significance for water quality monitoring, environmental assessment and industrial production control.

[0003] At present, the main detection methods for chloride ions include silver nitrate titration method, potentiometric titration method, spectrophotometry, ion chromatography method, etc. Although they have high accuracy and precision, they have disadvantages such as cumbersome operation, long analysis time, and the need for professional equipment and technical personnel. Among them, the silver nitrate titration method requires multiple titration operations, has limitations on the pH of the solution, and there is a certain subjectivity in endpoint judgment; the potentiometric titration method relies on a professional potentiometric titrator, which is expensive and has high maintenance costs; the ion chromatography method has complex equipment, strict requirements for sample pretreatment, and a long analysis cycle, making it difficult to meet the needs of on-site rapid detection. In the face of sudden water pollution incidents, large-scale water quality censuses or real-time monitoring on industrial production lines, the limitations of these traditional methods become more prominent.

[0004] With the popularization of smartphones and the rapid development of image processing technology, smartphone graphic colorimetry has emerged as a new detection technology. Smartphones have powerful image acquisition and processing capabilities. Combining with the principle of colorimetric analysis, they can achieve rapid determination of chloride ions in water. Smartphone graphic colorimetry (Digital Image Colorimetry, DIC) uses a specific color reagent to react with chloride ions to produce a color reaction. By taking a picture of the colored solution with a smartphone and using image processing software to extract and analyze the color characteristics of the image, a quantitative relationship between the color parameters and the chloride ion concentration is established.

[0005] CN119290867A discloses a method for determining calcium and magnesium in environmental water bodies by smartphone graphic colorimetry. This method can quickly detect the content of calcium and magnesium ions in water and meet the needs of on-site rapid detection. However, this method is not applicable to the detection of chloride ions in water bodies. Therefore, this application discloses a method for quickly detecting chloride ions in water bodies by smartphone graphic colorimetry. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method for quickly detecting chloride ions in water bodies by smartphone graphic colorimetry, which is used to solve the problems of cumbersome detection operation, long analysis time, high professional requirements, expensive equipment for detecting chloride ions in existing water bodies, and inability to conduct real-time monitoring of industrial / domestic sewage.

[0007] To achieve the above object, the technical solution adopted by the present invention is: A method for quickly detecting chloride ions in water bodies by smartphone graphic colorimetry, which at least includes the following steps:

[0008] Step 1, Preparation of chlorine color-developing solution: Measure different volumes of Cl - standard solution into different colorimetric tubes, then add nitric acid solution, mercuric thiocyanate solution, and ammonium ferric sulfate solution respectively, mix them, and dilute to the scale for color-developing reaction to obtain chlorine color-developing solution;

[0009] Step 2, Determination of chlorine content standard curve: Place the colorimetric tubes containing the chlorine color-developing solution obtained in Step 1 and the RGB supplementary light in a 3D printed light-shielding container, turn on the light source, take and save images with a smartphone, use color-picking software to read the R, G, and B values of the photo of the chlorine color-developing solution 3 times, take the average value, and perform data processing. Respectively establish the relationship curves between the digital signal values of the R, G, and B channels and different concentrations, and fit them into a standard curve;

[0010] Step 3, Determination of chlorine content in actual water bodies: Collect the water sample to be tested and measure it into a colorimetric tube, then add nitric acid solution, mercuric thiocyanate solution, and ammonium ferric sulfate solution, dilute to the scale, conduct a color-developing reaction, turn on the light source, take and save images with a smartphone, use color-picking software to read the B value of the photo of the chlorine color-developing solution 3 times, take the average value, and perform data processing. Substitute this data into the standard curve in Step 2 to obtain the content of chloride ions in the actual water body.

[0011] Optionally, the volume of the Cl - standard solution measured in Step 1 is 0, 0.2, 0.4, 0.6, 0.8, 1.0 mL.

[0012] Optionally, the volume ratio of the nitric acid solution, mercuric thiocyanate solution, and ferric sulfate solution is 0.4:1.6:1.2.

[0013] Optionally, the conditions of the color-developing reaction are as follows:

[0014] The temperature of the color reaction is 20 - 30 °C;

[0015] The time of the color reaction is 30 - 45 min.

[0016] Optionally, the colorimetric tube containing the chlorine color solution described in step 2 is fixed on one side inside the 3D printed light - proof container and closely attached to the middle baffle. Optionally, the smartphone is fixed on one side outside the 3D printed light - proof container, and the camera of the smartphone is focused on the fixed position, and the fixed position is near the bottom of the colorimetric tube.

[0017] Optionally, the model of the smartphone described in step 2 is at least one of OPPO Reno10, Huawei P60 Pro, and VIVO S18 Pro.

[0018] Optionally, the color - picking software is Color Grab.

[0019] Optionally, the water sample to be measured is at least one of tap water, lake water, river water, and sewage.

[0020] Optionally, the concentrations of SO4 2- , NO 3- , Mg 2+ , Ca 2+ , F - in the water sample to be measured are lower than 200 mg / L.

[0021] Optionally, the detection limit of the method is 4.9 mg / L, and the recovery rate is 98.3 - 109.6%.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The color - developing agent adopted in this application uses chloride ions to react with mercury thiocyanate to displace thiocyanate ions, and the thiocyanate ions then react with ferric ions to form a red ferric thiocyanate complex. The reaction formula is shown in Formula 1:

[0024] Hg(SCN)2 + 2CI - = HgCI2 + 2SCN - ; 3SCN - + Fe 3+ = Fe(SCN)3

[0025] Formula 1.

[0026] (2) By fixing the positions of the colorimetric tubes and the smartphones and fixing the color sampling points, the present application ensures the accuracy of chloride ion concentration measurement. When detecting actual water samples, the recovery rate of this method is 98.3% - 109.6%, and the detection limit is 4.9 mg / L, which can meet the requirements of quantitative analysis of chloride ions in water. Compared with the traditional spectrophotometry, the smartphone graphic colorimetry method does not require complex instrument equipment and professional operation skills. Only need to use a smartphone to take a colorimetric image and combine with image processing software to complete quantitative analysis, which greatly reduces the detection cost and time, and at the same time maintains high measurement accuracy and repeatability, indicating that this method has good anti-interference ability and practical application value in complex matrices, especially suitable for grass-roots detection institutions, environmental monitoring sites and areas with limited resources. Description of the Drawings

[0027] Figure 1 It is the operation interface of the ColorGrab software adopted in the embodiment of the present application;

[0028] Figure 2 It is the standard curve graph for measuring the chloride ion concentration in water under different digital signal values of the present application;

[0029] Figure 3 It is the standard curve graph for measuring the chloride ion concentration in water under different light irradiations of the present application;

[0030] Figure 4 It is the standard curve graph for measuring the chloride ion concentration in water using different brands of mobile phones of the present application;

[0031] Figure 5 It is the comparison graph of the linear correlation between the standard curve graph measured by the smartphone graphic colorimetry method of the present application and the ultraviolet spectrophotometer. Detailed Embodiment

[0032] In order to enable those skilled in the art to better understand the technical solution, the present application will be described in detail below in combination with the embodiments. The description of this part is only exemplary and understandable, and has no limiting effect on the protection scope of the present invention.

[0033] The specific working principle of the present application: Utilize the reaction of chloride ions with mercury thiocyanate to displace thiocyanate ions, and then the thiocyanate ions react with ferric ions to generate a red ferric thiocyanate complex. The reaction formula is shown in Formula 1:

[0034] Hg(SCN)2 + 2CI - = HgCI2 + 2SCN - ; 3SCN - + Fe 3+ = Fe(SCN)3

[0035] Formula 1.

[0036] Cl in the following examples - standard solution, SO4 2- ion standard solution, NO3 - ion standard solution, Ca 2+ standard solution, Mg 2+ standard solution, Na + standard solution, F - The standard solutions above are all from the National Nonferrous Metals and Electronic Materials Analysis Co., Ltd., c = 1000 μg / mL; ammonium ferrous sulfate solution (30 g / L): Dissolve 150 g of NH4Fe(SO4)2·12H2O in water, add 150 mL of HNO3, and prepare a 500 mL solution; saturated mercuric thiocyanate solution (3 g / L): Dissolve 1.5 g of Hg(SCN)2 in 500 mL of absolute ethanol, ultrasonically oscillate to dissolve and filter, and store in a brown bottle;

[0037] The models of smartphones used in the following examples are OPPO Reno10, Huawei P60 Pro, and VIVO S18 Pro; the LE204E electronic balance is used for weighing in the following examples; the UV-1800PC visible light spectrophotometer is used to measure the absorbance of the solution; 3D printed light-tight containers, RGB fill lights, diffuser plates, colorimetric tubes (10 mL), etc. are used for experimental tests.

[0038] Use of the smartphone Color Grab color picker software in the following examples: Place the RGB fill light in the 3D printed light-tight container. The light of different colors irradiates the colorimetric tube containing the chlorine color-developing solution through the diffuser plate. Place the smartphone and the colorimetric tube in fixed positions. Open the color picker software Color Grab, adjust the light sensitivity, fix the focus on a certain place of the colorimetric tube to prevent errors caused by inconsistent positions, take a photo sample of the colorimetric tube, extract the RGB channel signal values of the chlorine color-developing solution, record the data and establish a curve. The colorimetric tube containing the chlorine color-developing solution should be fixed on one side of the 3D printed light-tight container and close to the middle baffle. The smartphone is fixed at one end outside the 3D printed light-tight container, and the focus of the camera needs to be aligned with the fixed position, which should be close to the bottom of the colorimetric tube (as Figure 1 shown), read multiple groups of RGB channel signal values, so as to obtain the accurate sample concentration.

[0039] Example 1

[0040] A method for determining calcium and magnesium in environmental water by smartphone graphic colorimetry, comprising the following steps:

[0041] Step 1. Preparation of chlorine color-developing solution: Respectively pipette 0, 0.2, 0.4, 0.6, 0.8, 1.0 mL of 100 mg / L Cl⁻ standard solution into 10-mL colorimetric tubes. Then, successively add 0.4 mL of nitric acid solution (volume ratio of nitric acid to water is 1:1), 1.6 mL of saturated mercuric thiocyanate solution with a concentration of 3 g / L, and 1.2 mL of ammonium ferric sulfate solution with a concentration of 30 g / L. Dilute with water to the scale, shake well, and let stand for 30 min to obtain the chlorine color-developing solution. Measure its absorbance at a wavelength of 455 nm.

[0042] Step 2. Determination of chloride ion standard curve: Put the chlorine color-developing solution obtained in Step 1 into a 3D-printed light-shielding container. Use a smartphone to collect images. Use the mobile phone application Color Grab to read the R, G, B values of the chlorine color-developing solution 3 times, take the average value, and perform data processing. Respectively establish the relationship curves between the digital signal values of the R, G, B channels and different concentrations, and fit them into a standard curve.

[0043] Step 3. Determination of chlorine content in actual water samples: Collect the water samples to be tested, measure 1 mL into a colorimetric tube, then add 0.4 mL of nitric acid solution (volume ratio of nitric acid to water is 1:1), 1.6 mL of mercuric thiocyanate solution with a concentration of 3 g / L, and 1.2 mL of ammonium ferric sulfate solution with a concentration of 30 g / L. Dilute to the scale for color development reaction. Turn on the light source, use a smartphone to take and save an image, use the Color Grab color-picking software of OPPO Reno10 mobile phone to read the B value of the photo of the chlorine color-developing solution 3 times, take the average value, and perform data processing. Substitute this data into the standard curve in Step 2 to obtain the chloride ion content in the actual water body.

[0044] The standard curves of chlorine content measured at different digital signal values of channels in the above examples are as Figure 2 shown. As Figure 2 can be seen, among the R, G, B values obtained by the color-picking software Color Grab, the B value changes the most; Taking the chlorine concentrations of 0 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 10 mg / L as the abscissa and the R, G, B channel values as the ordinate to plot a scatter curve as shown in Figure 2 . Among them, as the chlorine concentration gradually increases, the fitting degree between the R channel and the standard solution concentration is the best. The linear equation of chlorine content is y = -3.3857x + 200.1, and the highest linear correlation coefficient is R² = 0.997. Therefore, the R channel value is selected as the detection digital channel of this method.

[0045] To verify the reliability of this method, 10 mL of ultrapure water was taken and repeatedly measured (10 times in total) under the same experimental conditions, and the standard deviation (S) of the digital signal value of the R channel was calculated. Substituting the measured values into the above standard curve equation of y = -3.3857x + 200.1, the method detection limit calculated was 4.9 mg / L. This indicates that this method can effectively detect the chlorine content in the low concentration range and is suitable for the rapid and accurate determination of the chlorine content.

[0046] To verify the accuracy of this method, the measurement results were compared and analyzed with the test results of the spectrophotometer. The specific test results are as Figure 5 shown. The results show that the linear correlation coefficient R 2 = 0.997 measured by the smartphone graphic colorimetry method is almost exactly the same as the linear correlation coefficient R 2 = 0.9994 measured by the ultraviolet spectrophotometry method, indicating that the smartphone graphic colorimetry method has high accuracy in the determination of the chlorine content.

[0047] Example 2

[0048] The difference between this example and Example 1 is that different light sources are used. To verify the influence of light of different wavelengths on the detection results of the color reaction, since there are differences in the uniformity of lights of different colors, white light, light blue light, and green light were respectively used to irradiate the chlorine color development solution, and the images were captured with a smartphone. The Color Grab color extraction software of the OPPO Reno10 mobile phone was used to read the B value of the chlorine color development solution photo 3 times, and the average value was taken. The test results are as Figure 3 shown. The results show that the fitting degree of the chlorine content measured using white light is significantly higher than that of other colors. Since white light has a wider spectral range and provides more uniform illumination conditions, it can reduce the shadow and reflection interference in the image, while a light source with a single wavelength may produce strong reflection or absorption under specific conditions, affecting the uniformity of the image. To reduce the detection error caused by the single wavelength of the light source, white light was selected for irradiation as the light source of this method.

[0049] Example 3

[0050] The difference between this example and Examples 1 and 2 is that different models of smartphones are used. Since there are differences in the performance of the cameras of different models of smartphones, their light sensor accuracies are different, the color extraction effects are different, and the obtained RGB values are also different. Therefore, to verify the applicability and accuracy of the method, OPPO Reno10, Huawei P60 Pro, and VIVO S18 Pro were respectively used to take pictures and save the chlorine color development solution. After color extraction with the Color Grab software, a linear relationship diagram of the B channel and the chlorine solution concentration was drawn. The results are as Figure 4As shown, the linear equation of the chlorine content measured by the three mobile phones shows that for OPPO Reno10, it is y = -3.3857x + 200.1, and the linear correlation coefficient is R2 = 0.997; for Huawei P60Pro, it is y = -4.5429x + 248.38, and the linear correlation coefficient is R2 = 0.9926; for VIVO S18Pro, it is y = -6.0857x + 223.76, and the linear correlation coefficient is R2 = 0.9958. The correlation coefficients of the calibration curves fitted by the above mobile phones are all greater than 0.99, meeting the requirements for rapid determination of chloride ions. Although the B-channel digital signal values for color processing of different models of smart phones are different, they still maintain a good linear correlation with the chlorine content, indicating the applicability of this method. Since the OPPO Reno10 has the highest linear correlation coefficient and the highest accuracy in the measurement results, OPPO Reno10 is selected as the experimental machine for this method.

[0051] Example 4

[0052] To test the influence of different interfering ions on the determination of chlorine content by smartphone graphic colorimetry, six ions that may interfere with the determination of chlorine content in water bodies are selected in this example: including NO3 - , SO4 2- , Mg 2 +, Ca 2 + and F - as interfering ions. Different concentration solutions are prepared using standard stock solutions for determination to test the anti-interference ability of this method in the presence of the above anions. The test results of chlorine content are shown in Table 1. The determination results show that when high concentrations (200 mg / L) of different interfering ions (sulfate ions, nitrate ions, magnesium ions, calcium ions, and fluoride ions) are present, the influence on the recovery rate of chlorine content determination is small. Specifically, when the chlorine content is 4 mg / L, the recovery rate is between 105.57 ± 3.42% and 119.96 ± 5.92%; when the chlorine content is 10 mg / L, the recovery rate is between 94.04 ± 1.4% and 102.68 ± 1.4%. This indicates that the adopted determination method has good accuracy and anti-interference ability, can effectively cope with the determination of chlorine content in complex matrices, and the influence of each ion on the determination of chlorine content is small. Therefore, the method of this application is applicable to the determination of chlorine content in water bodies with concentrations of NO3 - , SO4 2- , Mg 2 +, Ca 2 +, K + , Mn 2+ , Fe 3+ , Zn 2+ , and F - lower than 200 mg / L.

[0053] Table 1 Recovery rate determination in the presence of interfering ions

[0054]

[0055]

[0056] Example 5

[0057] To further verify the accuracy and reliability of the method disclosed in this application, two standard samples with standard values of 150 mg / L and 45 mg / L were selected. The expanded uncertainty of the 150 mg / L standard sample is 5 mg / L, and the expanded uncertainty of the 45 mg / L standard sample is 1.5 mg / L. The measurement results are shown in Table 2. The measurement results of both concentrations are within their respective expanded uncertainty ranges. Thus, it can be seen that the smartphone digital graphic colorimetry has sufficient accuracy and reliability in practical applications.

[0058] Table 2 Spike recovery rate of chlorine content in reference materials

[0059]

[0060] Example 6

[0061] To verify the practicability of the method disclosed in this application, the chloride ion content in three actual water samples (tap water, river water, and lake water) was determined on-site. All three water samples were measured on the day of collection. Among them, the tap water was collected from Room 364, Building 2 of Yuelu Mountain Laboratory (latitude 28°11′13″, longitude 113°4′14″), the lake water was collected from the lake near the Lover's Slope of Hunan Agricultural University (latitude 28°11′10″, longitude 113°4′27″), and the river water was collected from the Liuyang River in the riverside section (latitude 28°10′38″, longitude 113°4′45″). After diluting the collected water samples by 4 times for the color reaction, the spike recovery rate of the chlorine content was measured by digital image colorimetry. Each water sample was measured three times and the average value was taken. The results are shown in Table 3. The experimental results show that the digital image colorimetry still has good applicability in the analysis of real water samples, providing reliable technical support for on-site rapid analysis.

[0062] Table 3 Chlorine content and spike recovery rate in actual water samples

[0063]

[0064] To further verify the practicability of the method disclosed in this application, on-site measurements need to be carried out using the influent of industrial sewage, the effluent of industrial sewage, the influent of domestic sewage, and the effluent of domestic sewage; the industrial sewage is collected from the industrial park sewage treatment plant, and the domestic sewage is taken from rural domestic sewage; to reduce the interference of complex components in the sewage on the test results, all the collected sewage water samples are diluted. Among them, the effluent of rural domestic sewage is diluted 10 times, and other water samples are diluted 20 times, and then a color reaction is carried out. Each sewage water sample is measured in parallel three times to effectively reduce experimental errors, and the average value is taken as the final measurement result. The specific test results are shown in Table 4.

[0065] Table 4

[0066]

[0067] It should be noted that in this article, the terms: including, containing and any other variants are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to this process, method, article or device. Specific examples are used in this article to elaborate on the principle and implementation mode of the technical solution of the present invention. The description of the above examples is only used to help understand the method of the present invention and its core idea. The above is only the preferred implementation mode of the present invention. It should be pointed out that due to the limited nature of written expression and the objectively infinite specific structures, for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements, refinements or changes can also be made, or the above technical features can be combined in an appropriate manner; these improvements, refinements, changes or combinations, or directly applying the concept and technical solution of the present invention to other occasions without improvement, should all be regarded as the protection scope of the present invention.

Claims

1. A method for rapidly detecting chloride ions in water by graphic colorimetry of a smart phone, characterized in that, At least include the following steps: Step 1. Preparation of chlorine color-developing solution: Measure different volumes of Cl - standard solution into different colorimetric tubes, then add nitric acid solution, mercuric thiocyanate solution, and ammonium ferric sulfate solution respectively and mix them, dilute to the mark for color-developing reaction to obtain chlorine color-developing solution; Step 2, determination of chlorine content standard curve: Place the colorimetric tube containing the chlorine color-developing solution obtained in Step 1 and the RGB supplementary light in a 3D printed light-shielding container. Turn on the light source, take and save an image with a smartphone, use color picker software to read the R, G, and B values of the chlorine color-developing solution photo 3 times, take the average value, and perform data processing. Respectively establish the relationship curves between the digital signal values of the R, G, and B channels and different concentrations, and fit them into a standard curve; Step 3, determination of chlorine content in actual water body: Collect the water sample to be measured and measure it into a colorimetric tube. Then add nitric acid solution, mercuric thiocyanate solution, and ammonium ferric sulfate solution, dilute to the scale, carry out a color reaction. Turn on the light source, take and save an image with a smartphone, use color picker software to read the B value of the chlorine color-developing solution photo 3 times, take the average value, and perform data processing. Substitute this data into the standard curve in Step 2 to obtain the content of chloride ions in the actual water body.

2. The method for rapidly detecting chloride ions in water by graphic colorimetry of a smart phone according to claim 1, characterized in that, The volume of the Cl standard solution taken in Step 1 - is 0, 0.2, 0.4, 0.6, 0.8, 1.0 mL.

3. A method for rapidly detecting chloride ions in water by graphic colorimetry of a smart phone according to claim 1, characterized in that, The volume ratio of the nitric acid solution, mercuric thiocyanate solution, and ferric sulfate solution is 0.4:1.6:1.

2.

4. A method for rapidly detecting chloride ions in water by smartphone graphic colorimetry according to claim 1, characterized in that, The conditions of the color reaction are as follows: The temperature of the color reaction is 20 - 30 °C; The time of the color reaction is 30 - 45 min.

5. A method for rapidly detecting chloride ions in water by smartphone graphic colorimetry according to claim 1, characterized in that, Fix the colorimetric tube containing the chlorine color-developing solution described in Step 2 on one side inside the 3D printed light-shielding container and closely attach it to the middle baffle.

6. A method for rapidly detecting chloride ions in water by graphic colorimetry of a smart phone according to claim 5, characterized in that, Fix the smartphone on one side outside the 3D printed light-shielding container so that the camera of the smartphone focuses on the fixed position, and the fixed position is near the bottom of the colorimetric tube.

7. A method for rapidly detecting chloride ions in water by graphic colorimetry of a smart phone according to claim 1, characterized in that, The model of the smartphone described in Step 2 is at least one of OPPO Reno10, Huawei P60 Pro, and VIVO S18 Pro.

8. A method for rapidly detecting chloride ions in water by graphic colorimetry of a smart phone according to claim 1, characterized in that, The color picker software is Color Grab.

9. A method for rapidly detecting chloride ions in water by graphic colorimetry of a smart phone according to claim 1, characterized in that, The water sample to be measured is at least one of tap water, lake water, river water, and sewage; Preferably, the concentrations of SO4 2- , NO 3- , Mg 2+ , Ca 2+ , F - in the water sample to be measured are lower than 200 mg / L.

10. A method for rapidly detecting chloride ions in water by smartphone graphic colorimetry according to claim 1, characterized in that, The detection limit of the method is 4.9 mg / L, and the recovery rate is 98.3 - 109.6%.

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