CN105301031A - Method for determining hydrogen-containing silicone oil residual quantity in trisiloxane surfactant by one-dimensional hydrogen nuclear magnetic resonance method - Google Patents

Abstract

The invention discloses a method for determining the residual amount of hydrogen-containing silicone oil in a trisiloxane surfactant, which comprises the following steps: adopting a one-dimensional nuclear magnetic resonance spectrum, taking single-peak 1,3,5-tribromobenzene as a unified The internal standard is used for quantitative analysis or concentration determination of the trisiloxane surfactant, and the single-peak internal standard is used as the medium for one-dimensional NMR quantification for quantitative analysis. The method can not only be used for the determination of the hydrogen content of methyl hydrogen-containing silicone oil and block hydrogen-containing silicone oil, but also can be applied to the determination of the content of hydrogen-containing silicone oil in trisiloxane surfactants. The concentration of each monomer compound can be directly calculated according to the proportional relationship between the integral of the characteristic NMR signal of the compound in the sample and its concentration. The method solves the problems of inaccurate determination and cumbersome testing caused by signal overlap of trisiloxane surfactants, and the experimental scheme of the invention also has the possibility of accurately quantifying multiple compounds in the mixture.

Description

Method for Determination of Hydrogen-containing Silicone Oil Residue in Trisiloxane Surfactant by One-dimensional Proton Nuclear Magnetic Resonance Spectroscopy

technical field

The invention belongs to the field of chemical instrument analysis methods, and in particular relates to the determination of the residual amount of hydrogen-containing silicone oil in trisiloxane surfactants by a one-dimensional hydrogen nuclear magnetic resonance spectrum method.

Background technique

NMR technology has become an essential tool in the qualitative research of compounds because it can provide the most detailed, true and reliable chemical structure information. With the development of nuclear magnetic resonance technology, one-dimensional nuclear magnetic resonance is often used in quantitative analysis because it has many unique advantages:

For a defined nucleus, the signal intensity is proportional to the number of nuclei producing the signal and has nothing to do with the chemical nature of the nucleus. When using the internal standard method or relative measurement method to analyze a certain compound in the mixture, it is not necessary to use the pure product of the compound as a reference standard. The width of the NMR signal peak is very narrow, which is much smaller than the difference in chemical shift between the signals, so there is less obvious overlap between the signals of different components in the mixture. The NMR test experiment is simple and does not destroy the tested sample.

The main components of the trisiloxane surfactant are 1,1,1,3,5,5,5-heptamethyltrisiloxane (MD ^H M, belonging to hydrogen-containing silicone oil) and different allyl A series of mixtures of polyethers (different numbers of EO and PO segments, and different end-capping groups, such as methyl, acetyl and hydroxyl, etc.) obtained by hydrosilylation. The residual hydrogen-containing silicone oil in the trisiloxane surfactant will have an adverse effect on the packaging of the product, that is, the residue of the hydrogen-containing silicone oil will cause hydrogen to be generated in the product, which is not conducive to the packaging of the product. Therefore, by formulating corresponding standards, products that meet the corresponding indicators can be used for packaging, so as to better guide the production of trisiloxane surfactants.

The residual amount of silicone oil in the trisiloxane surfactant can be expressed by the index of hydrogen content. The lower the hydrogen content, the less the residual amount of hydrogen-containing silicone oil.

There have been reports on the determination of the hydrogen content of a certain hydrogen-containing silicone oil raw material before, and the main test methods include chemical method, infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy. Among them, the chemical titration method is often used as the benchmark for establishing a method for determining the hydrogen content of various hydrogen-containing silicone oils. Although there are reports on the determination of the hydrogen content of silicone oil raw materials by the NMR internal standard method, there is no report on the determination of the hydrogen-containing silicone oil residue in the mixture system by the NMR internal standard method-that is, the determination of the surface activity of trisiloxane by the NMR internal standard method The method for the residual amount of hydrogen-containing silicone oil in the agent has not been reported yet.

Contents of the invention

The purpose of the invention is to overcome the deficiencies in the prior art, to provide a simple, fast one-dimensional hydrogen nuclear magnetic resonance spectrum method to measure the residual amount of hydrogen-containing silicone oil in the trisiloxane surfactant, to solve the problem caused by the signal in the conventional hydrogen spectrum Overlap affects the accurate quantification of a compound and the problem of cumbersome testing. The purpose of solving this quantitative problem is to better guide the production of trisiloxane surfactants, so that the obtained trisiloxane surfactant products are less likely to produce air bubbles after packaging, thereby avoiding the possibility of cracking after packaging.

In order to achieve the above object, the present invention adopts the following technical solutions:

The invention provides a method for determining the residual amount of hydrogen-containing silicone oil in a trisiloxane surfactant by one-dimensional hydrogen nuclear magnetic resonance spectroscopy. The key to this method is to select a suitable internal standard substance, so as to avoid the problem of inability to quantify due to the overlapping of corresponding quantitative peaks, so that the internal standard substance can play a role as a bridge in the quantification, and can be converted with the quantified substance And get the specific content of the substance to be tested.

A method for determining the residual amount of hydrogen-containing silicone oil in a trisiloxane surfactant, comprising the steps of: adopting one-dimensional hydrogen nuclear magnetic resonance spectrum, using unimodal 1,3,5-tribromobenzene as a unified internal standard, to The trisiloxane surfactant is used for quantitative analysis or concentration determination, and the single-peak internal standard is used as a medium for one-dimensional NMR quantification for quantitative analysis.

Preferably, in the above determination method, one-dimensional hydrogen nuclear magnetic resonance spectroscopy is used as a quantitative method, and the internal standard is used as a bridge to measure the hydrogen content of methyl hydrogen-containing silicone oil or block hydrogen-containing silicone oil.

Preferably, in the above determination method, one-dimensional hydrogen nuclear magnetic resonance spectroscopy is used as a quantitative method, and the internal standard is used as a bridge to quantify the residual amount of hydrogen-containing silicone oil in trisiloxane surfactants with different molecular weights or different structures.

The application of the one-dimensional nuclear magnetic resonance method in the determination of the compound concentration in the mixture sample, due to the determination of the relative concentration ratio of some compounds in the mixture, when calculating the result of the relative concentration ratio, has nothing to do with the concentration of the internal standard itself, and can accurately determine each The concentration or relative proportion of the monomeric compounds. The present invention measures the content of a certain specific compound in the mixture, adopts a one-dimensional nuclear magnetic resonance hydrogen spectrum quantitative analysis method, and measures the compound to be quantified through a suitable internal standard.

Compared with the prior art, the present invention has the following beneficial effects:

1. Simple sample preparation: One of the key elements of this method is the use of a solid-containing unimodal compound as a single universal quantitative internal standard. Using a single internal standard, just mix to prepare the NMR sample to be tested. The sample of the mixture to be tested is dissolved and mixed evenly with the mother solution of the internal standard standard concentration, and then the nuclear magnetic resonance experiment can be directly carried out.

2. The measurement experiment time is relatively short: the test time (5-10 min) using a single internal standard NMR sample is less than the determination time (40 min) of the chemical titration method.

This method can be used not only for the determination of the hydrogen content of methyl hydrogen-containing silicone oil and block hydrogen-containing silicone oil, but also for the determination of the content of hydrogen-containing silicone oil in trisiloxane surfactants, while the general method can only be used for Determination of the hydrogen content of methyl hydrogen silicone oil or block hydrogen silicone oil. The concentration of each monomer compound can be directly calculated according to the proportional relationship between the integral of the characteristic NMR signal of the compound in the sample and its concentration. The method solves the problems of inaccurate determination and cumbersome testing caused by signal overlap of trisiloxane surfactants, and the experimental scheme of the invention also has the possibility of accurately quantifying multiple compounds in the mixture. If only the relative concentration ratio among the compounds is concerned, the obtained results are not affected by the concentration of the general internal standard by adopting the experimental scheme of the invention.

Description of drawings

Figure 1 is the one-dimensional proton nuclear magnetic resonance spectrum of MD ^H M and the internal standard. The Si-H proton peak of MD ^H M is selected as the basis for quantification, and its chemical shift is about 4.6ppm. The chemical shift of the internal standard is about 7.6ppm, and this chemical shift is used as the quantitative peak. Fig. 1 is also an illustration of the hydrogen content of MD ^H M measured by the internal standard method.

Figure 2 is a standard curve diagram of MD ^H M and the internal standard. The correlation coefficient obtained by quantification is 0.99976, indicating that the internal standard used can accurately quantify the content of hydrogen-containing silicone oil. In order to further test the quantitative method of H NMR spectroscopy, we used the chemical method to measure the hydrogen content of MD ^H M, and the hydrogen content of the hydrogen-containing silicone oil was determined by the chemical method as the standard.

Fig. 3 is a one-dimensional hydrogen nuclear magnetic resonance spectrogram of measuring the content of MD ^H M in the trisiloxane surfactant with an average molecular weight of about 612 in Example 2.

Fig. 4 is a one-dimensional hydrogen nuclear magnetic resonance spectrogram of measuring the content of MD ^H M in the trisiloxane surfactant with a molecular weight of about 674 in Example 3.

Fig. 5 is a one-dimensional hydrogen nuclear magnetic resonance spectrogram of measuring the content of MD ^H M in the trisiloxane surfactant with a molecular weight of about 807 in Example 4.

detailed description

The substantive content of the present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited thereto.

1. NMR experiment:

The nuclear magnetic resonance test experiment of the embodiment of the present invention and pattern processing and data analysis are carried out by the following methods:

NMR test experiments: all the NMR experiments involved in the invention are carried out at 25°C (298K) on a BrukerAVANCE400 NMR spectrometer. One-dimensional proton nuclear magnetic resonance experiment adopts Bruker standard pulse sequence as "zg30".

In order to ensure the accuracy of peak area integration, it is necessary to consider the optimization of parameters such as the number of conversion points SI, the spectral width SW, the number of scans NS, the waiting time D1, and the sampling time AQ.

The number of conversion points must be an even power of 2. If you need to input the number of conversion points such as 2K, 32K, in the NMR quantitative experiment, only when there are 5 description points on the half-width of the resonance peak, can the quantitative accuracy be guaranteed .

After the number of Fourier transform points is determined, the digital resolution of the spectrogram is determined. Calculated as follows:

Formula 1

The spectral width SW is generally only related to the chemical shift of the sample. In the one-dimensional H NMR spectrum test of the present invention, the unified spectral width is SW=10ppm.

In the NMR test, it is necessary to excite the sample multiple times and collect the signal from the sample to improve the quality of the spectrum. The number of times to excite the sample and collect the signal of the sample is called the number of scans.

In the NMR quantitative experiment, there are literatures that prove that the signal-to-noise ratio S/N ≥ 150 must be ensured, so that the uncertainty of the quantitative results can be around 1%.

After exploring the conditions, it can be determined that the number of scans NS=32 can meet the quantitative requirements.

During the NMR test, the waiting time D1 has a greater impact on the quantification, and it is necessary to continue to try to determine D1.

For subsequent nuclear magnetic test experiments, it is enough to set D1=4s.

The sampling time AQ has an important influence on the accuracy of quantification. In the process of quantification, the free relaxation decay (FID) must be guaranteed completely, and it can be satisfied by setting AQ=4s.

Other parameters such as gain RG, number of empty scans DS, and test temperature TE have little effect on quantification, and the parameters can be set according to the instrument.

There are two reference principles for the selection of quantitative peaks: (1) high signal-to-noise ratio S/N, (2) independent resonance peaks without other interference peaks.

Referring to the above two principles, the proton peak of Si-H can be selected as the quantitative peak, and the Si-H chemical shift is about 4.6ppm; the internal standard is a single peak, and the single peak is selected as the quantitative peak, and the chemical shift is about 7.6ppm.

The peak area integration interval is also an important data processing step that affects quantification. In all processed data, the quantification intervals are 4.7-4.5 and 7.7-7.5, respectively.

2. Map processing and data analysis:

Before quantitative analysis, baseline correction and automatic phase adjustment were performed on the Fourier transformed spectra using MestReNova software.

In ¹ H-NMR, the area or height of the resonance peak is proportional to the number of protons that generate the resonance peak, which is the basis for quantification. which is:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \%</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}$

Formula 2

A _s : the integral area of the quantitative peak of the measured sample; n _s : the number of protons contained in the quantitative peak of the measured sample;

M _s : Molecular mass of the sample to be tested; A _r : Integrated area of the quantitative peak of the internal standard substance;

n _r : the number of protons contained in the quantitative peak of the internal standard substance; M _r : the molecular mass of the internal standard substance;

m _r : the mass of the internal standard; W _r : the purity of the internal standard; m _s : the mass of the sample;

Hydrogen content: the number of grams of Si-H bonds per 100g of silicone oil, expressed in H%.

The formula for determining the hydrogen content of hydrogen-containing silicone oil by the internal standard method of hydrogen nuclear magnetic resonance spectroscopy can be deduced from the definition of hydrogen content:

Formula 3

The _sample m is the quality of the sample, and the _inside m is the quality of the internal standard;

_Sample A is the integrated peak area of the sample, and A _is the peak area integrated by the internal standard;

The hydrogen content can reflect the residual amount of hydrogen-containing silicone oil in the trisiloxane surfactant. Therefore, the production of the trisiloxane surfactant can be guided by this test method.

Example 1:

Consistency analysis of one-dimensional proton nuclear magnetic resonance spectroscopy and chemical method for determination of hydrogen content in MD ^H M:

In order to verify the feasibility of using the one-dimensional hydrogen nuclear magnetic resonance spectrum internal standard method to measure the hydrogen content of hydrogen-containing silicone oil, the present invention uses chemical titration to measure the hydrogen content of hydrogen-containing silicone oil as a comparison, and also in the determination of other embodiments The chemical titration method was also used as a comparison.

Reagents used and sample preparation: MD ^H M with a purity of 99% was purchased from West Asia Reagent Company, and deuterated chloroform (CDCl ₃ ) with a purity of 99.9% was purchased from CIL (Cambridge Isotope Laboratories, Massachusetts, USA). Sodium thiosulfate (AR), potassium iodide (AR), soluble starch (AR) and concentrated sulfuric acid (AR) were purchased from Tianjin Damao Reagent Factory, potassium dichromate (PT) was purchased from Kemiou Reagent Company, 1 , 3,5-tribromobenzene (AR) was purchased from Aladdin Reagent Company. The weighing accuracy of the Mettler analytical balance used is ±0.1 mg.

Determination of hydrogen content in hydrogen-containing silicone oil by chemical method:

Weigh the sample in a 250mL iodine bottle, add 20mL carbon tetrachloride, 10mL Br ₂ -CH ₃ COOH with a molar concentration of about 0.2mol/L and 0.25mL deionized water respectively, plug the stopper of the iodine bottle, and liquid seal up. Shake well and place in the dark for 30 minutes. After the reaction was completed, 25 mL of KI solution with a mass fraction of 10% was added, and the mouth of the bottle was rinsed with deionized water. When the titration with the calibrated sodium thiosulfate solution approaches the end point, add 1 mL of starch indicator with a mass concentration of 10 g/L, and titrate until the blue color disappears.

The calculation of the hydrogen content of silicone oil by chemical method is shown in formula 4:

$\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; \%</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 1.008</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 3</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}\mathrm{<span\; class="notranslate">\; \%</span>}$

m is the mass/ _g of the sample, _c is the concentration/(mol/L) of the calibrated Na2S2O3 _;

V ₀ is the volume/mL of Na ₂ S ₂ O ₃ consumed by the blank, and V ₁ is the volume/mL of Na ₂ S ₂ O ₃ consumed by the sample;

Formula 4

After 3 parallel experiments, the average hydrogen content of MD ^H M was measured to be 0.440% (theoretical hydrogen content was 0.448%, which was actually not reached, the relative error was 1.78%, and the relative average deviation was 0.23%). as the true value of the hydrogen content of MD ^H M.

Preparation of 1,3,5-tribromobenzene (internal standard) standard solution: Weigh 0.0600g of 1,3,5-tribromobenzene into a 5mL volumetric flask, add deuterated chloroform and ultrasonically dissolve it, and dilute to 5mL after dissolution , the concentration is 12mg/mL. When preparing samples, use a pipette gun to pipette 0.25mL of the standard solution into an NMR tube each time, and then mix it with MD ^H M solution to 0.5mL.

Preparation of MD ^H M standard solution: Weigh 0.1600g MD ^H M into a 2mL volumetric flask, and dilute to volume with deuterated chloroform. Use a pipette gun to transfer 1mL to another volumetric flask, then dilute to 2mL with deuterated chloroform, repeat the above steps to obtain 80mg/mL, 40mg/mL, 20mg/mL, 10mg/mL, 5mg/mL, 2.5mg /mL of hydrogen-containing silicone oil solution. Pipette 0.25mL of the standard solution each time and mix it with the above-mentioned internal standard solution. The hydrogen content of the hydrogen-containing silicone oil was determined under the above-mentioned nuclear magnetic resonance test conditions.

The MD ^H M and internal standard peak areas in the mixture were obtained by using the nuclear magnetic software MestReNova. In the one-dimensional hydrogen nuclear magnetic resonance spectrum, the proton peak on the internal standard benzene ring and the Si-H proton peak of the MD ^H M were selected as quantitative peak. In Figure 1, the peak area integrals of the internal standard and sample quantitative peaks are 3.000 and 0.406, respectively. According to the known concentration of the internal standard, the hydrogen content of MD ^H M can be calculated as 0.430% according to formula 3. Through three parallel experiments, the hydrogen content was obtained to be 0.430%, 0.434% and 0.435%, respectively, the average value of the three parallel experiments was 0.433%, and the relative average deviation was 0.46%. The hydrogen content of MD ^H M was determined to be 0.440% based on multiple parallel determination experiments by chemical titration. Therefore, the relative error of the above three experiments is 1.59%. Six hydrogen-containing silicone oils and internal standard mixtures with different concentration gradients were measured according to the above-mentioned nuclear magnetic resonance test conditions, and a series of peak area ratios of one-dimensional hydrogen nuclear magnetic resonance spectra were obtained.

Plotting A _s /A _r against m _s /m _r , the standard curve is shown in Figure 2. The obtained equation is y=0.51612x-0.00095, and the correlation coefficient is 0.99974. The linear relationship and repeatability of the hydrogen content of hydrogen-containing silicone oil determined by nuclear magnetic resonance are very good, which shows the feasibility of one-dimensional hydrogen nuclear magnetic resonance spectroscopy to determine the hydrogen content of MD ^H M.

This method is also applicable to the determination of the hydrogen content of methyl hydrogen-containing silicone oil (Type A, MD ^H M is one of them) and block hydrogen-containing silicone oil (Type B).

Among them, methyl hydrogen-containing silicone oil and block hydrogen-containing silicone oil were purchased from Nanchang Tianrun New Material Co., Ltd.

Example 2:

Determination of residual MD ^H M content in trisiloxane surfactant with an average molecular weight of 612

In the actual storage and production process, MD ^H M will produce hydrogen after a period of time. Since the trisiloxane surfactant will remain MD ^H M during production, a certain amount of MD ^H M will cause the packaging bag to bulge or even rupture. Therefore, the detection of MD ^H M content in trisiloxane surfactant has an important guiding role in production.

When determining the content of hydrogen-containing silicone oil in trisiloxane surfactant, the residual amount of MD ^H M can be expressed by the hydrogen content.

Preparation of internal standard solution: Weigh 0.0600g of 1,3,5-tribromobenzene into a 5mL volumetric flask, add deuterated chloroform and ultrasonically dissolve, dilute to 5mL with deuterated chloroform, the concentration is 12mg/mL, pipette Take 0.25mL of the standard solution in an NMR tube, and mix it with trisiloxane surfactant solution to 0.5mL. The unused internal standard solution should be sealed and refrigerated for the next use.

Preparation of trisiloxane surfactant solution: Weigh 0.8000g of trisiloxane surfactant sample in a 2mL volumetric flask, dilute to 2mL with deuterated chloroform, pipette 0.25mL of the solution and mix with internal standard solution in Mix in an NMR tube and sonicate for 30s.

The test was carried out according to the above-mentioned NMR test conditions, and the one-dimensional hydrogen nuclear magnetic resonance spectrum and the integrated area were obtained, as shown in FIG. 3 , which is the one-dimensional hydrogen nuclear magnetic resonance spectrum of the trisiloxane surfactant. The result of three parallel determination peak areas is 1.475, 1.476, 1.476, can calculate and draw hydrogen content according to formula 3 and be 0.014%, 0.014% (0.0141%), 0.014% (0.0141%), average value is 0.014% (0.0141%) ), which is basically consistent with the result 0.014% (average value 0.0142%) measured by chemical titration. Bring the ratio of the above-mentioned peak area to the internal standard peak area into the standard curve equation y=0.51612x-0.00095, and then combine with formula 2 to obtain that every 100 mg trisiloxane sample contains 2.87 mg MD ^H M, which is converted into a hydrogen content that is basically the same as The results of the measurements were consistent.

Embodiment 3: Determination of the expansion of the hydrogen-containing silicone oil residual method in trisiloxane surfactants of different molecular weights

In order to further verify the feasibility of the method for determining the residual amount of hydrogen-containing silicone oil in trisiloxane surfactants, the present invention uses trisiloxane surfactant mixtures with different numbers of EO chain members as quantitative research objects. The preparation and pipetting of the internal standard solution were consistent with Example 2. The preparation and pipetting of the sample solution were consistent with Example 2.

Tested according to the above-mentioned NMR test conditions, a one-dimensional hydrogen nuclear magnetic resonance spectrum is obtained, as shown in Figure 4, which is the one-dimensional hydrogen nuclear magnetic resonance spectrum of a trisiloxane surfactant with an average molecular weight of 674. The results of three parallel determinations of the peak areas are 0.658, 0.654, 0.653, and the hydrogen content can be calculated according to formula 3 to be 0.006% (0.0063%), 0.006% (0.0062%), 0.006% (0.0062%), and the average value is 0.006 %, which is basically consistent with the result of 0.006% (0.0059%) determined by chemical titration. Bring the ratio of the above-mentioned peak area to the internal standard peak area into the standard curve equation y=0.51612x-0.00095, and then combine with formula 2 to obtain that every 100 mg trisiloxane sample contains 1.27 mg MD ^H M, which is converted into a hydrogen content that is basically the same as The results of the measurements were consistent.

Example 4:

Determination of the residual amount of hydrogen-containing silicone oil in the trisiloxane surfactant with an average molecular weight of 807 The preparation and pipetting of the internal standard solution are consistent with Example 2. The preparation and pipetting of the sample solution were consistent with Example 2.

Tested according to the above-mentioned NMR test conditions, a one-dimensional hydrogen nuclear magnetic resonance spectrum is obtained, as shown in FIG. 5 , which is a one-dimensional hydrogen nuclear magnetic resonance spectrum of a trisiloxane surfactant. The results of the three parallel determinations of the peak areas are 0.610, 0.612, and 0.614. According to the formula, the average value of the hydrogen content can be calculated to be 0.006% (0.0058%), 0.006% (0.0058%), and 0.006% (0.0059%). It is 0.006%, which is basically consistent with the result of 0.006% (0.0058%) determined by chemical titration. Bring the ratio of the above-mentioned peak area to the internal standard peak area into the standard curve equation y=0.51612x-0.00095, and then combine with formula 2 to obtain that every 100 mg trisiloxane sample contains 1.19 mg MD ^H M, which is converted into a hydrogen content that is basically the same as The results of the measurements were consistent.

The present invention is applicable to the detection of the residual amount of hydrogen-containing silicone oil in a series of trisiloxane surfactants. The chemical structure of the trisiloxane surfactants is shown in the following structural formula, that is, allyl polyether at the hydroxyl end, methyl Or acetyl-terminated allyl polyether and the trisiloxane surfactant obtained by reacting the three types of polyethers with different molecular weights and MD ^H M. This provides a relatively simple and fast test method for actual production.

5≤n≤20, 0≤m≤10, R=H, CH ₃ , CH ₃ CO.

Claims (3)

1. a kind of assay method of hydrogen-containing silicone oil residue in trisiloxane surfactant, it is characterized in that comprising the steps: adopt one-dimensional hydrogen nuclear magnetic resonance spectrum, take unimodal 1,3,5-tribromobenzene as Unified internal standard, quantitative analysis or concentration determination of trisiloxane surfactant, using single peak internal standard as one-dimensional nuclear magnetic resonance quantitative medium for quantitative analysis. 2. The method according to claim 1, characterized in that the use of one-dimensional hydrogen nuclear magnetic resonance spectrum is a quantitative method, and the internal standard is used as a bridge to measure the hydrogen content of methyl hydrogen-containing silicone oil or block hydrogen-containing silicone oil. 3. The method according to claim 1, wherein it is characterized in that using one-dimensional proton nuclear magnetic resonance spectrum is a quantitative method, and the internal standard is used as a bridge to quantify the amount of hydrogen-containing silicone oil in the trisiloxane surfactants of different molecular weights or different structures. residue.