Detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier

Abstract

The present invention belongs to the technical field of analytical detection, relates to the detection of impurities, and specifically relates to a method for detecting 2,3-dihydroxypropyl-trimethylammonium chloride in a cationic modifier. A cationic modifier containing 2,3-dihydroxypropyl-trimethylammonium chloride is diluted with a 0.05-0.15% heptafluorobutyric acid solution by volume to obtain a sample to be tested, and the sample to be tested is analyzed by ion chromatography; the chromatographic column is a C18 reverse-phase chromatographic column, the detector is a conductivity detector, and the suppressor is a cation suppressor; a 0.35-0.45% heptafluorobutyric acid solution by volume is used as phase A, a 45-55% acetonitrile solution by volume is used as phase B, and ultrapure water is used as phase C; the present invention can achieve quantitative detection of 2,3-dihydroxypropyl-trimethylammonium chloride in the cationic modifier, and this method has the advantages of simple sample pretreatment and operation, low detection limit, accurate results, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of analytical detection, relates to the detection of impurities, and particularly relates to a method for detecting 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier. Background Art

[0002] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] The cationic modifier 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTMAC) is a quaternary ammonium salt cationic modifier with reactive groups. In the process of preparing the cationic modifier by the aqueous phase method, the residual reactants and the by-products generated are difficult to remove in the later purification process. Among them, 2,3-dihydroxypropyl-trimethyl ammonium chloride, as a by-product in the reaction process, has a great influence on the quality of the product. As far as the inventor knows, due to the small content of 2,3-dihydroxypropyl-trimethyl ammonium chloride in the cationic modifier product, to detect its content, the traditional chemical analysis methods cannot meet the requirements of analysis accuracy. At the same time, under the conditions of gas chromatography, 2,3-dihydroxypropyl-trimethyl ammonium chloride will decompose and cannot be vaporized, which will pollute the gas chromatography column and cannot obtain accurate results. The previously widely used high performance liquid chromatography method has the disadvantages of large consumption of mobile phase (3.98 g of sodium octanesulfonate, 116 g of sodium perchlorate, 132 g of methanol and 1750 g of ultrapure water), high detection cost, weak retention, poor peak shape and incomplete separation.

[0004] The present invention intends to use ion chromatography for detection. However, according to the further research of the inventor, when 2,3-dihydroxypropyl-trimethyl ammonium chloride is detected by ion chromatography, the problems encountered are the same as those encountered in the previous study of trimethylamine hydrochloride, that is, the cations of the cationic modifier and 2,3-dihydroxypropyl-trimethyl ammonium chloride are both quaternary ammonium cations, which are greatly affected by the matrix. Therefore, the inventor used the method of detecting trimethylamine hydrochloride by ion chromatography in the previous study to detect 2,3-dihydroxypropyl-trimethyl ammonium chloride. However, the experiment found that this method still cannot achieve the separation of 2,3-dihydroxypropyl-trimethyl ammonium chloride. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the object of the present invention is to provide a method for detecting 2,3-dihydroxypropyl-trimethylammonium chloride in a cationic modifier, which can quantitatively detect 2,3-dihydroxypropyl-trimethylammonium chloride in the cationic modifier. This method has the advantages of simple sample pretreatment and operation, low detection limit, and accurate results.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] On the one hand, a method for detecting 2,3-dihydroxypropyl-trimethylammonium chloride in a cationic modifier dilutes the cationic modifier containing 2,3-dihydroxypropyl-trimethylammonium chloride with a 0.05-0.15% heptafluorobutyric acid solution by volume to obtain a sample to be tested, and performs ion chromatography analysis on the sample to be tested;

[0008] During the ion chromatography analysis, the chromatographic column is a C18 reversed-phase chromatographic column, the detector is a conductivity detector, and the suppressor is a cation suppressor; in the eluent, a 0.35-0.45% heptafluorobutyric acid solution by volume is used as phase A, a 45-55% acetonitrile solution by volume is used as phase B, and ultrapure water is used as phase C;

[0009] The gradient elution conditions are as follows: during the period of 0-5 minutes, the volume fraction of phase A is 29.5-30.5%, the volume fraction of phase B is 4.5-5.5%, and the balance is phase C; during the period of 5-7 minutes, the volume fraction of phase A decreases from 29.5-30.5% to 9.5-10.5%, the volume fraction of phase B is 4.5-5.5%, and the balance is phase C; during the period of 7-8 minutes, the volume fraction of phase A is 9.5-10.5%, the volume fraction of phase B increases from 4.5-5.5% to 14.5-15.5%, and the balance is phase C; during the period of 8-9 minutes, the volume fraction of phase A is 9.5-10.5%, the volume fraction of phase B increases from 14.5-15.5% to 29.5-30.5%, and the balance is phase C; during the period of 9-13 minutes, the volume fraction of phase A is maintained at 9.5-10.5%, the volume fraction of phase B is maintained at 29.5-30.5%, and the balance is phase C; during the period of 13-13.1 minutes, the volume fraction of phase A increases from 9.5-10.5% to 29.5-30.5%, the volume fraction of phase B decreases from 29.5-30.5% to 4.5-5.5%, and the balance is phase C; during the period of 13.1-20 minutes, the volume fraction of phase A is 29.5-30.5%, the volume fraction of phase B is 4.5-5.5%, and the balance is phase C; within each time period, the total volume of phase A, phase B, and phase C is 100%.

[0010] On the other hand, an application of a detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in the above cationic modifier in the quality control of the production process of the cationic modifier.

[0011] The beneficial effects of the present invention are as follows:

[0012] By selecting a chromatographic column, a conductivity detector, and a cation suppressor, the present invention eliminates the interference of the cationic etherifying agent matrix and other impurities on the substance to be measured; by selecting a pretreatment solvent, a eluent, and controlling a gradient elution program, the complete separation of 2,3-dihydroxypropyl-trimethyl ammonium chloride is achieved, so that the 2,3-dihydroxypropyl-trimethyl ammonium chloride in the cationic modifier can be detected. Through experiments, it is proved that the detection method of the present invention has a low detection limit (0.1 μg / mL), accurate results; the sample pretreatment and detection processes are simple to operate. Description of the Drawings

[0013] The attached drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0014] Figure 1 It is the standard curve drawn in the embodiment of the present invention. Detailed Embodiments

[0015] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0016] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0017] Based on the fact that it is difficult to detect 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier by existing methods, the present invention proposes a detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier.

[0018] In a typical embodiment of the present invention, a method for detecting 2,3-dihydroxypropyl-trimethylammonium chloride in a cationic modifier is provided. A cationic modifier containing 2,3-dihydroxypropyl-trimethylammonium chloride is diluted with a 0.05 - 0.15% by volume solution of heptafluorobutyric acid to obtain a sample to be tested, and the sample to be tested is subjected to ion chromatography analysis;

[0019] During the ion chromatography analysis, the chromatographic column is a C18 reversed-phase chromatographic column, the detector is a conductivity detector, and the suppressor is a cation suppressor; in the eluent, a 0.35 - 0.45% by volume solution of heptafluorobutyric acid is used as phase A, a 45 - 55% by volume acetonitrile solution is used as phase B, and ultrapure water is used as phase C;

[0020] The gradient elution conditions are as follows: during the period from 0 to 5 minutes, the volume fraction of phase A is 29.5 - 30.5%, the volume fraction of phase B is 4.5 - 5.5%, and the balance is phase C; during the period from 5 to 7 minutes, the volume fraction of phase A decreases from 29.5 - 30.5% to 9.5 - 10.5%, the volume fraction of phase B is 4.5 - 5.5%, and the balance is phase C; during the period from 7 to 8 minutes, the volume fraction of phase A is 9.5 - 10.5%, the volume fraction of phase B increases from 4.5 - 5.5% to 14.5 - 15.5%, and the balance is phase C; during the period from 8 to 9 minutes, the volume fraction of phase A is 9.5 - 10.5%, the volume fraction of phase B increases from 14.5 - 15.5% to 29.5 - 30.5%, and the balance is phase C; during the period from 9 to 13 minutes, the volume fraction of phase A is maintained at 9.5 - 10.5%, the volume fraction of phase B is maintained at 29.5 - 30.5%, and the balance is phase C; during the period from 13 to 13.1 minutes, the volume fraction of phase A increases from 9.5 - 10.5% to 29.5 - 30.5%, the volume fraction of phase B decreases from 29.5 - 30.5% to 4.5 - 5.5%, and the balance is phase C; during the period from 13.1 to 20 minutes, the volume fraction of phase A is 29.5 - 30.5%, the volume fraction of phase B is 4.5 - 5.5%, and the balance is phase C; within each time period, the total volume of phase A, phase B, and phase C is 100%.

[0021] In some embodiments, the volume fraction of heptafluorobutyric acid in phase A is 0.39 - 0.41%. Through experiments, using this eluent for gradient elution gives better detection results.

[0022] In some embodiments, the volume fraction of acetonitrile in phase B is 49 - 51%. Through experiments, using this eluent for gradient elution gives better detection results.

[0023] In some embodiments, the flow rate of the gradient elution is 0.9 - 1.1 mL / min.

[0024] In some embodiments, the suppressor adopts an external water addition mode, and the suppression current is 101 - 105 mA.

[0025] In some embodiments, the column temperature of the chromatographic column is 29 - 31 °C.

[0026] In some embodiments, the temperature of the detector is 34 - 36 °C.

[0027] In some embodiments, the injection volume for ion chromatography analysis is 20 - 30 μL.

[0028] In some embodiments, ion chromatography analysis is performed on at least three different concentrations of 2,3 - dihydroxypropyl - trimethyl ammonium chloride standard solutions to obtain a standard curve of ion concentration vs. peak area. Using the peak area of the sample to be detected and the standard curve, the concentration of 2,3 - dihydroxypropyl - trimethyl ammonium chloride in the sample to be detected is calculated.

[0029] Another embodiment of the present invention provides an application of the detection method of 2,3 - dihydroxypropyl - trimethyl ammonium chloride in the above - mentioned cationic modifier in the quality control of the production process of the cationic modifier.

[0030] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with specific embodiments.

[0031] Example 1

[0032] Preparation process of the standard curve:

[0033] Accurately weigh an appropriate amount of 2,3 - dihydroxypropyl - trimethyl ammonium chloride reference substance, place it in a 100 mL volumetric flask, add 0.1% heptafluorobutyric acid solution to the scale, shake well, and dilute to a final concentration of 128 μg / mL as the stock solution; accurately pipette an appropriate amount of the above stock solution and dilute it with 0.1% heptafluorobutyric acid solution to prepare a series of standard solutions with concentrations of 32 μg / mL, 3.2 μg / mL, 1.6 μg / mL, and 0.32 μg / mL. Through ion chromatography analysis and detection of each standard solution, an ion chromatography standard map of 2,3 - dihydroxypropyl - trimethyl ammonium chloride is obtained, and a unary linear regression equation is drawn: y = 0.0560x - 0.0111, R 2 = 0.9998; y is the peak area, x is the ion concentration, and the units are μS*min and μg / mL respectively; a standard curve is drawn with the concentration of the 2,3 - dihydroxypropyl - trimethyl ammonium chloride standard solution as the abscissa and its corresponding peak area as the ordinate as Figure 1 shown.

[0034] Pretreatment process of the sample:

[0035] The sample was diluted with 0.1% heptafluorobutyric acid solution to prepare a test sample diluted 100 times.

[0036] Detection process:

[0037] A Thermo ICS-5000+ ion chromatograph (dual system) was used. The sample injection volume was 25 μL. The chromatographic column was Waters XBridge C18 5 μm 4.6*250 mm. The column temperature of the chromatographic column was 30 °C. The detector type was a conductivity detector. The cell temperature of the conductivity detector was 35 °C. The suppressor was a Dionex CSRS 300 4 mm cation suppressor. The external water addition mode was adopted. The suppression current was 103 mA. The eluents were A (0.4% heptafluorobutyric acid), B (50% acetonitrile solution), and C (ultrapure water). Gradient elution was performed at a flow rate of 1.0 mL / min. The gradient elution conditions are shown in Table 1.

[0038] Table 1 Gradient elution conditions

[0039]

[0040]

[0041] After detection, the detection limit of this method was 0.1 μg / mL, and it had a good linear relationship in the concentration range of 0.32 - 32 μg / mL.

[0042] Detection results:

[0043] Three different samples were taken, diluted 100 times with 0.1% heptafluorobutyric acid solution and then injected for analysis. The results are shown in Table 2.

[0044] Table 2 Sample content

[0045]

[0046] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier, characterized in that, A cationic modifier containing 2,3-dihydroxypropyl-trimethylammonium chloride is diluted with a 0.05 - 0.15% heptafluorobutyric acid solution by volume to obtain a sample to be tested, and the sample to be tested is analyzed by ion chromatography; During the ion chromatography analysis, the chromatographic column is a C18 reversed-phase chromatographic column, the detector is a conductivity detector, and the suppressor is a cation suppressor; in the eluent, a 0.35 - 0.45% heptafluorobutyric acid solution by volume is used as phase A, a 45 - 55% acetonitrile solution by volume is used as phase B, and ultrapure water is used as phase C; The gradient elution conditions are as follows: during the period of 0 - 5 min, the volume fraction of phase A is 29.5 - 30.5%, the volume fraction of phase B is 4.5 - 5.5%, and the balance is phase C; during the period of 5 - 7 min, the volume fraction of phase A decreases from 29.5 - 30.5% to 9.5 - 10.5%, the volume fraction of phase B is 4.5 - 5.5%, and the balance is phase C; during the period of 7 - 8 min, the volume fraction of phase A is 9.5 - 10.5%, the volume fraction of phase B increases from 4.5 - 5.5% to 14.5 - 15.5%, and the balance is phase C; during the period of 8 - 9 min, the volume fraction of phase A is 9.5 - 10.5%, the volume fraction of phase B increases from 14.5 - 15.5% to 29.5 - 30.5%, and the balance is phase C; during the period of 9 - 13 min, the volume fraction of phase A is maintained at 9.5 - 10.5%, the volume fraction of phase B is maintained at 29.5 - 30.5%, and the balance is phase C; During the period of 13 - 13.1 min, the volume fraction of phase A increases from 9.5 - 10.5% to 29.5 - 30.5%, the volume fraction of phase B decreases from 29.5 - 30.5% to 4.5 - 5.5%, and the balance is phase C; during the period of 13.1 - 20 min, the volume fraction of phase A is 29.5 - 30.5%, the volume fraction of phase B is 4.5 - 5.5%, and the balance is phase C; within each time period, the total volume of phase A, phase B, and phase C is 100%.

2. The detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to claim 1, characterized in that, The volume fraction of heptafluorobutyric acid in phase A is 0.39 - 0.41%.

3. The detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to claim 1, characterized in that, The volume fraction of acetonitrile in phase B is 49 - 51%.

4. The detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to claim 1, characterized in that, The flow rate of gradient elution is 0.9 - 1.1 mL / min.

5. The detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to claim 1, characterized in that, The suppressor adopts the external water addition mode, and the suppression current is 101 - 105 mA.

6. The detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to claim 1, characterized in that, The column temperature of the chromatographic column is 29 - 31 °C.

7. The detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to claim 1, characterized in that, The temperature of the detector is 34 - 36 °C.

8. The detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to claim 1, characterized in that, The injection volume for ion chromatography analysis is 20 - 30 μL.

9. The detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to claim 1, characterized in that, Ion chromatography analysis is performed on at least three different concentrations of 2,3-dihydroxypropyl-trimethylammonium chloride standard solutions to obtain a standard curve of ion concentration vs. peak area. Using the peak area of the sample to be tested and the standard curve, the concentration of 2,3-dihydroxypropyl-trimethylammonium chloride in the sample to be tested is calculated.

10. Application of the detection method for 2,3-dihydroxypropyl-trimethyl ammonium chloride in a cationic modifier according to any one of claims 1 to 9 in quality monitoring of the production process of the cationic modifier.

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