Derivatization reaction liquid for measuring content of stearate in compound additive as well as application and measuring method of derivatization reaction liquid

Abstract

The invention belongs to the technical field of component analysis, and discloses a derivatization reaction solution for measuring the content of stearate in a compound additive and application and a measuring method of the derivatization reaction solution, and the derivatization reaction solution is a cyclohexanone mixed solution of concentrated sulfuric acid and aromatic alcohol. The method for determining the stearate by using the derivatization reaction liquid is not interfered by common antioxidants, antistatic agents, other metal element-containing substances and other components in the compound auxiliaries. While having anti-interference performance, the determination method provided by the invention has good accuracy and precision, and is suitable for quality control work of enterprises.

Description

Technical Field

[0001] The present invention relates to the technical field of component analysis, and more specifically to a derivatization reaction liquid for determining the content of stearate in a compounding auxiliary agent, and an application and a determination method thereof. Background Art

[0002] Polyolefin polymer materials are widely used in industrial production and daily life due to their characteristics of easy processing, light weight, high strength and low price. In order to make polyolefin materials have some special properties or improve their performance, compounding additives are usually added to them.

[0003] The ingredients in compounding additives generally include antioxidants, nucleating agents, antistatic agents, thermal stabilizers, acid absorbers, etc. Among them, antioxidants are used to inhibit the thermal oxidation degradation of polymers and extend their service life; nucleating agents can change the crystallization behavior of resins to shorten the molding cycle, improve the transparency and surface gloss of products, and improve physical and mechanical properties; antistatic agents can eliminate the accumulation of charges on the surface of plastics.

[0004] Stearates have many functions in polyolefin compounding additives: they can be used as heat stabilizers, softeners, lubricants, and film-forming agents; they can react with hydrochloric acid produced by the thermal decomposition of PVC to prevent decomposition; they are also very good light stabilizers, which can inhibit the aging of films by ultraviolet rays and extend the service life of agricultural films. Commonly used stearates in industry include: calcium stearate, zinc stearate, magnesium stearate, barium stearate, cadmium stearate, lead stearate, etc. Among them, calcium stearate accounts for about 60% and zinc stearate accounts for about 20%. They play a pivotal role in various plastics.

[0005] Generally speaking, in the production process of polyolefin polymer materials, various components including antioxidants, heat stabilizers, etc. are not added separately, but are first mixed by the additive manufacturer to form a compound additive package, and then added to the polymer material. The reasons are as follows: First, the process of adding the compound additive package at one time is simpler than adding additives multiple times, which reduces the operation steps of the process flow and can also make the mixing of additives and resin materials more uniform; secondly, there is a synergistic effect between some compound additives, which will enhance each other's performance. Adding them at the same time is more advantageous than adding them separately, such as the synergistic effect between the main antioxidant and the auxiliary antioxidant; in addition, the composition and formula of the compound additive are unique and confidential to the manufacturer. Selling the prepared compound additive as a whole can also protect the formula.

[0006] With the rapid increase in the output of synthetic materials worldwide, the global production capacity of compound additives has been promoted and stimulated to grow rapidly. The average annual growth rate of the production capacity of polyolefin additives has remained at about 8%. However, what is not commensurate with the rapid development of the production capacity of compound additives is the relative lag of its analysis and detection technology. At present, there is no complete set of technical solutions for analyzing all the components of compound additives. The reasons are as follows: First, there are many types of compound additives. For example, nucleating agents alone can be divided into fatty carboxylates, sorbitols, organic phosphates, etc. Each type can be divided into several generations according to the development time, and each generation contains a variety of products; secondly, it is difficult to separate the components in compound additives, and when determining the content of one of the substances, it is often affected by other species that exist at the same time, such as the presence of antioxidants will affect the observation of the titration end point of calcium content determination; in addition, the technology of compound additives is still developing, and new components are constantly being developed, which also constantly poses new challenges for the development of analytical methods.

[0007] There are currently no national or industry standards for the determination of stearate content in compounding additives. Industrial enterprises and inspection units generally use titration or spectroscopy to determine the content of metal elements, such as calcium in calcium stearate and zinc in zinc stearate, to infer the content of stearate. However, such methods all have insurmountable defects. When directly titrating calcium and zinc in compounding additives, organic components such as antioxidants will seriously affect the indicator's display of the titration end point. Even if the metal element content is obtained by digestion and then determined by spectroscopy or chemical separation, there are still problems in converting the stearate content. First, calcium, zinc, etc. are elements that are susceptible to environmental pollution; secondly, there may be other species containing similar metal elements in antioxidants; in addition, when the quality of the stearate raw materials used for compounding is poor, they may contain excessive metal elements. The above reasons reduce the accuracy of the method of inferring the stearate content by measuring the metal element content, or even make it completely unmeasurable. Summary of the invention

[0008] The purpose of the present invention is to provide a derivatization reaction liquid for determining the content of stearate in a compounding auxiliary agent, its application, and a method for determining the content of stearate in a compounding auxiliary agent. The determination method of the derivatization reaction liquid of the present invention is used to determine stearate without being interfered by components such as common antioxidants, antistatic agents, and other metal element-containing substances in compounding auxiliary agents. While having anti-interference properties, the determination method of the present invention also has good accuracy and precision, and is suitable for enterprises to carry out quality control work.

[0009] The first aspect of the present invention provides a derivatization reaction solution for determining the content of stearate in a compounding auxiliary agent. The derivatization reaction solution is a mixed solution of concentrated sulfuric acid and aromatic alcohol in cyclohexanone.

[0010] The second aspect of the present invention provides the use of the above-mentioned derivatization reaction solution as a color development reaction solution in a liquid chromatography detection method for the stearate content in a compounding auxiliary agent.

[0011] The third aspect of the present invention provides a method for determining the content of stearate in a compounding auxiliary agent, the determination method comprising method 1 or method 2:

[0012] Method 1: When the derivatized stearate standard solution is a single-point concentration, the determination method includes:

[0013] (1) contacting and reacting a stearate standard sample of the type to be detected with the derivatization reaction solution; after the reaction is completed, the reaction solution is fixed to a fixed volume to obtain a derivatized stearate standard solution;

[0014] (2) contacting and reacting the composite auxiliary agent sample to be tested with the above-mentioned derivatization reaction solution; after the reaction is completed, the reaction solution is fixed to a volume to obtain a solution to be tested;

[0015] (3) performing a liquid chromatography test on the derivatized stearate standard solution and the test solution, and obtaining the stearate content in the test compound auxiliary agent sample based on the liquid chromatograms of the derivatized stearate standard solution and the test solution;

[0016] Mode 2: When the derivatized stearate standard solution is a plurality of derivatized stearate standard solutions of a series of concentrations obtained by stepwise dilution, the determination method comprises:

[0017] (1) contacting and reacting a plurality of stearate standard samples of the intended detection type with the above-mentioned derivatization reaction solution respectively; after the reaction is completed, the plurality of reaction solutions are fixed to a fixed volume to obtain a plurality of derivatized stearate standard solutions;

[0018] (2) contacting and reacting the composite auxiliary agent sample to be tested with the above-mentioned derivatization reaction solution; after the reaction is completed, the reaction solution is fixed to a volume to obtain a solution to be tested;

[0019] (3) performing a liquid chromatography test on the multiple derivatized stearate standard solutions and the test solution, and obtaining the stearate content in the test compound auxiliary agent sample based on the liquid chromatograms of the multiple derivatized stearate standard solutions and the test solution.

[0020] The technical solution of the present invention has the following beneficial effects:

[0021] (1) The determination method of stearate using the derivatization reaction solution of the present invention can be free from interference from components such as antioxidants, antistatic agents, and other metal-containing substances commonly found in compounding additives.

[0022] (2) The present invention provides a method for testing the content of stearate in the field of compounding auxiliary agents, which is not interfered by other components, elemental pollution, or raw material quality;

[0023] (3) The determination method of the present invention has accurate results, high precision and good recovery rate;

[0024] (4) The determination method of the present invention is easy to operate and does not use highly toxic reagents, which is convenient for laboratories of compounding auxiliary agent production units and users to carry out application.

[0025] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0027] Figure 1 A schematic diagram showing a principle of an exemplary stearate derivatization reaction according to the present invention is shown.

[0028] Figure 2a and Figure 2b The liquid chromatogram of the derivatized stearate standard solution and the liquid chromatogram of the test solution according to Example 1 of the present invention are respectively shown; wherein the vertical axis represents the absorption peak.

[0029] Figure 2c The liquid chromatogram of the derivatized stearate standard solution according to Comparative Example 2 of the present invention is shown; wherein the vertical axis represents the absorption peak. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0031] The first aspect of the present invention provides a derivatization reaction solution for determining the content of stearate in a compounding auxiliary agent. The derivatization reaction solution is a mixed solution of concentrated sulfuric acid and aromatic alcohol in cyclohexanone.

[0032] According to the present invention, preferably, based on the total volume of the derivatization reaction solution, the volume content of the concentrated sulfuric acid is 1-10%, the volume content of the aromatic alcohol is 5-20%, and the balance is cyclohexanone.

[0033] According to the present invention, preferably, the aromatic alcohol includes at least one of benzyl alcohol, α-phenylethanol and β-phenylethanol.

[0034] According to the present invention, preferably, the mass concentration of the concentrated sulfuric acid is above 95%.

[0035] According to the present invention, preferably, the stearate includes at least one of calcium stearate, zinc stearate, lead stearate and barium stearate.

[0036] The second aspect of the present invention provides the use of the above-mentioned derivatization reaction solution as a color development reaction solution in a liquid chromatography detection method for the stearate content in a compounding auxiliary agent.

[0037] The third aspect of the present invention provides a method for determining the content of stearate in a compounding auxiliary agent, the determination method comprising method 1 or method 2:

[0038] Method 1: When the derivatized stearate standard solution is a single-point concentration, the determination method includes:

[0039] (1) contacting and reacting a stearate standard sample of the type to be detected with the derivatization reaction solution; after the reaction is completed, the reaction solution is fixed to a fixed volume to obtain a derivatized stearate standard solution;

[0040] (2) contacting and reacting the composite auxiliary agent sample to be tested with the above-mentioned derivatization reaction solution; after the reaction is completed, the reaction solution is fixed to a volume to obtain a solution to be tested;

[0041] (3) performing a liquid chromatography test on the derivatized stearate standard solution and the test solution, and obtaining the stearate content in the test compound auxiliary agent sample based on the liquid chromatograms of the derivatized stearate standard solution and the test solution;

[0042] Mode 2: When the derivatized stearate standard solution is a plurality of derivatized stearate standard solutions of a series of concentrations obtained by stepwise dilution, the determination method comprises:

[0043] (1) contacting and reacting a plurality of stearate standard samples of the intended detection type with the above-mentioned derivatization reaction solution respectively; after the reaction is completed, the plurality of reaction solutions are fixed to a fixed volume to obtain a plurality of derivatized stearate standard solutions;

[0044] (2) contacting and reacting the composite auxiliary agent sample to be tested with the above-mentioned derivatization reaction solution; after the reaction is completed, the reaction solution is fixed to a volume to obtain a solution to be tested;

[0045] (3) performing a liquid chromatography test on the multiple derivatized stearate standard solutions and the test solution, and obtaining the stearate content in the test compound auxiliary agent sample based on the liquid chromatograms of the multiple derivatized stearate standard solutions and the test solution.

[0046] Stearate is a common and important component in compounding additives. The existing method for determining the content of stearate in compounding additives is generally to determine the metal element content therein by titration or spectroscopy, and then convert it into stearate content. However, the sources of metal elements in compounding additives are diverse, easily contaminated, and affected by the quality of stearate raw materials. Therefore, the method of determining the metal element content and then converting it often results in a large measurement deviation, which cannot reflect the actual content of stearate in the compounding additive.

[0047] The inventors have found that stearate can form stearate esters with some alcohols in a dipolar solvent environment through the catalytic effect of concentrated sulfuric acid, such as Figure 1 As shown. Although the absorption of stearate itself in the ultraviolet band is very weak, through the above reaction, the stearate is subjected to a derivatization color development reaction using an alcohol substance with characteristic ultraviolet absorption, and the stearate content in the compound auxiliary sample can be determined on a conventional liquid chromatography ultraviolet detector. Based on the above principle, the present invention provides a method for first subjecting a compound auxiliary containing stearate to a derivatization reaction, and then determining the stearate content therein by high performance liquid chromatography using an ultraviolet detector or a diode array detector.

[0048] In the present invention, preferably, the derivatized stearate standard solution can be a single point, or a series of concentration standard solutions obtained by stepwise dilution.

[0049] According to the present invention, preferably, the volume is fixed with an aqueous solution of methanol;

[0050] The volume fraction of methanol in the aqueous solution of methanol is preferably 20%-80%.

[0051] Preferably, the reaction temperature is 120°C to 150°C, and the reaction time is 30 min-6 h.

[0052] In the present invention, preferably, the purity of the stearate standard sample of the type to be detected is not less than 98%.

[0053] According to the present invention, preferably, the chromatographic conditions of the liquid chromatography test include:

[0054] The chromatographic column is a reverse phase chromatographic column, preferably a C18 column;

[0055] The mobile phase is a methanol and water buffer salt mobile phase, and the volume content of the methanol is 20-60% based on the total volume of the methanol and water buffer salt mobile phase; the water buffer salt is a phosphate buffer system, and the pH of the phosphate buffer system is 2-4;

[0056] The flow rate of the mobile phase is 0.4-1.8 mL·min -1 , preferably 0.8-1.4 mL·min-1 ;

[0057] The wavelength of the detector is 220-300 nm, preferably 240-270 nm.

[0058] According to the present invention, preferably, in mode 1, in step (3), the stearate derivative peaks in the liquid chromatograms of the derivatized stearate standard solution and the solution to be tested are integrated respectively to obtain the chromatographic peak area of ​​the derivatized stearate standard solution and the chromatographic peak area of ​​the solution to be tested; then, a standard curve is prepared based on the amount of the stearate standard sample used when preparing the derivatized stearate standard solution and the chromatographic peak area of ​​the derivatized stearate standard solution, and the stearate content in the compound auxiliary agent sample to be tested is calculated by the external standard method;

[0059] In the second method, in step (3), the stearate derivative peaks in the liquid chromatograms of the multiple derivatized stearate standard solutions and the solution to be tested are integrated respectively to obtain the chromatographic peak areas of the multiple derivatized stearate standard solutions and the chromatographic peak areas of the solution to be tested; then, a standard curve is prepared based on the amounts of multiple stearate standard samples used when preparing the multiple derivatized stearate standard solutions and the chromatographic peak areas of the multiple derivatized stearate standard solutions, and the stearate content in the compound auxiliary agent sample to be tested is calculated by the external standard method.

[0060] In the present invention, preferably, in step (3), if it is necessary to identify the peak time of the aromatic alcohol, the methanol solution of the aromatic alcohol can also be tested under the same conditions.

[0061] The present invention is further described below by examples:

[0062] The instruments used for the test are:

[0063] Air heating jacket: DZTW temperature regulating heating jacket

[0064] Electronic balance: Mettler AE 200S electronic balance;

[0065] High performance liquid chromatography: Thermo Fisher Ultimate 3000 high performance liquid chromatograph.

[0066] The reagents used in the test are:

[0067] Concentrated sulfuric acid: analytical grade, mass concentration is 98%;

[0068] Cyclohexanone: analytical grade;

[0069] Benzyl alcohol: analytical grade;

[0070] Calcium stearate: analytical grade, purity 98%;

[0071] Zinc stearate: analytical grade, purity 98%.

[0072] Example 1

[0073] The composition of the compound auxiliary agent sample in this embodiment is as follows: based on the total weight of the compound auxiliary agent sample, it contains 25wt% calcium stearate, 25wt% antioxidant 168, 25wt% antioxidant 1010, and 25wt% calcium carbonate.

[0074] This embodiment provides a method for determining the content of stearate in a compounding auxiliary agent, which specifically comprises the following steps:

[0075] 1. Prepare a mixed solution of concentrated sulfuric acid and aromatic alcohol in cyclohexanone (derivation reaction solution). Add 3 mL of concentrated sulfuric acid and 10 mL of benzyl alcohol to about 10 mL of cyclohexanone, and then dilute to 50 mL with cyclohexanone.

[0076] 2. Weigh 0.1g analytical pure calcium stearate standard sample, accurate to 0.0001g, and place it in a flask. Add 25mL of the above derivatization reaction solution to the weighed standard sample, adjust the temperature of the air heating mantle to 140°C, and heat under reflux for 2h. After the reaction is completed, transfer the reaction solution to a 50mL volumetric flask and dilute it with a mixed solution of water: methanol = 1:1 (v / v) to obtain a derivatized stearate standard solution;

[0077] 3. Weigh 0.5 g of the compounded auxiliary agent sample to be tested, accurate to 0.0001 g, and place it in a flask. Add 25 mL of the derivatization reaction solution to the weighed compounded auxiliary agent sample to be tested, adjust the temperature of the air heating mantle to 140 ° C, heat and reflux for 2 h. After the reaction is completed, transfer the reaction solution to a 50 mL volumetric flask and make up to volume with a mixed solution of water: methanol = 1:1 (v / v) to obtain a solution to be tested.

[0078] 4. Prepare the liquid chromatography mobile phase as follows: prepare a 0.1 M sodium dihydrogen phosphate solution with premium grade sodium dihydrogen phosphate and first-grade water, and then adjust the pH to 3 with a 0.1 M phosphoric acid solution prepared with premium grade phosphoric acid and first-grade water. Mix the pH-adjusted solution with chromatographic grade methanol at a volume ratio of 1:1.

[0079] Set up high performance liquid chromatography (HPLC) conditions:

[0080] Chromatographic column: reverse phase C18 column;

[0081] Mobile phase flow rate: 1.2 mL min -1 ;

[0082] Detector wavelength: 254nm.

[0083] 5. Perform liquid chromatography test on the standard solution obtained in steps 2 and 3 and the solution to be tested under the chromatographic conditions set in step 4. Integrate the stearate derivative peak in the standard solution spectrum and the stearate derivative peak in the test solution spectrum to obtain the chromatographic peak area of ​​the derivatized stearate standard solution and the chromatographic peak area of ​​the test solution, and then prepare a standard curve based on the amount of the stearate standard sample used when preparing the derivatized stearate standard solution and the chromatographic peak area of ​​the derivatized stearate standard solution, and calculate the calcium stearate content in the compound auxiliary agent sample to be tested by the external standard method based on the chromatographic peak area of ​​the test solution and the standard curve.

[0084] The measured chromatogram is as follows Figure 2a and Figure 2b As shown in the figure, the peak at retention time 2.437min is the unreacted benzyl alcohol, which may be superimposed with unknown small molecular peaks; the peak at retention time 21min to 23min is the ester peak produced after stearic acid derivatization. The multiple peaks observed after the derivatization reaction of the compound auxiliary sample, except for benzyl alcohol and derivatives, are presumed to come from the antioxidant component, or the substance produced by the chemical change of the antioxidant component during the derivatization reaction.

[0085] The analytical method established in this example actually measured a calcium stearate content of 23.8 wt %. After 6 parallel tests, the results showed that the RSD (relative standard deviation) of the calcium stearate content test was 1.8%.

[0086] Example 2

[0087] The composition of the compound auxiliary agent sample in this embodiment is as follows: based on the total weight of the compound auxiliary agent sample, it contains 50wt% zinc stearate and 50wt% antioxidant 1076.

[0088] This embodiment provides a method for determining the content of stearate in a compounding auxiliary agent, which specifically comprises the following steps:

[0089] 1. Prepare a mixed solution of concentrated sulfuric acid and aromatic alcohol in cyclohexanone (derivation reaction solution). Add 2 mL of concentrated sulfuric acid and 5 mL of benzyl alcohol to about 10 mL of cyclohexanone, and then dilute to 50 mL with cyclohexanone.

[0090] 2. Weigh 0.1g, 0.2g, and 0.3g of analytical pure zinc stearate standard samples, accurate to 0.0001g, and place them in a flask. Add 25mL of derivatization reaction solution to each weighed standard sample, adjust the temperature of the air heating mantle to 130℃, and heat under reflux for 3h. After the reaction is completed, transfer the reaction solution of each standard sample to a 50mL volumetric flask, and dilute with a mixed solution of water: methanol = 7:3 (v / v) to obtain each derivatized stearate standard solution.

[0091] 3. Weigh 0.5 g of the compound auxiliary sample to be tested, accurate to 0.0001 g, and place it in a flask. Add 25 mL of the above-mentioned derivatization reaction solution to the weighed compound auxiliary sample to be tested, adjust the temperature of the air heating mantle to 130 ° C, and heat to reflux for 3 hours. After the reaction is completed, transfer the reaction solution to a 50 mL volumetric flask and make up to volume with a mixed solution of water: methanol = 7:3 (v / v) to obtain a solution to be tested.

[0092] 4. Prepare the liquid chromatography mobile phase as follows: prepare a 0.1M sodium dihydrogen phosphate solution with premium grade sodium dihydrogen phosphate and first-grade water, and then adjust the pH to 3.5 with a 0.1M phosphoric acid solution prepared with premium grade phosphoric acid and first-grade water. Mix the pH-adjusted solution with chromatographic grade methanol at a volume ratio of 7:3.

[0093] Set up high performance liquid chromatography (HPLC) conditions:

[0094] Chromatographic column: reverse phase C18 column;

[0095] Mobile phase flow rate: 1.0 mL min -1 ;

[0096] Detector wavelength: 254nm.

[0097] 5. Perform liquid chromatography test on each derivatized stearate standard solution and the solution to be tested obtained in steps 2 and 3 under the chromatographic conditions set in step 4. Integrate the stearate derivative peaks in the spectra of each standard solution and the stearate derivative peaks in the spectra of the solution to be tested, respectively, to obtain the chromatographic peak area of ​​each derivatized stearate standard solution and the chromatographic peak area of ​​the solution to be tested, and then prepare a standard curve based on the dosage of multiple stearate standard samples used when preparing the multiple derivatized stearate standard solutions and the chromatographic peak area of ​​each derivatized stearate standard solution, and calculate the zinc stearate content in the compound auxiliary agent sample to be tested by the external standard method based on the chromatographic peak area of ​​the solution to be tested and the standard curve.

[0098] The analysis method established in this example actually measured a zinc stearate content of 48.2 wt%. After 6 parallel tests, the results showed that the RSD of the zinc stearate content test was 2.2%.

[0099] Comparative Example 1:

[0100] The compounded auxiliary agent sample in this comparative example is the same as that in Example 1.

[0101] The comparative example adopts the traditional method of measuring the calcium content in the sample to infer the calcium stearate content.

[0102] 1. Weigh 0.1g analytical pure calcium stearate standard sample, accurate to 0.0001g, place it in a quartz crucible, burn it at 700℃ for 2h, dissolve it with 10mL high-grade pure concentrated nitric acid, transfer it to a 50mL volumetric flask, and make up to volume with deionized water.

[0103] 2. Weigh 0.5g of compound auxiliary agent sample, accurate to 0.0001g, and use the same method as in 1 to burn, dissolve and adjust the volume.

[0104] 3. Use ICP-OES instrument to measure the intensity of the solution obtained in 1 and 2 at 317.933 nm, and analyze the calcium stearate content in the sample by external standard method.

[0105] Since the calcium carbonate component in the sample also contains calcium, it interferes with the test of calcium stearate. According to the method in the comparative example, the result of the measurement is that the content of calcium stearate in the sample is 110.4%, which is inconsistent with the actual situation.

[0106] Comparative Example 2

[0107] The compounded auxiliary agent sample in this comparative example is the same as that in Example 1.

[0108] The difference between the determination method of the stearate content in this comparative example and that in Example 1 is that 2-hexanone is used instead of the cyclohexanone in Example 1, and the rest is the same as in Example 1.

[0109] In this comparative example, after the derivatization reaction, the measured liquid chromatogram of the derivatized stearate standard solution is as follows: Figure 2c As shown in the figure, there is only a small peak after the derivatization of stearate at 21min to 23min, and at the same time, there are multiple chromatographic peaks at the low retention time of the spectrum. According to the measured liquid chromatogram of the derivatized stearate standard solution, when 2-hexanone is used instead of cyclohexanone in Example 1, the derivatization reaction is incomplete, and there are also side reactions, which cannot meet the requirements of quantitative analysis of stearate content, and the standard curve cannot be obtained, and thus the calcium stearate content in the composite auxiliary agent sample to be tested cannot be obtained.

[0110] It can be seen from the results of the determination of stearate content in the compounding auxiliary agent of the embodiment that the determination method of the present invention has high precision and good recovery rate. It can be seen from the comparison of the embodiment and the comparative example that the determination method of the present invention can avoid the influence of other components containing the metal element in the sample when the stearate content is calculated by the metal element content in the traditional method, thereby realizing the accurate determination of the stearate content in such compounding auxiliary agent samples.

[0111] The invention provides a method for determining the content of stearate in a compound auxiliary agent. The method has the characteristics of accurate results, high precision and good recovery rate, and the determination results are not interfered by components such as common antioxidants, antistatic agents, and other metal element-containing substances in the compound auxiliary agent.

[0112] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A derivatization reaction solution for determining the content of stearate in a compounding auxiliary agent, characterized in that: The derivatization reaction solution is a mixed solution of concentrated sulfuric acid and aromatic alcohol in cyclohexanone.

2. The derivatization reaction solution according to claim 1, wherein: Based on the total volume of the derivatization reaction solution, the volume content of the concentrated sulfuric acid is 1-10%, the volume content of the aromatic alcohol is 5-20%, and the balance is cyclohexanone.

3. The derivatization reaction solution according to claim 1 or 2, wherein: The aromatic alcohol includes at least one of benzyl alcohol, α-phenylethanol and β-phenylethanol.

4. The derivatization reaction solution according to claim 1 or 2, wherein: The mass concentration of the concentrated sulfuric acid is above 95%.

5. The derivatization reaction solution according to claim 1 or 2, wherein: The stearate includes at least one of calcium stearate, zinc stearate, lead stearate and barium stearate.

6. Use of the derivatization reaction solution according to any one of claims 1 to 5 as a color development reaction solution in a liquid chromatography detection method for the stearate content in a compounding auxiliary agent.

7. A method for determining the content of stearate in a compounding auxiliary agent, characterized in that: The determination method includes method 1 or method 2: Method 1: When the derivatized stearate standard solution is a single-point concentration, the determination method includes: (1) contacting and reacting a stearate standard sample of the type to be detected with the derivatization reaction solution described in any one of claims 1 to 5; after the reaction is completed, the reaction solution is fixed to a constant volume to obtain a derivatized stearate standard solution; (2) contacting and reacting the composite auxiliary agent sample to be tested with the derivatization reaction solution described in any one of claims 1 to 5; after the reaction is completed, the reaction solution is fixed to a volume to obtain a solution to be tested; (3) performing a liquid chromatography test on the derivatized stearate standard solution and the test solution, and obtaining the stearate content in the test compound auxiliary agent sample based on the liquid chromatograms of the derivatized stearate standard solution and the test solution; Mode 2: When the derivatized stearate standard solution is a plurality of derivatized stearate standard solutions of a series of concentrations obtained by stepwise dilution, the determination method comprises: (1) contacting and reacting a plurality of stearate standard samples of the type to be detected with the derivatization reaction solution described in any one of claims 1 to 5; after the reaction is completed, the plurality of reaction solutions are fixed to a fixed volume to obtain a plurality of derivatized stearate standard solutions; (2) contacting and reacting the composite auxiliary agent sample to be tested with the derivatization reaction solution described in any one of claims 1 to 5; after the reaction is completed, the reaction solution is fixed to a volume to obtain a solution to be tested; (3) performing a liquid chromatography test on the multiple derivatized stearate standard solutions and the test solution, and obtaining the stearate content in the test compound auxiliary agent sample based on the liquid chromatograms of the multiple derivatized stearate standard solutions and the test solution.

8. The assay method according to claim 7, wherein The volume is fixed with an aqueous solution of methanol; The volume fraction of methanol in the aqueous solution of methanol is preferably 20%-80%. Preferably, the reaction temperature is 120°C to 150°C, and the reaction time is 30 min-6 h.

9. The assay method according to claim 7, wherein The chromatographic conditions of the liquid chromatography test include: The chromatographic column is a reverse phase chromatographic column, preferably a C18 column; The mobile phase is a methanol and water buffer salt mobile phase, and the volume content of the methanol is 20-60% based on the total volume of the methanol and water buffer salt mobile phase; the water buffer salt is a phosphate buffer system, and the pH of the phosphate buffer system is 2-4; The flow rate of the mobile phase is 0.4-1.8 mL·min -1 , preferably 0.8-1.4 mL·min -1 ; The wavelength of the detector is 220-300 nm, preferably 240-270 nm.

10. The measuring method according to claim 7, wherein In the first embodiment, in step (3), the stearate derivative peaks in the liquid chromatograms of the derivatized stearate standard solution and the solution to be tested are integrated to obtain the chromatographic peak area of ​​the derivatized stearate standard solution and the chromatographic peak area of ​​the solution to be tested; Then, a standard curve is prepared based on the amount of the stearate standard sample used when preparing the derivatized stearate standard solution and the chromatographic peak area of ​​the derivatized stearate standard solution, and the stearate content in the compound auxiliary agent sample to be tested is calculated by the external standard method; In the second method, in step (3), the stearate derivative peaks in the liquid chromatograms of the multiple derivatized stearate standard solutions and the solution to be tested are integrated respectively to obtain the chromatographic peak areas of the multiple derivatized stearate standard solutions and the chromatographic peak area of ​​the solution to be tested; Then, a standard curve is prepared based on the dosage of multiple stearate standard samples when preparing the multiple derivatized stearate standard solutions and the chromatographic peak areas of the multiple derivatized stearate standard solutions, and the stearate content in the compound auxiliary agent sample to be tested is calculated by the external standard method.

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