CN115047119A - Method for detecting trace acetic anhydride in acetyl terminated polyether - Google Patents
Method for detecting trace acetic anhydride in acetyl terminated polyether Download PDFInfo
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- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 title claims abstract description 276
- 229920000570 polyether Polymers 0.000 title claims abstract description 69
- 239000004721 Polyphenylene oxide Substances 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title claims abstract description 31
- 125000000218 acetic acid group Chemical group C(C)(=O)* 0.000 title claims abstract description 29
- 239000000523 sample Substances 0.000 claims abstract description 77
- FZERHIULMFGESH-UHFFFAOYSA-N N-phenylacetamide Chemical compound CC(=O)NC1=CC=CC=C1 FZERHIULMFGESH-UHFFFAOYSA-N 0.000 claims abstract description 50
- 238000001212 derivatisation Methods 0.000 claims abstract description 33
- 229960001413 acetanilide Drugs 0.000 claims abstract description 25
- 238000006243 chemical reaction Methods 0.000 claims abstract description 18
- 239000007788 liquid Substances 0.000 claims abstract description 17
- 239000003153 chemical reaction reagent Substances 0.000 claims abstract description 15
- 239000012488 sample solution Substances 0.000 claims abstract description 15
- 239000012086 standard solution Substances 0.000 claims abstract description 15
- 239000000243 solution Substances 0.000 claims abstract description 12
- -1 aromatic primary amine compounds Chemical class 0.000 claims abstract description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical group OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 33
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N N-phenyl amine Natural products NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims description 31
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical group C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 22
- 238000001514 detection method Methods 0.000 claims description 13
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 238000004458 analytical method Methods 0.000 claims description 9
- 239000012071 phase Substances 0.000 claims description 5
- 239000011259 mixed solution Substances 0.000 claims description 4
- 238000004811 liquid chromatography Methods 0.000 claims description 2
- 238000011068 loading method Methods 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims description 2
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims 6
- 239000002904 solvent Substances 0.000 claims 2
- 125000002490 anilino group Chemical group [H]N(*)C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 claims 1
- 239000000010 aprotic solvent Substances 0.000 claims 1
- 239000008367 deionised water Substances 0.000 claims 1
- 229910021641 deionized water Inorganic materials 0.000 claims 1
- 239000012074 organic phase Substances 0.000 claims 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 32
- 229960000583 acetic acid Drugs 0.000 description 11
- 238000005303 weighing Methods 0.000 description 10
- 238000002347 injection Methods 0.000 description 9
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- 230000014759 maintenance of location Effects 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- NEAQRZUHTPSBBM-UHFFFAOYSA-N 2-hydroxy-3,3-dimethyl-7-nitro-4h-isoquinolin-1-one Chemical compound C1=C([N+]([O-])=O)C=C2C(=O)N(O)C(C)(C)CC2=C1 NEAQRZUHTPSBBM-UHFFFAOYSA-N 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 230000000875 corresponding effect Effects 0.000 description 3
- 238000004128 high performance liquid chromatography Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- BSWWXRFVMJHFBN-UHFFFAOYSA-N 2,4,6-tribromophenol Chemical compound OC1=C(Br)C=C(Br)C=C1Br BSWWXRFVMJHFBN-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- XXROGKLTLUQVRX-UHFFFAOYSA-N allyl alcohol Chemical compound OCC=C XXROGKLTLUQVRX-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 238000001819 mass spectrum Methods 0.000 description 2
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- 239000012528 membrane Substances 0.000 description 2
- 150000002989 phenols Chemical class 0.000 description 2
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- XDPCNPCKDGQBAN-BYPYZUCNSA-N (3s)-oxolan-3-ol Chemical compound O[C@H]1CCOC1 XDPCNPCKDGQBAN-BYPYZUCNSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- WTDHULULXKLSOZ-UHFFFAOYSA-N Hydroxylamine hydrochloride Chemical compound Cl.ON WTDHULULXKLSOZ-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000008061 acetanilides Chemical class 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000011088 calibration curve Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004737 colorimetric analysis Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010812 external standard method Methods 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000012362 glacial acetic acid Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 150000004698 iron complex Chemical class 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000005464 sample preparation method Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 229920002545 silicone oil Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000009210 therapy by ultrasound Methods 0.000 description 1
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- 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
- G01N30/06—Preparation
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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
- G01N30/62—Detectors specially adapted therefor
- G01N30/74—Optical detectors
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Abstract
A method for detecting trace acetic anhydride in acetyl terminated polyether comprises the following steps: firstly, preparing a sample solution and adding acetic anhydride standard solutions with different proportions; derivatization treatment: respectively adding sufficient derivatization reagents into the sample solutions containing the acetic anhydride with different concentrations obtained in the step I to be loaded, wherein the derivatization reagents are aromatic primary amine compounds; detecting and analyzing: setting liquid chromatogram conditions, respectively separating the derived solutions of the samples added with external standards with different concentrations obtained in the step (II) through liquid chromatogram, detecting through an ultraviolet detector, drawing a standard curve for the peak area of the acetanilide generated after the reaction is carried out for the same time and the corresponding concentration of the added acetic anhydride, and calculating the content of the acetic anhydride in the polyether sample to be detected according to the standard curve. The method can accurately detect the actual content of trace acetic anhydride in the acetyl terminated polyether sample.
Description
Technical Field
The invention relates to the technical field of trace impurity detection, in particular to a method for detecting trace acetic anhydride in acetyl terminated polyether.
Background
Acetyl terminated polyether refers to polyether in which the hydrogen on the terminal hydroxyl group of the polyether is replaced by acetyl. The synthesis of soft foam homogenizing agents in the polyurethane industry generally requires the use of high molecular weight allyl-terminated polyethers, wherein acetyl termination is a commonly used termination means in the production of such polyethers. Residual acetic anhydride in the polyether after the end capping is removed by adding water for hydrolysis and then degassing. If the post-treatment fails to control the acetic anhydride content effectively, the residual acetic anhydride content exceeding 0.001% will largely affect the catalyst activity in the silicone oil grafting reaction with the allyl alcohol polyether. But the equivalent amount of acetic acid in the polyether does not have much influence on the reactivity. Therefore, the active quality of the capped polyether cannot be fully guaranteed by determining the content of the back-pushed acetic anhydride by the acid value. Therefore, the content of acetic anhydride in the capped polyether is really identified to have higher practicability.
However, analysis of the content of trace acetic anhydride in the capped polyether is only reported, and the method for detecting acetic anhydride in acetic acid is mainly described in the chemical reagent standard compilation GB/T676-2007, and the method is based on the fact that acetic anhydride reacts with hydroxylamine chloride under anhydrous condition to generate hydroxamic acid, the hydroxamic acid reacts with iron under acidic condition to generate red hydroxamic acid iron complex, and finally, the detection result is obtained by the method of comparing the color with a standard solution. The detection lower limit of the method for the content of the acetic anhydride is 0.01 percent, and obviously, the method cannot meet the requirement of the content test of the acetic anhydride which can influence the activity of the polyether. CN201810547929.4 changes the adding sequence and adding amount of reagent on the basis of GB/T676-2007 standard, optimizes the detection lower limit and detection sensitivity of the method, but compared with the instrumental analysis, the colorimetric method can only compare with the acetic anhydride color development condition of the standard solution (higher or lower than the acetic anhydride concentration of the standard solution), and can not accurately determine the specific content of the acetic anhydride in the sample.
On the other hand, acetic anhydride itself is widely used as a common derivatization reagent for qualitative and quantitative analysis of high-boiling-point hydroxyl compounds. CN200910142877.3 discloses a test method for quantitatively analyzing 2,4, 6-tribromophenol in seawater and fresh water by derivatization with acetic anhydride and using a gas chromatograph ECD detector. CN201010567280.6 discloses a method for rapidly detecting phenolic compounds in liquid by an online derivatization membrane sample mass spectrum, which adopts the membrane sample mass spectrum and an online acetic anhydride derivatization device to realize rapid detection of phenolic compounds in liquid samples. CN201910850662.0 discloses a method for quantitatively analyzing the content of an enantiomer of (S) - (+) -3-hydroxytetrahydrofuran by using acetic anhydride as a derivatization reagent and using a CP-Chirasil Dex CB chromatographic column through gas chromatography. Therefore, the acetic anhydride has the characteristics of high reaction activity and easy derivatization, and provides possibility for quantitative analysis of the acetic anhydride with extremely low content.
Disclosure of Invention
In order to overcome the defects of the existing technology for analyzing the content of trace acetic anhydride in polyether, the invention aims to provide a method for detecting trace acetic anhydride in acetyl-terminated polyether, which combines the characteristic of easy derivatization of acetic anhydride, is easy to operate and has accurate detection result.
To achieve the object of the present invention, the following background experiment was carried out to confirm that acetic acid does not participate in derivatization, and that acetic anhydride derivatization is continuously carried out.
1. Instruments and reagents
The liquid chromatograph model is as follows: agilent 1200 quaternary gradient series and matched DAD detector and constant temperature chromatographic column system;
the methanol and the tetrahydrofuran are HPLC grade chromatographic purities;
the purity of acetic anhydride, aniline and acetanilide is not less than 99% (Sigma-Aldrich);
2. sample configuration
Accurately weighing 0.0300g of aniline in a 10ml volumetric flask, adding tetrahydrofuran, fixing the volume and shaking up;
3. sample pretreatment
Derivatization: respectively weighing 0.9625g of polyether (2), (1) 0.9535g of polyether (3), (0.9995 g of polyether) and (4)0.0519g of glacial acetic acid into four 10mL volumetric flasks, respectively adding 100 mu L of aniline solution (0.0030g/mL) prepared in advance, metering the volume by using tetrahydrofuran, shaking up, standing, and reacting for 30 minutes to obtain a primary derivatized sample solution;
4. measurement method
Starting each unit and a chromatographic workstation of a computer and an instrument according to standard operation rules of the instrument, setting instrument conditions, carrying out sample injection analysis on the prepared sample solution after the chromatographic column is well balanced and the background signal of the instrument is stable, and confirming components according to the retention time of each peak. The program sets continuous automatic sample injection at half an hour intervals, and the sample injection amount is 20 mu L each time. The samples were sequentially injected at 30min intervals in the order of the labels in FIG. 1 for analysis. Each sample was analyzed four times, with reaction time correlated to sample sequence and sample wait time.
As shown in FIG. 1, aniline peaks at a retention time of around 15.5min, and acetanilide peaks at a retention time of around 17.5 min. As the reaction time increases, traces of acetic anhydride in the polyether will react with the excess aniline and the acetanilide produced will increase linearly over a certain time span (at least 8h) (FIGS. 1-1, 1-2 and 1-3 correspond to three parallel experiments). In addition, as can be seen from (1) to (4) in fig. 1, when 0.05g of acetic acid, which is equivalent to 5% of the polyether equivalent of acetic acid (the residual acetic acid in the actual polyether is less than 100 ppm), is added, the amount of acetanilide formed is also quite limited and does not increase continuously with the increase of the reaction time, which indicates that the residual acetic acid in the polyether does not react with aniline under the reaction conditions, and ensures that the amount of acetanilide is only related to the content of acetic anhydride in the sample, thereby eliminating the interference of the residual acetic acid in the capped polyether.
The above background experiment shows that: derivatization of acetic anhydride continues and increases linearly during the waiting time for injection (at least 8 h). This is one of the conditions under which the process of the present invention can be successfully carried out.
The purpose of the invention is realized by the following technical scheme:
a method for detecting trace acetic anhydride in acetyl terminated polyether is characterized by comprising the following steps:
In some embodiments, the method for detecting trace acetic anhydride in the acetyl terminated polyether comprises the following steps:
preparation of standard acetic anhydride solution: weighing 0.020g +/-5 mg of acetic anhydride in a 25ml volumetric flask, adding tetrahydrofuran to a scale mark, fixing the volume, shaking up to be used as an external standard liquid, and calculating the mass fraction of the acetic anhydride in the external standard liquid;
preparation of aniline standard solution: weighing 0.030g +/-5 mg of aniline in a 10ml volumetric flask, adding tetrahydrofuran to a scale mark, fixing the volume and shaking up;
derivatization of the sample: weighing 1.0g of polyether sample to be tested, respectively placing the polyether sample to be tested in 5 10mL volumetric flasks, respectively transferring 0,5,10,20 and 50 mu L of acetic anhydride standard solution prepared by S1 into the 5 10mL volumetric flasks, adding about 5mL of tetrahydrofuran, shaking until the sample is completely dissolved, adding 100 mu L of aniline solution prepared by S2 after the sample is completely dissolved, fixing the volume, shaking uniformly, standing, and reacting for 30 minutes to obtain a primary derivatized sample solution;
starting units and a chromatographic workstation of a computer and an instrument according to a standard operation rule of a high performance liquid chromatograph, setting instrument conditions, and continuously and automatically injecting the preliminary derivatization sample solution prepared in S3 after a chromatographic column is well balanced and an instrument background signal is stable;
and establishing a standard curve of an external standard method according to the area of the acetanilide peak correspondingly generated by adding different contents of acetic anhydride, and converting according to the standard curve to obtain the content of the acetic anhydride in the sample to be detected.
Preferably, the weighing results in each of S1 and S2 are accurate to 0.0001 g.
Preferably, the test conditions of the liquid chromatograph in S4 are as follows: the liquid chromatograph model is as follows: agilent 1200 quaternary gradient series and matched DAD detector and constant temperature chromatographic column system; and (3) chromatographic column: agilent ZORBAX SB-C18, wherein the column size is 4.6X 250mm, 5 μm; column temperature: 40 ℃; flow rate: 1 mL/min; sample introduction amount: 20 mu L of the solution; and (3) sample introduction mode: automatic sample introduction; gradient of mobile phase: 0-3min, methanol/water 10/90; 3-5min, methanol/water conversion to 30/70; 5-25min, methanol/water conversion to 90/10; keeping 90/10 unchanged with methanol/water for 25-30 min; detector wavelength: 254 nm.
The invention has the beneficial effects that:
1. the sample preparation method is simple, the derivatization reaction condition is mild, the upper machine solution is easy to wash and has no residue, the purification effect is good, and the maintenance of the instrument in the use process is reduced;
2. the acetic acid does not react with aniline under the test conditions, so that the amount of acetanilide is only related to the content of acetic anhydride in the sample, and the interference of residual acetic acid in the terminated polyether is eliminated;
3. the high molecular weight acetyl terminated polyether has higher viscosity and boiling point, is not suitable for gas phase analysis, has longer retention time and has no obvious absorption signal under 254nm wavelength when being used for liquid phase analysis, and avoids matrix interference;
4. accurate result, good repeatability, high specificity and sensitivity of detection, detection limit of acetic anhydride in the capped polyether sample lower than 0.001%, and recovery rate of the added acetic anhydride between 91.25% and 103.2%.
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Drawings
FIG. 1 is a schematic diagram showing the progress of the acetanilide reaction in different time periods for the same sample, wherein the ordinate represents the response signal of a liquid phase ultraviolet detector at a wavelength of 254nm and the abscissa represents the retention time of liquid chromatography;
FIG. 2 is a schematic diagram of the calculation of the acetic anhydride content in a sample.
Detailed Description
In the following examples, a calibration curve of the standard addition method is prepared, and it is necessary to plot the amount of acetanilide produced (liquid phase peak area) against the concentration of the acetic anhydride standard substance added. Since derivatization with acetic anhydride is ongoing and increases linearly, it is necessary to ensure that the time of the derivatization reaction is consistent for each sample. Because each sample is injected and tested twice, the acetanilide production amount after the acetic anhydride with each concentration reacts for a certain time (such as 5.5 hours) can be obtained through calculation, and a standard curve is established according to the acetanilide production amount, and the concentration of the acetic anhydride contained in the original solution is calculated.
Example 1:
1. instruments and reagents
Liquid chromatograph model: agilent 1200 quaternary gradient series and matched DAD detector and constant temperature chromatographic column system;
the methanol and the tetrahydrofuran are HPLC grade chromatographic purity;
acetic anhydride, aniline and acetanilide, all with a purity of no less than 99% (Sigma-Aldrich);
2. sample configuration
(1) Accurately weighing 0.0220g of acetic anhydride in a 25ml volumetric flask, adding tetrahydrofuran, fixing the volume, and shaking up to obtain an external standard solution;
(2) accurately weighing 0.0302g of aniline in a 10ml volumetric flask, adding tetrahydrofuran, fixing the volume and shaking up;
3. sample pretreatment
Derivatization: accurately weighing 5 parts of 1g of polyether sample A to be detected respectively, accurately weighing the polyether sample A to 0.0001g, and placing the polyether sample A and the polyether sample A in 10mL volumetric flasks respectively; respectively transferring 0,5,10,20 and 50 mu L of acetic anhydride standard solution prepared in the step (1), adding about 5mL of tetrahydrofuran, shaking until the sample is completely dissolved, performing ultrasonic treatment if necessary, adding 100 mu L of aniline solution prepared in the step (2) after the sample is completely dissolved, performing constant volume, shaking up, standing, and obtaining a primary derivatization sample solution after reacting for 30 minutes;
4. measurement method
Starting the computer, all units of the instrument and the chromatographic workstation according to the standard operation rules of the instrument, setting the instrument conditions, carrying out sample injection analysis on the prepared sample solution after the base line is stable, and confirming the components according to the retention time of each peak. The program sets continuous automatic sample injection at half an hour intervals, and the sample injection amount is 20 mu L each time.
In this example, the derivatization reaction was performed with acetic anhydride in excess of aniline.
Based on the experimental conclusion of the supplementary experiment (see fig. 1), the minute amount of acetic anhydride in the polyether continuously reacts with the excess aniline, and the amount of acetanilide produced increases linearly over a certain time period (at least 8 h). The data of two injections of the same sample are plotted (marked as S1 and S6), and the acetanilide solubility (peak area) of the sample added with 0,5,10,20 and 50 mu L of acetic anhydride standard solution is respectively calculated when the sample reacts for 5.5h, so as to ensure that the reaction time of the samples added with acetic anhydride with different concentrations is consistent. For example, for sample 1, the area of the acetanilide peak at 0.5h was 6974(S1) and the area of the acetanilide peak at 3h was 19269(S6) with the addition of 0 μ L of acetic anhydride standard solution, and plotting these two points gives curve y of 4918t +4515, so that the area of the acetanilide peak after 5.5h of reaction of sample 1 was 4918 x 5.5+ 4515-31564.0. In the same manner, as shown in the data in Table 1, the peak areas of the corresponding acetanilides at 5.5 hours of reaction of sample 1, sample 2, sample 4 and sample 5 were 31564.0, 33016.8, 38228.6 and 50490.6, respectively.
TABLE 1 summary of data from the calculation of acetic anhydride content for the samples of example 1
Considering samples 1, 2,4 and 5 with the addition of 0,5, 20 and 50 μ L of standard solutions of acetic anhydride, respectively, at concentrations of 0.0220 ÷ 25 ═ 8.80E-4g/mL, the relative amounts of acetic anhydride added to the polyether are 0, 4.4, 17.6 and 44.0ppm, respectively (for example, sample 5, the amount of acetic anhydride added is 8.80E-4 × 50 × 1000 ÷ 1 ÷ 44.0 ppm). The corresponding part of the added acetic anhydride reacted over 5.5h to generate acetanilide peak areas of 0, 1443.3, 6633.0 and 18876.1 respectively (taking sample 5 added with 44.0ppm acetic anhydride as an example, the added acetanilide peak area is 40490.6-31564.0 ÷ 1.0002 × 1.0018 ═ 18876.1). Thus, plotting the increased acetanilide peak area against the added acetic anhydride resulted in a correlation between the acetic anhydride content of the sample and the acetanilide formation at 5.5h of reaction, i.e., y-432.72X-401.68 (see Table 1 and FIG. 2). Finally, the acetanilide peak area in sample 1 was substituted into the relational expression, and the acetic anhydride content of this sample was (31564.0+401.68) ÷ 432.72 ÷ 1.0002 ═ 73.86 ppm.
When the liquid chromatograph is used for measurement, the adopted chromatographic conditions are as follows: the liquid chromatograph model is as follows: agilent 1200 quaternary gradient series and matched DAD detector and constant temperature chromatographic column system; a chromatographic column: agilent ZORBAX SB-C18, wherein the column size is 4.6X 250mm, 5 μm; column temperature: 40 ℃; flow rate: 1 mL/min; sample injection amount: 20 mu L of the solution; and (3) sample introduction mode: automatic sample introduction; gradient of mobile phase: 0-3min, methanol/water 10/90; 3-5min, converting methanol/water to 30/70; 5-25min, methanol/water conversion to 90/10; keeping 90/10 unchanged with methanol/water for 25-30 min; detector wavelength: 254 nm.
The repeatability and the standard recovery rate experiment of the method of the invention are as follows:
adding 3 acetic anhydride standard solutions with different concentration levels into a blank polyether A sample, then respectively processing the sample by the method of '3 and sample pretreatment' in example 1, wherein each concentration is 5 in parallel, analyzing the sample by the high performance liquid chromatography condition of '4 and determination method' in example 1, calculating the recovery rate according to the addition amount and the determination value, and the result shows that the addition amount recovery rate is between 91.25 and 103.2 percent and the relative standard deviation is between 1.344 and 4.188 percent, which indicates that the recovery rate of the method is high and the repeatability is good, and the specific data are shown in Table 2:
table 2 acetic anhydride normalized recovery and relative standard deviation (n ═ 5) for acetyl terminated polyether sample a
Example 2:
polyether sample B was selected and the residual acetic anhydride content of the sample was determined as described in example 1.
Example 3:
polyether sample C was selected and the residual acetic anhydride content of the sample was determined as described in example 1.
Example 4:
polyether sample D was selected and the residual acetic anhydride content of the sample was determined as described in example 1.
Example 5:
polyether sample E was selected and the residual acetic anhydride content of the sample was determined as described in example 1.
Examples 1-5 measurement of residual acetic anhydride content in acetyl terminated polyethers are given in the following table:
TABLE 3 detection results of residual acetic anhydride content in different acetyl terminated polyethers
The above embodiments are only preferred embodiments of the present invention, and the scope of the present invention should not be limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are intended to be covered by the claims.
Claims (8)
1. A method for detecting trace acetic anhydride in acetyl terminated polyether is characterized by comprising the following steps:
step 1, preparing acetyl terminated polyether sample solution to be detected, dividing the acetyl terminated polyether sample solution into a plurality of parts, and respectively adding acetic anhydride standard solutions with different proportions into the acetyl terminated polyether sample solution to obtain a plurality of parts of mixed solution;
step 2, derivatization treatment: adding sufficient derivatization reagents into the multiple mixed solutions obtained in the step 1 respectively to be subjected to sample loading, wherein the derivatization reagents are aromatic primary amine compounds;
step 3, detection and analysis: setting liquid chromatogram conditions, respectively carrying out liquid chromatogram separation on the derived solutions of the samples added with the external standards with different concentrations obtained in the step 2, detecting by an ultraviolet detector, drawing a standard curve for the peak area of acetanilide generated after the reaction is carried out for the same time and the corresponding concentration of the added acetic anhydride, and calculating the content of the acetic anhydride in the polyether sample to be detected according to the standard curve.
2. The method for detecting trace acetic anhydride in acetyl-terminated polyether according to claim 1, wherein the acetyl-terminated polyether sample to be detected in the step 1 is acetyl-terminated polyether with any structure, wherein the molecular weight is 350 to 5000, and the EO proportion is 0-100%.
3. The method for detecting trace acetic anhydride in acetyl terminated polyether according to claim 2, wherein in the step 1, the multiple parts are five parts, and the addition ratios of the standard solution of acetic anhydride with different ratios are 0ppm, 5ppm, 10ppm, 20ppm and 50ppm respectively relative to the amount of the acetyl terminated polyether sample to be detected.
4. The method for detecting trace acetic anhydride in acetyl terminated polyether as claimed in claim 3, wherein the concentration of the derivatization reagent added in step 2 is 200-500ppm, the temperature of the derivatization reaction is 20-80 ℃, and the time of the derivatization reaction is 0.5 h.
5. The method for detecting trace acetic anhydride in acetyl terminated polyether according to claim 4, wherein the solvents in the to-be-detected acetyl terminated polyether sample solution and the derivatization reagent are both aprotic solvents.
6. The method for detecting trace acetic anhydride in acetyl terminated polyether as claimed in claim 5, wherein the solvent is tetrahydrofuran or acetonitrile.
7. The method for detecting trace acetic anhydride in acetyl terminated polyether according to claim 5, wherein the derivatization reagent is aniline solution.
8. The method for detecting trace acetic anhydride in acetyl terminated polyether according to claim 1, wherein the liquid chromatography conditions are:
a chromatographic column: a C18 column, the column length is 250mm, the inner diameter is 4.6mm, the granularity is 5 μm, or a chromatographic column with the same performance;
mobile phase: the organic phase is methanol or acetonitrile, and the water phase is deionized water;
flow rate: 0.3-2.0 mL/min;
column temperature: the room temperature is 50 ℃;
sample introduction amount: 1-100 μ L;
detection wavelength: 254 nm.
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| CN101013113A (en) * | 2007-01-31 | 2007-08-08 | 上海化学试剂研究所 | Highly effective liquid phase chromatogram analyzing method of N-phenyl maleimide |
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