JP2011508227A - Colorimetric detection method and apparatus for ammonia nitrogen by flow injection - Google Patents

Abstract

  The present invention provides a method for colorimetric detection of ammonia nitrogen by flow injection. Capillary passage having a discharge solution by using a NaOH solution having a concentration of 0.01 mol / l to 0.03 mol / l as a discharge solution, injecting the discharge solution into a capillary channel system to which a gas-liquid separator including a deep groove is connected. A sample zone is injected into the sample zone to form a sample zone, and the sample zone circulates in the capillary system together with the discharge liquid by pumping, and passes through the deep groove of the gas-liquid separator. Release gas. The ammonia gas diffuses to the groove and permeates through the gas permeable membrane, discolors the acid-base indicator in the capillary groove, and continuously circulates through the sample zone until the end of the release of ammonia, thereby receiving the ammonia absorbed. Is transported to the flow cell of the colorimeter by an injection pump, irradiated with light having a wavelength of 560 nm, and the concentration of ammonia nitrogen in the test water is measured by photoelectric conversion.

Description

  The present invention belongs to the field of chemical analysis and water environment monitoring analysis, and detects the ammonia nitrogen content in water or solution, or the ammonia state by flow injection for online monitoring of the ammonia nitrogen content. The present invention relates to a colorimetric detection method for nitrogen.

Ammonia is nitrogen present in the form of nonionic ammonia (NH ₃ ) or ammonium ion (NH ₄ ⁺ ). When dissolved in water, a part of it reacts with water to convert ammonium ion. This is generically referred to as ammonia nitrogen because it forms and part of the other forms ammonia water (nonionic ammonia).

Ammonia exists in nature in a wide range of rivers, lakes, and seas as a decomposition product of nitrogen-containing organic substances. Ammonia in water changes to nitrite in an oxygen-containing environment, and in an oxygen-free environment, the nitrite is reduced to ammonia by the action of microorganisms, and can subsequently be changed to nitrate. Ammonia nitrogen in an aqueous solution refers to nitrogen present in the form of free ammonia (also referred to as nonionic ammonia (NH ₃ )) or ammonium ion (NH ₄ ⁺ ). When ammonia is dissolved in water, a part thereof reacts with water to produce ammonium ions, and the other part produces aqueous ammonia (nonionic ammonia).

  If the content of ammonia nitrogen in the water is too high, cyanobacteria grow explosively in the lake, harming human health and harmful to fish. Therefore, the content of ammonia nitrogen in water is a standard for how much water is contaminated with nitrogen-containing organic matter and must be strictly controlled. With the development of the economy, many industrial production produces a large amount of ammonia, becoming a source of ammonia pollution to the environment. For example, fertilizer production, nitric acid, coking, coal gas, nitrocellulose, rayon, synthetic rubber, calcium carbide, dyes, varnish, caustic soda, electroplating, oil mining and processing of petroleum products all produce ammonia pollution It is a factor. Therefore, online monitoring of ammonia nitrogen content is very important because it can always analyze industrial wastewater or rivers and lakes quickly and provide real time content data of ammonia nitrogen in water. This will take corresponding measures to ensure that the wastewater from companies reaches the discharge standard and that the content of ammonia nitrogen in rivers and lakes is within safety standards.

  Currently, methods for measuring ammonia nitrogen include spectrophotometric colorimetry (Nessler's method), acid-base neutralization titration method and ion electrode method mainly using salicylic acid-hypochlorite or mercury iodide as reagents. is there.

  The Nessler method is a typical method for measuring ammonia, and is a standard analytical method in many countries. An alkaline solution of mercury iodide and potassium iodide reacts with ammonia to produce a light reddish brown colloidal compound with strong absorption in a wide wavelength range. However, the reaction between Nessler's reagent and ammonia is actually a precipitation reaction. For turbid or colored samples, or samples that have both metal ions and organic substances that cause precipitation under alkaline conditions, it is necessary to perform pre-treatment after coagulation sedimentation or steam distillation, in addition to that, There are drawbacks that the toxicity of the reagent is strong and the sensitivity of the method is not high.

  In the colorimetric method using salicylic acid-hypochlorite, ammonium and phenol react with hypochlorite ions to form a blue compound in the presence of sodium nitroprusside. Such a reaction is called Berthelot reaction. And has maximum absorption at a wavelength of 697 nm. However, sodium hypochlorite is not stable and must be used immediately after it is prepared, so it is not suitable for use in unmonitored online equipment.

  The acid-base titration method requires heating and distilling the sample water, and the released ammonia is absorbed into the boric acid solution, methyl red-methylene blue as an indicator, and acid standard solution against ammonium in the distillate. Titrate. The measurement method is relatively complicated and takes time to measure. If the sample water contains water that can be distilled under these conditions and can react with an acid during titration, the value of the measurement result becomes high.

The present invention is a complicated operation, has toxicity of the reagent, or cannot store the reagent for a long period of time, such as spectrophotometry with a conventional Nessler reagent, spectrophotometry with salicylic acid-hypochlorite, ammonia electrode It overcomes the drawbacks in the detection method of the ammonium nitrogen, such as law, in order to realize automatic online detection for NH 3 _-N, easy to operate, fast, reliable, non-toxic reagents, also running costs An object of the present invention is to provide a method for detecting ammonia nitrogen by cheap flow injection and an apparatus for detecting ammonia nitrogen by flow injection therefor.

  In other words, the present invention

  The discharge solution is connected to a capillary channel system in which a NaOH solution having a concentration of 0.01 mol / l to 0.03 mol / l is used as a discharge solution and a gas-liquid separator including a deep groove capable of preventing contact between the sample and the gas permeable membrane is connected. A sample zone is formed by injecting a certain amount of test water into the capillary passage having the discharge liquid, and the sample zone is circulated in the capillary-gas-liquid separator channel system together with the discharge liquid by pumping. As it flows and passes through the deep groove of the gas-liquid separator, ammonia gas is released, this ammonia gas rises up to the groove opening, then permeates through the gas-permeable membrane, and the acid base in the capillary groove on the other side of the membrane Absorbed in the receiver solution containing the indicator, it becomes ammonium ions, discolors the acid-base indicator, continuously circulates through the sample zone to release ammonia, Flow for transporting to a colorimeter flow cell by a radiation pump, irradiating with light with a wavelength of 560 nm, measuring the photovoltage change when this light passes through the receiver, and calculating the concentration of ammonia nitrogen in the sample by conversion This is a method for detecting ammonia nitrogen by injection.

  The predetermined amount of the sample water is intermittently injected into the carrier liquid circulating by the sample injection valve to form a plurality of sample zones intermittently distributed in the circulating capillary-gas-liquid separator flow path. Alternatively, a certain amount of sample water is intermittently mixed with the discharge liquid to expedite the release and enrichment of ammonia gas.

  The received acid-base indicator containing the acid-base indicator is a weakly acidic bromothymol blue solution.

In this method, a dilute solution of NaOH also serves as a carrier solution that also serves as an ammonia releasing solution of a test sample, and ammonium ions and hydroxy groups in the sample react to generate ammonia gas, that is, NH ₄ ⁺⁺ OH ⁻ → NH _3. ⁺ H ₂ O. The test water circulates with the carrier liquid and releases ammonia gas as it passes through the gas-liquid separator. This ammonia gas permeates through the gas permeable membrane and enters the receiving liquid, and the acid-base indicator solution (hereinafter referred to as receiving liquid). As the ammonium ion increases, the alkalinity of the receiver liquid increases as the ammonium ion increases, and the acid-base indicator bromothymol blue changes from yellow-green to blue, and the blue increases the concentration of ammonium ions. Therefore, it is irradiated with light having a wavelength of 560 nm, and the photoelectric voltage when the light passes through the liquid receiver is measured by a photoelectric converter to obtain a response curve having a corresponding peak height. And the density | concentration of ammonia nitrogen in a test water is computable by comparing with the measured value of a known standard sample.

  In order to realize the above-described method for detecting ammonia nitrogen, the present invention has designed a device for detecting ammonia nitrogen by dedicated flow injection.

  This ammonia-nitrogen detection apparatus by flow injection includes a gas-liquid separator, a photoelectric detection flow cell, a discharge liquid transport pump P2, a test water transport pump P1, a liquid receiving injection pump P3, and a sample injection by capillary. A six-way valve V1 and a seven-way switching valve V2 are connected, and the gas-liquid separator is provided with a deep groove type ammonia discharge pool, and a ventilation film and a liquid receiving groove plate are provided above the ammonia discharge pool. Are laminated in order, and a capillary guide groove for the discharge liquid is provided on the inner bottom surface of the deep groove of the ammonia discharge pool, and an inlet connection pipe and an outlet connection pipe are respectively installed at both ends thereof. A liquid-receiving capillary groove having an inlet connecting pipe and an outlet connecting pipe installed at both ends thereof is provided, and the outlet connecting pipe communicates with the photoelectric colorimetric flow cell. A sampling loop S is connected between the connection port 2 and the connection port 5 of the hexagonal valve V1 for injection, and the connection port 4 is communicated with an inlet connection tube of a capillary groove for ammonia releasing liquid. 1 is an outlet for the waste water of the test water communicated with the transport pump P1, its connection port 6 is an inlet of the test water, its connection port 3 is connected to the connection port 5 of the seven-way valve V2, The connection port 1 of the valve V2 communicates with the inlet connection pipe for receiving liquid in the groove plate, the connection port 2 is connected to the injection pump P3, the connection port 3 is an inlet for receiving liquid, and the connection port 4 is The outlet 6 is connected to the outlet connecting pipe of the capillary groove of the carrier liquid in the ammonia releasing pool by the outlet liquid transport pump P2, and the connecting port 7 is the outlet of the waste liquid of the discharged liquid.

  For thin-film breathable membranes, it may be necessary to install a support plate between the upper part of the ammonia release pool and the vent membrane, and the support plate has through holes that match the capillary grooves of the liquid receiving in the groove plate. Provided. The support plate supports the gas permeable membrane and allows the rising ammonia gas to pass therethrough.

  In this apparatus, first, the test water is transported to the quantitative sampling loop S in the valve V1 by the pump P1, and the received liquid is injected into the receiving groove and the flow cell in the groove plate of the gas-liquid separator by the injection pump P3. The release liquid is transported to the discharge liquid capillary channel and to the capillary groove of the ammonia discharge pool by means of the transport by means of, and then the valve V1 is switched to connect the sampling loop to the discharge liquid flow path, and the valve V2 is switched to release the liquid. The capillary passage is formed in a loop, and the discharge liquid can be made to flow cyclically by the action of the pump P2. In this way, under the action of the pump P2, the sample water in the sampling loop forms one sample zone that circulates with the discharge liquid and continually diffuses into the discharge liquid and passes through the gas-liquid separator. In this case, a deep groove type gas rising groove that suddenly expands above the groove appears, whereby ammonia in the sample is released and rises, passes through the gas permeable membrane and is absorbed by the liquid receiving in the groove of the groove plate, After the acid-base indicator is discolored and the release of ammonia is completed, the injection pump is operated, and the discolored receiving liquid is transported to the flow cell, whereby the content of ammonia in the sample can be measured.

  Further improvements of the device are as follows.

  In order to prevent microbubbles that may be present in the receiving solution from interfering with photoelectric detection, the outlet end of the receiving tube's capillary groove extends through the through hole to the upper surface of the groove plate and faces upward. And the groove end is expanded into a wide groove, a ventilation film and a cover plate are combined on the groove plate, and the groove opening portion of the wide groove on the upper surface of the groove plate is formed on the lower surface of the cover plate. A gas collection groove is provided opposite to the gas collection groove, and an exhaust hole communicating with the atmosphere is provided in the gas collection groove. When the liquid receiver contains microbubbles, the microbubbles rise together with the liquid from the groove on the lower surface of the groove plate to the groove on the upper surface, and the air bubbles rise in the wide groove and permeate the gas permeable membrane laminated on the groove plate. Then, the gas rises to the gas collecting groove of the cover plate and is discharged to the atmosphere from the exhaust hole. Therefore, it is possible to prevent the phenomenon that affects the detection accuracy by the bubbles entering the photoelectric flow cell.

  In this apparatus, for convenience of measurement of the standard sample, 1 to 3 electromagnetic waves for conversion of the test water and the standard sample are connected to the connection port 6 of the sample injection valve V1 and the test water. A valve is provided. In this apparatus, the discharge pool in the gas-liquid separator is a deep groove type, and ammonia gas released from the groove at the bottom of the pool diffuses upward through the deep groove, and passes through the ventilation membrane to the liquid receiving system. Get in. The gas permeable membrane allows only gas, not water, to pass therethrough, further ensuring separation of ammonia gas and liquid. The deep groove keeps the gas permeable membrane away from the sample in the groove and avoids clogging the vent holes in the gas permeable membrane with impurities like pallets in the sample. This detection device can convert each valve based on a predetermined process by an automatic control system, and can realize automatic online detection for ammonia.

As described above, the present invention uses a flow injection analysis method (FIA) and a dedicated detection device, and by using sodium hydroxide as a release liquid and distilled water containing a weakly acidic acid-base indicator as a receiving liquid, NH ₃ Automatic online detection for -N, simple and rapid detection process, accurate and reliable detection data, only 50 μl to 1 ml of sample water injected for one detection, consumption The amount of reagent produced is extremely small, the running cost is low, the reagent is not toxic and does not discharge contaminants. Spectrophotometry with Nessler's reagent, salicylic acid-hypochlorite spectrophotometry, such as cumbersome operation, reagent toxic, or inability to store reagent for long periods of time, and high instrument price, and Overcoming drawbacks in methods such as ion chromatography.

It is a flowchart of the principle of the sampling state and circulation enrichment state of the colorimetric detection system of ammonia nitrogen by flow injection. It is a flowchart of the principle of the sampling state and circulation enrichment state of the colorimetric detection system of ammonia nitrogen by flow injection. It is a schematic diagram of the three-dimensional structure of a gas-liquid separator. It is a schematic diagram of the cross-sectional structure of a gas-liquid separator. It is sectional drawing by AA of FIG. It is sectional drawing by BB of FIG. It is a structure schematic diagram of the system flow of the colorimetric detection apparatus of ammonia nitrogen by flow injection. (1), (2) is a figure which shows the switching state of valve | bulb V1, V2 in FIG. 6, respectively. It is a structure schematic diagram of the system flow of the colorimetric detection device of ammonia nitrogen by flow injection including a standard sample measurement system.

  Hereinafter, the implementation flow and operation process of the colorimetric detection method for ammonia nitrogen by flow injection according to the present invention will be described based on FIG.

  The detection principle of ammonia nitrogen by this detection method is shown in FIGS. 1 (1) and 1 (2).

  FIGS. 1 (1) and 1 (2) both show that the upper part is a color-receiving liquid capillary channel system, the lower part is a discharge liquid capillary system, and both are connected by a gas-liquid separator.

  FIG. 1 (1) shows that the system is in the sampling state, and the receiving liquid is injected into the capillary tube by an injection pump and passes through the capillary groove at the top of the gas-liquid separator located above the ventilation membrane to the flow cell. Pass through and flow out of this flow cell to fill the upper capillary system and then stop the injection pump. On the other hand, the peristaltic pump causes a dilute solution of NaOH as a discharge liquid to flow through the lower pipeline system through the switching valve, to flow to the end in the direction of the arrow, and to discharge. The sample water is injected in the middle of the pipe line by an injection valve to form one sample zone.

Fig. 1 (2) shows that the system is in an enriched state, the lower pipe line becomes a system sealed by a switching valve, the discharge liquid flows cyclically, and the test water moves through the groove of the gas-liquid separator. When flowing through, the ammonia gas in the water rises through the deep groove, permeates through the gas permeable membrane and is received by the receiving liquid, and is enriched in the receiving liquid in which ammonia remains as the sample continuously circulates. The enlarged portion in the figure indicates that the lower sample zone is in a diffused state in the flowing discharge liquid, and ammonia (NH ₃ ) in the sample is released and rises to the gas permeable membrane. Get into the liquid. After the ammonia is appropriately enriched, the receiving liquid is pushed into the flow cell by an injection pump to perform photoelectric detection, and after obtaining a peak height curve, the ammonia content is calculated by conversion.

  2-5 shows the structure of embodiment concerning a gas-liquid separator.

  As shown in FIG. 2, the gas-liquid separator comprises, from bottom to top, an ammonia discharge pool 13 provided with an inlet connection pipe 11 and an outlet connection pipe 10 for the discharge liquid, a support plate 15, a gas permeable membrane 16, and a liquid receiver. The groove plate 17 provided with the inlet connection pipe 12 and the outlet connection pipe 14, the gas permeable membrane 16 ', and the cover plate 18 provided with the exhaust holes 19 are sequentially overlapped and connected.

  FIG. 3 shows the internal structure of the separator. A deep groove 23 is provided in the ammonia discharge pool 13, a capillary flow guide groove 24 (see FIG. 5) of the discharge liquid is provided on the bottom surface of the groove, the inlet connection pipe 11 is connected to one end of the groove, and the other end is connected to the outlet. It communicates with the tube 10. A support plate 15 for supporting the membrane is provided below the gas permeable membrane 16, and a through hole 25 is provided in the support plate. A liquid receiving groove 21 is provided on the lower surface of the groove plate 17, an exhaust groove 22 is provided on the upper surface thereof, and both grooves communicate with each other through a through hole 26. Between the groove plate 17 and the cover plate 18, a gas permeable membrane 16 ′ that matches the through hole 25 of the support plate 15 is provided.

  The separator is connected to the capillary line system of the discharged liquid by connecting pipes 11 and 10, and is connected to the capillary line system of the receiving liquid by connecting pipes 12 and 14. When the test water flows into the groove 24 from the inlet connecting pipe 11 together with the discharge liquid, ammonia gas is released upward from the groove 24, rises to the upper part of the deep groove 23, passes through the through hole 25 of the support plate 15, and the ventilation film 16. And then enters the liquid receiving groove 21 of the groove plate 17 and is received by the liquid receiving.

  If the received liquid contains fine bubbles, when the received liquid passes through the hole 26, the fine bubbles rise to the groove 22 and pass through the gas permeable membrane 16 'when passing through the gas permeable membrane below the gas collecting groove 20. The gas passes through the gas collecting groove 20 and is discharged from the exhaust hole 19 to the outside of the system.

  FIG. 6 shows the configuration of the system flow of the colorimetric detection device for ammonia nitrogen by flow injection. The operation process of ammonia nitrogen detection by the device will be described below with reference to FIG. is there.

[1. Washing]
a. V1 and V2 are switched to, for example, the states of V1B and V2B in FIG. 6, the peristaltic pump P2 is activated, and the discharged liquid is discharged liquid → V2 connection port 4 → connection port 5 → V1 connection port 3 → connection port 4 → Gas-liquid separator → Peristaltic pump P2 → Connection port 6 of V2 → Connection port 7 → Flow along the flow path of waste liquid bottle, and wash NH ₃ remaining in the separator for t1 second.

  b. By the time the injection pump P3 is activated and the photovoltage returns to the baseline, the received liquid is made to flow according to the flow path of injection pump → V2 connection port 2 → connection port 1 → gas-liquid separator → flow cell → waste liquid bottle, 20 seconds Maintain to finish washing.

[2. sampling]
c. V1 remains in the V1B state, V2 is switched to, for example, the state of V2A in FIG. 6 (2), P2 stops, P1 operates, and the test water is supplied from the test bottle → V1 connection port 6 → connection port 5 → connection. It is made to flow for 60 seconds according to the flow path of port 2-> connection port 1-> peristaltic pump P1-> waste bottle. The sample water filled the sampling loop S.

[3. Sample injection]
d. P1 stops, V1 remains in the state of V1B, V2 is switched to the state of V2B, P2 is activated, and the discharge liquid continues to flow for 10 seconds according to the flow path of step a. ) Is switched to the state of V1A, and P2 operates again for 25 seconds, and the flow path is discharged liquid → V2 connection port 4 → connection port 5 → V1 connection port 3 → connection port 2 → connection port 5 → connection port 4 → Gas-liquid separator → Peristaltic pump P2 → V2 connection port 6 → connection port 7 → waste liquid bottle, and sample water in the sampling loop S is injected in the middle of the discharge liquid flow.

[4. Circulation enrichment]
e. When V1 remains in the state of V1A and V2 is switched to the state of V2A in FIG. 6 (2), for example, the discharge liquid becomes a sealed system, the pump P2 continues to operate, and the discharge liquid pushes the test water to It is made to flow cyclically for t3 seconds like a flow path, the ammonia gas in a test water is discharge | released, and it enriches in a receiving liquid.
V1 port 3 → 2 → 5 → 4 → Gas-liquid separator
↑ ↓
V2 port 5 ← V2 port 6 ← Peristaltic pump P2

[5. Measurement]
f. P2 stops, and after t4 seconds, V1 remains in the state of V1A, V2 is switched to the V2B state, and the circulation ends. The injection pump P3 is activated, and according to the injection port P3 → V2 connection port 2 → connection port 1 → gas-liquid separator → flow cell → waste liquid bottle, the ammonia-absorbed liquid received in the gas-liquid separator is supplied to the photoelectric colorimetric flow cell. Push, measure the photovoltage, measure the baseline and peak, and calculate the ammonia content.

  FIG. 7 is a flow chart of an ammonia-nitrogen detection apparatus by flow injection including a standard sample measurement system, in which three solenoid valves V3, V4, and V5 are added to the system of FIG.

Example of detection of ammonia nitrogen [1. Preparation of reagents]
Preparation of release solution: 0.8 g of sodium hydroxide for analysis is weighed and dissolved in 100 ml of water, and water is added to the 1000 ml scale line and shaken uniformly. A NaOH solution having a concentration of 0.02 mol / l was prepared. Preparation of receiving solution: Weigh 50 mg of bromothymol blue, place in a small beaker, add 8 ml of absolute ethanol to dissolve, transfer to a bottle with a volume of 1000 ml, and add water to approach 1000 ml. Add 0.02 mol / l NaOH until pH = 6.7) and make up to 1000 ml with water.

  In addition, for ammonia nitrogen test water having a concentration higher than 200 mg / l, the pH of the receiver solution can be adjusted to about 6.2 (color is yellower than in the case of pH = 6.7).

  Preparation of standard samples: Two sets of standard samples were prepared, and the contents (mg / l) of ammonia nitrogen in the three standard samples for each set were as follows.

Set 1:
Standard sample 1: 50 mg / l, Standard sample 2: 70 mg / l, Standard sample 3: 100 mg / l

Set 2:
Standard sample 1: 800 mg / l, standard sample 2: 1000 mg / l, standard sample 3: 1200 mg / l.

[2. Experiment]
Ammonia is detected based on the operation steps such as washing, sampling, halfway injection of sample, circulation enrichment, and measurement.

(1) Sample 1
Measure the standard sample and sample 1 with reference to the standard sample of set 1 (enrichment time: 130 seconds, settling time: 25 seconds, number of washings: 5 times), and data are as shown in the table below is there.

(2) Sample 2
Measure the standard sample and sample 2 with reference to the standard sample of set 1 (enrichment time: 100 seconds, settling time: 5 seconds, number of washings: 12 times), and data are as shown in the table below It is.

  From the above two experiments, it can be seen that the ammonia nitrogen concentration of the sample measured by the method has a very small error compared to the actual concentration of the sample, which indicates that the detection accuracy is high.

10 (Discharged liquid) outlet connection pipe 11 (Discharged liquid) inlet connection pipe 12 (Received liquid) inlet connection pipe 13 Ammonia discharge pool 14 (Received liquid) outlet connection pipe 15 Support plates 16, 16 ′ Ventilation membrane 17 Groove plate 18 Cover plate 19 Exhaust hole 20 Gas collecting groove 21 Receiving groove (receiving liquid) Capillary groove 22 Exhausting groove 23 Deep groove 24 of discharge pool Capillary flow guide groove 25 Through hole 26 Through hole P1 Test water transport pump P2 Emission liquid Transport pump P3 Receiving injection pump V1 Six-way valve V2 Seven-way valve, Seven-way reverse valve

Claims (7)

A NaOH solution having a concentration of 0.01 mol / l to 0.03 mol / l is used as a release solution,
Injecting the release liquid into the capillary system to which a gas-liquid separator including a deep groove for preventing contact between the sample and the gas permeable membrane is connected,
A sample zone is formed by injecting a certain amount of sample water into the capillary passage having the discharge liquid;
By pumping, the sample zone flows cyclically in the capillary system with the discharge liquid, releasing ammonia gas as it passes through the deep groove of the gas-liquid separator,
This ammonia gas rises up to the groove opening, then permeates through the gas permeable membrane, is absorbed in the liquid containing the acid base indicator in the capillary groove on the other side of the gas permeable membrane, discolors the acid base indicator,
The sample zone is continuously circulated until the end of the release of the ammonia gas, the receiver solution in which the ammonia gas is absorbed is transferred to the flow cell of the colorimeter by an injection pump, and irradiated with light having a wavelength of 560 nm,
Measure the change in photovoltage when this light passes through the receiver, and calculate the concentration of ammonia nitrogen in the sample water by conversion.
This is a method for colorimetric detection of ammonia nitrogen by flow injection.   The method for colorimetric detection of ammonia nitrogen according to claim 1, wherein the acid-base indicator is bromothymol blue, and the receiving solution is a weakly acidic bromothymol blue solution.   A predetermined amount of the sample water is intermittently injected into a carrier liquid by a sample injection valve to form a plurality of sample zones intermittently distributed in a circulating capillary-gas-liquid separator flow path. The colorimetric detection method for ammonia nitrogen according to claim 1. A gas-liquid separator, a photoelectric detection flow cell, a discharge liquid transport pump (P2), a test water transport pump (P1), a liquid receiving injection pump (P3), and a six-way valve for sample injection (V1). And a seven-way reversing valve (V2)
The gas-liquid separator is provided with a deep groove type ammonia discharge pool (13),
On the upper part of the ammonia release pool, a gas permeable membrane (16) and a liquid receiving groove plate (17) are sequentially laminated,
On the inner bottom surface of the deep groove (23) of the ammonia discharge pool, there is provided a capillary flow guide groove (24) for the discharge liquid with an inlet connection pipe (11) and an outlet connection pipe (10) installed at both ends thereof,
On the lower surface of the groove plate (17), there is provided a liquid-receiving capillary groove (21) opened downward and having an inlet connection pipe (12) and an outlet connection pipe (14) installed at both ends thereof. ,
Among them, the outlet connection pipe (14) communicates with the photoelectric colorimetric flow cell, and a sampling loop (S) is connected between the connection port (2) and the connection port (5) in the six-way valve (V1), and sample injection The connection port (4) of the six-way valve (V1) for use is communicated with the inlet connection tube (11) of the capillary flow groove (24) for ammonia release liquid, and the connection port (1 of the hexagonal valve (V1)) ) Is the outlet of the waste water of the test water transported by the transport pump (P1), and the connection port (6) is the inlet of the test water,
The connection port (3) is connected to the connection port (5) of the seven-way valve (V2), and the connection port (1) of the seven-way valve (V2) is connected to the inlet of liquid receiving in the groove plate (17). The pipe (12) communicates, the connection port (2) is connected to the injection pump (P3), the connection port (3) of the seven-way valve (V2) is the connection port for the liquid receiver, and the connection port (4) is a connection port of the discharge liquid, and the connection port (6) communicates with the outlet connection pipe (10) of the capillary flow guide groove (24) of the discharge liquid by the discharge liquid transport pump (P2). The connection port 7 is an outlet of the waste liquid of the discharge liquid,
A colorimetric detection device for ammonia nitrogen by flow injection.   A support plate (15) is provided between the upper part of the ammonia release pool and the gas permeable membrane, and a through hole (25) that matches the capillary groove (21) of the liquid receiving in the groove plate (17) on the support plate. The colorimetric detection device according to claim 4, wherein:   The outlet end of the liquid-receiving capillary groove (21) passes through a through hole (26), extends to the upper surface of the groove plate (17), and becomes an exhaust groove (22) opened upward. The vent is expanded into a wide groove, a ventilation film (16 ′) and a cover plate (18) are laminated above the groove plate, and a wide groove on the upper surface of the groove plate (17) is formed on the lower surface of the cover plate (18). The gas collection groove (20) facing the groove opening portion of the gas collection groove is provided, and the gas collection groove (20) is provided with an exhaust hole (19) communicating with the atmosphere. The colorimetric detection device described.   One to three solenoid valves for converting the sample water and the standard sample are provided in the connection line between the connection port (6) of the hexagonal valve (V1) for sample injection and the sample water. The colorimetric detection device according to claim 4 or 5, wherein

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