Method for measuring content of metaldehyde in metaldehyde raw medicine

Abstract

The invention provides a method for measuring the content of metaldehyde in a metaldehyde raw medicine, which comprises the following steps: (A) preparation of an internal standard solution: weighing 1.0 g of an internal standard substance methyl benzoate, placing in a 100mL volumetric flask, dissolving with trichloromethane, diluting to the scale, and shaking uniformly to obtain the internal standard solution; and step (B), preparing a standard sample solution, namely weighing 0.03-0.05 g of a metaldehyde standard sample with the accuracy of 0.0001 g, putting the standard sample into a 10mL volumetric flask, transferring 1mL of the internal standard solution obtained in the step (A), ultrasonically dissolving with trichloromethane, diluting to the scale, and uniformly shaking to obtain the standard sample solution. The structure is reasonable, and the metaldehyde raw medicine with the metaldehyde content of 98% or above can be measured.

Description

Technical Field

[0001] The present application relates to a method for determining the content of metaldehyde in a metaldehyde technical, and specifically, to a method for determining the content of metaldehyde in a metaldehyde technical. Background Art

[0002] Metaldehyde technical is a low-toxic pesticide that kills snails, slugs and other mollusks. It is a moderately toxic stomach poison that acts as an attractant and can destroy the special mucus in the bodies of snails and slugs, causing nerve paralysis and death.

[0003] In the prior art, when preparing metaldehyde technical, the content of metaldehyde in the metaldehyde technical is required to be above 98%, so the content of metaldehyde in the metaldehyde technical needs to be measured. Currently, there is only an enterprise standard for the method of measuring the content of metaldehyde in the metaldehyde technical. Therefore, a method for measuring the content of metaldehyde in the metaldehyde technical is urgently needed to solve the above problems. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide a method for determining the content of metaldehyde in metaldehyde technical to solve the problems raised in the above background technology.

[0005] In order to achieve the above object, the present application provides a method for determining the content of metaldehyde in metaldehyde technical, comprising the following steps:

[0006] Step (A) Preparation of internal standard solution: weigh 1.0 g of internal standard methyl benzoate, place it in a 100 mL volumetric flask, dissolve it in chloroform, dilute it to the mark and shake well to obtain an internal standard solution;

[0007] Step (B) Preparation of standard solution: Weigh 0.03 g-0.05 g of tetraacetaldehyde standard sample, accurate to 0.0001 g, and place it in a 10 mL volumetric flask, then transfer 1 mL of the internal standard solution obtained in step (A), dissolve it with chloroform by ultrasonication, dilute it to the scale and shake it well to obtain a standard solution;

[0008] Step (C) Preparation of sample solution: Weigh 0.03g-0.05g of tetraacetaldehyde sample to an accuracy of 0.0001g, place in a 10mL volumetric flask, then transfer 1mL of the internal standard solution obtained in step (A), dissolve and dilute to the scale with chloroform by ultrasonication, and shake well to obtain a sample solution;

[0009] Step (D) Determination of standard and sample solutions: After the gas chromatograph is stabilized, several injections of standard solution are continuously injected until the relative change of the peak area ratio of metaldehyde to the internal standard between two adjacent injections is less than 1.2%, and then the peak area ratio of metaldehyde to the internal standard in each solution is determined in the order of standard solution, sample solution, sample solution, and standard solution;

[0010] Step (E) Calculation of the content of metaldehyde in the sample: Calculate the content of metaldehyde in the sample by taking the average of the peak area ratios of metaldehyde to internal standard substance in the two sample solutions and the two standard solutions before and after the sample.

[0011] Preferably, the gas chromatograph in step (D) has a hydrogen flame ionization detector.

[0012] Preferably, the operating conditions of the gas chromatograph in step (D) are as follows:

[0013] Column temperature: initial temperature 40℃, maintain for 2 min, increase to 160℃ at a rate of 40℃ / min, maintain at 160℃ for 3 min, then increase to 200℃ at a rate of 40℃ / min and maintain for 3 min;

[0014] Vaporization chamber temperature: 100°C;

[0015] Detector temperature: 180℃-250℃;

[0016] Gas flow rate (mL / min): carrier gas (N2) 2.5, hydrogen 30, air 300;

[0017] Split ratio: 20:1;

[0018] Injection volume: 1.0 μL;

[0019] Retention time: metaldehyde 6-7min, methyl benzoate 7-8min.

[0020] Preferably, the chromatographic column of the gas chromatograph in step (D) is: a 30m×0.32mm (id) capillary column and the inner wall is coated with (5%-phenyl)-methylpolysiloxane stationary liquid with a film thickness of 1.0 μm.

[0021] Preferably, the calculation formula of the metaldehyde content in the sample in step (E) is as follows:

[0022] Where:

[0023] w1—mass fraction of metaldehyde in the sample, %;

[0024] r2—the average value of the peak area ratio of metaldehyde to internal standard in the sample solution;

[0025] m1—mass of standard sample, in grams (g);

[0026] w b1 —Mass fraction of metaldehyde in the standard sample, %;

[0027] r1—average value of the peak area ratio of metaldehyde to internal standard in the standard solution;

[0028] m2—mass of the sample, in grams (g).

[0029] Preferably, the chloroform used in the internal standard solution in step (A), the standard sample solution in step (B) and the sample solution in step (C) are all chromatographic grade chloroform.

[0030] Preferably, the ultrasonic dissolution time in step (B) and step (C) is 1-3 minutes.

[0031] According to a method for determining the content of metaldehyde in metaldehyde technical drug of the present application, the method comprises the following steps: (A) preparing an internal standard solution using methyl benzoate as an internal standard, (B) preparing a standard sample solution, (C) preparing a sample solution, (D) determining the standard sample and the sample solution, and (E) calculating the content of metaldehyde in the sample, thereby testing the content of metaldehyde in the metaldehyde technical drug to determine whether the content is above 98%, i.e., meeting the index requirement of the content of metaldehyde, so as to determine whether the quality is qualified. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0033] Figure 1 A gas chromatogram of a metaldehyde standard sample solution in a method for determining the content of metaldehyde in a metaldehyde technical according to an embodiment of the present application;

[0034] Figure 2 The gas chromatogram of the sample solution of metaldehyde in Example 1 of a method for determining the content of metaldehyde in metaldehyde technical according to one embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the technical means, creative features, objectives and effects achieved by this application easy to understand, this application is further explained below in conjunction with specific implementation methods.

[0036] like Figure 1-Figure 2 As shown, Figure 1-Figure 2 The reference numerals 1 and 2 are all metaldehyde and methyl benzoate, respectively. The present application provides a technical solution: a method for determining the content of metaldehyde in metaldehyde technical, comprising the following steps:

[0037] Step (A) Preparation of internal standard solution: weigh 1.0 g of internal standard methyl benzoate, place it in a 100 mL volumetric flask, dissolve it in chloroform, dilute it to the mark and shake well to obtain an internal standard solution;

[0038] Step (B) Preparation of standard solution: Weigh 0.03 g-0.05 g of tetraacetaldehyde standard sample, accurate to 0.0001 g, and place it in a 10 mL volumetric flask, then transfer 1 mL of the internal standard solution obtained in step (A), dissolve it with chloroform by ultrasonication, dilute it to the scale and shake it well to obtain a standard solution;

[0039] Step (C) Preparation of sample solution: Weigh 0.03g-0.05g of tetraacetaldehyde sample to an accuracy of 0.0001g, place in a 10mL volumetric flask, then transfer 1mL of the internal standard solution obtained in step (A), dissolve and dilute to the scale with chloroform by ultrasonication, and shake well to obtain a sample solution;

[0040] Step (D) Determination of standard and sample solutions: After the gas chromatograph is stabilized, several injections of standard solution are continuously injected until the relative change of the peak area ratio of metaldehyde to the internal standard between two adjacent injections is less than 1.2%, and then the peak area ratio of metaldehyde to the internal standard in each solution is determined in the order of standard solution, sample solution, sample solution, and standard solution;

[0041] Step (E) Calculation of the content of metaldehyde in the sample: Calculate the content of metaldehyde in the sample by taking the average of the peak area ratios of metaldehyde to internal standard substance in the two sample solutions and the two standard solutions before and after the sample.

[0042] Preferably, the gas chromatograph in step (D) has a hydrogen flame ionization detector.

[0043] Preferably, the operating conditions of the gas chromatograph in step (D) are as follows:

[0044] Column temperature: initial temperature 40℃, maintain for 2 min, increase to 160℃ at a rate of 40℃ / min, maintain at 160℃ for 3 min, then increase to 200℃ at a rate of 40℃ / min and maintain for 3 min;

[0045] Vaporization chamber temperature: 100°C;

[0046] Detector temperature: 180℃-250℃, where the detector is a hydrogen flame ionization detector;

[0047] Gas flow rate (mL / min): carrier gas (N2) 2.5, hydrogen 30, air 300;

[0048] Split ratio: 20:1;

[0049] Injection volume: 1.0 μL;

[0050] Retention time: metaldehyde 6-7min, methyl benzoate 7-8min.

[0051] Preferably, the chromatographic column of the gas chromatograph in step (D) is: a 30m×0.32mm (id) capillary column and the inner wall is coated with (5%-phenyl)-methylpolysiloxane stationary liquid with a film thickness of 1.0 μm.

[0052] Preferably, the calculation formula of the metaldehyde content in the sample in step (E) is as follows:

[0053] Where:

[0054] w1—mass fraction of metaldehyde in the sample, %;

[0055] r2—the average value of the peak area ratio of metaldehyde to internal standard in the sample solution;

[0056] m1—mass of standard sample, in grams (g);

[0057] w b1 —Mass fraction of metaldehyde in the standard sample, %;

[0058] r1—average value of the peak area ratio of metaldehyde to internal standard in the standard solution;

[0059] m2—mass of the sample, in grams (g), where the mass fraction of metaldehyde in the standard sample is known, and the mass fraction of metaldehyde in the standard sample is purchased from the Pesticide Standards Association. They will give specific values, generally requiring that the content be greater than 99% when the standard sample is used.

[0060] Preferably, the chloroform used in the internal standard solution in step (A), the standard sample solution in step (B) and the sample solution in step (C) are all chromatographic grade chloroform.

[0061] Preferably, the ultrasonic dissolution time in step (B) and step (C) is 1-3 minutes.

[0062] The following describes a specific embodiment of a method for determining the content of metaldehyde in metaldehyde technical according to the present invention.

[0063] Example 1: Step (A1) Preparation of internal standard solution: Weigh 1.0 g of internal standard substance methyl benzoate, place in a 100 mL volumetric flask, dissolve and dilute to scale with chloroform and shake well to obtain an internal standard solution;

[0064] Step (B1) Preparation of standard solution: Weigh 0.0312 g of metaldehyde standard sample, accurate to 0.0001 g, place in a 10 mL volumetric flask, then transfer 1 mL of the internal standard solution obtained in step (A1), dissolve in chloroform by ultrasonication for 1 minute, dilute to the scale and shake well to obtain a standard solution, wherein the mass fraction of metaldehyde in the standard sample is 99.4%;

[0065] Step (C1) Preparation of sample solution: Weigh 0.0310 g of tetraacetaldehyde sample to an accuracy of 0.0001 g, place in a 10 mL volumetric flask, then transfer 1 mL of the internal standard solution obtained in step (A1), dissolve in chloroform by ultrasonication for 1 minute, dilute to scale and shake well to obtain a sample solution;

[0066] Step (D1) Determination of standard and sample solutions: After the instrument is stabilized by using a gas chromatograph, several injections of standard solution are continuously injected until the relative change of the peak area ratio of metaldehyde to the internal standard between two adjacent injections is less than 1.2%, and then the peak area ratio of metaldehyde to the internal standard in each solution is measured in the order of standard solution, sample solution, sample solution, and standard solution, wherein the operating conditions of the gas chromatograph are as follows:

[0067] Column temperature: initial temperature 40℃, maintain for 2 min, increase to 160℃ at a rate of 40℃ / min, maintain at 160℃ for 3 min, then increase to 200℃ at a rate of 40℃ / min and maintain for 3 min;

[0068] Vaporization chamber temperature: 100°C;

[0069] Detector temperature: 180°C;

[0070] Gas flow rate (mL / min): carrier gas (N2) 2.5, hydrogen 30, air 300;

[0071] Split ratio: 20:1;

[0072] Injection volume: 1.0 μL;

[0073] Retention time: metaldehyde 6.4 min, methyl benzoate 7.7 min;

[0074] The chromatographic column of the gas chromatograph is: 30m×0.32mm (id) capillary column with the inner wall coated with (5%-phenyl)-methyl polysiloxane stationary liquid, with a film thickness of 1.0μm;

[0075] Step (E1) Calculation of the content of metaldehyde in the sample: Calculate the content of metaldehyde in the sample by taking the average of the peak area ratios of metaldehyde to internal standard substance in the two sample solutions and the two standard solutions before and after the sample.

[0076] Example 2: Preparation of internal standard solution in step (A2): Weigh 1.0 g of internal standard substance methyl benzoate, place in a 100 mL volumetric flask, dissolve and dilute to scale with chloroform and shake well to obtain an internal standard solution;

[0077] Step (B2) Preparation of standard solution: Weigh 0.0309 g of metaldehyde standard sample, accurate to 0.0001 g, place in a 10 mL volumetric flask, then transfer 1 mL of the internal standard solution obtained in step (A2), dissolve in chloroform by ultrasonication for 1 minute, dilute to the scale and shake well to obtain a standard solution, wherein the mass fraction of metaldehyde in the standard sample is 99.4%;

[0078] Step (C2) Preparation of sample solution: Weigh 0.0313 g of tetraacetaldehyde sample to an accuracy of 0.0001 g, place in a 10 mL volumetric flask, then transfer 1 mL of the internal standard solution obtained in step (A2), dissolve in chloroform by ultrasonication for 1 minute, dilute to scale and shake well to obtain a sample solution;

[0079] Step (D2) Determination of standard and sample solutions: After the instrument is stabilized by using a gas chromatograph, several injections of standard solution are continuously injected until the relative change of the peak area ratio of metaldehyde to the internal standard between two adjacent injections is less than 1.2%, and then the peak area ratio of metaldehyde to the internal standard in each solution is measured in the order of standard solution, sample solution, sample solution, and standard solution, wherein the operating conditions of the gas chromatograph are as follows:

[0080] Column temperature: initial temperature 40℃, maintain for 2 min, increase to 160℃ at a rate of 40℃ / min, maintain at 160℃ for 3 min, then increase to 200℃ at a rate of 40℃ / min and maintain for 3 min;

[0081] Vaporization chamber temperature: 100°C;

[0082] Detector temperature: 250°C;

[0083] Gas flow rate (mL / min): carrier gas (N2) 2.5, hydrogen 30, air 300;

[0084] Split ratio: 20:1;

[0085] Injection volume: 1.0 μL;

[0086] Retention time: metaldehyde 6.3 min, methyl benzoate 7.6 min;

[0087] The chromatographic column of the gas chromatograph is: 30m×0.32mm (id) capillary column with the inner wall coated with (5%-phenyl)-methyl polysiloxane stationary liquid, with a film thickness of 1.0μm;

[0088] Step (E2) Calculation of the content of metaldehyde in the sample: Calculate the content of metaldehyde in the sample by taking the average of the peak area ratios of metaldehyde to the internal standard substance in the two sample solutions and the two standard solutions before and after the sample.

[0089] According to the peak area ratios of metaldehyde to the internal standard in each solution of the standard solution, the sample solution, the sample solution, and the standard solution measured by gas chromatography in Example 1-2, the data of the metaldehyde content in the sample are calculated as shown in Table 1 below:

[0090]

[0091]

[0092] Table 1

[0093] A method for determining the content of metaldehyde in metaldehyde technical raw materials. When the content of metaldehyde in the metaldehyde technical raw materials is tested by the method and is above 98%, the index requirement of the metaldehyde content is met, so as to determine whether the quality is qualified.

[0094] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for determining the content of metaldehyde in metaldehyde original medicine, characterized in that: The following steps are involved: Step (A) Preparation of internal standard solution: weigh 1.0 g of internal standard methyl benzoate, place it in a 100 mL volumetric flask, dissolve it in chloroform, dilute it to the mark and shake well to obtain an internal standard solution; Step (B) Preparation of standard solution: Weigh 0.03 g-0.05 g of tetraacetaldehyde standard sample, accurate to 0.0001 g, and place it in a 10 mL volumetric flask, then transfer 1 mL of the internal standard solution obtained in step (A), dissolve it with chloroform by ultrasonication, dilute it to the scale and shake it well to obtain a standard solution; Step (C) Preparation of sample solution: Weigh 0.03g-0.05g of tetraacetaldehyde sample to an accuracy of 0.0001g, place in a 10mL volumetric flask, then transfer 1mL of the internal standard solution obtained in step (A), dissolve and dilute to the scale with chloroform by ultrasonication, and shake well to obtain a sample solution; Step (D) Determination of standard and sample solutions: After the gas chromatograph is stabilized, several injections of standard solution are continuously injected until the relative change of the peak area ratio of metaldehyde to the internal standard between two adjacent injections is less than 1.2%, and then the peak area ratio of metaldehyde to the internal standard in each solution is determined in the order of standard solution, sample solution, sample solution, and standard solution; Step (E) Calculation of the content of metaldehyde in the sample: Calculate the content of metaldehyde in the sample by taking the average of the peak area ratios of metaldehyde to internal standard substance in the two sample solutions and the two standard solutions before and after the sample.

2. The method for determining the content of metaldehyde in metaldehyde technical according to claim 1, characterized in that: The gas chromatograph in the step (D) has a hydrogen flame ionization detector.

3. A method for determining the content of metaldehyde in metaldehyde technical according to claim 2, characterized in that: The operating conditions of the gas chromatograph in the step (D) are as follows: Column temperature: initial temperature 40℃, maintain for 2 min, increase to 160℃ at a rate of 40℃ / min, maintain at 160℃ for 3 min, then increase to 200℃ at a rate of 40℃ / min and maintain for 3 min; Vaporization chamber temperature: 100°C; Detector temperature: 180℃-250℃; Gas flow rate (mL / min): carrier gas (N2) 2.5, hydrogen 30, air 300; Split ratio: 20:1; Injection volume: 1.0 μL; Retention time: metaldehyde 6-7min, methyl benzoate 7-8min.

4. The method for determining the content of metaldehyde in metaldehyde technical according to claim 1, characterized in that: The chromatographic column of the gas chromatograph in the step (D) is: a 30m×0.32mm (id) capillary column and the inner wall is coated with (5%-phenyl)-methylpolysiloxane stationary liquid with a film thickness of 1.0 μm.

5. The method for determining the content of metaldehyde in metaldehyde technical according to claim 1, characterized in that: The calculation formula of the metaldehyde content in the sample in step (E) is as follows: Where: w1—mass fraction of metaldehyde in the sample, %; r2—the average value of the peak area ratio of metaldehyde to internal standard in the sample solution; m1—mass of the standard sample, in grams (g); w b1 —Mass fraction of metaldehyde in the standard sample, %; r1—average value of the peak area ratio of metaldehyde to internal standard in the standard solution; m2—mass of the sample, in grams (g).

6. The method for determining the content of metaldehyde in metaldehyde technical according to claim 1, characterized in that: The chloroform used in the internal standard solution in step (A), the standard sample solution in step (B) and the sample solution in step (C) are all chromatographic grade chloroform.

7. The method for determining the content of metaldehyde in metaldehyde technical according to claim 1, characterized in that: The ultrasonic dissolution time in step (B) and step (C) is 1-3 minutes.

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