Pretreatment system and method for detecting the content of isooctyl acrylate in stannous octoate

Abstract

The invention discloses a pretreatment system and method for detecting the content of isooctyl acrylate in stannous octoate, and belongs to the technical field of analysis and detection. The system includes an extraction reaction container, a microporous fine mist agitator and a heat conduction device; the extraction reaction container includes a tank body with a reaction chamber, and a plurality of material inlets are arranged on the top of the tank body; the microporous fine mist agitator is arranged in the reaction chamber, and includes a stirring head and a hollow stirring rod, one end of the hollow stirring rod is connected to part of the material inlet, and the other end is connected to the hollow stirring head with micropores on the surface; the heat conduction device is arranged on the periphery of the tank body; an opening is arranged at the bottom of the heat conduction device, and a material outflow channel is formed between the bottom of the tank body and the opening. The system can effectively remove isooctyl acid in the sample to be tested, avoid the interference of isooctyl acid on the peak of isooctyl acrylate, and improve the accuracy of the detection result. The corresponding detection method is simple, easy to operate, has strong specificity, high accuracy, good reproducibility, and accurate and reliable detection results.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and detection, and in particular to a pretreatment system and method for detecting the content of isooctyl acrylate in stannous octoate. Background Art

[0002] Stannous octoate is the most widely used tin catalyst in the polyurethane industry. It can accelerate the cross-linking reaction between polyether polyols and TDI. When used in combination with amine catalysts, it can balance the foaming reaction and the cross-linking reaction, thereby obtaining a foam plastic product with uniform pores and good air permeability. Therefore, stannous octoate plays an extremely important role in the manufacture of polyurethane foams, especially soft foams.

[0003] The main raw material for the synthesis of stannous octoate is 2-ethylhexyl acrylate (2-EHA), which contains trace amounts of 2-ethylhexyl acrylate (2-EHA). 2-ethylhexyl acrylate (2-EHA) is of low toxicity and irritating to the skin and eyes. Long-term contact or absorption through the skin can cause poisoning, so 2-ethylhexyl acrylate (2-EHA) is becoming a contaminant that cannot be ignored in foam products.

[0004] Currently, the main methods for detecting acrylates are gas chromatography, thermal desorption gas chromatography, gas chromatography-mass spectrometry and headspace gas chromatography.

[0005] The above-mentioned gas chromatography is often used to determine the purity of acrylates; thermal analysis gas chromatography is often used to detect acrylates in the air, and the method is to collect with activated carbon, analyze with carbon disulfide, and then conduct gas phase analysis; gas chromatography-mass spectrometry is often used to determine the residual amount of methoxyacrylate fungicides in food, and the method is to use organic solvent ultrasonic extraction, GPC system purification, and then conduct gas phase analysis.

[0006] However, the above method is not suitable for detecting the content of isooctyl acrylate in stannous octoate, and the detection result is not accurate.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] One of the purposes of the present invention is to provide a pretreatment system for detecting the content of isooctyl acrylate in stannous octoate, which can improve the accuracy of the result of detecting the content of isooctyl acrylate in stannous octoate.

[0009] The second object of the present invention is to provide a method for detecting the content of isooctyl acrylate in stannous octoate.

[0010] This application can be implemented as follows:

[0011] In a first aspect, the present application provides a pretreatment system for detecting the content of isooctyl acrylate in stannous octoate, comprising an extraction reaction device;

[0012] The extraction reaction equipment comprises an extraction reaction container, a microporous fine mist agitator and a heat conduction device;

[0013] The extraction reaction container comprises a tank body with a reaction chamber, and a water inlet, an n-butanol inlet, a reaction solvent inlet, a cleaning solvent inlet, a protective gas inlet and a stannous octoate sample inlet are arranged on the top of the tank body;

[0014] The microporous fine mist agitator is arranged in the reaction chamber, and the microporous fine mist agitator comprises a stirring head and a hollow stirring rod, one end of the hollow stirring rod is connected to the reaction solvent inlet, the cleaning solvent inlet and the protective gas inlet, and the other end of the hollow stirring rod is connected to the hollow stirring head, and micropores are opened on the surface of the hollow stirring head;

[0015] The heat conduction device is arranged on the outer periphery of the tank body and is used to conduct heat to the material in the reaction chamber; an opening is arranged at the bottom of the heat conduction device, a material outflow channel is formed between the bottom of the tank body and the opening, and a valve is arranged at the opening.

[0016] In an optional embodiment, the tank body includes a top surface and an annular surface, the periphery of the top surface is connected to the top periphery of the annular surface, the top surface is a horizontal surface, and the annular surface is an arcuate surface.

[0017] In an optional embodiment, the top of the annular surface has an angle of 5-20° with the vertical direction.

[0018] In an optional embodiment, in the microporous fine mist agitator, the projection of the hollow agitator head in the vertical direction is semicircular.

[0019] In an alternative embodiment, the diameter of the semicircle is 50-150 mm.

[0020] In an optional embodiment, the diameter of the microholes provided in the hollow stirring head is 1-3 mm.

[0021] In an optional embodiment, the pretreatment system further comprises a first container for storing water, a second container for storing n-butanol, a third container for storing a reactive solvent, a fourth container for storing a cleaning solvent, and a fifth container for storing a protective gas;

[0022] The outlet of the first container is connected to the water inlet through a pipeline, the outlet of the second container is connected to the n-butanol inlet through a pipeline, the outlet of the third container is connected to the reaction solvent inlet through a pipeline, the outlet of the fourth container is connected to the cleaning solvent inlet through a pipeline, and the outlet of the fifth container is connected to the protective gas inlet through a pipeline.

[0023] In an optional embodiment, the reactive solvent inlet, the cleaning solvent inlet and the protective gas inlet share the same inlet.

[0024] In an optional embodiment, the outlet of the fifth container is connected to the inlets of the first container to the fourth container respectively through pipelines; a valve is provided on each connecting pipeline, wherein the valve on the pipeline connecting the outlet of the fifth container and the inlet of the second container is a four-way valve, and the other port of the four-way valve is connected to the protective gas inlet through a pipeline.

[0025] In an optional embodiment, when the reaction solvent inlet, the cleaning solvent inlet and the protective gas inlet share the same inlet, the pipeline connecting the other port of the four-way valve and the protective gas inlet, the pipeline connecting the outlet of the third container and the reaction solvent inlet, and the pipeline connecting the outlet of the fourth container and the cleaning solvent inlet are first merged into a main pipeline and then connected to the same shared inlet, and a booster pump is provided on the main pipeline.

[0026] In an optional embodiment, a first condenser is also integrated on the top of the tank body, and the top of the first condenser is connected to the outlet of the second container.

[0027] In an optional embodiment, a microporous pressure relief valve is also provided on the top of the first condenser.

[0028] In an optional embodiment, the height of the first condenser is 10-15 cm.

[0029] In an optional embodiment, a heat conducting medium inlet and a heat conducting medium outlet are respectively provided at the upper part and the lower part of the heat conducting device.

[0030] In an optional embodiment, the pre-treatment system further includes a negative pressure extraction device;

[0031] The negative pressure extraction equipment includes a magnetic stirrer with weighing and heating functions, an extraction container, a stirrer, a second condenser, a first waste liquid collection container and a vacuum pump;

[0032] The extraction container is used to be placed on the platform of the magnetic stirrer, the stirrer is used to be placed in the extraction container, the extraction container has an extraction container inlet and a material outlet, the extraction container inlet is connected to the opening at the bottom of the heat conduction device, one end of the second condenser is connected to the material outlet, the other end of the second condenser is connected to the inlet of the first waste liquid collection container, and the first waste liquid collection container is also connected to the vacuum pump.

[0033] In an optional embodiment, the second condenser includes a vertical section and a downwardly inclined section, one end of the vertical section is connected to the material outlet, the other end of the vertical section is connected to one end of the inclined section, and the other end of the inclined section is connected to the inlet of the first waste liquid collection container.

[0034] In an alternative embodiment, the height of the vertical section is 10-15 cm.

[0035] In an optional embodiment, the pretreatment system also includes a second waste liquid collection container, the inlet of the second waste liquid collection container is connected to the opening at the bottom of the heat transfer device, and the outlet of the second waste liquid collection container is connected to the water inlet, the n-butanol inlet and the top of the first condenser.

[0036] In a second aspect, the present application provides a method for detecting the content of isooctyl acrylate in stannous octoate, comprising the following steps: using the pretreatment system of the aforementioned embodiment to pre-treat the stannous octoate sample to be treated.

[0037] In an optional embodiment, the pretreatment includes: adding a stannous octoate sample, water and n-butanol into a tank body, passing a reactive solvent into the tank body from the micropores of a microporous fine mist agitator, and circulating a heat-conducting medium in a heat-conducting device until no bubbles are generated in the material in the tank body; then standing until the oil phase and the water phase are clearly separated, collecting the lower water phase in a second waste liquid collection container, collecting the upper oil phase in an extraction container, and discharging the n-butanol through a second condenser into the first waste liquid collection container under the heating action of a magnetic stirrer, and recording the final weight increase of the extraction container.

[0038] In an optional embodiment, before recording the final weight increase of the extraction container, the method further includes first passing a cleaning solvent from the micropores of the microporous fine mist agitator into the tank body to rinse the reaction chamber; and then passing a protective gas from the micropores of the microporous fine mist agitator into the tank body to purge the residual liquid in the reaction chamber into the extraction container.

[0039] In an optional embodiment, in the tank, the volume ratio of water to n-butanol is 1:5-40.

[0040] In an optional embodiment, the reaction solvent includes an aqueous solution of sodium bicarbonate, and the cleaning solvent includes at least one of toluene, acetonitrile and acetone.

[0041] In an optional embodiment, the stirring speed of the microporous fine mist agitator is 60-200 r / min.

[0042] In an optional embodiment, the temperature of the heat-conducting medium in the heat-conducting device is 80-115° C.; more preferably, the heat-conducting medium is heat-conducting silicone oil.

[0043] In an optional embodiment, the standing time is 30-120 min.

[0044] In an optional embodiment, the method further comprises: mixing the stannous octoate obtained by pre-treatment with an inhibitor and an internal standard, and then detecting the content of isooctyl acrylate by headspace-gas chromatography.

[0045] In an alternative embodiment, the polymerization inhibitor includes methylhydroquinone and 2-tert-butylhydroquinone.

[0046] In an optional embodiment, the amount of methylhydroquinone used is 20-50 ppm, and the amount of 2-tert-butylhydroquinone used is 20-50 ppm.

[0047] In an optional embodiment, the detection conditions of the head space sampler include: a heating box temperature of 160-210°C, a quantitative loop temperature of 160-210°C, a transmission line temperature of 170-220°C, an equilibrium time of 20-50 min, and a sample weight of 0.5-3.0 g.

[0048] In an optional embodiment, the gas chromatography detection conditions include: the capillary column is a DB-624UI column; the heating program includes: starting at 85-115°C, maintaining for 1-10 min, heating to 120-150°C at 5-10°C / min, maintaining for 1-10 min, heating to 160-220°C at 5-10°C / min, maintaining for 8-15 min, heating to 250-270°C at 5-15°C / min, maintaining for 20-30 min; the injection port temperature is 250-270°C; the split ratio is 5-20:1; the column flow rate is 0.5-3.5 mL / min; the detector temperature is 250-270°C; the carrier gas is nitrogen with a purity ≥99.999%.

[0049] The beneficial effects of this application include:

[0050] The pretreatment system provided in the present application can effectively remove isooctanoic acid in the sample to be tested, avoid the interference of isooctanoic acid on the peak of isooctyl acrylate, and thus improve the accuracy of the test results. The corresponding detection method is simple, easy to operate, highly specific, highly accurate, and has good reproducibility, and the test results are accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0052] Figure 1 A schematic diagram of the structure of the pre-treatment system provided for this application;

[0053] Figure 2 This is a schematic diagram of the structure of the microporous fine mist agitator in the pre-treatment system of this application;

[0054] Figure 3 It is the peak schematic diagram in comparative example 1;

[0055] Figure 4 It is the peak schematic diagram in comparative example 2;

[0056] Figure 5 for Figure 4 A partial enlarged view of .

[0057] Icons: 1-extraction reaction equipment; 111-tank body; 1111-top surface; 1112-annular surface; 112-reaction chamber; 113-water inlet; 114-n-butanol inlet; 118-stannous octoate sample inlet; 119-merge inlet; 12-microporous fine mist agitator; 121-stirring head; 122-hollow stirring rod; 123-micropore; 13-heat conduction device; 131-opening; 132-material Material outflow channel; 133-ball valve; 134-heat transfer medium inlet; 135-heat transfer medium outlet; 21-first container; 22-second container; 25-fifth container; 26-selective container; 31-four-way valve A; 32-boosting pump; 33-two-way valve A; 34-three-way valve A; 35-two-way valve B; 36-three-way valve B; 37-three-way valve C; 38-three-way valve D; 39-three-way valve E; 40 -three-way valve F; 411-first main pipeline; 412-first branch; 413-second branch; 414-third branch; 415-fourth branch; 416-fifth branch; 417-second main pipeline; 418-third main pipeline; 419-sixth branch; 420-seventh branch; 421-fourth main pipeline; 422-eighth branch; 423-ninth branch; 424-fifth main pipeline; 425-tenth branch; 426-eleventh branch; 51-first condenser; 52-micropore pressure relief valve; 6-negative pressure extraction equipment; 61-magnetic stirrer; 62-extraction container; 621-extraction container inlet; 622-material outlet; 63-stirring bar; 64-second condenser; 641-vertical section; 642-inclined section; 65-first waste liquid collection container; 66-vacuum pump; 7-second waste liquid collection container. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0059] The following is a detailed description of the pre-treatment system and method for detecting the content of isooctyl acrylate (2-EHA) in stannous octoate provided in the present application.

[0060] After long-term research, the inventor creatively proposed that the reasons why the current conventional detection methods cannot effectively and accurately determine the content of isooctyl acrylate in stannous octoate mainly include:

[0061] A. The boiling points of isooctyl acid and isooctyl acrylate in stannous octoate differ by only 9°C, and isooctyl acid will have a front peak, which will cause strong interference to isooctyl acrylate. The boiling points of both (isooctyl acid and isooctyl acrylate) are around 220°C. It is difficult for isooctyl acrylate to reach gas-liquid equilibrium at conventional heating temperature.

[0062] B. Isooctyl acrylate will self-polymerize at 100°C. Simply increasing the temperature of the heating box of the headspace sampler will cause a more serious front peak of isooctyl acid. At the same time, high temperature will accelerate the self-polymerization of isooctyl acrylate, resulting in a low spike recovery rate.

[0063] Based on this, the present application proposes a pre-treatment system for detecting the content of isooctyl acrylate in stannous octoate (such as Figure 1 As shown), the system includes an extraction reaction device 1.

[0064] The extraction reaction equipment 1 comprises an extraction reaction container, a microporous fine mist agitator 12 and a heat conduction device 13 .

[0065] The extraction reaction container includes a tank body 111 having a reaction chamber 112, and a water inlet 113, an n-butanol inlet 114, a reaction solvent inlet (not shown), a cleaning solvent inlet (not shown), a protective gas inlet (not shown) and a stannous octoate sample inlet 118 are provided on the top of the tank body 111.

[0066] The microporous fine mist agitator 12 is disposed in the reaction chamber 112. The microporous fine mist agitator 12 includes a stirring head 121 and a hollow stirring rod 122. One end of the hollow stirring rod 122 is connected to the reaction solvent inlet, the cleaning solvent inlet and the protective gas inlet. The other end of the hollow stirring rod 122 is connected to the hollow stirring head 121. The surface of the hollow stirring head 121 is provided with micropores 123. Figure 2 shown.

[0067] The heat conducting device 13 is arranged on the periphery of the tank body 111 and is used to conduct heat to the material in the reaction chamber 112; an opening 131 is provided at the bottom of the heat conducting device 13, a material outflow channel 132 is formed between the bottom of the tank body 111 and the opening 131, and a ball valve 133 is provided at the opening 131.

[0068] For reference, the tank body 111 includes a top surface 1111 and an annular surface 1112 , the periphery of the top surface 1111 is connected to the top periphery of the annular surface 1112 , the top surface 1111 is a horizontal surface, and the annular surface 1112 is an arc surface.

[0069] By setting the annular surface 1112 as an arc surface, it is beneficial for the material to be fully extracted and the cleaning solvent to be fully cleaned.

[0070] In some optional embodiments, the top of the annular surface 1112 may have an angle of 5-20° with the vertical direction, such as 5°, 10°, 15° or 20°.

[0071] For reference, in the microporous mist agitator 12, the projection of the hollow agitator head 121 in the vertical direction is semicircular. The diameter of the semicircle can be 50-150 mm, such as 50 mm, 80 mm, 100 mm, 120 mm or 150 mm.

[0072] The diameter of the micropores 123 provided in the hollow stirring head 121 may be 1-3 mm, such as 1 mm, 1.5 mm, 2 mm, 2.5 mm or 3 mm.

[0073] The material of the microporous mist agitator 12 can be illustratively polytetrafluoroethylene or stainless steel, and the maximum pressure it can withstand can be about 200 bar.

[0074] For reference, the upper and lower parts of the heat conducting device 13 are respectively provided with a heat conducting medium inlet 134 and a heat conducting medium outlet 135. The heat conducting medium can be heat conducting silicone oil. Through the heat conducting medium inlet 134 and the heat conducting medium outlet 135, the circulation of the heat conducting medium can be achieved.

[0075] Furthermore, the pretreatment system further comprises a first container 21 for storing water, a second container 22 for storing n-butanol, a third container (not shown) for storing a reaction solvent, a fourth container (not shown) for storing a cleaning solvent, and a fifth container 25 for storing a protective gas (such as nitrogen);

[0076] The outlet of the first container 21 is connected to the water inlet 113 through a pipeline, the outlet of the second container 22 is connected to the n-butanol inlet 114 through a pipeline, the outlet of the third container is connected to the reaction solvent inlet through a pipeline, the outlet of the fourth container is connected to the cleaning solvent inlet through a pipeline, and the outlet of the fifth container 25 is connected to the protective gas inlet through a pipeline.

[0077] The outlet of the fifth container 25 is connected to the inlets of the first container 21 to the fourth container through pipelines; valves are provided on each connecting pipeline, among which the valve on the pipeline connecting the outlet of the fifth container 25 and the inlet of the second container 22 is a four-way valve, and the other port of the four-way valve is connected to the protective gas inlet through a pipeline.

[0078] In some preferred embodiments, the reactive solvent inlet, the cleaning solvent inlet and the protective gas inlet share the same inlet (the inlet is defined as the merged inlet 119 ).

[0079] When the reaction solvent inlet, the cleaning solvent inlet and the protective gas inlet share the same inlet, the pipeline connecting the other port of the four-way valve and the protective gas inlet, the pipeline connecting the outlet of the third container and the reaction solvent inlet, and the pipeline connecting the outlet of the fourth container and the cleaning solvent inlet are first merged into a main pipeline and then connected to the same common inlet. A booster pump 32 is provided on the main pipeline.

[0080] Preferably, the third container and the fourth container can be combined into one container (which can save cost and floor space), which is defined as the selective container 26. It should be noted that the storage solvent in the selective container 26 can also be replaced with other solvents or substances except the reaction solvent and the cleaning solvent according to specific needs.

[0081] In the above preferred embodiment, the outlet of the fifth container 25 is connected to the first main pipeline 411, and the end of the first main pipeline 411 away from the fifth container 25 is divided into a first branch 412, a second branch 413 and a third branch 414. The first branch 412 is connected to the inlet of the first container 21, the second branch 413 is connected to the inlet of the second container 22, and the third branch 414 is connected to the inlet of the selective container 26.

[0082] The first main pipeline 411 is provided with a two-way valve A33, the first branch 412 is provided with a three-way valve A34, the third branch 414 is provided with a two-way valve B35, and the second branch 413 is provided with a four-way valve A31. The three-way valve A34 is connected to the four-way valve A31 through a pipeline. The outlet of the selective container 26 is connected to the fourth branch 415, and the remaining opening of the four-way valve A31 is connected to the fifth branch 416; the end of the fourth branch 415 away from the selective container 26 and the end of the fifth branch 416 away from the four-way valve A31 merge into the second main pipeline 417, and the other end of the second main pipeline 417 is connected to the merged inlet 119. The second main pipeline 417 is provided with a three-way valve B36 and a booster pump 32 in sequence from the direction away from the tank body 111 to the direction close to the tank body 111.

[0083] Furthermore, a first condenser 51 is integrated on the top of the tank body 111 , and the top of the first condenser 51 is connected to the outlet of the second container 22 .

[0084] The outlet of the second container 22 is connected to the third main pipeline 418, and the other end of the third main pipeline 418 is divided into a sixth branch 419 and a seventh branch 420, wherein the sixth branch 419 is connected to the n-butanol inlet 114, and the seventh branch 420 is connected to the top of the first condenser 51. A three-way valve C37 is provided at the branch of the third main pipeline 418.

[0085] Preferably, a microporous pressure relief valve 52 is also provided on the top of the first condenser 51. According to the amount of protective gas filled into the tank body 111, the pressure is released through the microporous pressure relief valve 52. On the one hand, it can avoid the safety hazard caused by excessive pressure in the tank, and on the other hand, it can avoid the pressure in the tank being greater than the internal pressure of the microporous fine mist agitator 12, so that the material in the tank body 111 can reversely enter the microporous fine mist agitator 12.

[0086] Exemplarily, the height of the first condenser 51 may be 10-15 cm, such as 10 cm, 11 cm, 12 cm, 13 cm, 14 cm or 15 cm.

[0087] By setting the height of the first condenser 51 to 10-15 cm, a better condensation effect can be ensured, and n-butanol can be prevented from volatilizing from the top of the first condenser 51 under the heat conduction effect of the heat conduction device 13.

[0088] Furthermore, the above-mentioned pre-treatment system also includes a negative pressure extraction device 6.

[0089] The negative pressure extraction device 6 includes a magnetic stirrer 61 with weighing and heating functions, an extraction container 62 , a stirrer 63 , a second condenser 64 , a first waste liquid collection container 65 and a vacuum pump 66 .

[0090] The extraction container 62 is used to be placed on the platform of the magnetic stirrer 61, and the stirrer 63 is used to be placed in the extraction container 62. The extraction container 62 has an extraction container inlet 621 and a material outlet 622. The extraction container inlet 621 is connected to the opening 131 at the bottom of the heat conducting device 13, one end of the second condenser 64 is connected to the material outlet 622, and the other end of the second condenser 64 is connected to the inlet of the first waste liquid collection container 65. The first waste liquid collection container 65 is also connected to the vacuum pump 66.

[0091] Among them, the second condenser 64 includes a vertical section 641 and a downwardly inclined section 642, one end of the vertical section 641 is connected to the material outlet 622, the other end of the vertical section 641 is connected to one end of the inclined section 642, and the other end of the inclined section 642 is connected to the inlet of the first waste liquid collection container 65.

[0092] For reference, the height of the vertical section 641 may be 10-15 cm, such as 10 cm, 11 cm, 12 cm, 13 cm, 14 cm or 15 cm.

[0093] By providing the inclined section 642 , it is possible to prevent waste liquid from flowing back into the extraction container 62 and affecting the weighing value.

[0094] Furthermore, the pretreatment system further includes a second waste liquid collecting container 7, the inlet of the second waste liquid collecting container 7 is connected to the opening 131 at the bottom of the heat conducting device 13, and the outlet of the second waste liquid collecting container 7 is connected to the water inlet, the n-butanol inlet and the top of the first condenser 51.

[0095] Specifically, the opening 131 at the bottom of the heat conducting device 13 is connected to the fourth main pipeline 421, and the other end of the fourth main pipeline 421 is divided into an eighth branch 422 and a ninth branch 423, wherein the eighth branch 422 is connected to the extraction container inlet 621, and the ninth branch 423 is connected to the inlet of the second waste liquid collection container 7. A three-way valve D38 is provided at the branch of the fourth main pipeline 421.

[0096] The outlet of the second waste liquid collection container 7 is connected to the fifth main pipeline 424, and the other end of the fifth main pipeline 424 is divided into a tenth branch 425 and an eleventh branch 426, wherein the tenth branch 425 is connected to the pipeline connecting the outlet of the first container 21 and the water inlet 113 (a three-way valve E39 is provided at the connection), and the eleventh branch 426 is connected to the third main pipeline 418 (a three-way valve F40 is provided at the connection).

[0097] Correspondingly, the present application also provides a method for detecting the content of isooctyl acrylate in stannous octoate, comprising the following steps: using the above-mentioned pretreatment system to pre-treat the stannous octoate sample to be treated.

[0098] For reference, the pretreatment includes: adding stannous octoate sample, water and n-butanol into the tank body 111, passing the reactive solvent into the tank body 111 from the micropores 123 of the microporous fine mist agitator 12, and circulating the heat-conducting medium in the heat-conducting device 13, so that the material in the tank body 111 forms an emulsion; then standing until no bubbles are generated and the oil phase and the water phase are obviously separated, collecting the lower water phase in the second waste liquid collection container 7, collecting the upper oil phase in the extraction container 62, and discharging the n-butanol through the second condenser 64 to the first waste liquid collection container 65 under the heating action of the magnetic stirrer 61, and recording the final weight increase of the extraction container 62.

[0099] Specifically, the stannous octoate sample to be treated (mass is denoted as M 1) is added into the reaction chamber 112 of the tank body 111 through the stannous octoate sample inlet 118, the water in the first container 21 is passed into the reaction chamber 112 of the tank body 111 through the pipeline via the water inlet 113, and the n-butanol in the second container 22 is passed into the reaction chamber 112 of the tank body 111 through the pipeline via the n-butanol inlet 114; at the beginning, the solvent stored in the selective container 26 is a reactive solvent (such as sodium bicarbonate aqueous solution), which is pumped into the confluence inlet 119 through the pipeline and the booster pump 32, and then enters the hollow stirring head 121 through the hollow stirring rod 122, and is sprayed outward into the reaction chamber 112 during the stirring process.

[0100] In the above process, the volume ratio of water to n-butanol added into the tank 111 is 1:5-40, such as 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35 or 1:40, etc., or any other value within the range of 1:5-40.

[0101] It should be noted that if the volume ratio of water to n-butanol is less than 1:5, it is easy for stannous octoate to not be completely dissolved, forming an emulsion; if the volume ratio of water to n-butanol is greater than 1:40, it is easy for the mixed emulsion to have less water phase, and less isooctanoic acid dissolved in 80°C water to participate in the reaction.

[0102] The stirring speed of the microporous mist stirrer 12 can be 60-200 r / min, such as 60 r / min, 80 r / min, 100 r / min, 120 r / min, 150 r / min, 180 r / min or 200 r / min, or any other value within the range of 60-200 r / min.

[0103] It should be noted that the stirring speed of the microporous fine mist agitator 12 includes two working states: low speed and high speed. The low speed is 60-80r / min, which is suitable for stirring the sodium bicarbonate aqueous solution and the mixed emulsion reaction stage; if the stirring speed of the microporous fine mist agitator 12 is lower than 60r / min, it is easy to cause the sodium bicarbonate aqueous solution and the mixed emulsion to be mixed unevenly and react slowly; if the stirring speed of the microporous fine mist agitator 12 is higher than 80r / min, it is easy to bring gas into the solution to form bubbles, which is not conducive to the observation of bubbles at the end of the reaction; the high speed is 80-200r / min, which is suitable for the cleaning solvent to rinse the reaction chamber stage, and the cleaning solvent can completely clean the reaction chamber under high speed conditions.

[0104] Heat-conducting silicone oil is introduced into the heat-conducting medium inlet 134 , and the heat-conducting medium after heat exchange is output through the heat-conducting medium outlet 135 . The external heating device heats the output heat-conducting medium after heat exchange to the required temperature, and then recirculates it through the heat-conducting medium inlet 134 to the heat-conducting device 13 .

[0105] For reference, the temperature of the heat-conducting medium in the heat-conducting device 13 may be 80-115° C., such as 80° C., 85° C., 90° C., 95° C., 100° C., 105° C., 110° C. or 115° C., or any other value within the range of 80-115° C. Exemplarily, the heat-conducting medium may be heat-conducting silicone oil.

[0106] Under the above conditions, the material in the reaction chamber 112 is first in the form of an emulsion. When the mixed emulsion has no bubbles, it is left to stand until the oil phase and the water phase are clearly separated. The lower layer of water is discharged into the second waste liquid collection container 7 through a pipeline through the material outflow channel 132 between the bottom of the tank body 111 and the opening 131 at the bottom of the heat conduction device 13 (at this time, the valve set at the opening 131 is opened, and the channel connecting the three-way valve D38 and the extraction container inlet 621 is closed).

[0107] For reference, the standing time may be 30-120 min, such as 30 min, 60 min, 90 min or 120 min, or any other value within the range of 30-120 min.

[0108] Preferably, before recording the final weight increase of the extraction container 62, the method further includes: replacing the solvent stored in the selective container 26 with n-butanol, and then pumping the n-butanol into the confluence inlet 119 through a pipeline and a booster pump 32 (for adjusting the pressure), and then entering the hollow stirring head 121 through the hollow stirring rod 122, and spraying outward during the stirring process (preferably spraying in the form of fine mist, at this time the stirring speed of the microporous fine mist agitator 12 can be 200r / min) into the reaction chamber 112 to clean the residual material on the inner wall of the reaction chamber 112 (such as cleaning for 1-2min).

[0109] The washed eluent is combined with the oil phase and flows into the extraction container 62 through the three-way valve D38 (at this time, the channel connecting the three-way valve D38 and the second waste liquid collection container 7 is closed).

[0110] Furthermore, the protective gas in the fifth container 25 is directly introduced into the confluence inlet 119 through the pipeline and the booster pump 32, and then enters the hollow stirring head 121 through the hollow stirring rod 122 and is sprayed outward, so as to purge the residual liquid in the reaction chamber 112 into the extraction container 62 through the three-way valve D38 (at this time, the channel connecting the three-way valve D38 and the second waste liquid collection container 7 is closed). The weight measured by the magnetic stirrer 61 at this time is recorded.

[0111] Further, the vacuum pump 66 is turned on, and the magnetic stirrer 61 with weighing and heating functions is turned on at the same time, the temperature of the oil phase in the extraction container 62 is controlled to be about 118°C and the vacuum degree in the extraction container 62 is not less than -0.95MPa, such as -0.95MPa to -0.98MPa.

[0112] The evaporated n-butanol is condensed by the second condenser 64 and then enters the first waste liquid collection container 65 .

[0113] The mass M to be displayed by the magnetic stirrer 61 with weighing and heating function 2 When there is no more change, it means that the n-butanol in stannous octoate has been completely removed.

[0114] Furthermore, under the purge of protective gas, a cleaning solvent (including at least one of toluene, acetonitrile and acetone) can be used to clean the residual liquid in the solvent tank and pipeline.

[0115] It should be noted that during the above-mentioned use, the opening and closing conditions of the above-mentioned valves are normal capabilities and will not be elaborated on here.

[0116] In the above, the present application forms an emulsion of stannous octoate by using two solvents, water and n-butanol. Taking advantage of the fact that isooctanoic acid is soluble in 80°C water, while stannous octoate and isooctyl acrylate are not soluble, an aqueous sodium bicarbonate solution is used to neutralize the isooctanoic acid dissolved in water (i.e., to remove the isooctanoic acid), and the disappearance of bubbles is used to indicate the end point of the reaction. The n-butanol in the oil layer is subjected to negative pressure extraction, thereby achieving the purpose of removing isooctanoic acid in stannous octoate and avoiding the interference of isooctanoic acid on the peak of isooctyl acrylate.

[0117] Furthermore, the detection method of the present application also includes: mixing the stannous octoate obtained by pretreatment with an inhibitor and an internal standard, and then using headspace-gas chromatography to detect the content of isooctyl acrylate.

[0118] Specifically, the treated stannous octoate, inhibitor and internal standard are mixed evenly, added into a headspace bottle and sealed with a cover, heated and balanced for a period of time in a headspace sampler, and the upper gas in the headspace bottle is extracted and entered into a gas chromatograph for analysis, and quantified by the internal standard method.

[0119] Alternatively, the polymerization inhibitor includes methylhydroquinone and 2-tert-butylhydroquinone.

[0120] Among them, the dosage of methylhydroquinone can be 20-50ppm (such as 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm or 50ppm, etc.), and the dosage of 2-tert-butylhydroquinone can be 20-50ppm (such as 20ppm, 25ppm, 30ppm, 35ppm, 40ppm, 45ppm or 50ppm, etc.).

[0121] For reference, the detection conditions of the head space sampler may include: a heating box temperature of 160-210°C (such as 160°C, 170°C, 180°C, 190°C, 200°C or 210°C, etc.), a quantitative loop temperature of 160-210°C (such as 160°C, 170°C, 180°C, 190°C, 200°C or 210°C, etc.), a transmission line temperature of 170-220°C (such as 170°C, 180°C, 190°C, 200°C, 210°C or 220°C, etc.), an equilibrium time of 20-50min (such as 20min, 30min, 40min or 50min, etc.), and a sample weight of 0.5-3.0g (such as 0.5g, 1g, 1.5g, 2g, 2.5g or 3g, etc.).

[0122] For reference, the gas chromatography detection conditions may include: the capillary column is a DB-624UI column (such as 60m×320μm×1.8μm or equivalent); the temperature program includes: starting at 85-115°C (such as 85°C, 90°C, 95°C, 100°C, 105°C, 110°C or 115°C, etc.) and maintaining for 1-10min (such as 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min or 10min), increasing at 5-10°C / min (such as 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min); min, etc.), raise the temperature to 120-150℃ (such as 120℃, 130℃, 140℃ or 150℃, etc.), maintain for 1-10min (such as 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min or 10min, etc.), raise the temperature to 160-220℃ (such as 160℃, 170℃, 180℃, 190℃, 200℃, 210℃ or 220℃, etc.) at 5-10℃ / min (such as 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, etc.), maintain for 8-15min (such as 8min , 9min, 10min, 11min, 12min, 13min, 14min or 15min, etc.), heat up to 250-270℃ (such as 250℃, 255℃, 260℃, 265℃ or 270℃, etc.) at 5-15℃ / min (such as 5℃ / min, 8℃ / min, 10℃ / min, 12℃ / min or 15℃ / min, etc.), maintain for 20-30min (such as 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min or 30min, etc.); the injection port temperature is 250- 270°C (such as 250°C, 255°C, 260°C, 265°C or 270°C, etc.); the split ratio is 5-20:1 (such as 5:1, 8:1, 10:1, 12:1, 15:1, 18:1 or 20:1, etc.); the column flow rate is 0.5-3.5mL / min (such as 0.5mL / min, 1mL / min, 1.5mL / min, 2mL / min, 2.5mL / min, 3mL / min or 3.5mL / min, etc.); the detector temperature is 250-270°C (such as 250°C, 255°C, 260°C, 265°C or 270°C, etc.); the carrier gas is nitrogen with a purity of ≥99.999%.

[0123] It should be noted that the above-mentioned headspace-gas chromatography detection process and other parameters can refer to the relevant existing technologies, and will not be elaborated or limited in detail here.

[0124] The qualitative analysis of isooctyl acrylate (2-EHA) was determined by the retention time, and the quantitative analysis of isooctyl acrylate (2-EHA) was determined by the ratio of the peak area of ​​isooctyl acrylate (2-EHA) to the peak area of ​​n-heptane.

[0125] In the above operation, a standard working curve of 2-ethylhexyl acrylate (2-EHA) is first established; the content of 2-ethylhexyl acrylate (2-EHA) in the sample containing the internal standard and the inhibitor is detected by headspace-gas chromatography, and the content is calculated according to the obtained standard working curve.

[0126] In continuation of the above, this application uses a headspace injection method for the sample to be tested to avoid stannous octoate from entering the gas chromatography column and reduce the noise caused by co-extracts. Adding an inhibitor to the sample to be tested avoids the self-polymerization of isooctyl acrylate at high temperature and improves the recovery rate at different addition levels; the internal standard is used for detection, and the content is calculated by the ratio of the peak area of ​​isooctyl acrylate to the peak area of ​​the internal standard, avoiding the fluctuation of the peak area of ​​isooctyl acrylate caused by the size of the peak area of ​​the low-boiling point substance in the external standard method.

[0127] The detection method provided in the present application has strong specificity, high accuracy, good reproducibility, and accurate and reliable detection results. It can accurately determine the content of trace isooctyl acrylate (2-EHA) in stannous octoate, thereby improving the safety of consumer foam products.

[0128] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0129] The reagents used below include: isooctyl acrylate (2-EHA) (Aladdin purity 99.50%); n-heptane (Aladdin purity 99.50%); n-butanol (Aladdin purity 99.70%); methylhydroquinone (Aladdin purity 99.00%); 2-tert-butylhydroquinone (Aladdin purity 98.00%).

[0130] The instruments used included: headspace-gas chromatograph (Agilent 7697A-7820A); electronic balance (Changzhou Lucky Electronic Equipment Co., Ltd.).

[0131] Example 1

[0132] This embodiment provides a method for detecting the content of isooctyl acrylate in stannous octoate. The pretreatment system used is referred to the above content, and the operation steps are mainly referred to as follows:

[0133] (1) Purified water in the first container 21 and n-butanol in the second container 22 are introduced into the reaction chamber 112 of the tank body 111 from the water inlet 113 and the n-butanol inlet 114, respectively, and stannous octoate to be treated is added from the stannous octoate sample inlet 118. The addition ratio of purified water, n-butanol, and stannous octoate is 1:5:5, where the mass of stannous octoate is denoted as M 1 .

[0134] (2) The heat-conducting silicone oil at a temperature of 80° C. is introduced into the heat-conducting medium inlet 134, and the rotation speed of the microporous fine mist agitator 12 is 60 r / min. After the mixed solution becomes an emulsion, the reactive solvent (sodium bicarbonate aqueous solution) in the selective container 26 slowly flows out into the reaction chamber 112 through the micropores 123 in the microporous fine mist agitator 12.

[0135] (3) After the mixed emulsion has no bubbles, it is left to stand for 1 hour until the liquid is clearly stratified, and the lower layer of water is discharged into the second waste liquid collection container 7 through the material outflow channel 132 between the bottom of the tank body 111 and the opening 131 at the bottom of the heat conduction device 13 through the pipeline.

[0136] (4) Open the three-way valve C37 and rinse the inside of the condenser with n-butanol through the pipeline for 2-3 times. Add n-butanol to the selective container 26, and at the same time turn on the booster pump 32, adjust the pressure so that n-butanol is sprayed out from the microporous fine mist agitator 12 in the form of fine mist, and set the speed of the microporous fine mist agitator 12 to 200 r / min to rinse the inner wall of the extraction reactor for 2 minutes; the above n-butanol eluent is combined with the oil phase and transferred to the extraction container 62 through the three-way valve D38, and the mass change before and after is recorded.

[0137] (5) Open the four-way valve and the three-way valve B36 to allow nitrogen to be directly ejected from the micropores 123 in the microporous fine mist agitator 12 through the booster pump 32, and blow the residual liquid in the extraction reactor into the extraction container 62 through the pipeline.

[0138] (6) Turn on the vacuum pump 66 and simultaneously turn on the magnetic stirrer 61 with heating and weighing functions, and control the oil phase temperature in the extraction container 62 to be around 118° C. and the vacuum degree to be not less than -0.95 MPa.

[0139] (7) Wait for the magnetic stirrer 61 with weighing function to display the mass M 2 When there is no more change, it means that the n-butanol in stannous octoate has been completely removed.

[0140] (8) Adjust the three-way valve B36 so that the nitrogen in the fifth container 25 flows through the selective container 26 to the first container 21 and the second container 22, and finally to the second waste liquid collection container 7. Then add a cleaning solvent (toluene) to the selective container 26, and clean the residual liquid in each solvent tank and pipeline under the purge of nitrogen.

[0141] Further, after pre-processing, the subsequent detection process is carried out according to the following method:

[0142] A. Preparation of standard solution:

[0143] Preparation of internal standard stock solution containing polymerization inhibitor: n-heptane, methyl hydroquinone and 2-tert-butyl hydroquinone are accurately weighed (accurate to 0.0001g), and stannous octoate without 2-ethylhexyl acrylate (2-EHA) is used as solvent. The above stannous octoate without 2-ethylhexyl acrylate (2-EHA) has been treated by a pretreatment device to remove 2-ethylhexyl acrylate. Accurately prepare a 0.10% n-heptane stannous octoate stock solution, in which the addition amounts of methyl hydroquinone and 2-tert-butyl hydroquinone are both 30ppm.

[0144] Preparation of internal standard working solution containing isooctyl acrylate (2-EHA) and inhibitor: Accurately weigh isooctyl acrylate (2-EHA) (accurate to 0.0001g), use 0.10% stannous n-heptane octoate stock solution as solvent to prepare an internal standard working solution of isooctyl acrylate (2-EHA), the mass percentages of isooctyl acrylate (2-EHA) in the internal standard working solutions are 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09% and 0.10%, respectively.

[0145] B. Sample processing:

[0146] Accurately weigh 9.9900g of the pre-treated sample and 0.0100g of n-heptane, weigh about 0.0003g of methylhydroquinone and 2-tert-butylhydroquinone, add them to the round-bottom flask and stir evenly. Accurately weigh 2.0000g±0.1000g of the above stirred sample, add it to a 20mL headspace bottle, and use a capping device to clamp the bottle cap and the headspace bottle, and place it in the headspace injector.

[0147] C. Instrumental analysis:

[0148] a. Headspace sampler detection conditions are:

[0149] Heating box temperature: 210℃; quantitative loop temperature: 210℃; transfer line: 220℃; equilibrium time: 30min.

[0150] b. Gas chromatography detection conditions are:

[0151] Capillary column: DB-624UI, dimensions: 60m×320μm×1.8μm or equivalent; programmed temperature: initial temperature: 110℃ for 3min, increase to 120℃ at 5℃ / min, maintain for 2min, increase to 170℃ at 5℃ / min, maintain for 10min, increase to 250℃ at 15℃ / min, maintain for 25min; injection port temperature: 250℃; split ratio: 10:1; column flow rate: 1.0mL / min; detector: 250℃; carrier gas: nitrogen, with a purity of ≥99.999%.

[0152] D. Calculation:

[0153] The calculation formula ① for the content of isooctyl acrylate (2-EHA) in stannous octoate from which isooctyl acid has been removed is as follows:

[0154]

[0155] in:

[0156] W represents: the mass percentage of isooctyl acrylate (2-EHA);

[0157] S represents: isooctyl acrylate (2-EHA) peak area;

[0158] S 0 Indicates: peak area of ​​n-heptane;

[0159] M 0 Indicates: the mass of n-heptane added to the sample containing the internal standard in the headspace bottle, unit: g;

[0160] M represents: the amount of sample to be tested containing internal standard added to the headspace bottle, unit: g;

[0161] R f Indicates: Relative correction factor of 2-ethylhexyl acrylate (2-EHA).

[0162] Calculation of relative correction factor of 2-EHA:

[0163] The slope of the standard curve drawn is Rf, with the ratio of the peak area of ​​2-EHA to the peak area of ​​n-heptane as the abscissa and the mass ratio of 2-EHA to n-heptane as the ordinate.

[0164] The calculation formula of the content of isooctyl acrylate (2-EHA) in stannous octoate is as follows:

[0165] Among them, M 1 is the weight of the sample to be tested, M 2It is the weight of stannous octoate after removing n-butanol, which is finally weighed by the magnetic stirrer 61 with heating and weighing functions.

[0166] Example 2

[0167] This example is the determination of the correction factor of isooctyl acrylate.

[0168] Preparation of internal standard stock solution containing polymerization inhibitor: n-heptane, methyl hydroquinone and 2-tert-butyl hydroquinone are accurately weighed (accurate to 0.0001g), and stannous octoate without 2-ethylhexyl acrylate (2-EHA) is used as solvent. The above stannous octoate without 2-ethylhexyl acrylate (2-EHA) has been treated by a pretreatment device to remove 2-ethylhexyl acrylate. Accurately prepare a 0.10% n-heptane stannous octoate stock solution, in which the addition amounts of methyl hydroquinone and 2-tert-butyl hydroquinone are both 30ppm.

[0169] Preparation of internal standard working solution containing isooctyl acrylate (2-EHA) and inhibitor: Accurately weigh isooctyl acrylate (2-EHA) (accurate to 0.0001g), use 0.10% stannous n-heptane octoate stock solution as solvent to prepare an internal standard working solution of isooctyl acrylate (2-EHA), the mass percentages of isooctyl acrylate (2-EHA) in the internal standard working solutions are 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09% and 0.10%, respectively.

[0170] Accurately weigh 2.0000 g ± 0.1000 g of the internal standard working solution containing isooctyl acrylate (2-EHA) and inhibitor, add it to a 20 mL headspace bottle, and use a capping device to clamp the bottle cap and the headspace bottle, and place it in the headspace sampler, where the headspace-gas chromatography instrument conditions are set according to the aforementioned instrument analysis part.

[0171] Then the obtained chromatogram was analyzed and processed, and the ratio of the peak area of ​​2-ethylhexyl acrylate (2-EHA) to the peak area of ​​n-heptane was used as the abscissa, and the ratio of the mass of 2-ethylhexyl acrylate (2-EHA) to the mass of n-heptane was used as the ordinate to establish the standard curve of 2-ethylhexyl acrylate (2-EHA): Y = 1.8428X; the correlation coefficient R 2 =0.9997.

[0172] Example 3

[0173] This example analyzes the experiment of determining the content of isooctyl acrylate (2-EHA) in different types of tin metal catalysts.

[0174] Test samples: T-9 (A1-A20); T-190 (A20-A25); T-900 (A25-A30);

[0175] Among them: T-9 is a stannous octoate sample, T-190 and T-900 are tin catalysts of different processes. The contents of isooctanoic acid in the above different types of tin metal catalysts are shown in Table 1.

[0176] Table 1 Content of isooctanoic acid in 30 batches of tin metal catalysts

[0177]

[0178]

[0179] Accurately weigh 9.9900g of the pre-treated sample and 0.0100g of n-heptane, weigh about 0.0003g of methylhydroquinone and 2-tert-butylhydroquinone, add them to the round-bottom flask, and stir evenly. Accurately weigh 2.0000g±0.1000g of the above stirred sample, add it to a 20mL headspace bottle, and use a capping device to clamp the bottle cap and the headspace bottle, and place it in the headspace injector, where the headspace-gas chromatography instrument conditions are set according to the aforementioned instrument analysis part.

[0180] The obtained chromatogram was then analyzed and processed, and the ratio of the peak area of ​​2-ethylhexyl acrylate (2-EHA) to the peak area of ​​n-heptane in the sample was substituted into calculation formulas ① and ② to obtain the mass percentage of the sample in 2-ethylhexyl acrylate (2-EHA). The calculation results are shown in Table 2.

[0181] Table 2 Content of 2-EHA in 30 batches of tin metal catalysts

[0182]

[0183]

[0184] Example 4

[0185] This example analyzes the parallel experiment of determining the content of isooctyl acrylate (2-EHA) in the same type of tin metal catalyst.

[0186] Accurately weigh 9.9900g of T-9 sample and 0.0100g of n-heptane after treatment by the pretreatment device, weigh about 0.0003g of methylhydroquinone and 2-tert-butylhydroquinone, add them to the round-bottom flask, and stir evenly. Accurately weigh 2.0000g±0.1000g of the above stirred sample, add it to a 20mL headspace bottle, and use a capping device to clamp the bottle cap and the headspace bottle, and place it in the headspace injector, where the headspace-gas chromatography instrument conditions are set according to the aforementioned instrument analysis part.

[0187] The obtained chromatogram was then analyzed and processed, and the ratio of the peak area of ​​2-ethylhexyl acrylate (2-EHA) to the peak area of ​​n-heptane in the sample was substituted into calculation formulas ① and ② to obtain the mass percentage of the sample in 2-ethylhexyl acrylate (2-EHA). The calculation results were retained to 3 significant figures, as shown in Table 3.

[0188] Table 3 Parallel experiment on the content of 2-EHA in the same type of tin metal catalyst

[0189]

[0190] Example 5

[0191] In this example, the linear range and minimum detection limit of isooctyl acrylate (2-EHA) were analyzed (the specific test conditions were the same as those in the instrument analysis section above). The linear range of isooctyl acrylate (2-EHA) was 0.01-0.10%, the correlation could reach 0.9996, and the detection limit was 0.002%, as shown in Table 4.

[0192] Table 4 Linear range, correlation coefficient (R) and limit of quantification (LOQ) of 2-ethylhexyl acrylate (2-EHA)

[0193] sequence Target Linear range (%) <![CDATA[R 2 ]]> LOQ(%) 1 2-Ethylhexyl acrylate (2-EHA) 0.01～0.10 0.9996 0.002

[0194] Example 6

[0195] In this example, the precision and recovery rate of detection and separation using the present invention are analyzed (the specific test conditions are the same as those in the above instrument analysis section).

[0196] Using stannous octoate containing 0.032% isooctyl acrylate as the sample matrix, spike recovery experiments were carried out. The addition levels of isooctyl acrylate were 0.02%, 0.04%, and 0.06%. According to the pretreatment and instrument analysis of this study, 8 repeated experiments were performed at each level. The average recovery rate could reach more than 95%, and the relative standard deviation was less than 5%, as shown in Table 5.

[0197] Table 5 Average recovery and relative standard deviation of 2-EHA

[0198]

[0199]

[0200] Comparative Example 1

[0201] Taking Example 1 as an example, this comparative example is a spectrum comparison of stannous octoate that has not been treated by the pretreatment system of the present application and the spectrum comparison of stannous octoate that has been treated by the pretreatment device of the present application to remove isooctanoic acid (the other conditions are the same as those of Example 1), see Figure 3 .

[0202] Figure 3 M represents the isooctanoic acid peak that has not been treated by the pretreatment system of this application; N represents the isooctanoic acid peak that has been treated by the pretreatment system of this application, and N has overlapped with the baseline.

[0203] It can be seen from the figure that the peak of isooctanoic acid disappears after being treated by the pretreatment device of the present application, that is, the pretreatment device of the present application can completely remove isooctanoic acid.

[0204] Comparative Example 2

[0205] Taking Example 1 as an example, this comparative example examines the effect of the inhibitor by observing the change in the peak area of ​​isooctyl acrylate when the sample to be tested is not added with an inhibitor and when the sample is added with an inhibitor. The other conditions are the same as those in Example 1. The corresponding spectra are shown in FIG. Figure 4 and Figure 5 shown.

[0206] Figure 5 Here, M represents the peak of isooctyl acrylate when a polymerization inhibitor is added; N represents the peak of isooctyl acrylate when no polymerization inhibitor is added.

[0207] Depend on Figure 4 and Figure 5 By comparison, it can be seen that when no polymerization inhibitor is added, the peak of isooctyl acrylate is small, but after adding the polymerization inhibitor, the peak of isooctyl acrylate becomes significantly larger.

[0208] In summary, the present application uses two solvents, water and n-butanol, to form an emulsion of stannous octoate. Taking advantage of the fact that isooctanoic acid is soluble in 80°C water, while stannous octoate and isooctyl acrylate are not soluble, an aqueous sodium bicarbonate solution is used to neutralize the isooctanoic acid dissolved in water, and the disappearance of bubbles is used to indicate the end point of the reaction. The n-butanol in the oil layer is extracted under negative pressure, thereby achieving the purpose of removing isooctanoic acid from stannous octoate and avoiding the interference of isooctanoic acid on the peak of isooctyl acrylate. The headspace injection pretreatment method is used for the sample to be tested, which avoids stannous octoate from entering the gas chromatography column and reduces the noise caused by the co-extracts; an inhibitor is added to the sample to be tested, which avoids the self-polymerization of isooctyl acrylate at high temperature and improves the recovery rate at different addition levels; the internal standard is used for detection, and the content is calculated by the ratio of the peak area of ​​isooctyl acrylate to the peak area of ​​the internal standard, which avoids the fluctuation of the peak area of ​​isooctyl acrylate by the size of the peak area of ​​the low-boiling point substance in the external standard method.

[0209] This method has the characteristics of strong specificity, high accuracy, good reproducibility, and accurate and reliable test results. It can accurately determine the content of trace isooctyl acrylate (2-EHA) in stannous octoate, thereby improving the safety of consumers' foam product use.

[0210] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pretreatment system for detecting the content of isooctyl acrylate in stannous octoate, characterized in that: Including extraction reaction equipment; The extraction reaction equipment comprises an extraction reaction container, a microporous mist agitator and a heat conduction device; The extraction reaction container comprises a tank body having a reaction chamber, and a water inlet, an n-butanol inlet, a reaction solvent inlet, a cleaning solvent inlet, a protective gas inlet and a stannous octoate sample inlet are arranged on the top of the tank body; The microporous fine mist agitator is arranged in the reaction chamber, and the microporous fine mist agitator comprises a stirring head and a hollow stirring rod, one end of the hollow stirring rod is connected to the reaction solvent inlet, the cleaning solvent inlet and the protective gas inlet, and the other end of the hollow stirring rod is connected to the hollow stirring head, and micropores are opened on the surface of the hollow stirring head; The heat conducting device is arranged on the outer periphery of the tank body and is used to conduct heat to the material in the reaction chamber; an opening is arranged at the bottom of the heat conducting device, a material outflow channel is formed between the bottom of the tank body and the opening, and a valve is arranged at the opening; The pretreatment system further comprises a first container for storing water, a second container for storing n-butanol, a third container for storing a reactive solvent, a fourth container for storing a cleaning solvent, and a fifth container for storing a protective gas; The outlet of the first container is connected to the water inlet through a pipeline, the outlet of the second container is connected to the n-butanol inlet through a pipeline, the outlet of the third container is connected to the reactive solvent inlet through a pipeline, the outlet of the fourth container is connected to the cleaning solvent inlet through a pipeline, and the outlet of the fifth container is connected to the protective gas inlet through a pipeline; A first condenser is also integrated on the top of the tank body, and the top of the first condenser is connected to the outlet of the second container; The pretreatment system also includes a negative pressure extraction device; the negative pressure extraction device includes a magnetic stirrer with weighing and heating functions, an extraction container, a stirrer, a second condenser, a first waste liquid collection container and a vacuum pump; The extraction container is used to be placed on the platform of the magnetic stirrer, the stirrer is used to be placed in the extraction container, the extraction container has an extraction container inlet and a material outlet, the extraction container inlet is connected to the opening at the bottom of the heat conduction device, one end of the second condenser is connected to the material outlet, the other end of the second condenser is connected to the inlet of the first waste liquid collection container, and the first waste liquid collection container is also connected to a vacuum pump.

2. The pre-treatment system according to claim 1, characterized in that: The tank body comprises a top surface and an annular surface, the periphery of the top surface is connected to the periphery of the top end of the annular surface, the top surface is a horizontal surface, and the annular surface is an arc surface.

3. The pre-treatment system according to claim 2, characterized in that: The top of the annular surface has an angle of 5-20° with the vertical direction.

4. The pre-treatment system according to claim 1, characterized in that: In the microporous fine mist agitator, the projection of the hollow agitator head in the vertical direction is semicircular.

5. The pre-treatment system according to claim 4, characterized in that: The diameter of the semicircle is 50-150 mm.

6. The pre-treatment system according to claim 5, characterized in that: The diameter of the micropores provided in the hollow stirring head is 1-3 mm.

7. The pre-treatment system according to claim 1, characterized in that: The reactive solvent inlet, the cleaning solvent inlet and the protective gas inlet share the same inlet.

8. The pre-treatment system according to claim 7, characterized in that: The outlet of the fifth container is connected to the inlets of the first container to the fourth container through pipelines respectively; a valve is provided on each connecting pipeline, wherein the valve on the pipeline connecting the outlet of the fifth container and the inlet of the second container is a four-way valve, and the other port of the four-way valve is connected to the protective gas inlet through a pipeline.

9. The pre-treatment system according to claim 8, characterized in that: When the reaction solvent inlet, the cleaning solvent inlet and the protective gas inlet share the same inlet, the pipeline connecting the other port of the four-way valve and the protective gas inlet, the pipeline connecting the outlet of the third container and the reaction solvent inlet, and the pipeline connecting the outlet of the fourth container and the cleaning solvent inlet are first merged into a main pipeline and then connected to the common inlet, and a booster pump is provided on the main pipeline.

10. The pre-treatment system according to claim 1, characterized in that: A microporous pressure relief valve is also provided on the top of the first condenser.

11. The pre-treatment system according to claim 1, characterized in that: The height of the first condenser is 10-15 cm.

12. The pre-treatment system according to claim 1, characterized in that: The upper part and the lower part of the heat conduction device are respectively provided with a heat conduction medium inlet and a heat conduction medium outlet.

13. The pre-treatment system according to claim 1, characterized in that: The second condenser includes a vertical section and a downwardly inclined section, one end of the vertical section is connected to the material outlet, the other end of the vertical section is connected to one end of the inclined section, and the other end of the inclined section is connected to the inlet of the first waste liquid collection container.

14. The pre-treatment system according to claim 13, characterized in that: The height of the vertical section is 10-15 cm.

15. The pre-treatment system according to claim 1, characterized in that: The pretreatment system also includes a second waste liquid collection container, the inlet of the second waste liquid collection container is connected to the opening at the bottom of the heat conduction device, and the outlet of the second waste liquid collection container is connected to the water inlet, the n-butanol inlet and the top of the first condenser.

16. A method for detecting the content of isooctyl acrylate in stannous octoate, characterized in that: The method comprises the following steps: using the pretreatment system described in any one of claims 1 to 15 to pretreat the stannous octoate sample to be treated.

17. The method according to claim 16, characterized in that Pre-treatment includes: Add stannous octoate sample, water and n-butanol into the tank body, pass the reactive solvent into the tank body from the micropores of the microporous fine mist agitator, and circulate the heat-conducting medium in the heat-conducting device until no bubbles are generated in the material in the tank body; Then let it stand until the oil phase and the water phase are clearly separated, collect the lower water phase into the second waste liquid collection container, collect the upper oil phase into the extraction container, and discharge the n-butanol into the first waste liquid collection container through the second condenser under the heating of the magnetic stirrer, and record the final weight increase of the extraction container.

18. The method according to claim 17, characterized in that Before recording the final weight increase of the extraction container, the method also includes firstly passing a cleaning solvent into the tank body from the micropores of the microporous fine mist agitator to rinse the reaction chamber, and then passing a protective gas into the tank body from the micropores of the microporous fine mist agitator to purge the residual liquid in the reaction chamber into the extraction container.

19. The method according to claim 17, characterized in that In the tank body, the volume ratio of water to n-butanol is 1:5-40.

20. The method according to claim 17, characterized in that The reaction solvent includes a sodium bicarbonate aqueous solution, and the cleaning solvent includes at least one of toluene, acetonitrile and acetone.

21. The method according to claim 17, characterized in that The stirring speed of the microporous fine mist agitator is 60-200r / min.

22. The method according to claim 17, characterized in that The temperature of the heat conducting medium in the heat conducting device is 80-115°C.

23. The method according to claim 22, characterized in that The heat conducting medium is heat conducting silicone oil.

24. The method according to claim 17, characterized in that The standing time is 30-120 minutes.

25. The method according to claim 17, characterized in that Also includes: The stannous octoate obtained by pretreatment is mixed with an inhibitor and an internal standard, and then the content of isooctyl acrylate is detected by headspace-gas chromatography.

26. The method according to claim 25, characterized in that The polymerization inhibitor includes methylhydroquinone and 2-tert-butylhydroquinone.

27. The method according to claim 26, characterized in that The dosage of the methylhydroquinone is 20-50 ppm, and the dosage of the 2-tert-butylhydroquinone is 20-50 ppm.

28. The method according to claim 25, characterized in that The detection conditions of the head space sampler include: the temperature of the heating box is 160-210°C, the temperature of the quantitative loop is 160-210°C, the temperature of the transmission line is 170-220°C, the equilibrium time is 20-50min, and the sample weight is 0.5-3.0g.

29. The method according to claim 25, characterized in that The gas chromatography detection conditions include: the capillary column is a DB-624UI column; the temperature program includes: starting at 85-115°C and maintaining for 1-10 minutes, heating to 120-150°C at 5-10°C / min, maintaining for 1-10 minutes, heating to 160-220°C at 5-10°C / min, maintaining for 8-15 minutes, heating to 250-270°C at 5-15°C / min, maintaining for 20-30 minutes; the injection port temperature is 250-270°C; the split ratio is 5-20:1; the column flow rate is 0.5-3.5mL / min; the detector temperature is 250-270°C; the carrier gas is nitrogen with a purity of ≥99.999%.

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