CN118130441B - In-situ detection system and in-situ detection method for ammonia nitrogen content in water - Google Patents
In-situ detection system and in-situ detection method for ammonia nitrogen content in water Download PDFInfo
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- CN118130441B CN118130441B CN202410481907.8A CN202410481907A CN118130441B CN 118130441 B CN118130441 B CN 118130441B CN 202410481907 A CN202410481907 A CN 202410481907A CN 118130441 B CN118130441 B CN 118130441B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
- B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
- B01L3/502—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures
- B01L3/5027—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
- G01N21/6428—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes"
- G01N21/643—Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" non-biological material
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Abstract
The invention discloses an in-situ detection system and an in-situ detection method for ammonia nitrogen content in water. The in-situ detection system for the ammonia nitrogen content in the water quality comprises: the device comprises a detection micro-fluidic chip, a sample liquid inlet pipeline and a molecular fluorescence detection reagent pipeline. The invention discloses a method for in-situ detection of ammonia nitrogen content in water by combining a microfluidic technology with a molecular fluorescence method, wherein samples are subjected to pretreatment, mixed reaction and detection on a microfluidic chip through sequential sample injection of a pump and an electromagnetic valve, and the whole detection system has the advantages of high automation degree, small sample consumption, simplicity in operation and suitability for in-situ analysis.
Description
Technical Field
The invention belongs to the technical field of environmental protection water quality detection, and particularly relates to an in-situ detection system and an in-situ detection method for ammonia nitrogen content in water quality.
Background
Ammonia nitrogen is a nutrient substance of algae substances, and exists in water in the form of free ammonia (NH 3) and ammonium ions (NH 4 +), and excessive ammonia can cause eutrophication of water, so that the water is anoxic, the water quality is deteriorated, and aquatic organisms such as fish cannot survive. The method for monitoring the change of the ammonia nitrogen concentration in the water body has important significance for water body pollution, marine geochemical circulation, ecological disaster early warning and the like.
The traditional determination method of ammonia nitrogen content in water is a Navier reagent photometry, but because calcium and magnesium ions contained in water are easy to react with Navier reagent, the water sample is turbid and the determination is disturbed, so that corresponding pretreatment is needed, the operation is complicated, and toxic compounds are contained in the used reagent, so that secondary pollution is caused to the environment.
At present, a molecular fluorescence method is generally adopted for detecting ammonia nitrogen concentration, and the principle is that in an alkaline medium, phthalic aldehyde (OPA) reacts with ammonia nitrogen to generate an isoindole derivative with fluorescence, a water sample is irradiated by excitation light with specific wavelength, and the content of ammonia nitrogen is determined according to the generated fluorescence intensity change.
For example, the invention application with publication number of CN104764726A discloses a water quality monitoring instrument and a method thereof, according to the reaction of phthalic dicarboxaldehyde in a reagent solution and ammonia nitrogen in the water sample, an isoindole derivative solution is generated; the detection system is used for detecting the fluorescence value of the isoindole derivative solution and measuring the ammonia nitrogen content in the water sample.
For another example, the invention application publication No. CN107091823A discloses a low-concentration ammonia nitrogen fluorescence detection solid reagent and a detection method thereof, wherein the low-concentration ammonia nitrogen fluorescence detection solid reagent comprises a sodium sulfite-buffer reagent packet and a phthalaldehyde reagent packet, and the sodium sulfite-buffer reagent packet comprises 30-40wt% of sodium sulfite, 5-15wt% of borax, 0-1wt% of lithium hydroxide and 50-60wt% of sodium chloride; the phthalic dicarboxaldehyde reagent package is composed of phthalic dicarboxaldehyde. Compared with the traditional detection method, the reagent in the method is easier to store, the detection method is more convenient and the detection result is more accurate.
The ammonia nitrogen detection reagent prepared by adopting the fluorescence method has the advantages of simple preparation, no toxicity, good stability, but has the defects of low automation degree, large equipment size, large sample consumption and the like. Therefore, if an in-situ fluorescence ammonia nitrogen detection system with less reagent consumption, stable performance and high integration level can be developed, the detection efficiency can be greatly improved, the water quality state information can be accurately provided for related personnel in real time, and the system has important application potential in the field of environmental protection water quality monitoring.
Disclosure of Invention
The invention provides an in-situ detection system and an in-situ detection method for ammonia nitrogen content in water quality aiming at the defects in the prior art.
An in situ detection system for ammonia nitrogen content in water quality, comprising:
The detection microfluidic chip is provided with a flow channel for detection, the head end and the tail end of the flow channel are respectively provided with a liquid inlet and a liquid outlet, and the flow channel comprises a mixing area and a detection area; the mixing zone is used for mixing a molecular fluorescence detection reagent with a water quality sample to be detected to obtain a mixed solution; the detection zone is positioned downstream of the mixing zone and is used for receiving the mixed solution; the detection area is also provided with a fluorescence intensity detection mechanism for detecting the fluorescence intensity of the mixed solution in the detection area, and the fluorescence intensity detection mechanism comprises a light source for irradiating excitation light to the detection area and a signal receiver for detecting the fluorescence intensity of the mixed solution in the detection area;
the sample liquid inlet pipeline is used for conveying a water quality sample to be detected to the detection microfluidic chip through the liquid inlet;
and the molecular fluorescence detection reagent pipeline is used for conveying a molecular fluorescence detection reagent for detecting ammonia nitrogen content by a molecular fluorescence method to the detection microfluidic chip through the liquid inlet.
Preferably, the sample liquid inlet pipeline is provided with a first electromagnetic valve, a pretreatment filter, a one-way valve, a metering tube and an infusion pump in sequence from a liquid inlet end to a liquid outlet end.
More preferably, the first electromagnetic valve is a two-in one-out three-way electromagnetic valve, wherein one inlet and one outlet are connected into the sample liquid inlet pipeline, and the other inlet is used for feeding cleaning liquid.
More preferably, the molecular fluorescence detection reagent pipeline and the sample liquid inlet pipeline share the same pipeline, the sample liquid inlet pipeline is further provided with a second electromagnetic valve between the one-way valve and the metering pipe, the second electromagnetic valve is a two-in one-out three-way electromagnetic valve, one inlet and one outlet are connected into the sample liquid inlet pipeline, and the other inlet is used for detecting the reagent by the molecular fluorescence detection method.
Preferably, the mixing area is a serpentine flow channel, and a plurality of auxiliary mixing units are arranged at intervals, and the flow channels in each auxiliary mixing unit are branched and then recombined.
More preferably, the flow passage in the mixing assisting unit is branched into two or more. If split into two strands, the two strands may have different shapes such as oval or diamond.
Preferably, the in-situ detection system for ammonia nitrogen content in water quality further comprises a heating module, wherein the heating module comprises a mixing zone heating module and a detection zone heating module, the mixing zone heating module is arranged at the back of the detection microfluidic chip and corresponds to the position of the mixing zone, and the detection zone heating module is arranged at the back of the detection microfluidic chip and corresponds to the position of the detection zone.
More preferably, the periphery of the mixing zone heating module and the periphery of the detection zone heating module are respectively provided with a heat insulation groove.
Through the arrangement of the two heating modules, the liquid in the mixing area and the detection area can be heated, and the mixing reaction efficiency of the water quality sample to be detected and the detection reagent by the molecular fluorescence method is improved. And the heat insulation groove isolates the two heating modules, so that the influence of high temperature on other elements is avoided, and the detection stability is improved.
Preferably, the detecting microfluidic chip further comprises a circuit board module, the flow channel is arranged on the top surface of the circuit board module, and the circuit board module further comprises a control mechanism for controlling the detecting microfluidic chip to operate.
The detection area is provided with an inlet and an outlet, the inlet is used for liquid inlet, the outlet is used for liquid outlet, the inlet is connected with the mixing area, and the outlet is connected with a liquid outlet at the tail end of a flow channel of the whole detection microfluidic chip. The entrance of the detection area is lower than the exit, so that possible bubble aggregation in the detection area is reduced.
Preferably, the bottom surface and the side surface of the cavity of the detection area are coated with a high-reflectivity material except the side where the light source is located, such as Teflon AF2400, and multiple reflections are used for enhancing fluorescent signals generated by the solution in the detection area, so that the detection sensitivity is improved.
The invention also provides an in-situ detection method for the ammonia nitrogen content in the water, which uses an in-situ detection system for the ammonia nitrogen content in the water, and comprises the following steps:
(1) Distilled water is input into the detection microfluidic chip through the sample liquid inlet pipeline, the fluorescence intensity detection mechanism detects the fluorescence intensity of the detection area, and the fluorescence signal is used as a background signal after being stabilized;
(2) Inputting a water quality sample to be detected into the detection microfluidic chip through the sample liquid inlet pipeline, inputting a molecular fluorescence method detection reagent into the detection microfluidic chip through the molecular fluorescence method detection reagent pipeline, enabling the water quality sample to be detected and the molecular fluorescence method detection reagent to enter a detection area after mixed reaction in a mixing area,
(3) And (3) detecting the fluorescence intensity of the detection area by a fluorescence intensity detection mechanism, and obtaining a detection signal after the fluorescence signal is stable, thereby obtaining the ammonia nitrogen concentration in the water quality sample to be detected.
Preferably, a dark field detection mode is used in detection, wherein the dark field detection mode is to firstly start the light source to irradiate a detection area for a certain time, then turn off the light source, and the solution still emits a fluorescent signal for a short period of time due to the afterglow effect, so that the influence of excitation light on detection can be eliminated. For example, the fluorescent signal is collected by the signal receiver at 4 ns-10 ns after the light source is turned off.
Preferably, the detection area is square in shape and has a cross-sectional area S0. The light source is positioned on one side of the detection area, and the signal receiver is positioned above the detection area. During detection, if the signal receiver shoots that bubbles exist on the top surface of the inner cavity of the detection area, the bubble area is S1, and the fluorescence signal intensity is A0 at the moment, the fluorescence signal intensity is corrected, and the corrected fluorescence signal intensity is A1=A0/(S0-S1). Through the correction, the interference of bubbles can be reduced, and the detection accuracy is improved.
The invention has the beneficial effects that:
The invention discloses a method for in-situ detection of ammonia nitrogen content in water by combining a microfluidic technology with a molecular fluorescence method, wherein samples are subjected to pretreatment, mixed reaction and detection on a microfluidic chip through sequential sample injection of a pump and an electromagnetic valve, and the whole detection system has the advantages of high automation degree, small sample consumption, simplicity in operation and suitability for in-situ analysis.
Drawings
FIG. 1 is a schematic diagram of the overall structure of an in-situ detection system for ammonia nitrogen content in water.
Fig. 2 is a schematic diagram of the structure of a mixing zone serpentine flow channel.
Fig. 3 is a schematic side view of a detection microfluidic chip.
Fig. 4 is a schematic back view of a circuit board module.
Reference numerals: the device comprises a first electromagnetic valve 1, a pretreatment filter 2, a solution filtering area 3, a fluid conveying pipe 4, a one-way valve 5, a second electromagnetic valve 6, a metering pipe 7, an infusion pump 8, a detection micro-fluidic chip 9, a circuit board module 10, a mixing area 11, a detection area 12, a light source 13, a signal receiver 14, a power supply unit 15, a temperature regulation unit 16, a light source driving unit 17, a signal conditioning unit 18, a communication unit 19, a heating module 20 and a heat insulation groove 21.
Detailed Description
As shown in FIG. 1, the in-situ detection system for ammonia nitrogen content in water comprises a sample liquid inlet pipeline, a molecular fluorescence detection reagent pipeline, a detection micro-fluidic chip and a fluorescence intensity detection mechanism.
The sample liquid inlet pipeline is used for conveying a water quality sample to be detected to the detection microfluidic chip. The sample liquid inlet pipeline is sequentially provided with a first electromagnetic valve 1, a pretreatment filter 2, a one-way valve 5, a metering tube 7 and an infusion pump 8 from a liquid inlet end to a liquid outlet end.
The first electromagnetic valve 1 is a two-in one-out three-way electromagnetic valve, wherein one inlet and one outlet are connected into a sample liquid inlet pipeline, and the other inlet is used for feeding cleaning liquid. That is, in fig. 1, the inlet S is used for feeding a water quality sample to be measured, the inlet C is used for feeding a cleaning liquid, and the first solenoid valve 1 can switch the feeding liquid between the inlet S and the inlet C as needed. Distilled water can be used as the cleaning liquid in the application, and the cleaning liquid is used for clear flow paths.
The pretreatment filter 2 is used for filtering and removing impurities from the water quality sample to be tested. The pretreatment filter 2 may be a pretreatment microfluidic chip including a solution filtration zone 3. The pretreatment filter 2 may be prepared by 3D printing or bonded with Polydimethylsiloxane (PDMS) and glass, or may be prepared in other ways. The solution filtering area 3 is internally provided with a filtering column, and the shape, the size and the distance of the filtering column can be adjusted according to the thickness degree of impurities of a water sample and are used for filtering the impurities of the solution to be detected for the first time. Of course, the impurity can be removed by arranging a filter screen in the solution filtering area and filtering the solution through the filter screen.
The components of the sample liquid inlet pipeline are connected through a fluid conveying pipe 4. The fluid conveying pipe 4 is made of polytetrafluoroethylene pipe or silicone pipe, which can resist corrosion of high-salt solution and other solutions while meeting the requirement of rapid flow of the solution.
The pretreatment filter 2 is communicated with the one-way valve 5 through the fluid conveying pipe 4, and a filter membrane is arranged at the inlet of the one-way valve 5 and is used for carrying out secondary filtration on a water quality sample to be tested, and the filter membrane is preferably a microporous filter membrane of 0.45 micrometers. By the secondary filtration, the impurity particles can be sufficiently removed.
In a preferred embodiment, the molecular fluorescence detection reagent pipeline and the sample liquid inlet pipeline share the same pipeline, the sample liquid inlet pipeline is further provided with a second electromagnetic valve 6 between the one-way valve 5 and the metering tube 7, the second electromagnetic valve 6 is a two-in one-out three-way electromagnetic valve, one inlet and one outlet are connected into the sample liquid inlet pipeline, and the other inlet D is used for detecting the reagent by the molecular fluorescence method.
In order to facilitate accurate measurement of the flowing volume of each solution in the detection process, the solution injection is preferably controlled by adopting a mode of combining a metering tube 7 and an infusion pump 8 in the embodiment. The metering tube 7 is preferably an optoelectronic metering tube, and the infusion pump 8 is preferably a peristaltic pump.
In the invention, the three-way electromagnetic valve selected from the first electromagnetic valve 1 and the second electromagnetic valve 6 is preferably made of PEEK material so as to prevent the corrosion of the high-salt waiting sample solution.
The detection microfluidic chip 9 is provided with a flow channel for detection, the head end and the tail end of the flow channel are respectively provided with a liquid inlet and a liquid outlet, and the flow channel comprises a mixing area 11 and a detection area 12. The mixing zone 11 is used for mixing a molecular fluorescence detection reagent with a water quality sample to be detected to obtain a mixed solution; the detection zone 12 is located downstream of the mixing zone 11 for receiving the mixed solution.
The detection microfluidic chip 9 further comprises a circuit board module 10, and the flow channel of the detection microfluidic chip 9 is arranged on the top surface of the circuit board module 10. A flow channel of the detection microfluidic chip 9 may be formed using Polydimethylsiloxane (PDMS) and circuit board bonding.
As shown in fig. 1 and 2, in order to improve the mixing efficiency, the mixing area 11 is a serpentine flow channel, and a plurality of auxiliary mixing units are arranged at intervals, and the flow channel in each auxiliary mixing unit is branched and then recombined. The flow channel in the auxiliary mixing unit is bifurcated into two strands which form an oval shape. Therefore, the serpentine flow channels of the mixing zone 11 form a "total-split-total" unit structure, and after the solution enters the branched flow channels, the solution is converged from the branched flow channels, and the solution mixing reaction efficiency is improved by splitting, mutual collision, and the like of the solution. The mixing efficiency is improved, so that the total flow length of the mixing zone 11 can be as short as possible, the space of the detection microfluidic chip 9 is fully utilized, and the sample consumption is reduced.
As shown in fig. 1 and 3, the detection area 12 has an inlet for liquid and an outlet for liquid, the inlet is connected to the mixing area 11, and the outlet is connected to the liquid outlet W at the end of the flow channel of the whole detection microfluidic chip 9. The entrance to the detection zone 12 is lower than the exit, reducing the possible accumulation of bubbles in the detection zone 12. Optimally, the inlet is at the lowest position on one side of the detection area 12, and the outlet is at the highest position on the opposite side of the detection area 12, so that bubbles generated in the liquid flowing process are accumulated at the top of the chamber and are removed from the outlet channel, interference to optical signals is avoided, and detection accuracy is improved.
In a preferred embodiment, the bottom and sides of the chamber in the detection zone 12 are coated with a highly reflective material, such as Teflon AF2400, except on the side where the light source is located, and multiple reflections are used to enhance the fluorescence signal generated by the solution in the detection zone 12 and to increase the detection sensitivity.
The surface of the detection area 12 corresponding to the circuit board is provided with a nano gold film, the reflectivity of fluorescent signals generated by the solution at the detection area 12 is enhanced, and the detection zero sensitivity is improved, wherein the thickness of the nano gold film is 30-50 nm, and the requirements of low reflectivity of light source signals and high reflectivity of fluorescent signals are met.
The detection area 12 is also provided with a fluorescence intensity detection mechanism for detecting the fluorescence intensity of the mixed solution in the detection area 12, and the fluorescence intensity detection mechanism comprises a light source 13 for irradiating excitation light to the detection area 12 and a signal receiver 14 for detecting the fluorescence intensity of the mixed solution in the detection area 12. The light source 13 may be an LED lamp with a central wavelength of 360-370nm. The signal receiver 14 may employ a camera, preferably a camera with a response band of 400-700 nm. Preferably, in order to eliminate the influence of stray light on detection, a first optical filter is arranged between the light source 13 and the detection area 12, the central wavelength is 360-370nm, a second optical filter is arranged between the detection area 12 and the signal receiver 14, and the central wavelength is 420nm.
As shown in fig. 4, in a preferred embodiment, the in-situ detection system for ammonia nitrogen content in water according to the present invention further includes a heating module 20, where the heating module includes a mixing zone heating module and a detection zone heating module, the mixing zone heating module is disposed at a position corresponding to the mixing zone 11 on the back of the detection microfluidic chip 9, and the detection zone heating module is disposed at a position corresponding to the detection zone 12 on the back of the detection microfluidic chip. The periphery of the mixing zone heating module and the periphery of the detection zone heating module are respectively provided with a heat insulation groove 21. By arranging the two heating modules 20, the liquid in the mixing zone 11 and the liquid in the detection zone 12 can be heated, and the mixing reaction efficiency of the water quality sample to be detected and the detection reagent by the molecular fluorescence method can be improved. The heat insulation groove 21 isolates the two heating modules 20, so that the influence of high temperature on other elements is avoided, and the detection stability is improved. The heating module 20 is preferably a high power chip resistor.
The heating module of the mixing zone is adjustable within the temperature range of 35-90 ℃ and is used for improving the mixing reaction efficiency of the water quality sample to be detected and the detection reagent by the molecular fluorescence method and shortening the reaction time. The heating module of the detection area is adjustable within the temperature range of 35-60 ℃ and is used for maintaining the temperature of the detection solution and reducing the influence of the temperature on the detection result. The two temperature zones are provided to reduce the effect of heat radiation from the heating module at high temperatures on the signal receiver 14.
The substrate material of the circuit board module 10 may be a polyimide film, which is thin to easily conduct heat generated by the heating element 20.
The circuit board module 10 is also provided with a control mechanism for controlling the operation of the detection microfluidic chip 9. The control mechanism comprises a power supply unit 15, a temperature regulating unit 16, a light source driving unit 17, a signal conditioning unit 18 and a communication unit 19. The power supply unit 15 is used for providing power required by the circuit board module 10. The temperature regulation unit 16 is used for temperature regulation of the heating module 10. The light source driving unit 17 is used for controlling the light source 13, and can modulate the signal intensity by using square waves. The signal conditioning unit 18 is configured to receive the signal output by the processing signal receiver 14, and wirelessly transmit (wifi, bluetooth, etc.) to a user terminal or a detection center through the communication unit 19.
The in-situ detection system for the ammonia nitrogen content in the water quality is used for detecting the ammonia nitrogen content in the water quality, a molecular fluorescence method detection reagent is prepared before detection, phthalic aldehyde (OPA) in the molecular fluorescence method detection reagent can react with ammonia nitrogen in a water quality sample to be detected to generate an isoindole derivative with fluorescence, a water sample is irradiated by excitation light with specific wavelength, and the ammonia nitrogen content is determined according to the generated fluorescence intensity change. A preferred preparation method of the molecular fluorescence detection reagent is as follows:
Weighing 5.0g of tetraboric acid to dissolve in 100mL of water, and stirring until the tetraboric acid is completely dissolved for later use; weighing 0.06g of sodium sulfite to dissolve in 50mL of water, and stirring until the sodium sulfite is completely dissolved for later use; 1.00g of phthalic dicarboxaldehyde is weighed and dissolved in 25mL of absolute ethyl alcohol, and stirred until the phthalic dicarboxaldehyde is completely dissolved; mixing the three solutions, adding water to 250mL, and obtaining the molecular fluorescence detection reagent.
The in-situ detection method for detecting the ammonia nitrogen content in water quality comprises the following steps:
(1) Distilled water is input into the detection microfluidic chip through a sample liquid inlet pipeline, the fluorescence intensity detection mechanism detects the fluorescence intensity of the detection area, and the fluorescence signal is used as a background signal after being stabilized;
(2) Inputting a water quality sample to be detected into the detection microfluidic chip through a sample liquid inlet pipeline, inputting a molecular fluorescence method detection reagent into the detection microfluidic chip through a molecular fluorescence method detection reagent pipeline, enabling the water quality sample to be detected and the molecular fluorescence method detection reagent to enter a detection area after mixing reaction in a mixing area,
(3) And (3) detecting the fluorescence intensity of the detection area by a fluorescence intensity detection mechanism, and obtaining a detection signal after the fluorescence signal is stable, thereby obtaining the ammonia nitrogen concentration in the water quality sample to be detected.
When in detection, a dark field detection mode is used, wherein the dark field detection mode is to firstly start a light source to irradiate a detection area for a certain time, then turn off the light source, and the solution still continuously emits fluorescent signals for a short period of time due to the afterglow effect, so that the influence of excitation light on detection can be eliminated when the detection is carried out. For example, the fluorescent signal is collected by the signal receiver at about 4ns to 10ns after the light source is turned off.
In the step (2), the volume ratio of the molecular fluorescence detection reagent to the water quality sample to be detected is 1:5-1:10.
The detection area is square in shape and S0 in cross-sectional area. The light source is positioned at one side of the detection area, and the signal receiver is positioned above the detection area. During detection, if the top surface of the inner cavity of the detection area is provided with bubbles by shooting through the signal receiver, and the bubble area is S1, and the fluorescence signal intensity is A0 at the moment, the fluorescence signal intensity is corrected, and the corrected fluorescence signal intensity is A1=A0/(S0-S1). Through the correction, the interference of bubbles can be reduced, and the detection accuracy is improved.
Claims (7)
1. An in-situ detection method for ammonia nitrogen content in water quality is characterized in that an in-situ detection system for ammonia nitrogen content in water quality is used, and the in-situ detection system for ammonia nitrogen content in water quality comprises:
The detection microfluidic chip is provided with a flow channel for detection, the head end and the tail end of the flow channel are respectively provided with a liquid inlet and a liquid outlet, and the flow channel comprises a mixing area and a detection area; the mixing zone is used for mixing a molecular fluorescence detection reagent with a water quality sample to be detected to obtain a mixed solution; the detection zone is positioned downstream of the mixing zone and is used for receiving the mixed solution; the detection area is also provided with a fluorescence intensity detection mechanism for detecting the fluorescence intensity of the mixed solution in the detection area, and the fluorescence intensity detection mechanism comprises a light source for irradiating excitation light to the detection area and a signal receiver for detecting the fluorescence intensity of the mixed solution in the detection area;
the sample liquid inlet pipeline is used for conveying a water quality sample to be detected to the detection microfluidic chip through the liquid inlet;
the molecular fluorescence method detection reagent pipeline is used for conveying a molecular fluorescence method detection reagent for detecting ammonia nitrogen content by a molecular fluorescence method to the detection microfluidic chip through the liquid inlet;
the mixing area is a serpentine flow channel and is provided with a plurality of auxiliary mixing units at intervals, and the flow channels in each auxiliary mixing unit are branched and then recombined;
The flow passage in the mixing assisting unit is bifurcated into two or more than two;
The in-situ detection method comprises the following steps:
(1) Distilled water is input into the detection microfluidic chip through the sample liquid inlet pipeline, the fluorescence intensity detection mechanism detects the fluorescence intensity of the detection area, and the fluorescence signal is used as a background signal after being stabilized;
(2) Inputting a water quality sample to be detected into the detection microfluidic chip through the sample liquid inlet pipeline, inputting a molecular fluorescence method detection reagent into the detection microfluidic chip through the molecular fluorescence method detection reagent pipeline, and enabling the water quality sample to be detected and the molecular fluorescence method detection reagent to enter a detection area after mixing reaction in a mixing area;
(3) Detecting the fluorescence intensity of the detection area by a fluorescence intensity detection mechanism, and obtaining a detection signal after the fluorescence signal is stable, thereby obtaining the ammonia nitrogen concentration in the water quality sample to be detected;
In the detection process, a dark field detection mode is used, wherein the dark field detection mode is to firstly start a light source to irradiate a detection area for a certain time, then turn off the light source, and collect fluorescent signals by a signal receiver when the light source is turned off for 4-10 ns;
The shape of the detection area is square, and the cross section area is S0; the light source is positioned at one side of the detection area, and the signal receiver is positioned above the detection area; during detection, if the top surface of the inner cavity of the detection area is provided with bubbles by shooting through the signal receiver, and the bubble area is S1, and the fluorescence signal intensity is A0 at the moment, the fluorescence signal intensity is corrected, and the corrected fluorescence signal intensity is A1=A0/(S0-S1).
2. The in-situ detection method for ammonia nitrogen content in water according to claim 1, wherein the sample liquid inlet pipeline is sequentially provided with a first electromagnetic valve, a pretreatment filter, a one-way valve, a metering tube and an infusion pump from a liquid inlet end to a liquid outlet end.
3. The method for in-situ detection of ammonia nitrogen content in water according to claim 2, wherein the first electromagnetic valve is a two-in one-out three-way electromagnetic valve, one inlet and one outlet are connected to the sample liquid inlet pipeline, and the other inlet is used for feeding cleaning liquid.
4. The in-situ detection method for ammonia nitrogen content in water according to claim 2, wherein the molecular fluorescence detection reagent pipeline and the sample liquid inlet pipeline share the same pipeline, a second electromagnetic valve is further arranged between the one-way valve and the metering pipe in the sample liquid inlet pipeline, the second electromagnetic valve is a two-in one-out three-way electromagnetic valve, one inlet and one outlet are connected into the sample liquid inlet pipeline, and the other inlet is used for detecting the reagent by the molecular fluorescence detection method.
5. The in-situ detection method of ammonia nitrogen content in water according to claim 1, further comprising a heating module, wherein the heating module comprises a mixing zone heating module and a detection zone heating module, the mixing zone heating module is arranged at a position corresponding to the mixing zone on the back surface of the detection microfluidic chip, and the detection zone heating module is arranged at a position corresponding to the detection zone on the back surface of the detection microfluidic chip.
6. The method for in-situ detection of ammonia nitrogen content in water according to claim 5, wherein the periphery of the mixing zone heating module and the periphery of the detection zone heating module are respectively provided with a heat insulation groove.
7. The in-situ detection method of ammonia nitrogen content in water according to claim 1, wherein the detection microfluidic chip further comprises a circuit board module, the flow channel is arranged on the top surface of the circuit board module, and the circuit board module further comprises a control mechanism for controlling the operation of the detection microfluidic chip.
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| CN105866088A (en) * | 2016-05-20 | 2016-08-17 | 山东省科学院海洋仪器仪表研究所 | Device and method for on-line detection of content of ammonia nitrogen in seawater |
| CN115032370A (en) * | 2022-06-13 | 2022-09-09 | 中科合肥智慧农业协同创新研究院 | On-site detection device and detection method for soil nutrients |
| CN116359150A (en) * | 2023-04-07 | 2023-06-30 | 福建省水产研究所（福建水产病害防治中心） | In-situ detection device of optical fiber coupling micro-channel reaction system |
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| CN105866088A (en) * | 2016-05-20 | 2016-08-17 | 山东省科学院海洋仪器仪表研究所 | Device and method for on-line detection of content of ammonia nitrogen in seawater |
| CN115032370A (en) * | 2022-06-13 | 2022-09-09 | 中科合肥智慧农业协同创新研究院 | On-site detection device and detection method for soil nutrients |
| CN116359150A (en) * | 2023-04-07 | 2023-06-30 | 福建省水产研究所（福建水产病害防治中心） | In-situ detection device of optical fiber coupling micro-channel reaction system |
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