CN108254370B - Testing device and method for quantitatively detecting nitrate content by direct sample introduction colorimetric method - Google Patents
Testing device and method for quantitatively detecting nitrate content by direct sample introduction colorimetric method Download PDFInfo
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- CN108254370B CN108254370B CN201810301309.2A CN201810301309A CN108254370B CN 108254370 B CN108254370 B CN 108254370B CN 201810301309 A CN201810301309 A CN 201810301309A CN 108254370 B CN108254370 B CN 108254370B
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- 229910002651 NO3 Inorganic materials 0.000 title claims abstract description 109
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 title claims abstract description 96
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000012360 testing method Methods 0.000 title claims abstract description 16
- 238000004737 colorimetric analysis Methods 0.000 title abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims abstract description 66
- LNOPIUAQISRISI-UHFFFAOYSA-N n'-hydroxy-2-propan-2-ylsulfonylethanimidamide Chemical compound CC(C)S(=O)(=O)CC(N)=NO LNOPIUAQISRISI-UHFFFAOYSA-N 0.000 claims abstract description 45
- -1 nitrite ions Chemical class 0.000 claims abstract description 45
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 39
- 229920006254 polymer film Polymers 0.000 claims abstract description 13
- 239000007788 liquid Substances 0.000 claims abstract description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 156
- 239000000243 solution Substances 0.000 claims description 85
- 238000005086 pumping Methods 0.000 claims description 34
- 238000000502 dialysis Methods 0.000 claims description 29
- 230000002572 peristaltic effect Effects 0.000 claims description 14
- 239000000385 dialysis solution Substances 0.000 claims description 13
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims description 11
- 238000011161 development Methods 0.000 claims description 9
- 229920005597 polymer membrane Polymers 0.000 claims description 7
- 239000002699 waste material Substances 0.000 claims description 7
- 238000004891 communication Methods 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 5
- 239000011148 porous material Substances 0.000 claims description 4
- 239000004743 Polypropylene Substances 0.000 claims description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- 229940005654 nitrite ion Drugs 0.000 claims description 3
- 229920001155 polypropylene Polymers 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 238000001228 spectrum Methods 0.000 claims description 3
- 238000001514 detection method Methods 0.000 abstract description 11
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 10
- 238000009792 diffusion process Methods 0.000 abstract description 6
- 238000004364 calculation method Methods 0.000 abstract description 5
- 239000012466 permeate Substances 0.000 abstract description 4
- 239000007864 aqueous solution Substances 0.000 description 12
- FUSNOPLQVRUIIM-UHFFFAOYSA-N 4-amino-2-(4,4-dimethyl-2-oxoimidazolidin-1-yl)-n-[3-(trifluoromethyl)phenyl]pyrimidine-5-carboxamide Chemical group O=C1NC(C)(C)CN1C(N=C1N)=NC=C1C(=O)NC1=CC=CC(C(F)(F)F)=C1 FUSNOPLQVRUIIM-UHFFFAOYSA-N 0.000 description 5
- 229910000365 copper sulfate Inorganic materials 0.000 description 5
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 5
- 239000012493 hydrazine sulfate Substances 0.000 description 5
- 229910000377 hydrazine sulfate Inorganic materials 0.000 description 5
- 239000011259 mixed solution Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000005206 flow analysis Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000007924 injection Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 2
- 231100000572 poisoning Toxicity 0.000 description 2
- 230000000607 poisoning effect Effects 0.000 description 2
- 239000012086 standard solution Substances 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 210000001035 gastrointestinal tract Anatomy 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
-
- 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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- General Health & Medical Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Chemical Kinetics & Catalysis (AREA)
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- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention provides a testing device for quantitatively detecting nitrate content by direct sample introduction colorimetric method, and belongs to the field of nitrate content detection. According to the invention, the sulfamic acid inlet is arranged in the mixing system, so that nitrite ions (NO 2 ‑) in a sample can be removed, the sample can be divided into a plurality of sections by the air inlet to prevent diffusion, the polymer film allows the nitrate ions (NO 3 ‑) to permeate into the lower-layer groove, liquid containing the nitrate ions in the lower-layer groove is mixed with the reducing agent, the nitrate ions (NO 3 ‑) are reduced into nitrite ions by the reducing agent, and finally the NO 2 ‑ enters the flow-through cuvette after the subsequent chemical reaction module continues to react and develop, and the flow-through cuvette is measured and calculated by the detector. The end result is the nitrate value. The invention obtains the detection result once, saves the trouble of manual calculation, reduces the workload by one time compared with the prior art, and does not need to replace the reagent in the detection process.
Description
Technical Field
The invention relates to the technical field of nitrate content detection, in particular to a device and a method for detecting nitrate content by a direct sample introduction colorimetric method.
Background
Nitrate is the most stable nitride in various nitrogen-containing compounds such as nitrite, ammonia nitrogen and the like in an aerobic environment, and is also the final decomposition product of nitrogen-containing organic matters through inorganic conversion. After the human body intakes nitrate, the nitrate is converted into nitrite by the action of microorganisms in intestinal tracts, and poisoning phenomenon occurs. It is reported in literature that when nitrate content in water reaches tens of milligrams per liter, infant poisoning can be caused.
In recent years, a continuous flow analysis technology is introduced in China, and the equipment can continuously and automatically mix a large number of samples, automatically add a color reagent, automatically compare colors and automatically calculate results, so that the manual workload is greatly reduced. The principle of the automatic equipment is that a peristaltic pump pumps a sample and a specific reagent into a mixing ring, and meanwhile, air bubbles are uniformly added to divide the mixed solution of the sample and the specific reagent into a plurality of sections to prevent diffusion, the mixed solution flows through a dialysis device with a polymer membrane after being uniformly mixed, impurities are filtered by the polymer membrane, and the liquid containing components to be detected reacts with the specific reagent to develop color and then enters a flow-through cuvette, and the liquid is measured and calculated by a detector. Finally, the nitrate value is obtained through manual calculation.
However, when nitrate is detected by the current continuous flow analysis equipment, nitrate cannot be directly detected, and the solution needs to obtain the result of nitrate through three steps: the method comprises the steps of firstly, measuring the sum value of nitrate and nitrite contained in a sample, secondly, measuring the value of nitrite contained in the sample, thirdly, subtracting the value of nitrite from the sum value of nitrate and nitrite, and finally obtaining the value of nitrate. The continuous flow analysis equipment disclosed by the prior art has complex analysis steps and large workload, and can not directly obtain the quantitative detection result of nitrate.
Disclosure of Invention
The invention aims to provide a testing device and method for quantitatively detecting nitrate content by direct sample introduction colorimetric method. The testing device for quantitatively detecting the nitrate content by the direct sample introduction colorimetric method of the nitric acid provided by the invention can obtain the nitrate detection result at one time, so that the workload is greatly reduced, the trouble of manual calculation is eliminated, and the testing device is simple, convenient and quick.
The invention provides a testing device for quantitatively detecting nitrate content by direct sample introduction colorimetric method, which comprises a mixing system (1), a first feeding system (2), a dialysis system (3), a chemical reaction system (4) and a detector (5) which are sequentially communicated; also comprises a second feeding system (6);
The mixing system (1) is provided with a first air inlet (101), a first sample inlet (102) and a sulfamic acid inlet (103);
The first feeding system (2) is provided with a second air inlet (201), a first sodium hydroxide inlet (202) and a second sample inlet (203), and the outlet of the mixing system (1) is communicated with the second sample inlet (203);
The dialysis system (3) comprises an upper U-shaped groove (301) and a lower U-shaped groove (302) which are mirror images of each other and a polymer film (303) clamped between the two U-shaped grooves, wherein the upper port of the upper U-shaped groove (301) is communicated with the outlet of the first feeding system (2), the lower port (304) of the upper U-shaped groove (301) is a waste liquid outlet, the upper port of the lower U-shaped groove (302) is communicated with the outlet of the second feeding system (6), and the second feeding system (6) is provided with a third air inlet (601) and a second sodium hydroxide inlet (602);
The lower port of the lower U-shaped groove (302) is a dialysis device outlet and is communicated with the feed inlet of the chemical reaction system (4); a reducing agent inlet (7) is also arranged on a pipeline between the outlet of the lower U-shaped groove (302) and the chemical reaction system (4);
and a discharge port of the chemical reaction system (4) is communicated with a sample inlet of the detector (5).
Preferably, the polymer film is a polypropylene film.
Preferably, the pore size of the polymer membrane is 0.2 to 0.8 μm.
Preferably, the detector is a CCD full spectrum direct-reading detector or a silicon photocell detector.
Preferably, a peristaltic pump is also included in communication with the reductant inlet for pumping the reductant into the tube.
Preferably, a peristaltic pump is further arranged, and a first air outlet, a second air outlet and a third air outlet are respectively arranged on the peristaltic pump and are respectively communicated with the first air inlet, the second air inlet and the third air inlet.
The invention also provides a method for quantitatively detecting the nitrate content by the testing device according to the technical scheme, which comprises the following steps:
(1) The nitrate-containing solution to be measured flows through a mixing system through a first sample inlet, sulfamic acid through a sulfamic acid inlet and air through a first air inlet to obtain nitrate solution for removing nitrite ions;
(2) Enabling the nitrate solution with nitrite ions removed obtained in the step (1) to flow through a first feeding system through a second sample inlet, air through a second air inlet and sodium hydroxide through a first sodium hydroxide inlet to obtain a pre-dialyzed nitrate solution;
(3) Leading the pre-dialyzed nitrate solution obtained in the step (2) to enter a dialysis module from an upper port of the upper U-shaped groove, and enabling air to flow through the upper U-shaped groove from a third air inlet and sodium hydroxide from a second sodium hydroxide inlet to obtain a dialysis solution;
(4) Enabling the dialysis solution obtained in the step (3) to flow out from the lower end outlet of the lower U-shaped groove and enter the chemical reaction system through the feed inlet of the chemical reaction system, and enabling the reducing agent to enter the chemical reaction system through the pipeline between the lower end outlet of the lower U-shaped groove and the chemical reaction system through the reducing agent inlet to perform color development reaction to obtain color development solution;
(5) And (3) enabling the chromogenic solution obtained in the step (4) to flow through a detector, and monitoring to obtain the nitrate content in the nitrate-containing solution.
Preferably, the mass ratio of sulfamic acid to nitrite ion in the step (1) is 280-630:1.
Preferably, the sulfamic acid is pumped in the form of an aqueous sulfamic acid solution, the pumping speed of the aqueous sulfamic acid solution is 10-15 r/min, and the concentration of the aqueous sulfamic acid solution is 0.03-1%.
Preferably, the air pump speeds of the first air inlet, the second air inlet and the third air inlet are independently 10-15 r/min.
Compared with the prior art, the invention has the following technical effects:
The invention provides a testing device for quantitatively detecting nitrate content by a direct sample-injection colorimetric method, which comprises a mixing system, a first feeding system, a dialysis system, a chemical reaction system and a detector which are sequentially communicated; the mixing system is provided with a first air inlet, a first sample inlet and a sulfamic acid inlet; the first feeding system is provided with a second air inlet, a first sodium hydroxide inlet and a second sample inlet, and the outlet of the mixing system is communicated with the second sample inlet; the dialysis system comprises an upper U-shaped groove, a lower U-shaped groove and a polymer film, wherein the upper U-shaped groove and the lower U-shaped groove are mirror images of each other, the polymer film is clamped between the two U-shaped grooves, the upper port of the upper U-shaped groove is communicated with the outlet of the first feeding system, the lower port of the upper U-shaped groove is a waste liquid outlet, the upper port of the lower U-shaped groove is communicated with the outlet of the second feeding system, and the second feeding system is provided with a third air inlet and a second sodium hydroxide inlet; the lower port of the lower U-shaped groove is a dialysis device outlet and is communicated with a feed inlet of the chemical reaction system; a reducing agent inlet is also arranged on a pipeline between the outlet of the lower U-shaped groove and the chemical reaction system; and a discharge port of the chemical reaction system is communicated with a sample inlet of the detector. According to the invention, the sulfamic acid inlet is arranged in the mixing system, so that nitrite ions (NO 2 -) in a sample can be removed, the sample can be divided into a plurality of sections by the air inlet to prevent diffusion, a polymer film allows molecules with small molecular weight, such as nitrate ions (NO 3 -), to permeate into a lower groove, other impurities flow out from the other end of an upper groove, liquid containing nitrate ions (NO 3 -) in the lower groove is mixed with a reducing agent, nitrate ions (NO 3 -) are reduced into nitrite ions (NO 2 -) by the reducing agent, finally nitrite ions (NO 2 -) enter a flow-through cuvette after a subsequent chemical reaction module continues to react and develop, and the measuring and calculating result is the nitrate value by a detector. The invention obtains the detection result once, saves the trouble of manual calculation, reduces the workload by one time compared with the prior art, and does not need to replace the reagent in the detection process.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a testing device for quantitatively detecting nitrate content by a direct sample colorimetric method according to an embodiment of the present invention;
In the figure, 1 is a mixing system, 2 is a first feeding system, 3 is a dialysis system, 4 is a chemical reaction system, 5 is a detector, 101 is a first air inlet, 102 is a first sample inlet, 103 is a sulfamic acid inlet, 201 is a second air inlet, 202 is a first sodium hydroxide inlet, 203 is a second sample inlet, 301 is an upper U-shaped groove, 302 is a lower U-shaped groove, 303 is a polymer film sandwiched between the two U-shaped grooves, 304 is a waste liquid outlet, 6 is a second feeding system, 601 is a third air inlet, 602 is a second sodium hydroxide inlet, 7 is a reducing agent inlet, and a vertical line which can rotate in the figure represents a peristaltic pump, and an arrow thereof represents the rotation direction of the peristaltic pump;
fig. 2 is a schematic diagram of a dialysis apparatus.
Detailed Description
As shown in FIG. 1, the testing device for quantitatively detecting the nitrate content by the direct sample colorimetric method provided by the invention comprises a mixing system 1, a first feeding system 2, a dialysis system 3, a chemical reaction system 4 and a detector 5 which are sequentially communicated;
The mixing system 1 is provided with a first air inlet 101, a first sample inlet 102 and a sulfamic acid inlet 103;
The first feeding system 2 is provided with a second air inlet 201, a first sodium hydroxide inlet 202 and a second sample inlet 203, and the outlet of the mixing system is communicated with the second sample inlet;
the dialysis system 3 comprises an upper U-shaped groove 301 and a lower U-shaped groove 302 which are mirror images of each other and a polymer film 303 clamped between the two U-shaped grooves, wherein the upper port of the upper U-shaped groove 301 is communicated with the outlet of the first feeding system, the lower port of the upper U-shaped groove 302 is a waste liquid outlet 304, the upper port of the lower U-shaped groove is communicated with the outlet of the second feeding system 6, and the second feeding system is provided with a third air inlet 601 and a second sodium hydroxide inlet 602;
The lower port of the lower U-shaped groove 302 is a dialysis device outlet and is communicated with the feed inlet of the chemical reaction system 4; a reducing agent inlet 7 is also arranged on a pipeline between the outlet of the lower U-shaped groove and the chemical reaction system;
The discharge port of the chemical reaction system 4 is communicated with the sample inlet of the detector 5.
The method for communicating all the components in the test device for quantitatively detecting the nitrate content by the direct sample colorimetric method is not particularly limited, and the method can be carried out by adopting pipeline communication well known to a person skilled in the art.
As shown in fig. 1, the testing device for quantitatively detecting the nitrate content by the direct sample colorimetric method sequentially comprises a mixing system 1, a first feeding system 2, a dialysis system 3, a chemical reaction system 4 and a detector 5, wherein a rotatable vertical line in the figure represents a peristaltic pump, and an arrow thereof represents the rotation direction of the peristaltic pump. In the invention, the sulfamic acid inlet 103 is arranged in the mixing system, nitrite ions (NO 2 -) in the sample can be removed, the air inlet can divide the sample into a plurality of sections to prevent diffusion, the polymer film allows molecules with small molecular weight, such as nitrate ions (NO 3 -), to permeate into the lower groove, other impurities flow out from the other end of the upper groove, liquid containing nitrate ions (NO 3 -) in the lower groove is mixed with a reducing agent, nitrate ions (NO 3 -) are reduced into nitrite ions (NO 2 -) by the reducing agent, finally nitrite ions (NO 2 -) enter the flow-through cuvette after the subsequent chemical reaction module continues to react and develop, the measuring and calculating are carried out by the detector, and the final result is the value of nitrate. The invention obtains the detection result once, saves the trouble of manual calculation, reduces the workload by one time compared with the prior art, and does not need to replace the reagent in the detection process.
In the present invention, the mixing system 1 is provided with a first air inlet 101, a first sample inlet 102 and a sulfamic acid inlet 103. In the present invention, the sulfamic acid inlet is capable of removing nitrite ions (NO 2-) from the sample. In the invention, the first air inlet can divide the sample to be tested into a plurality of sections to prevent diffusion. In the present invention, a peristaltic pump is also included in communication with the sulfamic acid inlet for pumping the sulfamic acid aqueous solution into the tubing. In the present invention, the sulfamic acid is preferably pumped as an aqueous sulfamic acid solution, the pumping speed of the aqueous sulfamic acid solution is preferably 10 to 15r/min, and the concentration of the aqueous sulfamic acid solution is preferably 0.03 to 1%.
In the invention, the first sodium hydroxide inlet is to pump the first sodium hydroxide into the pipeline, because the sulfamic acid aqueous solution is acidic, the mixed solution with acidity needs to be neutralized after the reaction of the sample and the sulfamic acid is finished, otherwise, H + in the mixed solution can permeate the polymer membrane to slow down the reduction efficiency of the reducing agent (the reducing agent needs to react under alkaline conditions).
In the present invention, the outlet of the mixing system 1 is provided with a waste liquid outlet, and the mixing system 1 generates gas during the reaction, which may disturb the air bubbles that are regularly injected into the first air inlet 101, and the disordered air bubbles enter the first feeding system 2, which may disturb the subsequent reaction, so that the air bubbles in the mixing system 1 need to be removed after the reaction.
In the present invention, the first feeding system 2 is provided with a second air inlet 201, a first sodium hydroxide inlet 202 and a second sample inlet 203, and the outlet of the mixing system is communicated with the second sample inlet. In the invention, the second air inlet can divide the sample to be tested into a plurality of sections to prevent diffusion.
In the present invention, the dialysis system 3 comprises an upper U-shaped groove 301 and a lower U-shaped groove 302 which are mirror images of each other, and a polymer membrane 303 sandwiched between the two U-shaped grooves, wherein the upper port of the upper U-shaped groove 301 is communicated with the outlet of the first feeding system, the lower port of the upper U-shaped groove 302 is a waste liquid outlet 304, the upper port of the lower U-shaped groove is communicated with the outlet of the second feeding system 6, and the second feeding system is provided with a third air inlet 601 and a second sodium hydroxide inlet 602. In the present invention, the lower port of the lower U-shaped groove 302 is a dialysis device outlet, and is communicated with the feed inlet of the chemical reaction system 4; and a reducing agent inlet 7 is also arranged on a pipeline between the outlet of the lower U-shaped groove and the chemical reaction system. In the present invention, the polymer film is a polypropylene film. In the present invention, the pore diameter of the polymer film is preferably 0.2 to 0.8. Mu.m.
In the present invention, a peristaltic pump is also included in communication with the reductant inlet for pumping the reductant into the tube.
In the present invention, a peristaltic pump is preferably further provided, and the peristaltic pump is preferably provided with a first air outlet, a second air outlet and a third air outlet, which are respectively communicated with the first air inlet, the second air inlet and the third air inlet.
In the invention, the discharge port of the chemical reaction system 4 is communicated with the sample inlet of the detector 5. In the present invention, nitrite ions in the chemical reaction system 4 undergo a color reaction. In the present invention, the detector is preferably a CCD full spectrum direct-reading detector or a silicon photocell detector.
In the present invention, the chemical reaction system includes a color reaction reagent capable of reacting with nitrate ions. The color reagent used in the color reaction of the chemical reaction system, the time and temperature of the color reaction are not particularly limited, and may be any one known to those skilled in the art.
In the present invention, the air is preferably pumped in, and the air is preferably introduced through a unified pipe.
The invention also provides a method for quantitatively detecting the nitrate content by the testing device according to the technical scheme, which comprises the following steps:
(1) The nitrate-containing solution to be measured flows through a mixing system through a first sample inlet, sulfamic acid through a sulfamic acid inlet and air through a first air inlet to obtain nitrate solution for removing nitrite ions;
(2) Enabling the nitrate solution with nitrite ions removed obtained in the step (1) to flow through a first feeding system through a second sample inlet, air through a second air inlet and sodium hydroxide through a first sodium hydroxide inlet to obtain a pre-dialyzed nitrate solution;
(3) Leading the pre-dialyzed nitrate solution obtained in the step (2) to enter a dialysis module from an upper port of the upper U-shaped groove, and enabling air to flow through the upper U-shaped groove from a third air inlet and sodium hydroxide from a second sodium hydroxide inlet to obtain a dialysis solution;
(4) Enabling the dialysis solution obtained in the step (3) to flow out from the lower end outlet of the lower U-shaped groove and enter the chemical reaction system through the feed inlet of the chemical reaction system, and enabling the reducing agent to enter the chemical reaction system through the pipeline between the lower end outlet of the lower U-shaped groove and the chemical reaction system through the reducing agent inlet to perform color development reaction to obtain color development solution;
(5) And (3) enabling the chromogenic solution obtained in the step (4) to flow through a detector, and monitoring to obtain the nitrate content in the nitrate-containing solution.
According to the invention, nitrate-containing solution to be measured flows through a mixing system from a first air inlet through a first sample inlet, sulfamic acid through a sulfamic acid inlet and air to obtain nitrate solution for removing nitrite ions. In the present invention, the mass ratio of sulfamic acid to nitrite ion is preferably 280 to 630:1.
In the present invention, the sulfamic acid is preferably pumped as an aqueous sulfamic acid solution, the pumping speed of the aqueous sulfamic acid solution is preferably 10 to 15r/min, and the concentration of the aqueous sulfamic acid solution is preferably 0.03 to 1%.
In the invention, the concentration of nitrite ions in the nitrate-containing solution to be measured is preferably 3-20 mg/L. The method has no special limitation on the concentration of nitrate in the nitrate-containing solution to be measured, has no special limitation on the source of the nitrate-containing solution to be measured, and can be suitable for groundwater, surface water, industrial wastewater, domestic sewage and the like.
In the present invention, the nitrate-containing solution is preferably pumped into the first sample inlet, and the pumping speed of the nitrate-containing solution is preferably 10-15 r/min.
In the present invention, the air flow rate of the first air inlet is preferably 10 to 15r/min.
After the nitrate solution for removing nitrite ions is obtained, the obtained nitrate solution for removing nitrite ions flows through a first feeding system through a second sample inlet, air flows through a second air inlet and sodium hydroxide flows through a first sodium hydroxide inlet to obtain a pre-dialyzed nitrate solution.
In the present invention, the nitrite ion-removing nitrate solution is preferably pumped into the second sample inlet, and the pumping speed of the nitrite ion-removing nitrate solution is preferably 10-15 r/min.
In the present invention, the air flow rate of the second air inlet is preferably 10 to 15r/min.
In the present invention, the sodium hydroxide is preferably pumped into the first sodium hydroxide inlet in the form of an aqueous sodium hydroxide solution. In the present invention, the concentration of the aqueous sodium hydroxide solution is preferably 0.1 to 1mol/L. In the present invention, the pumping speed of the aqueous sodium hydroxide solution is preferably 10 to 15r/min. Acid-base neutralization reaction can occur in the first sample injection system, so as to remove H + in the mixed solution.
After the pre-dialysis nitrate solution is obtained, the pre-dialysis nitrate solution enters the dialysis module from the upper port of the upper U-shaped groove, and air flows through the upper U-shaped groove from the third air inlet and sodium hydroxide from the second sodium hydroxide inlet to obtain the dialysis solution.
The schematic diagram of the dialysis apparatus is shown in fig. 2, wherein the upper and lower layers are separated by a polymer membrane having a microporous pore structure through which small molecules or ions can pass.
In the invention, the pre-dialysis nitrate solution is preferably pumped into the upper port of the upper U-shaped groove, and the pumping speed of the pre-dialysis nitrate solution is preferably 10-15 r/min.
In the invention, the air pump speed of the third air inlet is preferably 10-15 r/min.
In the present invention, the sodium hydroxide is preferably pumped into the second sodium hydroxide inlet in the form of an aqueous sodium hydroxide solution. In the present invention, the concentration of the aqueous sodium hydroxide solution is preferably 0.1 to 1mol/L. In the present invention, the pumping speed of the aqueous sodium hydroxide solution is preferably 10 to 15r/min.
After the dialysis solution is obtained, the dialysis solution flows out from the lower end outlet of the lower U-shaped groove and enters the chemical reaction system through the feed inlet of the chemical reaction system to carry out a color reaction, the color development solution is obtained, and the reducing agent enters a pipeline between the lower end outlet of the lower U-shaped groove and the chemical reaction system through the reducing agent inlet.
In the present invention, the reducing agent is preferably hydrazine sulfate and copper sulfate. In the present invention, the reducing agent is preferably pumped into the pipeline in the form of an aqueous reducing agent solution. In the invention, the pumping speed of the aqueous solution of the reducing agent is preferably 10-15 r/min, and the concentration of the aqueous solution of the reducing agent is preferably hydrazine sulfate: 0.005mol/L, copper sulfate: 2X 10 -5 mol/L, more preferably hydrazine sulfate: 0.03mol/L, copper sulfate: 9.2X10 -5 mol/L.
The color reagent used in the color reaction of the chemical reaction system, the time and temperature of the color reaction are not particularly limited, and may be any one known to those skilled in the art.
After the color developing solution is obtained, the color developing solution flows through a detector, and the nitrate content in the nitrate-containing solution is obtained through monitoring.
The principle is briefly described as follows:
Preparing a nitrate standard solution sequence (calculated by nitrate ions) with gradient concentration of 0-Xmg/L, detecting the standard solution with the gradient concentration by using the system, drawing a standard curve by the equipment, bringing the absorbance value of a sample to be detected by the equipment into the standard curve, and calculating the concentration value (calculated by nitrate ions) of nitrate contained in the sample to be detected.
In order to further illustrate the present invention, the test device and method for quantitative detection of nitrate content by direct sample colorimetric method provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1:
(1) The nitrate-containing solution to be measured flows through a mixing system through a first sample inlet, sulfamic acid through a sulfamic acid inlet and air through a first air inlet to obtain nitrate solution for removing nitrite ions, wherein the concentration of nitrite ions in the nitrate-containing solution is 4mg/L, the concentration of nitrate ions is 6mg/L, the pumping speed is 15r/min, the pumping speed of sulfamic acid aqueous solution (the concentration is 0.03%) is 15r/min, and the pumping speed of air is 15r/min;
(2) Enabling the nitrate solution with nitrite ions removed obtained in the step (1) to flow through a first feeding system through a second sample inlet, air through a second air inlet and sodium hydroxide through a first sodium hydroxide inlet to obtain a pre-dialyzed nitrate solution, wherein the pumping speed of the nitrate solution with nitrite ions removed is 15r/min, the pumping speed of air is 15r/min, and the pumping speed of sodium hydroxide aqueous solution (with concentration of 1 mol/L) is 15r/min;
(3) Leading the pre-dialyzed nitrate solution obtained in the step (2) to enter a dialysis module from an upper port of an upper U-shaped groove, enabling air to flow through the upper U-shaped groove from a third air inlet and sodium hydroxide from a second sodium hydroxide inlet to obtain a dialysis solution, wherein the pumping speed of the pre-dialyzed nitrate solution is 15r/min, the pumping speed of air is 15r/min, and the pumping speed of sodium hydroxide aqueous solution (with the concentration of 1 mol/L) is 15r/min;
(4) Enabling the dialysis solution obtained in the step (3) to flow out from the lower end outlet of the lower U-shaped groove and enter a chemical reaction system through a feed inlet of the chemical reaction system to carry out a color reaction to obtain a color development solution, enabling a reducing agent to enter a pipeline between the lower end outlet of the lower U-shaped groove and the chemical reaction system through a reducing agent inlet, and enabling the pumping speed of a reducing agent aqueous solution (hydrazine sulfate: 0.03mol/L and copper sulfate: 9.2X10 -5 mol/L) to be 15r/min;
(5) And (3) allowing the chromogenic solution obtained in the step (4) to flow through a detector, and detecting to obtain the nitrate content in the nitrate-containing solution which is 6.01mg/L.
Example 2:
(1) The nitrate-containing solution to be measured flows through a mixing system through a first sample inlet, sulfamic acid through a sulfamic acid inlet and air through a first air inlet to obtain nitrate solution for removing nitrite ions, wherein the concentration of nitrite ions in the nitrate-containing solution is 10mg/L, the concentration of nitrate ions is 3mg/L, the pumping speed is 15r/min, the pumping speed of sulfamic acid aqueous solution (the concentration is 0.03%) is 15r/min, and the pumping speed of air is 15r/min;
(2) Enabling the nitrate solution with nitrite ions removed obtained in the step (1) to flow through a first feeding system through a second sample inlet, air through a second air inlet and sodium hydroxide through a first sodium hydroxide inlet to obtain a pre-dialyzed nitrate solution, wherein the pumping speed of the nitrate solution with nitrite ions removed is 15r/min, the pumping speed of air is 15r/min, and the pumping speed of sodium hydroxide aqueous solution (with concentration of 1 mol/L) is 15r/min;
(3) Leading the pre-dialyzed nitrate solution obtained in the step (2) to enter a dialysis module from an upper port of an upper U-shaped groove, enabling air to flow through the upper U-shaped groove from a third air inlet and sodium hydroxide from a second sodium hydroxide inlet to obtain a dialysis solution, wherein the pumping speed of the pre-dialyzed nitrate solution is 15r/min, the pumping speed of air is 15r/min, and the pumping speed of sodium hydroxide aqueous solution (with the concentration of 1 mol/L) is 15r/min;
(4) Enabling the dialysis solution obtained in the step (3) to flow out from the lower end outlet of the lower U-shaped groove and enter a chemical reaction system through a feed inlet of the chemical reaction system to carry out a color reaction to obtain a color development solution, enabling a reducing agent to enter a pipeline between the lower end outlet of the lower U-shaped groove and the chemical reaction system through a reducing agent inlet, and enabling the pumping speed of a reducing agent aqueous solution (hydrazine sulfate: 0.03mol/L and copper sulfate: 9.2X10 -5 mol/L) to be 15r/min;
(5) And (3) enabling the chromogenic solution obtained in the step (4) to flow through a detector, and monitoring to obtain the nitrate content in the nitrate-containing solution to be 3.98mg/L.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be comprehended within the scope of the present invention.
Claims (9)
1. A method for quantitatively detecting nitrate content, comprising the steps of:
Step (1), enabling a nitrate-containing solution to be tested to flow through a mixing system through a first sample inlet, sulfamic acid through a sulfamic acid inlet and air through a first air inlet to obtain a nitrate solution for removing nitrite ions;
Step (2) enabling the nitrate solution with nitrite ions removed obtained in the step (1) to flow through a first feeding system through a second sample inlet, air through a second air inlet and sodium hydroxide through a first sodium hydroxide inlet to obtain a pre-dialyzed nitrate solution;
Step (3), enabling the pre-dialyzed nitrate solution obtained in the step (2) to enter a dialysis module from an upper port of the upper U-shaped groove, and enabling air to flow through the upper U-shaped groove from a third air inlet and sodium hydroxide from a second sodium hydroxide inlet to obtain a dialysis solution;
Step (4) enabling the dialysis solution obtained in the step (3) to flow out from the lower end outlet of the lower U-shaped groove and enter the chemical reaction system through the feed inlet of the chemical reaction system, and enabling the reducing agent to enter the chemical reaction system through the pipeline between the lower end outlet of the lower U-shaped groove and the chemical reaction system through the reducing agent inlet, so as to perform color development reaction and obtain color development solution;
Step (5), enabling the chromogenic solution obtained in the step (4) to flow through a detector, and monitoring to obtain the nitrate content in the nitrate-containing solution;
the testing device used by the method comprises a mixing system (1), a first feeding system (2), a dialysis system (3), a chemical reaction system (4) and a detector (5) which are sequentially communicated; also comprises a second feeding system (6);
the mixing system (1) is provided with a first air inlet (101), a first sample inlet (102) and a sulfamic acid inlet (103);
The first feeding system (2) is provided with a second air inlet (201), a first sodium hydroxide inlet (202) and a second sample inlet (203), and the outlet of the mixing system (1) is communicated with the second sample inlet (203);
The dialysis system (3) comprises an upper U-shaped groove (301) and a lower U-shaped groove (302) which are mirror images of each other and a polymer film (303) clamped between the two U-shaped grooves, wherein the upper port of the upper U-shaped groove (301) is communicated with the outlet of the first feeding system (2), the lower port (304) of the upper U-shaped groove (301) is a waste liquid outlet, the upper port of the lower U-shaped groove (302) is communicated with the outlet of the second feeding system (6), and the second feeding system (6) is provided with a third air inlet (601) and a second sodium hydroxide inlet (602);
The lower port of the lower U-shaped groove (302) is a dialysis device outlet and is communicated with the feed inlet of the chemical reaction system (4); a reducing agent inlet (7) is also arranged on a pipeline between the outlet of the lower U-shaped groove (302) and the chemical reaction system (4);
and a discharge port of the chemical reaction system (4) is communicated with a sample inlet of the detector (5).
2. The method of claim 1, wherein the mass ratio of sulfamic acid to nitrite ion in step (1) is 280-630:1.
3. The method according to claim 2, wherein the sulfamic acid is pumped as an aqueous sulfamic acid solution at a pumping rate of 10 to 15r/min and at a concentration of 0.03 to 1%.
4. The method of claim 1, wherein the air pump speeds of the first, second and third air inlets are independently 10-15 r/min.
5. The method of claim 1, wherein the polymer film is a polypropylene film.
6. The method according to claim 1 or 5, wherein the polymer membrane has a pore size of 0.2 to 0.8 μm.
7. The method of claim 1, wherein the detector is a CCD full spectrum direct-reading detector or a silicon photocell detector.
8. The method of claim 1, further comprising a peristaltic pump in communication with the reductant inlet for pumping the reductant into a tube.
9. The method of claim 1, further comprising providing peristaltic pumps having first, second and third air outlets, respectively, in communication with the first, second and third air inlets, respectively.
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