CN113960239B - Method for detecting content of methyltrimethoxysilane by internal standard method - Google Patents
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- BFXIKLCIZHOAAZ-UHFFFAOYSA-N methyltrimethoxysilane Chemical compound CO[Si](C)(OC)OC BFXIKLCIZHOAAZ-UHFFFAOYSA-N 0.000 title claims abstract description 96
- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000010813 internal standard method Methods 0.000 title claims abstract description 13
- 239000012086 standard solution Substances 0.000 claims abstract description 39
- 238000001514 detection method Methods 0.000 claims abstract description 25
- 239000000243 solution Substances 0.000 claims abstract description 24
- 238000002347 injection Methods 0.000 claims abstract description 22
- 239000007924 injection Substances 0.000 claims abstract description 22
- 239000000126 substance Substances 0.000 claims abstract description 19
- 238000004587 chromatography analysis Methods 0.000 claims abstract description 4
- 239000002904 solvent Substances 0.000 claims description 24
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 17
- 239000004202 carbamide Substances 0.000 claims description 17
- 238000005303 weighing Methods 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 15
- 239000007789 gas Substances 0.000 claims description 12
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 12
- CPUDPFPXCZDNGI-UHFFFAOYSA-N triethoxy(methyl)silane Chemical compound CCO[Si](C)(OCC)OCC CPUDPFPXCZDNGI-UHFFFAOYSA-N 0.000 claims description 8
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000012417 linear regression Methods 0.000 claims description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- 238000003988 headspace gas chromatography Methods 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 2
- YYLGKUPAFFKGRQ-UHFFFAOYSA-N dimethyldiethoxysilane Chemical compound CCO[Si](C)(C)OCC YYLGKUPAFFKGRQ-UHFFFAOYSA-N 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 230000003472 neutralizing effect Effects 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 230000000630 rising effect Effects 0.000 claims description 2
- NBXZNTLFQLUFES-UHFFFAOYSA-N triethoxy(propyl)silane Chemical compound CCC[Si](OCC)(OCC)OCC NBXZNTLFQLUFES-UHFFFAOYSA-N 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 abstract description 14
- 238000003786 synthesis reaction Methods 0.000 abstract description 13
- 238000004458 analytical method Methods 0.000 abstract description 2
- 239000012043 crude product Substances 0.000 description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 10
- WQDUMFSSJAZKTM-UHFFFAOYSA-N Sodium methoxide Chemical compound [Na+].[O-]C WQDUMFSSJAZKTM-UHFFFAOYSA-N 0.000 description 10
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 10
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 238000006136 alcoholysis reaction Methods 0.000 description 5
- 239000006227 byproduct Substances 0.000 description 5
- 239000000460 chlorine Substances 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 238000006386 neutralization reaction Methods 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 229910052801 chlorine Inorganic materials 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- GYQKYMDXABOCBE-UHFFFAOYSA-N chloro-dimethoxy-methylsilane Chemical compound CO[Si](C)(Cl)OC GYQKYMDXABOCBE-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000010606 normalization Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- MPNXSZJPSVBLHP-UHFFFAOYSA-N 2-chloro-n-phenylpyridine-3-carboxamide Chemical compound ClC1=NC=CC=C1C(=O)NC1=CC=CC=C1 MPNXSZJPSVBLHP-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- JJQZDUKDJDQPMQ-UHFFFAOYSA-N dimethoxy(dimethyl)silane Chemical compound CO[Si](C)(C)OC JJQZDUKDJDQPMQ-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004817 gas chromatography Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000012074 organic phase Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000008096 xylene Substances 0.000 description 2
- 230000005526 G1 to G0 transition Effects 0.000 description 1
- 238000002479 acid--base titration Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- -1 chlorine ions Chemical class 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 235000019441 ethanol Nutrition 0.000 description 1
- 238000010812 external standard method Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000007530 organic bases Chemical class 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000002990 reinforced plastic Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 239000004945 silicone rubber Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/88—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/16—Injection
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N2030/022—Column chromatography characterised by the kind of separation mechanism
- G01N2030/025—Gas chromatography
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N2030/042—Standards
- G01N2030/045—Standards internal
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/88—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
- G01N2030/8809—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample
- G01N2030/884—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample organic compounds
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- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
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- Pathology (AREA)
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Abstract
The invention relates to the technical field of analysis and test, and particularly discloses a method for detecting the content of methyltrimethoxysilane in methyltrimethoxysilane synthesis by using an internal standard method of headspace sampler sample injection, which comprises the following steps: preparing a solution A: comprises methyltrimethoxysilane standard solution, internal standard solution and standard curve series solution; B. performing gas chromatographic analysis on the standard curve solution; C. establishment of a standard curve: taking the percentage of the object to be detected and the total substance as an abscissa x, and the ratio of the peak areas of the object to be detected and the internal standard substance as an ordinate y, so as to obtain a standard curve, wherein the standard curve forcedly passes through an origin; D. after the sample to be detected is pretreated, the sample is put into a headspace bottle, and gas chromatographic analysis and detection are carried out by adopting a headspace sample injection mode. The invention has the advantages of simple method, short detection period, better repeatability and high precision.
Description
Technical Field
The invention belongs to the technical field of analysis, and particularly relates to a method for detecting the content of methyltrimethoxysilane in methyltrimethoxysilane synthesis by using an internal standard method of headspace sampler sample injection.
Background
Methyltrimethoxysilane (CH) 3 Si(CH 3 O) 3 ) Is colorless transparent liquid with density of 0.95-0.96g/cm 3 Refractive index is 1.367-1.370, is easy to absorb moisture, and pH is in the range of 6.5-7 at normal temperature.
Methyltrimethoxysilane is widely used as a cross-linking agent of room temperature vulcanized silicone rubber, a glass fiber surface treating agent and an external agent for reinforced plastic laminates, so as to improve the mechanical strength, heat resistance and moisture resistance of the products. The current preparation methods mainly comprise an alcoholysis method and a solvent method.
Patent application number 200810048996.8 discloses a method for preparing methyltrimethoxysilane by double-tower alcoholysis, which can generate byproducts such as hydrogen chloride, methyldimethoxychlorosilane and the like in the preparation process, and the subsequent process needs to use sodium methoxide for neutralization so as to remove chloride ions in the product. Since the chlorine content in methyldimethoxychlorosilane cannot be measured in precipitation titration or acid-base titration, if the chlorine content in the portion cannot be accurately measured, the quality of the required sodium methoxide cannot be accurately calculated in the neutralization process. If the subsequent process is carried out under the alkaline condition with excessive sodium methoxide, the side reaction of methyltrimethoxysilane can be increased sharply, so that the yield is greatly reduced; if the sodium methoxide is not added in a sufficient amount, chlorine ions cannot be removed, and the quality of the final product is affected.
DOI 10.3969/j.issn.1009-4369.2005.05.006 describes a method for preparing methyltrimethoxysilane by a solvent method, which introduces solvents such as xylene into a crude product, and besides problems generated in an alcoholysis method, the methyltrimethoxysilane and the solvents such as xylene cannot be well separated on a chromatographic column due to polarity, material properties and the like, so that the quantitative determination of the crude product is greatly interfered, and the subsequent acid removal process is influenced.
At present, the content of a crude methyltrimethoxysilane product in the methyltrimethoxysilane synthesis process mainly adopts a normalization method, the method relies on an FID detector, although the method is simpler, in actual production, the crude product contains a large amount of HCl, if the crude product is directly injected into a gas chromatograph for detection, the sample inlet, a liner tube and a detector of the instrument are greatly damaged, the stationary phase of a chromatographic column is damaged, the service life of the instrument and each component is influenced, the response factor difference among the components is larger in the gas chromatograph, in the detection process of the FID detector, the HCl overflows along with heating, peak shape distortion is caused, bulge, tailing peak and other conditions occur, and the content of byproducts and solvents cannot be accurately known, so that the content of methyltrimethoxysilane cannot be accurately measured by the simple area normalization method, the existing production requirements cannot be met, and the subsequent process is greatly influenced.
Because methyltrimethoxysilane is hygroscopic and is easily hydrolyzed, an organic base is used during the neutralization process to avoid the generation of water. Sodium methoxide is not suitable as a neutralizer for detecting a crude product because it allows the removal of an acid of the crude product while allowing the formation of an incompletely substituted chloride ion to proceed to methyltrimethoxysilane. Urea does not react with methyltrimethoxysilane, ammonia produced by neutralization does not need to be filtered to remove byproducts, the urea is solid at normal temperature, and NH is produced by reaction with hydrogen chloride 4 Cl has a melting point (340 ℃) which is very different from the boiling point (101 ℃) of methyltrimethoxysilane, and can not volatilize into a detection system in a headspace sampler, so that the urea can be used for removing HCl in a methyltrimethoxysilane crude product, and meanwhile, a chromatographic column is not polluted in the detection process and new impurities are not introduced.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a method for detecting the content of methyltrimethoxysilane in methyltrimethoxysilane synthesis by using an internal standard method of headspace sampler sample injection.
A method for detecting the content of methyltrimethoxysilane in methyltrimethoxysilane synthesis by using an internal standard method of headspace sampler sample injection comprises the following specific steps:
(1) Preparing a methyltrimethoxysilane standard solution: firstly, adding a certain amount of solvent into a 25mL volumetric flask, then accurately weighing a certain amount of methyltrimethoxysilane into the volumetric flask, fixing the volume to a scale mark by using the solvent, and shaking uniformly.
(2) Preparing an internal standard solution: accurately weighing a certain amount of internal standard substance in a 25mL volumetric flask, fixing the volume to a scale mark by using a solvent, and shaking uniformly.
(3) Drawing a standard curve: and respectively weighing the methyltrimethoxysilane standard solution and the internal standard solution, mixing the methyltrimethoxysilane standard solution and the internal standard solution in a 25mL volumetric flask, fixing the volume to a scale mark by using a solvent to obtain standard curve solutions, preparing at least more than 5 standard curve solutions, then adopting headspace sample injection to prepare the solution, detecting by using a gas chromatograph to obtain corresponding peak areas, and drawing a standard curve according to the peak areas of the contents of the samples.
(4) Determination of methyltrimethoxysilane samples: taking a sample to be detected, adding a certain amount of urea into a 25mL volumetric flask, regulating the pH of the solution to be within a range of 6-7 (because the crude product to be detected has strong acidity, the acid value can reach 150mgKOH/g at most, if the crude product is directly injected into a chromatograph to cause serious damage to a chromatographic column, a neutralizing agent is needed to be added to carry out acid removal treatment), adding an internal standard substance standard solution, and after the internal standard substance standard solution is uniformly shaken to a constant volume by a solvent, carrying out headspace gas chromatography detection under the chromatographic condition in the step (3), obtaining the peak area, and obtaining the methyltrimethoxysilane content according to the drawn standard curve.
The solvent is any one of absolute ethyl alcohol, n-hexane and n-heptane.
The internal standard is any one or more of methyltriethoxysilane, propyltriethoxysilane and dimethyldiethoxysilane. The concentration of the internal standard substance is 0.5-1 g/L.
The neutralizer is urea.
The correlation coefficient R in the linear regression equation 2 ≥0.999。
The detection conditions are as follows: the initial temperature of the headspace sampler is 35 ℃, the heating rate is 10 ℃/min, the temperature is raised to 110 ℃, and the headspace sampler is kept for 10min; the nitrogen flow rate of the gas chromatograph is 1.5mL/min, the hydrogen flow rate is 30mL/min, the air flow rate is 400mL/min, and the column box adopts a temperature programming mode: maintaining for 2min in an initial environment at 50 ℃ with the temperature rising rate of: heating to 180 ℃ at 20 ℃/min, and keeping for 10min; sample injection amount is 0.4 mu L, a split flow mode is adopted, and the separation ratio is 50:1, the temperature of the sample inlet is 250 ℃, and the temperature of the detector is 260 ℃.
The invention has high precision, good reproducibility, high accuracy and good repeatability, can realize direct detection of samples, avoid the influence of HCl on the service life of an instrument and the influence on the peak emergence of substances, accurately know the chlorine content of incomplete alcoholysis, adopts headspace sample injection, and can volatilize trimethyl ammonium chloride and other organic phases into a detection system after headspace sample injection because urea is added, which is usually solid and can be dissolved in organic solvents such as alcohol and ketone, and react with HCl to generate ammonium chloride, and the headspace sample injection can lead trimethyl ammonium chloride and other organic phases to volatilize into the detection system, and the headspace bottle can not enter the detection system, namely substances such as urea and the like can not enter a chromatographic column, so that the chromatographic column causes pollution, the service life of the instrument can be prolonged, the use precision of the instrument can be ensured, and great convenience is brought to a more subsequent process.
Drawings
FIG. 1 is a standard curve with methyltriethoxysilane as an internal standard.
FIG. 2 is a gas chromatogram using methyltriethoxysilane as an internal standard.
In fig. 1, the abscissa represents the measured substance and the percentage of the total substance, and the ordinate represents the ratio of the peak areas of the measured substance and the internal standard substance.
Detailed description of the preferred embodiments
A method for detecting the content of methyltrimethoxysilane in methyltrimethoxysilane synthesis by using an internal standard method of headspace sampler sample injection comprises the following specific steps:
(1) Preparing a methyltrimethoxysilane standard solution: firstly, adding a certain amount of solvent into a 25mL volumetric flask, then accurately weighing a certain amount of methyltrimethoxysilane in the volumetric flask, fixing the volume to a scale mark by using the solvent, and shaking uniformly;
(2) Preparing an internal standard solution: accurately weighing a certain amount of internal standard substance in a 25mL volumetric flask, fixing the volume to a scale mark by using a solvent, and shaking uniformly.
(3) Drawing a standard curve: respectively weighing the methyltrimethoxysilane standard solution and the internal standard solution, mixing the methyltrimethoxysilane standard solution and the internal standard solution in a 25mL volumetric flask, fixing the volume to a scale mark by using a solvent to obtain standard curve solutions, preparing at least more than 5 standard curve solutions, then adopting headspace sample injection to prepare the solution, detecting by using a gas chromatograph to obtain corresponding peak areas, and drawing a standard curve according to the peak areas of the contents of the samples;
(4) Determination of methyltrimethoxysilane samples: and (3) taking a sample to be detected in a 25mL volumetric flask, adding a certain amount of urea into the volumetric flask, adjusting the pH of the solution to be within a range of 6-7, adding an internal standard substance standard solution, uniformly shaking the solution to a constant volume by using a solvent, and performing headspace gas chromatography detection under the chromatography condition in the step (3) to obtain the peak area, and obtaining the methyltrimethoxysilane content according to the drawn standard curve.
In the methyltrimethoxysilane synthesis process, byproducts such as hydrogen chloride, methyldimethoxychlorosilane and the like are inevitably generated, and solvents such as dimethylbenzene and the like are introduced. Although the content of methyltrimethoxysilane in the product can be detected by using a gas chromatography normalization method, after a sample enters a chromatographic column, the separation effect of materials such as methyltrimethoxysilane, dimethylbenzene and the like and methyltrimethoxysilane is poor, the service lives of the chromatographic column and an instrument are seriously reduced by hydrogen chloride, and meanwhile, the difference of response factors of the byproducts in the chromatographic column is large, so that the detection result is greatly influenced. The external standard method can also achieve the aim of accurately detecting the content of the methyltrimethoxysilane, but in the method, the methyltrimethoxysilane is easy to absorb moisture, and pure materials of the methyltrimethoxysilane cannot be obtained to prepare standard liquid. Urea is dissolved in solvents such as methanol, if the neutralized sample is directly injected into a gas chromatograph, the neutralized sample can be left in the chromatographic column, and the service life of the chromatographic column can be seriously influenced for a long time, so the invention adopts an internal standard method, and simultaneously uses a headspace injector for sample injection to determine the content of methyltrimethoxysilane in the methyltrimethoxysilane synthesis process.
For a more detailed explanation of the present invention, the present invention will now be described in further detail with reference to the following examples. Specific examples are as follows:
example 1
The existing batch of methyltrimethoxysilane crude products produced by an alcoholysis method has the content of about 50 percent (impurities comprise methanol, dimethyldimethoxysilane and the like), and the content of methyltrimethoxysilane needs to be measured, and the specific steps are as follows:
a method for detecting the content of methyltrimethoxysilane in methyltrimethoxysilane synthesis by using an internal standard method of headspace sampler sample injection comprises the following specific steps:
(1) Preparing a methyltrimethoxysilane standard solution: firstly, adding a certain amount of absolute ethyl alcohol into a 25mL volumetric flask, then accurately weighing 1g of methyltrimethoxysilane in the volumetric flask, fixing the volume to a scale mark by using the absolute ethyl alcohol, and shaking uniformly;
(2) Preparing an internal standard solution: accurately weighing 1g of methyltriethoxysilane in a 25mL volumetric flask, and uniformly shaking by using absolute ethyl alcohol to fix the volume to a scale mark;
(3) Drawing a standard curve: and respectively weighing 0.1mL, 0.5mL, 1mL, 2mL and 5mL of the methyltrimethoxysilane standard solution, respectively mixing with 1mL of the internal standard solution in 5 25mL volumetric flasks, and fixing the volume to a scale mark by using absolute ethyl alcohol to obtain a standard curve solution. Performing gas chromatograph detection on the prepared solution by adopting headspace sample injection to obtain corresponding peak areas, and drawing a standard curve according to the peak areas of the contents of the samples; drawing and solving a linear regression equation: y=0.5326x+0.0013, correlation coefficient R 2 =1；
(4) Determination of methyltrimethoxysilane samples: and (3) taking 1g of a sample to be detected in a 25mL volumetric flask, adding 0.6g of urea to adjust the pH value to 6.8, adding 1mL of an internal standard solution, fixing the volume by using absolute ethyl alcohol, detecting by means of chromatographic conditions in the step (3), obtaining the peak area of methyltrimethoxysilane in the sample to be detected, calculating according to a standard curve in the step (3), obtaining the content of methyltrimethoxysilane in the sample to be detected, and taking the average value of three detection results to obtain the final content of 49.13%.
Example 2
The existing batch of crude methyltrimethoxysilane products produced by a batch method has the content of about 75 percent (impurities comprise methanol, dimethyldimethoxysilane and the like), and the content of the methyltrimethoxysilane needs to be measured, and the method comprises the following specific steps:
a method for detecting the content of methyltrimethoxysilane in methyltrimethoxysilane synthesis by using an internal standard method of headspace sampler sample injection comprises the following specific steps:
(1) Preparing a methyltrimethoxysilane standard solution: firstly, adding a certain amount of absolute ethyl alcohol into a 25mL volumetric flask, then accurately weighing 1g of methyltrimethoxysilane in the volumetric flask, fixing the volume to a scale mark by using the absolute ethyl alcohol, and shaking uniformly;
(2) Preparing an internal standard solution: accurately weighing 1g of methyltriethoxysilane in a 25mL volumetric flask, and uniformly shaking by using absolute ethyl alcohol to fix the volume to a scale mark;
(3) Drawing a standard curve: the methyltrimethoxysilane standard solution is respectively weighed
Mixing 0.1mL, 0.5mL, 1mL, 2mL and 5mL with 1mL internal standard substance standard solution respectively, putting into 5 25mL volumetric flasks, and fixing the volume to scale marks by using absolute ethyl alcohol to obtain standard curve solution. Performing gas chromatograph detection on the prepared solution by adopting headspace sample injection to obtain corresponding peak areas, and drawing a standard curve according to the peak areas of the contents of the samples; and solving a linear regression equation: y=0.5426x+0.0029, correlation coefficient R 2 =0.9999；
(4) Determination of methyltrimethoxysilane samples: and (3) taking 1g of a sample to be detected in a 25mL volumetric flask, adding 0.82g of urea to adjust the pH value to 6.6, adding 1mL of an internal standard solution, fixing the volume by using absolute ethyl alcohol, detecting by means of chromatographic conditions in the step (3), obtaining the peak area of methyltrimethoxysilane in the sample to be detected, calculating according to a standard curve in the step (3), obtaining the content of methyltrimethoxysilane in the sample to be detected, and taking the average value of three detection results to obtain the final content of 75.08%.
Example 3
The existing batch of methyltrimethoxysilane rectification products produced by a batch method has the content of about 99 percent (impurities comprise cross-linked matters and the like), and the content of methyltrimethoxysilane needs to be measured, which comprises the following specific steps:
a method for detecting the content of methyltrimethoxysilane in methyltrimethoxysilane synthesis by using an internal standard method of headspace sampler sample injection comprises the following specific steps:
(1) Preparing a methyltrimethoxysilane standard solution: firstly, adding a certain amount of normal hexane into a 25mL volumetric flask, then accurately weighing 1g of methyltrimethoxysilane into the volumetric flask,
the normal hexane is used for fixing the volume to the scale mark, and the shaking is uniform;
(2) Preparing an internal standard solution: accurately weighing 1g of methyltriethoxysilane in a 25mL volumetric flask, fixing the volume to a scale mark by using n-hexane, and shaking uniformly;
(3) Drawing a standard curve: and respectively weighing 0.1mL, 0.5mL, 1mL, 2mL and 5mL of the methyltrimethoxysilane standard solution, respectively mixing with 1mL of the internal standard solution in 5 25mL volumetric flasks, and fixing the volume to a scale mark by using n-hexane to obtain a standard curve solution. Performing gas chromatograph detection on the prepared solution by adopting headspace sample injection to obtain corresponding peak areas, and drawing a standard curve according to the peak areas of the contents of the samples; drawing and solving a linear regression equation: y= 0.5101x-0.0070, correlation coefficient R 2 =0.9991；
(4) Determination of methyltrimethoxysilane samples: and (3) taking 1g of a sample to be detected in a 25mL volumetric flask, adding 0.13g of urea to adjust the pH value to 7.0, adding 1mL of an internal standard solution, fixing the volume by using n-hexane, detecting by means of chromatographic conditions in the step (3), obtaining the peak area of methyltrimethoxysilane in the sample to be detected, calculating according to a standard curve in the step (3), obtaining the content of methyltrimethoxysilane in the sample to be detected, and taking the average value of three detection results to obtain the final content of 99.48%.
Label adding recovery experiment
In order to verify that the addition of urea in the invention does not affect the sample result, 2.5g of methyltrimethoxysilane sample A (the content of which is 99.84%) is accurately weighed in a 50mL volumetric flask, 1g of methyltriethoxysilane is added, 0.2g of urea is added, the volumetric flask is fixed to a scale mark by absolute ethyl alcohol, the urea is uniformly shaken until no urea solid is seen, 5mL of prepared solution is respectively removed from 5 25mL volumetric flasks, then 0.2g, 0.4g, 0.6g, 0.8g and 1.0g of sample A are respectively added into each volumetric flask, the volumetric flask is fixed to the scale mark by absolute ethyl alcohol, and the samples are respectively numbered 1, 2, 3, 4 and 5. After the mixture is uniform, a liquid-transferring gun is used for accurately transferring 0.5mL of sample into a headspace bottle, gas chromatography is carried out by adopting a headspace sample injection mode to detect, the peak area of methyltrimethoxysilane in the sample is recorded, and the recovery rate is calculated.
TABLE 1 recovery rate by adding standard
From the data, the recovery rate of the sample is stabilized within the range of 99% -104%, and the accuracy requirement can be met, so that the invention can be used as a detection method for detecting methyltrimethoxysilane.
Comparative experiments
To verify the effect of the pretreatment of the present invention, two methyltrimethoxysilane samples of example 1 were taken and each of them was designated C, D, sample C was treated as in example 1, and sample D was not treated. The two samples were each tested according to the chromatographic conditions of step (3) of example 1 for a total of 5 times, the peak areas of methyltrimethoxysilane in the samples were recorded, and the contents were calculated, and the results are shown in Table 2.
Table 2 comparative experiments
As shown by the data, the RSD of the treated sample is less than or equal to 0.05%, the sample test result is quite stable, the untreated sample result has larger fluctuation, the precision is poorer, and more reliable sample result data cannot be provided, so that the detection method for detecting the methyltrimethoxysilane is more accurate.
The experiment shows that the method for detecting the content of the methyltrimethoxysilane in the methyltrimethoxysilane synthesis by using the internal standard method of headspace sampler sample injection is feasible, and has high precision, accuracy and repeatability; meanwhile, hydrogen chloride in the sample is removed in the pretreatment process of the sample, so that the detection accuracy is improved, the service lives of instruments and chromatographic columns are prolonged, new impurities are not introduced, the content accuracy of the sample is greatly improved, and great convenience is brought to the subsequent neutralization process. Therefore, the method of the invention provides a more accurate method for measuring the content of the crude product of the methyltrimethoxysilane in the methyltrimethoxysilane synthesis process.
Claims (3)
1. The method for detecting the content of methyltrimethoxysilane by an internal standard method is characterized by comprising the following steps of: the method comprises the following steps:
(1) Preparing a methyltrimethoxysilane standard solution: firstly adding a certain amount of solvent into a 25mL volumetric flask, then accurately weighing a certain amount of methyltrimethoxysilane in the volumetric flask, fixing the volume to a scale mark by using the solvent, and shaking uniformly, wherein the solvent is any one of absolute ethyl alcohol, n-hexane or n-heptane;
(2) Preparing an internal standard solution: accurately weighing a certain amount of internal standard substance in a 25mL volumetric flask, fixing the volume to a scale mark by using a solvent, and shaking uniformly, wherein the internal standard substance is any one or more of methyltriethoxysilane, propyltriethoxysilane or dimethyldiethoxysilane;
(3) Drawing a standard curve: respectively weighing the methyltrimethoxysilane standard solution and the internal standard solution, mixing the methyltrimethoxysilane standard solution and the internal standard solution in a 25mL volumetric flask, fixing the volume to a scale mark by using a solvent to obtain standard curve solutions, preparing at least more than 5 standard curve solutions, detecting the prepared solutions by using a headspace sample gas chromatograph to obtain corresponding peak areas, and drawing a standard curve according to the peak areas of the contents of the samples;
(4) Determination of methyltrimethoxysilane samples: taking a sample to be detected in a 25mL volumetric flask, adding a certain amount of neutralizing agent urea into the volumetric flask, adjusting the pH of the solution to be within a range of 6-7, adding an internal standard substance standard solution, uniformly shaking the solution to a constant volume by using a solvent, performing headspace gas chromatography detection under the chromatography condition in the step (3) to obtain the peak area, obtaining the methyltrimethoxysilane content according to a drawn standard curve,
the detection conditions of the headspace gas chromatography are as follows: the initial temperature of the headspace sampler is 35 ℃, the heating rate is 10 ℃/min, the temperature is raised to 110 ℃, and the headspace sampler is kept for 10min; the nitrogen flow rate of the gas chromatograph is 1.5mL/min, the hydrogen flow rate is 30mL/min, the air flow rate is 400mL/min, and the column box adopts a temperature programming mode: maintaining for 2min in an initial environment at 50 ℃ with the temperature rising rate of: heating to 180 ℃ at 20 ℃/min, and keeping for 10min; sample injection amount is 0.4 mu L, a split flow mode is adopted, and the separation ratio is 50:1, the temperature of the sample inlet is 250 ℃, and the temperature of the detector is 260 ℃.
2. The method according to claim 1, characterized in that: the concentration of the internal standard substance is 0.5-1 g/L.
3. The method according to claim 1, characterized in that: the correlation coefficient R in the linear regression equation of the standard curve in the step (3) 2 ≥0.999。
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