CN114295774A - Method for determining water content in insoluble hydrophilic polymer material by Karl Fischer method - Google Patents
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Abstract
The invention provides a novel method for measuring the water content in an insoluble hydrophilic polymer material (particularly a hard capsule shell of gelatin or plant fibers), namely, the method for measuring the water content in the insoluble hydrophilic polymer material by adopting a Karl Fischer method. The method provided by the invention not only solves the problem that the Karl Fischer method in the prior art can not measure the moisture content in the slightly soluble hydrophilic polymer material, but also greatly improves the analysis efficiency of the determination of the moisture content in the slightly soluble hydrophilic polymer material (compared with the hot drying method in the prior art, the method can be completed within 1-2 hours after the measurement time is 1-2 days).
Description
Technical Field
The invention relates to a method for measuring the moisture content in an insoluble hydrophilic polymer material, in particular to a method for measuring the moisture content in the insoluble hydrophilic polymer material by a Karl Fischer method, belonging to the field of food and medicine processing and detection.
Background
The capsule shell is the outer layer part of the capsule and is divided into a hard capsule shell and a soft capsule shell, wherein the hard capsule shell is mainly used for packaging solid medicines, and the soft capsule shell is mainly used for packaging liquid medicines. In the prior art, common plant fiber capsule shells and gelatin capsule shells belong to the category of hard capsule shells. The capsule shell has great influence on the properties of the capsule shell, such as plasticity, elasticity, wall thickness, disintegration time limit and viscosity (excessive adhesion can cause mutual adhesion of capsules). The amount of water used also has a varying degree of influence on the properties of the capsule shell depending on the type of gelatin/vegetable fibre used. Therefore, it is extremely important and significant to accurately determine the water content in the capsule shell.
In the prior art, the determination of the water content in the hard capsule shell mainly adopts a thermal drying method, namely, a thermal oven is adopted to carry out water air drying on the capsule shell to measure the water content in the capsule shell. However, the hot drying method has the defects of long air drying time and low efficiency of the detection method.
The method for measuring the moisture in the substance by the Karl Fischer method is an important and sensitive electrochemical analysis method and has the characteristics of accurate measurement and high efficiency. The principle of Karl Fischer method for measuring substance water content is that when the Karl Fischer reagent in the electrolytic cell of the instrument is balanced, a sample containing water is injected, water takes part in the oxidation-reduction reaction of iodine and sulfur dioxide, under the condition of existence of pyridine and methanol, pyridine hydroiodide and pyridine methylsulfate are generated, consumed iodine is generated by anode electrolysis, so that the oxidation-reduction reaction is continuously carried out until all water is consumed, according to Faraday's law, the iodine generated by electrolysis is in direct proportion to the electricity consumed during electrolysis, and the reaction is as follows:
H2O+I2+SO2+3C5H5N→2C5H5N·HI+C5H5N·SO3
C5H5N·SO3+CH3OH→C5H5N·HSO4CH3
during electrolysis, the electrode reactions are as follows:
anode 2I-2 e → I2
Cathode I2+2e→2I-
2H++2e→H2↑
It can be seen from the above reaction that 1 mole of iodine oxidizes 1 mole of sulfur dioxide, requiring 1 mole of water. Therefore, 1 mole of iodine reacts with 1 mole of water in equivalent, i.e., the amount of electricity of the electrolyzed iodine corresponds to the amount of electricity of the electrolyzed water.
Although the karl fischer method has been widely popularized for measuring the moisture content in substances, it cannot be applied to the moisture measurement in the insoluble hydrophilic polymer materials like the hard capsule shells of medicines such as plant fibers or gelatin.
Disclosure of Invention
The first purpose of the invention is to provide a method for measuring the moisture content in the slightly soluble hydrophilic polymer material by a Karl Fischer method, which can obviously shorten the time consumed by the method for measuring the moisture content in the slightly soluble hydrophilic polymer material and improve the analysis efficiency of measuring the moisture content in the slightly soluble hydrophilic polymer material.
A method for measuring the moisture content in a slightly soluble hydrophilic polymer material by a Karl Fischer method comprises the following steps:
(1) sample pretreatment: pretreating a sample by using anhydrous dispersion liquid, and extracting water in the sample to obtain an extraction liquid;
(2) and (3) moisture determination: and (3) feeding the extraction liquid into a Karl Fischer moisture tester, measuring the moisture in the extraction liquid and calculating the moisture content in the sample.
The sample refers to a sample whose moisture content is to be measured, i.e., a poorly soluble hydrophilic polymer material. The "hardly soluble hydrophilic polymer material" in the present invention means a polymer material having a certain water-absorbing ability but hardly soluble in a Karl Fischer reagent, and water in the polymer material is hardly extracted into the Karl Fischer reagent. Wherein the expression "hardly soluble in Karl Fischer's reagent" means that the sample is placed in the Karl Fischer's reagent and cannot be completely dissolved in the Karl Fischer's reagent within 3 minutes; wherein, the term "has a certain water absorption capacity" means that the polymer material can absorb water in the environment, but the water content of the material is not more than 30%; the phrase "moisture in the polymer material is hardly extracted into the karl fischer reagent" means that the sample is placed in the karl fischer reagent, and the moisture in the sample cannot be completely transferred to the karl fischer reagent within 3 minutes.
The anhydrous dispersion liquid is an amphiphilic molecular substance which has a hydrophobic group and a hydrophilic group on the structure and does not chemically react with a Karl Fischer reagent and an insoluble hydrophilic polymer material; the method can extract the water in the insoluble hydrophilic polymer material and transfer the water to the Karl Fischer reagent.
In some embodiments, the poorly soluble hydrophilic polymeric material is gelatin, plant fiber, or the like.
In some embodiments, the poorly soluble hydrophilic polymeric material is a gelatin hard capsule shell or a plant fiber hard capsule shell of a drug. Wherein the gelatin hard capsule shell is hard capsule shell with gelatin as main ingredient; the plant fiber hard capsule shell is a hard capsule shell taking plant fiber as a main component.
In some embodiments, the anhydrous dispersion liquid is selected from the group consisting of nonionic surfactants, cationic surfactants, anionic surfactants, C1-C5A monobasic organic acid, a dibasic organic acid, a tribasic organic acid, C1-C4And one or more of monohydric alcohol, dihydric alcohol, trihydric alcohol and N, N-dimethylformamide.
Wherein, C1-C5Refers to an organic compound having 1, 2,3, 4, or 5 carbon atoms, including C1- C4、C1-C3Or C1-C2Lower member ranges such as the organic compound of (1); same as C1-C4Refers to an organic compound of 1, 2,3 or 4 carbon atoms, which also includes C1-C3Or C1-C2The lower member of the organic compound (1).
In some embodiments, the anhydrous dispersion liquid is selected from anhydrous C1-C4Wherein C is one or a mixture of two or more of monohydric alcohol and dihydric alcohol1-C4Monohydric alcohols of (a) include, but are not limited to, methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, tert-butanol; c1-C4The dihydric alcohol of (a) includes, but is not limited to, ethylene glycol, propylene glycol, 2, 3-butanediol, 1, 3-butanediol.
In some embodiments, the anhydrous dispersion liquid is preferably selected from anhydrous ethanol.
In some embodiments, the anhydrous dispersion liquid is selected from N, N-dimethylformamide.
In some embodiments, the anhydrous dispersion liquid is selected from any proportional combination of anhydrous ethanol and N, N-dimethylformamide.
In some embodiments, the anhydrous dispersion liquid is selected from anhydrous C1-C5Wherein C is one or a mixture of two or more of a monobasic organic acid and a dibasic organic acid1-C5The monobasic organic acids of (a) include, but are not limited to, formic acid, acetic acid, propionic acid, isopropylic acid, n-butyric acid, sec-butyric acid, tert-butyric acid, valeric acid, etc.; c1-C5The dibasic organic acids of (a) include, but are not limited to, oxalic acid, malonic acid, succinic acid, glutaric acid, and the like.
In some embodiments, step (1) pre-treating the sample with the non-aqueous dispersion liquid comprises sonicating the sample in the non-aqueous dispersion liquid until the water in the sample is completely transferred to the non-aqueous dispersion liquid.
The second invention of the present invention is to provide a sample pretreatment method for determining the water content in the insoluble hydrophilic polymer material by the karl fischer method, which makes it possible to use the karl fischer method for determining the water content in the insoluble hydrophilic polymer material (such as gelatin, plant fiber, medicine gelatin capsule shell, plant fiber capsule shell, etc.); can obviously improve the water content determination and analysis efficiency in insoluble hydrophilic polymer materials (such as gelatin, plant fibers, medicine gelatin capsule shells, plant fiber capsule shells and the like).
A sample pretreatment method for measuring the water content in an insoluble hydrophilic polymer material by a Karl Fischer method comprises the following steps: (1) and (3) pretreating the sample by using anhydrous dispersion liquid, and extracting water in the sample to obtain an extraction liquid.
The extraction liquid is a sample for measuring the water content by a Karl Fischer method.
The sample refers to a sample whose moisture content is to be measured, i.e., a poorly soluble hydrophilic polymer material. The insoluble hydrophilic polymer material is a polymer material which has a certain water absorption capacity but is insoluble in the Karl Fischer reagent, and the water in the polymer material is difficult to extract into the Karl Fischer reagent; wherein the expression "hardly soluble in Karl Fischer's reagent" means that the sample is placed in the Karl Fischer's reagent and cannot be completely dissolved in the Karl Fischer's reagent within 3 minutes; wherein, the term "has a certain water absorption capacity" means that the polymer material can absorb water in the environment, but the water content of the material is not more than 30%; the phrase "moisture in the polymer material is hardly extracted into the karl fischer reagent" means that the sample is placed in the karl fischer reagent, and the moisture in the sample cannot be completely transferred to the karl fischer reagent within 3 minutes.
The anhydrous dispersion liquid is an amphiphilic molecular compound which has a hydrophobic group and a hydrophilic group on the structure and does not chemically react with a Karl Fischer reagent and an insoluble hydrophilic polymer material; the method can extract the water in the insoluble hydrophilic polymer material and transfer the water to the Karl Fischer reagent.
In some embodiments, the poorly soluble hydrophilic polymeric material is selected from gelatin, plant fibers, and the like.
In some embodiments, the insoluble hydrophilic polymer material is a gelatin hard capsule shell or a plant fiber hard capsule shell of a capsule drug.
In some embodiments, the anhydrous dispersion liquid is selected from the group consisting of nonionic surfactants, cationic surfactants, anionic surfactants, C1-C5A monobasic organic acid, a dibasic organic acid, a tribasic organic acid, C1-C4And one or more of monohydric alcohol, dihydric alcohol, trihydric alcohol and N, N-dimethylformamide.
Wherein, C1-C5Refers to an organic compound having 1, 2,3, 4, or 5 carbon atoms, including C1- C4、C1-C3Or C1-C2A range of individual members of (a); same as C1-C4Refers to an organic compound of 1, 2,3 or 4 carbon atoms, which also includes C1-C3Or C1-C2And the like, and the like.
In some embodiments, the anhydrous dispersion liquid is selected from anhydrous C1-C4One or a mixture of two or more of monohydric alcohol and dihydric alcohol, wherein C1-C4Monohydric alcohols of (a) include, but are not limited to, methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, tert-butanol; c1-C4The dihydric alcohol of (a) includes, but is not limited to, ethylene glycol, propylene glycol, 2, 3-butanediol, 1, 3-butanediol.
In some embodiments, the anhydrous dispersion liquid is preferably selected from anhydrous ethanol.
In some embodiments, the anhydrous dispersion liquid is selected from N, N-dimethylformamide.
In some embodiments, the anhydrous dispersion liquid is selected from any proportional combination of anhydrous ethanol and N, N-dimethylformamide.
In some embodiments, the anhydrous dispersion liquid is selected from anhydrous C1-C5Wherein C is one or a mixture of two or more of a monobasic organic acid or a dibasic organic acid1-C5The monobasic organic acids of (a) include, but are not limited to, formic acid, acetic acid, propionic acid, isopropylic acid, n-butyric acid, sec-butyric acid, tert-butyric acid, valeric acid, etc.; c1-C5The dibasic organic acids of (a) include, but are not limited to, oxalic acid, malonic acid, succinic acid, glutaric acid, and the like.
In some embodiments, step (1) pre-treating the sample with the non-aqueous dispersion liquid comprises sonicating the sample in the non-aqueous dispersion liquid until the water in the sample is completely transferred to the non-aqueous dispersion liquid.
The invention has the beneficial effects that: the invention provides a novel method for measuring the water content in an insoluble hydrophilic polymer material (particularly gelatin or a medicine capsule shell), namely, a Karl Fischer method is adopted to measure the water content in the insoluble hydrophilic polymer material. The method provided by the invention not only solves the problem that the Karl Fischer method in the prior art can not measure the moisture content in the slightly soluble hydrophilic polymer material, but also greatly improves the analysis efficiency of the determination of the moisture content in the slightly soluble hydrophilic polymer material (compared with the hot drying method in the prior art, the method can be completed within 1-2 hours after the measurement time is 1-2 days).
Detailed Description
The invention discloses a novel method for measuring the water content in an insoluble hydrophilic polymer material (particularly gelatin or a medicine capsule shell), namely, a Karl Fischer method is adopted to measure the water content in the insoluble hydrophilic polymer material. Those skilled in the art can modify the process parameters appropriately to achieve the desired results with reference to the disclosure herein. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the method and process parameters of the present invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the method steps and process parameters described herein may be made and used without departing from the spirit and scope of the invention.
In order to better illustrate the advantages of the invention, the capsule shell samples of the same batch are used as samples to be tested in the embodiment 1, the embodiment 2, the comparative example 1 and the comparative example 2, the main component of the samples is gelatin, and the gelatin is a macromolecular hydrophilic colloid and belongs to one of the insoluble hydrophilic macromolecular materials.
Example 1 determination of moisture content in Capsule Shell by Karl Fischer method
Step (1), sample pretreatment:
blank sample solution and sample solution preparation:
blank sample solution: placing 10ml of N, N-dimethylformamide into a sample tube, and sealing; then placing in an ultrasonic instrument for ultrasonic treatment for 20 min.
Sample solution: taking capsule shell M6(203.67mg) and 10ml of N, N-dimethylformamide were put in a sample tube and sealed; then placing in an ultrasonic instrument for ultrasonic treatment for 20 min.
Step (2) moisture determination:
moisture calibration with a karl fischer instrument: precisely weighing 20 μ l of pure water, placing in Karl Fischer water titrator for calibration, repeatedly calibrating for three times, and calculating the average value d of the titer of the three times1(4.3596mg/ml) and relative standard deviation.
And (3) moisture determination: after the moisture meter is calibrated, balancing the instrument;
precisely transferring 5ml of blank sample solution into a moisture meter, then titrating, and recording the volume V of the Karl Fischer test solution consumed at the end point of titration1(0.2325ml)；
Precisely transferring 5ml of sample solution, placing in a moisture meter, titrating, and recording the volume V of Karl Fischer test solution consumed at the end point of titration2(2.5875ml)
The result formula is: moisture%2-V1)×d1)/M6×100％
And (4) calculating a result: water% ((2.5875-0.2325) × 4.3596)/203.06 × 100%: 10.0%
The whole process is time-consuming: and (4) 1 h.
Example 2 determination of moisture content in Capsule Shell by Karl Fischer method
The experimental procedure and method were the same as those of example 1, except that N, N-dimethylformamide in step (1) was replaced with absolute ethanol.
Final moisture measurement: 10.0 percent.
Comparative example 1 determination of moisture content in Capsule Shell by Hot drying method
(1) Weighing a bottle for constant weight:
taking 2 flat weighing bottles (weighing bottle A and weighing bottle B), drying in an oven at 105 ℃ for 3h, taking out, and cooling to room temperature in a dryer. Weighing the weight M of the weighing bottle by a one-ten-thousandth balance1(M1AAnd M1B)。
After weighing, the mixture is continuously placed in an oven at 105 ℃ for drying for 1h, and then taken out and placed in a dryer for cooling to room temperature. Weighing the weight M of the weighing bottle by a one-ten-thousandth balance2(M2AAnd M2B)。
The absolute value of the difference between the two weighed weights is less than or equal to 0.3mg, and the two steps are continuously repeated when the absolute value is more than 0.3 mg; until the absolute value of the difference between the two successive weights is less than or equal to 0.3 mg.
The final weighing results are recorded as follows:
M1A＝27.4471g，M1B＝28.9671g；M2A＝27.4473g，M2B＝28.9672g；
(2) weighing a test sample:
taking a proper amount of capsule shells, and weighing M in one ten-thousandth balance3(M3A＝0.2029g,M3B0.2026g), cut into pieces and spread in a deformable weighing bottle.
(3) Constant weight of the test sample:
putting the flat weighing bottle filled with the capsule shell into a drying oven at 105 ℃, drying for 3h, taking out, and putting into a dryer to cool to room temperature; weighing M with one ten thousandth balance4(M4A＝27.6297g,M4B＝29.1493g)；
After weighing, continuously placing the mixture in a 105 ℃ drying oven for drying for 1h, taking out the mixture and placing the mixture in a dryer for cooling to room temperature; weighing M with one ten thousandth balance5(M5A＝27.6296g，M5B＝29.1495g)；
The absolute value of the difference between the two weighed weights is less than or equal to 0.3mg, and the step 1.3.2 is repeated when the absolute value is more than 0.3 mg. Until the absolute value of the difference between the two successive weights is less than or equal to 0.3 mg.
(4) And (5) result settlement:
loss on drying ═ M2+M3)-M5)/M3×100％
Sample 1 (sample in weigh vial a) had a loss on drying of: ((27.4473+0.2029) -27.6296)/0.2029 × 100% ═ 10.2%
Sample 2 (sample in weigh bottle B) had a loss on drying of: ((28.9672+0.2026) -29.1495)/0.2026 × 100% ═ 10.0%
The average loss on drying was: (10.2% + 10.0%)/2 ═ 10.1%
The whole process is time-consuming: 1.5 d.
Comparative example 2 determination of moisture content in Capsule Shell by Karl Fischer method-lack of N, N-dimethylformamide dissolution step
Step (1), sample treatment:
taking capsule shell, cutting into pieces with length and width less than 1cm, and weighing M7(200.53mg)。
Step (2) moisture determination:
moisture calibration with a karl fischer instrument: precisely weighing 20ul of pure water, placing in a Karl Fischer water titrator for calibration, repeatedly calibrating for three times, and calculating the average value d of the titer of the three times2(4.2352mg/ml) and relative standard deviation.
And (3) moisture determination: after the moisture meter is calibrated, balancing the instrument;
sending the sample treated in the step (1) into a moisture meter, then titrating, and recording the volume V of the Karl Fischer test solution consumed at the titration end point3(0.1530ml)。
And (4) calculating a result: water content ═ V3×d2)/M7×100％＝(0.1530×4.2352)/200.53×100％＝0.32％
The whole process is time-consuming: and (4) 1 h.
The capsule shells of the samples to be tested of the examples 1, 2, 1 and 2 are the same batch of raw materials, and the moisture measurement result (0.32%) of the sample of the comparative example 2 is greatly different from the moisture measurement result (about 10%) of the samples of the examples 1, 2 and 1. The reason was observed and analyzed: the capsule shell can not be completely dissolved and dispersed in the Karl Fischer reagent, so that the Karl Fischer moisture tester can not accurately measure the moisture content in the capsule shell.
By combining the above embodiments and comparative examples, it can be seen that the method for determining moisture in an insoluble hydrophilic polymer material (particularly gelatin) provided by the present application not only solves the problem that the karl fischer method in the prior art cannot measure the moisture content in the insoluble hydrophilic polymer material, but also greatly improves the analysis efficiency for determining the moisture content in the insoluble hydrophilic polymer material.
The foregoing detailed description of the invention has been presented for purposes of illustration and description, and is intended to be by way of illustration only and is not intended to limit the scope of the invention, its application, or uses, including the best mode, of manufacture, of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Claims (10)
1. A method for measuring the moisture content in a slightly soluble hydrophilic polymer material by a Karl Fischer method comprises the following steps:
(1) sample pretreatment: pretreating a sample by using anhydrous dispersion liquid, and extracting water in the sample to obtain an extraction liquid;
(2) and (3) moisture determination: feeding the extract liquor into a Karl Fischer moisture tester, measuring the moisture in the extract liquor and calculating the moisture content in the sample;
the anhydrous dispersion liquid is an amphiphilic molecular substance which has a hydrophobic group and a hydrophilic group on the structure and does not chemically react with a Karl Fischer reagent and an insoluble hydrophilic polymer material; the method can extract the water in the insoluble hydrophilic polymer material and transfer the water to the Karl Fischer reagent.
2. The method for determining the moisture content in a poorly soluble hydrophilic polymer material according to claim 1, which comprises: the insoluble hydrophilic polymer material is gelatin, plant fiber or the like.
3. The method for determining the moisture content in a poorly soluble hydrophilic polymer material by the karl fischer method according to claim 1 or 2, wherein: the insoluble hydrophilic polymer material is a gelatin hard capsule shell or a plant fiber hard capsule shell of a medicament.
4. The method for determining the moisture content in a poorly soluble hydrophilic polymer material according to claim 1, which comprises: the nonaqueous dispersion liquid is selected from the group consisting of nonionic surfactants, cationic surfactants, anionic surfactants, C1-C5A monobasic organic acid, a dibasic organic acid, a tribasic organic acid, C1-C4And one or more of monohydric alcohol, dihydric alcohol, trihydric alcohol and N, N-dimethylformamide.
5. The method for determining the moisture content in a poorly soluble hydrophilic polymer material according to claim 4, wherein: the anhydrous dispersion liquid is selected from anhydrous C1-C4Wherein C is one or a mixture of two or more of monohydric alcohol and dihydric alcohol1-C4Monohydric alcohols of (a) include, but are not limited to, methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, tert-butanol; c1-C4The dihydric alcohol of (a) includes, but is not limited to, ethylene glycol, propylene glycol, 2, 3-butanediol, 1, 3-butanediol.
6. The method for determining the moisture content in a poorly soluble hydrophilic polymer material according to claim 4, wherein: the anhydrous dispersion liquid is preferably selected from anhydrous ethanol or N, N-dimethylformamide, or any combination thereof.
7. The method for determining the moisture content in a poorly soluble hydrophilic polymer material according to claim 4, wherein: the anhydrous dispersion liquid is selected from anhydrous C1-C5Wherein C is one or a mixture of two or more of a monobasic organic acid and a dibasic organic acid1-C5The monobasic organic acid includes, but is not limited to, formic acid, acetic acid, propionic acid, isopropylic acid, n-butyric acid, sec-butyric acid, tert-butyric acid, valeric acidEtc.; c1-C5The dibasic organic acids of (a) include, but are not limited to, oxalic acid, malonic acid, succinic acid, glutaric acid, and the like.
8. The method for determining the moisture content in a poorly soluble hydrophilic polymer material according to any one of claims 1 to 7 by the Karl Fischer method, wherein: and (2) pretreating the sample by using the anhydrous dispersion liquid, namely placing the sample into the anhydrous dispersion liquid for ultrasonic treatment until the water in the sample is completely transferred into the anhydrous dispersion liquid.
9. A sample pretreatment method for measuring the water content in an insoluble hydrophilic polymer material by a Karl Fischer method comprises the following steps: (1) pretreating a sample by using anhydrous dispersion liquid, and extracting water in the sample to obtain an extraction liquid;
the anhydrous dispersion liquid is an amphiphilic molecular compound which has a hydrophobic group and a hydrophilic group on the structure and does not chemically react with a Karl Fischer reagent and an insoluble hydrophilic polymer material; the method can extract the water in the insoluble hydrophilic polymer material and transfer the water to the Karl Fischer reagent;
preferably, the slightly soluble hydrophilic polymer material is selected from gelatin, plant fiber and the like;
preferably, the insoluble hydrophilic polymer material is a gelatin hard capsule shell or a plant fiber hard capsule shell of a capsule drug;
preferably, the anhydrous dispersion liquid is selected from the group consisting of nonionic surfactants, cationic surfactants, anionic surfactants, C1-C5A monobasic organic acid, a dibasic organic acid, a tribasic organic acid, C1-C4One or more than two of monohydric alcohol, dihydric alcohol, trihydric alcohol and N, N-dimethylformamide are mixed;
preferably, the anhydrous dispersion liquid is selected from anhydrous C1-C4One or a mixture of two or more of monohydric alcohol and dihydric alcohol, wherein C1-C4Include but are not limited toLimited to methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, tert-butanol; c1-C4The dihydric alcohols of (a) include, but are not limited to, ethylene glycol, propylene glycol, 2, 3-butanediol, 1, 3-butanediol;
preferably, the anhydrous dispersion liquid is selected from anhydrous C1-C5Wherein C is one or a mixture of two or more of a monobasic organic acid or a dibasic organic acid1-C5The monobasic organic acids of (a) include, but are not limited to, formic acid, acetic acid, propionic acid, isopropylic acid, n-butyric acid, sec-butyric acid, tert-butyric acid, valeric acid, etc.; c1-C5The dibasic organic acids of (a) include, but are not limited to, oxalic acid, malonic acid, succinic acid, glutaric acid, and the like;
most preferably, the anhydrous dispersion liquid is preferably selected from anhydrous ethanol or N, N-dimethylformamide, or any combination thereof.
10. The method for pretreating a sample for measuring the water content in a poorly soluble hydrophilic polymer material by the Karl Fischer method according to claim 9, wherein the method comprises the following steps: and (2) pretreating the sample by using the anhydrous dispersion liquid in the step (1), wherein the step comprises the step of placing the sample into the anhydrous dispersion liquid for ultrasonic treatment until the water in the sample is completely transferred into the anhydrous dispersion liquid.
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