CN215263299U - Long-chain fatty acid salt chromatographic analysis pretreatment system - Google Patents

Abstract

A long-chain fatty acid salt chromatographic analysis pretreatment system belongs to the technical field of long-chain fatty acid salt chromatographic analysis pretreatment. The raw materials for preparing the long-chain fatty acid salt are natural products, the composition is relatively complex, and the long-chain fatty acid salt has special properties after being salified, so that a lot of difficulties are brought to analysis and detection. Because of their salt nature, they are far less volatile than neutral organic compounds and cannot be directly analyzed by gas chromatography; in addition, the mixed organic acid salt has high hydrophilicity, and has no separation effect in conventional liquid chromatography. The utility model utilizes a primary reaction tank, a membrane separator and a secondary reaction tank; the discharge port of the first-stage reaction tank is connected with the input port of the membrane separator, and the output port of the membrane separator is connected with the input port of the second-stage reaction tank. Long-chain fatty acid salt is converted into fatty acid, and the fatty acid is converted into fatty acid methyl ester after being washed by water, so that the separation by gas chromatography is easy. The fatty acid group is separated and converted step by step in a chemical-physical-chemical conversion mode, and purification and conversion are integrated.

Description

Long-chain fatty acid salt chromatographic analysis pretreatment system

Technical Field

A long-chain fatty acid salt chromatographic analysis pretreatment system belongs to the technical field of long-chain fatty acid salt chromatographic analysis pretreatment.

Background

The raw materials for preparing the long-chain fatty acid salt are all natural products, the composition is relatively complex, the long-chain fatty acid salt is generally composed of dozens of natural products, the source fluctuation of the raw materials is relatively high, and the long-chain fatty acid salt has special properties after being salified, so that a lot of difficulties are brought to analysis and detection. Because of their salt nature, they are far less volatile than neutral organic compounds and cannot be directly analyzed by gas chromatography; in addition, the mixed organic acid salt has high hydrophilicity, and has no separation effect in conventional liquid chromatography. How to convert the organic acid salt into a non-ionic compound that can be chromatographed is critical and must be pretreated.

For small-molecular organic acid salts, acidification treatment is firstly carried out, mixed sodium fatty acid is converted into free acid, and then chromatographic determination is carried out, but organic acids with relatively large molecular weight, particularly long-carbon-chain fatty acid (more than C12), generally have very high boiling point and are not suitable for direct chromatographic analysis. The fatty acid has strong polarity, belongs to a thermosensitive substance, has low volatility and thermal stability, is unstable at high temperature, is easy to generate side reactions such as polymerization, deacidification and cracking, is easy to cause loss in analysis, and influences the accuracy of an analysis result. In addition, high boiling point components are easy to be distinguished, if the analysis is directly carried out, the column temperature is very high, a high-temperature fixed phase is difficult to select, chromatographic peaks are trailing, retention time is not repeated, false peaks sometimes appear, and the like, so that inaccurate quantification is caused. Thus, chromatographic analysis of long carbon chain fatty acids typically requires pretreatment to convert the fatty acid to a less polar fatty acid ester to increase vapor pressure and thermal stability.

Disclosure of Invention

The utility model discloses the technical problem that will solve is: overcomes the defects of the prior art, and provides a long-chain fatty acid salt chromatographic analysis pretreatment system for chromatographic analysis, which can remove interferents and convert mixed long-chain fatty acid salts into chemical forms suitable for analytical determination.

The utility model provides a technical scheme that its technical problem adopted is: a long-chain fatty acid salt chromatographic analysis pretreatment system is characterized in that: comprises a first-stage reaction tank, a heat exchanger, a membrane separator and a second-stage reaction tank; the discharge port of the first-stage reaction tank is connected with the input port of the membrane separator, and the output port of the membrane separator is connected with the input port of the second-stage reaction tank; the heat exchanger is arranged on a pipeline between the first-stage reaction tank and the membrane separator, a tube side inlet of the heat exchanger is connected with a discharge port of the first-stage reaction tank, and a tube side outlet of the heat exchanger is connected with an input port of the membrane separator.

The long-chain fatty acid salt and hydrochloric acid are fully reacted in a first-stage reaction tank to convert the long-chain fatty acid salt into fatty acid and chloride, the fatty acid and the chloride directly enter a membrane separator after the reaction is finished, the temperature is adjusted by a heat exchanger under the condition of water, and then the fatty acid and the chloride are separated by washing with water by the membrane separator; and (3) outputting the separated fatty acid from an output port of the membrane separator into a secondary reaction tank, adding methanol into the secondary reaction tank, and performing esterification reaction under the catalysis and heating conditions to generate fatty acid methyl ester. The fatty acid methyl ester has low boiling point and is easy to volatilize, and the separation effect is good; the heat exchanger can carry out one step of cooling to the material before getting into the membrane separator, avoids coming from the high temperature material of one-level retort to make the temperature in the membrane separator produce fluctuation by a wide margin and influences the separation effect of membrane separator, also can avoid being used for the water of washing in the membrane separator simultaneously and the material difference in temperature great, and the mixing effect is poor, and washing is insufficient.

The primary reaction tank converts long-chain fatty acid salt into fatty acid and converts impurity ions into salt which can be separated by washing in the membrane separator, the fatty acid which is easy to separate is added with a step of reaction and is converted into a substance which is easy to volatilize so as to meet the requirement of gas chromatography, chemical conversion and physical washing are combined, the separation is performed step by step in a chemical-physical-chemical conversion form, the fatty acid group is converted, purification and conversion are integrated, the whole system is simple in structure, the separation effect of each step on the substance is stable, operation is stable, the long-chain fatty acid salt can be pretreated continuously, and each step can be controlled to start and stop independently, the use is convenient, and the heat exchanger is added to further stabilize the washing and membrane separation effects.

Preferably, the shell side outlet of the heat exchanger is communicated with the input port of the membrane separator. The cooling water used for cooling the materials in the heat exchanger is directly utilized to wash the materials in the membrane separator, and because the cooling water and the materials have already carried out heat exchange once, the temperature is closer, the temperature change in the membrane separator is smaller, the mixing is more uniform, and meanwhile, the water can be saved.

Preferably, the primary reaction tank is provided with a hydrochloric acid input pipe, a sample input pipe and an input sampling valve; the input sampling valve is arranged on the sample input pipe, and the hydrochloric acid input pipe and the sample input pipe are respectively communicated with the primary reaction tank. Make one-level retort can be in normal confined state, further strengthen the reaction environment of stabilizing inside, also can keep a jar confined state including the sample before the reaction, can take a sample at any time and monitor and get into jar interior sample state when continuous preliminary treatment.

Preferably, the input sampling valve comprises a valve main body, a sampling tube, a valve rod and a spring, the sampling tube is communicated with the outside and the valve main body, the valve rod is arranged in the valve main body and is coaxial with the sampling tube, the lower end of the valve rod is provided with a sealing part, and the diameter of one end, close to the valve rod, of the sealing part is larger than the minimum diameter of the sampling tube; the other end of the valve rod penetrates through the outer wall of the valve main body; the valve rod is sleeved with a spring; the valve body is communicated with the sample input pipe.

Considering that the general sample input pipe is vertically arranged at the upper side of the first-stage reaction tank, the valve main body is generally a pipe type and is also vertically arranged on the sample input pipe as a section of the sample input pipe, and the sampling pipe and the valve rod are generally communicated with the valve main body in a direction vertical to the sample input pipe.

One end of the spring props against the inner wall of the valve main body, the other end of the spring props against one end of the sealing part close to the valve rod, so that the sampling tube is plugged by the sealing part, and materials from the sample input tube enter the first-stage reaction tank after passing through the valve main body; when the needs sample, through the valve rod part that exposes outside the valve main part, pull up the valve rod to the external direction, the sampling tube and valve main part intercommunication, the material can flow in the sampling tube, accomplishes the sample.

Preferably, the sealing portion is in a truncated cone shape with a diameter decreasing in a direction away from the valve stem. The small head part of the circular truncated cone can partially enter the sampling tube, and the large head part is plugged tightly, so that the sealing effect on the sampling tube is enhanced.

Preferably, the device further comprises a liquid baffle; the valve rod is equipped with semicircular fender liquid board in the one end both sides that are close to sealing, and the plane perpendicular to sample input tube in fender liquid board place to the one end that the sampling tube is close to valve main part is equipped with fender liquid board groove.

The fender liquid board is in the fender liquid board inslot on the sampling tube when not needing the sample, does not hinder the sample input, when needs sample, keeps off the liquid board and can together be mentioned when mentioning the valve rod, blocks the material from last section sample input tube directly flowing into next section sample input tube, and better drainage material gets into the sampling tube, improves sampling efficiency.

Preferably, the device further comprises an output sampling valve; the output sampling valve is arranged on a pipeline between the discharge port of the primary reaction tank and the input port of the membrane separator; the structure of the output sampling valve is the same as that of the input sampling valve. The material of output sample valve when to the blowing can be taken a sample, and on the one hand detects the reaction effect, and on the other hand obtains the testing result contrast that sample and input sample valve obtained the sample through output sample valve and can reflect and monitor whether the reaction environment in the one-level retort appears changing.

Preferably, the secondary reaction tank is provided with a jacket, a methanol input pipe and a concentrated sulfuric acid input pipe, the jacket is sleeved outside the secondary reaction tank, and the methanol input pipe and the concentrated sulfuric acid input pipe are communicated with the secondary reaction tank. The input pipe for each reaction raw material is arranged, so that the secondary reaction tank can continuously react under the condition of not opening the tank, the reaction environment in the tank is favorably maintained, the reaction result is more stable, and more stable continuous pretreatment is realized.

Compared with the prior art, the utility model discloses the beneficial effect who has is: the method can realize continuous reaction of long-chain fatty acid salt with hydrochloric acid to generate fatty acid and hydrochloride, wash the fatty acid and remove the hydrochloride, then carry out esterification reaction on the fatty acid after acidification and extraction by adopting a methanol-sulfuric acid esterification derivatization method, has high conversion rate of the fatty acid esterification reaction, reacts the fatty acid with high boiling point and difficult volatilization and vaporization with methanol under the conditions of a catalyst and heating to generate fatty acid methyl ester, and changes the fatty acid methyl ester into a low boiling point and volatile substance, thereby reducing the vaporization temperature, improving the separation effect and stability, eliminating the influence of interferents, facilitating the separation of gas chromatography, separating and converting fatty acid groups step by step in a chemical-physical-chemical conversion form, integrating purification and conversion, and the whole system has simple structure, stable separation effect of each step on the substances, stable operation and continuous pretreatment of the long-chain fatty acid salt, and each step can be controlled independently to start and stop, and the use is convenient. The sampling valve is convenient to operate, and can monitor the reaction condition and the reaction environment in the reaction tank timely and accurately.

Drawings

FIG. 1 is a schematic diagram of a pretreatment system for chromatography of long chain fatty acid salts according to example 1.

FIG. 2 is a schematic view of a sampling valve according to example 1.

FIG. 3 is a schematic view of a sampling valve according to example 2.

FIG. 4 is a side view showing the structure of a sampling valve according to example 2.

Wherein, 1 hydrochloric acid input tube, 2 measuring pumps, 3 sample valves of input, 4 first-order retort, 5 output stop valves, 6 output sample valves, 7 sample input tubes, 8 heat exchangers, 9 membrane separators, 10 second-order retort, 11 jackets, 12 methanol input tubes, 13 concentrated sulfuric acid input tubes, 14 valve main bodies, 15 sample tubes, 16 valve rods, 1601 sealing parts, 1602 baffle plate, 1603 spring groove, 17 springs, 18 moisturizing pipe.

Detailed Description

The present invention will be further explained with reference to fig. 1 to 4, and embodiment 2 is the best embodiment of the present invention.

Example 1

Referring to the attached figures 1-2: a long-chain fatty acid salt chromatographic analysis pretreatment system comprises an input sampling valve 3, a primary reaction tank 4, an output sampling valve 6, a heat exchanger 8, a membrane separator 9 and a secondary reaction tank 10; the discharge port of the first-stage reaction tank 4 is sequentially provided with an output stop valve 5 and an output sampling valve 6 and is connected with the tube side inlet of a heat exchanger 8, and the tube side outlet of the heat exchanger 8 is connected with the input port of a membrane separator 9; a shell pass inlet of the heat exchanger 8 is connected with a cooling water pipe, and a shell pass outlet is connected with a water replenishing pipe 18 and then communicated with an input port of the membrane separator 9; the output port of the membrane separator 9 is connected with the input port of the secondary reaction tank 10.

Wherein, the primary reaction tank 4 is provided with a hydrochloric acid input pipe 1, a sample input pipe 7 and an input sampling valve 3; a metering pump 2 is arranged on the hydrochloric acid input pipe 1 to meter the adding amount of the hydrochloric acid; the input sampling valve 3 is arranged on the sample input pipe 7, the input sampling valve 3 comprises a valve main body 14, a sampling pipe 15, a valve rod 16 and a spring 17, the sampling pipe 15 is communicated with the outside and the valve main body 14, the valve rod 16 is arranged in the valve main body 14 and is coaxially arranged with the sampling pipe 15, a sealing part 1601 is arranged at the lower end of the valve rod 16, the sealing part 1601 is in a circular truncated cone shape with the diameter reduced along the direction far away from the valve rod 16, the diameter of one end close to the valve rod 16 is larger than the minimum diameter of the sampling pipe 15, and the end with the smaller diameter of the sealing part 1601 can enter the sampling pipe 15; the other end of the valve stem 16 passes through the outer wall of the valve body 14, and is exposed to the outside of the valve body 14; a spring 17 is sleeved on the valve rod 16, one end of the spring 17 is propped against the inner wall of the valve main body 14, and the other end of the spring 17 is propped against one end of the sealing part 1601 close to the valve rod 16, so that the sealing part 1601 plugs the sampling tube 15; the valve body 14 is communicated with the sample input pipe 7; the sample input pipe 7 is vertically arranged on the upper side of the first-stage reaction tank 4, the valve main body 14 is a pipe type and is also vertically arranged on the sample input pipe 7 as a section of the sample input pipe 7, the sampling pipe 15 and the valve rod 16 are communicated with the valve main body 14 in a direction vertical to the sample input pipe 7, and the structure of the output sampling valve 6 is the same as that of the input sampling valve 3.

The secondary reaction tank 10 is provided with a jacket 11, a methanol input pipe 12 and a concentrated sulfuric acid input pipe 13, the jacket 11 is sleeved outside the secondary reaction tank 10, and the methanol input pipe 12 and the concentrated sulfuric acid input pipe 13 are communicated with the secondary reaction tank 10.

Hydrochloric acid is added into a first-stage reaction tank 2 after being metered by a metering pump 2 from a hydrochloric acid input pipe 1, a long-chain fatty acid salt sample enters the first-stage reaction tank 2 from a sample input pipe 7 after passing through an input sampling valve 3, a certain input sample is obtained from a sampling pipe 15 by lifting a valve rod 16 on the input sampling valve 3 when the sample is input, the long-chain fatty acid salt and the hydrochloric acid are converted into fatty acid and sodium chloride in the first-stage reaction tank 4 in an acidification mode, the fatty acid and the sodium chloride sequentially pass through an output stop valve 5 and an output sampling valve 6 during discharging, and the output sample can be obtained from the output sampling valve 6 at any time. The material after the first-stage reaction passes through the tube pass of the heat exchanger 8 and is cooled by cooling water of the shell pass; cooling water in the inner shell pass part of the heat exchanger 8 directly serves as washing water to cool the tube pass materials, then the washing water and the tube pass materials enter the membrane separator 9 together, fatty acid is separated from sodium chloride through a washing method, and only when the washing efficiency requirement is high, a water replenishing pipe 18 is adopted to replenish water to the membrane separator 9; the separated fatty acid enters a secondary reaction tank 10, the secondary reaction tank 10 heats the tank through a jacket 11, and methanol and concentrated sulfuric acid are added through a methanol input pipe 12 and a concentrated sulfuric acid input pipe 13, so that the fatty acid and the methanol are subjected to esterification reaction, the high-boiling-point non-volatile gasified fatty acid and the methanol are converted into fatty acid methyl ester under the catalytic heating condition, the low boiling point is volatile, the gas chromatography separation is convenient, and the separation effect is stable.

Example 2

Referring to figures 3 to 4: a long-chain fatty acid salt chromatographic analysis pretreatment system, the other conditions are the same as the embodiment 1, the difference is only that the valve rod 16 in the input sampling valve 3 and the output sampling valve 6 is provided with a semicircular liquid baffle plate 1602 at two sides of one end close to the sealing part 1601, the plane where the two liquid baffle plates 1602 are located is vertical to the sample input pipe 7, and the diameter of one end of the sampling pipe 15 close to the valve main body 14 is larger than the maximum diameter of the sealing part 1601, namely, the inside of the sampling pipe presents a step shape with one thick end and one thin end, which can make the sealing part 1601 completely enter one section of the sampling pipe 15; a liquid baffle groove corresponding to the shape of the liquid baffle 1602 is also arranged at one end of the sampling tube 15 close to the valve main body 14; meanwhile, the liquid blocking plate 1602 is provided with a spring groove 1603 at one end far away from the sealing part 1601, so that one end of the spring 17 which is supposed to be pressed against the sealing part 1601 is pressed against the spring groove 1603.

The liquid baffle 1602 can block the sample and directly flow into next section sample input tube 7 when lifting up valve rod 16 sample, makes more samples be the drainage and gets into sampling tube 15, improves sampling efficiency. The sealing portion 1601 is completely plugged into a section of the sampling tube 15, so that the flow blockage of the material can be avoided when the sampling is not needed, and meanwhile, the sealing effect on the sampling tube 15 is enhanced.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical substance of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (8)

1. A long-chain fatty acid salt chromatographic analysis pretreatment system is characterized in that: comprises a first-stage reaction tank (4), a heat exchanger (8), a membrane separator (9) and a second-stage reaction tank (10); the discharge port of the first-stage reaction tank (4) is connected with the tube pass inlet of the heat exchanger (8), the tube pass outlet of the heat exchanger (8) is connected with the input port of the membrane separator (9), and the output port of the membrane separator (9) is connected with the input port of the second-stage reaction tank (10).

2. The long chain fatty acid salt chromatography pretreatment system of claim 1, characterized in that: and a shell side outlet of the heat exchanger (8) is communicated with an input port of the membrane separator (9).

3. The long chain fatty acid salt chromatography pretreatment system of claim 1, characterized in that: the primary reaction tank (4) is provided with a hydrochloric acid input pipe (1), a sample input pipe (7) and an input sampling valve (3); the input sampling valve (3) is arranged on the sample input pipe (7), and the hydrochloric acid input pipe (1) and the sample input pipe (7) are respectively communicated with the primary reaction tank (4).

4. The long chain fatty acid salt chromatography pretreatment system of claim 3, characterized in that: the input sampling valve (3) comprises a valve main body (14), a sampling pipe (15), a valve rod (16) and a spring (17), wherein the sampling pipe (15) is communicated with the outside and the valve main body (14), the valve rod (16) is arranged in the valve main body (14) and is coaxially arranged with the sampling pipe (15), a sealing part (1601) is arranged at the lower end of the valve rod (16), and the diameter of one end, close to the valve rod (16), of the sealing part (1601) is larger than the minimum diameter of the sampling pipe (15); the other end of the valve rod (16) penetrates through the outer wall of the valve main body (14); a spring (17) is sleeved on the valve rod (16); the valve main body (14) is communicated with the sample input pipe (7).

5. The long chain fatty acid salt chromatography pretreatment system of claim 4, characterized in that: the sealing part (1601) is in a truncated cone shape with a diameter decreasing along a direction away from the valve rod (16).

6. The long chain fatty acid salt chromatography pretreatment system of claim 3, characterized in that: the device also comprises a liquid baffle (1602); a semicircular liquid baffle plate (1602) is arranged on each of two sides of one end, close to the sealing part (1601), of the valve rod (16); the plane of the two liquid baffle plates (1602) is perpendicular to the sample input pipe (7), and one end of the sampling pipe (15) close to the valve main body (14) is provided with a liquid baffle plate groove corresponding to the liquid baffle plates (1602).

7. The long chain fatty acid salt chromatography pretreatment system of claim 1, characterized in that: also comprises an output sampling valve (6); the output sampling valve (6) is arranged on a pipeline between the discharge port of the primary reaction tank (4) and the input port of the membrane separator (9); the structure of the output sampling valve (6) is the same as that of the input sampling valve (3).

8. The long chain fatty acid salt chromatography pretreatment system of claim 1, characterized in that: the device is characterized in that a jacket (11), a methanol input pipe (12) and a concentrated sulfuric acid input pipe (13) are arranged on the secondary reaction tank (10), the jacket (11) is sleeved on the outer side of the secondary reaction tank (10), and the methanol input pipe (12) and the concentrated sulfuric acid input pipe (13) are communicated with the secondary reaction tank (10).

Images