Method and system for microfluidic detection of total phosphorus water quality by eliminating impurity interference

Abstract

The present application belongs to the technical field of total phosphorus determination in water quality testing, and specifically discloses a method and system for microfluidic detection of total phosphorus water quality by eliminating the interference of impurities. The method comprises: (1) calibrating with a standard solution to obtain a standard curve; (2) testing a water sample to be tested, including: testing a reference signal with pure water I 0; The water sample to be tested and the first oxidant are sequentially transmitted to the digestion colorimetric module to obtain a digestion signal I 水1 ; Determine whether to perform a second digestion, and if necessary, perform a second digestion; Use a reducing agent to test the digestion signal I 水2 ; Use colorimetric reagent to test digestion signal I 水3 ; Clean and digest the colorimetric module; Use pure water to test the reference signal I 水4 ; Calculate the water sample test results based on the test signal and the standard curve. The application adopts a secondary digestion method, which can not only effectively remove chromatic interference, but also effectively oxidize organic phosphorus compounds that are difficult to oxidize, thereby improving the accuracy of total phosphorus testing in water samples with more complex working conditions.

Description

Technical Field

[0001] The present application belongs to the technical field of total phosphorus determination in water quality testing, and specifically relates to a method and system for microfluidic detection of total phosphorus water quality by eliminating interference from impurities. Background Art

[0002] When testing the total phosphorus in water quality, some water samples are yellow or brown, especially when testing water samples during the flood season or when the working conditions are more complex. At this time, the water samples are not only interfered by turbidity but also have a large chromaticity value. In addition, some substances that produce chromaticity, such as organic matter in the water, have an impact on the total phosphorus reaction system. Therefore, when testing the total phosphorus content, the test results often have large errors, especially for small reaction systems. As we all know, turbidity can be removed by filtration, but chromaticity cannot be removed by filtration. Therefore, other methods must be relied on to eliminate the influence of chromaticity. Conventional total phosphorus testing uses potassium persulfate oxidation under neutral conditions. During the oxidation process, the solution will slowly become acidic. Under acidic conditions, the oxidation ability of potassium persulfate decreases, resulting in incomplete digestion of complex water samples. After the oxidation of water samples with higher chromaticity is completed, there is still chromaticity influence, so the test deviation is large. However, due to the material (PMMA, PDMS and other materials), the microfluidic chip cannot be digested at a higher temperature (generally <60°C). The insufficient digestion rate leads to large test deviations. In addition, colored substances, namely chromaticity, will be adsorbed on the microfluidic chip, and the light transmittance is seriously reduced. Currently, the instrument can increase the signal by adjusting the photocurrent, but the range of photocurrent improvement is limited and the increase in photocurrent will affect the service life of the light source. When increasing the photocurrent cannot meet the test conditions, the colorimetric module must be cleaned. However, the microfluidic chip has small channels and cannot be disassembled, so it is difficult to clean and can only be replaced, which further increases the operation and maintenance costs. Summary of the invention

[0003] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the purpose of the present application is to propose a method and system for microfluidic detection of total phosphorus water quality that eliminates impurity interference.

[0004] In one aspect of the present application, the present application proposes a method for microfluidic detection of total phosphorus water quality to eliminate impurity interference. According to an embodiment of the present application, the method comprises:

[0005] (1) Use standard solution for calibration to obtain a standard curve;

[0006] Step (1) includes:

[0007] (1-1) sequentially transmitting a preset volume of a first standard solution and a preset volume of a first oxidant to a digestion colorimetric module, so that the first oxidant digests the first standard solution to obtain a digestion signal I标1 ;

[0008] (1-2) delivering a preset volume of pure water to the digestion colorimetric module;

[0009] (1-3) Sending a preset volume of reducing agent to the digestion colorimetric module to obtain a digestion signal I 标2 ;

[0010] (1-4) The preset volume of the colorimetric reagent is transferred to the digestion colorimetric module to obtain a digestion signal. I 标3 ;

[0011] (1-5) Cleaning the digestion colorimetric module;

[0012] (1-6) Sending a preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 标4 ;

[0013] (1-7) According to the I 标1 , I 标2 , I 标3 and stated I 标4 The signal of the first standard solution is calculated;

[0014] (1-8) According to steps (1-1) to (1-7), calculate the absorbance of the second standard solution;

[0015] (1-9) fitting the standard curve according to the relationship between the concentration and absorbance of the first standard solution and the relationship between the concentration and absorbance of the second standard solution;

[0016] (2) Test the water sample to be tested, including:

[0017] (2-1) Sending a preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 0;

[0018] (2-2) sequentially transmitting a preset volume of the water sample to be tested and a preset volume of the first oxidant to the digestion colorimetric module, so that the first oxidant performs a first digestion on the water sample to be tested to obtain a digestion signal I 水1 ;

[0019] (2-3) When lg(I0 / I 水1 )>lg(I 标4 / I 标1)+b, delivering a preset volume of the second oxidant to the digestion colorimetric module so that the second oxidant performs a second digestion on the water sample to be tested, and the b value is 0.0005-0.008;

[0020] When lg(I0 / I 水1 )≤lg(I 标4 / I 标1 )+b, delivering a preset volume of pure water to the digestion colorimetric module;

[0021] (2-4) The preset volume of the reducing agent is transferred to the digestion colorimetric module to obtain a digestion signal. I 水2 ;

[0022] (2-5) The color developer of the preset volume is transferred to the digestion colorimetric module to obtain a digestion signal. I 水3 ;

[0023] (2-6) Cleaning the digestion colorimetric module;

[0024] (2-7) Sending a preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 水4 ;

[0025] (2-8) According to the I 水2 , I 水3 , I 水4 Calculate the absorbance of the water sample to be tested, and calculate the concentration of the water sample to be tested according to the absorbance of the water sample to be tested and the standard curve, wherein when When , the absorbance of the water sample to be tested is calculated using a compensated absorbance algorithm, and the c value is 0.0005~0.008; when When the absorbance of the water sample to be tested is calculated using an uncompensated absorbance algorithm.

[0026] According to the method for microfluidic detection of total phosphorus water quality to eliminate interference from impurities in the embodiment of the present application, a secondary digestion method is used, which can not only effectively remove chromatic interference, but also effectively oxidize organic phosphorus compounds that are difficult to oxidize, thereby improving the accuracy of total phosphorus testing in water samples with more complex working conditions. The method of the present application determines whether to turn on secondary digestion by itself, which can ensure the accuracy of the test while shortening the test time, making the instrument more intelligent. The compensation algorithm of the method of the present application can eliminate the influence of the complex water sample reaction process and the influence of light absorbing substances, which can further improve the accuracy.

[0027] In addition, the method according to the above embodiment of the present application may also have the following additional technical features:

[0028] In some embodiments of the present application, in step (1), at least two standard solutions are used for calibration, and the at least two standard solutions are potassium dihydrogen phosphate solutions of different concentrations.

[0029] In some embodiments of the present application, the first oxidant is a 25g / L~50g / L aqueous solution of potassium persulfate; and / or, the second oxidant is a 10g / L~20g / L aqueous solution of potassium permanganate; and / or, the reducing agent is a 30g / L~100g / L aqueous solution of ascorbic acid; and / or, the developer is an aqueous solution comprising potassium antimony tartrate, ammonium molybdate and sulfuric acid, the concentration of potassium antimony tartrate is 0.35g / L~0.7g / L, the concentration of ammonium molybdate is 13g / L~26g / L, and the concentration of sulfuric acid is 15wt%~40wt%.

[0030] In some embodiments of the present application, in step (1-1), a preset volume of the first oxidant is delivered to a digestion colorimetric module, heated to 110°C to 130°C, and digested for 1 min to 30 min to obtain a digestion signal. I 标1 .

[0031] In some embodiments of the present application, in step (1-3), a preset volume of the reducing agent is delivered to the digestion colorimetric module and reduced at 40°C to 50°C for 30s to 10min to obtain a digestion signal. I 标2 ; and / or, in step (1-4), the color developer of a preset volume is transferred to the digestion colorimetric module, and the color is developed at 40°C to 50°C for 30s to 10min to obtain a digestion signal I 标3 .

[0032] In some embodiments of the present application, in step (2-2), a preset volume of the first oxidant is transferred to a digestion colorimetric module, heated to 110°C to 130°C, and digested for 1 min to 30 min to obtain a digestion signal. I 水1 ; and / or, in step (2-3), a preset volume of the second oxidant is transferred to the digestion colorimetric module, heated to 60°C~105°C, and digested for 1min~10min.

[0033] In some embodiments of the present application, in step (2-4), a preset volume of the reducing agent is delivered to the digestion colorimetric module and reduced at 40°C to 50°C for 30s to 10min to obtain a digestion signal. I 水2; and / or, in step (2-5), the color developer of a preset volume is transferred to the digestion colorimetric module, and the color is developed at 40°C to 50°C for 30s to 10min to obtain a digestion signal I 水3 .

[0034] In some embodiments of the present application, in step (2-8), the compensated absorbance algorithm is: ; The uncompensated absorbance algorithm: Among them, A 水样 is the absorbance of the water sample to be tested, V1 represents the volume of the water sample to be tested; V2 represents the volume of the first oxidant; V3 represents the volume of the second oxidant or the pure water in step (2-3); V4 represents the volume of the reducing agent; and V5 represents the volume of the developer.

[0035] In a second aspect of the present application, the present application proposes a system for implementing the method described in the above embodiment. According to an embodiment of the present application, the system includes:

[0036] A microfluidic chip, wherein a metering module and a flow channel are provided on the microfluidic chip, and a plurality of valves are provided on the flow channel, and the inlet and flow direction of the water sample to be tested, pure water, standard solution, first oxidant, second oxidant, reducing agent and developer are controlled by controlling the valves on the flow channel;

[0037] A digestion and colorimetric module, wherein the digestion and colorimetric module is connected to the metering module;

[0038] A three-way valve, the three-way valve is arranged between the digestion colorimetric module and the metering module;

[0039] a first peristaltic pump, wherein the first peristaltic pump is connected to the metering module;

[0040] A second peristaltic pump, wherein the second peristaltic pump is connected to the digestion and colorimetric module.

[0041] According to the system of the embodiment of the present application, by separating the digestion colorimetric module from the microfluidic chip (i.e., not setting the digestion colorimetric module on the microfluidic chip), and placing the digestion colorimetric module on the outer end of the microfluidic chip, the temperature of the first oxidation and the second oxidation occurring on the digestion colorimetric module can be increased, thereby effectively improving the efficiency and effect of oxidative digestion. As a result, the system of the present application can test water samples with more complex working conditions, not only effectively removing chromatic interference, but also improving the digestion efficiency of total phosphorus, ensuring the accuracy and stability of total phosphorus testing.

[0042] In addition, the system according to the above embodiment of the present application may also have the following additional technical features:

[0043] In some embodiments of the present application, the system also includes: a water sample supply unit to be tested, a first valve and a fifth valve are arranged between the water sample supply unit to be tested and the metering module; a pure water supply unit, a second valve, a fourth valve and the fifth valve are arranged between the pure water supply unit and the metering module; a standard solution supply unit, a third valve and the fifth valve are arranged between the standard solution supply unit and the metering module; a reducing agent supply unit, a sixth valve is arranged between the reducing agent supply unit and the metering module; a color developer supply unit, a seventh valve is arranged between the color developer supply unit and the metering module; a first oxidant supply unit, a tenth valve is arranged between the first oxidant supply unit and the metering module; a second oxidant supply unit, an eighth valve is arranged between the second oxidant supply unit and the metering module; and a ninth valve is also arranged between the metering module and the air end.

[0044] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0046] Figure 1 This is a flow chart of step S100 of the present application;

[0047] Figure 2 This is a flow chart of step S200 of the present application;

[0048] Figure 3 A schematic diagram of the system structure of the method for microfluidic detection of total phosphorus water quality for eliminating impurity interference in the implementation of the present application.

[0049] Reference numerals:

[0050] 1-digestion colorimetric module, 100-microfluidic chip, 2-metering module, 3-first valve, 4-second valve, 5-third valve, 6-fourth valve, 7-fifth valve, 8-sixth valve, 9-seventh valve, 10-eighth valve, 11-tenth valve, 12-ninth valve, 13-test water sample supply unit, 14-pure water supply unit, 15-standard solution supply unit, 16-reducing agent supply unit, 17-developing agent supply unit, 18-second oxidant supply unit, 19-first oxidant supply unit, 20-first peristaltic pump, 21-air end, 22-second peristaltic pump, 23-waste liquid collection unit, 24-three-way valve. DETAILED DESCRIPTION

[0051] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0052] In one aspect of the present application, the present application proposes a method for microfluidic detection of total phosphorus water quality to eliminate impurity interference. Figure 1 and attached Figure 2 The method comprises: S100: calibrating with a standard solution to obtain a standard curve; step S100 comprises: S110: sequentially transmitting a preset volume of a standard solution and a preset volume of a first oxidant to a digestion colorimetric module, so that the first oxidant digests the standard solution to obtain a digestion signal I 标1 ; S120: Send a preset volume of pure water to the digestion colorimetric module; S130: Send a preset volume of reducing agent to the digestion colorimetric module to obtain a digestion signal I 标2 ; S140: Send the preset volume of color developer to the digestion colorimetric module to obtain a digestion signal I 标3 ; S150: Clean the digestion colorimetric module; S160: Send a preset volume of pure water to the digestion colorimetric module to obtain a reference signal ; S170: According to I 标3 and I 标4 signal, calculate the absorbance of the first standard solution; S180: calculate the absorbance of the second standard solution according to steps S110 to S170; S190: obtain a standard curve by fitting according to the relationship between the concentration and absorbance of the first standard solution and the relationship between the concentration and absorbance of the second standard solution; S200: test the water sample to be tested, including: S210: transfer a preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 0; S220: sequentially transmitting a preset volume of the water sample to be tested and a preset volume of the first oxidant to the digestion colorimetric module, so that the first oxidant performs a first digestion on the water sample to be tested to obtain a digestion signal I 水1 ; S230: When When lg(I0 / I 水1 )≤lg(I 标4 / I 标1)+b, a preset volume of pure water is transmitted to the digestion colorimetric module; S240: a preset volume of reducing agent is transmitted to the digestion colorimetric module to obtain a digestion signal ; S250: Send the preset volume of color developer to the digestion colorimetric module to obtain a digestion signal I 水3 ; S260: Clean the digestion colorimetric module; S270: Send a preset volume of pure water to the digestion colorimetric module to obtain a reference signal ; S280: According to I 水2 , I 水3 , I 水4 Calculate the absorbance of the water sample to be tested, and calculate the concentration of the water sample to be tested according to the absorbance of the water sample to be tested and the standard curve. When , the absorbance of the water sample to be tested is calculated using the compensated absorbance algorithm, and the c value is 0.0005~0.008; when When the absorbance of the water sample is calculated, the absorbance algorithm without compensation is used.

[0053] The following is a detailed description of the method for microfluidic detection of total phosphorus water quality proposed in this application to eliminate impurity interference:

[0054] Specifically, the above-mentioned method for microfluidic detection of total phosphorus water quality by eliminating impurity interference includes the following steps:

[0055] S100: Calibrate with a standard solution to obtain a standard curve;

[0056] In this step, at least two standard solutions can be used to calibrate the instrument. At least two standard solutions are total phosphorus standard solutions prepared with potassium dihydrogen phosphate, for example, a total phosphorus standard solution with a concentration of 0 mg / L, a total phosphorus standard solution with a concentration of 0.2 mg / L, or a total phosphorus standard solution with a concentration of 0.8 mg / L.

[0057] Specifically, refer to the attached Figure 1 , step S100 includes the following steps:

[0058] S110: sequentially transmitting a preset volume of the first standard solution and a preset volume of the first oxidant to the digestion colorimetric module, so that the first oxidant digests the first standard solution to obtain a digestion signal I 标1 ;

[0059] In this step, refer to the attached Figure 3, take the first standard solution: after emptying the digestion colorimetric module 1 and the metering module 2, open the third valve 5 and the fifth valve 7, switch the three-way valve 24 to the second peristaltic pump 22 end, rotate the second peristaltic pump 22 forward, and the first standard solution is discharged to the waste liquid collection unit 23 through the third valve 5, the fifth valve 7, the three-way valve 24, and the second peristaltic pump 22; close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, and the first standard solution is metered to the metering module 2 through the third valve 5 and the fifth valve 7, close the first peristaltic pump 20, close the third valve 5 and the fifth valve 7, open the ninth valve 12, rotate the second peristaltic pump 22 forward, discharge the residual liquid in the pipeline to the waste liquid collection unit 23, and close the second peristaltic pump 22; switch the three-way valve 24 to the digestion colorimetric module 1 end, reverse the first peristaltic pump 20, transfer the standard solution to the digestion colorimetric module 1, close the first peristaltic pump 20, and switch the three-way valve 24 to the second peristaltic pump 22 end.

[0060] In this step, refer to the attached Figure 3 , take the first oxidant: open the tenth valve 11, rotate the second peristaltic pump 22 forward, the first oxidant is discharged to the waste liquid collection unit 23 through the tenth valve 11, the three-way valve 24, and the second peristaltic pump 22; close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, the first oxidant is metered to the metering module 2 through the tenth valve 11, close the first peristaltic pump 20, close the tenth valve 11, open the ninth valve 12, rotate the second peristaltic pump 22 forward, discharge the residual liquid in the pipeline to the waste liquid collection unit 23, and close the second peristaltic pump 22; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the first oxidant to the digestion colorimetric module 1, close the first peristaltic pump 20, switch the three-way valve 24 to the end of the second peristaltic pump 22, heat and digest, and test the digestion signal at this time I 标1 , cool down to a certain temperature (for example, 60°C).

[0061] According to some specific embodiments of the present application, in step S110, a preset volume of the first oxidant is delivered to the digestion colorimetric module 1, heated to 110°C to 130°C (as an example, it can be 110°C, 115°C, 120°C, 125°C, 130°C, etc.), and digested for 1min to 30min (as an example, it can be 1min, 4min, 5min, 10min, 15min, 20min, 25min, 30min, etc.), and a digestion signal is obtained. I 标1 As a preferred embodiment, a preset volume of the first oxidant is delivered to the digestion colorimetric module 1, heated to 120°C, digested for 4 minutes, and a digestion signal is obtained. I 标1 .

[0062] S120: delivering a preset volume of pure water to a digestion and colorimetric module;

[0063] In this step, refer to the attached Figure 3 , take pure water: open the second valve 4 and the fifth valve 7, switch the three-way valve 24 to the second peristaltic pump 22 end, rotate the second peristaltic pump 22 forward, and the pure water is discharged to the waste liquid collection unit 23 through the second valve 4, the fifth valve 7, the three-way valve 24, and the second peristaltic pump 22, close the second peristaltic pump 22, and rotate the first peristaltic pump 20 forward. The pure water passes through the second valve 4 and the fifth valve 7 to the metering module 2 for metering, close the first peristaltic pump 20, close the second valve 4 and the fifth valve 7, open the ninth valve 12, and rotate the second peristaltic pump 22 forward to discharge the residual liquid in the pipeline to the waste liquid collection unit 23; close the second peristaltic pump 22; switch the three-way valve 24 to the digestion colorimetric module 1 end, reverse the first peristaltic pump 20, transfer the pure water to the digestion colorimetric module 1, close the first peristaltic pump 20, and switch the three-way valve 24 to the second peristaltic pump 22 end.

[0064] S130: Send the preset volume of reducing agent to the digestion colorimetric module to obtain a digestion signal I 标2 ;

[0065] In this step, refer to the attached Figure 3 , take the reducing agent: open the sixth valve 8, switch the three-way valve 24 to the end of the second peristaltic pump 22, rotate the second peristaltic pump 22 forward, the reducing agent is discharged to the waste liquid collection unit 23 through the sixth valve 8, the three-way valve 24, and the second peristaltic pump 22, close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, the reducing agent is metered to the metering module 2 through the sixth valve 8, close the first peristaltic pump 20, close the sixth valve 8, open the ninth valve 12, rotate the second peristaltic pump 22 forward, and discharge the residual liquid in the pipeline to the waste liquid collection unit 23; close the second peristaltic pump 22; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the reducing agent to the digestion colorimetric module 1, close the first peristaltic pump 20, switch the three-way valve 24 to the end of the second peristaltic pump 22, and test the digestion signal at this time I 标2 .

[0066] According to some further specific embodiments of the present application, in step S130, a preset volume of reducing agent is delivered to the digestion colorimetric module 1, and reduced at 40°C to 50°C (as an example, it can be 40°C, 42°C, 45°C, 47°C, 50°C, etc.) for 30s to 10min (as an example, it can be 30s, 1min, 2min, 4min, 6min, 8min, 10min, etc.), and a digestion signal is obtained. I 标2 .

[0067] S140: Send the preset volume of color developer to the digestion colorimetric module to obtain a digestion signal I 标3 ;

[0068] In this step, refer to the attached Figure 3 , take the color developer: open the seventh valve 9, switch the three-way valve 24 to the second peristaltic pump 22 end, rotate the second peristaltic pump 22 forward, the color developer is discharged to the waste liquid collection unit 23 through the seventh valve 9, the three-way valve 24, and the second peristaltic pump 22, close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, the color developer is metered to the metering module 2 through the seventh valve 9, close the first peristaltic pump 20, close the seventh valve 9, open the ninth valve 12, rotate the second peristaltic pump 22 forward, and discharge the residual liquid in the pipeline to the waste liquid collection unit 23; close the second peristaltic pump 22; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the color developer to the digestion colorimetric module 1, close the first peristaltic pump 20, switch the three-way valve 24 to the end of the second peristaltic pump 22, and test the digestion signal at this time after color development for 30s~10min I 标3 .

[0069] According to some further specific embodiments of the present application, in step S140, a preset volume of color developer is transferred to the digestion colorimetric module 1, and the color is developed at 40°C to 50°C (as an example, it can be 40°C, 42°C, 45°C, 47°C, 50°C, etc.) for 30s to 10min (as an example, it can be 30s, 1min, 2min, 4min, 6min, 8min, 10min, etc.), and a digestion signal is obtained. I 标3 .

[0070] S150: cleaning and digestion colorimetric module;

[0071] In this step, refer to the attached Figure 3 , clean metering module 2 and digestion colorimetric module 1: switch the three-way valve 24 to the end of the digestion colorimetric module 1, rotate the first peristaltic pump 20 forward, transfer the solution in the digestion colorimetric module 1 to the metering module 2, switch the three-way valve 24 to the end of the second peristaltic pump 22, rotate the second peristaltic pump 22 forward, reverse the first peristaltic pump 20, discharge the waste liquid to the waste liquid collection unit 23, turn off the first peristaltic pump 20, turn off the second peristaltic pump 22; open the second valve 4 and the fourth valve 6, rotate the first peristaltic pump 20 forward, and the pure water passes through the second valve 4 and the fourth valve 6. Go to the metering module 2, close the first peristaltic pump 20, close the second valve 4 and the fourth valve 6, switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the pure water to the digestion colorimetric module 1, rotate the first peristaltic pump 20 forward, transfer the cleaned pure water to the metering module 2, switch the three-way valve 24 to the end of the second peristaltic pump 22, rotate the second peristaltic pump 22 forward, reverse the first peristaltic pump 20, discharge the waste liquid to the waste liquid collection unit 23, close the first peristaltic pump 20, close the second peristaltic pump 22, and repeat once.

[0072] S160: Send the preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 标4 ;

[0073] In this step, the reference signal is tested: the second valve 4 and the fourth valve 6 are opened, the second peristaltic pump 22 is closed, the first peristaltic pump 20 is rotated forward, and the pure water flows through the second valve 4 and the fourth valve 6 to the metering module 2, the first peristaltic pump 20 is closed, and the second valve 4 and the fourth valve 6 are closed; the three-way valve 24 is switched to the end of the digestion colorimetric module 1, the first peristaltic pump 20 is reversed, and the pure water is transferred to the digestion colorimetric module 1, and the signal at this time is tested. I 标4 .

[0074] S170: According to I 标3 and I 标4 The signal is used to calculate the absorbance A1 of the first standard solution;

[0075] In this step, A1= I 标4 / I 标3 .

[0076] S180: According to steps S110 to S170, the absorbance A2 of the second standard solution is calculated;

[0077] In this step, the absorbance A2 of the second standard solution is calculated in the same manner as in steps S110 to S170.

[0078] S190: fitting a standard curve according to the relationship between the concentration and the absorbance of the first standard solution and the relationship between the concentration and the absorbance of the second standard solution.

[0079] In the embodiment of the present application, at least two standard solutions are used for calibration, and at least two standard solutions are potassium dihydrogen phosphate solutions of different concentrations. That is, the second standard solution or the third standard solution is tested in the same manner, and a standard curve is calculated based on the test signal.

[0080] In the embodiments of the present application, the above standard curve refers to a curve obtained by fitting the relationship between the concentration and absorbance of the standard solution. The concentration of the standard solution is proportional to the absorbance. , k is the slope of the standard curve obtained by fitting, x is a coefficient, and the absorbance A1 of the first standard solution and its corresponding concentration, and the absorbance A2 of the second standard solution and its corresponding concentration are substituted into the formula of the standard curve to obtain the k value and x value. I 水2 , I水3 , I 水4 Calculate the absorbance A of the water sample to be tested 水样 , by substituting it into the standard curve formula, the concentration of the water sample to be tested can be calculated.

[0081] According to some specific embodiments of the present application, the first oxidant is 25g / L~50g / L of potassium persulfate aqueous solution; and / or, the reducing agent is 30g / L~100g / L of ascorbic acid aqueous solution; and / or, the developer is an aqueous solution including potassium antimony tartrate, ammonium molybdate and sulfuric acid, the concentration of potassium antimony tartrate is 0.35g / L~0.7g / L, the concentration of ammonium molybdate is 13g / L~26g / L, and the concentration of sulfuric acid is 15wt%~40wt%.

[0082] S200: Test the water sample to be tested;

[0083] Specifically, refer to the attached Figure 2 , step S200 includes:

[0084] S210: Send the preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 0;

[0085] In this step, refer to the attached Figure 3 , test the reference signal: after draining the digestion colorimetric module 1 and the metering module 2, open the second valve 4 and the fifth valve 7, close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, and the pure water flows through the second valve 4 and the fifth valve 7 to the metering module 2. Close the first peristaltic pump 20, close the second valve 4 and the fifth valve 7; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, and transfer the pure water to the digestion colorimetric module 1. Test the signal at this time I 0.

[0086] S220: sequentially transmitting a preset volume of the water sample to be tested and a preset volume of the first oxidant to the digestion colorimetric module, so that the first oxidant performs a first digestion on the water sample to be tested to obtain a digestion signal I 水1 ;

[0087] In this step, refer to the attached Figure 3, take the water sample to be tested: after emptying the digestion colorimetric module 1 and the metering module 2, open the first valve 3 and the fifth valve 7, switch the three-way valve 24 to the second peristaltic pump 22 end, rotate the second peristaltic pump 22 forward, and the water sample is discharged to the waste liquid collection unit 23 through the first valve 3, the fifth valve 7, the three-way valve 24, and the second peristaltic pump 22; close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, and the water sample is metered through the first valve 3 and the fifth valve 7 to the metering module 2, close the first peristaltic pump 20, close the first valve 3 and the fifth valve 7, open the ninth valve 12, rotate the second peristaltic pump 22 forward, discharge the residual liquid in the pipeline to the waste liquid collection unit 23, and close the second peristaltic pump 22; switch the three-way valve 24 to the digestion colorimetric module 1 end, reverse the first peristaltic pump 20, transfer the water sample to the digestion colorimetric module 1, close the first peristaltic pump 20, and switch the three-way valve 24 to the second peristaltic pump 22 end.

[0088] In this step, refer to the attached Figure 3 , take the first oxidant: open the tenth valve 11, rotate the second peristaltic pump 22 forward, the first oxidant is discharged to the waste liquid collection unit 23 through the tenth valve 11, the three-way valve 24, and the second peristaltic pump 22; close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, the first oxidant is metered to the metering module 2 through the tenth valve 11, close the first peristaltic pump 20, close the tenth valve 11, open the ninth valve 12, rotate the second peristaltic pump 22 forward, discharge the residual liquid in the pipeline to the waste liquid collection unit 23, and close the second peristaltic pump 22; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the first oxidant to the digestion colorimetric module 1, close the first peristaltic pump 20, switch the three-way valve 24 to the end of the second peristaltic pump 22, heat and digest, and oxidize all the phosphorus in the water sample into orthophosphate, and test the digestion signal at this time I 水1 , cool down to a certain temperature (for example, 60°C), and determine whether to perform secondary digestion based on the signal: if secondary digestion is required, enter process 4a; if secondary digestion is not required, enter process 4b.

[0089] According to some specific embodiments of the present application, in step S220, a preset volume of the first oxidant is delivered to the digestion colorimetric module 1, heated to 110°C to 130°C (as an example, it can be 110°C, 115°C, 120°C, 125°C, 130°C, etc.), and digested for 1min to 30min (as an example, it can be 1min, 4min, 5min, 10min, 15min, 20min, 25min, 30min, etc.), and a digestion signal is obtained. I 水1 As a preferred embodiment, a preset volume of the first oxidant is delivered to the digestion colorimetric module 1, heated to 120°C, digested for 4 minutes, and a digestion signal is obtained. I 水1 .

[0090] S230: Determine whether to use a second oxidant to perform a second digestion on the water sample to be tested;

[0091] In this step, when When the preset volume of the second oxidant is delivered to the digestion colorimetric module 1, the second oxidant is used to digest the water sample for the second time (i.e., process 4a). When the preset volume of pure water is transferred to the digestion colorimetric module 1 (i.e., process 4b), the b value is in the range of 0.0005~0.008, which can be determined according to the actual test situation, based on the slope k of the standard curve calibrated above and the absolute value of the relative error Re of the standard solution test [Re=(average value of the standard solution test-standard solution concentration value) / standard solution concentration value], and the requirement is .

[0092] As mentioned above, the above standard curve refers to the curve obtained by fitting the relationship between the concentration and absorbance of the standard solution. The concentration of the standard solution is proportional to the absorbance. , k is the slope of the fitted standard curve, x is a coefficient, and the absorbance A1 of the first standard solution and its corresponding concentration, and the absorbance A2 of the second standard solution and its corresponding concentration are substituted into the formula of the standard curve to obtain the k value and x value.

[0093] Specifically, (4a process) take the second oxidant: open the eighth valve 10, switch the three-way valve 24 to the second peristaltic pump 22 end, rotate the second peristaltic pump 22 forward, and the pure water is discharged to the waste liquid collection unit 23 through the eighth valve 10, the three-way valve 24, and the second peristaltic pump 22. Turn off the second peristaltic pump 22, and rotate the first peristaltic pump 20 forward. The second oxidant is metered to the metering module 2 through the eighth valve 10, and the first peristaltic pump 20 is turned off. The eighth valve 10 is closed and the ninth valve 12 is opened. Rotate the second peristaltic pump 22 forward to discharge the residual liquid in the pipeline to the waste liquid collection unit 23; turn off the second peristaltic pump 22; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the second oxidant to the digestion colorimetric module 1, turn off the first peristaltic pump 20, and switch the three-way valve 24 to the end of the second peristaltic pump 22; heat and digest to oxidize and digest the difficult-to-digest colored substances in step S220, and cool down to a certain temperature (for example, 60°C).

[0094] (4b process) Take pure water: open the second valve 4 and the fifth valve 7, switch the three-way valve 24 to the second peristaltic pump 22 end, rotate the second peristaltic pump 22 forward, and the pure water is discharged to the waste liquid collection unit 23 through the second valve 4, the fifth valve 7, the three-way valve 24, and the second peristaltic pump 22. Close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, and the pure water is metered to the metering module 2 through the second valve 4 and the fifth valve 7. Close the first peristaltic pump 20, close the second valve 4 and the fifth valve 7, open the ninth valve 12, and rotate the second peristaltic pump 22 forward to discharge the residual liquid in the pipeline to the waste liquid collection unit 23; close the second peristaltic pump 22; switch the three-way valve 24 to the digestion colorimetric module 1 end, reverse the first peristaltic pump 20, and transfer the pure water to the digestion colorimetric module 1. Close the first peristaltic pump 20 and switch the three-way valve 24 to the second peristaltic pump 22 end.

[0095] According to some specific embodiments of the present application, in step S230, a preset volume of the second oxidant is delivered to the digestion colorimetric module 1, heated to 60°C to 105°C (as an example, it can be 60°C, 70°C, 80°C, 90°C, 100°C, 105°C, etc.), and digested for 1min to 10min (as an example, it can be 1min, 2min, 4min, 6min, 8min, 10min, etc.). As a preferred embodiment, a preset volume of the second oxidant is delivered to the digestion colorimetric module 1, heated to 95°C and digested for 5min.

[0096] According to some further specific embodiments of the present application, the first oxidant is 25 g / L~50 g / L of potassium persulfate aqueous solution; and / or, the second oxidant is 10 g / L~20 g / L of potassium permanganate aqueous solution; and / or, the reducing agent is 30 g / L~100 g / L of ascorbic acid aqueous solution; and / or, the developer is an aqueous solution including potassium antimony tartrate, ammonium molybdate and sulfuric acid, the concentration of potassium antimony tartrate is 0.35 g / L~0.7 g / L, the concentration of ammonium molybdate is 13 g / L~26 g / L, and the concentration of sulfuric acid is 15 wt%~40 wt%.

[0097] It should be noted that the second oxidant can also be acidic potassium permanganate, and what is added is acidic water without the need for secondary digestion. The amount of acid in acidic potassium permanganate and pure water is the same.

[0098] S240: Send the preset volume of reducing agent to the digestion colorimetric module to obtain a digestion signal I 水2 ;

[0099] In this step, refer to the attached Figure 3, take the reducing agent: open the sixth valve 8, switch the three-way valve 24 to the end of the second peristaltic pump 22, rotate the second peristaltic pump 22 forward, the reducing agent is discharged to the waste liquid collection unit 23 through the sixth valve 8, the three-way valve 24, and the second peristaltic pump 22, close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, the reducing agent is metered to the metering module 2 through the sixth valve 8, close the first peristaltic pump 20, close the sixth valve 8, open the ninth valve 12, rotate the second peristaltic pump 22 forward, and discharge the residual liquid in the pipeline to the waste liquid collection unit 23; close the second peristaltic pump 22; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the reducing agent to the digestion colorimetric module 1, close the first peristaltic pump 20, switch the three-way valve 24 to the end of the second peristaltic pump 22, and test the digestion signal at this time I 水2 .

[0100] According to some further specific embodiments of the present application, a preset volume of reducing agent is delivered to the digestion colorimetric module 1, and reduced at 40°C to 50°C (as an example, it can be 40°C, 42°C, 45°C, 47°C, 50°C, etc.) for 30s to 10min (as an example, it can be 30s, 1min, 2min, 4min, 6min, 8min, 10min, etc.), and a digestion signal is obtained. I 水2 .

[0101] S250: Send the preset volume of color developer to the digestion colorimetric module to obtain a digestion signal I 水3 ;

[0102] In this step, refer to the attached Figure 3 , take the color developer: open the seventh valve 9, switch the three-way valve 24 to the end of the second peristaltic pump 22, rotate the second peristaltic pump 22 forward, the color developer is discharged to the waste liquid collection unit 23 through the seventh valve 9, the three-way valve 24, and the second peristaltic pump 22, close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, the color developer is metered to the metering module 2 through the seventh valve 9, close the first peristaltic pump 20, close the seventh valve 9, open the ninth valve 12, rotate the second peristaltic pump 22 forward, and discharge the residual liquid in the pipeline to the waste liquid collection unit 23; close the second peristaltic pump 22; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the color developer to the digestion colorimetric module 1, close the first peristaltic pump 20, switch the three-way valve 24 to the end of the second peristaltic pump 22, and test the digestion signal at this time after color development. I 水3 .

[0103] According to some further specific embodiments of the present application, in step S250, a preset volume of color developer is transferred to the digestion colorimetric module 1, and the color is developed at 40°C to 50°C (as an example, it can be 40°C, 42°C, 45°C, 47°C, 50°C, etc.) for 30s to 10min (as an example, it can be 30s, 1min, 2min, 4min, 6min, 8min, 10min, etc.), and a digestion signal is obtained. I 水3 .

[0104] S260: cleaning and digestion colorimetric module;

[0105] In this step, refer to the attached Figure 3 , clean metering module 2 and digestion colorimetric module 1: switch the three-way valve 24 to the end of the digestion colorimetric module 1, rotate the first peristaltic pump 20 forward, transfer the solution in the digestion colorimetric module 1 to the metering module 2, switch the three-way valve 24 to the end of the second peristaltic pump 22, rotate the second peristaltic pump 22 forward, reverse the first peristaltic pump 20, discharge the waste liquid to the waste liquid collection unit 23, turn off the first peristaltic pump 20, turn off the second peristaltic pump 22; open the second valve 4 and the fourth valve 6, rotate the first peristaltic pump 20 forward, and the pure water passes through the second valve 4 and the fourth valve 6. Go to the metering module 2, close the first peristaltic pump 20, close the second valve 4 and the fourth valve 6, switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the pure water to the digestion colorimetric module 1, rotate the first peristaltic pump 20 forward, transfer the cleaned pure water to the metering module 2, switch the three-way valve 24 to the end of the second peristaltic pump 22, rotate the second peristaltic pump 22 forward, reverse the first peristaltic pump 20, discharge the waste liquid to the waste liquid collection unit 23, close the first peristaltic pump 20, close the second peristaltic pump 22, and repeat once.

[0106] S270: Send the preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 水4 ;

[0107] In this step, refer to the attached Figure 3 , test reference signal: open the second valve 4 and the fourth valve 6, close the second peristaltic pump 22, rotate the first peristaltic pump 20 forward, pure water passes through the second valve 4 and the fourth valve 6 to the metering module 2, close the first peristaltic pump 20, close the second valve 4 and the fourth valve 6; switch the three-way valve 24 to the end of the digestion colorimetric module 1, reverse the first peristaltic pump 20, transfer the pure water to the digestion colorimetric module 1, and test the signal at this time I 水4 .

[0108] S280: According to I 水2 , I 水3 , I 水4Calculate the absorbance of the water sample to be tested, and calculate the concentration of the water sample to be tested based on the absorbance of the water sample to be tested and the standard curve.

[0109] In this step, when When , the absorbance of the water sample to be tested is calculated using the compensated absorbance algorithm, and the c value is 0.0005~0.008; when When the absorbance of the water sample is calculated, the absorbance algorithm without compensation is used.

[0110] Specifically, when When , it means that there is turbidity interference after adding the reagent and the interference is large, exceeding the indication error range. The absorbance of the water sample to be tested needs to be compensated by the absorbance algorithm to deduct the interference; when When the value is 0.0005~0.008, it means that there is little turbidity interference or no interference after adding the reducing agent reagent. Within the indication error range, the test requirements can be met without compensation. The absorbance of the water sample to be tested is determined by the uncompensated absorbance algorithm. The c value is between 0.0005 and 0.008, which can be determined according to the actual test situation, based on the slope k of the above-calibrated standard curve and the absolute value of the relative error Re of the standard solution test [Re= (average value of the standard solution test-standard solution concentration value) / standard solution concentration value], and the requirements are .

[0111] In the embodiments of the present application, according to I 水2 , I 水3 , I 水4 Calculate the absorbance of the water sample to be tested and compensated absorbance algorithm:

[0112]

[0113] Uncompensated absorbance algorithm:

[0114] A 水样 =lg( I 水4 / I 水3 )

[0115] Among them, A 水样 is the absorbance of the water sample to be tested, V1 represents the volume of the water sample to be tested; V2 represents the volume of the first oxidant; V3 represents the volume of the second oxidant (or pure water in step S230); V4 represents the volume of the reducing agent; and V5 represents the volume of the developer.

[0116] In the embodiments of the present application, the above standard curve refers to a curve obtained by fitting the relationship between the concentration and absorbance of the standard solution. The concentration of the standard solution is proportional to the absorbance. , k is the slope of the standard curve obtained by fitting, x is a coefficient, and the absorbance A1 of the first standard solution and its corresponding concentration, and the absorbance A2 of the second standard solution and its corresponding concentration are substituted into the formula of the standard curve to obtain the k value and x value. I 水2 , I 水3 , I 水4 Calculate the absorbance A of the water sample to be tested 水样 , by substituting it into the standard curve formula, the concentration of the water sample to be tested can be calculated.

[0117] The method for microfluidic detection of total phosphorus water quality according to the embodiment of the present application to eliminate impurity interference has at least the following advantages:

[0118] 1. The method of this application adopts a secondary digestion method, that is, potassium persulfate is used to complete the first oxidation, and then potassium permanganate is added for the second oxidation to eliminate the interference of color. This method can not only effectively remove the interference of color, but also effectively oxidize the organophosphorus compounds that are difficult to oxidize, and improve the accuracy of total phosphorus testing in water samples with more complex working conditions.

[0119] It should be noted that during the first oxidation process using potassium persulfate, the solution will slowly become acidic. Under acidic conditions, the oxidation capacity of potassium persulfate is reduced, resulting in incomplete digestion of complex water samples, and the chromaticity of water samples with higher chromaticity is still affected after oxidation, so the test deviation is large. In view of this, the present application uses potassium permanganate for the second oxidation, which can effectively eliminate substances that produce chromaticity and organophosphorus compounds that are difficult to oxidize under acidic conditions.

[0120] 2. The method of the present application separates the digestion colorimetric module 1 from the microfluidic chip 100 (i.e., the digestion colorimetric module 1 is not set on the microfluidic chip 100), and places the digestion colorimetric module 1 at the outer end of the microfluidic chip 100, which can increase the temperature of the first oxidation and the second oxidation occurring on the digestion colorimetric module 1. The temperature of the first oxidation can be increased to 110°C~130°C, and the temperature of the second oxidation can be increased to 60°C~105°C, thereby effectively improving the efficiency and effect of oxidative digestion. In the prior art, the digestion colorimetric module 1 is set on the microfluidic chip 100. Due to the material (PMMA, PDMS and other materials) of the microfluidic chip 100, a higher temperature digestion (generally <60°C) cannot be used, resulting in low digestion efficiency and poor effect.

[0121] In addition, in the prior art, colored substances will be adsorbed on the microfluidic chip 100 and heating will cause aging of the microfluidic chip 100. Therefore, placing the digestion colorimetric module 1 at the outer end of the microfluidic chip 100 can extend the service life of the light source and the microfluidic chip 100.

[0122] 3. The present application method can automatically judge whether to start secondary digestion, which can ensure the test accuracy while shortening the test time, making the instrument more intelligent.

[0123] 4. The compensation algorithm of the method of the present application can eliminate the influence of complex water sample reaction process and the influence of light absorbing substances, which can further improve the accuracy.

[0124] In the second aspect of the present application, the present application proposes a system for implementing the above embodiment method. According to the embodiment of the present application, referring to the attached Figure 3 The system includes: a microfluidic chip 100, on which a metering module 2 and a flow channel are arranged, and a plurality of valves are arranged on the flow channel, and the inlet and flow direction of the water sample to be tested, pure water, standard solution, the first oxidant, the second oxidant, the reducing agent and the developer are controlled by controlling the valves on the flow channel; a digestion colorimetric module 1, which is connected to the metering module 2; a three-way valve 24, which is arranged between the digestion colorimetric module 1 and the metering module 2; a first peristaltic pump 20, which is connected to the metering module 2; a second peristaltic pump 22, which is connected to the digestion colorimetric module 1.

[0125] According to some specific embodiments of the present application, Figure 3 The system also includes: a water sample supply unit 13 to be tested, a first valve 3 and a fifth valve 7 are arranged between the water sample supply unit 13 to be tested and the metering module 2; a pure water supply unit 14, a second valve 4, a fourth valve 6 and a fifth valve 7 are arranged between the pure water supply unit 14 and the metering module 2; a standard solution supply unit 15, a third valve 5 and a fifth valve 7 are arranged between the standard solution supply unit 15 and the metering module 2; a reducing agent supply unit 16, a sixth valve 8 is arranged between the reducing agent supply unit 16 and the metering module 2; a color developer supply unit 17, a seventh valve 9 is arranged between the color developer supply unit 17 and the metering module 2; a first oxidant supply unit 19, a tenth valve 11 is arranged between the first oxidant supply unit 19 and the metering module 2; a second oxidant supply unit 18, an eighth valve 10 is arranged between the second oxidant supply unit 18 and the metering module 2; and a ninth valve 12 is also arranged between the metering module 2 and the air end 21.

[0126] It should be noted that the digestion and colorimetry module may be provided as an integrated unit, or the digestion module and the colorimetry module may be provided separately.

[0127] The system of the present application sets the digestion colorimetric module separately from the microfluidic chip (that is, the digestion colorimetric module is not set on the microfluidic chip), and places the digestion colorimetric module at the outer end of the microfluidic chip, which can increase the temperature of the first oxidation and the second oxidation occurring on the digestion colorimetric module. The temperature of the first oxidation can be increased to 110°C~130°C, and the temperature of the second oxidation can be increased to 60°C~105°C, thereby effectively improving the efficiency and effect of oxidative digestion. In the prior art, the digestion colorimetric module is set on the microfluidic chip. Due to the material (PMMA, PDMS and other materials), the microfluidic chip cannot be digested at a higher temperature (generally <60°C), resulting in low digestion efficiency and poor effect. Therefore, the system of the present application can test water samples with more complex working conditions, which can not only effectively remove chromatic interference, but also improve the digestion efficiency of total phosphorus, and ensure the accuracy and stability of total phosphorus testing.

[0128] In addition, in the prior art, colored substances will be adsorbed on the microfluidic chip and heating will cause aging of the microfluidic chip. Therefore, placing the digestion colorimetric module at the outer end of the microfluidic chip can extend the service life of the light source and the microfluidic chip.

[0129] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0130] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for microfluidic detection of total phosphorus water quality by eliminating impurity interference, characterized in that: include: (1) using at least two standard solutions for calibration to obtain a standard curve, wherein the at least two standard solutions are potassium dihydrogen phosphate solutions of different concentrations; Step (1) includes: (1-1) sequentially transmitting a preset volume of a first standard solution and a preset volume of a first oxidant to a digestion colorimetric module, so that the first oxidant digests the first standard solution to obtain a digestion signal I 标1 ; (1-2) delivering a preset volume of pure water to the digestion colorimetric module; (1-3) Sending a preset volume of reducing agent to the digestion colorimetric module to obtain a digestion signal I 标2 ; (1-4) The preset volume of the colorimetric reagent is transferred to the digestion colorimetric module to obtain a digestion signal. I 标3 ; (1-5) Cleaning the digestion colorimetric module; (1-6) Sending a preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 标4 ; (1-7) According to the I 标3 and stated I 标4 The signal of the first standard solution is calculated; (1-8) According to steps (1-1) to (1-7), calculate the absorbance of the second standard solution; (1-9) fitting the standard curve according to the relationship between the concentration and absorbance of the first standard solution and the relationship between the concentration and absorbance of the second standard solution; (2) Test the water sample to be tested, including: (2-1) Sending a preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 0; (2-2) sequentially transmitting a preset volume of the water sample to be tested and a preset volume of the first oxidant to the digestion colorimetric module, so that the first oxidant performs a first digestion on the water sample to be tested to obtain a digestion signal I 水1 ; (2-3) When lg(I0 / I 水1 )>lg(I 标4 / I 标1 )+b, delivering a preset volume of the second oxidant to the digestion colorimetric module so that the second oxidant performs a second digestion on the water sample to be tested, and the b value is 0.0005-0.008; When lg(I0 / I 水1 )≤lg(I 标4 / I 标1 )+b, delivering a preset volume of pure water to the digestion colorimetric module; (2-4) The preset volume of the reducing agent is transferred to the digestion colorimetric module to obtain a digestion signal. I 水2 ; (2-5) The color developer of the preset volume is transferred to the digestion colorimetric module to obtain a digestion signal. I 水3 ; (2-6) Cleaning the digestion colorimetric module; (2-7) Sending a preset volume of pure water to the digestion colorimetric module to obtain a reference signal I 水4 ; (2-8) According to the I 水2 , I 水3 , I 水4 Calculate the absorbance of the water sample to be tested, and calculate the concentration of the water sample to be tested according to the absorbance of the water sample to be tested and the standard curve, wherein when When , the absorbance of the water sample to be tested is calculated using a compensated absorbance algorithm, and the c value is 0.0005~0.008; when When the absorbance of the water sample to be tested is calculated using an uncompensated absorbance algorithm; In steps (2-8), the compensated absorbance algorithm: The uncompensated absorbance algorithm: And 水样 =lg( I 水4 / I 水3 ) Among them, A 水样 is the absorbance of the water sample to be tested, V1 represents the volume of the water sample to be tested; V2 represents the volume of the first oxidant; V3 represents the volume of the second oxidant or the pure water in step (2-3); V4 represents the volume of the reducing agent; and V5 represents the volume of the developer.

2. The method for microfluidic detection of total phosphorus water quality by eliminating impurity interference according to claim 1, characterized in that: The first oxidant is a 25 g / L to 50 g / L potassium persulfate aqueous solution; And / or, the second oxidant is a 10 g / L to 20 g / L potassium permanganate aqueous solution; And / or, the reducing agent is a 30 g / L to 100 g / L ascorbic acid aqueous solution; And / or, the developer is an aqueous solution including potassium antimony tartrate, ammonium molybdate and sulfuric acid, the concentration of potassium antimony tartrate is 0.35g / L~0.7g / L, the concentration of ammonium molybdate is 13g / L~26g / L, and the concentration of sulfuric acid is 15wt%~40wt%.

3. The method for microfluidic detection of total phosphorus water quality by eliminating impurity interference according to claim 1, characterized in that: In step (1-1), a preset volume of the first oxidant is transferred to the digestion colorimetric module, heated to 110°C to 130°C, and digested for 1 min to 30 min to obtain a digestion signal. I 标1 .

4. The method for microfluidic detection of total phosphorus water quality by eliminating impurity interference according to claim 1, characterized in that: In step (1-3), a preset volume of the reducing agent is transferred to the digestion colorimetric module and reduced at 40°C to 50°C for 30s to 10min to obtain a digestion signal. I 标2 ; And / or, in step (1-4), a preset volume of the color developer is transferred to the digestion colorimetric module, and the color is developed at 40°C to 50°C for 30s to 10min to obtain a digestion signal I 标3 .

5. The method for microfluidic detection of total phosphorus water quality by eliminating impurity interference according to claim 1, characterized in that: In step (2-2), a preset volume of the first oxidant is transferred to the digestion colorimetric module, heated to 110°C to 130°C, and digested for 1 min to 30 min to obtain a digestion signal. I 水1 ; And / or, in step (2-3), a preset volume of the second oxidant is transferred to the digestion colorimetric module, heated to 60° C. to 105° C., and digested for 1 min to 10 min.

6. The method for microfluidic detection of total phosphorus water quality by eliminating impurity interference according to claim 1, characterized in that: In step (2-4), a preset volume of the reducing agent is transferred to the digestion colorimetric module and reduced at 40°C to 50°C for 30s to 10min to obtain a digestion signal. I 水2 ; And / or, in step (2-5), a preset volume of the color developer is transferred to the digestion colorimetric module, and the color is developed at 40°C to 50°C for 30s to 10min to obtain a digestion signal I 水3 .

7. A system for implementing the method according to any one of claims 1 to 6, characterized in that: include: A microfluidic chip, wherein a metering module and a flow channel are provided on the microfluidic chip, and a plurality of valves are provided on the flow channel, and the inlet and flow direction of the water sample to be tested, pure water, standard solution, first oxidant, second oxidant, reducing agent and developer are controlled by controlling the valves on the flow channel; A digestion and colorimetric module, wherein the digestion and colorimetric module is connected to the metering module; A three-way valve, the three-way valve is arranged between the digestion colorimetric module and the metering module; a first peristaltic pump, wherein the first peristaltic pump is connected to the metering module; A second peristaltic pump, wherein the second peristaltic pump is connected to the digestion colorimetric module; A water sample supply unit to be tested, wherein a first valve and a fifth valve are arranged between the water sample supply unit to be tested and the metering module; A pure water supply unit, wherein a second valve, a fourth valve and the fifth valve are arranged between the pure water supply unit and the metering module; A standard solution supply unit, wherein a third valve and a fifth valve are provided between the standard solution supply unit and the metering module; a reducing agent supply unit, wherein a sixth valve is provided between the reducing agent supply unit and the metering module; a developer supply unit, wherein a seventh valve is provided between the developer supply unit and the metering module; a first oxidant supply unit, wherein a tenth valve is disposed between the first oxidant supply unit and the metering module; a second oxidant supply unit, wherein an eighth valve is provided between the second oxidant supply unit and the metering module; A ninth valve is also arranged between the metering module and the air end.

Images