An on-line method for studying interference and auxiliary agents by atomic fluorescence

Abstract

The present invention discloses a system and method for on-line study of interference and auxiliary agents by atomic fluorescence, including an atomic fluorescence spectrometer, wherein the atomic fluorescence spectrometer is connected to a solution to be measured and a reducing agent through a first peristaltic pump. It is characterized in that a solution concentration on-line preparation system is connected through a tee device on the pipeline where the solution to be measured is connected to the first peristaltic pump; the solution concentration on-line preparation system is used to on-line prepare interference element solutions with different concentrations and auxiliary agent solutions with different concentrations for different solutions to be measured. The present invention minimizes the consumption of reagents and saves operation time, and flexibly investigates the effects of interference, masking, sensitization, etc. at different concentration points, making the experiment more flexible and easier to carry out fine investigation work.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical chemistry, and particularly to a method for on-line studying interference and additives by atomic fluorescence. Background Art

[0002] Atomic fluorescence spectrometry has been widely used in the determination of trace elements such as arsenic, antimony, bismuth, mercury, selenium, etc., and is also widely used in the determination of trace lead and cadmium. Its basic principle is that in an acidic medium, the element to be measured reacts with a strong reducing agent such as potassium borohydride (or sodium borohydride) to form a hydride gas or atom. The hydride molecules form ground-state atoms in an argon-hydrogen flame and generate atomic fluorescence under the excitation of the emitted light of the element lamp. The fluorescence intensity is related to the concentration of the element to be measured, and the concentration of the measured element is obtained by measuring its fluorescence intensity.

[0003] When using atomic fluorescence spectrometry to determine trace arsenic, antimony, bismuth, mercury, selenium, lead, cadmium, etc., for different types of samples, when establishing a determination method, it is necessary to examine whether the matrix components of the samples interfere with the elements to be measured and the degree of interference, and then take targeted measures such as adding masking agents or complexing agents to reduce interference. For example, for arsenic element, the interference of copper ions and lead ions in the sample needs to be considered during testing.

[0004] The method of using atomic fluorescence spectrometry to examine the interference of sample elements is usually to prepare a series of standard solutions of the element to be measured with the same concentration, and then add different amounts of interference element solutions respectively, and measure the change in the fluorescence signal intensity of the element to be measured to obtain the interference situation. The main method of adding additives such as masking agents or complexing agents by atomic fluorescence spectrometry is also to pre-add additives such as masking agents (or complexing agents) in the reducing agent solution or sample solution.

[0005] The biggest defect of this operation technique for examining interference and adding additives is the waste of reagents and the cumbersome operation. To examine one interference element, it is necessary to prepare more than a dozen or even dozens of standard solutions with different concentration points, and then add different amounts of interference element solutions and make up the volume for determination, which requires the consumption of reagents such as standard solutions of the element to be measured and high-purity hydrochloric acid. Calculated according to the examination of the interference of more than a dozen matrix elements for one element, hundreds of determination solutions need to be prepared, and the consumption of reagents is astonishing. The preparation is cumbersome and time-consuming.

[0006] In view of the deficiencies in the operation technique of using atomic fluorescence to examine interference, it is necessary to design a method that can meet the needs of interference examination or on-line addition of additives, but can save reagents and time to a large extent, so as to reduce the actual workload and save reagents. Summary of the Invention

[0007] In order to investigate an interfering element, it is necessary to prepare standard solutions with more than a dozen or even dozens of different concentration points, and then add different amounts of interfering element solutions and make up the volume for determination. This requires the consumption of reagents such as standard solutions of the element to be measured and high-purity hydrochloric acid. Calculated according to the investigation of more than a dozen matrix element interferences for one element, hundreds of determination solutions need to be prepared. The consumption of reagents is astonishing, and there are disadvantages such as cumbersome preparation time and long time consumption. Therefore, a method that can meet the needs of interference investigation or online addition of additives, but can greatly save reagents and time, is provided to achieve the purpose of reducing the actual workload and saving reagents.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] An atomic fluorescence online system for studying interference and additives includes an atomic fluorescence spectrometer. The atomic fluorescence spectrometer is connected to a solution to be measured and a reducing agent through a first peristaltic pump. A solution concentration online preparation system is connected to the pipeline connecting the solution to be measured and the first peristaltic pump through a three-way device.

[0010] The solution concentration online preparation system is used to online prepare interfering element solutions and additive solutions with different concentrations for different solutions to be measured.

[0011] An atomic fluorescence online method for studying interference and additives uses the following formula to proportion the concentration of the interfering element solution or the additive solution;

[0012]

[0013] Note: C 0 is the original concentration of the interfering element solution or the additive solution, with the unit of μg / mL;

[0014] C 1 is the concentration of the interfering element solution or the additive solution in the premixing pool, with the unit of μg / mL;

[0015] When extracting the interfering element solution or the additive solution, the pump speed of the speed-regulating peristaltic pump is a;

[0016] When extracting the dilution solution, the pump speed of the speed-regulating peristaltic pump is c;

[0017] The inner diameter of the first pipeline is d, and the inner diameter of the second pipeline is b;

[0018] The working time of the speed-regulating peristaltic pump for extracting the interfering element solution and the dilution solution is the same; or

[0019] The working time of the speed-regulating peristaltic pump for extracting the additive solution and the dilution solution is the same;

[0020] When b, d, and the operating time of the speed-adjustable peristaltic pump are fixed values, a and c can be adjusted to adjust the concentration of the interfering element solution or the additive solution in the premixing tank.

[0021] A system and method for on-line study of interference and additives by atomic fluorescence provided by the present invention further have the following technical features:

[0022] For example, in a system for on-line study of interference and additives by atomic fluorescence provided in an embodiment of the present disclosure, the on-line solution concentration preparation system includes a speed-adjustable peristaltic pump and a premixing tank. The speed-adjustable peristaltic pump, the interfering element solution, and the premixing tank are connected through a first pipeline. The speed-adjustable peristaltic pump, the dilution solution, and the premixing tank are connected through a second pipeline. The speed-adjustable peristaltic pump pumps the interfering element solution and the dilution solution into the premixing tank to mix and adjust the concentration, and the premixing tank is connected to a three-way device.

[0023] For example, in a system for on-line study of interference and additives by atomic fluorescence provided in an embodiment of the present disclosure, the on-line solution concentration preparation system includes a speed-adjustable peristaltic pump and a premixing tank. The speed-adjustable peristaltic pump, the additive solution, and the premixing tank are connected through a first pipeline. The speed-adjustable peristaltic pump, the dilution solution, and the premixing tank are connected through a second pipeline. The speed-adjustable peristaltic pump pumps the additive solution and the dilution solution into the premixing tank to mix and adjust the concentration, and the premixing tank is connected to a three-way device.

[0024] Compared with the prior art, the present invention provides a system and method for on-line study of interference and additives by atomic fluorescence, having the following beneficial effects:

[0025] 1. By designing a method for on-line study of the dosage of interference and additives, the dosage of reagents is minimized and the operation time is saved to the greatest extent, and the effects of interference, masking, sensitization, etc. at different concentration points can be flexibly investigated and studied, making the experiment more flexible and easier to carry out fine investigation and research work.

[0026] 2. The present invention retains the original instrument and equipment to the greatest extent without damaging the good test performance of the original equipment. It can be used immediately after connection and restored to the original sampling state when not in use, which is flexible and convenient.

[0027] 3. The present invention can not only be used in atomic fluorescence spectrometry, but also be applied to inductively coupled plasma emission spectrometry to carry out research work on the interference of matrix elements (such as silicon, aluminum, iron, potassium, sodium, calcium, magnesium, etc.) in emission spectrometry. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present disclosure and do not limit the present disclosure.

[0029] Figure 1Schematic diagram of a system and method for online study of interference and additives by atomic fluorescence in the present invention;

[0030] In the figure:

[0031] 1. First peristaltic pump; 2. Atomic fluorescence spectrometer; 3. Test element solution; 4. Reducing agent; 5. Interference element solution; 6. Dilution solution; 7. Speed-regulating peristaltic pump; 8. Premixing pool; 9. Three-way device; 10. First pipeline; 11. Second pipeline; 12. Additive solution. Specific embodiments

[0032] To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0033] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure shall have the ordinary meanings understood by those of ordinary skill in the art to which the present disclosure pertains. The "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or items appearing before this term cover the elements or items listed after this term and their equivalents, without excluding other elements or items.

[0034] Embodiment 1

[0035] Referring to Figure 1 as shown, a system for online study of interference and additives by atomic fluorescence includes an atomic fluorescence spectrometer 2, and the atomic fluorescence spectrometer 2 is connected to a test element solution 3 and a reducing agent 4 through a first peristaltic pump 1. A solution concentration online preparation system is connected to the pipeline where the test element solution 3 is connected to the first peristaltic pump 1 through a three-way device 9.

[0036] The solution concentration online preparation system is used to online prepare interference element solutions 5 with different concentrations and additive solutions 12 with different concentrations for different test element solutions 3.

[0037] The solution concentration online preparation system includes a speed-regulating peristaltic pump 7 and a premixing pool 8.

[0038] The speed-regulating peristaltic pump 7, the interference element solution 5 (additive solution 12) and the premixing pool 8 are connected through a first pipeline 10.

[0039] The speed-regulating peristaltic pump 7, the dilution solution 6, and the premixing tank 8 are connected through the second pipeline 11.

[0040] The speed-regulating peristaltic pump 7 pumps the interfering element solution 5 (auxiliary agent solution 12) and the dilution solution 6 into the premixing tank 8 for mixing and concentration adjustment, and the premixing tank 8 is connected to the three-way device 9.

[0041] The inner diameters of the pipelines connecting the three-way device 9 to the premixing tank 8 and the pipelines connecting the three-way device 9 to the test element solution 3 are the same.

[0042] The first peristaltic pump 1 simultaneously extracts the interfering element solution 5 (auxiliary agent solution 12), the test element solution 3, and the reducing agent 4 in the premixing tank 8 into the atomic fluorescence for analysis.

[0043] A method for on-line studying the interference and the effect of the auxiliary agent by atomic fluorescence, the concentration of the interfering element solution 5 (auxiliary agent solution 12) is formulated through the following formula;

[0044]

[0045] Note: C 0 is the original concentration of the interfering element solution 5 (auxiliary agent solution 12), with the unit of μg / mL;

[0046] C 1 is the concentration of the interfering element solution 5 (auxiliary agent solution 12) in the premixing tank 8

[0047] with the unit of μg / mL;

[0048] When sucking the interfering element solution 5 (auxiliary agent solution 12), the pump speed of the speed-regulating peristaltic pump 7 is a,

[0049] When sucking the dilution solution 6, the pump speed of the speed-regulating peristaltic pump 7 is c,

[0050] The inner diameter of the first pipeline 10 is d, and the inner diameter of the second pipeline 11 is b;

[0051] The working time of the speed-regulating peristaltic pump 7 for sucking the interfering element solution 5 (auxiliary agent solution 12) and the dilution solution 6 is the same;

[0052] When b, d, and the working time of the speed-regulating peristaltic pump 7 are fixed values; a and c can be adjusted to adjust the concentration of the interfering element solution 5 (auxiliary agent solution 12) in the premixing tank 8.

[0053] Working principle: By using different pump speeds of the speed-regulating peristaltic pump 7 and cooperating with the first pipe 10 and the second pipe 11 with different inner diameters, the pump speed, the inner diameter of the first pipe 10, and the inner diameter of the second pipe 11 can be changed within a unit time to suck different amounts of interfering element solution 5 (auxiliary agent solution 12) and diluent 6, and dilution can be achieved by mixing in the premixing tank 8. That is, it can be diluted to any concentration between zero and the original concentration of the interfering element. For example, if the prepared interfering element solution 5 (auxiliary agent solution 12) is 100 μg / mL, this online system for studying interference or auxiliary agents can study the interference conditions at each concentration point between 0 - 50 μg / mL (the concentration is diluted by half after passing through the tee device).

[0054] Example 2

[0055] According to the above design idea, the method steps for the online study of interference in the present invention are mainly as follows: Prepare an interfering element solution 5 (auxiliary agent solution 12) with a suitable concentration, connect the pipelines, turn on the atomic fluorescence spectrometer 2, and adjust it to the normal working state.

[0056] During the test,

[0057] Step 1: The speed-regulating peristaltic pump 7 works, and the speed-regulating peristaltic pump 7 sucks the interfering element solution 5 (auxiliary agent solution 12) through the first pipe 10 into the premixing tank 8.

[0058] Step 2: The speed-regulating peristaltic pump 7 works, and the speed-regulating peristaltic pump 7 sucks the dilution solution 6 through the second pipe 11. After mixing in the premixing tank 8, the atomic fluorescence spectrometer 2 starts to measure, and the fluorescence signal is measured according to the working steps of the instrument.

[0059] Repeat the above steps, change the pump speed of the speed-regulating peristaltic pump 7, suck different amounts of the interfering element solution 5 (auxiliary agent solution 12) and diluent 6 at different pump speeds, obtain interfering element solutions 5 (or auxiliary agent solutions 12) with different concentrations in the premixing tank 8, test the fluorescence intensity after mixing the interfering element solution 5 (or auxiliary agent solution 12) and the solution of the element to be measured 3, and judge the interference degree of the interfering element on the element to be measured and the effect of adding the auxiliary agent based on the change in fluorescence intensity.

[0060] The residual liquid after one measurement in the premixing tank 8 can be sucked clean as the instrument peristaltic pump rotates. Or a new premixing tank 8 can be replaced.

[0061] Example 3

[0062] Based on Example 1 and Example 2, experiments are conducted with arsenic element as an example.

[0063] Specific implementation steps:

[0064] Taking arsenic as an example, the same applies to other elements such as antimony, bismuth, mercury, selenium, lead, and cadmium. The concentrations of the elements to be measured and the interfering elements are selected according to the actual measurement requirements. The concentration of potassium borohydride-sodium hydroxide is selected after optimization. Interfering elements include major elements such as silicon, aluminum, iron, calcium, magnesium, titanium, manganese, etc., trace elements such as copper, lead, cobalt, nickel, zinc, etc., and the mutual interference of hydride elements themselves, etc.

[0065] Specific implementation steps for on-line research of interference:

[0066] Measurement preparation:

[0067] S1. Prepare a 20 μg / L arsenic standard solution (element to be measured) as required, a 20 g / L - 10 g / L potassium borohydride-sodium hydroxide mixed reaction solution, and prepare two cups of pure water as carrier solution (using water as carrier).

[0068] S2. Prepare interfering element solution 5 (auxiliary solution 12). Prepare 100 mL of 50 μg / mL copper solution (taking copper element as an example). Prepare dilution solution 6, which is deionized water with a certain acidity. The acidity of interfering element solution 5 (auxiliary solution 12), dilution solution 6, and element solution 3 to be measured is kept consistent.

[0069] S3. According to Figure 1 , install the three-way device 9, the premixing pool 8, and the speed-adjustable peristaltic pump 7. The first pipe 10 and the second pipe 11 of the speed-adjustable peristaltic pump 7 are made of silica capillary tubes with an inner diameter of 0.5 mm (pump tubes with different inner diameters can be used). The inner diameters of the pipe connecting the three-way device 9 to the premixing pool 8 and the pipe connecting the three-way device 9 to the element solution 3 to be measured are the same. Check that there is no air leakage or liquid leakage in the entire flow path.

[0070] S4. Turn on the atomic fluorescence spectrometer 2 for preheating, and adjust the instrument to the required working state according to the instrument instruction manual or the self-optimized parameters.

[0071] S5. Set the single-cycle working time of the speed-adjustable peristaltic pump 7 to 10 s. Ensure that in one measurement, the working time of the speed-adjustable peristaltic pump 7 for sucking interfering element solution 5 (auxiliary solution 12) and dilution solution 6 is the same. The pump speed of the speed-adjustable peristaltic pump 7 can be adjusted separately when sucking interfering element solution 5 (auxiliary solution 12) and dilution solution 6. That is, in the operation, the pump working time can be regarded as a constant, and the pump speed and the inner diameter of the pump tube are variables.

[0072] I. Measurement of the control blank point:

[0073] A1: Set the speed-adjustable peristaltic pump 7 to 100 r / min, insert the second pipe 12 into the dilution solution 6, turn on the pump to work, and the pump will automatically stop after the single working duration. At this time, the sucked dilution solution 6 flows into the premixing pool 8.

[0074] A2: The first peristaltic pump 1 rotates to suck the solution in the premixing tank 8, the arsenic standard solution of the element to be measured, and the potassium borohydride-sodium hydroxide mixed reaction solution.

[0075] A3: The instrument reads the measured fluorescence signal and records the fluorescence value.

[0076] A4: One measurement is completed. If multiple measurements are required, this step can be repeated to take the average value.

[0077] II. Measurement of the concentration point of interference element No. 1:

[0078] B1: Set the speed-adjustable peristaltic pump 7 to 100 r / min. Insert the first pipeline 10 into the 50 μg / mL interference element copper solution. Start the speed-adjustable peristaltic pump 7. After the single working duration, the pump stops automatically. At this time, the sucked interference element solution flows into the premixing tank 8.

[0079] B2: Insert the second pipeline 11 into the dilution solution 6. Set the speed-adjustable peristaltic pump 7 to 100 r / min. Start the pump. After the single working duration, the pump stops automatically. At this time, the sucked dilution solution 6 flows into the premixing tank 8.

[0080] B3: Mix the two solutions evenly through the premixing tank 8.

[0081] B4: The first peristaltic pump 1 rotates to suck the interference working solution in the premixing tank 8, the arsenic standard working solution of the element to be measured, and the potassium borohydride-sodium hydroxide mixed reaction solution.

[0082] B5: The instrument reads the measured fluorescence signal and records the fluorescence value.

[0083] B6: One measurement is completed. If multiple measurements are required, this step can be repeated to take the average value.

[0084] Under this step, the calculated concentration of the copper interference element in the premixing tank 8 after mixing is 25 μg / mL.

[0085] The inner diameters of the pipeline connecting the premixing tank 8 and the pipeline connecting the solution 3 of the element to be measured by the three-way device 9 are the same. Therefore, the calculated concentration of the copper interference element entering the atomic fluorescence spectrometer 2 through the three-way device 9 is 12.5 μg / mL.

[0086] III. Determination of the concentration of interference element No. 2:

[0087] C1: Set the speed-adjustable peristaltic pump 7 to 100 r / min. Insert the first pipeline 10 into the 50 μg / mL interference element copper solution. Start the speed-adjustable peristaltic pump 7. After the single working duration, the pump stops automatically. At this time, the sucked interference element solution 5 (auxiliary solution 12) flows into the premixing tank 8.

[0088] C2: Insert the second pipe 11 into the dilution solution 6, set the speed-regulating peristaltic pump 7 to 80 r / min, start the pump, and automatically stop the pump after the single working duration. At this time, the absorbed dilution solution 6 flows into the premixing tank 8.

[0089] C3: Mix the two solutions evenly through the premixing tank 8.

[0090] C4: The first peristaltic pump 1 rotates to absorb the interfering working solution in the premixing tank 8, absorb the standard working solution of the element arsenic to be measured, and absorb the potassium borohydride-sodium hydroxide mixed reaction solution.

[0091] C5: The instrument reads the measured fluorescence signal and records the fluorescence value.

[0092] C6: Complete 1 measurement. If multiple measurements are required and the average value is taken, this step can be repeated.

[0093] Under this step, the calculated concentration of the copper interference element in the premixing tank 8 after mixing is 27.8 μg / mL.

[0094] The inner diameters of the pipes connecting the premixing tank 8 by the tee device 9 and the pipes connecting the tee device 9 to the solution 3 of the element to be measured are the same. Therefore, the calculated concentration of the copper interference element entering the atomic fluorescence spectrometer 2 through the tee device 9 is 13.9 μg / mL.

[0095] The pump speeds of the peristaltic pumps for sucking the interfering element solution 5 (auxiliary solution 12) and the dilution solution 6 twice can be adjusted arbitrarily to achieve different concentrations.

[0096] The above measurements are set when the inner diameter of the pump tube is 0.5 mm.

[0097] The inner diameter of the pump tube can be selected as 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm... etc.

[0098] The concentration of the interfering element mixed solution in the premixing tank 8 can be calculated according to the following formula.

[0099] The specific calculation formula is:

[0100] The original concentration of the interfering element solution 5 (auxiliary solution 12) is C 0 , with the unit of μg / mL; the concentration of the interfering element solution 5 (auxiliary solution 12) in the premixing tank is C 1 , with the unit of μg / mL; the pump speed for sucking the interfering element solution 5 (auxiliary solution 12) is a, and the inner diameter of the pump tube is b; the pump speed for sucking the dilution solution 6 is c, and the inner diameter of the pump tube is d; (a, b, c, d have no unit, and only their ratios need to be calculated.)

[0101] Then

[0102]

[0103] (The pump working times of the interfering element absorbing solution 5 (auxiliary agent solution 12) and the dilution solution 6 are the same. For example, they are both set to 10 s, 20 s, etc., and the time is a fixed amount.)

[0104] The following points need to be explained:

[0105] 1. In the accompanying drawings of the embodiments of the present disclosure, only the structures related to the embodiments of the present disclosure are involved, and other structures can refer to the general design.

[0106] 2. Without conflict, the features in the same embodiment and different embodiments of the present disclosure can be combined with each other.

[0107] The above is only the specific implementation manner of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily think of changes or substitutions, which should all be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. An on-line method for studying interference and additives by atomic fluorescence, characterized in that, the concentration of the interference element solution or the additive solution is proportioned by the following formula; Note: C0 is the original concentration of the interference element solution or the additive solution, with the unit of μg / mL; C1 is the concentration of the interference element solution or the additive solution in the premixing pool, with the unit of μg / mL; when extracting the interference element solution or the additive solution, the pump speed of the speed-regulating peristaltic pump is a; when extracting the dilution solution, the pump speed of the speed-regulating peristaltic pump is c; the inner diameter of the first pipe is d, and the inner diameter of the second pipe is b; the working time of the speed-regulating peristaltic pump for extracting the interference element solution and the dilution solution is the same; or the working time of the speed-regulating peristaltic pump for extracting the additive solution and the dilution solution is the same; when b, d and the working time of the speed-regulating peristaltic pump are fixed values; a and c can be adjusted to adjust the concentration of the interference element solution or the additive solution in the premixing pool; wherein the method involves a system for on-line studying interference and additives by atomic fluorescence, the system includes an atomic fluorescence spectrometer, and the atomic fluorescence spectrometer is connected to a solution of an element to be measured and a reducing agent through a first peristaltic pump, and a solution concentration on-line preparation system is connected to the pipe where the solution of the element to be measured is connected to the first peristaltic pump through a tee device; the solution concentration on-line preparation system is used to on-line prepare interference element solutions and additive solutions with different concentrations for different solutions of elements to be measured; the solution concentration on-line preparation system includes a speed-regulating peristaltic pump and a premixing pool; the speed-regulating peristaltic pump, the interference element solution and the premixing pool are connected through a first pipe; the speed-regulating peristaltic pump, the dilution solution and the premixing pool are connected through a second pipe; the speed-regulating peristaltic pump pumps the interference element solution and the dilution solution into the premixing pool to mix and adjust the concentration, and the premixing pool is connected to the tee device; the solution concentration on-line preparation system includes a speed-regulating peristaltic pump and a premixing pool; the speed-regulating peristaltic pump, the additive solution and the premixing pool are connected through a first pipe; the speed-regulating peristaltic pump, the dilution solution and the premixing pool are connected through a second pipe; the speed-regulating peristaltic pump pumps the additive solution and the dilution solution into the premixing pool to mix and adjust the concentration, and the premixing pool is connected to the tee device.

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