CN111965180A - Quantitative detection method for alkyl nitrate in diesel oil - Google Patents
Quantitative detection method for alkyl nitrate in diesel oil Download PDFInfo
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- CN111965180A CN111965180A CN202010891601.1A CN202010891601A CN111965180A CN 111965180 A CN111965180 A CN 111965180A CN 202010891601 A CN202010891601 A CN 202010891601A CN 111965180 A CN111965180 A CN 111965180A
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Abstract
The invention discloses a quantitative detection method of alkyl nitrate in diesel oil, and relates to the technical field of quantitative detection of cetane number improvers in diesel oil. It includes: placing the first solution obtained after hydrolysis reaction of diesel oil to be detected and sulfuric acid solution in a chromatographic device filled with silica gel, when the first solution obtained after hydrolysis reaction passes through a silica gel layer in the chromatographic device, displaying a dyeing layer on the silica gel layer, and determining the color development amount of the chromatographic device according to the length or volume of the dyeing layer. The method realizes the quantitative detection of the alkyl nitrate by utilizing the hydrolysis reaction of organic nitrates under the acidic condition and the oxidation reaction of identifying nitrate by diphenylamine under the acidic condition. The method greatly simplifies the test operation steps of quantitative detection of the alkyl nitrate, and reduces the use amount of toxic and harmful reagents and corrosive reagents in the test process. The quantitative detection method provided by the invention does not need measuring instruments and equipment, and greatly saves the cost of analysis and detection.
Description
Technical Field
The invention relates to the technical field of quantitative detection of cetane number improvers in diesel oil, and particularly relates to a quantitative detection method of alkyl nitrate in diesel oil.
Background
Alkyl nitrates, which are a classic cetane improver and whose explosiveness is inversely proportional to their molecular weight, are better able to improve combustion efficiency because they thermally decompose to give more free radicals. Alkyl nitrates are predominant in the market because of their good cetane number improvement effect and low price. Research shows that the addition of alkyl nitrate can affect the color and stability of diesel oil for automobile.
At present, ultraviolet spectrophotometry is mainly adopted in the quantitative method of alkyl nitrate in vehicle diesel oil, such as SH/T0553 + 1993, ASTM D4046-2014 and ISO 13579 + 1996, and the determination principle is that alkyl nitrate in a sample is hydrolyzed in sulfuric acid solution to generate nitric acid, then m-dimethylphenol is added to carry out nitration reaction with the nitric acid generated by hydrolysis, generated nitrophenol is extracted from a nitration reaction mixture by isooctane, the nitrophenol reacts with sodium hydroxide to obtain yellow phenol sodium salt, the absorbance is determined at the wavelength of 452nm, and the content of the alkyl nitrate is calculated according to the slope of a standard working curve.
The existing method for quantifying the alkyl nitrate has the following defects: firstly, the operation steps of standard solution preparation and sample pretreatment reaction extraction are complicated, and the manual operation treatment period is long; and secondly, m-dimethylphenol with strong toxicity and strong volatility is required to be used in the step of sample pretreatment, reaction and extraction, and the existing detection method is not green and friendly to operators and experimental environment.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a quantitative detection method for alkyl nitrate in diesel oil to solve the technical problem.
The invention is realized by the following steps:
a quantitative detection method for alkyl nitrate in diesel oil comprises the following steps: placing a first solution obtained after hydrolysis reaction of diesel oil to be detected and a sulfuric acid solution in a chromatographic device filled with silica gel, when the first solution obtained after hydrolysis reaction passes through a silica gel layer in the chromatographic device, displaying a dyeing layer on the silica gel layer, and determining the color development amount of the chromatographic device according to the length or volume of the dyeing layer; then substituting the color development amount of the diesel oil to be detected in a chromatographic device into a standard curve to determine the content of the alkyl nitrate in the diesel oil to be detected; the standard curve is a standard curve of the concentration of the alkyl nitrate standard solution and the color development amount of the chromatographic device;
diphenylamine is loaded on the surface of the silica gel.
The invention provides a simple and feasible quantitative detection method for alkyl nitrate in diesel oil. The quantitative detection of the alkyl nitrate is realized by utilizing the hydrolysis reaction of organic nitrates under the acidic condition and the oxidation reaction of diphenylamine identifying nitrate under the acidic condition.
Alkyl nitrates are hydrolyzed in sulfuric acid solution to form nitrate ions, and the nitrate ions oxidize diphenylamine to blue or blue-black quinoid compounds under acidic conditions, the chemical reaction formula of which is as follows, and the hydrolysis reaction equation of isooctyl nitrate and the oxidation reaction equation of nitrate and diphenylamine are shown as follows:
hydrolysis reaction of isooctyl nitrate:
oxidation reaction of diphenylamine:
and (2) introducing the reaction solution after the hydrolysis reaction into a chromatographic device filled with silica gel, when the reaction solution passes through a silica gel layer, oxidizing diphenylamine by using nitrate radicals in the solution to generate blue or bluish-black precipitates, so that a dyed layer with a certain length is shown on the silica gel layer, determining a standard curve equation according to the length (or volume) of the dyed silica gel and the content of the alkyl nitrate in the chromatographic device, hydrolyzing a sample to be detected, introducing the hydrolyzed sample into the chromatographic device filled with the silica gel to obtain the length or volume of the dyed layer, and substituting the length or volume of the dyed layer into the standard curve to calculate and obtain the content of the alkyl nitrate in the sample.
Diphenylamine was supported on the surface of silica gel, and quantitative detection of alkyl nitrate was performed using a chromatography device filled with silica gel.
In a preferred embodiment of the present invention, the quantitative determination method comprises preparing silica gel with diphenylamine loaded on the surface, preferably, loading diphenylamine on the surface of the silica gel by an impregnation method.
In other embodiments of the present invention, the loading diphenylamine on the surface of the silica gel by the impregnation method comprises the following steps: and (3) soaking the silica gel in a diphenylamine solution containing sulfuric acid for 2-5 h.
The diphenylamine solution is a glacial acetic acid solution containing diphenylamine, and the concentration of diphenylamine in the glacial acetic acid solution is 5-100 g/L; the content of sulfuric acid in the diphenylamine solution is 0.09M-2M.
In other embodiments, the diphenylamine solution may alternatively be dissolved in other organic acid solvents, such as propionic acid.
In the preferred embodiment of the present invention, the mass of the impregnated silica gel per liter of diphenylamine solution is 10-1000 g.
And (3) drying the impregnated silica gel in an oven until the water content of the silica gel is 25-30%, and preferably, the temperature of the oven is 70 +/-5 ℃.
Diphenylamine is loaded on the surface of the silica gel in an impregnation mode, and the impregnated silica gel can meet the oxidation reaction carrier of diphenylamine under an acidic condition by being impregnated in a diphenylamine solution containing sulfuric acid. The uniform load of diphenylamine on the surface of the silica gel can be effectively realized within 2-5 h.
When diphenylamine is loaded on the surface of the silica gel, the loading effect is best when the content of sulfuric acid in the diphenylamine solution is in the range of 0.09-2M. Glacial acetic acid is used as a solvent of diphenylamine, so that the dispersion uniformity of diphenylamine can be improved.
The mass of the silica gel impregnated in each liter of diphenylamine solution is not suitable to be too large, and when the mass of the silica gel in each liter of diphenylamine solution exceeds 1000g, the surface of the silica gel is easily insufficiently impregnated, so that the diphenylamine loading success rate of the silica gel is reduced, and the content of alkyl nitrate in a subsequent oxidation reaction sample cannot be truly realized.
In other embodiments, the temperature of the oven may also be adaptively adjusted as desired.
In a preferred embodiment of the present invention, before loading diphenylamine on the surface of the silica gel, the silica gel is further activated.
In a preferred embodiment of the present invention, the activating treatment of the silica gel comprises: soaking silica gel in acid solution, washing with water to neutrality, and drying.
The acid solution is a hydrochloric acid solution with the mass fraction of 19%, and the soaking time is 1-4 h; preferably, the silica gel washed to be neutral by water is dried at the temperature of 100-130 ℃.
The silica gel is activated through the activation treatment of the silica gel, so that the success rate of silica gel loading is greatly improved.
The moisture and the surface volatile matter adsorbed on the surface of the silica gel are removed by drying, so that the groups on the surface of the silica gel are uniformly dispersed, and the next reaction is conveniently carried out.
The acidic and basic properties of the silica gel are adjusted by an acidic solution, so that the silica gel is easier to load with diphenylamine.
The standard curve is drawn by: and placing the second solution obtained after the hydrolysis reaction of the alkyl nitrate standard solution and the sulfuric acid solution in a chromatographic device filled with silica gel, displaying a dyeing layer on the silica gel layer when the second solution obtained after the hydrolysis reaction passes through the silica gel layer in the chromatographic device, determining the color development amount of the chromatographic device according to the length or the volume of the dyeing layer, and drawing a standard curve according to the concentration of the alkyl nitrate standard solution and the color development amount of the chromatographic device.
The standard curve can be drawn according to the detection requirement.
In a preferred embodiment of the present invention, the chromatographic device is a graduated chromatographic tube or column; preferably, the chromatography tube or column has a structure with a wide top and a narrow bottom.
In some embodiments of the invention, the silica gel has a particle size of 40-80 mesh.
In some embodiments of the invention, the scale has a minimum division of less than 1 mL; the minimum scale division of the scale is 0.02 mL.
In a preferred embodiment of the present invention, the quantitative detection method comprises filling silica gel with diphenylamine loaded on the surface thereof into the chromatography device, and controlling the height of the silica gel layer to be flush with the scale mark.
By marking scales, detection personnel can directly quantify according to the volume or the length of the color development layer in the chromatography device. The defects that the operation steps of the existing sample activation treatment reaction extraction are complex and the manual operation treatment period is long are overcome, the workload of experimenters is greatly reduced, and the difficulty of quantitative analysis and detection is reduced.
In a preferred embodiment of the present invention, the alkyl nitrate standard solution is prepared by diluting alkyl nitrate with diesel oil.
In some embodiments of the invention, the volume fraction of alkyl nitrate to the alkyl nitrate standard solution is: 0.050% -0.200%.
In some embodiments of the invention, the alkyl nitrate is at least one of 2-ethylhexyl nitrate, cyclohexyl nitrate, isooctyl nitrate, n-butyl nitrate, cyclododecyl nitrate, 3-tetrahydrofuran nitrate, glycerol trinitrate, and tetraethyleneglycol dinitrate.
The alkyl nitrate is diluted by diesel oil to prepare an alkyl nitrate standard solution, and other solvents are not selected for dilution, so that a more accurate standard curve can be drawn, and the measurement error of the content of the alkyl nitrate in a sample is smaller.
At present, the volume fraction of the added alkyl nitrate in the diesel oil is 0.050-0.200%, and the detection method provided by the invention can completely cover the existing detection range of the added amount of the alkyl nitrate.
It should be noted that the detection method provided by the present invention is not limited to the quantitative detection of the alkyl nitrate, and in other embodiments, the alkyl nitrate may be adaptively adjusted as needed.
In a preferred embodiment of the present invention, when the sulfuric acid solution and the standard solution of diesel oil or alkyl nitrate to be measured perform hydrolysis reaction, the volume ratio of the sulfuric acid solution to the standard solution of diesel oil or alkyl nitrate to be measured as a reactant is 4: 1-2.
In some embodiments of the invention, the sulfuric acid solution is a hydrolysis sulfuric acid.
In some embodiments of the invention, the concentration of sulfuric acid for hydrolysis is 8-14M.
In some embodiments of the invention, the diesel fuel to be tested is automotive diesel fuel.
In order to ensure that the alkyl nitrate in the diesel oil to be detected is fully hydrolyzed, the volume of the sulfuric acid solution provided by the invention is far larger than that of the liquid to be detected or the standard liquid.
In a preferred embodiment of the present invention, the hydrolysis reaction is performed in a separatory funnel, and the first solution in the lower layer is placed in a chromatographic apparatus containing silica gel after the reaction.
In a preferred embodiment of the present invention, the dyed layer is blue or blue-black.
Nitrate ions can oxidize diphenylamine to blue or blue-black quinoid compounds under acidic conditions.
The invention has the following beneficial effects:
the invention provides a quantitative detection method of alkyl nitrate in diesel oil. The method realizes the quantitative detection of the alkyl nitrate by utilizing the hydrolysis reaction of organic nitrates under the acidic condition and the oxidation reaction of identifying nitrate by diphenylamine under the acidic condition. The method greatly simplifies the test operation steps of quantitative detection of the alkyl nitrate, and reduces the use amount of toxic and harmful reagents and corrosive reagents in the test process. The quantitative detection method provided by the invention does not need measuring instruments and equipment, and greatly saves the cost of analysis and detection.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a flow chart of quantitative determination of alkyl nitrate in diesel oil according to example 2.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
The embodiment provides a quantitative detection method for alkyl nitrate in diesel oil. Which comprises the following steps:
(1) preparation of the impregnated silica gel:
soaking silica gel with a particle size of 40-50 meshes in a hydrochloric acid solution with a mass fraction of 19% for 2h, washing with tap water, washing with distilled water to neutrality, and drying at 120 ℃.
1.5g of diphenylamine was accurately weighed and dissolved in a beaker containing 100mL of glacial acetic acid, and then 1.5mL of concentrated sulfuric acid was added and stirred uniformly. Then 80g of dried silica gel is added, fully stirred and soaked for 3 h. Then the impregnated silica gel is put into an oven with the temperature of 70 +/-5 ℃ and stirred once every 30min until the water content of the impregnated silica gel is 25 percent.
After cooling from the oven, the impregnated silica gel was loaded into a 2mL glass reaction tube and tapped down to the scale.
The glass reaction tube used in this example had a thick upper portion and a thin lower portion, and had graduations at the lower portion, with a minimum graduation of 0.02mL and a maximum graduation of at least 2mL, and had a porous glass partition plate provided on the end face of the lower portion. The lower narrow tube was filled with 2mL of coarse pore impregnated silica gel.
(2) Drawing a standard curve:
in this embodiment, the content of isooctyl nitrate (nitrate) in diesel oil for vehicles is selectively detected, 5.00mL of isooctyl nitrate is absorbed and added into a 100mL volumetric flask, the diesel oil for vehicles is diluted to a scale mark to prepare isooctyl nitrate standard solution with the concentration of 5% (V/V), then a pipette is used to accurately transfer 0.5, 1.0, 2.0, 3.0 and 4.0mL of the isooctyl nitrate solution with the concentration of 5% into four 100mL volumetric flasks respectively, and the diesel oil for vehicles is diluted to the scale mark respectively to prepare isooctyl nitrate standard working solution with the concentration of 0.025% -0.200% (V/V).
The test was carried out according to the test procedure shown in FIG. 1, and the color development volume in the glass reaction tube was measured.
Accurately transferring 10mL of isooctyl nitrate standard working solution into a 125mL separating funnel added with 40mL of hydrolysis sulfuric acid solution, screwing a plug of the separating funnel, shaking the separating funnel to ensure that the sample solution and the hydrolysis sulfuric acid solution are uniformly mixed, then placing the separating funnel on a Kangshi shaking machine to shake for 30min, standing after shaking is finished, collecting lower-layer acid solution, and injecting the lower-layer acid solution into a glass reaction tube filled with impregnated silica gel.
The nitrate ion reacts with diphenylamine in the impregnated silica gel to generate a blue-black precipitate for color development, and the color development volume is measured.
The relationship between the content of alkyl nitrate in various concentrations and the color development volume of the reaction tube is shown in Table 1:
table 1 colour volume in glass reaction tubes as a function of alkyl nitrate concentration.
2) And (3) sample determination: accurately transferring 10mL of vehicle diesel oil sample (purchased from a gas station) into a 125mL separating funnel added with 40mL of hydrolysis sulfuric acid solution, screwing down a plug of the separating funnel, shaking the separating funnel to ensure that the sample solution and the hydrolysis sulfuric acid solution are uniformly mixed, then placing the separating funnel on a Kangshi shaking machine to shake for 30min, standing after the shaking is finished, collecting lower-layer acid solution, and injecting the lower-layer acid solution into a glass reaction tube filled with impregnated silica gel.
The color developing volume in the glass reaction tube was 0.44mL, and the volume fraction of the alkyl nitrate in the sample was 0.057% based on the volume fraction of the alkyl nitrate of 0.129 × the color developing volume.
In this example, a sulfuric acid solution was used to hydrolyze alkyl nitrate, and the preparation method of the sulfuric acid solution for hydrolysis was: 500mL of concentrated sulfuric acid was slowly added to 270mL of cold water with stirring by a glass rod.
Example 2
The embodiment provides a quantitative detection method for alkyl nitrate in diesel oil. Which comprises the following steps:
(1) preparation of the impregnated silica gel:
soaking silica gel with the particle size of 60-80 meshes in a hydrochloric acid solution with the mass fraction of 19% for 3h, washing with tap water, washing with distilled water to be neutral, and drying at 100 ℃.
1.5g of diphenylamine was accurately weighed and dissolved in a beaker containing 100mL of glacial acetic acid, and then 1.5mL of concentrated sulfuric acid was added and stirred uniformly. Then 100g of dried silica gel is added, fully stirred and soaked for 3 h. Then the impregnated silica gel is put into an oven with the temperature of 70 +/-5 ℃ and stirred once every 30min until the water content of the impregnated silica gel is 25 percent.
After cooling from the oven, the impregnated silica gel was loaded into a 2cm long glass reaction chromatography column and tapped down to the scale.
The glass reaction tube used in this example has a thick upper part and a thin lower part, the lower part has graduations, the minimum graduation is 0.1cm, the maximum graduation is at least 2cm, and the end face of the lower part is provided with a porous glass partition plate. The lower thin tube is filled with 2cm of coarse-pore impregnated silica gel.
(2) Drawing a standard curve:
in this embodiment, the content of isooctyl nitrate in diesel oil for vehicles is selectively detected, 5.00mL of isooctyl nitrate is absorbed and added into a 100mL volumetric flask, the diesel oil for vehicles is diluted to scale marks to prepare isooctyl nitrate standard solution with the concentration of 5% (V/V), then 0.5, 1.0, 2.0, 3.0 and 4.0mL of the isooctyl nitrate solution with the concentration of 5% are accurately transferred by a pipette and respectively added into four 100mL volumetric flasks, and the diesel oil for vehicles is respectively diluted to scale marks to prepare isooctyl nitrate standard working solution with the concentration of 0.025% -0.200% (V/V).
The test was carried out according to the test procedure shown in FIG. 1, and the color development volume in the glass reaction tube was measured.
Accurately transferring 10mL of isooctyl nitrate standard working solution into a 125mL separating funnel added with 40mL of hydrolysis sulfuric acid solution, screwing a plug of the separating funnel, shaking the separating funnel to ensure that the sample solution and the hydrolysis sulfuric acid solution are uniformly mixed, then placing the separating funnel on a Kangshi shaking machine to shake for 30min, standing after shaking is finished, collecting lower-layer acid solution, and injecting the lower-layer acid solution into a glass reaction chromatographic column filled with impregnated silica gel.
The nitrate ion reacts with diphenylamine in the impregnated silica gel to generate a blue-black precipitate for color development, and the color development length is measured.
The relationship between the content of alkyl nitrate in various concentrations and the color development volume of the reaction tube is shown in Table 2.
Table 2 colour volume in glass reaction tubes as a function of alkyl nitrate concentration.
2) And (3) sample determination: accurately transferring 10mL of vehicle diesel oil sample to be tested into a 125mL separating funnel added with 40mL of hydrolysis sulfuric acid solution, screwing down a plug of the separating funnel, shaking the separating funnel to ensure that the sample solution and the hydrolysis sulfuric acid solution are uniformly mixed, then placing the separating funnel on a Kangshi shaking machine to shake for 30min, standing after shaking is finished, collecting lower-layer acid solution, and injecting the lower-layer acid solution into a glass reaction tube filled with impregnated silica gel.
The color development volume in the glass reaction column was 0.55cm, and the volume fraction of the alkyl nitrate in the sample was 0.079% as shown by 0.1431 × the color development length.
In this example, a sulfuric acid solution was used to hydrolyze alkyl nitrate, and the preparation method of the sulfuric acid solution for hydrolysis was: 500mL of concentrated sulfuric acid was slowly added to 270mL of cold water with stirring by a glass rod.
Comparative example 1
This comparative example employed conventional UV spectrophotometry for quantitative determination of alkyl nitrate of the sample to be tested in example 1. The volume fraction of alkyl nitrate in the sample of example 1 was determined to be 0.053% according to the experimental procedure of standard SH/T0559.
Compared with the chromatography in the embodiment 1 of the invention, the volume fractions of the alkyl nitrate in the samples are similar, and the results are matched, which shows that the layer washing method provided by the embodiment 1 of the invention is reliable.
Comparative example 2
This comparative example provides a diesel fuel with a known volume fraction of alkyl nitrate of 0.080% (diesel fuel was tested using the test method provided in example 2). Example 2 the volume fraction of alkyl nitrate detected in the vehicle diesel was 0.079%.
The volume fraction of alkyl nitrate in the sample was determined to be similar to known results, indicating that the layer wash method provided in example 2 of the present invention is reliable.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A quantitative detection method for alkyl nitrate in diesel oil is characterized by comprising the following steps: placing a first solution obtained after hydrolysis reaction of diesel oil to be detected and a sulfuric acid solution in a chromatographic device filled with silica gel, when the first solution obtained after hydrolysis reaction passes through a silica gel layer in the chromatographic device, displaying a dyeing layer on the silica gel layer, and determining the color development amount of the chromatographic device according to the length or volume of the dyeing layer; then substituting the color development amount of the diesel oil to be detected in a chromatographic device into a standard curve to determine the content of the alkyl nitrate in the diesel oil to be detected; the standard curve is a standard curve of the concentration of the alkyl nitrate standard solution and the color development amount of the chromatographic device;
diphenylamine is loaded on the surface of the silica gel.
2. The quantitative determination method according to claim 1, wherein the quantitative determination method comprises preparing a silica gel having diphenylamine supported on the surface thereof, preferably by a dipping method.
3. The quantitative determination method according to claim 2, wherein the loading of diphenylamine on the surface of the silica gel by the dipping method comprises the steps of: soaking silica gel in diphenylamine solution containing sulfuric acid for 2-5 h;
preferably, the diphenylamine solution is a glacial acetic acid solution containing diphenylamine, and the concentration of diphenylamine in the glacial acetic acid solution is 5-100 g/L; the content of sulfuric acid in the diphenylamine solution is 0.09M-2M;
preferably, the mass of the impregnated silica gel per liter of the diphenylamine solution is 10-1000 g;
preferably, the impregnated silica gel is dried in an oven until the water content of the silica gel is 25-30%, and the temperature of the oven is 70 +/-5 ℃.
4. The quantitative determination method of claim 1, wherein the plotting of the standard curve comprises: and placing the second solution obtained after the hydrolysis reaction of the alkyl nitrate standard solution and the sulfuric acid solution in a chromatographic device filled with silica gel, displaying a dyeing layer on the silica gel layer when the second solution obtained after the hydrolysis reaction passes through the silica gel layer in the chromatographic device, determining the color development amount of the chromatographic device according to the length or the volume of the dyeing layer, and drawing a standard curve according to the concentration of the alkyl nitrate standard solution and the color development amount of the chromatographic device.
5. The quantitative determination method according to claim 1, wherein the chromatographic device is a chromatography tube or a chromatography column labeled with scales; preferably, the chromatography tube or the chromatography column is of a structure with a wide top and a narrow bottom;
preferably, the particle size of the silica gel is 40-80 meshes;
preferably, the minimum division of the scale is less than 1 mL; preferably, the minimum division of the scale is 0.02 mL;
preferably, the quantitative detection method comprises the steps of filling silica gel with diphenylamine loaded on the surface into the chromatography device, and controlling the height of the silica gel layer to be flush with the scale mark.
6. The quantitative determination method according to claim 5, characterized by further comprising an activation treatment of the silica gel before the loading of diphenylamine on the surface of the silica gel;
preferably, the activation treatment of the silica gel comprises: soaking silica gel in an acid solution, then washing with water to be neutral, and drying;
preferably, the acid solution is hydrochloric acid, and the soaking time is 1-4 h; preferably, the silica gel washed to be neutral by water is dried at the temperature of 100-130 ℃.
7. The quantitative determination method according to claim 1, wherein the alkyl nitrate standard solution is an alkyl nitrate standard solution prepared by diluting an alkyl nitrate with diesel oil; preferably, the volume fraction of the alkyl nitrate to the alkyl nitrate standard solution is: 0.050% -0.200%;
preferably, the alkyl nitrate is at least one of 2-ethylhexyl nitrate, cyclohexyl nitrate, isooctyl nitrate, n-butyl nitrate, cyclododecyl nitrate, 3-tetrahydrofuran nitrate, glycerol trinitrate, and tetraethyleneglycol dinitrate.
8. The quantitative determination method according to claim 7, wherein when the sulfuric acid solution is hydrolyzed with the diesel oil or alkyl nitrate standard solution to be determined, the volume ratio of the sulfuric acid solution to the diesel oil or alkyl nitrate standard solution to be determined is 4: 1-2; preferably, the sulfuric acid solution is sulfuric acid for hydrolysis; preferably, the concentration of the sulfuric acid for hydrolysis is 8-14M;
preferably, the diesel oil to be tested is vehicle diesel oil.
9. The quantitative determination method of claim 8, wherein the hydrolysis reaction is performed in a separatory funnel, and after the reaction, the lower layer of the first solution is placed in a chromatographic apparatus containing silica gel.
10. The quantitative determination method of claim 1, wherein the dyed layer is blue or bluish-black.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112577921A (en) * | 2020-12-17 | 2021-03-30 | 中国石油化工股份有限公司 | Method for detecting alkyl nitrate |
| CN114088694A (en) * | 2021-10-21 | 2022-02-25 | 包头钢铁（集团）有限责任公司 | Method for rapidly determining content of hydrogen sulfide in wastewater |
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| CN114088694A (en) * | 2021-10-21 | 2022-02-25 | 包头钢铁（集团）有限责任公司 | Method for rapidly determining content of hydrogen sulfide in wastewater |
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