CN115979978A - Method for measuring ammonia nitrogen content of mariculture water body - Google Patents
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Abstract
The invention discloses a method for measuring the ammonia nitrogen content of a mariculture water body, which comprises the steps of taking the mariculture water body as a sample to be measured, filtering and measuring the salinity of the sample to be measured; preparing ammonia nitrogen stock solution, blank solution, standard solution, sample solution and reagents A-C, drawing a standard curve by taking a light absorption value as a vertical coordinate and ammonia nitrogen concentration as a horizontal coordinate, fitting to obtain a standard curve equation, transferring the sample solution with the same volume to measure absorbance, and obtaining the ammonia nitrogen concentration of the mariculture pond according to the standard curve equation. According to the method, the pH of a reaction system is improved by adding a sodium hydroxide solution, the interference of calcium, magnesium, iron, manganese and other ions in a seawater sample is shielded, the ammonia color development in the seawater and brackish water with the salinity of below 30 is realized by complexing the potassium mercury iodide solution in the water, the ammonia nitrogen content is measured by colorimetry through a spectrophotometer, the required reagent dosage is small, the reaction stability time is long, the application range is wide, the precision and the repeatability are good, and the method is suitable for various mariculture water bodies.
Description
Technical Field
The invention relates to the field of environmental detection and analysis, in particular to a method for measuring the ammonia nitrogen content of a mariculture water body.
Background
Ammonia nitrogen is a common pollutant in the aquaculture water body, is a main product of protein catabolism, residual bait and excrement decomposition of a mariculture object, and can be accumulated in the water body in the aquaculture process. The excessive ammonia nitrogen in the water body can cause negative influence on the growth, survival and health of the cultured objects and economic loss, so that the method has important significance in conveniently, quickly and universally measuring the ammonia nitrogen content in the mariculture pond in the production of mariculture.
The method for measuring ammonia nitrogen in seawater is characterized by that under the condition of alkaline condition, sodium hypobromite can be used for oxidizing ammonia in seawater into nitrite, and the total quantity of nitrite nitrogen can be measured by using diazo-azo spectrophotometry, and the original nitrite content can be deducted so as to obtain the concentration of ammonia nitrogen. The method has high requirements on experimental reagents, wherein the sodium hypobromite solution is easy to decompose and difficult to store under natural conditions, and the method involves more reagents and has complex steps, so that the method is inconvenient to directly use in production. In a sample containing more pollutants, organic matters and nitrite, such as a water body of a marine aquaculture pond, the method often causes results with poor repeatability and accuracy due to interference of various pollutants. In addition, an indophenol blue spectrophotometry can be adopted for measuring ammonia nitrogen in seawater, the principle is that ammonia oxidation is carried out under the action of hypochlorous acid to generate chloramine, the chloramine reacts with phenol to generate an indophenol blue complex, and a spectrophotometer is used for detecting the absorbance of the complex at 640 nm.
The method for measuring ammonia nitrogen by using a nano reagent spectrophotometry is a good method for measuring ammonia nitrogen by fresh water, ammonia can react with a mercuric potassium iodide solution to generate a reddish brown colloidal compound in an alkaline environment, the color is strongly absorbed within a wider wavelength, the absorption luminosity of the complex is in direct proportion to the content of ammonia nitrogen, and the wavelength for measurement is generally 410-425nm. However, when the calcium and magnesium ions in the water sample are too high, the calcium and magnesium ions react with the reaction reagent to generate turbidity or precipitation to interfere with the measurement, and the measurement cannot be generally carried out on seawater or a water sample containing seawater and containing high calcium, magnesium, iron, manganese and the like. For example, chinese patent application (CN 202111190348) discloses a method for measuring the content of ammonia nitrogen in seawater by using a na's reagent spectrophotometry, but in the method, the amounts of a potassium sodium tartrate solution and a na's reagent are large, the total amount reaches 90% of a sample to be measured, and the concentration of the potassium sodium tartrate solution required by a reaction needs to be adjusted according to salinity, so that the method cannot be directly used in production, is troublesome in actual operation, and is not suitable for mariculture.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the method for measuring the ammonia nitrogen content of the mariculture water body, which is low in reagent consumption, suitable for the mariculture water bodies with various salinity, convenient and fast to operate and suitable for being directly used in mariculture.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention provides a method for measuring the ammonia nitrogen content of a mariculture water body, which comprises the following steps:
step 1: sample pretreatment;
taking a mariculture water body as a sample to be detected, filtering the sample by a 0.45 mu m needle filter, placing the sample in a conical flask, and determining the salinity of the sample to be detected;
step 2: reagent preparation, comprising:
1g/L ammonia nitrogen stock solution: putting ammonium chloride (AR) in a 105 ℃ oven for drying for more than 2h, weighing 3.819g, and dissolving in 1L of deionized water;
blank solution: ammonia-free seawater with the same salinity as the sample to be detected;
standard solution: diluting the ammonia nitrogen stock solution into ammonia nitrogen standard solutions with different concentrations by using the blank solution as a diluent;
sample solution: if the ammonia nitrogen concentration of the sample is too high, the pretreated sample solution can be diluted by a blank solution;
reagent A: a potassium sodium tartrate solution;
and (3) reagent B: a sodium hydroxide solution;
and (3) reagent C: mercury potassium iodide solution;
and 3, step 3: drawing a standard curve comprising
(3a) Respectively taking a certain volume of the standard solution, and placing the standard solution in different test tubes or colorimetric tubes;
(3b) Adding a reagent A in a volume ratio of 5.1-0.2 by taking the volume of the standard solution as a reference, immediately mixing, then immediately adding a reagent B in a volume ratio of 5;
(3c) Taking the volume of the standard solution as a reference, adding reagents C with the volume ratio of 5.1-0.2 respectively, uniformly mixing, standing for 10min, and waiting for the color to be stable;
(3d) Using a spectrophotometer to take a 1cm cuvette under the wavelength of 420nm, using deionized water for zero calibration, and measuring a light absorption value;
(3e) Drawing a standard curve by taking the light absorption value as a vertical coordinate and the ammonia nitrogen concentration (mg/L) as a horizontal coordinate, and fitting to obtain a standard curve equation;
and 4, step 4: sample assay comprising:
transferring a sample solution with the same volume according to the standard curve solution, and placing the sample solution in a test tube; measuring the absorbance of the sample solution according to (3 b) to (3 e) in step 3;
and 5: and comparing the sample tube with a standard curve equation to obtain the ammonia nitrogen concentration of the mariculture pond.
Preferably, the concentration of the reagent A is 0.25-0.5g/mL, and 25-50g of potassium sodium tartrate is dissolved in deionized water to be 100mL.
Preferably, the concentration of the reagent B is 0.4-0.5g/mL, and 40-50g of sodium hydroxide is dissolved in deionized water to be 100mL.
Preferably, the preparation method of the reagent C comprises the following steps: dissolving 7g of potassium iodide in deionized water, continuously weighing 10g of mercuric iodide to dissolve in the potassium iodide solution, and fixing the volume to 100mL.
Preferably, the ammonia nitrogen concentration of the standard solution is 0-2mg/L, and at least 5 standard solutions with different ammonia nitrogen concentrations are prepared by adopting the blank solution and the ammonia nitrogen stock solution.
Preferably, the minimum detection limit is 0.05mg/L.
Preferably, the sample to be tested is selected from seawater samples with salinity not more than 30 per thousand.
Compared with the prior art, the invention has the beneficial effects that:
(1) The method for measuring the ammonia nitrogen content of the mariculture water body improves the pH value of the reaction system and enhances the shielding capability of the potassium sodium tartrate by adding the sodium hydroxide solution into the reaction system, can shield the interference of calcium, magnesium, iron, manganese and other ions in a seawater sample, realizes the ammonia color development in the seawater complexing water body by the potassium mercuric iodide solution in 0-30 per mill, and measures the ammonia nitrogen content in the mariculture water body by colorimetry through a spectrophotometer.
(2) The reagent used in the invention has simple types, small reagent usage amount which is only 2-4% of the volume of the solution to be detected, pollution reduction, cost saving and simple operation, is universal for mariculture water bodies with different salinity, can be simplified into a rapid detection kit, and is suitable for rapid use in production practice through spectrophotometer colorimetry.
Drawings
FIG. 1 is a standard curve of ammonia nitrogen with salinity of 30 per mill in the example.
FIG. 2 is the standard curve of ammonia nitrogen with salinity of 20 per mill in the examples.
FIG. 3 is the standard curve of ammonia nitrogen with salinity of 10 per mill in the example.
FIG. 4 is the standard curve of ammonia nitrogen with salinity of 5% o in the examples.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It should be apparent that the described embodiments are only some of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
Example 1
The ammonia nitrogen concentration of the aquaculture water sample of the seawater aquaculture pond with the salinity of 30 per thousand is determined, and the following reagents or solutions are prepared:
ammonia-free seawater: diluting with ammonia-free brine (filtered by needle filter) with salinity of 90 ‰, and diluting with ammonia-free deionized water to salinity of 30 ‰.
1g/L ammonia nitrogen stock solution: the ammonium chloride is dried in an oven at 105 ℃ for more than 2h, and 3.819g of deionized water is weighed and dissolved in 1L.
A sample to be tested: the testing sample is prepared by ammonia-free seawater and 1g/L ammonia nitrogen stock solution, and the salinity of the testing sample is 30 per mill, and the ammonia nitrogen content is 0.3, 0.5 and 0.8 mg/L.
Standard solution: the ammonia-free seawater is prepared from ammonia-free seawater and 1g/L ammonia nitrogen stock solution, and the salinity of the standard solution is 30 per mill, and the ammonia nitrogen contents of the standard solution are respectively 0, 0.1, 0.2, 0.4, 0.6, 1.0, 1.5 and 2.0 mg/L.
Reagent A: weighing 25g of sodium potassium tartrate, heating and dissolving the sodium potassium tartrate by using deionized water, cooling, and fixing the volume to 100mL to prepare 0.25g/mL sodium potassium tartrate solution.
And (3) reagent B: 40g of sodium hydroxide is weighed and dissolved by deionized water, and the volume is determined to be 100mL after cooling, thus preparing 0.4g/mL of sodium hydroxide solution.
And (3) reagent C: weighing 7g of potassium iodide, dissolving the potassium iodide with deionized water, continuously weighing 10g of mercuric iodide, dissolving the mercuric iodide in the potassium iodide solution, and making the volume to be 100mL to prepare 0.17g/mL mercuric iodide solution.
The determination step comprises:
1) Drawing of standard curve
Respectively taking 5mL of standard solutions with different ammonia nitrogen concentrations in 15mL test tubes, sequentially adding 150 muL of reagent A into each test tube, immediately mixing, adding 150 muL of reagent B, immediately mixing, adding 150 muL of reagent C, mixing, waiting for 10 minutes, and measuring the absorbance value by using a spectrophotometer at a wavelength of 420nm and using deionized water as a reference. And drawing a standard curve (figure 1) by taking the absorbance value as a vertical coordinate and the ammonia nitrogen concentration as a horizontal coordinate.
2) Sample assay
Taking 5mL of a sample to be measured and 15mL of a test tube, sequentially adding 150 muL of the reagent A into the test tube, immediately mixing the reagent A and the reagent B, adding 150 muL of the reagent C, mixing the reagent A and the reagent C, waiting for 10 minutes, measuring the absorbance value by using a spectrophotometer under the wavelength of 420nm and taking deionized water as a reference, calculating the measured value according to a standard curve, and measuring each sample for 3 times.
As shown in FIG. 1, the standard curve is y =0.183x +0.0461 2 =0.9994, it can be seen that good linearity is exhibited in the range of 0-2 mg/L.
The measurement results are shown in table 1, the measurement results are basically consistent with actual values, the coefficient of variation is less than 5%, and the method has good accuracy and repeatability.
Table 1: determination of sample in seawater with salinity of 30 per mill
Example 2
And (3) measuring the ammonia nitrogen concentration of the sample with the salinity of 20 per mill, and preparing the following reagents or solutions:
ammonia-free seawater: diluting with ammonia-free brine (filtered by needle filter) with salinity of 90 ‰, and diluting with ammonia-free deionized water to salinity of 20 ‰.
1g/L ammonia nitrogen stock solution: the ammonium chloride is dried in an oven at 105 ℃ for more than 2h, and 3.819g of the ammonium chloride is weighed and dissolved in 1L of deionized water.
A sample to be tested: the sample to be detected is prepared by ammonia-free seawater and 1g/L ammonia nitrogen stock solution, and the salinity of the sample to be detected is 20 per mill, and the ammonia nitrogen content of the sample to be detected is 0.3, 0.5 and 0.8 mg/L.
Standard solution: the ammonia-free seawater and the ammonia nitrogen stock solution with the salinity of 20 per mill are respectively 0, 0.1, 0.2, 0.4, 0.6, 1.0, 1.5 and 2.0 mg/L.
Reagent A: weighing 25g of potassium sodium tartrate, heating and dissolving the potassium sodium tartrate by using deionized water, cooling, and fixing the volume to 100mL to prepare 0.25g/mL potassium sodium tartrate solution.
And (3) reagent B: weighing 40g of sodium hydroxide, dissolving with deionized water, cooling, and diluting to 100mL to obtain 0.4g/mL sodium hydroxide solution.
And (3) reagent C: weighing 7g of potassium iodide, dissolving the potassium iodide in deionized water, continuously weighing 10g of mercuric iodide, dissolving the mercuric iodide in a potassium iodide solution, and preparing a 0.17g/mL mercuric iodide solution after the volume is up to 100mL.
The determination step comprises:
1) Drawing of standard curve
Respectively taking 5mL of standard solutions with different ammonia nitrogen concentrations in 15mL test tubes, sequentially adding 150 muL of reagent A into each test tube, immediately mixing, adding 150 muL of reagent B, immediately mixing, adding 150 muL of reagent C, mixing, waiting for 10 minutes, and measuring the absorbance value by using a spectrophotometer at a wavelength of 420nm and using deionized water as a reference. And drawing a standard curve (figure 2) by taking the absorbance value as the ordinate and the ammonia nitrogen concentration as the abscissa.
2) Sample assay
Taking 5mL of a sample to be measured and 15mL of a test tube, sequentially adding 150 muL of the reagent A into the test tube, immediately mixing the reagent A and the reagent B, adding 150 muL of the reagent C, mixing the reagent A and the reagent C, waiting for 10 minutes, measuring the absorbance value by using a spectrophotometer under the wavelength of 420nm and taking deionized water as a reference, calculating the measured value according to a standard curve, and measuring each sample for 3 times.
As shown in FIG. 2, the standard curve is y =0.2082x +0.0592 2 =0.9991, it was found that good linearity was exhibited in the range of 0-2 mg/L.
The measurement results are shown in table 2, the measurement results are basically consistent with actual values, the coefficient of variation is less than 5%, and the method has good accuracy and repeatability.
Table 2: determination of sample in seawater with salinity of 20 per mill
| Sample (mg/mL) | Mean value (mg/mL) | Standard deviation (mg/mL) | Coefficient of variation (%) | Recovery (%) |
| 0.3 | 0.30 | 0.01 | 3.8 | 97-105 |
| 0.5 | 0.49 | 0.02 | 3.9 | 94-102 |
| 0.8 | 0.81 | 0.01 | 1.8 | 99-102 |
Example 3
And (3) measuring the ammonia nitrogen concentration of the sample with the salinity of 10 per mill, and preparing the following reagent or solution:
ammonia-free seawater: diluting with ammonia-free brine (filtered by needle filter) with salinity of 90 ‰, and diluting with ammonia-free deionized water to salinity of 10 ‰.
1g/L ammonia nitrogen stock solution: the ammonium chloride is dried in an oven at 105 ℃ for more than 2h, and 3.819g of deionized water is weighed and dissolved in 1L.
A sample to be tested: the sample to be detected is prepared by ammonia-free seawater and 1g/L ammonia nitrogen stock solution, and the salinity of the sample to be detected is 10 per mill, and the ammonia nitrogen content of the sample to be detected is 0.3, 0.5 and 0.8 mg/L.
Standard solution: the ammonia-free seawater and the 1g/L ammonia nitrogen stock solution are prepared into standard solutions with the salinity of 10 per mill and the ammonia nitrogen content of 0, 0.1, 0.2, 0.4, 0.6, 1.0, 1.5 and 2.0mg/L respectively.
Reagent A: weighing 25g of potassium sodium tartrate, heating and dissolving the potassium sodium tartrate by using deionized water, cooling, and fixing the volume to 100mL to prepare 0.25g/mL potassium sodium tartrate solution.
And a reagent B: 40g of sodium hydroxide is weighed and dissolved by deionized water, and the volume is determined to be 100mL after cooling, thus preparing 0.4g/mL of sodium hydroxide solution.
And (3) reagent C: weighing 7g of potassium iodide, dissolving the potassium iodide in deionized water, continuously weighing 10g of mercuric iodide, dissolving the mercuric iodide in a potassium iodide solution, and preparing a 0.17g/mL mercuric iodide solution after the volume is up to 100mL.
The determination step comprises:
1) Drawing of standard curve
Respectively taking 5mL of standard solutions with different ammonia nitrogen concentrations in 15mL test tubes, sequentially adding 150 muL of reagent A into each test tube, immediately mixing, adding 150 muL of reagent B, immediately mixing, adding 150 muL of reagent C, mixing, waiting for 10 minutes, and measuring the absorbance value by using a spectrophotometer at a wavelength of 420nm and using deionized water as a reference. And drawing a standard curve (figure 2) by taking the absorbance value as the ordinate and the ammonia nitrogen concentration as the abscissa.
2) Sample assay
Taking 5mL of a sample to be measured and 15mL of a test tube, sequentially adding 150 muL of the reagent A into the test tube, immediately mixing the reagent A and the reagent B, adding 150 muL of the reagent C, mixing the reagent A and the reagent C, waiting for 10 minutes, measuring the absorbance value by using a spectrophotometer under the wavelength of 420nm and taking deionized water as a reference, calculating the measured value according to a standard curve, and measuring each sample for 3 times.
As shown in FIG. 3, the standard curve is y =0.2201x +0.0253 2 =0.9988, it is seen that good linearity is exhibited in the range of 0-2 mg/L.
The measurement results are shown in table 3, the measurement results are basically consistent with the actual values, the coefficient of variation is less than 5%, and the method has good accuracy and repeatability.
Table 3: determination of sample in seawater with salinity of 10 per mill
| Sample (mg/mL) | Mean value (mg/mL) | Standard deviation (mg/mL) | Coefficient of variation (%) | Recovery (%) |
| 0.3 | 0.30 | 0.01 | 3.0 | 96-104 |
| 0.5 | 0.51 | 0.02 | 3.1 | 98-105 |
| 0.8 | 0.80 | 0.03 | 3.6 | 96-104 |
Example 4
And (3) measuring the ammonia nitrogen concentration of the sample with salinity of 5 per mill, and preparing the following reagents or solutions:
ammonia-free seawater: using ammonia-free brine with the salinity of 90 per mill (filtered by a needle type filter), and diluting the brine with ammonia-free deionized water until the salinity is 5 per mill.
1g/L ammonia nitrogen stock solution: the ammonium chloride is dried in an oven at 105 ℃ for more than 2h, and 3.819g of deionized water is weighed and dissolved in 1L.
A sample to be tested: the sample to be detected is prepared by ammonia-free seawater and 1g/L ammonia nitrogen stock solution, and the salinity of the sample to be detected is 5 per mill, and the ammonia nitrogen content of the sample to be detected is 0.3, 0.5 and 0.8 mg/L.
Standard solution: the ammonia-free seawater and the 1g/L ammonia nitrogen stock solution are prepared into standard solutions with the salinity of 5 per mill and the ammonia nitrogen content of 0, 0.1, 0.2, 0.4, 0.6, 1.0, 1.5 and 2.0mg/L respectively.
Reagent A: weighing 25g of potassium sodium tartrate, heating and dissolving the potassium sodium tartrate by using deionized water, cooling, and metering to 100mL to prepare 0.25g/mL potassium sodium tartrate solution.
And (3) reagent B: 40g of sodium hydroxide is weighed and dissolved by deionized water, and the volume is determined to be 100mL after cooling, thus preparing 0.4g/mL of sodium hydroxide solution.
And (3) reagent C: weighing 7g of potassium iodide, dissolving the potassium iodide in deionized water, continuously weighing 10g of mercuric iodide, dissolving the mercuric iodide in a potassium iodide solution, and preparing a 0.17g/mL mercuric iodide solution after the volume is up to 100mL.
The determination step comprises:
1) Drawing of standard curve
Respectively taking 5mL of standard solutions with different ammonia nitrogen concentrations in 15mL test tubes, sequentially adding 150 muL of reagent A into each test tube, immediately mixing, adding 150 muL of reagent B, immediately mixing, adding 150 muL of reagent C, mixing, waiting for 10 minutes, and measuring the absorbance value by using a spectrophotometer at a wavelength of 420nm and using deionized water as a reference. And drawing a standard curve (figure 4) by taking the absorbance value as the ordinate and the ammonia nitrogen concentration as the abscissa.
2) Sample assay
Taking 5mL of a sample to be measured and 15mL of a test tube, sequentially adding 150 muL of the reagent A into the test tube, immediately mixing the reagent A and the reagent B, adding 150 muL of the reagent C, mixing the reagent A and the reagent C, waiting for 10 minutes, measuring the absorbance value by using a spectrophotometer under the wavelength of 420nm and taking deionized water as a reference, calculating the measured value according to a standard curve, and measuring each sample for 3 times.
As shown in FIG. 4, the standard curve is y =0.189x +0.0311 2 =0.9995, it is seen that good linearity is exhibited in the range of 0-2 mg/L.
The measurement results are shown in table 4, the measurement results are basically consistent with the actual values, the coefficient of variation is less than 5%, and the method has good accuracy and repeatability.
Table 4: determination of sample in seawater with salinity of 5 per mill
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments. Those skilled in the art should appreciate that many modifications and variations are possible in light of the above teaching without departing from the scope of the invention.
Claims (7)
1. A method for measuring the ammonia nitrogen content of a mariculture water body is characterized by comprising the following steps:
step 1: sample pretreatment;
taking a mariculture water body as a sample to be detected, filtering the sample by a 0.45 mu m needle filter, placing the sample in a conical flask, and determining the salinity of the sample to be detected;
step 2: reagent preparation comprising:
1g/L ammonia nitrogen stock solution: putting ammonium chloride in a 105 ℃ oven for drying for more than 2h, weighing 3.819g, and dissolving in 1L of deionized water;
blank solution: ammonia-free seawater with the same salinity as the sample to be detected;
standard solution: diluting the ammonia nitrogen stock solution into ammonia nitrogen standard solutions with different concentrations by using the blank solution as a diluent;
sample solution: if the ammonia nitrogen concentration of the sample is too high, the pretreated sample solution can be diluted by a blank solution;
reagent A: a potassium sodium tartrate solution;
and (3) reagent B: a sodium hydroxide solution;
and (3) reagent C: mercury potassium iodide solution;
and 3, step 3: and (3) drawing a standard curve, including:
(3a) Respectively taking a certain volume of the standard solution, and placing the standard solution in different test tubes or colorimetric tubes;
(3b) Taking the volume of the standard solution as a reference, adding the reagent A with the volume ratio of 5.1-0.2, immediately mixing, then immediately adding the reagent B with the volume ratio of 5;
(3c) Taking the volume of the standard solution as a reference, adding reagents C with the volume ratio of 5.1-0.2 respectively, uniformly mixing, standing for 10min, and waiting for the color to be stable;
(3d) Using a spectrophotometer at the wavelength of 420nm, taking a 1cm cuvette, calibrating zero with deionized water, and measuring a light absorption value;
(3e) Drawing a standard curve by taking the light absorption value as a vertical coordinate and the ammonia nitrogen concentration (mg/L) as a horizontal coordinate, and fitting to obtain a standard curve equation;
and 4, step 4: a sample assay comprising:
transferring sample solution with the same volume according to the standard curve solution, and placing the sample solution in a test tube; measuring the absorbance of the sample solution according to (3 b) to (3 e) in step 3;
and 5: and comparing the sample tube with a standard curve equation to obtain the ammonia nitrogen concentration of the mariculture pond.
2. The method for determining the ammonia nitrogen content in the mariculture water body according to claim 1, wherein the concentration of the reagent A is 0.25-0.5g/mL, and 25-50g of potassium sodium tartrate is dissolved in deionized water to a constant volume of 100mL.
3. The method for determining the ammonia nitrogen content in the mariculture water body according to claim 1, wherein the concentration of the reagent B is 0.4-0.5g/mL, and 40-50g of sodium hydroxide is dissolved in deionized water to a constant volume of 100mL.
4. The method for determining the ammonia nitrogen content in the mariculture water body according to claim 1, wherein the preparation method of the reagent C comprises the following steps: dissolving 7g of potassium iodide in deionized water, continuously weighing 10g of mercuric iodide to dissolve in the potassium iodide solution, and keeping the volume constant at 100mL.
5. The method for determining the ammonia nitrogen content in the mariculture water body according to claim 1, wherein the ammonia nitrogen concentration of the standard solution is 0-2mg/L, and at least 5 standard solutions with different ammonia nitrogen concentrations are prepared by adopting the blank solution and the ammonia nitrogen stock solution.
6. The method for determining the ammonia nitrogen content in the mariculture water body according to claim 1, wherein the lowest detection limit is 0.05mg/L.
7. The method for determining the ammonia nitrogen content in the seawater culture water body according to claim 1, wherein the sample to be tested is selected from a seawater sample with salinity not more than 30 per thousand.
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