CN112461628A - Oil product salt content integrated batch pretreatment and sampling method - Google Patents
Oil product salt content integrated batch pretreatment and sampling method Download PDFInfo
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Abstract
The invention discloses an integrated batch pretreatment and sampling method for salt content of an oil product, relating to the technical field of analytical chemistry.A certain amount of the oil product to be treated is weighed in a 50mL centrifuge tube with a conical bottom and a cover, a diluent is added and mixed uniformly, an extract liquid is added, and a plurality of drops of hydrogen peroxide are added; placing a sampling device into a centrifugal tube, wherein the sampling device is specifically composed of an upper funnel and a vertical sampling channel communicated with the bottom of the funnel, and the end of the channel is sealed by a membrane; screwing the tube cover to compact the flanging at the outer edge of the top end of the funnel and simultaneously sealing the centrifuge tube; a plurality of centrifuge tubes are uniformly and symmetrically placed in a sleeve of a sample disc of the constant-temperature shaking and centrifuging all-in-one machine for fixation, and are subjected to shaking extraction and centrifugal layering; the tube cap is screwed off, the long needle connected with the syringe is inserted into the sampling channel and pierces the film, the solution under the oil layer is extracted for detection and calculation, and the salt content of the oil product is expressed by mgNaCl/L. The invention can simultaneously pretreat a plurality of oil products, has high and stable extraction rate, takes the solution under the oil layer without oil, and can be directly matched with a plurality of detection methods for analysis.
Description
Technical Field
The invention relates to the technical field of analytical chemistry, in particular to a centrifugal tube for detecting the salt content of an oil product and an integrated batch pretreatment method for detecting the salt content of the oil product.
Background
The salt content of crude oil is generally defined as sodium chloride, magnesium chloride and calcium chloride and other inorganic chlorides dissolved in crude oil, and the results of inorganic chlorides are all expressed in terms of the amount of sodium chloride (mgNaCl/L). The standard method widely applied to the measurement of the salt content of the oil product in the domestic oil refining industry at present is SY/T0536-2008, the measurement of the salt content in the crude oil (an electric quantity method); the principle is that crude oil is heated in the presence of a polar solvent, salt contained in the crude oil is extracted by alcohol water, an appropriate amount of extract is extracted by an injector after centrifugal separation and injected into acetic acid electrolyte containing a certain amount of silver ions, chloride ions in a sample are subjected to precipitation reaction with the silver ions, and consumed silver ions are supplemented by generation electrode electricity. The amount of chlorine ions in the extract converted into sodium chloride can be obtained by measuring the electric quantity consumed by the electrogenerated silver ions according to the Faraday's law.
The GB/T6532-2012 method is that the oil sample is preheated and uniformly mixed on a water bath with the temperature of about 65 ℃, xylene is preheated at the same time, and the oil product is diluted and dissolved and transferred into a flask through a liquid adding funnel; washing the beaker and the liquid adding funnel with ethanol and acetone respectively, and transferring the solution to the flask; heating until the solution boils for 2min, stopping heating, washing with deionized water, and transferring the solution to a flask; heating to boil for 15min, cooling and layering; the aqueous phase is discharged from the lower piston. The Cl-ions in the extract were quantified by potentiometric titration with silver nitrate. After manual high-frequency oscillation extraction, anions are subjected to organic removal in a certain mode, such as a column switching mode, interference of ethanol and possible oil stains in the extraction liquid on an ion chromatographic system is eliminated, and then inorganic chloride is separated and analyzed through an ion chromatographic column, so that the analysis requirement of the salt content in the crude oil can be met.
No matter the method for measuring the salt content in the crude oil is SY/T0536-2008 or GB/T6532-2012, and the newly developed oil product salt content analysis method such as ion chromatography, the pretreatment process of the oil product is complicated. Compared with the GB/T6532-;
however, SY/T0536-2008, the coulometry method for the salt content in crude oil still has some places needing improvement, such as a complicated sample pretreatment process: firstly, carrying out fussy semi-manual high-frequency oscillation liquid-liquid extraction, heating an oil sample to be detected to 50-70 ℃, shaking the oil sample evenly, putting 1.0g +/-0.1 g of the oil sample into a centrifuge tube, adding 1.5mL of dimethylbenzene and 2mL of ethanol water (volume ratio is 1: 3), heating for 1min under the condition of water bath at 60-70 ℃, rapidly oscillating and mixing for 1min by using a vortex high-frequency oscillator, repeating the heating and mixing processes again, then putting the mixture into a centrifuge for centrifugation for 2min, layering oil and water phases, taking out a lower-layer water phase by using an injector for analysis, wherein the salt content extraction rate is unstable or low due to manual participation; secondly, sulfide can interfere the determination of the content of the salt by an electric quantity method, and chloride really causes the corrosion problem of equipment; in the secondary determination process, the change of the conversion rate is influenced by the stability of the microcoulometer, and the electrolyte may need to be repeatedly replaced in the experimental process to wash the electrolytic cell; finally, the sampling amount is smaller and is only 1.0g, and the sampling representativeness requirement is higher.
In particular, the above-mentioned 3 oil product salt content detection methods are sensitive to oil contamination in the extraction liquid, and greatly affect the accuracy and parallelism of the salt content result. How to cleanly obtain the extraction liquid taking the hydroalcoholic at the lower layer of the oil layer of the centrifugal tube as a main body, the design of the centrifugal tube and a sampling method suitable for the centrifugal tube are key; meanwhile, in view of the fact that the existing oil product salt content method is to pretreat single oil samples one by one, the realization of batch oil sample pretreatment is urgent.
At present, in a QuEChERS automatic sample preparation system in the process of food and biological extracts at home and abroad, the integration of the oscillation and the centrifugation functions is realized by adopting a stepping motor, and the method for realizing the oscillation is that the stepping motor is used as a driving source to reciprocate with certain frequency and amplitude; the centrifugal force is realized by unidirectional rotation. The mode can only realize the vibration on the same plane, the frequency and the angle of the mode are obviously limited by the performance of the stepping motor, and the vibration is often insufficient; in addition, the stepping motor has small loading capacity and slow unidirectional rotation speed, so that the requirement of sample preparation analysis cannot be completely met in centrifugal rotation speed, and the stepping motor is particularly used for integrated batch pretreatment of oil product salt content detection and has no report.
Documents closely related to the present invention:
first embodiment CN105115809b an analysis sample preparation apparatus and an analysis sample preparation method. The invention provides a novel device for coupling the shaking and the centrifugation, which can realize the coupling of the shaking and the centrifugation in the same mechanical device and obviously improve the efficiency.
And the materials in petroleum refining and chemical engineering, 2013 and 44 (10): 97-100. The research of a batch analysis method of the salt content in the crude oil. Based on the SY/T0536-; and the mixing extraction and centrifugal stratification cannot be performed on the same device.
Disclosure of Invention
The invention aims to overcome the pretreatment in the determination of the salt content of the crude oil (oil product), namely the complicated semi-manual high-frequency shaking liquid-liquid extraction, realize the integration, the sealing, the automation and the batch of the pretreatment of samples such as the constant temperature, the shaking and the centrifugal extraction of the salt content of the crude oil (oil product), reduce the labor intensity and eliminate the potential safety hazard; and solve the problem that the lower water alcohol extraction solution of the oil layer needs to be extracted by an electrolytic cell or a chromatographic column without oil stain pollution; and the problem of low representative deficiency possibly caused by small sampling amount of the SY/T0536-2008 method, and the salt content extraction rate is further stably improved through the new extraction liquid formula, so that a foundation is laid for improving the analysis accuracy of subsequent different salt content detection methods.
The invention is realized by the following technical scheme:
the invention provides a centrifuge tube for detecting the salt content of an oil product and an integrated batch pretreatment method, wherein the method specifically comprises the following steps:
step 1, quantitatively putting an oil product to be treated into a 50mL centrifuge tube with a conical bottom and a cover, adding a dimethyl benzene diluent, uniformly mixing, adding an extract liquid, dropping hydrogen peroxide, putting a sampling device into the centrifuge tube, screwing a tube cover to seal the centrifuge tube, and fixing the sampling device to obtain the oil product centrifuge tube to be treated;
wherein: the sampling device is composed of a funnel with a flanging at the top end outer edge and a sampling channel communicated with the bottom of the funnel, wherein the inner diameter of the flanging is smaller than the inner diameter of the top end of the centrifugal tube, the outer diameter of the flanging is larger than the inner diameter of the centrifugal tube and not larger than the outer diameter of the centrifugal tube, the end of the sampling channel is sealed by a thin film, and the sealing film is not contacted with the inner wall of the centrifugal tube when the sampling device is arranged in;
step 2, repeating the step 1 to prepare a plurality of oil centrifugal tubes to be treated, uniformly and symmetrically placing the plurality of oil centrifugal tubes to be treated in a sample disc sleeve of the constant-temperature shaking and centrifuging all-in-one machine for fixation, and performing shaking extraction and centrifugal layering; after the completion, the tube cap is screwed off, a 12mm long needle connected with an injector is inserted into the sampling channel and pierces the sealing membrane, the solution under the oil layer is extracted for detection, potentiometric titration or microcoulometric titration or ion chromatography is carried out to measure the chloride ion content, and finally the salt content of the oil product expressed by mgNaCl/L is calculated.
Further, centrifuging tube and tube cap are made by chlorine-free material high density polypropylene PP, sampling device specifically is made by chlorine-free material low density polyethylene, when sampling device fixes in the centrifuging tube, the bottom of the seal membrane is less than or equal to 0.5cm from the bottom of the core tube.
Further, the extract is water and ethanol in a volume ratio of 3:1, and contains 100-200 mmol/L of chlorine-free demulsifier and 50-100 mmol/L of citric acid or acetic acid, the dosage of the extract is 10-16 mL, the dosage of hydrogen peroxide is 8-16 drops, the dosage of xylene is 7.5-12 mL, and the oil quality is 5-8 g.
Further, the constant-temperature shaking and centrifuging all-in-one machine is formed by adding a temperature rise control and control device to a QuEChERS automatic sample preparation system, and is used for centrifuging and layering. The specific process is that the constant temperature range is 60-80 ℃, the shaking time is 5-10 min, the shaking amplitude is 23-25 mm, the shaking frequency is 1000-1100 Hz, the centrifugal speed is 4000-4500 rpm, and the centrifugal time is 5-10 min.
Compared with the prior art, the invention has the following advantages:
1. the shaking and centrifugal coupling are realized in the same mechanical device, the preparation process of the oil sample is obviously simplified compared with manual operation, and batch pretreatment is realized, so that the stability is high, and the operation is convenient and fast;
2. the centrifugal tube for oil salt content is innovatively designed, so that the extraction is convenient, the extraction liquid below the oil layer is free from oil stain pollution, and the pollution and interference of potentiometric titration, microcoulomb coulometric titration or ion chromatography detection are eliminated.
3. The new extract is composed of a chlorine-free demulsifier and acetic acid or citric acid added into an alcohol-water mixed solution of a standard method, wherein the specific volume ratio of water to ethanol is 3:1, 100-200 mmol/L of the chlorine-free demulsifier and 50-100 mmol/L of the acetic acid or citric acid are contained, the extraction rate of inorganic salts such as chloride is improved by more than 99 percent from about 95 percent, and the extraction is stable and is easier to layer;
4. the salt content extraction mode is based on SY/T0536-2008, but the sampling amount is 3-6 times of that of the salt content extraction mode, and the representativeness of the sample is stronger;
5. the oil product shaking coupling centrifugation integrated liquid-liquid extraction mode is adopted to couple the oil product shaking coupling centrifugation integrated liquid-liquid extraction mode and the liquid-liquid extraction mode in the same mechanical device, so that the preparation process of an analysis sample can be greatly simplified, the working efficiency is greatly improved, and batch pretreatment is realized.
Compared with a high-frequency shaking-centrifugate liquid-liquid semi-manual mixed extraction and stepped high-speed centrifugation layering pretreatment and sampling method of SY/T0536, the oil product salt content integrated batch pretreatment and sampling method of the invention has consistent detection results and better precision.
Drawings
FIG. 1 is a schematic flow chart of the method described in the examples.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example (b):
the invention provides an integrated batch pretreatment and sampling method for oil salt content, wherein a diluent is dimethylbenzene, an extract liquid is water and ethanol with the volume ratio of 3:1, contains 100-200 mmol/L of chlorine-free demulsifier and 50-100 mmol/L of acetic acid or citric acid, the heating and constant temperature time, the shaking frequency, the amplitude and the time, and the centrifugal speed and the centrifugal time are controlled by programs and are automatically adjusted and set, so that the integration, the batch and the automation of the pretreatment of the oil salt content analysis are realized, and the treatment quantity of one sample is 3-12; after being combined and loaded, a self-made 50mL centrifuge tube with a conical bottom and a cover and a sampling device are uniformly and symmetrically placed on a sample tray of a constant-temperature shaking and centrifuging all-in-one machine for fixation; after shaking and centrifuging at constant temperature, layering the oil product solution and the extract solution; screwing off the tube cover, inserting a special needle head with the length of about 12mm connected with the injector into the sampling device and piercing the bottom end of the sampling device, extracting a proper amount of lower-layer extract, directly measuring the content of chloride ions by a related analysis method, and finally calculating the salt content of the oil product expressed by mgNaCl/L according to a corresponding formula;
wherein: the sampling device is specifically composed of a funnel 1 with a turned edge 3 at the outer edge of the top end and a sampling channel 2 communicated with the bottom of the funnel, wherein the inner diameter of the turned edge 3 is smaller than the inner diameter of the top end of a centrifugal tube, the outer diameter of the turned edge 3 is larger than the inner diameter of the centrifugal tube and is not larger than the outer diameter of the centrifugal tube, the end of the sampling channel 2 is sealed by a film 4, and the film 4 is not contacted with the inner wall of the centrifugal tube; referring to fig. 1, in which the membrane 4 is also eliminated and the bottom end of the sampling channel 2 is closed, thus forming an integrated sampling device, which can be used by a needle directly penetrating the bottom thereof, in this embodiment the membrane 4 is provided;
referring to fig. 1, the method specifically includes the steps of firstly placing an oil product and a corresponding extraction liquid in a centrifugal tube, then placing a sampling device in the centrifugal tube, then covering a tube cover tightly, then placing a plurality of configured centrifugal tubes in equipment for shaking, and sampling to measure the salt content after the shaking is finished.
The technical scheme of the invention is further explained in detail by the following specific examples:
example 1
Weighing 5.94g of crude oil A, putting the crude oil A into a 50mL conical-bottom centrifuge tube with a cover, weighing the crude oil A to 0.01g, adding 9mL of dimethylbenzene, and uniformly mixing; adding 12mL of extract (water and ethanol with the volume ratio of 3:1 and containing 50mmol/L chlorine-free demulsifier and 100mmol/L citric acid), and then dropping 12 drops of hydrogen peroxide; inserting a sampling channel 2 into the centrifugal tube, erecting a funnel 1 and the sampling channel 2 integrally in the centrifugal tube through a flanging 3, and then screwing a tube cover for sealing; placing the centrifuge tube in 60-70 deg.C water bath for about 1min, taking out, uniformly and symmetrically placing in a sleeve of a sample disk of a constant temperature shaking and centrifuging integrated machine, and compacting; temperature setting: 70 ℃; shaking parameters: the shaking amplitude is 23mm, the shaking frequency is 1000Hz, and the duration is 5 min; centrifugal parameters: setting the rotating speed at 4000rpm for 5 min; layering the oil solution and the extract solution, screwing off a tube cover, inserting a special 12 mm-long needle connected with an injector into the sampling channel 2 along the funnel 1 and piercing the film 4, and extracting a proper amount of lower extract; injecting into an ion chromatography sample injection valve, measuring the content of chloride ions after starting, and finally calculating the salt content of the oil product expressed by mgNaCl/L according to a corresponding formula to be 32.4.
Example 2
Weighing 7.95g of dehydrated crude oil A, putting the weighed crude oil A into a 50mL conical-bottom centrifuge tube with a cover, weighing the crude oil A to 0.01g, adding 12mL of dimethylbenzene, and uniformly mixing; then 16mL of extract (water and ethanol with the volume ratio of 3:1 and containing 200mmol/L of chlorine-free demulsifier and 100mmol/L of acetic acid) is added, and then 16 drops of hydrogen peroxide are dropped; inserting a sampling channel 2 into the centrifugal tube, erecting a funnel 1 and the sampling channel 2 integrally in the centrifugal tube through a flanging 3, and then screwing a tube cover for sealing; placing the centrifuge tube in 60-70 deg.C water bath for about 1min, taking out, uniformly and symmetrically placing in a sleeve of a sample disk of a constant temperature shaking and centrifuging integrated machine, and compacting; temperature setting: 70 ℃; shaking parameters: the shaking amplitude is 24mm, the shaking frequency is 1100Hz, and the time duration is 7 min; centrifugal parameters: setting the rotating speed at 4000rpm for 5 min; layering the oil solution and the extract solution, inserting a special needle with the length of 12mm connected with an injector into the sampling channel 2 along the funnel 1, piercing the film 4, and extracting a proper amount of lower extract; injecting 20 μ L into electrolytic cell, setting parameters and conditions according to SY/T0536 method, starting Coulomb salt content meter application program, measuring chloride ion content, and calculating oil salt content expressed by mgNaCl/L according to corresponding formula to obtain 3.1.
Example 3
Weighing 7.96g of the crude oil B after removal, putting the crude oil B into a 50mL centrifuge tube with a conical bottom and a cover, weighing the crude oil B to 0.01g, adding 12mL dimethylbenzene, and uniformly mixing; then 16mL of extract (water and ethanol with the volume ratio of 3:1 and containing 200mmol/L of chlorine-free demulsifier and 60mmol/L of acetic acid) is added, and then 16 drops of hydrogen peroxide are dropped; inserting a sampling channel 2 into the centrifugal tube, erecting a funnel 1 and the sampling channel 2 integrally in the centrifugal tube through a flanging 3, and then screwing a tube cover for sealing; placing the centrifuge tube in 60-70 deg.C water bath for about 1min, taking out, uniformly and symmetrically placing in a sleeve of a sample disk of a constant temperature shaking and centrifuging integrated machine, and compacting; temperature setting: 60 ℃; shaking parameters: the shaking amplitude is 25mm, the shaking frequency is 1050Hz, and the duration is 10 min; centrifugal parameters: setting the rotating speed at 4500rpm for 5 min; layering the oil solution and the extract solution, inserting a special needle with the length of 12mm connected with an injector into the sampling channel 2 along the funnel 1, piercing the film 4, and extracting a proper amount of lower extract; taking 5mL of extract liquid, adding the extract liquid into a titration cup, setting parameters and conditions according to the requirements of a GB/T6532 method, starting a potentiometric titrator, measuring the chloride ion content, and finally calculating the oil product salt content expressed by mgNaCl/L according to a corresponding formula to be 23.2.
Example 4
Weighing 5.11g of the crude oil B after removal, putting the crude oil B into a 50mL centrifuge tube with a conical bottom and a cover, weighing the crude oil B to 0.01g, adding 8mL dimethylbenzene and uniformly mixing; then 10mL of water-ethanol-acid extract (the volume ratio is 3:1, 170mmol/L of chlorine-free demulsifier and 50mmol/L of acetic acid are contained) is added, and then 10 drops of hydrogen peroxide are dropped; inserting a sampling channel 2 into the centrifugal tube, erecting a funnel 1 and the sampling channel 2 integrally in the centrifugal tube through a flanging 3, and then screwing a tube cover for sealing; placing the centrifuge tube in 60-70 deg.C water bath for about 1min, taking out, uniformly and symmetrically placing in a sleeve of a sample disk of a constant temperature shaking and centrifuging integrated machine, and compacting; temperature setting: 65 ℃; shaking parameters: the shaking amplitude is 25mm, the shaking frequency is 1050Hz, and the duration is 7 min; centrifugal parameters: setting the rotating speed to 4200rpm, and setting the time duration to 6 min; layering the oil solution and the extract solution, inserting a special needle with the length of 12mm connected with an injector into the sampling channel 2 along the funnel 1, piercing the film 4, and extracting a proper amount of lower extract; injecting 20 mu L of the oil product into an electrolytic cell, setting parameters and conditions according to the requirements of the SY/T0536 method, starting an application program of a coulomb salt content meter, and finally calculating the salt content of the oil product expressed by mgNaCl/L according to a corresponding formula to be 2.6.
Example 5
Weighing 6.12g of the crude oil B after removal, putting the crude oil B into a 50mL centrifuge tube with a conical bottom and a cover, weighing the crude oil B to 0.01g, adding 9mL dimethylbenzene, and uniformly mixing; then adding 12mL of extract (water and ethanol with the volume ratio of 3:1 and containing 120mmol/L chlorine-free demulsifier and 80mmol/L citric acid), and then dropping 10 drops of hydrogen peroxide; inserting a sampling channel 2 into the centrifugal tube, erecting a funnel 1 and the sampling channel 2 integrally in the centrifugal tube through a flanging 3, and then screwing a tube cover for sealing; placing the centrifuge tube in 60-70 deg.C water bath for about 1min, taking out, uniformly and symmetrically placing in a sleeve of a sample disk of a constant temperature shaking and centrifuging integrated machine, and compacting; temperature setting: 70 ℃; shaking parameters: the shaking amplitude is 23mm, the shaking frequency is 1000Hz, and the duration is 10 min; centrifugal parameters: setting the rotating speed at 4300rpm for 5 min; layering the oil solution and the extract solution, inserting a special needle with the length of 12mm connected with an injector into the sampling channel 2 along the funnel 1, piercing the film 4, and extracting a proper amount of lower extract; and (3) taking the injection ion chromatography sample injection valve, starting the injection ion chromatography sample injection valve, measuring the content of chloride ions, and finally calculating the salt content of the oil product expressed by mgNaCl/L according to a corresponding formula to be 2.7.
Example 6
Weighing 4.10g of crude oil C, putting into a 50mL centrifuge tube with a conical bottom and a cover, weighing to 0.01g, adding 6mL of dimethylbenzene, and uniformly mixing; then 8mL of extract (water and ethanol with the volume ratio of 3:1 and containing 190mmol/L of chlorine-free demulsifier and 100mmol/L of citric acid) is added, and then 10 drops of hydrogen peroxide are dropped; inserting a sampling channel 2 into the centrifugal tube, erecting a funnel 1 and the sampling channel 2 integrally in the centrifugal tube through a flanging 3, and then screwing a tube cover for sealing; placing the centrifuge tube in 60-70 deg.C water bath for about 1min, taking out, uniformly and symmetrically placing in a constant temperature shaking and centrifuging integrated machine sample tray, and compacting; shaking parameters: amplitude-max, duration 10min, centrifugation parameters: the rotating speed is 4400rpm, and the time length is 10 min; layering the oil solution and the extract solution, inserting a special needle with the length of 12mm connected with an injector into the sampling channel 2 along the funnel 1, piercing the film 4, and extracting a proper amount of lower extract; taking 5mL of extract liquid, adding the extract liquid into a titration cup, setting parameters and conditions according to the requirements of a GB/T6532 method, starting a potentiometric titrator, measuring the chloride ion content, and finally calculating the oil product salt content expressed by mgNaCl/L according to a corresponding formula to be 28.7.
In the test platform, the equipment structure of the constant-temperature shaking and centrifuging integrated machine is the same as that of a shaking and centrifuging coupling device shown in patent text CN105115809B, and a constant-temperature structure is additionally arranged in the equipment, so that the equipment can shake and centrifuge an oil product in a constant-temperature environment; LC-6Y microcoulomb (electric method) salt content instrument, manufactured by Jiang Wei Analyzer factory in Tazhou; model 930 intelligent integrated ion chromatograph, Metrosep A Supp 5-250/4.0 anion chromatographic column, 905 automatic potentiometric titrator, 848 automatic sample converter, and composite silver electrode (6.0450.100) with internal filling liquid of KNO3(sat.) were all manufactured by Switzerland Wantong (Metrohm).
Finally, it should also be noted that the above-mentioned list is only a specific embodiment of the invention. It is obvious that the invention is not limited to the above embodiments. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.
Claims (4)
1. An oil product salt content integrated batch pretreatment and sampling method is characterized by comprising the following steps:
step 1, quantitatively putting an oil product to be treated into a 50mL centrifuge tube with a conical bottom and a cover, adding a dimethyl benzene diluent, uniformly mixing, adding an extract liquid, dropping hydrogen peroxide, putting a sampling device into the centrifuge tube, screwing a tube cover to seal the centrifuge tube, and fixing the sampling device to obtain the oil product centrifuge tube to be treated;
wherein: the sampling device is composed of a funnel with a flanging at the top end outer edge and a sampling channel communicated with the bottom of the funnel, wherein the inner diameter of the flanging is smaller than the inner diameter of the top end of the centrifugal tube, the outer diameter of the flanging is larger than the inner diameter of the centrifugal tube and not larger than the outer diameter of the centrifugal tube, the end of the sampling channel is sealed by a thin film, and the sealing film is not contacted with the inner wall of the centrifugal tube when the sampling device is arranged in;
step 2, repeating the step 1 to prepare a plurality of oil centrifugal tubes to be treated, uniformly and symmetrically placing the plurality of oil centrifugal tubes to be treated in a sample disc sleeve of the constant-temperature shaking and centrifuging all-in-one machine for fixation, and performing shaking extraction and centrifugal layering; after the completion, the tube cap is screwed off, a 12mm long needle connected with an injector is inserted into the sampling channel and pierces the sealing membrane, the solution under the oil layer is extracted for detection, potentiometric titration or microcoulometric titration or ion chromatography is carried out to measure the chloride ion content, and finally the salt content of the oil product expressed by mgNaCl/L is calculated.
2. The integrated batch pretreatment and sampling method for the salt content of the oil product according to claim 1, wherein the centrifuge tube and the tube cover are made of chlorine-free high-density polypropylene, the sampling device is specifically made of chlorine-free low-density polyethylene, the length ratio of the long and thin closed cavity in the sampling device to the upper part of the funnel shape is 4: 1-5: 1, and the distance between the bottom of the sealing film and the bottom of the core tube is less than or equal to 0.5cm when the sampling device is fixed in the centrifuge tube.
3. The integrated batch pretreatment and sampling method for the salt content of the oil product according to claim 2, characterized in that the extract is water and ethanol with a volume ratio of 3:1, contains 100-200 mmol/L of a chlorine-free demulsifier and 50-100 mmol/L of citric acid or acetic acid, the amount of the extract is 10-16 mL, the amount of hydrogen peroxide is 8-16 drops, the amount of xylene is 7.5-12 mL, and the mass of the oil product is 5-8 g.
4. The integrated batch pretreatment and sampling method for the salt content of the oil product according to claim 1, characterized in that the constant temperature shaking and centrifuging integrated machine is formed by adding a temperature rise control and control device to a QuEChERS automatic sample preparation system, shaking, mixing and extracting and finally coupling centrifuging and layering, and the specific process comprises a constant temperature range of 60-80 ℃, a shaking time of 5-10 min, a shaking amplitude of 23-25 mm, a shaking frequency of 1000-1100 Hz, a centrifugal rotation speed of 4000-4500 rpm and a centrifugal time of 5-10 min.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115475412A (en) * | 2022-10-20 | 2022-12-16 | 深圳瑞亚力集团有限公司 | Purification method for oil generated by liquid drops |
| CN115475412B (en) * | 2022-10-20 | 2024-02-02 | 深圳瑞亚力集团有限公司 | Purification method for liquid drop generated oil |
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