Detection method of perchlorate

Abstract

The invention relates to the field of detection, in particular to a perchlorate detection method which is characterized by comprising the following steps: (1) enabling a water sample to pass through a filter membrane to obtain a to-be-detected sample, and storing the to-be-detected sample in a closed container; the volume ratio of the sample to be detected to the air in the closed container is (1-2): 1; (2) the sample to be detected and a color developing agent are subjected to a color developing reaction, and an organic layer containing perchlorate is obtained after liquid-liquid extraction; and (3) shooting the organic layer, then extracting an RGB signal channel value of a picture obtained by shooting, and analyzing and calculating the content of perchlorate in the sample to be detected. The detection method has good accuracy and stability on the determination of the perchlorate.

Description

Technical Field

[0001] The present invention relates to the field of detection, and particularly to a method for detecting perchlorate. Background Art

[0002] Perchlorate (ClO4) is a new type of pollutant, which is widely used in industrial fields such as aviation equipment, fireworks, etc. During production and use, it may be released into surface water and the atmosphere, causing diseases. Perchlorate has low adsorption in water and strong solubility, which is likely to cause pollution of environmental water bodies and even domestic drinking water. After oral ingestion, perchlorate will cause hypothyroidism in the human body, disrupt the body's metabolism, and affect the growth and development of the human body. To protect human health and provide safety guarantee for drinking water, the standard method for detecting perchlorate concentration must be accelerated. Therefore, it is particularly important to establish a rapid, accurate, economical, and sensitive detection method for perchlorate in water to protect the safety of water environment.

[0003] Currently, the detection methods for perchlorate mainly include ion chromatography, ion chromatography-mass spectrometry, liquid chromatography-mass spectrometry, gravimetry, spectrophotometry, ion selective electrode method, atomic absorption spectrometry, etc. However, these methods each have certain defects, such as poor accuracy and reproducibility.

[0004] Therefore, there is an urgent need to provide a detection method for perchlorate, which has good accuracy and stability for the determination of perchlorate. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of low accuracy and stability of the existing detection methods for perchlorate, and provide a detection method for perchlorate, which has good accuracy and stability for the determination of perchlorate.

[0006] To achieve the above purpose, the present invention provides a detection method for perchlorate, including the following steps:

[0007] (1) After filtering the water sample through a filter membrane, the sample to be tested is obtained, and the sample to be tested is stored in a sealed container;

[0008] (2) The sample to be tested and the color reagent are subjected to a color reaction, and after liquid-liquid extraction, an organic layer containing perchlorate is obtained;

[0009] (3) Photograph the organic layer, then extract the RGB signal channel values of the photographed image, and analyze and calculate the content of perchlorate in the sample to be measured; when the concentration of perchlorate in the standard concentration is greater than 0 μg / L and less than or equal to 100 μg / L, with the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, establish a standard curve of the concentration of perchlorate and the R value in the perchlorate aqueous solution. The linear equation of the standard curve is y = ax + b, and the linear correlation coefficient > 0.99. Substitute the R value of the sample to be measured into the standard curve to calculate the content of perchlorate in the sample to be measured; when the concentration of perchlorate in the standard concentration is greater than 100 μg / L and less than or equal to 3000 μg / L, with the logarithm of 10 times the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, establish a standard curve of the logarithm of 10 times the concentration of perchlorate and the R value in the perchlorate aqueous solution. The quadratic fitting equation of the standard curve is y = Ax 2 + Bx + C, and the correlation coefficient > 0.99. Substitute the R value of the sample to be measured into the standard curve to calculate the content of perchlorate in the sample to be measured.

[0010] Preferably, when the concentration of perchlorate in the standard concentration is greater than 0 μg / L and less than or equal to 100 μg / L, a in the linear equation is -700 to -500, and b is 100 - 300.

[0011] Preferably, when the concentration of perchlorate in the standard concentration is greater than 100 μg / L and less than or equal to 3000 μg / L, A in the linear equation is -10 to -5, B is -15 to -10, and C is 100 - 300.

[0012] Preferably, in step (1), the volume ratio of the sample to be measured to air in the sealed container is 1 - 2:1.

[0013] Preferably, in step (1), the storage conditions include at least: 0 - 4 °C.

[0014] Preferably, in step (1), the pore size of the filter membrane is 0.4 - 0.5 μm.

[0015] Preferably, the water sample is selected from at least one of well water, tap water, river water, rural ditch water, and industrial wastewater.

[0016] Preferably, in step (2), the color reagent is selected from at least one of methylene blue, malachite green, crystal violet, and rhodamine B, and preferably methylene blue.

[0017] Preferably, the developer is an aqueous solution of the developer, and the concentration of the developer in the aqueous solution of the developer is 5×10 -4 -10 -2 mol / L, and more preferably 0.9 - 1.1×10 -4 mol / L.

[0018] Preferably, the volume ratio of the sample to be measured to the developer is 1:9 - 10.

[0019] Preferably, before the color reaction, a buffer solution is added to the sample to be measured.

[0020] Preferably, the buffer solution is selected from CH3COOH - CH3COONa buffer solution and / or PBS buffer solution, and more preferably CH3COOH - CH3COONa buffer solution.

[0021] Preferably, the pH of the buffer solution is 4 - 7.5, and more preferably 4 - 5.

[0022] Preferably, the volume ratio of the buffer solution to the sample to be measured is 1:0.5 - 0.6.

[0023] Preferably, in step (2), the process of liquid - liquid extraction includes: mixing the reaction solution obtained from the color reaction, a dispersant, and an extractant, and then separating them.

[0024] Preferably, the dispersant is methanol and / or ethanol, and more preferably methanol; the extractant is selected from at least one of dichloromethane, ethyl acetate, toluene, and chloroform, and more preferably dichloromethane.

[0025] Preferably, the separation is centrifugal separation.

[0026] Preferably, the conditions for the separation include at least: the rotation speed is 4000 - 5000 rpm, and the time is 4 - 8 min.

[0027] Preferably, in step (3), the photographing is carried out in a light - proof device, and the organic layer is irradiated with a light source.

[0028] Preferably, the light source is white light.

[0029] Preferably, in step (3), the RGB signal channel value selects the R value.

[0030] By the above technical solutions, the beneficial effects of the present invention are as follows: The detection method provided by the present invention for determining perchlorate has good accuracy and stability. Compared with the results measured by ion chromatography and liquid chromatography - mass spectrometry, the results are close, and the error is less than 5%. Moreover, this detection method is simple and has good stability.

[0031] Other features and advantages of the present invention will be described in detail in the following specific implementation part. Description of the Drawings

[0032] Figure 1 It is the detection flow chart of perchlorate in the present invention;

[0033] Figure 2 It is the structural schematic diagram of the light-shielding device in the present invention;

[0034] Figure 3 It is the relationship curve graph of the R value and the perchlorate standard solution in Example 1. The concentration of perchlorate in I is greater than 0 μg / L and less than or equal to 100 μg / L, and the concentration of perchlorate in II is greater than 100 μg / L and less than or equal to 3000 μg / L;

[0035] Figure 4 It is the relationship curve and correlation coefficient graph of the R value, G value, and B value and the perchlorate standard solution established in Example 3, Example 8, and Example 9;

[0036] Figure 5 It is the relationship curve and correlation coefficient graph of the R value, G value, and B value and the perchlorate standard solution established in Example 4, Example 10, and Example 11;

[0037] Figure 6 It is the relationship curve and correlation coefficient graph of the R value, G value, and B value and the perchlorate standard solution established in Example 5, Example 12, and Example 13;

[0038] Figure 7 It is the relationship curve and correlation coefficient graph of the R value, G value, and B value and the perchlorate standard solution established in Example 1, Example 6, and Example 7;

[0039] Figure 8 It is the standard curve and correlation coefficient graph of the R value and perchlorate (0 - 0.1 mg / L) in Example 1, Example 14 - Example 16;

[0040] Figure 9 It is the standard curve and correlation coefficient graph of the R value and perchlorate (0.1 - 0.8 mg / L) in Example 1, Example 14 - Example 16;

[0041] Figure 10 It is the standard curve and correlation coefficient graph of the R value and perchlorate in Example 1, Example 17 - Example 20;

[0042] Figure 11 It is the correlation coefficient graph corresponding to the standard curve of the R value and perchlorate in Example 1, Example 21 - Example 22.

[0043] Reference Signs

[0044] 1 - Box body; 11 - Inner box body; 12 - Outer box body; 2 - Light filtering structure; 3 - Image processing structure; 4 - Light source; 5 - Shooting structure; 6 - Power supply; 7 - Sample. Detailed Embodiment

[0045] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0046] The present invention provides a method for detecting perchlorate, comprising the following steps:

[0047] (1) After passing the water sample through a filter membrane, a sample to be measured is obtained, and the sample to be measured is stored in a sealed container;

[0048] (2) Performing a color reaction on the sample to be measured and a color developing agent, and obtaining an organic layer containing perchlorate after liquid - liquid extraction;

[0049] (3) Photographing the organic layer, then extracting the RGB signal channel values of the photographed picture, and analyzing and calculating the content of perchlorate in the sample to be measured; when the concentration of perchlorate in the standard concentration is greater than 0 μg / L and less than or equal to 100 μg / L, taking the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, establishing a standard curve of the concentration of perchlorate and the R value in the perchlorate aqueous solution, the linear equation of the standard curve is y = ax + b, and the linear correlation coefficient > 0.99, substituting the R value of the sample to be measured into the standard curve to calculate the content of perchlorate in the sample to be measured; when the concentration of perchlorate in the standard concentration is greater than 100 μg / L and less than or equal to 3000 μg / L, taking the logarithm of 10 times the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, establishing a standard curve of the logarithm of 10 times the concentration of perchlorate and the R value in the perchlorate aqueous solution, the quadratic fitting equation of the standard curve is y = Ax 2 Bx + C, and the correlation coefficient > 0.99, substituting the R value of the sample to be measured into the standard curve to calculate the content of perchlorate in the sample to be measured.

[0050] During the research process, the inventors of the present invention unexpectedly found that this detection method has good accuracy and stability for determining perchlorate. Compared with the results measured by ion chromatography and liquid chromatography-mass spectrometry, the results are close, with an error of less than 5%. Moreover, this detection method is simple and has good stability.

[0051] According to the present invention, for the detection process of perchlorate, refer to Figure 1 , Figure 1 where reagent A is a dispersant and reagent B is an extractant.

[0052] According to the present invention, in step (3), when the concentration of perchlorate in the standard concentration is greater than 100 μg / L and less than or equal to 3000 μg / L, the logarithm of 10 times the concentration of perchlorate in the aqueous solution of perchlorate with the standard concentration is used as the abscissa x, which means the abscissa x is ln[10*C(ClO4 - )].

[0053] According to the present invention, in order to further improve the accuracy of perchlorate detection, preferably, when the concentration of perchlorate in the standard concentration is greater than 0 μg / L and less than or equal to 100 μg / L, a in the linear equation is -700 to -500, specifically it can be -700, -600, -500, or any value between the aforementioned two values; b is 100 - 300, specifically it can be 100, 200, 300, or any value between the aforementioned two values.

[0054] According to the present invention, in order to further improve the accuracy of perchlorate detection, preferably, when the concentration of perchlorate in the standard concentration is greater than 100 μg / L and less than or equal to 3000 μg / L, A in the linear equation is -10 to -5, specifically it can be -10, -8, -5, or any value between the aforementioned two values; B is -15 to -10, specifically it can be -15, -12, -10, or any value between the aforementioned two values; C is 100 - 300, specifically it can be 100, 200, 300, or any value between the aforementioned two values.

[0055] According to the present invention, in step (1), the volume ratio of the sample to be tested to air in the closed container is 1 - 2:1, specifically it can be 1:1, 1:1.5, 1:2, or any value between the aforementioned two values. The inventors found that under this preferred embodiment, the stability of perchlorate in the sample to be tested during storage can be improved, thereby improving the accuracy of perchlorate detection.

[0056] According to the present invention, in order to further improve the stability of perchlorate and the accuracy of detection, preferably, in step (1), the storage conditions at least include: 0 - 4 °C, specifically it can be 0 °C, 2 °C, 4 °C, or any value between the aforementioned two values.

[0057] According to the present invention, preferably, in step (1), the pore size of the filter membrane is 0.4 - 0.5 μm, specifically, it can be 0.4 μm, 0.45 μm, 0.5 μm, or any value between the aforementioned two values. The inventors have found that under this preferred embodiment, impurities and microorganisms in the water sample can be removed, the influence of impurities and microorganisms on the detection can be reduced, and thus the accuracy of the detection can be improved.

[0058] According to the present invention, the water sample can be a water sample from any source in the natural environment, and the tester can select it according to needs. Preferably, the water sample is selected from at least one of well water, tap water, river water, rural ditch water, and industrial wastewater.

[0059] According to the present invention, the color reagent can be a conventional selection in the art. Preferably, in step (2), the color reagent is selected from at least one of methylene blue, malachite green, crystal violet, and rhodamine B, and preferably methylene blue. The inventors have found that under this preferred embodiment, the complexation effect of the color reagent and perchlorate can be significantly improved, and thus the accuracy of the detection can be improved.

[0060] According to the present invention, perchlorate in the sample to be tested can form a complex with the color reagent. Exemplarily, when the color reagent is methylene blue, the methylene blue solution and ClO4 in water - complex at a ratio of n:n = 1:1 to form a blue complex. Under the action of the extractant, the complex is extracted into the organic phase and sinks to the bottom of the solution. The higher the concentration of ClO4 in the medium - , the deeper the color. The reaction formula is as follows:

[0061] C 16 H 18 N3SCl + +ClO4 - →C 16 H 18 N 3S Cl·ClO4.

[0062] According to the present invention, in order to further improve the complexation effect of the color reagent and perchlorate, and thus improve the accuracy of the detection, preferably, the color reagent is an aqueous solution of the color reagent, and the concentration of the color reagent in the aqueous solution of the color reagent is 5×10 -4 -10 -2 mol / L, specifically, it can be 5×10 -4 mol / L, 10 -3 mol / L, 5×10 -3 mol / L, 10 -2 mol / L, or any value between the aforementioned two values. Further preferably, it is 0.9 - 1.1×10 -4mol / L.

[0063] According to the present invention, in order to further improve the complexation effect between the color reagent and perchlorate, and thus improve the accuracy of detection, preferably, the volume ratio of the sample to be tested and the color reagent is 1:9 - 10, specifically 1:9, 1:9.5, 1:10, or any value between the aforementioned two values.

[0064] According to the present invention, preferably, before the color reaction, a buffer solution is added to the sample to be tested. The inventor found that in this preferred embodiment, the complexation effect between perchlorate and the color reagent can be further improved, and thus the accuracy of detection can be further improved.

[0065] According to the present invention, in order to further improve the complexation effect between perchlorate and the color reagent, preferably, the buffer solution is selected from CH3COOH - CH3COONa buffer solution and / or PBS buffer solution, and more preferably CH3COOH - CH3COONa buffer solution.

[0066] According to the present invention, in order to further improve the complexation effect between perchlorate and the color reagent, preferably, the pH of the buffer solution is 4 - 7.5, specifically 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, or any value between the aforementioned two values, and more preferably 4 - 5.

[0067] According to the present invention, in order to further improve the complexation effect between perchlorate and the color reagent, preferably, the volume ratio of the buffer solution to the sample to be tested is 1:0.5 - 0.6, specifically 1:0.5, 1:0.55, 1:0.6, or any value between the aforementioned two values.

[0068] According to the present invention, liquid - liquid extraction can be a conventionally selected liquid - liquid extraction method in the art. Preferably, in step (2), the process of liquid - liquid extraction includes: mixing the reaction solution obtained from the color reaction, a dispersant, and an extractant and then separating them. The inventor found that in this preferred embodiment, the complex of perchlorate and the color reagent is extracted into the organic phase through the process of liquid - liquid extraction, which is convenient for subsequent photographing, can improve the accuracy of the RGB signal channel values of the obtained pictures, and thus improve the accuracy of detection.

[0069] According to the present invention, the dispersant can be any organic solvent, such as methanol, ethanol, ethyl acetate, acetone, etc. In order to further improve the dispersion effect, preferably, the dispersant is methanol and / or ethanol, and more preferably methanol. In order to further improve the effect of liquid - liquid extraction, preferably, the extractant is selected from at least one of dichloromethane, ethyl acetate, toluene, and chloroform, and more preferably dichloromethane.

[0070] According to the present invention, the separation can be carried out by a separation method conventionally selected in the art, such as filtration, suction filtration, centrifugation, etc. To further improve the separation effect of the organic phase, preferably, the separation is centrifugal separation.

[0071] According to the present invention, to further improve the separation effect of the organic phase, preferably, the conditions of the separation at least include: the rotation speed is 4000 - 5000 rpm, specifically it can be 4000 rpm, 4200 rpm, 4400 rpm, 4600 rpm, 4800 rpm, 5000 rpm, or any value between the aforementioned two values; the time is 4 - 8 min, specifically it can be 4 min, 6 min, 8 min, or any value between the aforementioned two values.

[0072] According to the present invention, preferably, in step (3), the photographing is carried out in a light-shielding device, and a fill light is used to irradiate the organic layer. The inventor found that in this preferred embodiment, it is possible to avoid the influence of ambient light on the organic layer and thus affect the photographing effect, and further improve the accuracy of the RGB signal channel values of the extracted and photographed pictures.

[0073] In the present invention, referring to Figure 2 , the light-shielding device includes a box body 1 with one end open. Along the length direction of the box body 1, a light source 4, a light filtering structure 2, and an image processing structure 3 are sequentially arranged inside the box body 1. A photographing structure 5 is arranged at the open end of the box body 1. The image processing structure 3 is connected to the photographing structure 5. The light filtering structure 2 can perform light filtering processing of multiple colors on the light emitted by the light source 4. The light filtering structure 2 can be a colorimetric card, which can reduce color errors caused by different image processing structures 3, improve the accuracy of the results and the convenience of operation. A sample placement structure is also arranged inside the box body 1. The sample placement structure is located between the light source 4 and the photographing structure 5. When multiple samples 7 are placed in the sample placement structure, the light emitted by the light source 4 is filtered by the light filtering structure 2 to form light of multiple colors and irradiate the samples, and then the image processing structure 3 photographs and samples the colors of the samples after absorbing the corresponding color light from the photographing structure 5, so as to analyze and process the content of the target substance in the multiple samples 7, improving the convenience and detection efficiency of the light-shielding device.

[0074] In the present invention, the box body 1 includes an inner box body 11 and an outer box body 12. One end of the inner box body 11 along its length direction is open at the top. Grooves for facilitating the insertion of the sample 7 are provided on the opposite sides of the inner box body 11. One end of the outer box body 12 along its length direction is open at the bottom. Openings are provided on the opposite sides of the outer box body 12. The inner box body 11 and the outer box body 12 are snap-connected, which can shield the sample 7 from light and facilitate the focusing of mobile phone cameras of different models. A power supply 6 connected to the light source 4 is also provided inside the box body 1, so that the light-shielding device can be powered by the power supply 6 during mobile use, greatly improving the flexibility and convenience of the light-shielding device.

[0075] According to the present invention, the image processing structure 3 is a device in the prior art that can capture a color image and convert it into color values. It can be a smart phone and the image processing software in the phone or a camera and the image processing software in the computer connected thereto. For example, the phone can be iPhone 13, Honor Magic 4, Xiaomi 12, Redmi K50, etc., and the software can be Colormax, Colorcoll, F color picker, etc.

[0076] According to the present invention, the light source can be a light source in the prior art that can emit uniform white light. For example, it can be an LED white light lamp.

[0077] Exemplarily, for the light-shielding device, see Figure 2 , and the operation process includes: after the white light source 4 in the light-shielding device passes through the light filtering structure 4, irradiate the color comparison cell containing the sample 7, take a photo sample with the image processing structure 3, analyze and extract the RGB signal channel values through the image processing structure 3, record the data and establish a curve; after the color reaction, pour the solution into the color comparison cell and place it in the light-shielding device, and place the image processing structure 3 at the corresponding position; click on the F color picker, click to focus the color picker, fix the color picking point to prevent errors caused by inconsistent positions; then perform direct shooting analysis and sampled photo analysis, and display the RGB channel signal values of the sample 7 after extraction; click the record button, and the recorded data is stored in the color picking history for facilitating data recording in groups; place the color comparison cell containing the sample 7 on both sides of the light-shielding device, the color comparison cell holes are closely attached to the middle baffle, the image processing structure 3 is fixed at one end outside the light-shielding container, the camera is aligned with the six light channels, and the center of each color picking point is close to the bottom of the color comparison cell to read multiple groups of G channel signal values, and then obtain the accurate sample concentration.

[0078] According to the present invention, the RGB signal channel value can be the R value, G value or B value. Preferably, in step (3), the RGB signal channel value is the R value. The inventor found that in this preferred embodiment, by fitting a curve with the R value and the concentration of perchlorate, the detection effect and detection accuracy can be further improved.

[0079] As a particularly preferred embodiment of the present invention, a method for detecting perchlorate is provided, comprising the following steps:

[0080] (1) After passing the water sample through a filter membrane with a pore size of 0.4 - 0.5 μm, the sample to be tested is obtained, and the sample to be tested is placed in a sealed container and stored at a temperature of 0 - 4 °C; the volume ratio of the sample to be tested to air in the sealed container is 1 - 2:1;

[0081] (2) The sample to be tested and the chromogenic reagent aqueous solution with a volume ratio of 1:9 - 10 (the concentration of the chromogenic reagent in the chromogenic reagent aqueous solution is 0.9 - 1.1×10 -4 mol / L) are subjected to a chromogenic reaction. After mixing the reaction solution, dispersant, and extractant obtained from the chromogenic reaction, centrifugal separation is performed at a rotation speed of 4000 - 5000 rpm for 4 - 8 min to obtain an organic layer containing perchlorate;

[0082] (3) The organic layer is placed in a light-shielding device, irradiated with a white light supplementary lamp, photographed, and then the RGB signal channel values of the photographed image are extracted, and the R value is selected for the RGB signal channel value;

[0083] When the concentration of the perchlorate in the standard concentration is greater than 0 μg / L and less than or equal to 100 μg / L, with the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, a standard curve of the concentration and R value of perchlorate in the perchlorate aqueous solution is established. The linear equation of the standard curve is y = ax + b, and the linear correlation coefficient > 0.99. Among them, a is -700 to -500, and b is 100 - 300. Substitute the R value of the sample to be tested into the standard curve to calculate the content of perchlorate in the sample to be tested; when the concentration of the perchlorate in the standard concentration is greater than 100 μg / L and less than or equal to 3000 μg / L, with the logarithm of 10 times the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, a standard curve of the logarithm of 10 times the concentration of perchlorate in the perchlorate aqueous solution and the R value is established. The quadratic fitting equation of the standard curve is y = Ax 2 Bx + C6, and the correlation coefficient > 0.99. Substitute the R value of the sample to be tested into the standard curve to calculate the content of perchlorate in the sample to be tested;

[0084] Among them, in step (2), before the chromogenic reaction, a CH3COOH - CH3COONa buffer solution with a pH of 4 - 5 is added to the sample to be tested, and the volume ratio of the buffer solution to the sample to be tested is 1:0.5 - 0.6; the water sample is selected from at least one of well water, tap water, river water, rural ditch water, and industrial wastewater. The chromogenic reagent is methylene blue; the dispersant is methanol, and the extractant is dichloromethane.

[0085] In the above particularly preferred embodiment, the detection method for determining perchlorate has good accuracy and stability. Compared with the results obtained by ion chromatography and liquid chromatography-mass spectrometry, the results are close, with an error of less than 5%, and the detection method has good stability.

[0086] The present invention will be described in detail below through examples.

[0087] Unless otherwise specified in the following examples, the specific experimental conditions are usually in accordance with conventional conditions or the conditions recommended by reagent companies; for the reagents, consumables, etc. used in the following examples, unless otherwise specified, they can all be obtained through commercial channels, the experimental water is pure water, and the methods used, unless otherwise specified, are all conventional process methods in the art.

[0088] In the following examples, the preparation method of 10 -3 mol / L methylene blue solution is as follows: Weigh 0.3198 g of methylene blue and dilute it with water to 1000 mL. The preparation method of 10 -4 mol / L methylene blue solution is as follows: Take 10 mL of 10 -3 mol / L methylene blue solution and dilute it with water to 100 mL. The preparation method of pH = 4.5 CH3COOH-CH3COONa buffer solution is as follows: Dissolve 1.8 g of CH3COONa in water, then add 1 mL of glacial acetic acid and dilute it with water to 100 mL. The preparation method of ClO4 - standard stock solution is as follows: Take 1 mL of 1000 μg / mL ClO4 - standard solution and dilute it with water to 100 mL to prepare a standard stock solution with a concentration of 10 mg / L. The preparation method of ClO4 - standard intermediate solution is as follows: Take 10 mL of 10 mg / L standard stock solution and dilute it with water to 100 mL to prepare a standard intermediate solution with a concentration of 1 mg / L.

[0089] ClO4 - standard solution, Mg 2+ standard solution, NO3 - ion standard solution, SO4 2- ion standard solution, Cl - standard solution, K + standard solution are all purchased from the National Nonferrous Metals and Electronic Materials Analysis Co., Ltd. The light-shielding device is shown in Figure 2 .

[0090] Example 1

[0091] (1) Filter the impurities and microorganisms from the river water sample through a 0.45 μm filter membrane, collect it in a clean container, and store it in a 4 °C refrigerator to obtain the sample to be tested;

[0092] (2) Prepare standard solutions of perchlorate with concentrations of 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.4, 0.6, 0.7, 0.8, 1.0, 1.2, 1.5, 2.0, 2.5, 3.0 mg / L.

[0093] (3) Add 5 mL of the standard solution to a 15 mL centrifuge tube. Add 1 mL of CH3COOH-CH3COONa buffer solution with a pH of 4.5, 0.55 mL of 10 -4 mol / L methylene blue solution to each standard solution, make up to 10 mL with ultrapure water, add 70 μL of methanol as a dispersant, and 1 mL of dichloromethane as an extractant. Shake vigorously for 30 s, then centrifuge at 4000 rmp for 5 min. Inject the lower extraction phase taken out with a micro sampler into a 350 μL cuvette.

[0094] (4) Place the cuvette in a 3D printed light-shielding device with the light source on, use a white light fill light for supplementary lighting, use an iPhone 13 mobile phone to take samples of the extraction phase in the cuvette. Extract the R value, G value, and B value 3 times each through the F color picker APP, take the average value, and establish a relationship curve with the concentration respectively. It is found that by changing the concentration of perchlorate, the value of the R channel shows the largest change, showing a good fitting trend with the standard curve, as Figure 3 shown; while the G channel and B channel do not show a linear relationship with the standard solution concentration; from Figure 3 it can be seen that the three indicators fit the standard curve. Among them, Figure 3 for the standard curve obtained when the concentration of perchlorate is greater than 0 μg / L and less than or equal to 100 μg / L, with the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, the linear equation is y = -586.19x + 194.09, and the correlation coefficient R 2 = 0.9985; for the standard curve when the concentration of perchlorate is greater than 100 μg / L and less than or equal to 3000 μg / L, with the logarithm of 10 times the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, establish the standard curve of the logarithm of 10 times the concentration of perchlorate in the perchlorate aqueous solution and the R value. The quadratic fitting equation is y = -8.4695x 2 - 11.182x + 188.16, and the correlation coefficient R 2 = 0.9972;

[0095] (5) Extract the R value, G value, and B value of the test sample 3 times according to the methods in steps (3) and (4), and take the average value; calculate twice the corresponding concentration according to the drawn standard curve, which is the perchlorate content in the water sample.

[0096] Example 2

[0097] (1) Filter the impurities and microorganisms in the tap water sample through a 0.45 μm filter membrane, collect it in a clean container, and store it in a 0 °C refrigerator to obtain the test sample;

[0098] (2) Prepare a standard solution of perchlorate, and the concentrations of the perchlorate standard solution are 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.4, 0.6, 0.7, 0.8, 1.0, 1.2, 1.5, 2.0, 2.5, 3.0 mg / L.

[0099] (3) Add 5 mL of the standard solution to a 15 mL centrifuge tube. Add 1 mL of CH3COOH-CH3COONa buffer solution with a pH of 5, 0.5 mL of 10 -4 mol / L methylene blue solution to each standard solution, dilute to 10 mL with ultrapure water, add 70 μL of methanol as a dispersant, 1 mL of dichloromethane as an extractant, shake vigorously for 30 s, then centrifuge at 4000 rmp for 5 min, and inject the lower-layer extraction phase taken out with a micro-sampler into a 350 μL cuvette.

[0100] (4) Place the cuvette in a 3D printed light-shielding device with the light source turned on, use a white light fill light for supplementary lighting, use an iPhone 13 mobile phone to take pictures of the extraction phase in the cuvette for sampling, extract the R value obtained from the shooting 3 times through the F color picker APP, take the average value, and establish a relationship curve with the concentration;

[0101] (5) Extract the R value, G value, and B value of the test sample 3 times according to the methods in steps (3) and (4), and take the average value; calculate twice the corresponding concentration according to the drawn standard curve, which is the perchlorate content in the water sample.

[0102] Example 3

[0103] Detect the perchlorate content according to the detection method in Example 1, except that the color reagent is replaced by malachite green.

[0104] The relationship curve and correlation coefficient diagram established by the R value, G value, B value and the perchlorate standard solution are shown in Figure 4 .

[0105] Example 4

[0106] The perchlorate content was detected according to the detection method of Example 1, except that the color reagent was replaced with crystal violet.

[0107] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 5 。

[0108] Example 5

[0109] The perchlorate content was detected according to the detection method of Example 1, except that the color reagent was replaced with rhodamine B.

[0110] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 6 。

[0111] Example 6

[0112] The perchlorate content was detected according to the detection method of Example 1, except that the white light complementary color was replaced with the green complementary color.

[0113] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 7 。

[0114] Example 7

[0115] The perchlorate content was detected according to the detection method of Example 1, except that the white light complementary color was replaced with the warm yellow complementary color.

[0116] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 7 。

[0117] Example 8

[0118] The perchlorate content was detected according to the detection method of Example 1, except that the color reagent was replaced with malachite green and the white light complementary color was replaced with the orange complementary color.

[0119] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 4 。

[0120] Example 9

[0121] The perchlorate content was detected according to the detection method of Example 1, except that the color reagent was replaced with malachite green and the white light complementary color was replaced with the yellow - orange complementary color.

[0122] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 4 。

[0123] Example 10

[0124] The perchlorate content was detected according to the detection method of Example 1, except that the color developer was replaced with crystal violet and the white light complementary color light was replaced with red complementary color light.

[0125] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 5 .

[0126] Example 11

[0127] The perchlorate content was detected according to the detection method of Example 1, except that the color developer was replaced with crystal violet and the white light complementary color light was replaced with orange complementary color light.

[0128] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 5 .

[0129] Example 12

[0130] The perchlorate content was detected according to the detection method of Example 1, except that the color developer was replaced with rhodamine B and the white light complementary color light was replaced with green complementary color light.

[0131] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 6 .

[0132] Example 13

[0133] The perchlorate content was detected according to the detection method of Example 1, except that the color developer was replaced with rhodamine B and the white light complementary color light was replaced with purple complementary color light.

[0134] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 6 .

[0135] Example 14

[0136] The perchlorate content was detected according to the detection method of Example 1, except that in step (3), the 10 - 4 mol / L methylene blue solution was replaced with 10 -2 mol / L.

[0137] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 8 and Figure 9 .

[0138] Example 15

[0139] The perchlorate content was detected according to the detection method of Example 1, except that in step (3), the 10 -4 Replace the 10 -3 mol / L methylene blue solution with 10

[0140] The standard curves and correlation coefficients of the R value, G value, B value and perchlorate are shown in Figure 8 and Figure 9 .

[0141] Example 16

[0142] Detect the perchlorate content according to the detection method of Example 1. The difference is that in step (3), replace the 10 - 4 mol / L methylene blue solution with 5×10 -4 mol / L.

[0143] The standard curves and correlation coefficients of the R value and perchlorate are shown in Figure 8 and Figure 9 .

[0144] Example 17

[0145] Detect the perchlorate content according to the detection method of Example 1. The difference is that in step (3), replace the CH3COOH-CH3COONa buffer solution with a pH of 4.5 with a CH3COOH-CH3COONa buffer solution with a pH of 3.0.

[0146] The standard curves and correlation coefficients of the R value and perchlorate are shown in Figure 10 .

[0147] Example 18

[0148] Detect the perchlorate content according to the detection method of Example 1. The difference is that in step (3), replace the CH3COOH-CH3COONa buffer solution with a pH of 4.5 with a CH3COOH-CH3COONa buffer solution with a pH of 6.0.

[0149] The standard curves and correlation coefficients of the R value and perchlorate are shown in Figure 10 .

[0150] Example 19

[0151] Detect the perchlorate content according to the detection method of Example 1. The difference is that in step (3), replace the CH3COOH-CH3COONa buffer solution with a pH of 4.5 with a CH3COOH-CH3COONa buffer solution with a pH of 7.5.

[0152] The standard curves and correlation coefficients of the R value and perchlorate are shown in Figure 10 .

[0153] Example 20

[0154] The perchlorate content was detected according to the detection method of Example 1, except that in step (3), the CH3COOH-CH3COONa buffer solution with a pH of 4.5 was replaced with a CH3COOH-CH3COONa buffer solution with a pH of 9.0.

[0155] The standard curve and correlation coefficient of the R value with perchlorate are shown in Figure 10 。

[0156] Example 21

[0157] The perchlorate content was detected according to the detection method of Example 1, except that in step (3), the volume of dichloromethane was replaced with 0.50 mL.

[0158] The correlation coefficient corresponding to the standard curve of the R value and perchlorate is shown in Figure 11 。

[0159] Example 22

[0160] The perchlorate content was detected according to the detection method of Example 1, except that in step (3), the volume of dichloromethane was replaced with 0.75 mL.

[0161] The correlation coefficient corresponding to the standard curve of the R value and perchlorate is shown in Figure 11 。

[0162] Example 23

[0163] The perchlorate content was detected according to the detection method of Example 1, except that in step (3), the volume of dichloromethane was replaced with 1.25 mL.

[0164] The correlation coefficient corresponding to the standard curve of the R value and perchlorate is shown in Figure 11 。

[0165] Example 24

[0166] The perchlorate content was detected according to the detection method of Example 1, except that in step (3), the volume of dichloromethane was replaced with 1.50 mL.

[0167] The correlation coefficient corresponding to the standard curve of the R value and perchlorate is shown in Figure 11 。

[0168] From Figure 11 It can be seen that for the verification and determination of the standard curve at three interval points of perchlorate concentration of 0-100, 100-800, and 800-3000 μg / L, when the volume of dichloromethane is 1 mL (Example 1), the R values of the three intervals2 The values are all closest to 1.00, and the fitting effect is the best.

[0169] Comparative example

[0170] (1) Filter the impurities and microorganisms in the tap water sample through a 0.45μm filter membrane, collect it in a clean container, and store it in a 4°C refrigerator. It should be noted that 1 / 3 volume of air is reserved in the container to prevent the degradation of perchlorate by anaerobic microorganisms;

[0171] (2) Add 1 mL of CH3COOH-CH3COONa buffer solution with a pH of 4.5, 0.55 mL of 10 - 4 mol / L methylene blue solution and 5 mL of water sample into a 15 mL centrifuge tube, and make up the volume to 10 mL with ultrapure water; add 70 μL of methanol as a dispersant and 1 mL of dichloromethane as an extractant, shake vigorously for 30 s, then centrifuge at 4000 rmp for 5 min, and inject the lower-layer extraction phase taken out with a micro sampler into a 350 μL cuvette;

[0172] (3) Place the cuvette in a 3D printed light-shielding container with the light source turned on, use a white light fill light for fill light, use an iPhone13 mobile phone to take pictures of the extraction phase in the cuvette for sampling, extract the R value, G value, and B value 3 times each through the F color picker APP, take the average value, and establish a relationship curve with the concentration respectively. When the concentration of perchlorate is greater than 0 μg / L and less than or equal to 100 μg / L, the linear equation of the standard curve is y = -536.97x + 197.21, and the correlation coefficient R 2 = 0.9967; for the standard curve when the concentration of perchlorate is greater than 100 μg / L and less than or equal to 3000 μg / L, when the concentration of perchlorate is greater than 100 μg / L and less than or equal to 800 μg / L, the linear equation of the standard curve is y = -93.644x + 196.53, and the correlation coefficient R 2 = 0.9961; when the concentration of perchlorate is greater than 800 μg / L and less than or equal to 3000 μg / L, the linear equation of the standard curve is y = -36.254x + 154.44, and the correlation coefficient R 2 = 0.9987; Calculate twice the corresponding concentration according to the drawn standard curve, which is the content of perchlorate in the water sample.

[0173] Test example 1

[0174] Verify the precision and accuracy of the perchlorate determination system for different concentration ranges. The results of the method precision verification are shown in Table 1, and the results of the method accuracy verification are shown in Table 2.

[0175] Table 1

[0176]

[0177] Table 2

[0178]

[0179]

[0180] Samples with a perchlorate concentration of 0 mg / L were taken, and under the same experimental conditions as in Example 1, the digital signal values of the R channel were measured. The measurement was repeated 10 times, and the standard deviation (S) was calculated. The digital signal values of the R channel were substituted into the above standard curve equation to obtain the measured values, and the method detection limit was calculated. The method detection limit was found to be 0.004 mg / L. From the results of Table 1 and Table 2, it can be seen that for the determination system of perchlorate in different concentration ranges, both the precision and the accuracy are good.

[0181] Test Example 2

[0182] To test the practicability and accuracy of the method, the perchlorate content was detected according to the detection method of Example 1. The difference was that 6 ions that may interfere with the determination of perchlorate were added to the sample to be tested: nitrate ion, chloride ion, sulfate ion, magnesium ion, calcium ion, potassium ion, and the recovery rate of the reference material was measured. The results are shown in Table 3. It can be seen from Table 3 that under the interference of the common ion concentrations in environmental water samples, the recovery rate of the index measurement results is good, and the recovery rate is 98.16 - 103.44. This detection method has a high anti-interference ability.

[0183] Table 3

[0184]

[0185] Test Example 3

[0186] To test the practicability and accuracy of the method, the perchlorate content in three actual water samples (tap water, river water, pond water, and industrial wastewater) was analyzed on-site according to the detection method of Example 1. Each sample was measured 3 times and the average value was taken. The results are shown in Table 4.

[0187] Table 4

[0188]

[0189] From Figure 3 it can be seen that for perchlorate, whether at low concentration or high concentration, the fitting effect of this method is good. The low concentration shows a linear fit, and the high concentration shows a non-linear fit; the curve fitting R of the perchlorate concentration in both ranges 2 > 0.99. From Figures 4 - 7 it can be seen that the linear fitting effect of methylene blue and perchlorate under white light is the best and more practical. FromFigure 8 It can be seen that in the low concentration range of perchlorate content from 0 to 100 μg / L, using methylene blue solution with a concentration of 10-3 M can meet the requirements of linear range and precision. From Figure 9 It can be seen that in the high concentration range of perchlorate content from 100 to 3000 μg / L, it is a non-linear fitting. Using methylene blue solution with a concentration of 10 -4 M can meet the precision requirements within the detection range. From Figure 10 It can be seen that when the analysis signal is at pH = 4.5, its fitting degree is the highest, where R2 = 0.9922 and the linear fitting effect is the best. From Figure 11 It can be seen that when the extractant is 1 mL of dichloromethane by volume, the R 2 values in the three intervals are all closest to 1.00 and the fitting effect is the best.

[0190] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining each technical feature in any other suitable way. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for detecting perchlorate, characterized in that, It includes the following steps: (1) After filtering the water sample through a filter membrane, the sample to be tested is obtained and stored in a sealed container; (2) The sample to be tested and the color reagent are subjected to a color reaction, and after liquid-liquid extraction, an organic layer containing perchlorate is obtained; (3) The organic layer is photographed, and then the RGB signal channel values of the photographed image are extracted; When the concentration of perchlorate in the standard concentration is greater than 0 μg / L and less than or equal to 100 μg / L, with the concentration of perchlorate in the perchlorate aqueous solution of the standard concentration as the abscissa x and the R value of the perchlorate aqueous solution image as the ordinate y, a standard curve of the concentration and R value of perchlorate in the perchlorate aqueous solution is established. The linear equation of the standard curve is y = ax + b, and the linear correlation coefficient > 0.

99. The R value of the sample to be tested is substituted into the standard curve to calculate the content of perchlorate in the sample to be tested; When the concentration of perchlorate at the standard concentration is greater than 100 μg / L and less than or equal to 3000 μg / L, taking the logarithm of 10 times the concentration of perchlorate in the aqueous solution of perchlorate at the standard concentration as the abscissa x and the R value of the aqueous solution image of perchlorate as the ordinate y, a standard curve of the logarithm of 10 times the concentration of perchlorate in the aqueous solution of perchlorate and the R value is established. The quadratic fitting equation of the standard curve is y = Ax 2 - + Bx + C, the correlation coefficient > 0.

99. Substitute the R value of the sample to be measured into the standard curve to calculate the content of perchlorate in the sample to be measured.

2. The detection method according to claim 1, characterized in that, When the concentration of perchlorate in the standard concentration is greater than 0 μg / L and less than or equal to 100 μg / L, a is -700 to -500 and b is 100 - 300 in the linear equation; Preferably, when the concentration of perchlorate in the standard concentration is greater than 100 μg / L and less than or equal to 3000 μg / L, A is -10 to -5, B is -15 to -10, and C is 100 - 300 in the linear equation.

3. The detection method according to claim 1, wherein, In step (1), the volume ratio of the sample to be tested to air in the sealed container is 1 - 2:1; Preferably, the storage conditions include at least: 0 - 4 °C; Preferably, the pore size of the filter membrane is 0.4 - 0.5 μm; Preferably, the water sample is selected from at least one of well water, tap water, river water, rural ditch water, and industrial wastewater.

4. The detection method according to any one of claims 1 to 3, characterized in that, In step (2), the color reagent is selected from at least one of methylene blue, malachite green, crystal violet, and rhodamine B, and preferably methylene blue; Preferably, the developer is an aqueous solution of a developer, and the concentration of the developer in the aqueous solution of the developer is 5×10 -4 -10 - 2 mol / L, more preferably 0.9 - 1.1×10 -4 mol / L; Preferably, the volume ratio of the sample to be tested to the color reagent is 1:9 - 10.

5. The detection method according to claim 4, wherein Before the color reaction, a buffer solution is added to the sample to be tested; Preferably, the buffer solution is selected from CH3COOH - CH3COONa buffer solution and / or PBS buffer solution, and more preferably CH3COOH - CH3COONa buffer solution; Preferably, the pH of the buffer solution is 4 - 7.5, and more preferably 4 - 5; Preferably, the volume ratio of the buffer solution to the sample to be tested is 1:0.5 - 0.

6.

6. The detection method according to any one of claims 1 to 3, characterized in that, In step (2), the process of liquid-liquid extraction includes: mixing the reaction solution obtained from the color reaction, the dispersant, and the extractant and then separating; Preferably, the dispersant is methanol and / or ethanol, and more preferably methanol; the extractant is selected from at least one of dichloromethane, ethyl acetate, toluene, and chloroform, and more preferably dichloromethane.

7. The detection method according to claim 6, characterized in that The separation is centrifugal separation; Preferably, the separation conditions include at least: the rotation speed is 4000 - 5000 rpm and the time is 4 - 8 min.

8. The detection method according to any one of claims 1 to 3, characterized in that In step (3), the photographing is carried out in a light-shielding device, and the organic layer is irradiated with a light source.

9. The detection method according to claim 8, wherein, The light source is white light.

10. The detection method according to any one of claims 1 to 3, characterized in that, In step (3), the RGB signal channel value selects the R value.

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