A method for detecting terephthalonitrile or isophthalonitrile content and its application

Abstract

The present invention relates to a method for detecting the content of terephthalonitrile or isophthalonitrile and its application. The method for detecting the content of terephthalonitrile or isophthalonitrile comprises the following steps: gas chromatography detection is performed on a standard sample solution and a sample solution prepared with an internal standard substance, respectively, and the content of the analyte is calculated according to the detection result, wherein the analyte comprises terephthalonitrile or isophthalonitrile. Among them, the present invention creatively uses naphthalene as an internal standard substance, which is conducive to the rapid detection and accurate quantification of terephthalonitrile or isophthalonitrile. The detection method of the present invention has fast analysis speed, good separation effect, good repeatability, high accuracy, simplicity and economy, and has important application value in pesticide detection or medical detection.

Description

Technical Field

[0001] The invention belongs to the field of analytical chemistry, and specifically relates to a gas chromatography detection method for terephthalonitrile or isophthalonitrile content and an application thereof, and in particular to a rapid and accurate gas chromatography detection method for terephthalonitrile or isophthalonitrile content and an application thereof. Background Art

[0002] Terephthalonitrile, white needle-shaped crystals or powder, is insoluble in water, slightly soluble in ethanol, acetone and hot ether, and soluble in hot benzene and hot acetic acid. Terephthalonitrile is an important organic intermediate that can synthesize a series of fine chemical products and is widely used in the fields of pesticides, medicines, dyes, fragrances, and resins. The p-phenylenediamine obtained by hydrogenation of terephthalonitrile is an important raw material for polyamide and an excellent epoxy resin curing agent; the tetrachloroterephthalonitrile obtained by its reaction with chlorine can be used to synthesize the herbicide chlorphthalic acid, pyrethroid insecticides, and drugs for treating cerebral thrombosis; the terephthalic acid obtained by its hydrolysis can be used to produce polyester resins, polyester fibers, films, insulating paints, engineering plastics, and plasticizers. Isophthalonitrile, white needle-shaped crystals or powder, is soluble in benzene, ether, hot ethanol and chloroform, and slightly soluble in water. Isophthalonitrile is also an important organic intermediate. Its meta-xylylenediamine obtained by hydrogenation reaction is an epoxy resin curing agent with excellent performance and can also be used as other fine chemical raw materials. Its pesticide chlorothalonil obtained by chlorination reaction has the advantages of high efficiency, broad spectrum, low toxicity and low residue. Because of the wide application of terephthalonitrile and isophthalonitrile, the demand for high-quality terephthalonitrile and isophthalonitrile in the domestic and foreign markets has also increased year by year in recent years. The simple, fast and accurate content detection method is of great significance for improving the quality of terephthalonitrile and isophthalonitrile products, promoting market trade and the efficient and high-quality production of downstream pharmaceuticals, pesticides and other products.

[0003] At present, there is no national or industry standard method for the detection of terephthalonitrile or isophthalonitrile content, and there are few related reports in domestic and foreign journals. The most commonly used methods for manufacturers and users are liquid chromatography and gas chromatography area percentage method. Among them, when using liquid chromatography for detection, there are the following shortcomings: First, since the liquid phase ultraviolet detector is suitable for detecting low-concentration solutions, when determining the content of the main component, the sample needs to be diluted and fixed to prepare a test solution with a suitable concentration, which is troublesome to operate and requires a large amount of organic solvent; secondly, terephthalonitrile and isophthalonitrile are a pair of isomers, which are difficult to separate from each other. In order to better separate the two, harmful reagents such as acetonitrile and methanol are required as mobile phases. The amount of organic reagents used is large, which is harmful to the environment and takes a long time to analyze; in addition, when using the liquid chromatography area percentage method for quantification, there are many impurity components in the sample, and the response values ​​of each component at the same wavelength will be very different, so the quantitative result has a large error. However, there are currently the following shortcomings when using gas chromatography for detection: first, due to the unsatisfactory selection of chromatographic columns and chromatographic separation conditions, it is difficult to completely separate isophthalonitrile and terephthalonitrile, which affects the accuracy of quantification; second, there are components in the sample that are not detected by gas chromatography, and the response values ​​of the impurity components vary greatly, resulting in large quantitative errors in the area percentage method; in addition, a few studies use the internal standard method for quantification, but because the selection of the internal standard is not very ideal, the detection time is long, and the sample is interfered with to varying degrees by the impurity components, resulting in poor detection repeatability.

[0004] Therefore, how to provide a method for detecting the content of terephthalonitrile or isophthalonitrile with good separation effect, good repeatability, high quantitative accuracy, fast detection speed, simplicity and economy has become an urgent problem to be solved in this field. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a method for detecting the content of terephthalonitrile or isophthalonitrile and its application. The detection method has fast analysis speed, good separation effect, good repeatability, high accuracy, simplicity and economy, and has important application value in pesticide detection or medicine detection.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for detecting the content of terephthalonitrile or isophthalonitrile, the detection method comprising the following steps: subjecting a standard sample solution and a sample solution prepared with an internal standard substance and a standard sample of the object to be detected to gas chromatography detection, and calculating the content of the object to be detected according to the detection result.

[0008] The analyte includes terephthalonitrile or isophthalonitrile.

[0009] The internal standard includes naphthalene.

[0010] The present invention provides a gas chromatography internal standard quantitative method, which can be used for the detection of terephthalonitrile content and can also be applied to the detection of isophthalonitrile content. Wherein, the present invention creatively uses naphthalene as an internal standard, and compared with other internal standards, naphthalene and terephthalonitrile or isophthalonitrile all have an ideal separation degree on the one hand, and in gas chromatography detection, naphthalene peaks in front of terephthalonitrile or isophthalonitrile and is not disturbed by any impurities in the sample, which is conducive to the rapid detection and accurate quantification of terephthalonitrile or isophthalonitrile. More importantly, since naphthalene peaks in front of terephthalonitrile or isophthalonitrile, the present invention only needs 9min to complete detection, and using acetophenone, diethyl phthalate, etc. commonly used in the prior art as internal standards requires more than 20min. In a word, the detection method provided by the present invention greatly shortens the gas chromatography analysis time, and the analysis speed is fast, and the precision and accuracy of the detection are higher, and can be applied to medical detection or pesticide detection.

[0011] Preferably, the method for preparing the standard solution and the sample solution comprises the following steps:

[0012] (1) dissolving and diluting the internal standard substance with a solvent, constant volume, to obtain an internal standard solution;

[0013] (2) dissolving a standard sample of the analyte with an internal standard solution to obtain the standard sample solution; and dissolving a sample of the analyte with an internal standard solution to obtain the sample solution.

[0014] Preferably, the solvent in step (1) comprises acetonitrile.

[0015] Compared with other solvents, acetonitrile has good solubility for internal standard naphthalene, terephthalonitrile and isophthalonitrile, and has a suitable boiling point. Using acetonitrile as a solvent is conducive to the stable existence of the prepared internal standard solution, standard solution and sample solution at room temperature, which helps to improve the accuracy of terephthalonitrile or isophthalonitrile content detection.

[0016] Preferably, the concentration of the internal standard solution in step (1) is 8-12 mg / mL.

[0017] Preferably, the concentration of the analyte standard in the standard solution of step (2) is 8-12 mg / mL.

[0018] Preferably, the concentration of the sample to be tested in the sample solution in step (2) is 8-12 mg / mL.

[0019] The specific point values ​​in the above 8-12 mg / mL can be selected as 8.0 mg / mL, 8.5 mg / mL, 9.0 mg / mL, 10 mg / mL, 10.5 mg / mL, 11.0 mg / mL, 11.5 mg / mL or 12 mg / mL, etc. Other specific point values ​​within this numerical range can be selected arbitrarily and will not be described one by one here.

[0020] The selection of the above-mentioned specific concentration range can make the concentration of the analyte in the standard solution consistent with that in the sample solution, and at the same time make the chromatographic response value of the analyte close to the response value of the internal standard, which can improve the accuracy of quantification. However, too low a solution concentration will lead to weighing errors, and too high a concentration will lead to difficulty in sample dissolution and poor solution stability, which will affect the accuracy of quantification and the stability of the method.

[0021] Preferably, the stationary phase of the chromatographic column in the gas chromatography detection is 50% phenyl-methylpolysiloxane, such as models DB-17, OV-17, HP-17, 007-17, SP-2250, RSL-300, etc. Other models of chromatographic columns with the same stationary phase can be selected and will not be described here one by one.

[0022] The selection of the stationary phase of the chromatographic column is the key to whether terephthalonitrile and isophthalonitrile can be effectively separated. Compared with other stationary phases, the above-mentioned specific chromatographic column stationary phase can shorten the analysis time while effectively separating terephthalonitrile and isophthalonitrile.

[0023] Preferably, the column temperature change process in the gas chromatography detection is as follows: the initial column temperature is 160-175°C, the initial column temperature is maintained for 4-6 minutes, the temperature is increased at a heating rate of 30-40°C / min to a final column temperature of 250-260°C, and the final column temperature is maintained for 3-5 minutes.

[0024] The specific values ​​of 160-175°C mentioned above include 160°C, 161°C, 162°C, 163°C, 164°C, 165°C, 166°C, 167°C, 168°C, 169°C, 170°C, 171°C, 172°C, 173°C, 174°C, 175°C, etc.

[0025] The specific values ​​of 4-6 min mentioned above include 4 min, 4.2 min, 4.5 min, 4.7 min, 5 min, 5.2 min, 5.5 min, 5.7 min, 6 min, etc.

[0026] The specific values ​​of 30-40°C / min mentioned above can be selected from 30°C / min, 31°C / min, 32°C / min, 33°C / min, 34°C / min, 35°C / min, 36°C / min, 37°C / min, 38°C / min, 39°C / min, 40°C / min, etc.

[0027] The specific values ​​of 250-260°C mentioned above can be selected as 250°C, 251°C, 252°C, 253°C, 254°C, 255°C, 256°C, 257°C, 258°C, 259°C, 260°C, etc.

[0028] The specific values ​​of 3-5min mentioned above can be 3min, 3.2min, 3.5min, 3.7min, 4min, 4.2min, 4.5min, 4.7min, 5min, etc.

[0029] Other specific point values ​​within the above numerical ranges can be selected and will not be described in detail here.

[0030] Preferably, the carrier gas in the gas chromatography detection includes nitrogen.

[0031] Preferably, the flow rate of the carrier gas is 1.5-3.5 mL / min, for example, 1.5 mL / min, 1.7 mL / min, 2.0 mL / min, 2.2 mL / min, 2.5 mL / min, 2.7 mL / min, 3.0 mL / min, 3.2 mL / min, 3.5 mL / min, etc. Other specific point values ​​within this numerical range can be selected and will not be described here one by one.

[0032] The combination of the above column temperature variation process and specific parameters in the carrier gas flow rate can make the gas chromatographic peak shape good, the separation effect good, the result more accurate and the detection speed fast.

[0033] Preferably, the temperature of the vaporization chamber in the gas chromatography detection is 260-300°C, for example, 260°C, 262°C, 265°C, 267°C, 270°C, 272°C, 275°C, 277°C, 280°C, 282°C, 285°C, 287°C, 290°C, 292°C, 295°C, 297°C, 300°C, etc. Other specific point values ​​within this numerical range can be selected, and they will not be described one by one here.

[0034] Preferably, the detection chamber temperature in the gas chromatography detection is 280-300°C, for example, 280°C, 282°C, 285°C, 287°C, 290°C, 292°C, 295°C, 297°C, 300°C, etc. Other specific point values ​​within this numerical range can be selected and will not be described here one by one.

[0035] Preferably, the split ratio in the gas chromatography detection is 20:1-50:1, for example 20:1, 22:1, 25:1, 27:1, 30:1, 32:1, 35:1, 37:1, 40:1, 42:1, 45:1, 47:1, 50:1, etc. Other specific point values ​​within this numerical range can be selected and will not be described here one by one.

[0036] Preferably, the injection volume in the gas chromatography detection is 0.5-2.0 μL, for example, 0.5 μL, 0.6 μL, 0.7 μL, 0.8 μL, 0.9 μL, 1.0 μL, 1.1 μL, 1.2 μL, 1.3 μL, 1.4 μL, 1.5 μL, 1.6 μL, 1.7 μL, 1.8 μL, 1.9 μL, 2.0 μL, etc. Other specific point values ​​within this numerical range can be selected, which will not be described here one by one.

[0037] The combination of the above specific parameters can control the amount of sample entering the chromatographic column, making the detection more precise.

[0038] In a second aspect, the present invention provides an application of the method for detecting the content of terephthalonitrile or isophthalonitrile as described in the first aspect in pesticide detection or pharmaceutical detection.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention provides a gas chromatography internal standard quantitative method, which can be used for the detection of terephthalonitrile content and can also be applied to the detection of isophthalonitrile content. Wherein, the present invention creatively uses naphthalene as an internal standard, and compared with other internal standards, naphthalene and terephthalonitrile or isophthalonitrile all have an ideal separation degree on the one hand, and in gas chromatography detection, naphthalene peaks in front of terephthalonitrile or isophthalonitrile and is not disturbed by any impurities in the sample, which is conducive to the rapid detection and accurate quantification of terephthalonitrile or isophthalonitrile. More importantly, since naphthalene peaks in front of terephthalonitrile or isophthalonitrile, the present invention only needs 9min to complete detection, and using benzophenone, diethyl phthalate, etc. commonly used in the prior art as internal standards requires more than 20min. In a word, the detection method provided by the present invention greatly shortens the gas chromatography analysis time, and the analysis speed is fast, and the precision and accuracy of the detection are higher, and can be applied to medical detection or pesticide detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is the GC chart of the first standard sample solution in Example 1, wherein 1 is naphthalene and 2 is terephthalonitrile.

[0042] Figure 2 This is the GC chart of the first sample solution in Example 1, where 1 is naphthalene and 2 is terephthalonitrile.

[0043] Figure 3 This is the GC chart of the second sample solution in Example 1, where 1 is naphthalene and 2 is terephthalonitrile.

[0044] Figure 4 This is the GC chart of the second standard sample solution in Example 1, where 1 is naphthalene and 2 is terephthalonitrile.

[0045] Figure 5 This is the standard curve of terephthalonitrile.

[0046] Figure 6 This is the GC chart of the first standard sample solution in Example 6, where 1 is naphthalene and 2 is isophthalonitrile.

[0047] Figure 7 This is the GC chart of the first sample solution in Example 6, where 1 is naphthalene and 2 is isophthalonitrile.

[0048] Figure 8 This is the GC chart of the second sample solution in Example 6, where 1 is naphthalene and 2 is isophthalonitrile.

[0049] Fig. 9 This is the GC chart of the second standard sample solution in Example 6, where 1 is naphthalene and 2 is isophthalonitrile.

[0050] Fig.10 This is the standard curve of isophthalonitrile. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] The instruments used in the following examples and comparative examples are: gas chromatograph is Agilent GC 7890B, equipped with FID detector; injector: 10 μL; balance: METTLER TOLEDO, model ME204 / 02. The mass fraction of the terephthalonitrile standard product described in the examples and comparative examples is 99.3%, and the mass fraction of the isophthalonitrile standard product is 99.2%. The terephthalonitrile and isophthalonitrile samples are from Jiangsu Xinhe Agricultural Chemical Co., Ltd., and other materials and reagents can be obtained from commercial channels unless otherwise specified.

[0053] Example 1

[0054] The present embodiment provides a method for detecting the content of terephthalonitrile, and the method for detecting the content of terephthalonitrile comprises the following steps:

[0055] (1) Weigh 2.0 g (accurate to 0.0001 g) of naphthalene into a 250 mL volumetric flask, add an appropriate amount of acetonitrile to dissolve and dilute to scale, and shake well to obtain an internal standard solution.

[0056] (2) Weigh 0.10 g (accurate to 0.0001 g) of terephthalonitrile standard sample and place it in a stoppered glass bottle. Use a 10-mL pipette to add 10 mL of internal standard solution. Oscillate in an ultrasonic (40 kHz) environment for 10 min to completely dissolve it. Cool to room temperature and shake well to obtain a standard solution.

[0057] (3) Grind the terephthalonitrile sample into fine powder and mix well. Weigh 0.10 g (accurate to 0.0001 g) of the terephthalonitrile sample and place it in a stoppered glass bottle. Use a 10 mL pipette to add 10 mL of the internal standard solution. Oscillate in an ultrasonic environment for 10 min to completely dissolve it. Cool to room temperature and shake well to obtain a sample solution.

[0058] (4) The standard solution was injected into the gas chromatograph for detection until the relative change in the peak area of ​​two adjacent pairs of phthalonitrile and the internal standard was less than 1.0%, and then the standard solution, the sample solution, the sample solution, and the standard solution were measured in the order of the chromatographic conditions as follows:

[0059] The chromatographic column model is DB-17, the stationary phase is 50% phenyl-methylpolysiloxane, the column length is 30m, the inner diameter is 0.25mm, and the film thickness is 0.5μm; the temperature change process of the chromatographic column is as follows: the initial column temperature is 170℃ and maintained for 4min, and the temperature is increased to the final column temperature of 260℃ at a heating rate of 40℃ / min and maintained for 3min. The vaporization chamber temperature is 270℃, the detection chamber temperature is 300℃, the carrier gas is high-purity nitrogen, the flow rate is 2.0mL / min, the split ratio is 30:1, and the injection volume is 1.0μL.

[0060] Figure 1-4 These are the GC graphs of the first standard solution, the first sample solution, the second sample solution and the second standard solution, where 1 is naphthalene and 2 is terephthalonitrile.

[0061] Example 2

[0062] The present embodiment provides a method for detecting the content of terephthalonitrile, and the method for detecting the content of terephthalonitrile comprises the following steps:

[0063] (1) Weigh 3.0 g (accurate to 0.0001 g) of naphthalene into a 250 mL volumetric flask, add an appropriate amount of anhydrous acetonitrile to dissolve and dilute to scale, and shake well to obtain an internal standard solution.

[0064] (2) Weigh 0.12 g (accurate to 0.0001 g) of terephthalonitrile standard sample and place it in a stoppered glass bottle. Use a 10-mL pipette to add 10 mL of internal standard solution. Oscillate in an ultrasonic (frequency 40 kHz) for 10 min to completely dissolve it. Cool to room temperature and shake well to obtain a standard solution.

[0065] (3) Grind the terephthalonitrile sample into fine powder and mix well. Weigh 0.12 g (accurate to 0.0001 g) of the terephthalonitrile sample and place it in a stoppered glass bottle. Use a 10 mL pipette to add 10 mL of the internal standard solution. Oscillate in ultrasound (frequency 40 kHz) for 10 min to completely dissolve it. Cool to room temperature and shake well to obtain the sample solution.

[0066] (4) The standard solution was injected into the gas chromatograph for detection until the relative change in the peak area of ​​two adjacent pairs of phthalonitrile and the internal standard was less than 1.0%, and then the standard solution, the sample solution, the sample solution, and the standard solution were measured in the order of the chromatographic conditions as follows:

[0067] The chromatographic column model is 007-17, and its stationary phase is 50% phenyl-methylpolysiloxane; the temperature change process of the chromatographic column is as follows: the initial column temperature is 160°C and maintained for 5 minutes, and the temperature is increased to the final column temperature of 250°C at a heating rate of 40°C / min and maintained for 5 minutes. The vaporization chamber temperature is 260°C, the detection chamber temperature is 280°C, the carrier gas is high-purity nitrogen, the flow rate is 1.5mL / min, the split ratio is 20:1, and the injection volume is 1.0μL.

[0068] Example 3

[0069] The present embodiment provides a method for detecting the content of terephthalonitrile, and the method for detecting the content of terephthalonitrile comprises the following steps:

[0070] (1) Weigh 2.5 g of naphthalene (accurate to 0.0001 g) and place it in a 250 mL volumetric flask. Add an appropriate amount of acetonitrile to dissolve and dilute to the mark. Shake well to obtain an internal standard solution.

[0071] (2) Weigh 0.09 g (accurate to 0.0001 g) of terephthalonitrile standard sample and place it in a stoppered glass bottle. Use a 10-mL pipette to add 10 mL of internal standard solution. Oscillate in an ultrasonic (40 kHz) environment for 10 min to completely dissolve it. Cool to room temperature and shake well to obtain a standard solution.

[0072] (3) Grind the terephthalonitrile sample into fine powder and mix well. Weigh 0.09 g (accurate to 0.0001 g) of the terephthalonitrile sample and place it in a stoppered glass bottle. Use a 10 mL pipette to add 10 mL of the internal standard solution. Oscillate in an ultrasonic (40 kHz) for 10 min to completely dissolve it. Cool to room temperature and shake well.

[0073] (4) The standard solution was injected into the gas chromatograph for detection until the relative change in the peak area of ​​two adjacent pairs of phthalonitrile and the internal standard was less than 1.0%, and then the standard solution, the sample solution, the sample solution, and the standard solution were measured in the order of the chromatographic conditions as follows:

[0074] The chromatographic column model is OV-17, and its stationary phase is 50% phenyl-methylpolysiloxane; the temperature change process of the chromatographic column is as follows: the initial column temperature is 175°C and maintained for 4 minutes, and then the temperature is increased to the final column temperature of 255°C at a heating rate of 35°C / min and maintained for 4 minutes; the vaporization chamber temperature is 265°C, the detection chamber temperature is 290°C, the carrier gas is high-purity nitrogen, the flow rate is 2.5mL / min, the split ratio is 50:1, and the injection volume is 1.0μL.

[0075] Example 4

[0076] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that the chromatographic conditions are set as follows:

[0077] The temperature change process of the chromatographic column is as follows: the initial column temperature is 172°C, maintained for 5 minutes, and then increased to the final column temperature of 255°C at a heating rate of 32°C / min, and maintained for 4 minutes; the vaporization chamber temperature is 290°C, the detection chamber temperature is 300°C, the carrier gas is high-purity nitrogen, the flow rate is 2.5mL / min, the split ratio is 35:1, and the injection volume is 1.0μL.

[0078] Example 5

[0079] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that the chromatographic conditions are set as follows:

[0080] The temperature change process of the chromatographic column is as follows: the initial column temperature is 162°C, maintained for 6 minutes, and then increased to the final column temperature of 250°C at a heating rate of 38°C / min, and maintained for 5 minutes; the vaporization chamber temperature is 265°C, the detection chamber temperature is 285°C, the carrier gas is high-purity nitrogen, the flow rate is 3.0mL / min, the split ratio is 40:1, and the injection volume is 1.0μL.

[0081] Embodiment 6-10

[0082] Examples 6-10 provide five methods for detecting the content of isophthalonitrile, which differ from Examples 1-5 only in that the test substance "terephthalonitrile" is replaced by "isophthalonitrile", and other conditions refer to Examples 1-5 respectively.

[0083] Figure 6-9 They are the GC graphs of the first standard solution, the first sample solution, the second sample solution and the second standard solution in Example 6, wherein 1 is naphthalene; 2 is isophthalonitrile.

[0084] Embodiment 11

[0085] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that the temperature change process of the chromatographic column is changed to: the initial column temperature is 180°C and maintained for 3 minutes, and the temperature is increased to the final column temperature of 270°C at a heating rate of 45°C / min and maintained for 2 minutes, and other conditions remain unchanged.

[0086] Example 12

[0087] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that the temperature change process of the chromatographic column is changed to: the initial column temperature is 150°C and maintained for 7 minutes, and the temperature is increased to the final column temperature of 230°C at a heating rate of 20°C / min and maintained for 1 minute, and other conditions remain unchanged.

[0088] Example 13

[0089] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that the "terephthalonitrile standard sample 0.10 g" in step (2) is replaced by "terephthalonitrile standard sample 0.06 g", and the "terephthalonitrile sample 0.10 g" in step (3) is replaced by "terephthalonitrile sample 0.06 g", and other conditions remain unchanged.

[0090] Embodiment 14

[0091] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that the "terephthalonitrile standard sample 0.10 g" in step (2) is replaced by "terephthalonitrile standard sample 0.15 g", and the "terephthalonitrile sample 0.10 g" in step (3) is replaced by "terephthalonitrile sample 0.15 g", and other conditions remain unchanged.

[0092] Embodiment 15

[0093] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that "acetonitrile" in step (1) is replaced by "acetone", and other conditions remain unchanged.

[0094] Example 16

[0095] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that the DB-17 chromatographic column is replaced by a DB-5 chromatographic column (the stationary phase is 5% phenyl-methylpolysiloxane), and other conditions remain unchanged.

[0096] Embodiment 17

[0097] This embodiment provides a method for detecting the content of terephthalonitrile, which differs from Embodiment 1 only in that the DB-17 chromatographic column is replaced by a DB-1 chromatographic column (the stationary phase is 100% methyl polysiloxane), and other conditions remain unchanged.

[0098] Examples 18-24

[0099] Examples 18-24 provide seven methods for detecting the content of isophthalonitrile, which differ from Examples 11-17 only in that the test substance "terephthalonitrile" is replaced by "isophthalonitrile", and other conditions refer to Examples 11-17.

[0100] Comparative Example 1

[0101] This comparative example provides a method for detecting the content of terephthalonitrile, which differs from Example 1 only in that "naphthalene" in step (1) is replaced by "diethyl phthalate", and other conditions remain unchanged.

[0102] Comparative Example 2

[0103] This comparative example provides a method for detecting the content of terephthalonitrile, which differs from Example 1 only in that "naphthalene" in step (1) is replaced by "benzophenone", and other conditions remain unchanged.

[0104] Comparative Examples 3-4

[0105] Comparative Example 3-4 provides two methods for detecting the content of isophthalonitrile, which differ from Comparative Example 1-2 only in that the test substance "terephthalonitrile" is replaced by "isophthalonitrile", and other conditions refer to Comparative Example 1-2.

[0106] The test results in the above embodiments and comparative examples are calculated as follows:

[0107] Calculate the content of the substance to be tested in the sample according to the gas chromatography internal standard method formula:

[0108]

[0109] Where:

[0110] ω 1 ——The mass fraction of the substance to be tested in the sample, expressed in %;

[0111] r 2 ——The average value of the peak area ratio of the analyte to the internal standard in the sample solution;

[0112] m 1 ——The mass of the standard sample, in grams (g);

[0113] ω——mass fraction of the analyte in the standard sample, expressed in %;

[0114] r 1 ——The average value of the peak area ratio between the analyte and the internal standard in the standard solution;

[0115] m 2 ——The mass of the sample, in grams (g).

[0116] Each of the above embodiments and comparative examples was measured 5 times in parallel.

[0117] Test Example 1

[0118] Precision and robustness tests:

[0119] The content of the terephthalonitrile sample was determined using the terephthalonitrile content detection method provided in Examples 1-5, 11-17, Comparative Examples 1 and 2, and the content of the isophthalonitrile sample was determined using the isophthalonitrile content detection method provided in Examples 6-10, 18-24, Comparative Examples 3 and 4. The results are shown in Table 1.

[0120] Table 1

[0121]

[0122]

[0123] The results show that: First, changing the experimental conditions within a certain range has little effect on the test results, indicating that the test method provided by the present invention is highly robust. Secondly, the standard deviation and coefficient of variation of Examples 1-24 are less than 0.8%, indicating that the detection method provided by Examples 1-24 has high precision and meets the detection requirements for the content of terephthalonitrile or isophthalonitrile. Among them, the standard deviation and coefficient of variation of Examples 1-10 are less than 0.3%, indicating that the precision of the detection method provided by Examples 1-10 is higher than that of other examples. The standard deviation and coefficient of variation of Comparative Example 1-4 are greater than 1%, which makes it difficult to meet the detection requirements for the content of terephthalonitrile or isophthalonitrile. The detailed analysis is as follows:

[0124] By comparing Example 1 with Examples 11 and 12 (or Example 6 with Examples 18 and 19), it can be seen that the temperature change process of the chromatographic column has a great influence on the measurement results. Among them, too high or too low initial temperature and final temperature, and too fast temperature change all affect the separation of the components to be measured and impurities. Too slow temperature change will lead to slow analysis speed and cause high boiling point components to be retained in the column.

[0125] By comparing Example 1 with Examples 13 and 14 (or Example 6 with Examples 20 and 21), it can be seen that the weighing range has a great influence on the results. Weighing too little sample will lead to a large relative weighing error, while weighing too much will make the sample difficult to dissolve and the solution stability poor.

[0126] By comparing Example 1 with Example 15 (or Example 6 with Example 22), it can be seen that the choice of solvent has an impact on the test results. Acetonitrile has a suitable boiling point and a suitable solubility for the sample. Choosing acetonitrile as the solvent has better stability of the solution.

[0127] By comparing Example 1 with Example 16 and Example 17 (or Example 6 with Examples 23 and 24), it can be seen that the selection of the stationary phase of the chromatographic column has a great influence on the test results. Selecting a chromatographic column with a stationary phase of 50% phenyl-methylpolysiloxane can completely separate the difficult-to-separate components terephthalonitrile and isophthalonitrile in the sample.

[0128] By embodiment 1 and comparative example 1,2 (or embodiment 6 and comparative example 3,4) contrast can know, the selection of internal standard material has huge impact on test result, the advantage that the present invention selects naphthalene as internal standard material is, on the one hand naphthalene and terephthalonitrile or isophthalonitrile all have ideal separation, in gas chromatography detection, naphthalene goes out peak in front of terephthalonitrile or isophthalonitrile and is not disturbed by any impurity in sample, is conducive to quick detection and accurate quantitative of terephthalonitrile or isophthalonitrile.More importantly, because naphthalene goes out peak in front of terephthalonitrile or isophthalonitrile, therefore the present invention only needs 9min to complete detection, and uses benzophenone commonly used in prior art, diethyl phthalate etc. as internal standard material then needs more than 20min.In a word, selecting naphthalene as internal standard material not only improves the precision of analysis result, and greatly improves analysis speed.

[0129] Test Example 2

[0130] Accuracy test:

[0131] The terephthalonitrile content detection method provided in Examples 1-5 and 11-17 was used to measure the terephthalonitrile standard sample with a known accurate content of 99.3%. The isophthalonitrile content detection method provided in Examples 6-10 and 18-24 was used to measure the isophthalonitrile standard sample with a known accurate content of 99.2%. The results are listed in Table 2.

[0132] Table 2

[0133]

[0134]

[0135] The results show that the absolute value of the relative error of the measurement results of Example 1-24 is less than or equal to 0.5%, indicating that the detection method provided by Example 1-24 has high accuracy and meets the detection requirements of terephthalonitrile or isophthalonitrile content. Among them, the absolute value of the relative error of the measurement results of Example 1-10 is less than or equal to 0.2%, indicating that the accuracy of the detection method provided by Example 1-10 is higher than that of other examples. Since the precision of the method of Comparative Example 1-4 does not meet the requirements, the accuracy is no longer evaluated.

[0136] Test Example 3

[0137] Drawing of standard curve:

[0138] Different masses of terephthalonitrile standard products were weighed respectively, and terephthalonitrile standard solutions with concentrations of 0.00421 g / mL, 0.00889 g / mL, 0.01027 g / mL, 0.01332 g / mL and 0.01548 g / mL were prepared according to the standard solution preparation method in the embodiment, and the samples were injected according to the chromatographic conditions in Example 1, and the results were measured and calculated. The standard curve was drawn with the ratio of terephthalonitrile to internal standard content as the horizontal axis and the peak area ratio as the vertical axis, and the regression equation was obtained as Y=9.4815X-0.000752, and the correlation coefficient R 2 =1.0000, standard curve see Figure 5 .

[0139] Different masses of isophthalonitrile standard products were weighed respectively, and isophthalonitrile standard solutions with concentrations of 0.00512 g / mL, 0.00788 g / mL, 0.00969 g / mL, 0.01268 g / mL and 0.01646 g / mL were prepared according to the standard solution preparation method in the embodiment, and the samples were injected according to the chromatographic conditions in Example 1, and the results were measured and calculated. The standard curve was drawn with the ratio of isophthalonitrile to the internal standard content as the horizontal axis and the peak area ratio as the vertical axis, and the regression equation was obtained as Y=9.4800X+0.000108, and the correlation coefficient R 2 =1.0000, standard curve see Fig.10 .

[0140] The results show that the method for detecting the content of terephthalonitrile or isophthalonitrile provided by the present invention has a wide linear range, and the concentration of the component to be tested has a good linear relationship with the peak area measured by gas chromatography.

[0141] In summary, the present invention provides a gas chromatography internal standard quantitative method, which can be used for the detection of terephthalonitrile content and can also be applied to the detection of isophthalonitrile content. Wherein, the present invention creatively uses naphthalene as internal standard, compared with other internal standards, naphthalene and terephthalonitrile or isophthalonitrile all have ideal separation on the one hand, in gas chromatography detection, naphthalene peaks in front of terephthalonitrile or isophthalonitrile and is not disturbed by any impurities in the sample, which is conducive to the rapid detection and accurate quantification of terephthalonitrile or isophthalonitrile. More importantly, since naphthalene peaks in front of terephthalonitrile or isophthalonitrile, the present invention only needs 9min to complete detection, and using benzophenone, diethyl phthalate etc. commonly used in the prior art as internal standard then needs more than 20min. In a word, the detection method provided by the present invention greatly shortens the gas chromatography analysis time, and the analysis speed is fast, and the precision and accuracy of the detection are higher, which can be applied in medicine detection or pesticide detection.

[0142] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the detection method of terephthalonitrile or isophthalonitrile content and its application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0143] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0144] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for detecting the content of terephthalonitrile or isophthalonitrile, characterized in that: The method for detecting the content of terephthalonitrile or isophthalonitrile comprises the following steps: performing gas chromatography detection on a standard solution and a sample solution prepared by respectively preparing a standard sample and a sample of the object to be detected with an internal standard, and calculating the content of the object to be detected according to the detection result; The analyte includes terephthalonitrile or isophthalonitrile; The internal standard is naphthalene; The column temperature change process in the gas chromatography detection is as follows: the initial column temperature is 160-175°C, the initial column temperature is maintained for 4-6 min, the temperature is increased at a heating rate of 30-40°C / min to a final column temperature of 251-260°C, and the final column temperature is maintained for 3-5 min; the split ratio in the gas chromatography detection is 20:1-50:1; the stationary phase of the chromatographic column in the gas chromatography detection is 50% phenyl-methyl polysiloxane; The preparation method of the standard solution and the sample solution comprises the following steps: (1) dissolving and diluting the internal standard substance with a solvent, and fixing the volume to obtain an internal standard solution; the solvent comprises acetonitrile; (2) dissolving the analyte standard sample in the internal standard solution to obtain the standard sample solution; The sample to be tested is dissolved in the internal standard solution to obtain the sample solution.

2. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 1, wherein: The concentration of the internal standard solution in step (1) is 8-12 mg / mL.

3. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 1, wherein: The concentration of the analyte standard in the standard solution of step (2) is 8-12 mg / mL.

4. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 1, wherein: The concentration of the sample to be tested in the sample solution of step (2) is 8-12 mg / mL.

5. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 1, wherein: The carrier gas in the gas chromatography detection includes nitrogen.

6. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 5, characterized in that: The flow rate of the carrier gas is 1.5-3.5 mL / min.

7. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 1, characterized in that: The temperature of the vaporization chamber in the gas chromatography detection is 260-300°C.

8. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 1, characterized in that: The temperature of the detection chamber in the gas chromatography detection is 280-300°C.

9. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 1, characterized in that: The injection volume in the gas chromatography detection is 0.5-2.0 μL.

10. The method for detecting the content of terephthalonitrile or isophthalonitrile according to claim 1, characterized in that: The method for detecting the content of terephthalonitrile or isophthalonitrile comprises the following steps: (1) Dissolve and dilute the internal standard with a solvent to obtain an internal standard solution with a concentration of 8-12 mg / mL; The internal standard comprises naphthalene, and the solvent comprises acetonitrile; (2) dissolving the analyte standard sample in the internal standard solution to obtain a standard sample solution having a concentration of 8-12 mg / mL; dissolving the analyte sample in the internal standard solution to obtain a sample solution having a concentration of 8-12 mg / mL; The analyte includes terephthalonitrile or isophthalonitrile; (3) Take 0.5-2.0 µL of the standard solution and 0.5-2.0 µL of the sample solution and place them into the gas chromatograph for detection. The chromatographic conditions are as follows: The stationary phase of the chromatographic column is 50% phenyl-methylpolysiloxane; the column temperature change process in gas chromatography detection is as follows: the initial column temperature is 160-175°C, the initial column temperature is maintained for 4-6 min, the temperature is increased at a heating rate of 30-40°C / min to a final column temperature of 251-260°C, and the final column temperature is maintained for 3-5 min; the carrier gas in gas chromatography detection includes nitrogen; the flow rate of the carrier gas is 1.5-3.5 mL / min; the vaporization chamber temperature is 260-300°C; the detection chamber temperature is 280-300°C; the split ratio is 20:1-50:1; and the injection volume is 0.5-2.0 µL.

11. Use of the method for detecting the content of terephthalonitrile or isophthalonitrile as claimed in any one of claims 1 to 10 in pesticide detection or medical detection.

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