Method for measuring calcium and magnesium in environmental water body by using smart phone graphic colorimetric method

Abstract

The invention discloses a method for measuring calcium and magnesium in an environmental water body by using a smart phone graphic colorimetric method, which belongs to the technical field of environmental monitoring and comprises the following steps: measuring a calcium and magnesium total amount standard curve, measuring a magnesium content standard curve and measuring the total amount of calcium and magnesium in an actual water sample. On the basis of a smart phone colorimetric method, water collection sampling, mixed reaction and photographing measurement are performed, and the test time of one sample can be controlled to be 10 min. The method is rapid, accurate and high in sensitivity, can be used for real-time field in-situ determination, and meets the requirements of rapid in-situ quantitative analysis and determination of an environmental water sample.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental monitoring, and specifically relates to a method for determining calcium and magnesium in environmental water using a smart phone graphic colorimetry method. Background Art

[0002] The content of calcium and magnesium ions in water is one of the important components of water hardness. Its content directly affects the quality of water. Therefore, the detection of calcium and magnesium ion content is not only an important item in water quality detection, but also an important indicator for judging the quality of water and water body. Researchers divide water into soft water, medium hard water, hard water and extremely hard water according to the content of calcium and magnesium ions in water from small to large. The detailed classification of water quality is because long-term drinking of water with too high hardness is not good for human health. It can damage the skin and cause aging, and even cause lesions in blood vessels, nerves and other systems. Therefore, the detection of calcium and magnesium ions in water has always been a hot topic discussed by many researchers. Because the two have similar properties, they interfere with each other during testing and often coexist, which brings certain difficulties to analysis.

[0003] At present, there are many methods for detecting calcium and magnesium ions, mainly including the following: titration, spectrophotometry, ion chromatography (IC), atomic absorption spectroscopy (AAS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The traditional titration method mainly refers to EDTA titration, which is based on the principle that in an alkaline solution, Ca 2+ Mg 2+ It forms a red complex with chrome black T and is titrated with EDTA standard titration solution. When the chrome black T indicator is replaced by EDTA, the solution turns blue, which is the end point. This method is greatly affected by human factors. The judgment of the titration end point varies depending on personal experience and color sensitivity. It is also easily interfered by other ions in water. The operation process is complicated and has high requirements for the color change range of the indicator.

[0004] Spectrophotometry is a method of using a color developer to color calcium and magnesium ions and measure their absorbance at a specific wavelength. Spectrophotometry has good reproducibility and precision, but its dependence on instruments is not conducive to rapid on-site determination. Ion chromatography is a method of continuously separating, qualitatively and quantitatively analyzing multiple coexisting ions by utilizing the different exchange capacities of the separated substances on ion exchange resins. Ion chromatography can continuously measure water samples and measure the concentrations of calcium and magnesium ions at the same time with one injection, but the instrument is also more cumbersome and the measurement process is more complicated.

[0005] Atomic absorption spectrometry is based on the emission of a characteristic line of light of a certain intensity and wavelength from a hollow cathode lamp of the element to be measured. When it passes through the ground state atomic vapor containing the element to be measured, the atomic vapor absorbs the light of this wavelength. The light of the characteristic line that is not absorbed is split by a monochromator and irradiated onto a photodetector for detection. The content of the element to be measured in the sample can be measured based on the degree of absorption of the characteristic line intensity.

[0006] The principle of ICP-OES is to process the sample into a solution and then introduce it into the plasma torch in the form of an aerosol. The sample is evaporated and excited, emitting light with characteristic wavelengths of the elements it contains. By measuring the unique spectral lines and intensities of each element and comparing them with the standard solution, the type and content of the elements contained in the sample can be determined.

[0007] Titration is laborious and has a large detection increment. In addition to titration, other methods are expensive and the process is complicated. Optical chemical sensors and ion selective electrodes have good detection limits, but often have problems such as long response time and short life. Therefore, finding a fast, economical and accurate measurement method is of great significance to ensure drinking water safety and evaluate water quality.

[0008] Recently, smartphones have been widely used as a detection tool in the fields of chemistry and medicine due to their powerful functions and popularity in modern society. With high-resolution cameras, wireless connectivity, and fast network communication capabilities, smartphones are portable accessories for on-site measurements and point tests, such as gas identification, colorimetric analysis, and cell counting systems.

[0009] Many domestic researchers have used smartphone graphic colorimetry to conduct extensive research and application in the field of environmental monitoring. Chen Hong et al. used the histogram peak grayscale as the threshold for image segmentation based on the RGB distribution characteristics of sediment particle images to determine the particle size of sediment particles; Cai Lu et al. successfully established a method based on smartphones and homemade colorimetric devices for rapid determination of ammonia nitrogen in water. This study achieved effective detection of ammonia nitrogen by optimizing the reaction conditions, showing the application potential of smartphones in water quality monitoring. Zhang Yunli et al. used image graying to process the depth image of the tip of corn kernels and compared corn varieties. The study investigated the influence of factors such as color development conditions and shooting distance, and verified the universality of different models of smartphones. The results showed that this method is suitable for the rapid determination of steroid hormone content. Jin Chao et al. used a digital image colorimetry method constructed by a smartphone and a small wooden box to complete the rapid detection of hexavalent chromium concentration in water. The method has a good linear range and reproducibility, proving its reliability and accuracy. Wang Jiahui et al. applied the image colorimetry method to the determination of the mass concentration of petroleum substances dissolved in organic solvents, and used the Euclidean distance mathematical model derived from RGB values ​​to calculate the mass concentration of petroleum substances. Zhang Anliang developed a heavy ion detection application system for smartphones on the Android operating system. The system improves the test accuracy and realizes the digital measurement of copper ion concentration through a self-made optical path system and compensation algorithm.

[0010] The existing smartphone graphic colorimetry is easily affected by lighting conditions and camera parameters, which limits its applicability in a variety of scenarios. In particular, in the detection of complex water sample components, different interfering ions have a greater impact on the determination of calcium and magnesium concentrations in the water environment. The traditional calcium and magnesium ion detection method is complicated and time-consuming, and is not convenient for rapid on-site determination. In addition, under different lighting conditions, the color difference between the standard color block image taken by the smartphone and the standard value is large, which affects the accuracy of the colorimetry. Summary of the invention

[0011] In view of the above problems, the present invention provides a method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method. Based on the smartphone colorimetric method, water collection sampling, mixed reaction, and photo measurement, the test time of a sample can be controlled within 10 minutes. The method is fast, accurate, and highly sensitive, and can be measured on-site in real time, meeting the requirements for rapid in-situ quantitative analysis of environmental water samples.

[0012] To achieve the above object, the technical solution adopted by the present invention is:

[0013] A method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method comprises the following steps:

[0014] Step 1, determination of the total calcium and magnesium standard curve: Mix the calcium ion standard solution and the magnesium ion standard solution in equal volumes, then dilute them into different concentrations of calcium and magnesium ion standard solutions, respectively measure them into colorimetric tubes, and then add acid chrome blue K solution, NH 3 -NH 4 Cl buffer solution was mixed to obtain a color solution, which was diluted to the scale for color development reaction. After color development for 5-10 min at room temperature, an image was taken with a mobile phone in a 3D printed light-proof container with the light source turned on. The R value of the color solution photo was read 3 times using a mobile phone application software, and the average value was taken. The data was processed to establish a relationship curve between the digital signal value of the R channel and different concentrations, and fitted into a standard curve;

[0015] Step 2, determination of magnesium content standard curve: dilute the magnesium ion standard solution, then measure different volumes of magnesium ion standard solution, put them into colorimetric tubes, and then add ammonium oxalate, triethanolamine, ascorbic acid, acid chrome blue K ethanol solution, NH 3 -NH 4 Cl buffer solution, diluted to the scale, color development reaction, color development at room temperature for 5-10 minutes, use a mobile phone to take and save images in a 3D printed light-proof container with the light source turned on, use the mobile phone application software to read the R value of the color development solution photo 3 times, take the average value, and perform data processing to establish the relationship curve between the digital signal value of the R channel and different concentrations, and fit it into a standard curve;

[0016] Step 3: Determination of the total amount of calcium and magnesium in the actual water sample: Collect the water sample to be tested, measure it into a colorimetric tube, and then add acid chrome blue K solution, NH 3 -NH 4 Cl buffer solution is mixed to obtain a color solution, which is diluted to the scale for color development reaction. After color development at room temperature for 5-10 minutes, an image is taken with a mobile phone in a 3D printed light-proof container with the light source turned on. The R value of the color solution photo is read 3 times using a mobile phone application software, and the average value is taken and data processing is performed. The data is then brought into the standard curve in the step to obtain the total amount of calcium and magnesium ions in the water sample;

[0017] Step 4: Determination of magnesium content in actual water samples: Collect the water sample to be tested, measure it into a colorimetric tube, and then add ammonium oxalate, triethanolamine, ascorbic acid, acid chrome blue K ethanol solution, NH 3 -NH 4 Cl buffer solution, diluted to the scale, and color development was performed. After color development for 5-10 minutes at room temperature, a mobile phone was used to take and store images in a 3D printed light-proof container with the light source turned on. The R value of the color development solution photo was read 3 times using a mobile phone application software, and the average value was taken for data processing. The data was then brought into the standard curve in the step to obtain the magnesium ion content in the water sample.

[0018] In a preferred implementation, the concentrations of the standard solutions of total calcium and magnesium ions in the steps are 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 mg / L, respectively.

[0019] In a preferred embodiment, the total amount of calcium and magnesium ion standard solution in step 1 or the water sample to be tested in step 3 is mixed with acid chrome blue K solution, NH 3 -NH 4 The volume ratio of Cl buffer solution added was 1:1:1.5.

[0020] In a preferred embodiment, the volumes of the magnesium ion standard solution in step 2 are 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mL, respectively.

[0021] In a preferred embodiment, in step 2 and step 4, ammonium oxalate, triethanolamine, ascorbic acid, acid chrome blue K ethanol solution, NH 3 -NH 4 The added volumes of Cl buffer solution were 0.8, 0.4, 0.8, 1.6, and 2 mL, respectively.

[0022] In a preferred implementation, the mobile phone application software is one of the three software F color pickers, Colorcoll, and Colormax in the IOS market or a software color picker in the Android market, preferably F color picker.

[0023] In a preferred embodiment, the NO 3 - 、SO 4 2- and Cl - The concentrations were all lower than 100 μg / L.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) when using the built-in App of a smart phone to extract and analyze the RGB channel signal value information of each channel, the present invention selects a fixed color picking point, thereby ensuring the accuracy of color picking and improving the accuracy of App image analysis. Moreover, during the determination process, the R channel shows a good fitting trend with the standard curve, and shows an upward trend as the concentration of the standard solution increases, while the G channel and the B channel are not linearly related to the concentration of the standard solution. Therefore, the R channel value is selected as the detection digital channel of the present method. Regardless of using different software or different brands and models of mobile phones, the R channel digital signal value still maintains a good linear correlation with the total amount of calcium and magnesium and the magnesium content, indicating that the present method has good general applicability. Moreover, when the water sample composition is complex, the influence of different interfering ions on the determination of calcium and magnesium concentrations is small.

[0025] (2) The color developer used in the present invention, acid chrome blue K in NH 3-NH 4 Under the alkaline conditions created by Cl buffer solution, acid chrome blue K is blue, and after combining with calcium and magnesium ions, it forms a red complex, so the solution appears purple-red, and ammonium oxalate is added to remove the interference of calcium ions to avoid affecting the measurement results;

[0026] (3) The method of the present invention can overcome the shortcomings of traditional detection methods to a certain extent. It uses the principle of light absorption by colored objects to establish a rapid quantitative multi-parameter index analysis method that can instantly measure the calcium and magnesium ion content in water on site. The method is simple, portable, accurate, precise, low-cost, and has strong anti-interference ability. It can be measured on site in situ, meeting the requirements of rapid in situ quantitative analysis of environmental water samples, and provides a new idea for the detection of calcium and magnesium content in water environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the F color picker operation interface diagram;

[0028] Figure 2 This is a real picture of a 3D printed light-proof container. Figure 2 (a) is the structural diagram; Figure 2 (b) is a photographic image;

[0029] Figure 3 The standard curve for determining the concentration of calcium and magnesium in water is the digital signal value of different channels, where Figure 3 (a) is the standard curve of the total amount of calcium and magnesium; Figure 3 (b) Standard curve of magnesium content;

[0030] Figure 4 The standard curves for determining calcium and magnesium concentrations in water using different software are shown below: Figure 4 (a) is the standard curve of the total amount of calcium and magnesium; Figure 4 (b) Standard curve of magnesium content;

[0031] Figure 5 The standard curve for measuring calcium and magnesium concentration in water by different mobile phones is as follows: Figure 5 (a) is the standard curve of the total amount of calcium and magnesium; Figure 5 (b) Standard curve of magnesium content;

[0032] Figure 6 is the linear correlation curve between UV spectrophotometer and smartphone graphic colorimetry; Figure 6 (a) is a curve diagram of the total amount of calcium and magnesium; Figure 6 (b) is a graph of the total amount of magnesium. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution, the present invention is described in detail below in conjunction with embodiments. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0034] In the following examples, the calcium ion standard solution, magnesium ion standard solution, NO 3 - Standard solution, SO 4 2- Standard solution, Cl - The standard solution was from the National Nonferrous Metals and Electronic Materials Analysis Co., Ltd., c = 1000 μg / mL, and ascorbic acid was from Shanghai MacLean Biochemical Technology Co., Ltd. pH = 10 NH 3 -NH 4 Cl buffer solution: Take 54 g NH 4 Dissolve Cl in water, add 350 mL of concentrated ammonia, and dilute to 1000 mL with water.

[0035] The use of the mobile phone application software F color picker in the following embodiment is: in a 3D printed black opaque container, a white light source is used to pass through different colored glasses and then illuminate the colorimetric dish through a diffuser plate, and a smart phone is used to take photos and samples. The RGB signal channel values ​​are extracted through analysis by the smart phone APP, and the data is recorded and a curve is established. After the color reaction, the solution is poured into the colorimetric dish and placed in the 3D printed opaque container, and the mobile phone is placed in the corresponding position. Click on the F color picker, click on the color picker to focus, fix the color picking point, and prevent errors caused by inconsistent points. After that, direct shooting analysis and sampling photo analysis are performed, and the RGB channel signal values ​​of the sample after extraction are displayed below. Click the record button in the lower right corner, and the recorded data will be stored in the color picking history, which is convenient for data recording in groups, such as Figure 1 The cuvettes containing the samples are placed on both sides of the 3D printed light-proof container. The cuvette holes are close to the middle baffle. The smartphone is fixed on one end of the outside of the 3D printed light-proof container. The camera is aimed at the six light channels. The center of each color point is close to the bottom of the cuvette. Multiple groups of R channel signal values ​​are read to obtain the accurate sample concentration, such as Figure 2 shown.

[0036] Embodiment 1:

[0037] A method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method comprises the following steps:

[0038] Step 1. Determination of the total calcium and magnesium standard curve: Mix equal volumes of 10 mg / L calcium ion standard solution and 10 mg / L magnesium ion standard solution, and then dilute them into total calcium and magnesium ion standard solutions with concentrations of 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 mg / L, respectively, and take 1 mL of each solution into a 10 mL colorimetric tube, and then add 1 mL of 5×10-4 mol / L acid chrome blue K solution, 1 mL of pH=10 NH 3 -NH 4 Cl buffer solution 1.5 mL was mixed to obtain a color solution, which was diluted to the scale for color development. After color development for 10 min at room temperature, a portion of the solution was poured out using a 3 mL cuvette, and an image was taken with a mobile phone in a 3D printed light-proof container with the light source turned on. The R value of the color solution photo was read 3 times using the iPhone 13 mobile phone F color picker application software, and the average value was taken. The data was processed to establish a relationship curve between the digital signal value of the R channel and different concentrations, and fitted into a standard curve;

[0039] Step 2, determination of magnesium content standard curve: dilute 1000 mg / L magnesium ion standard solution to 10 mg / L, then measure 0, 0.2, 0.4, 0.6, 0.8, 1.0 mL of magnesium ion standard solution, respectively, in 10 mL colorimetric tubes, and then add 0.1 mol / L ammonium oxalate 0.8 mL, 34% triethanolamine 0.4 mL, 5% ascorbic acid 0.8 mL, 0.02% acid chrome blue K ethanol solution 1.6 mL, pH = 10 NH 3 -NH 4 2 mL of Cl buffer solution was diluted to the scale for color development. After color development for 10 min at room temperature, part of the solution was poured out using a 3 mL cuvette. The image was taken and stored using a mobile phone in a 3D printed light-proof container with the light source turned on. The R value of the color development solution photo was read 3 times using the iPhone 13 F color picker application software, and the average value was taken. The data was processed to establish a relationship curve between the digital signal value of the R channel and different concentrations, and fitted into a standard curve;

[0040] Step 3: Determination of the total amount of calcium and magnesium in the actual water sample: Collect the water sample to be tested, measure 1 mL into a colorimetric tube, and then add 5×10 -4 1 mL of 1 mol / L acid chrome blue K solution, NH 3 -NH 4Cl buffer solution 1.5 mL was mixed to obtain a color solution, diluted to the scale, and a color reaction was performed. After color development at room temperature for 10 min, a portion of the solution was poured out using a 3 mL cuvette, and an image was taken with a mobile phone in a 3D printed light-proof container with the light source turned on. The R value of the color solution photo was read 3 times using the iPhone 13 mobile phone F color picker application software, and the average value was taken and data processing was performed. The data was then brought into the standard curve in the step to obtain the total amount of calcium and magnesium ions in the water sample.

[0041] Step 4, determination of magnesium content in actual water samples: collect the water sample to be tested, measure 1 mL into a 10 mL colorimetric tube, add 0.8 mL of 0.1 mol / L ammonium oxalate, 0.4 mL of 34% triethanolamine, 0.8 mL of 5% ascorbic acid, 1.6 mL of 0.02% acid chrome blue K ethanol solution, and 1.6 mL of pH=10 NH 3 -NH 4 2 mL of Cl buffer solution was diluted to the scale for color development. After color development for 10 min at room temperature, part of the solution was poured out using a 3 mL cuvette. The image was taken with a mobile phone in a 3D printed light-proof container with the light source turned on. The R value of the color development solution photo was read 3 times using the iPhone 13 F color picker application software, the average value was taken, and the data was processed. The data was then substituted into the standard curve in the step to obtain the magnesium ion content in the water sample.

[0042] The standard curves of the total amount of calcium and magnesium and the magnesium content measured at different channel digital signal values ​​in the above embodiment are as follows: Figure 3 As shown in the figure, whether it is the determination of the total calcium and magnesium standard curve or the determination of the magnesium content standard curve, the R channel shows a good fitting trend with the standard curve, and it increases with the increase of the concentration of the standard solution, while the G channel and the B channel are not linearly related to the concentration of the standard solution. The linear equation of the total calcium and magnesium standard curve is y=23.89x+172.31, and the linear correlation coefficient R 2 =0.9959; the linear equation of magnesium content is y=748.57x+155.91, and the highest linear correlation coefficient is R 2 =0.9965. Therefore, the R channel value is selected as the detection digital channel of this method.

[0043] Embodiment 2:

[0044] The difference between this embodiment and embodiment 1 is that different mobile phone software applications are used. In order to verify the applicability of the method, three softwares in the IOS market (F color picker, Colorcoll, Colormax) and one software (color picker) in the Android market are selected for comparison. After the total amount of calcium and magnesium and the magnesium solution are subjected to color development reaction respectively, the standard solutions with different total amounts of calcium and magnesium and different magnesium contents are photographed and saved in a 3D printed light-proof container using iPhone13, and the images are respectively picked up using four softwares. The color picking process of the Android software is to transfer the same picture taken by iPhone13 to the Redmi note12, and use the color picker to pick up the color of the image. The results are as follows Figure 4 As shown in the figure, it can be seen that the processing results of each software for the same set of pictures are roughly the same, so the influence of using different software on the method of the present invention can be ignored.

[0045] Embodiment 3:

[0046] In order to verify the universal applicability of this method, based on the same concentration gradient standard solution, experimental discussion and optimization were carried out on sample photos taken by the same smartphone and sample photos taken by different smartphones. In this example, iPhone 13, Redmi Note 12 and Huawei P30 were used to take pictures of the standard solution of total calcium and magnesium and the magnesium content, and a linear relationship diagram between the R channel and the solution concentration was drawn after color selection by the F color picker. The results are shown in the figure. Figure 5 As shown. The R channel digital signal values ​​for color processing vary from brand to brand, but they still maintain a good linear correlation with the total amount of calcium and magnesium and the magnesium content, which illustrates the applicability of this method. Comparing the measurement results of the three mobile phones, it can be seen that the iPhone 13 has the best linear correlation.

[0047] Embodiment 4:

[0048] In order to test the influence of different interfering ions on the determination of calcium and magnesium content by smartphone graphic colorimetry, this example selected three ions in water that may interfere with the determination of calcium and magnesium content: including NO 3 - 、SO 4 2- and Cl - As interfering ions, standard stock solutions were used to prepare solutions of different concentrations for determination, and the anti-interference ability of this method in the presence of the above anions was tested. The test results of calcium and magnesium recovery rates are shown in Table 1. The test results show that the recovery rate is good, and the influence of each ion on the determination of calcium and magnesium concentration is small. Therefore, the method of the present invention can be applied to NO 3 - 、SO 4 2- and Cl - Determine the calcium and magnesium content in water bodies with concentrations below 100μg / L.

[0049] Table 1 Recovery rate in the presence of interfering ions

[0050] Embodiment 5:

[0051] In this example, 10 mL of ultrapure water was taken and the experimental conditions were exactly the same as those in Example 1. The R-channel digital signal value was determined by digital image colorimetry. The determination was repeated 10 times, and the standard deviation (S) was calculated. The R-channel digital signal value was substituted into the above-mentioned standard curve equation for the total amount of calcium and magnesium and the standard curve equation for the magnesium content, respectively, to obtain the measured value, and the detection limit of the method was calculated. The detection limit of the total amount of calcium and magnesium in the method of the present invention was 0.27 mg / L and the detection range of the magnesium content was 0.08 mg / L.

[0052] 1. Feasibility verification of the method of the present invention

[0053] The standard curves of total calcium and magnesium and magnesium content measured by the smartphone graphic colorimetry method were compared with the results of the spectrophotometer method to verify the accuracy of the method. In order to prevent other factors from interfering with the measurement results, the measurement steps of the spectrophotometer method are basically the same as those of the graphic colorimetry method. Figure 6 It can be seen that the measured results are basically consistent with the samples of the same concentration measured by UV split-tube photometry, which shows that this method is feasible.

[0054] 2. Verification of the practicality and accuracy of the method of the present invention

[0055] In order to test the practicality and accuracy of the method, the graphic colorimetry of the above embodiment 1 was used to analyze the calcium and magnesium ion content in three actual water samples (tap water, river water, and lake water) on site. The three water samples were collected and measured on the same day. They were collected from 508 North of the Eighth Teaching Building of Hunan Agricultural University, the lake near Yiyuan Road of Hunan Agricultural University, and the Liuyang River in the Binhe Road section. Each sample was measured 3 times and the average value was taken. The results are shown in Table 2. The collected river water samples were diluted 5 times for color development reaction and then the total amount of calcium and magnesium was measured by digital image colorimetry. The recovery rate of magnesium content was measured by digital image colorimetry after diluting 10 times for color development reaction. Each sample was measured three times under the same experimental conditions. The results are distributed as shown in Tables 3 and 4. For real water samples, digital image colorimetry can still be used, which provides feasibility for on-site analysis.

[0056] Table 2 Determination of calcium and magnesium content in actual water samples by smartphone graphic colorimetry

[0057] Table 3 Recovery of total calcium and magnesium in actual water samples determined by smartphone graphic colorimetry

[0058] Table 4 Recovery rate of magnesium content in actual water samples determined by smartphone graphic colorimetry

[0059] It should be noted that, in this article, the terms: include, contain and any other variants are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Specific examples are used in this article to illustrate the principle and implementation of the technical solution of the present invention. The above examples are only used to help understand the method of the present invention and its core idea. The above is only a preferred implementation of the present invention. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements, modifications or changes can be made, and the above technical features can also be combined in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the present invention to other occasions without improvement, should be regarded as the protection scope of the present invention.

Claims

1. A method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method, characterized in that: The following steps are involved: Step 1, determination of the total amount of calcium and magnesium standard curve: the calcium ion standard solution and the magnesium ion standard solution were mixed in equal volumes, and then diluted into different concentrations of calcium and magnesium ion total amount standard solutions, respectively measured in colorimetric tubes, and then acid chrome blue K solution and NH3-NH4Cl buffer solution were added to mix to obtain a color solution, diluted to the scale, and a color reaction was performed. After color development for 5-10 minutes at room temperature, the image was taken and stored with a mobile phone in a 3D printed light-proof container with the light source turned on, and the R value of the color solution photo was read 3 times using a mobile phone application software, and the average value was taken, and data processing was performed to establish a relationship curve between the R channel digital signal value and different concentrations, and fit to a standard curve; Step 2, determination of magnesium content standard curve: dilute the magnesium ion standard solution, then measure different volumes of magnesium ion standard solution, respectively, in colorimetric tubes, and then add ammonium oxalate, triethanolamine, ascorbic acid, acid chrome blue K ethanol solution, NH3-NH4Cl buffer solution, respectively, dilute to scale, and perform color development reaction. After color development for 5-10 minutes at room temperature, use a mobile phone to take and store images in a 3D printed light-proof container with the light source turned on, use a mobile phone application software to read the R value of the color development solution photo 3 times, take the average value, and perform data processing to establish a relationship curve between the R channel digital signal value and different concentrations, and fit it into a standard curve; Step 3, determination of the total amount of calcium and magnesium in the actual water sample: collect the water sample to be tested, measure it into a colorimetric tube, add acid chrome blue K solution and NH3-NH4Cl buffer solution to mix to obtain a colorimetric solution, dilute to the scale, and perform a colorimetric reaction. After color development for 5-10 minutes at room temperature, use a mobile phone to take a photo of the colorimetric solution in a 3D printed light-proof container with the light source turned on, use a mobile phone application software to read the R value of the colorimetric solution photo 3 times, take the average value, and perform data processing, and then bring the data into the standard curve in step (1) to obtain the total amount of calcium and magnesium ions in the water sample; Step 4, determination of actual magnesium content in water sample: collect the water sample to be tested, measure it into a colorimetric tube, then add ammonium oxalate, triethanolamine, ascorbic acid, acid chrome blue K ethanol solution, and NH3-NH4Cl buffer solution, dilute to the scale, and perform color development reaction. After color development for 5-10 minutes at room temperature, use a mobile phone to take and store the image in a 3D printed light-proof container with the light source turned on, use the mobile phone application software to read the R value of the color development solution photo 3 times, take the average value, and perform data processing, and then bring the data into the standard curve in step (2) to obtain the magnesium ion content in the water sample.

2. The method for determining calcium and magnesium in environmental water by a smartphone graphic colorimetric method according to claim 1, characterized in that: The concentrations of the total amount of calcium and magnesium ion standard solutions in step (1) are 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 mg / L, respectively.

3. The method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method according to claim 1, characterized in that: The volume ratio of the total amount of calcium and magnesium ion standard solution in step 1 or the water sample to be tested in step 3 to the acid chrome blue K solution and the NH3-NH4Cl buffer solution is 1:1:1.

5.

4. The method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method according to claim 1, characterized in that: The measured volumes of the magnesium ion standard solution in step 2 are 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mL, respectively.

5. The method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method according to claim 1, characterized in that: In the step 2 and step 4, the added volumes of ammonium oxalate, triethanolamine, ascorbic acid, acid chrome blue K ethanol solution, and NH3-NH4Cl buffer solution are 0.8, 0.4, 0.8, 1.6, and 2 mL, respectively.

6. The method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method according to claim 1, characterized in that: The mobile phone application software is one of the three software F color pickers, Colorcoll, and Colormax in the IOS market or a software color picker in the Android market.

7. The method for determining calcium and magnesium in environmental water using a smartphone graphic colorimetric method according to claim 6, characterized in that: The mobile phone application software selects F color picker.

8. The method for determining calcium and magnesium in environmental water using a smart phone graphic colorimetry method according to claim 1, characterized in that: The NO content of the water sample to be tested 3- 、SO4 2- and Cl - The concentrations were all lower than 100 μg / L.

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