CN114965453A - Nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride, using method and vegetable nitrate nitrogen detection kit - Google Patents
Nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride, using method and vegetable nitrate nitrogen detection kit Download PDFInfo
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Abstract
The application relates to the field of detection reagents, and particularly discloses a nitrate detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride, a using method and a vegetable nitrate nitrogen detection box. The nitrate detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride comprises 0.5-1.5 parts by mass of dopamine hydrochloride, 0.5-1.5 parts by mass of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, 2-6 parts by mass of ammonium acetate and 87.5-96 parts by mass of water. The use method of the nitrate radical detection reagent containing the 3-methyl-2-benzothiazolinone hydrazone hydrochloride comprises the following steps: and making a standard curve, mixing and developing, measuring absorbance, comparing with the standard curve and the like. The vegetable nitrate nitrogen detection kit contains the nitrate nitrogen detection reagent containing the 3-methyl-2-benzothiazolinone hydrazone hydrochloride. This application has improved the stability and the precision of reagent through the addition of ammonium acetate, has reduced the quantity of plus acidizing fluid.
Description
Technical Field
The application relates to the field of detection reagents, in particular to a nitrate detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride, a using method and a vegetable nitrate nitrogen detection box.
Background
The determination of the nitrate content in the liquid is an important means for researching the nitrogen content in water bodies such as lakes and the like and the nitrate nitrogen content in vegetables, and has important significance for environmental protection, food safety and the like.
In the related technology, nitrate radicals are measured by adopting 3-methyl-2-benzothiazolinone hydrazone hydrochloride and dopamine hydrochloride; the mechanism of the method is as follows: under the acidic condition, nitrate radical can firstly react with dopamine hydrochloride, and the obtained reaction product then reacts with 3-methyl-2-benzothiazolinone hydrazone hydrochloride to generate a red azo product; and (4) detecting the absorbance of the red-colored product by a spectrophotometer, and obtaining the nitrate content in the liquid by means of a pre-drawn standard curve. The method has the advantages of rapid detection and accurate result.
However, since reagents prepared from 3-methyl-2-benzothiazolinone hydrazone hydrochloride and dopamine hydrochloride are often in contact with air during detection, carbon dioxide in the air enters the reagents at the time and carbonate which can reduce the pH value of the reagents is generated, and the reagents are acidic after being in contact with the air for a long time; the 3-methyl-2-benzothiazolinone hydrazone hydrochloride and the dopamine hydrochloride can slowly react with each other or with each other under a slightly acidic condition, so that the 3-methyl-2-benzothiazolinone hydrazone hydrochloride and the dopamine hydrochloride are consumed, the whole reagent is discolored, the accuracy of a final absorbance detection result is influenced, and the precision of nitrate detection is further influenced. Therefore, the stability of the agent formulated from 3-methyl-2-benzothiazolinone hydrazone hydrochloride and dopamine hydrochloride is in need of improvement.
In the related art, a phosphate buffer solution is added to the reagent to buffer acidity caused by carbon dioxide entering the reagent, and a preferable effect is obtained. However, the inventor finds that the increase of the system acidity during detection is beneficial to the quicker and sufficient reaction between the reagent and nitrate radical, and further beneficial to the more accurate and quicker detection; the use of the buffer solution buffers the acidity of the system during detection, so that more acid liquor (usually strong acid) needs to be used to enable the system to reach the strong acidity, the demand of the acid liquor is increased, and certain adverse effect is brought to the safety during detection.
Disclosure of Invention
In order to reduce the use of acid liquor on the premise of ensuring the stability and accuracy of the reagent, the application provides a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride, a use method and a vegetable nitrate nitrogen detection kit.
In a first aspect, a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride is provided, and the following technical scheme is adopted:
the nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride is prepared from the following raw materials in parts by mass: 0.5-1.5 parts of dopamine hydrochloride, 0.5-1.5 parts of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, 2-6 parts of ammonium acetate and 87.5-96 parts of water.
By adopting the technical scheme, the ammonium acetate is alkaline in water and has the buffering effect; therefore, the addition of ammonium acetate can effectively reduce the reduction effect of carbon dioxide entering the reagent on the pH value of the reagent, thereby effectively reducing the problem of reaction discoloration of the reagent before the detection, and improving the stability of the reagent. Meanwhile, ammonium acetate can be decomposed under the heating condition; while ammonia is released, part of acetic acid is left in the reagent and becomes acid liquor for providing acidity for the reagent, so that the reaction of dopamine hydrochloride, 3-methyl-2-benzothiazolinone hydrazone hydrochloride and nitrate is promoted, the detection precision of the reagent is improved, and the dosage of the external acid liquor can be reduced.
In a specific possible embodiment, the raw material further comprises 0.3 to 0.7 parts by mass of a vegetable gum powder.
By adopting the technical scheme, the plant rubber powder can form a three-dimensional network structure in water, so that the stability of detection substrates such as dopamine hydrochloride and 3-methyl-2-benzothiazolinone hydrazone hydrochloride in the reagent is improved, the problem of advanced reaction of part of detection substrates is reduced, and the overall stability of the detection reagent is improved.
In a particular possible embodiment, the vegetable gum powder is guar gum powder or tonka-bean gum powder.
By adopting the technical scheme, the use of the guar gum powder and the tonka-bean gum powder is beneficial to improving the stability of the reagent.
In a specific possible embodiment, the raw material further includes 0.5 to 5 parts by mass of a surfactant.
By adopting the technical scheme, the surfactant can improve the stability of detection substrates such as dopamine hydrochloride, 3-methyl-2-benzothiazolinone hydrazone hydrochloride and the like in a reagent; the surfactant is matched with the plant rubber powder, so that the stability of the reagent is further improved, and the storage time of the reagent is prolonged.
In a specific embodiment, the surfactant is one of polyoxyethylene sorbitan fatty acid ester surfactant, polyethylene glycol octyl phenyl ether surfactant, and alkylphenol polyoxyethylene ether surfactant.
By adopting the technical scheme, the polyoxyethylene sorbitan fatty acid ester surfactant, the polyethylene glycol octyl phenyl ether surfactant and the alkylphenol polyoxyethylene ether surfactant are beneficial to improving the stability of the detection substrate in the reagent.
In a second aspect, a method for using the nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride is provided, and the following technical scheme is adopted:
the use method of the nitrate radical detection reagent containing the 3-methyl-2-benzothiazolinone hydrazone hydrochloride comprises the following steps:
configuration of NO 3 - -N standard solutions; mixing the standard solution with acid liquor and a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride to obtain standard mixed liquor, controlling the temperature of the standard mixed liquor to be higher than 60 ℃, and enabling the standard mixed liquor to turn red; then measuring the absorbance of the standard mixed solution at the wavelength of 530 nm;
making a standard curve by measuring the absorbance of the standard mixed solution with different nitrate concentration at the wavelength of 530nm after the standard mixed solution turns red;
mixing a liquid to be detected with an acid solution and a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride to obtain a mixed liquid to be detected, controlling the temperature of the mixed liquid to be detected to be more than 60 ℃, and enabling the mixed liquid to be detected to turn red; and then measuring the absorbance of the mixed solution to be detected at the wavelength of 530nm and comparing the absorbance with a standard curve to obtain the concentration of nitrate in the solution to be detected.
By adopting the technical scheme, the nitrate radical detection reagent containing the 3-methyl-2-benzothiazolinone hydrazone hydrochloride can quickly and accurately detect the content of nitrate radicals in the liquid to be detected.
In a particular embodiment, the acid solution is sulfuric acid.
By adopting the technical scheme, the sulfuric acid has stronger acidity, and the acidity of the reagent can be effectively improved in detection, so that conditions are provided for the smooth reaction of the dopamine hydrochloride, the 3-methyl-2-benzothiazolinone hydrazone hydrochloride and the nitrate radical.
The third aspect provides a vegetable nitrate nitrogen detection box, which adopts the following technical scheme:
the vegetable nitrate nitrogen detection kit contains the nitrate nitrogen detection reagent containing the 3-methyl-2-benzothiazolinone hydrazone hydrochloride.
By adopting the technical scheme, the kit can effectively determine the content of nitrate nitrogen in vegetables, and has the advantages of rapidness, accuracy and stable preservation.
In summary, the present application has at least one of the following beneficial technical effects:
1. the application utilizes the alkaline characteristics and the buffering effect of ammonium acetate, and can effectively reduce the reduction effect of carbon dioxide on the pH value of the reagent, thereby reducing the problem of color change of the reagent before the detection of the reagent and improving the stability of the reagent. Meanwhile, the ammonium acetate can release acid liquor during heating, so that the detection precision of the reagent can be improved, and the dosage of the external acid liquor can be reduced.
2. According to the application, the plant rubber powder is added, the three-dimensional network structure formed by the plant rubber powder in water is utilized, the stability of a detection substrate in a reagent is improved, the problem that part of the detection substrate reacts in advance is reduced, and the stability of the detection reagent is improved.
3. The surfactant is added, and the stability of the reagent can be further improved and the storage time of the reagent can be prolonged by matching the surfactant with the plant gum powder.
Detailed Description
The present application will be described in further detail with reference to examples.
Example 1
The embodiment discloses a nitrate radical detection reagent (hereinafter referred to as detection reagent) containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride, which is prepared by uniformly mixing the following raw materials: 0.5g of dopamine hydrochloride, 1.5g of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, 2g of ammonium acetate and 96g of water.
Wherein dopamine hydrochloride and 3-methyl-2-benzothiazolinone hydrazone hydrochloride generate red azo compounds through the reaction with nitrate radicals to generate color marks. Ammonium acetate is alkalescent in water, has a buffering effect, and can effectively reduce the reduction effect of carbon dioxide in the air on the pH value of the detection reagent, thereby effectively reducing the problem of reaction discoloration of the detection reagent before the detection. Meanwhile, after being heated, the ammonium acetate can release ammonia and shows acidity in water, so that the reaction of dopamine hydrochloride, 3-methyl-2-benzothiazolinone hydrazone hydrochloride and nitrate is promoted, the detection precision of a detection reagent is improved, and the dosage of an external acid can be reduced.
In addition, in the present embodiment, the method of uniformly mixing the raw materials is a conventional method such as stirring mixing, ultrasonic mixing, and the like, and is not developed here.
The embodiment also discloses a using method of the detection reagent, which comprises the following steps:
s1, dissolving 0.361g potassium nitrate in 1L pure water to prepare NO with 50 mug/mL 3 - -N standard solutions; then taking different volumes of NO 3 - The N standard solutions were mixed with 3mL of 80 wt% sulfuric acid, 2mL of a detection reagent, and pure water to prepare 10mL of standard mixed solutions each having a nitrate concentration of 0.05. mu.g/mL, 0.1. mu.g/mL, 0.2. mu.g/mL, 0.4. mu.g/mL, and 0.6. mu.g/mL.
S2, taking standard mixed solutions with different nitrate radical concentrations, respectively controlling the temperature at 75 ℃, standing for 20min, and respectively enabling the standard mixed solutions to turn red; standing for 20min, and respectively placing standard mixed solutions with different nitrate concentration into a type 722 spectrophotometer; detecting the standard mixed solution at the wavelength of 530nm by contrast of a blank sample to obtain an absorbance value of the standard mixed solution; a standard curve is made by nitrate concentration and corresponding absorbance value.
It should be noted that the measurement of the absorbance of the liquid by the type 722 spectrophotometer and the calibration thereof are all performed conventionally, and therefore, no progress is made herein.
S3, uniformly mixing 1mL of to-be-detected liquid, 3mL of 80 wt% sulfuric acid, 2mL of detection reagent and 4mL of pure water to obtain a to-be-detected mixed liquid; then controlling the temperature of the mixed liquid to be detected at 75 ℃, standing for 20min, and then enabling the mixed liquid to be detected to turn red; standing for 20min, placing the mixed solution to be detected in a 722-type spectrophotometer, and detecting the mixed solution to be detected at 530nm wavelength by contrast of a blank sample to obtain the absorbance value of the mixed solution; and comparing the absorbance value with a standard curve to obtain the nitrate content in the liquid to be detected.
The embodiment of the application also discloses a kit for detecting nitrate nitrogen in vegetables, which contains the detection reagent.
When the vegetables need to be detected:
firstly, cleaning vegetables (such as fresh green vegetable leaves, celery leaves and the like), airing, and then cutting into small sections of 2 cm; placing the vegetable segments in a tissue triturator, and mashing the vegetable segments into vegetable pulp at the rotating speed of 12000 rpm; filtering the vegetable pulp with a 1000-mesh screen, centrifuging at 8000rpm for 5min, and collecting supernatant to obtain the liquid to be detected.
Then detecting the liquid to be detected according to the using method of the detection reagent to obtain the content of nitrate radical in the liquid to be detected; the nitrate nitrogen content in the vegetables can be obtained by conversion, namely the nitrate nitrogen content in the vegetables can be obtained.
The kit can effectively determine the content of nitrate nitrogen in vegetables, and has the advantages of rapidness, accuracy and stable preservation.
Examples 2 to 7
Examples 2-7 are essentially the same as example 1, except that: the ratio of the raw materials of the detection reagent is different, see table 1.
TABLE 1 raw material ratios of the detection reagents of examples 1 to 14
Note: the addition amount of each component is g.
Examples 8 to 10
Examples 8-10 are essentially the same as example 6, except that: the raw materials of the detection reagent also comprise plant gum powder, which is shown in table 1.
Specifically, in examples 8-10, the gum vegetable powder was guar gum powder having a particle size of 200 mesh and a 1 wt% concentration of 1000cps (25 ℃, NDJ-1, 30rpm, 4# rotor).
The plant rubber powder can form a three-dimensional network structure in water, and is favorable for improving the stability of dopamine hydrochloride and 3-methyl-2-benzothiazolinone hydrazone hydrochloride in the detection reagent, so that the overall stability of the detection reagent is improved. When the temperature is increased, the three-dimensional network structure becomes loose, so that the reaction of dopamine hydrochloride, 3-methyl-2-benzothiazolinone hydrazone hydrochloride and nitrate is not influenced.
Examples 11 to 14
Examples 11-14 are essentially the same as example 9, except that: the raw materials for the detection reagent also included surfactants, see table 1.
Specifically, in examples 11 to 14, the surfactant was Tween-80 of polyoxyethylene sorbitan fatty acid ester type. The surfactant has the function of stabilizing a system of the detection reagent, so that the storage time of the detection reagent is prolonged; and the addition of the surfactant can also promote the dopamine hydrochloride to be better dissolved in the detection reagent.
Example 15
This example is substantially the same as example 13 except that: in the raw materials of the detection reagent, the plant rubber powder is particularly coumaric rubber powder, the particle size of which is 120 meshes, and the 1 wt% concentration of which is 600cps (25 ℃, NDJ-1, 30rpm, 4# rotor).
Example 16
This example is substantially the same as example 13 except that: in the raw materials of the detection reagent, the surfactant is specifically Tritox-100 of polyethylene glycol octyl phenyl ether.
Example 17
This example is substantially the same as example 13 except that: in the raw materials of the detection reagent, the surfactant is OP-10 of alkylphenol polyoxyethylene.
Example 18
This example is substantially the same as example 13 except that: in the using method of the detection reagent, the adopted acid solution is hydrochloric acid with the concentration of 37 wt%, and the using amount is adjusted.
The steps related to the method are as follows:
s1, dissolving 0.361g potassium nitrate in 1L pure water to prepare NO with 50 mug/mL 3 - -N standard solutions; then taking different volumes of NO 3 - the-N standard solution was mixed with 6.5mL of 37 wt% hydrochloric acid, 2mL of a detection reagent, and pure water to prepare NO 3 - Each 10mL of standard mixture solutions having concentrations of 0.05. mu.g/mL, 0.1. mu.g/mL, 0.2. mu.g/mL, 0.4. mu.g/mL, and 0.6. mu.g/mL.
S3, uniformly mixing 1mL of to-be-detected liquid, 6.5mL of 37 wt% hydrochloric acid, 2mL of detection reagent and 0.5mL of pure water to obtain to-be-detected mixed liquid; then controlling the temperature of the mixed liquid to be detected at 75 ℃, standing for 20min, and then enabling the mixed liquid to be detected to turn red; standing for 20min, placing the mixed solution to be detected in a 722-type spectrophotometer, and detecting the mixed solution to be detected at 530nm wavelength by contrast of a blank sample to obtain the absorbance value of the mixed solution; and comparing the absorbance value with a standard curve to obtain the nitrate content in the liquid to be detected.
Example 19
This example is substantially the same as example 13 except that: in the using method S2 of the detection reagent, the temperature of the standard mixed solution is controlled at 60 ℃; meanwhile, in S3, the temperature of the mixture to be tested is controlled at 60 ℃.
Example 20
This example is substantially the same as example 13 except that: in the using method S2 of the detection reagent, the temperature of standard mixed liquid is controlled at 90 ℃; meanwhile, in S3, the temperature of the mixture to be tested is controlled at 90 ℃.
Example 21
This example is substantially the same as example 13 except that: in the method of using the detection reagent, the process parameters of each step are different.
The method specifically comprises the following steps:
s1, 0.722g potassium nitrate was dissolved in 1L pure water to prepare 100. mu.g/mL NO 3 - -N standard solutions; then taking different volumes of NO 3 - The N standard solutions were mixed with 2mL of 98 wt% sulfuric acid, 2mL of a detection reagent, and pure water to prepare 10mL of standard mixed solutions each having a nitrate concentration of 0.1. mu.g/mL, 0.3. mu.g/mL, 0.5. mu.g/mL, 0.7. mu.g/mL, and 0.9. mu.g/mL.
S2, taking standard mixed solutions with different nitrate radical concentrations, respectively controlling the temperature at 75 ℃, standing for 15min, and respectively enabling the standard mixed solutions to turn red; standing for 15min, and respectively placing standard mixed solutions with different nitrate concentration into a type 722 spectrophotometer; detecting the standard mixed solution at the wavelength of 530nm by contrast of a blank sample to obtain an absorbance value of the standard mixed solution; a standard curve is made by nitrate concentration and corresponding absorbance value.
S3, uniformly mixing 1mL of to-be-detected liquid, 2mL of 98 wt% sulfuric acid, 2mL of detection reagent and 5mL of pure water to form to-be-detected mixed liquid; then controlling the temperature of the mixed liquid to be detected at 75 ℃, standing for 15min, and then enabling the mixed liquid to be detected to turn red; standing for 15min, placing the mixed solution to be detected in a 722-type spectrophotometer, and detecting the mixed solution to be detected at 530nm wavelength by contrast of a blank sample to obtain the absorbance value of the mixed solution; and comparing the absorbance value with a standard curve to obtain the nitrate content in the liquid to be detected.
Example 22
This example is substantially the same as example 13 except that: in the method of using the detection reagent, the process parameters of each step are different.
The method specifically comprises the following steps:
s1, dissolving 0.722g potassium nitrate in 10L pure water to prepare 10 mu g/mL NO 3 - -N standard solutions; then taking different volumes of NO 3 - -N Standard solutionEach of the samples was mixed with 2.5mL of 90 wt% sulfuric acid, 2mL of a detection reagent, and pure water to prepare 10mL each of standard mixed solutions having nitrate concentrations of 0.05. mu.g/mL, 0.2. mu.g/mL, 0.4. mu.g/mL, 0.6. mu.g/mL, 0.8. mu.g/mL, and 1. mu.g/mL.
S2, taking standard mixed solutions with different nitrate concentration, respectively controlling the temperature at 75 ℃, standing for 23min, and respectively changing the standard mixed solutions into red; standing for 23min, and respectively placing standard mixed solutions with different nitrate concentration into a type 722 spectrophotometer; detecting the standard mixed solution at the wavelength of 530nm by contrast of a blank sample to obtain an absorbance value of the standard mixed solution; a standard curve is made by nitrate concentration and corresponding absorbance value.
S3, uniformly mixing 1mL of to-be-detected liquid, 2.5mL of 90 wt% sulfuric acid, 2mL of detection reagent and 4.5mL of pure water to obtain a to-be-detected mixed liquid; then controlling the temperature of the mixed liquid to be detected at 75 ℃, standing for 23min, and then enabling the mixed liquid to be detected to turn red; standing for 23min, placing the mixed solution to be detected in a type 722 spectrophotometer, and detecting the mixed solution to be detected at the wavelength of 530nm by contrast of a blank sample to obtain the absorbance value of the mixed solution; and comparing the absorbance value with a standard curve to obtain the nitrate content in the liquid to be detected.
Comparative example 1
The main difference between this comparative example and example 2 is that: in the raw materials of the detection reagent, no ammonium nitrate is added.
The method specifically comprises the following steps:
a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride is prepared by uniformly mixing the following raw materials: 1g of dopamine hydrochloride, 1g of 3-methyl-2-benzothiazolinone hydrazone hydrochloride and 98g of water.
Comparative example 2
The main difference between this comparative example and example 2 is that: in the raw material of the detection reagent, the amount of ammonium nitrate added was 1 g.
The method comprises the following specific steps:
a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride is prepared by uniformly mixing the following raw materials: 1g of dopamine hydrochloride, 1g of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, 1g of ammonium acetate and 97g of water.
Comparative example 3
The main difference between this comparative example and example 2 is that: in the raw materials of the detection reagent, sodium dihydrogen phosphate and disodium hydrogen phosphate are added instead of ammonium nitrate.
The method specifically comprises the following steps: a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride is prepared by uniformly mixing the following raw materials: 1g of dopamine hydrochloride, 1g of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, 1.2g of sodium dihydrogen phosphate, 1.2g of disodium hydrogen phosphate and 95.6g of water.
Comparative example 4
This comparative example is substantially the same as comparative example 3 except that: in the method of using the detection reagent, the amount of sulfuric acid added is increased.
The using method of the detection reagent comprises the following specific steps:
s1, dissolving 0.361g potassium nitrate in 1L pure water to prepare NO with 50 mug/mL 3 - -N standard solutions; then taking different volumes of NO 3 - The N standard solutions were mixed with 4.5mL of 80 wt% sulfuric acid, 2mL of a detection reagent, and pure water to prepare 10mL of each of standard mixed solutions having nitrate concentrations of 0.05. mu.g/mL, 0.1. mu.g/mL, 0.2. mu.g/mL, 0.4. mu.g/mL, and 0.6. mu.g/mL.
S2, taking standard mixed solutions with different nitrate radical concentrations, respectively controlling the temperature at 75 ℃, standing for 20min, and respectively turning the standard mixed solutions into red; standing for 20min, and respectively placing standard mixed solutions with different nitrate concentration into a type 722 spectrophotometer; detecting the standard mixed solution at the wavelength of 530nm by contrast of a blank sample to obtain an absorbance value of the standard mixed solution; a standard curve is made by nitrate concentration and corresponding absorbance value.
S3, uniformly mixing 1mL of to-be-detected liquid, 4.5mL of 80 wt% sulfuric acid, 2mL of detection reagent and 2.5mL of pure water to obtain a to-be-detected mixed liquid; then controlling the temperature of the mixed liquid to be detected at 75 ℃, standing for 20min, and then enabling the mixed liquid to be detected to turn red; standing for 20min, placing the mixed solution to be detected in a 722-type spectrophotometer, and detecting the mixed solution to be detected at 530nm wavelength by contrast of a blank sample to obtain the absorbance value of the mixed solution; and comparing the absorbance value with a standard curve to obtain the nitrate content in the liquid to be detected.
Performance detection
1. Detection deviation value A of detection reagent 0 : taking the detection reagents (both newly prepared) obtained in the examples 1-22 and the comparative examples 1-4, detecting the nitrate content of the detection liquid (specifically, the extract of the green vegetable leaves, the nitrate content is 50.12 mu g/mL) according to the respective corresponding using methods, and comparing the detection liquid with a standard value of 50.12 mu g/mL; taking the absolute value of the difference between the measured value and 50.12, and recording the absolute value as a detection deviation value A 0 (ii) a Five detections are carried out in parallel, and the deviation value A of the five detections is 0 The averages were taken and recorded in table 2. Detecting the deviation value A 0 The smaller the size, the higher the detection accuracy of the detection reagent.
2. Detection deviation value A of detection reagent placed for 90 hours 90 : taking the detection reagents obtained in the examples 1-22 and the comparative examples 1-4, and placing the detection reagents for 90 hours in an open environment at the temperature of 20 ℃; then, the nitrate content of the detection liquid (specifically the extracting liquid of the green vegetable leaves, the nitrate content is 50.12 mu g/mL) is detected according to the using method corresponding to each example and each comparative example, and is compared with the standard value of 50.12 mu g/mL; taking the absolute value of the difference between the measured value and 50.12, and recording the absolute value as a detection deviation value A 90 (ii) a Performing five parallel detections, and detecting deviation value A for five detections 90 The averages were taken and recorded in table 2.
3. The rising rate gamma of the detection deviation value of the detection reagent is measured before and after the reagent is placed for 90 hours: γ ═ a 90 -A 0 )/A 0 . The smaller the rising rate gamma of the detection deviation value of the detection reagent before and after being placed for 90 hours shows that the precision of the detection reagent is reduced the smaller, namely the deterioration condition of the detection reagent is lighter, and the stability of the detection reagent is better.
TABLE 2 results of measuring the Properties of the measuring reagents obtained in examples 1 to 22 and comparative examples 1 to 4
Referring to Table 2, it can be found from the test results of examples 1 to 22 that: the detection reagent obtained in each example of the application has a nitrate content detection deviation value of less than 0.18, and has a deviation ratio (detection deviation value/actual concentration of nitrate) of less than 3.6%, and shows good detection accuracy.
From the results of the tests of examples 2, 4 to 7 and comparative examples 1 to 2, it was found that: with the addition of ammonium acetate, the rising rate gamma of the detection deviation value of the obtained detection reagent is gradually reduced before and after the detection reagent is placed for 90 hours, namely the stability of the obtained detection reagent is gradually improved. This is due to: ammonium acetate is alkalescent to a certain extent and has the buffering effect, so that the problem that the pH value of carbon dioxide in the air is reduced when the carbon dioxide enters the detection reagent after being placed for a long time can be reduced, the problem that the detection reagent reacts and discolors in advance is effectively reduced, and the stability of the detection reagent is improved. Meanwhile, as the ammonium acetate can release acid after being heated, the acidity of the mixed solution to be tested can be improved, so that the reaction of the dopamine hydrochloride, the 3-methyl-2-benzothiazolinone hydrazone hydrochloride and nitrate radicals is more sufficient; therefore, under the condition that the adding amount of the sulfuric acid is the same during detection, the detection deviation value A of the obtained detection reagent is obtained along with the addition of the ammonium acetate 0 The detection accuracy is decreased, i.e., increased.
From the test results of example 2 and comparative examples 3 to 4, it can be found that: the phosphate buffer solution added in the detection reagent is similar to the ammonium acetate added in the detection reagent, and both can buffer acidity brought by carbon dioxide entering the detection reagent. However, ammonium acetate releases acid at elevated temperatures compared to phosphate buffered solutions and thus can work in conjunction with sulfuric acid to promote the reaction of dopamine hydrochloride, 3-methyl-2-benzothiazolinone hydrazone hydrochloride, with nitrate. Therefore, under the condition that the adding amount of the sulfuric acid is the same, the detection precision of the detection reagent obtained in the example 2 adopting the ammonium acetate is higher than that of the detection reagent obtained in the comparative example 3 adopting the phosphoric acid buffer solution; similarly, comparative example 4, which employs a phosphoric acid buffer solution, adds more sulfuric acid in order to achieve similar detection accuracy, thereby increasing the risk of operation; namely, description: the detection reagent obtained by the application reduces the use of acid liquor on the premise of ensuring stability and accuracy.
The results of the tests of example 6 and examples 8 to 10 were analyzed to find that: with the addition of the plant gum powder (guar gum powder), the rising rate gamma of the detection deviation value of the obtained detection reagent is reduced before and after the detection reagent is placed for 90 hours, namely the overall stability of the detection reagent is improved; the possible reasons are: guar gum powder can form a three-dimensional network structure in water, so that the stability of dopamine hydrochloride and 3-methyl-2-benzothiazolinone hydrazone hydrochloride in the detection reagent is improved, the problem that part of dopamine hydrochloride and/or 3-methyl-2-benzothiazolinone hydrazone hydrochloride reacts in advance is further solved, and the overall stability of the detection reagent is improved.
The results of the tests of example 9 and examples 11 to 14 were analyzed to show that: the surfactant (Tween-80) is added into the raw materials of the detection reagent, so that the stability of the dopamine hydrochloride and the 3-methyl-2-benzothiazolinone hydrazone hydrochloride in the detection reagent can be improved, and the stability of the detection reagent is further improved.
The results of the tests of comparative example 13 and example 15 can be obtained: the guar gum powder and the tonka-bean gum powder both play a positive role in improving the stability of the obtained detection reagent.
The results of the tests of comparative example 13 and examples 16 to 17 were as follows: the polyethylene glycol octyl phenyl ether surfactant, the alkylphenol polyoxyethylene ether surfactant and the polyoxyethylene sorbitan fatty acid ester surfactant are similar, and the stability of the obtained detection reagent is favorably improved.
The results of the tests of comparative example 13 and example 18 were obtained: hydrochloric acid is slightly less acidic than sulfuric acid, so dopamine hydrochloride, 3-methyl-2-benzothiazolinone hydrazone hydrochloride are slightly less reactive with nitrate, resulting in a slightly worse detection accuracy in example 18 than in example 13.
The results of the tests of comparative example 13 and examples 19 to 20 were obtained: the temperature of the standard mixed liquid and the mixed liquid to be detected is increased, namely the reaction temperature of the dopamine hydrochloride, the 3-methyl-2-benzothiazolinone hydrazone hydrochloride and the nitrate is increased, and the ammonium acetate can be decomposed to obtain more acid, so that the detection precision is improved.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (8)
1. The nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride is characterized in that: the feed is prepared from the following raw materials in parts by mass: 0.5-1.5 parts of dopamine hydrochloride, 0.5-1.5 parts of 3-methyl-2-benzothiazolinone hydrazone hydrochloride, 2-6 parts of ammonium acetate and 87.5-96 parts of water.
2. The nitrate detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride according to claim 1, characterized in that: the raw materials also comprise 0.3-0.7 parts by mass of plant rubber powder.
3. The nitrate detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride according to claim 2, characterized in that: the plant gum powder is guar gum powder or tonka bean gum powder.
4. The nitrate detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride according to claim 2, characterized in that: the raw material also comprises 0.5-5 parts by mass of a surfactant.
5. The nitrate detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride according to claim 4, wherein: the surfactant is one of polyoxyethylene sorbitan fatty acid ester surfactant, polyethylene glycol octyl phenyl ether surfactant and alkylphenol polyoxyethylene ether surfactant.
6. The use of the reagent for nitrate detection containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride according to any one of claims 1 to 5, characterized in that: the method comprises the following steps:
preparing NO 3-N standard solution; mixing the standard solution with acid liquor and a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride to obtain standard mixed liquor, controlling the temperature of the standard mixed liquor to be more than 60 ℃, and enabling the standard mixed liquor to turn red; then measuring the absorbance of the standard mixed solution at the wavelength of 530 nm;
making a standard curve by measuring the absorbance of the standard mixed solution with different nitrate concentration at the wavelength of 530nm after the standard mixed solution turns red;
mixing the liquid to be detected with acid liquor and a nitrate radical detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride to obtain a mixed liquid to be detected, controlling the temperature of the mixed liquid to be detected to be higher than 60 ℃, and enabling the mixed liquid to be detected to turn red; and then measuring the absorbance of the mixed solution to be detected at the wavelength of 530nm and comparing the absorbance with a standard curve to obtain the concentration of nitrate in the solution to be detected.
7. The method for using a nitrate detection reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride according to claim 6, wherein: the acid solution is sulfuric acid.
8. Vegetables nitrate nitrogen detects box, its characterized in that: nitrate nitrogen detecting reagent containing 3-methyl-2-benzothiazolinone hydrazone hydrochloride according to any one of claims 1 to 5.
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| CN117007788A (en) * | 2023-08-03 | 2023-11-07 | 中拓生物有限公司 | Nitric oxide determination kit and preparation method and application thereof |
| CN117007788B (en) * | 2023-08-03 | 2024-03-19 | 中拓生物有限公司 | Nitric oxide determination kit and preparation method and application thereof |
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Application publication date: 20220830 |