A detection reagent and detection method suitable for mercury concentration in complex water environment

Abstract

The present application discloses a detection reagent and a detection method thereof suitable for mercury concentration in a complex water environment, wherein the detection reagent includes a first reagent, a second reagent and a third reagent; the first reagent is a developer, and by weight percentage, includes: cadmium reagent 0.005%~0.5%, Triton X-114 2%-20%, ethyl acetate 10%-60%, ethanol 20%-80%, sodium hydroxide 0.1-1%; the second reagent is an alkaline buffer solution with a pH range of 10.08-12.10; the third reagent is a complexing agent, and by weight percentage, contains: ammonium citrate 5-50%, potassium sodium tartrate 1-15%, glycine 0.1-10%, and the solvent is water. The present application has a simple operation method, strong anti-interference ability, and can accurately detect the content of mercury in complex water bodies.

Description

Technical Field

[0001] The present invention relates to the technical field of water quality detection, and in particular to a detection reagent and a detection method thereof suitable for mercury concentration in a complex water environment. Background Art

[0002] Mercury pollution in water bodies caused by human activities mainly comes from wastewater discharged by industries such as chlor-alkali, plastics, batteries, and electronics, as well as discarded medical devices. Mercury is the only heavy metal that can migrate and transform in the complete ecosystem of water bodies, soil, atmosphere, and biosphere. Mercury discharged into the atmosphere or soil by human activities will also return to water bodies through the water cycle. Mercury in water bodies is most likely to cause health hazards to humans. Mercury causes damage to the human brain, nerves, kidneys, and liver, and can even cause coma and death. It has become one of the environmental pollutants that has attracted widespread attention worldwide. In recent years, due to the frequent occurrence of vicious environmental pollution incidents caused by improper mercury emissions, the control of mercury pollution in industrial production and real-time monitoring are crucial to global mercury control actions, and accurate detection of mercury content in water bodies is very important.

[0003] At present, the main methods for mercury detection include cold atomic absorption, cold atomic fluorescence, inductively coupled plasma (ICP), atomic absorption spectroscopy, spectrophotometry, etc. Among them, cold atomic absorption and cold atomic fluorescence require complex purification processes, and dithizone colorimetry is a more commonly used method in spectrophotometry, which is the most widely studied and applied in the color analysis of mercury, but the stability of dithizone colorimetry is not good enough.

[0004] In short, the existing detection methods have poor anti-interference ability for complex water bodies and cannot accurately detect the mercury content in complex water bodies. Summary of the invention

[0005] The present application provides a detection reagent and a detection method suitable for mercury concentration in a complex water environment. The operation method is simple, the anti-interference ability is strong, and the mercury content in the complex water body can be accurately detected.

[0006] A detection reagent suitable for mercury concentration in a complex water environment, comprising a first reagent, a second reagent and a third reagent;

[0007] The first reagent is a color developer, which includes, by weight percentage: 0.005% to 0.5% of cadmium reagent, 2% to 20% of Triton X-114, 10% to 60% of ethyl acetate, 20% to 80% of ethanol, and 0.1% to 1% of sodium hydroxide;

[0008] The second reagent is an alkaline buffer solution with a pH value ranging from 10.08 to 12.10;

[0009] The third reagent is a complexing agent, which contains, by weight percentage, 5-50% ammonium citrate, 1-15% potassium sodium tartrate, 0.1-10% glycine, and the solvent is water.

[0010] In the present application, on the one hand, a cadmium reagent is used as a color developer. The cadmium reagent generates an orange complex with divalent mercury ions in the water body, but the cadmium reagent is not well soluble and it is difficult to make a stable water sample reagent. In this regard, the present application uses Triton X-114 as a solubilizing agent and then adds ethyl acetate to significantly improve the solubility of the cadmium reagent. At the same time, the amount of sodium hydroxide used can be reduced, and the cadmium reagent is configured into a stable color developer solution, which is convenient for on-site or field detection.

[0011] On the other hand, the present application selects an alkaline buffer solution with a pH value in the range of 10.08-12.10, so that the pH of the reaction system is maintained in a more appropriate range, thereby preliminarily shielding some interfering ions, especially the interference of other metal ions.

[0012] On the other hand, the complexing agent of the present application further strengthens the anti-interference ability of the detection reagent and method of the present application. The appropriate pH range can initially shield some interfering ions, but there are still some interfering ions that will react with the cadmium reagent to develop color, and after these interfering ions react with the cadmium reagent, under the condition of adding the complexing agent, they can be captured by the complexing agent of the present application through the complexing method, so that they are separated from the cadmium reagent and further remove their interference with the present reaction. And the complexing agent of the present application will not destroy the binding reaction of the cadmium reagent and the mercury ion.

[0013] Finally, the order of adding the complexing agent cannot be changed at will and must be added in the last step. If it is not added at the end, the absorbance value of the entire reaction system will be low and the reaction sensitivity will be reduced. This may be related to a supramolecular effect between the various reaction reagents and reactants.

[0014] In summary, the detection reagent of the present application optimizes the color developer solution to improve the stability of the color developer, and then selects a suitable pH buffer, cooperates with a specific chelating agent, and strictly controls the order of addition of each reagent, so as to significantly improve the actual anti-interference ability of the detection.

[0015] Optionally, the developer comprises, by weight percentage, 0.01% to 0.1% cadmium reagent, 5% to 10% Triton X-114, 30% to 50% ethyl acetate, 40% to 60% ethanol, and 0.5% to 1% sodium hydroxide.

[0016] The ethanol used in this application, unless otherwise specified, is anhydrous ethanol.

[0017] Optionally, the second reagent is an alkaline buffer solution with a pH value in the range of 10.50-11.28, which is more conducive to masking the interference of other metal ions.

[0018] Optionally, the alkaline buffer may be a buffer system of borax and sodium hydroxide, a buffer system of boric acid and sodium hydroxide, or a buffer system of glycine and sodium hydroxide.

[0019] Optionally, the complexing agent contains, by weight percentage, 5-15% ammonium citrate, 1-5% potassium sodium tartrate, 0.3-0.6% glycine, and the solvent is water.

[0020] Most preferably:

[0021] The color developer comprises, by weight percentage, 0.05% cadmium reagent, 9% Triton X-114, 40% ethyl acetate, 50% ethanol, and 0.95% sodium hydroxide;

[0022] The alkaline buffer solution has a pH value ranging from 10.50 to 11.28;

[0023] The complexing agent contains, by weight percentage, 10% ammonium citrate, 3% potassium sodium tartrate, 0.5% glycine, and the remainder is water.

[0024] The present application also provides a method for detecting mercury concentration in water using the detection reagent, comprising:

[0025] Put the water sample to be tested into a colorimetric bottle, then add the first reagent to the water sample to be tested, mix well, add the second reagent, mix well, then add the third reagent, mix well, let stand for reaction for 4 to 6 minutes, and obtain a reaction solution;

[0026] The absorbance value of the reaction solution at 470 nm is detected, and the absorbance value is substituted into the standard curve to calculate the mercury concentration in the water sample to be tested.

[0027] The detection reagents of the present application need to be added in the order of the first reagent, the second reagent and the third reagent. The color developer and the buffer cannot be interchanged. For example, if the alkaline buffer is added first, mercury ions will form precipitation under alkaline conditions, resulting in inaccurate determination. And the order of adding the complexing agent cannot be changed. If it is not added last, the absorbance value of the entire reaction system will be low, and the reaction sensitivity will be reduced.

[0028] Optionally, the water sample to be tested is a natural water sample, including land water and sea water, and land water includes but is not limited to electroplating wastewater, tap water, pure water, river water, etc.

[0029] Optionally, the concentration of water quality mercury in the water sample to be tested is 0-2 mg / L. That is, the detection reagent of the present application can accurately detect natural water samples containing water quality mercury concentration within 0-2 mg / L.

[0030] Optionally, based on 5 mL of the water sample to be tested, the amount of the first reagent added is 0.2-0.8 mL, the amount of the second reagent added is 1-3 mL, and the amount of the third reagent added is 1-3 mL.

[0031] Optionally, the standard curve is: y=1.4894x+0.0018, wherein x is the absorbance value, and y is the mercury content in the water sample, in mg / L.

[0032] The present application also provides a method for measuring trace mercury concentration in water using the detection reagent, comprising:

[0033] Enrichment step:

[0034] Add potassium iodate absorption liquid to the absorption bottle; add a water sample to the reaction bottle, and then add stannous chloride solution; connect the air outlet of the reaction bottle to the air inlet of the absorption bottle through a pipeline, and the air outlet of the absorption bottle is connected to the air sampler through a pipeline, and the potassium iodate absorption liquid enriched for 20 to 40 minutes is used as the water sample to be tested;

[0035] Testing steps:

[0036] Pipette a portion of the water sample to be tested into a colorimetric bottle, then add the first reagent to the water sample to be tested, mix well, add the second reagent, mix well, then add the third reagent, mix well, and let stand for reaction for 4 to 6 minutes to obtain a reaction solution;

[0037] The absorbance value of the reaction solution at 470 nm is detected, and the absorbance value is substituted into the standard curve to calculate the mercury concentration in the water sample to be tested.

[0038] Optionally, based on 250 mL of water sample in the reaction bottle, 10 mL of potassium iodate absorption liquid in the absorption bottle, and 5 mL of water sample to be tested, the amount of the first reagent added is 0.2-0.8 mL, the amount of the second reagent added is 1-3 mL, and the amount of the third reagent added is 1-3 mL.

[0039] Optionally, the concentration of mercury in the water sample is 0-100 ug / L.

[0040] If the water sample volume in the reaction bottle reaches 2.5L or 25L (the volume of the absorption liquid remains unchanged), the detection range of mercury can be further reduced to 0-10ug / L or 0-1ug / L, and the order of adding reagents remains unchanged.

[0041] Optionally, the potassium iodate absorption liquid is a mixed liquid with a mass ratio of potassium iodate: concentrated sulfuric acid: water of 4:0.6:100;

[0042] Optional. The stannous chloride solution is a mixed solution with a mass ratio of stannous chloride: concentrated sulfuric acid: water of 10:10:40. The volume ratio of the added amount of the stannous chloride solution to the water sample in the reaction bottle is 1:100.

[0043] Optionally, the flow rate of the air sampler is adjusted to 400 mL / min.

[0044] Optionally, the standard curve is: y=79.793x-0.4763, wherein x is the absorbance value, and y is the mercury content in the water sample, in units of ug / L.

[0045] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0046] (1) Common methods for determining mercury include cold atomic absorption spectrophotometry, cold atomic fluorescence spectrometry, inductively coupled plasma, atomic absorption spectrometry, etc., all of which require expensive instruments, are cumbersome to operate, have high requirements on the professional skills of operators, and can only be performed in laboratories. The detection reagent of this application has good stability and strong anti-interference ability. It can be directly used for on-site or field detection in conjunction with a portable colorimeter or water quality detector; and the detection cost is low and the timeliness is good.

[0047] (2) The detection reagent of the present application can accurately detect the mercury concentration in complex water bodies such as electroplating wastewater, tap water, seawater, river water, etc., with a detection range of 0.1~2mg / L; at the same time, with the enrichment step, taking 250mL of water sample as an example, trace mercury detection in water can be performed, with a detection range of 0-100ug / L. If the sampling water sample is further increased, such as 1L, the detection sensitivity can be further improved.

[0048] (3) It is generally believed that, in the case of an enrichment step, mercury ions are converted into mercury molecules and carried into the absorption liquid by the gas, which is relatively further purified. It is rarely considered that other ions in the actual water sample may also enter the absorption liquid through the enrichment step, causing interference with the mercury determination. Therefore, there are no or few interference studies on mercury detection using enrichment methods in the current literature or reports. However, the present application found in the study that if the chelating agent of the present application is not added to the actual water sample, the spike recovery is not satisfactory, with large deviations, especially at low concentrations, with an error of more than 1 times (see Table 4). BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is the standard curve diagram of Example 1;

[0050] Figure 2It is the standard curve diagram of Example 2;

[0051] Figure 3 This is the standard curve diagram of Comparative Example 1. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0054] Example 1

[0055] Detection reagents:

[0056] Color developer: by weight percentage, including: cadmium reagent 0.05%, Triton X-114 9%, ethyl acetate 40%, anhydrous ethanol 50%, sodium hydroxide 0.95%.

[0057] Alkaline buffer solution: pH value is 11.02, and the buffer system is a buffer system of borax and sodium hydroxide.

[0058] Complexing agent: by weight percentage, ammonium citrate 10%, potassium sodium tartrate 3%, glycine 0.5%, and the rest water.

[0059] The reagents used are all commercially available products, and the cadmium reagent can be a cadmium reagent with CAS number: 5392-67-6.

[0060] Production of the song:

[0061] Mercury marking solution:

[0062] Mercury standard solution (1000 mg / L): Use Aladdin commercially available standard solution (product number: M115416-50ml).

[0063] Mercury marking intermediate liquid:

[0064] Mercury intermediate solution (10 mg / L): Pipette 1 mL of mercury standard solution (1000 mg / L) into a 100 mL volumetric flask, dilute to the mark with water, and shake well.

[0065] Preparation of mercury standard concentration solution:

[0066] Mercury solution (0 mg / L): pure water

[0067] Mercury working solution (0.5 mg / L): Take 5 mL of mercury intermediate solution (10 mg / L) and dilute to 100 mL with pure water.

[0068] Mercury working solution (1 mg / L): Take 10 mL of mercury intermediate solution (10 mg / L) and dilute to 100 mL with pure water.

[0069] Mercury working solution (1.5 mg / L): Take 15 mL of mercury intermediate solution (10 mg / L) and dilute to 100 mL with pure water.

[0070] Mercury working solution (2.0 mg / L): Take 20 mL of mercury intermediate solution (10 mg / L) and dilute to 100 mL with pure water.

[0071] Turn on the water quality detector (such as ZY-360 multi-parameter water quality analyzer, Zhejiang Luheng Environmental Technology Co., Ltd.), and select the mercury measurement position or 470nm wavelength.

[0072] Add 5 mL of different concentrations of mercury standard concentration solution to the colorimetric bottle, add 0.5 mL of color developer (first reagent), shake well, add 2.5 mL of alkaline buffer (second reagent), shake well, add 2 mL of complexing agent (third reagent), cover and shake well, and let it react for 5 minutes. Put the reacted colorimetric bottle into the detection chamber for detection, and use pure water as a blank control. After the test, press and hold the power key to turn off the instrument.

[0073] With the absorbance value as the horizontal axis and the mercury content as the vertical axis, a standard curve is drawn. Figure 1 As shown, y=1.4894x+0.0018, where x is the absorbance value and y is the mercury content in the water sample, in mg / L.

[0074] Testing process:

[0075] Turn on the water quality detector (such as ZY-360 multi-parameter water quality analyzer, Zhejiang Luheng Environmental Technology Co., Ltd.), and select the mercury measurement position or 470nm wavelength.

[0076] Add 5 mL of the water sample to be tested into the colorimetric bottle, add 0.5 mL of the color developer (first reagent), shake well, add 2.5 mL of the alkaline buffer (second reagent), shake well, add 2 mL of the complexing agent (third reagent), cover and shake well, and let it react for 5 minutes. Put the reacted colorimetric bottle into the detection chamber for detection, and use pure water as a blank control. After the test, press and hold the power key to turn off the instrument.

[0077] Test results:

[0078] The water samples to be tested were directly collected from pure water, electroplating wastewater, tap water, seawater and river water for spike recovery test. The spike recovery rates are shown in Table 1. From the results in the table, it can be seen that the spike recovery rates are between 94.34% and 105.97%.

[0079] Table 1

[0080]

[0081] Comparative Example 1

[0082] Compared with Example 1, during the detection process, the order of adding reagents is modified to first add the complexing agent (the third reagent), then add the alkaline buffer solution (the second reagent), and finally add the color developer (the third reagent). The water samples are collected from pure water and electroplating wastewater. The rest is the same as Example 1.

[0083] The test results showed that pure water samples were not affected, but the spiked recovery rate of actual water samples was poor and the accuracy was affected. The lowest spiked recovery rate was only 9% and the highest was only 84.84% (Table 2).

[0084] Table 2

[0085]

[0086] It can be seen from the results of Example 1 and Comparative Example 1 that the detection reagent of the present application, according to the order of adding the color developer, the alkaline buffer solution, and the chelating agent, can accurately detect the mercury concentration in complex water bodies such as electroplating wastewater, tap water, seawater, river water, etc., and the detection range is within 0.1~2mg / L.

[0087] Example 2

[0088] Test reagents are the same as in Example 1

[0089] Production of the song:

[0090] Mercury marking solution:

[0091] Mercury standard solution (1000 mg / L): Use Aladdin commercially available standard solution (product number: M115416-50ml).

[0092] Mercury marking intermediate liquid:

[0093] Mercury intermediate solution (10 mg / L): Pipette 1 mL of mercury standard solution (1000 mg / L) into a 100 mL volumetric flask, dilute to the mark with water, and shake well.

[0094] Preparation of mercury standard concentration solution:

[0095] Mercury solution (0μg / L): pure water

[0096] Mercury working solution (10μg / L): Take 25mL of mercury intermediate solution (100μg / L) and make up to 250mL with pure water.

[0097] Mercury working solution (30μg / L): Take 0.75mL of mercury intermediate solution (10mg / L) and make up to 250mL with pure water.

[0098] Mercury working solution (50μg / L): Take 1.25mL of mercury intermediate solution (10mg / L) and dilute to 250mL with pure water.

[0099] Mercury working solution (100 μg / L): Take 2.5 mL of mercury intermediate solution (10 mg / L) and dilute to 250 mL with pure water.

[0100] Testing process:

[0101] (1) The enrichment reaction device includes a reaction bottle, an absorption bottle (needs to be used in a dry state), an air sampler and several rubber tubes. The air sampler adopts the DES-C2 air sampler of DEERSI / Deersi, with a flow range of 100-1000mL / min, a timing range of 0-99min, a working temperature of -10℃-40℃, and a vacuum pressure of ≥3000Pa. The air outlet of the reaction bottle is connected to the air inlet of the absorption bottle through a rubber tube, and the air outlet of the absorption bottle is connected to the air inlet of the air sampler through a rubber tube.

[0102] Add 10 mL of potassium iodate absorption solution (the mass ratio of potassium iodate: concentrated sulfuric acid: water is 4:0.6:100) to the absorption bottle; add 250 mL of standard mercury concentration solution of different concentrations to the reaction bottle, and then add 2.5 mL of stannous chloride solution (the mass ratio of stannous chloride: concentrated sulfuric acid: water is 10:10:40) to the reaction bottle, shake well, turn on the air sampler switch, adjust the flow rate to 400 mL / min, and enrich for 30 minutes.

[0103] (2) After the enrichment reaction is completed, remove the absorption bottle and set aside.

[0104] (3) Turn on the water quality detector (such as ZY-360 multi-parameter water quality analyzer, Zhejiang Luheng Environmental Technology Co., Ltd.), select the mercury measurement gear or 470nm wavelength. Take 5 mL of the absorption solution corresponding to the standard concentration of mercury in different concentrations into the colorimetric bottle, add 0.5 mL of the color developer (first reagent), shake well, add 2.5 mL of alkaline buffer (second reagent), shake well, add 2 mL of the complexing agent (third reagent), cover and shake well, and let it react for 5 minutes. Put the reacted colorimetric bottle into the detection chamber for detection, and use pure water as the blank water sample, repeat the above steps as a blank control; after the test, press and hold the power key to turn off the instrument.

[0105] With the absorbance value as the horizontal axis and the mercury content in the standard solution as the vertical axis, a standard curve is drawn. Figure 2 As shown, y=79.793x-0.4763, where x is the absorbance value and y is the mercury content in the water sample, in ug / L.

[0106] When testing actual water samples, the testing process is the same as above, except that 250 mL of the water sample to be tested is added to the reaction bottle, and the obtained absorbance value is substituted into the above standard curve to calculate the mercury concentration in the water sample to be tested.

[0107] Test results:

[0108] Pure water, electroplating wastewater, tap water, seawater and river water were taken respectively for spike recovery test. The spike recovery rate results are shown in Table 3. From the results in Table 3, it can be seen that the spike recovery is between 93.37% and 115.06%.

[0109] Table 3

[0110]

[0111] Comparative Example 2

[0112] Compared with Example 2, the difference is that no complexing agent (third reagent) is added, and the rest is the same as Example 2.

[0113] The standard curve is as follows Figure 3 shown.

[0114] Pure water, electroplating wastewater, tap water, seawater and river water were taken for spike recovery tests. The spike recovery rate results are shown in Table 4. From the results in Table 4, it can be seen that the spike recovery is between 94.61-287.58%. The actual water sample test values ​​are all high and the deviation values ​​are large, so it is impossible to obtain accurate mercury content values.

[0115] Table 4

[0116]

[0117] It is generally believed that in the case of an enrichment step, mercury ions are converted into mercury molecules and carried into the absorption liquid by the gas, which is relatively further purified. It is rarely considered that other ions in the actual water sample may also enter the absorption liquid through the enrichment step, causing interference with the mercury determination. Therefore, there are no or few interference studies on mercury detection using enrichment methods in the current literature or reports. However, the present application found in the study that if the chelating agent of the present application is not added to the actual water sample, the spike recovery is not satisfactory, with large deviations, especially at low concentrations, with an error of more than 1 times (see Table 4).

[0118] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A detection reagent suitable for mercury concentration in complex water environments, characterized in that: comprising a first reagent, a second reagent and a third reagent; The first reagent is a color developer, which includes, by weight percentage: 0.005% to 0.5% cadmium reagent, 2% to 20% Triton X-114, 10% to 60% ethyl acetate, 20% to 80% ethanol, and 0.1% to 1% sodium hydroxide; The second reagent is an alkaline buffer solution with a pH value ranging from 10.50 to 11.28; The third reagent is a complexing agent, which contains, by weight percentage, 5-15% ammonium citrate, 1-5% potassium sodium tartrate, 0.3-0.6% glycine, and the solvent is water.

2. The detection reagent according to claim 1, characterized in that The color developer comprises, by weight percentage, 0.01% to 0.1% of cadmium reagent, 5% to 10% of Triton X-114, 30% to 50% of ethyl acetate, 40% to 60% of ethanol, and 0.5% to 1% of sodium hydroxide.

3. A method for detecting mercury concentration in water using the detection reagent according to claim 1, characterized in that: include: Put the water sample to be tested into a colorimetric bottle, then add the first reagent to the water sample to be tested, mix well, add the second reagent, mix well, then add the third reagent, mix well, let stand for 4-6 minutes to react, and obtain a reaction solution; the water sample to be tested is a natural water sample; the concentration of water quality mercury in the water sample to be tested is 0-2 mg / L; The absorbance value of the reaction solution at 470 nm is detected, and the absorbance value is substituted into the standard curve to calculate the mercury concentration in the water sample to be tested.

4. The detection method according to claim 3, characterized in that: Based on 5 mL of the water sample to be tested, the amount of the first reagent added is 0.2-0.8 mL, the amount of the second reagent added is 1-3 mL, and the amount of the third reagent added is 1-3 mL.

5. A method for detecting trace mercury concentration in water using the detection reagent according to claim 1, characterized in that: include: Enrichment step: Add potassium iodate absorption liquid to the absorption bottle; add a water sample to the reaction bottle, wherein the concentration of mercury in the water sample is 0-100ug / L; then add stannous chloride solution; connect the air outlet of the reaction bottle to the air inlet of the absorption bottle through a pipeline, connect the air outlet of the absorption bottle to the air sampler through a pipeline, turn on the air sampler, and use the potassium iodate absorption liquid enriched for 20-40 minutes as the water sample to be tested; Testing steps: Pipette a portion of the water sample to be tested into a colorimetric bottle, then add the first reagent to the water sample to be tested, mix well, add the second reagent, mix well, then add the third reagent, mix well, and let stand for reaction for 4 to 6 minutes to obtain a reaction solution; The absorbance value of the reaction solution at 470 nm is detected, and the absorbance value is substituted into the standard curve to calculate the mercury concentration in the water sample to be tested.

6. The detection method according to claim 5, characterized in that: Based on the water sample in the reaction bottle being 250 mL, the potassium iodate absorption liquid in the absorption bottle being 10 mL, and 5 mL of the water sample to be tested being transferred, the amount of the first reagent added is 0.2-0.8 mL, the amount of the second reagent added is 1-3 mL, and the amount of the third reagent added is 1-3 mL.

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