阅读说明：本技术 一种4-甲基-n-苯基苯胺及邻氯苯甲酸杂质的检测方法 (Method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid ) 是由 汪游清 韩学哲 肖楚晖 申丽坤 于 2020-11-12 设计创作，主要内容包括：本发明属于4-甲基-N-苯基苯胺及邻氯苯甲酸杂质的检测领域,具体涉及一种4-甲基-N-苯基苯胺及邻氯苯甲酸杂质的检测方法。该检测方法包括以下步骤：1)将标准溶液在设定的色谱条件下进行高效液相色谱分析,得到线性回归方程；2)将样品溶液在设定的色谱条件下进行高效液相色谱分析,并根据线性回归方程计算得到4-甲基-N-苯基苯胺和邻氯苯甲酸的含量。该检测方法中,通过色谱分析条件的设定,使得主成分4-甲基-N-苯基苯胺和杂质成分邻氯苯甲酸得到良好分离和定量,避免了气相色谱法检测邻氯苯甲酸的复杂前处理,检测结果准确可靠,为产品的质量控制提供了保证。(The invention belongs to the field of detection of impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid, and particularly relates to a method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid. The detection method comprises the following steps: 1) performing high performance liquid chromatography analysis on the standard solution under a set chromatographic condition to obtain a linear regression equation; 2) and (3) carrying out high performance liquid chromatography analysis on the sample solution under a set chromatographic condition, and calculating the contents of the 4-methyl-N-phenylaniline and the o-chlorobenzoic acid according to a linear regression equation. In the detection method, the 4-methyl-N-phenylamine serving as the main component and the o-chlorobenzoic acid serving as the impurity component are well separated and quantified by setting chromatographic analysis conditions, so that the complex pretreatment of detecting the o-chlorobenzoic acid by using a gas chromatography is avoided, the detection result is accurate and reliable, and the quality control of the product is guaranteed.)

1. The method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid is characterized by comprising the following steps:

1) preparing a standard solution from a 4-methyl-N-phenylaniline standard substance, an o-chlorobenzoic acid standard substance and a solvent, and performing high performance liquid chromatography analysis on the standard solution to obtain a linear regression equation;

2) preparing a sample solution from a to-be-detected 4-methyl-N-phenylaniline sample and a solvent, carrying out high performance liquid chromatography analysis on the sample solution, and calculating according to the linear regression equation determined in the step 1) to obtain the contents of 4-methyl-N-phenylaniline and o-chlorobenzoic acid;

the chromatographic conditions of the high performance liquid chromatography are as follows:

a chromatographic column: kromasil 100-5-C18;

mobile phase: the mobile phase A is water, the mobile phase B is composed of phosphoric acid and methanol, and the pH value is 2.0-3.0; the volume ratio of the mobile phase A to the mobile phase B is 50-25: 50-75;

and (3) an elution mode: gradient elution.

2. The method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid as claimed in claim 1, wherein in the step 2), the concentration of the sample solution is 1.2-2.4 g/L.

3. The method of claim 1, wherein the mobile phase B has a pH of 2.7.

4. The method of claim 1, wherein the high performance liquid chromatography comprises the following steps: 1.0 mL/min; detection wavelength: 200-220 nm; column temperature: 20-30 ℃; sample introduction amount: 10-20 μ L.

5. The method of detecting 4-methyl-N-phenylaniline and o-chlorobenzoic acid impurities as claimed in any one of claims 1 to 4 wherein the gradient elution conditions are:

when the sample introduction time is 0min, the volume percentage of the A mobile phase is 50 percent, and the volume percentage of the B mobile phase is 50 percent;

when the sample introduction time is 20min, the volume percentage of the A mobile phase is decreased to 25 percent, and the volume percentage of the B mobile phase is 75 percent;

when the sample injection time is 40min, the volume percentage of the A mobile phase is 25%, and the volume percentage of the B mobile phase is 75%.

6. The method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid as claimed in claim 5, wherein in the step 1), the standard solution comprises a 4-methyl-N-phenylaniline standard solution and an o-chlorobenzoic acid standard solution, the concentration of the 4-methyl-N-phenylaniline standard solution is 1.2-2.8mg/mL, and the concentration of the o-chlorobenzoic acid standard solution is 30-70 μ g/mL.

Technical Field

The invention belongs to the field of detection of impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid, and particularly relates to a method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid.

Background

4-methyl-N-phenylaniline is an important raw material for synthesizing N, N ' -diphenyl-N, N ' -di (4-methylphenyl) 4, 4 ' -biphenyldiamine (p-TPD for short), and the p-TPD is a photoelectric hole transport material and has wide application in the field of semiconductors.

A common synthetic route for 4-methyl-N-phenylaniline is as follows:

hole transport materials are materials in which some groups lose electrons to form cationic groups, and neutral molecules transfer electrons to the cations, thereby completing the oxidation-reduction process. Therefore, the neutral molecule of the hole transport material must be a good electron donor. O-chlorobenzoic acid is taken as an impurity of 4-methyl-N-phenyl aniline, is an electron-withdrawing body, and can be brought into p-TPD to influence the product purity, so that the photoconductivity is influenced, and the imaging is unclear.

Therefore, the method can accurately quantify the impurities of the 4-methyl-N-phenylaniline and the o-chlorobenzoic acid, and has important significance for controlling the quality of products.

In the prior report, 4-methyl-N-phenylaniline can be quantitatively detected using gas chromatography (Euro.J.org.chem.,2014, 2070-2076). However, since o-chlorobenzoic acid is unstable at high temperatures, it requires a complicated pretreatment for gas chromatography, and this pretreatment may affect 4-methyl-N-phenylaniline. Therefore, the existing gas chromatography cannot accurately quantify the impurities of the 4-methyl-N-phenylaniline and the o-chlorobenzoic acid.

Disclosure of Invention

The invention aims to provide a method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid, which can realize accurate quantification of main components and the impurities of the o-chlorobenzoic acid.

In order to realize the purpose, the technical scheme of the method for detecting the impurities of the 4-methyl-N-phenylaniline and the o-chlorobenzoic acid is as follows:

a method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid comprises the following steps:

1) preparing a standard solution from a 4-methyl-N-phenylaniline standard substance, an o-chlorobenzoic acid standard substance and a solvent, and performing high performance liquid chromatography analysis on the standard solution to obtain a linear regression equation;

2) preparing a sample solution from a to-be-detected 4-methyl-N-phenylaniline sample and a solvent, carrying out high performance liquid chromatography analysis on the sample solution, and calculating according to the linear regression equation determined in the step 1) to obtain the contents of 4-methyl-N-phenylaniline and o-chlorobenzoic acid;

the chromatographic conditions of the high performance liquid chromatography are as follows:

a chromatographic column: kromasil 100-5-C18;

mobile phase: the mobile phase A is water, the mobile phase B is composed of phosphoric acid and methanol, and the pH value is 2.0-3.0; the volume ratio of the mobile phase A to the mobile phase B is 50-25: 50-75;

and (3) an elution mode: gradient elution.

According to the method for detecting the 4-methyl-N-phenylaniline and the o-chlorobenzoic acid impurities, the 4-methyl-N-phenylaniline serving as the main component and the o-chlorobenzoic acid serving as the impurity component are well separated and quantified by setting the chromatographic analysis conditions, so that the complex pretreatment of detecting the o-chlorobenzoic acid by using a gas chromatography is avoided, the detection result is accurate and reliable, and the guarantee is provided for the quality control of the product.

In order to measure the main components and the impurity content of the sample, the concentration of the sample needs to be large enough to ensure that the impurity can generate a peak when the impurity content is measured; when the content of the main component is measured, the chromatographic peak is beyond the detection range and cannot be quantified due to overlarge concentration, and in order to further improve the detection accuracy, the concentration of the sample solution in the step 2) is preferably 1.2-2.4 g/L.

The solvent of the 4-methyl-N-phenylaniline standard solution, the o-chlorobenzoic acid standard solution and the 4-methyl-N-phenylaniline sample solution is methanol, and preferably, the pH of the mobile phase B is 2.7.

Flow rate during high performance liquid chromatography analysis: 1.0 mL/min; detection wavelength: 200-220 nm; column temperature: 20-30 ℃; sample introduction amount: 10-20 μ L. By adopting the chromatographic analysis conditions, the detection of the main component content of 99.92 percent and the o-chlorobenzoic acid content of 0.02 percent can be realized, the precision is not more than 1.03 percent, the accuracy is extremely high, and the simple, convenient and reliable analysis detection method is provided for the quality control in the production process of the 4-methyl-N-phenylaniline.

The gradient elution conditions were:

when the sample introduction time is 0min, the volume percentage of the A mobile phase is 50 percent, and the volume percentage of the B mobile phase is 50 percent;

when the sample introduction time is 20min, the volume percentage of the A mobile phase is decreased to 25 percent, and the volume percentage of the B mobile phase is 75 percent;

when the sample injection time is 40min, the volume percentage of the A mobile phase is 25%, and the volume percentage of the B mobile phase is 75%.

In the step 1), a 4-methyl-N-phenylaniline standard solution and an o-chlorobenzoic acid standard solution can be prepared respectively, or a mixed standard solution can be prepared. Preferably, the standard solution comprises a 4-methyl-N-phenylaniline standard solution and an o-chlorobenzoic acid standard solution, the concentration of the 4-methyl-N-phenylaniline standard solution is 1.2-2.8mg/mL, and the concentration of the o-chlorobenzoic acid standard solution is 30-70 mu g/mL. Respectively injecting the 4-methyl-N-phenylaniline and the o-chlorobenzoic acid standard solution into a high performance liquid chromatograph, carrying out chromatographic analysis according to set chromatographic conditions, recording corresponding peak areas, and constructing a mass concentration-peak area standard curve to obtain two linear regression equations.

The concentration of the 4-methyl-N-phenylaniline standard solution is 1.2-2.8 mg/mL. For example, the test can be performed with a series of standard solutions configured to 1.2mg/mL, 1.6mg/mL, 2.0mg/mL, 2.4mg/mL, 2.8 mg/mL.

The concentration of the o-chlorobenzoic acid standard solution is 30-70 mug/mL. For example, a series of standard solutions configured to 30.00. mu.g/mL, 40.00. mu.g/mL, 50.00. mu.g/mL, 60.00. mu.g/mL, 70.00. mu.g/mL can be tested.

Drawings

FIG. 1 is a graph showing a standard curve of 4-methyl-phenylaniline in an example of the present invention;

FIG. 2 is a graph showing a standard curve of o-chlorobenzoic acid in the examples of the present invention;

FIG. 3 is a graph showing the separation effect of comparative example 1 using 100% methanol as a mobile phase;

FIG. 4 is a graph showing the separation effect of comparative example 2 using 90% methanol and 10% water as mobile phases;

FIG. 5 is a graph showing the separation effect of comparative example 3 with 75% methanol and 25% water as mobile phases;

FIG. 6 is a chromatogram of a sample of an example of the present invention, in which peak a is o-chlorobenzoic acid and peak b is 4-methyl-N-phenylaniline;

FIG. 7 is a UV spectrum of 4-methyl-N-phenylaniline;

FIG. 8 is a UV spectrum of o-chlorobenzoic acid.

Detailed Description

The following examples are provided to further illustrate the practice of the invention.

First, the specific embodiment of the method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid

Example 1

The method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid in the embodiment comprises the following steps:

1) preparing a 4-methyl-N-phenylaniline standard solution: respectively and accurately weighing 30mg, 40mg, 50mg, 60mg and 70mg of 4-methyl-N-phenylaniline standard samples in 25mL volumetric flasks, uniformly mixing the samples with methanol, ultrasonically degassing for later use, cooling to room temperature, and fixing the volume to scale to obtain standard solutions I, II, III, IV and V with the concentrations of 1.2mg/mL, 1.6mg/mL, 2.0mg/mL, 2.4mg/mL and 2.8 mg/mL.

2) Preparing an o-chlorobenzoic acid standard solution: accurately weighing 0.75mg, 1.00mg, 1.25mg, 1.50mg and 1.75mg of o-chlorobenzoic acid standard samples in a 25mL volumetric flask, uniformly mixing with methanol, ultrasonically degassing for later use, cooling to room temperature, and fixing the volume to scale to obtain standard solutions I, II, III, IV and V with the concentrations of 30.00 mu g/mL, 40.00 mu g/mL, 50.00 mu g/mL, 60.00 mu g/mL and 70.00 mu g/mL respectively.

3) Respectively injecting the 4-methyl-N-phenylaniline and the o-chlorobenzoic acid standard solution into a high performance liquid chromatograph, carrying out chromatographic analysis according to set chromatographic conditions, recording corresponding peak areas, and constructing a mass concentration-peak area standard curve to obtain two linear regression equations (shown in figures 1 and 2);

the chromatographic conditions were as follows:

a chromatographic column: kromasil 100-5-C18 with specification of 5 μm 4.6mm 250mm

Mobile phase: the mobile phase A is water, the mobile phase B is chromatographic methanol, and the pH of the mobile phase B is adjusted to 2.7 by phosphoric acid. The volume ratio of the A mobile phase to the B mobile phase is 50: 50. filtering the mobile phase water and the methanol by a filter membrane and ultrasonically degassing for later use.

And (3) an elution mode: gradient elution

Flow rate: 1.0 mL/min.

Detection wavelength: 210 nm.

Column temperature: at 30 ℃.

Sample introduction amount: 15 μ L.

The gradient elution conditions were:

when the sample introduction time is 0min, the volume percentage of the A mobile phase is 50 percent, and the volume percentage of the B mobile phase is 50 percent;

when the sample introduction time is 20min, the volume percentage of the A mobile phase is uniformly reduced to 25%, and the volume percentage of the B mobile phase is 75%;

when the sample injection time is 40min, the volume percentage of the A mobile phase is 25%, and the volume percentage of the B mobile phase is 75%.

The peak area is plotted against the concentration, the concentration of the 4-methyl-N-phenylaniline is in the range of 1.0-3.0mg/mL, the concentration of the o-chlorobenzoic acid is in the range of 25-75 mu g/mL, the sample concentration and the peak area have a linear relation, and the linear regression equations of the two are respectively as follows: a. the_{4-methyl-N-phenylaniline}＝44726x+21.828，R²＝0.9998；A_{O-chlorobenzoic acid}＝46.645x+21.828，R²＝0.9999。

4) Accurately weighing 50mg of sample to be detected of batch No. 1 in a 25mL volumetric flask, uniformly mixing the sample with methanol, ultrasonically degassing for later use, cooling to room temperature, and fixing the volume to a scale to obtain a sample solution with the concentration of 2.0 mg/mL;

injecting the sample solution to be detected into a high performance liquid chromatograph, and carrying out chromatographic analysis according to set chromatographic conditions. And recording corresponding peak areas and substituting the peak areas into a linear regression equation to calculate the content of the 4-methyl-N-phenylaniline and the o-chlorobenzoic acid.

Examples 2 to 5

The samples to be tested of batches 2 to 5 were tested by the method of example 1.

In other examples of the method for detecting 4-methyl-N-phenylaniline and o-chlorobenzoic acid impurities of the present invention, the difference from example 1 is that the mobile phase B has pH values of 2.0, 2.3, 2.5 and 3.0, respectively, and the detection results equivalent to or slightly inferior to those of example 1 can be obtained. In step 4), the amounts of the samples may be 30, 40, 55mg, and 60mg, respectively, and the results of the tests comparable to those in the examples can be obtained.

Second, comparative example

Comparative example 1

The method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid in comparative example 1 was different from that described in example 1 in that the mobile phase was methanol.

Comparative example 2

The method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid in comparative example 2 is different from that described in example 1 in that the mobile phase A is water, the mobile phase B is methanol, the volume ratio of the mobile phase A to the mobile phase B is 10:90, and isocratic elution is adopted.

Comparative example 3

The method for detecting impurities of 4-methyl-N-phenylaniline and o-chlorobenzoic acid in comparative example 3 is different from that described in example 1 in that the mobile phase A is water, the mobile phase B is methanol, the volume ratio of the mobile phase A to the mobile phase B is 25:75, and isocratic elution is adopted.

Third, Experimental example

Experimental example 1

Chromatograms of comparative example 1, comparative example 2, comparative example 3, and example 1 are shown in fig. 3 to 6.

The 4-methyl-N-phenylaniline and the o-chlorobenzoic acid have better dissolving effect in the methanol, so the methanol is used as the organic phase of the mobile phase. However, when methanol alone was used as the mobile phase, the separation was poor (FIG. 3). Comparative examples 2 to 3, in which methanol-water solutions of different volume ratios were used as mobile phases, improved the separation effect to some extent, but the peak shape was poor and there was a tailing effect. In the 4-methyl-N-phenylaniline sample, the content difference of the main component and the impurity is very different, the high performance liquid chromatography is used for carrying out accurate quantification on the main component and the impurity at the same time, and the separation degree of the comparative examples 2-3 can influence the quantification of the main component and the impurity, thereby being not beneficial to improving the accuracy of the quantification.

The method of example 1 provides the best separation, and can enhance the separation of components and the symmetry of peaks by tailing off effects.

Experimental example 2

The ultraviolet spectrum of 4-methyl-N-phenylaniline is shown in FIG. 7 and the ultraviolet spectrum of o-chlorobenzoic acid is shown in FIG. 8 by using a diode array detector to perform continuous scanning at 190-400 nm.

As can be seen from the figure, 4-methyl-N-phenylaniline and o-chlorobenzoic acid both have the maximum absorption at 210nm, so the detection wavelength is selected to be 210 nm.

Experimental example 3 repeatability experiment

Accurately weighing 6 parts of sample to be measured, respectively placing the sample to be measured in 25mL volumetric flasks, adding methanol to dissolve the sample, ultrasonically degassing the sample for later use, cooling the sample to room temperature, and fixing the volume to a scale to obtain a sample solution with the concentration of 2.0 mg/mL; the content of 4-methyl-N-phenylaniline was measured according to the method of the present invention in example 1, and the results are shown in Table 1:

TABLE 1 results of the repeatability tests

As can be seen from Table 1, the RSD% of the reproducibility was 0.07, which was satisfactory.

EXAMPLE 4 precision test

Accurately weighing 50mg of a sample to be detected, placing the sample to be detected in a 25mL volumetric flask, adding methanol for dissolution, ultrasonically degassing for later use, cooling to room temperature, and fixing the volume to a scale to obtain a sample solution with the concentration of 2.0 mg/mL; according to the chromatographic conditions in the embodiment 1 of the invention, the solution was sampled 6 times, the peak area was recorded, the precision of the sample injection was calculated, and the results are listed in table 2:

TABLE 2 results of precision test

As can be seen from Table 2, the RSD% of the injection precision was 0.79, which meets the requirement.

In examples 1 to 5, the results of examining 4-methyl-N-phenylaniline as a main component and o-chlorobenzoic acid as an impurity in 5 lots are shown in Table 3.

TABLE 3 test results

As can be seen from Table 3, the method of the present invention can achieve simultaneous detection of the main component 4-methyl-N-phenylaniline and the impurity o-chlorobenzoic acid, and RSD (%) is not more than 1.03, and the method has the advantages of simple and convenient sample treatment and high accuracy, and provides a simple and reliable analysis and detection method for quality control in the production process of 4-methyl-N-phenylaniline.