A method for analyzing the content of 1,1-dibromomethyl alcohol oxime

Abstract

This invention relates to the field of chemical analysis technology, specifically to an analytical method for the content of 1,1-dibromoformaldehyde oxime. The method includes the following steps: (1) dissolving the standard and the sample to be tested separately in acetonitrile to prepare standard solutions and sample solutions; (2) setting the analytical conditions of the high-performance liquid chromatograph (HPLC), and after the instrument baseline stabilizes, injecting the standard, sample to be tested, sample to be tested, and standard in sequence, calculating the average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution and sample solution respectively; (3) calculating the mass fraction of 1,1-dibromoformaldehyde oxime in the sample to be tested according to the external standard method formula. The analytical method of this invention has strong specificity, good precision, high reliability, and good repeatability, and is particularly suitable for the content analysis of 1,1-dibromoformaldehyde oxime products and for mid-control analysis during the synthesis reaction process.

Description

Technical Field

[0001] This invention relates to the field of chemical analysis technology, specifically to an analytical method for the content of 1,1-dibromoformaldehyde oxime. Background Technology

[0002] 1,1-Dibromoformaldoxime is an important chemical intermediate with the chemical formula CH₂Br₂NOH and CAS Registry number 74213-24-4. It is a colorless crystalline or white powdery solid with a characteristic odor. 1,1-Dibromoformaldoxime can be used in the synthesis of pharmaceuticals and chemical products, and in the field of pesticide synthesis, it is mainly used to synthesize sulfopyrazole as an intermediate.

[0003] High-purity chemical substances are of great significance in scientific research, industrial production, and pesticide research. They provide more reliable, accurate, and repeatable experimental results and ensure product quality. Chromatography is a commonly used method for determining the purity of organic compounds. It separates and determines the purity of organic compounds through the distribution and adsorption of samples between a stationary phase and a mobile phase. Based on the states of the mobile and stationary phases, chromatography includes gas chromatography, liquid chromatography, thin-layer chromatography, gel chromatography, and supercritical fluid chromatography, among which gas chromatography and liquid chromatography are the most commonly used. Due to the highly reactive chemical properties and poor thermal stability of 1,1-dibromoformaldehyde oxime, gas chromatography cannot be used for its analysis. When using liquid chromatography, the high polarity and poor chromatographic retention of 1,1-dibromoformaldehyde oxime make separation from other inorganic impurities difficult. Furthermore, 1,1-dibromoformaldehyde oxime exhibits poor stability under acidic and alkaline conditions and within the chromatographic column, further complicating the analytical separation process.

[0004] Therefore, providing an analytical method that can stably detect the content of 1,1-dibromoformaldehyde oxime is of great importance and practical significance for assessing product quality and the extent of chemical reactions. Summary of the Invention

[0005] To address the lack of stable detection methods for 1,1-dibromoformaldehyde oxime in existing technologies, this invention provides an analytical method for 1,1-dibromoformaldehyde oxime content. This method is highly specific, precise, reliable, and reproducible, and is particularly suitable for content analysis of 1,1-dibromoformaldehyde oxime products and for mid-control analysis during the synthesis reaction process.

[0006] The technical solution of this invention is as follows:

[0007] An analytical method for the content of 1,1-dibromoformaldehyde oxime includes the following steps:

[0008] (1) Dissolve the standard and the sample to be tested separately in acetonitrile to prepare the standard solution and the sample to be tested solution;

[0009] (2) Set the analytical conditions of the high performance liquid chromatograph. After the instrument baseline stabilizes, inject the standard, the test sample, the test sample, and the standard in sequence. Calculate the average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution and the test sample solution respectively.

[0010] Analysis conditions include:

[0011] The chromatographic column is a ZOBAX-RX-C8 reversed-phase column with a column length of 150~250mm, an inner diameter of 4~5mm, and a particle size of 3~5μm. The mobile phase is a mixture of acetonitrile and trifluoroacetic acid aqueous solution, and the detection wavelength is 210~230nm.

[0012] (3) The mass fraction X1 of 1,1-dibromoformaldehyde oxime in the sample to be tested is calculated according to the external standard method formula, as follows.

[0013] ;

[0014] Wherein, A2 represents the average peak area of ​​1,1-dibromoformaldehyde oxime in the sample solution.

[0015] m1 — the quality of the standard product.

[0016] P1 — Mass fraction of 1,1-dibromoformaldehyde oxime in the standard.

[0017] A1—The average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution.

[0018] m2 — the mass of the sample to be tested.

[0019] Furthermore, the concentration range of the standard solution and the test solution is 0.2~2 mg / mL.

[0020] Furthermore, the detection wavelength was 220 nm. Under these conditions, the baseline was stable, and the absorbance value of 1,1-dibromoformaldehyde oxime was moderate, representing the most stable UV absorption wavelength for 1,1-dibromoformaldehyde oxime.

[0021] Furthermore, the chromatographic column has a length of 250 mm, an inner diameter of 4.6 mm, and a particle size of 5 μm.

[0022] Furthermore, the column temperature is 25~30℃. Controlling the column temperature is beneficial to the stability of the detection results. The selected column temperature is slightly higher than room temperature, which is convenient for instrument control. If the temperature is higher, dibromoformaldehyde oxime is easily decomposed, causing detection deviation.

[0023] Furthermore, in the mobile phase, the volume percentage of acetonitrile is 50% to 70%, and the volume percentage of the trifluoroacetic acid aqueous solution is 30% to 50%; preferably, the volume percentage of acetonitrile is 60%, and the volume percentage of the trifluoroacetic acid aqueous solution is 40%.

[0024] Furthermore, the volume percentage of trifluoroacetic acid in the aqueous trifluoroacetic acid solution is 0.05% to 0.1%.

[0025] Furthermore, in step (2), the sample volume for each injection is 5 μL.

[0026] Furthermore, in step (2), the flow rate of the mobile phase is 1 mL / min.

[0027] The beneficial effects of this invention are as follows:

[0028] This invention provides a novel method for detecting the purity of 1,1-dibromoformaldehyde oxime, filling a technological gap in the relevant field. The RX-C8 column used in this invention has a carbon loading more suitable for separating 1,1-dibromoformaldehyde oxime and impurities. Combined with specific mobile phase combinations and other chromatographic conditions, the detection results are stable, achieving complete separation of impurities and dibromoformaldehyde oxime peaks with good peak shape, stable retention time, accurate integral calculation results, good repeatability, and high reliability. This method is particularly suitable for the quality control of 1,1-dibromoformaldehyde oxime products, playing a crucial role and having practical significance in ensuring the quality of the final product. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is the chromatogram of the standard solution in Example 1.

[0031] Figure 2 This is the chromatogram of the sample solution to be tested in Example 1.

[0032] Figure 3 This is the chromatogram of the standard solution in Example 2.

[0033] Figure 4 This is the chromatogram of the sample solution to be tested in Example 2.

[0034] Figure 5 This is the chromatogram of the standard solution in Example 3.

[0035] Figure 6 This is the chromatogram of the sample solution to be tested in Example 3.

[0036] Figure 7 This is the linear relationship graph from Experiment Example 3.

[0037] Figure 8 This is the chromatogram of Comparative Example 1 using the SB-C8 column.

[0038] Figure 9 This is the chromatogram of Comparative Example 1 using the HPH-C8 column.

[0039] Figure 10 This is the chromatogram of Comparative Example 1 using an EC-C8 column.

[0040] Figure 11 This is the chromatogram of Comparative Example 2 when pure water was used instead of the aqueous solution of trifluoroacetic acid.

[0041] Figure 12 This is the chromatogram of Comparative Example 2 when glacial acetic acid was used instead of the aqueous solution of trifluoroacetic acid.

[0042] Figure 13 This is the chromatogram of Comparative Example 2 when phosphoric acid was used instead of the aqueous solution of trifluoroacetic acid.

[0043] Figure 14 This is the chromatogram of the trifluoroacetic acid aqueous solution in Comparative Example 3 when the volume percentage is 20%.

[0044] Figure 15 This is the chromatogram of the trifluoroacetic acid aqueous solution in Comparative Example 3 when the volume percentage is 80%.

[0045] Figures 1-6 , Figures 8-15 In the chromatogram, the horizontal axis represents time and the vertical axis represents absorbance;

[0046] Figure 7 In the figure, the horizontal axis represents the concentration of the standard solution (in g / L), and the vertical axis represents the area of ​​the evaluation peak. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0048] Example 1

[0049] The content of 1,1-dibromoformaldehyde oxime product (purchased from Damas-Beta Chemical Reagent Company, batch number 013455474) was analyzed using the following methods:

[0050] (1) Accurately weigh 0.0495 g of 1,1-dibromoformaldehyde oxime standard, place it in a 50 mL volumetric flask, add 40 mL of acetonitrile, shake to dissolve, and then dilute to the mark with acetonitrile to obtain the standard solution for later use. The mass fraction of 1,1-dibromoformaldehyde oxime in the standard is P1 = 98.7%.

[0051] Accurately weigh 0.0517 g of the sample to be tested, place it in a 50 mL volumetric flask, add 40 mL of acetonitrile, shake to dissolve, and then dilute to the mark with acetonitrile to obtain the sample solution for later use.

[0052] (2) A high-performance liquid chromatograph was used. The chromatographic column was a ZOBAX-RX-C8 column with a column length of 250 mm, an inner diameter of 4.6 mm, and a particle size of 5 μm. The column temperature was 25 °C. The mobile phase was a mixture of 60% (V / V) acetonitrile and 40% (V / V) trifluoroacetic acid aqueous solution (0.1%). The sample volume for each injection was 5 μL, and the flow rate of the mobile phase was 1 mL / min. The detection wavelength was set to 220 nm.

[0053] (3) After the instrument baseline stabilizes, inject the standard, the test sample, the test sample, and the standard in that order. Calculate the average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution and the test sample solution, respectively. The detection data are shown in Table 1 below:

[0054] Table 1 Detection results of Example 1

[0055]

[0056] (4) Calculate the mass fraction of 1,1-dibromoformaldehyde oxime in the sample to be tested according to the external standard method formula, as follows.

[0057] ;

[0058] Wherein, A1 is the average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution.

[0059] A2 — The average peak area of ​​1,1-dibromoformaldehyde oxime in the sample solution.

[0060] m1 — the quality of the standard product.

[0061] m2 — the mass of the sample to be tested.

[0062] P1 — Mass fraction of 1,1-dibromoformaldehyde oxime in the standard.

[0063] X1 — Mass fraction of 1,1-dibromoformaldehyde oxime in the sample to be tested

[0064] The calculated mass fraction of 1,1-dibromoformaldehyde oxime in the sample was 97.2%.

[0065] Figure 1 The peak at 3.927 min is the characteristic peak of 1,1-dibromoformaldehyde oxime. Figure 2 The peak at 3.922 min corresponds to 1,1-dibromoformaldehyde oxime.

[0066] Example 2

[0067] A small-scale test sample, batch 1227-05, yielded 12.9 g of solid. The content of 1,1-dibromoformaldehyde oxime in the product was analyzed using the following methods:

[0068] (1) Accurately weigh 0.0517 g of 1,1-dibromoformaldehyde oxime standard, place it in a 50 mL volumetric flask, add 40 mL of acetonitrile, shake to dissolve, and then dilute to the mark with acetonitrile to obtain the standard solution for later use. The mass fraction of 1,1-dibromoformaldehyde oxime in the standard is P1 = 98.7%.

[0069] Accurately weigh 0.0524 g of the sample to be tested, place it in a 50 mL volumetric flask, add 90 mL of acetonitrile, shake to dissolve, and then dilute to the mark with acetonitrile to obtain the sample solution for later use.

[0070] (2) A high-performance liquid chromatograph was used. The chromatographic column was a ZOBAX-RX-C8 reversed-phase column with a column length of 250 mm, an inner diameter of 4.6 mm, and a particle size of 3.5 μm. The column temperature was 28 °C. The mobile phase was a mixture of 70% (V / V) acetonitrile and 30% (V / V) trifluoroacetic acid aqueous solution (0.05%). The sample volume for each injection was 5 μL, and the flow rate of the mobile phase was 1 mL / min. The detection wavelength was set to 215 nm.

[0071] (3) After the instrument baseline stabilizes, inject the standard, the test sample, the test sample, and the standard in that order. Calculate the average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution and the test sample solution, respectively. The detection data are shown in Table 2 below:

[0072] Table 2 Detection Results of Example 2

[0073]

[0074] (4) The mass fraction of 1,1-dibromoformaldehyde oxime in the test sample was calculated according to the external standard method formula. The specific formula is the same as in Example 1. The calculated mass fraction of 1,1-dibromoformaldehyde oxime in the test sample was 96.0%.

[0075] Figure 3 The peak at 3.153 min corresponds to 1,1-dibromoformaldehyde oxime. Figure 4 The peak at 3.161 min corresponds to 1,1-dibromoformaldehyde oxime.

[0076] Example 3

[0077] A small-scale test sample, batch 1229-01, yielded 85 mL of solution. Besides dibromoformaldehyde oxime, the solution contained other solvents and inorganic bromide ions. The content of 1,1-dibromoformaldehyde oxime in the solution was analyzed using the following steps:

[0078] (1) Accurately weigh 0.0463 g of 1,1-dibromoformaldehyde oxime standard, place it in a 50 mL volumetric flask, add 40 mL of acetonitrile, shake to dissolve, and then dilute to the mark with acetonitrile to obtain the standard solution for later use. The mass fraction of 1,1-dibromoformaldehyde oxime in the standard is P1 = 98.7%.

[0079] Accurately weigh 0.4527 g of the sample to be tested, place it in a 50 mL volumetric flask, add 40 mL of acetonitrile, shake to dissolve, and then dilute to the mark with acetonitrile to obtain the sample solution for later use.

[0080] (2) A high-performance liquid chromatograph with a diode array detector was used. The chromatographic column was a ZOBAX-RX-C8 chiral column with a column length of 200 mm, an inner diameter of 4.0 mm, and a particle size of 3.5 μm. The column temperature was 30 °C. The mobile phase was a mixture of 60% (V / V) acetonitrile and 40% (V / V) trifluoroacetic acid solution (0.1%). The sample volume for each injection was 5 μL, and the flow rate of the mobile phase was 1 mL / min. The detection wavelength was set to 210 nm.

[0081] (3) After the instrument baseline stabilizes, inject the standard, the test sample, the standard, and the test sample in sequence. Calculate the average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution and the test sample solution, respectively. The detection data are shown in Table 3 below:

[0082] Table 3 Detection results of Example 3

[0083]

[0084] (4) The mass fraction of 1,1-dibromoformaldehyde oxime in the test sample was calculated according to the external standard method formula. The specific formula is the same as in Example 1. The calculated mass fraction of 1,1-dibromoformaldehyde oxime in the test sample was 8.52%.

[0085] Figure 5 The peak at 4.349 min corresponds to 1,1-dibromoformaldehyde oxime. Figure 6The peak at 4.367 min corresponds to 1,1-dibromoformaldehyde oxime, and the peak at 2.399 min corresponds to the bromide ion impurity in the sample.

[0086] Test Example 1: Stability Test

[0087] The standard from Example 1 was used as the subject of investigation. Analysis was performed at room temperature at regular intervals for a total of 6 analyses, with peak areas recorded simultaneously. The analytical conditions included: a high-performance liquid chromatograph with a diode array detector; a ZOBAX-RX-C8 reversed-phase column with a column length of 250 mm, an inner diameter of 4.6 mm, and a particle size of 5 μm; a column temperature of 25 °C; a mobile phase consisting of a mixture of 60% (v / v) acetonitrile and 40% (v / v) trifluoroacetic acid aqueous solution (0.1%); a sample volume of 5 μL per injection; a mobile phase flow rate of 1 mL / min; and a detection wavelength of 220 nm.

[0088] The results are shown in Table 4 below. The retention times of the chromatographic peaks were stable, and the RSD was less than 1% when comparing the peak areas, indicating that the analytical method described in this invention has good stability.

[0089] Table 4 Stability test results

[0090]

[0091] Test Example 2 Precision Test

[0092] The small-scale sample 1,1-dibromoformaldehyde oxime from batch 1227-05 in Example 2 was used as the research object. 0.0512 mg of standard and five parallel test samples were weighed and injected in the order of standard solution, test sample solution, test sample solution and standard solution respectively. The mass fraction of 1,1-dibromoformaldehyde oxime in the five parallel test samples was calculated.

[0093] The analytical conditions were as follows: a ZOBAX-RX-C8 reversed-phase column with a length of 250 mm, an inner diameter of 4.6 mm, and a particle size of 5 μm; a column temperature of 28 °C; a mobile phase consisting of a mixture of 70% (v / v) acetonitrile and 30% (v / v) trifluoroacetic acid aqueous solution (0.05%); an injection volume of 5 μL; a mobile phase flow rate of 1 mL / min; and a detection wavelength of 215 nm. The results are shown in Table 5 below. The average mass fraction of 1,1-dibromoformaldehyde oxime was 96.1%, and the RSD was 0.12%, less than 1%, indicating that the analytical method described in this invention has good precision.

[0094] Table 5 Precision test results

[0095]

[0096] Experimental Example 3: Linearity Test

[0097] Weigh a series of standards of different masses, place them in a 50 mL volumetric flask, dissolve them in acetonitrile and dilute to volume, and investigate the relationship between peak area and solution concentration after injection.

[0098] The analytical conditions included: a high-performance liquid chromatograph with a diode array detector was used; the column was a ZOBAX RX-C8 column with a column length of 200 mm, an inner diameter of 4.6 mm, and a particle size of 4 μm; the column temperature was 30 °C; the mobile phase was a mixture of 60% (v / v) acetonitrile and 40% (v / v) trifluoroacetic acid aqueous solution (0.1%); the sample volume for each injection was 5 μL; the flow rate of the mobile phase was 1 mL / min; and the detection wavelength was set to 210 nm. The results are shown in Table 6 below. Figure 7 As shown, the correlation coefficient is 1, indicating that the analysis method provided by this invention meets the linearity requirements.

[0099] Table 6 Results of Linear Experiments

[0100]

[0101] Comparative Example 1

[0102] The sample to be tested in Example 3 was used as the subject of investigation. Different types of chromatographic columns were selected to replace the ZOBAX-RX-C8 reversed-phase chromatographic column for the analysis of 1,1-dibromoformaldehyde oxime content. The other detection conditions were the same as in Example 1.

[0103] like Figure 8 As shown, when using an SB-C8 column with a length of 150 mm, an inner diameter of 4.6 mm, and a packing particle size of 3.5 μm, the retention time of 1,1-dibromoformaldehyde oxime was too early, at 1.792 min, which is close to the dead time. Moreover, the SB-C8 column could not effectively separate 1,1-dibromoformaldehyde oxime from impurity bromide ions in the sample, and therefore could not accurately analyze the content of 1,1-dibromoformaldehyde oxime.

[0104] like Figure 9 As shown, when using an HPH-C8 column with a length of 100 mm, an inner diameter of 3 mm, and a packing particle size of 2.7 μm, the retention time of 1,1-dibromoformaldehyde oxime is 0.839 min, which is close to the dead time, and the separation of 1,1-dibromoformaldehyde oxime from impurity bromide ions is not ideal.

[0105] like Figure 10 As shown, when using an EC-C8 column with a length of 50 mm, an inner diameter of 3 mm, and a packing particle size of 1.8 μm, the retention time of 1,1-dibromoformaldehyde oxime is only 0.537 min, which is close to the dead time; the separation between 1,1-dibromoformaldehyde oxime and impurity peaks is poor, and baseline separation is not achieved.

[0106] Experiments revealed that when the chromatographic column was changed while other detection conditions remained constant, the retention time of 1,1-dibromoformaldehyde oxime was close to its dead time, and it could not be effectively separated from the bromide ions in the sample, thus failing to accurately analyze the content of 1,1-dibromoformaldehyde oxime.

[0107] Comparative Example 2

[0108] Using the standard from Example 1 as the subject of investigation, different components were selected and mixed with acetonitrile as the mobile phase for the analysis of 1,1-dibromoformaldehyde oxime content. The other detection conditions were the same as in Example 1.

[0109] like Figure 11 As shown, when a mixture of 60% (V / V) acetonitrile and 40% (V / V) pure water is used as the mobile phase, the chromatographic peaks are significantly broadened and have poor symmetry, and the elution time is relatively late.

[0110] like Figure 12 As shown, when a mixture of 60% (V / V) acetonitrile and 40% (V / V) glacial acetic acid aqueous solution (0.1%) is used as the mobile phase, the high background absorbance of glacial acetic acid at wavelengths of 210~230nm leads to a significant inverted peak in front of the chromatographic peak, affecting the accuracy of the analytical results.

[0111] like Figure 13 As shown, when a mixture of 60% (V / V) acetonitrile and 40% (V / V) phosphoric acid aqueous solution (0.1%) is used as the mobile phase, the 1,1-dibromoformaldehyde oxime peak shows a plateau and poor symmetry.

[0112] Experiments revealed that changing the polarity modifier in the mobile phase while keeping other detection conditions constant resulted in issues such as asymmetrical chromatographic peaks, plateaus, inverted peaks, and peak bifurcation, making it impossible to accurately analyze the 1,1-dibromoformaldehyde oxime content in the sample.

[0113] Comparative Example 3

[0114] Using the standard from Example 1 as the subject of investigation, the ratio of trifluoroacetic acid aqueous solution in the mobile phase was adjusted to analyze the content of 1,1-dibromoformaldehyde oxime. The other detection conditions were the same as in Example 1.

[0115] like Figure 14 As shown, when a mixture of 80% (v / v) acetonitrile and 20% (v / v) trifluoroacetic acid aqueous solution (0.1%) is used as the mobile phase, the retention time of the chromatographic peak is 2.447 min, which is close to the dead time of the chromatographic column. Furthermore, through analysis of samples containing impurity bromide ions, it was verified that 1,1-dibromoformaldehyde oxime and the impurity bromide ions therein could not be separated under these conditions and could not be used for quantitative analysis.

[0116] like Figure 15 As shown, when a mixture of 20% (v / v) acetonitrile and 80% (v / v) trifluoroacetic acid aqueous solution (0.1%) was used as the mobile phase, the retention time of 1,1-dibromoformaldehyde oxime was 9.681 min, indicating a longer analysis time. Furthermore, a distinct impurity peak appeared 6 min before the main peak, suggesting that 1,1-dibromoformaldehyde oxime decomposed in the column, producing impurities. Therefore, this mobile phase is unsuitable for the analysis of 1,1-dibromoformaldehyde oxime content.

[0117] Based on the above experimental examples 1-3 and comparative examples 1-3, it can be seen that the analytical method for 1,1-dibromoformaldehyde oxime content provided by the present invention has high accuracy and good operability, and can be widely applied to the analysis and detection of 1,1-dibromoformaldehyde oxime content. As can be seen from the above comparative examples 1-3, changing the chromatographic column, mobile phase, and the ratio of the mobile phase will lead to inaccurate analytical results.

[0118] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for analyzing the content of 1,1-dibromoformoxime, characterized in that, Includes the following steps: (1) Dissolve the standard and the sample to be tested separately in acetonitrile to prepare standard solution and sample solution to be tested. The concentration range of the standard solution and sample solution to be tested is 0.2~2 mg / mL. (2) Set the analytical conditions of the high performance liquid chromatograph. After the instrument baseline stabilizes, inject the standard, the test sample, the test sample, and the standard in sequence. Calculate the average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution and the test sample solution respectively. Analysis conditions include: The chromatographic column was a ZOBAX-RX-C8 reversed-phase column with a length of 250 mm, an inner diameter of 4.6 mm, a particle size of 5 μm, and a column temperature of 25–30 °C. The mobile phase was a mixture of acetonitrile and trifluoroacetic acid aqueous solution, and the detection wavelength was 210–230 nm. In the mobile phase, the volume percentage of acetonitrile was 60%, and the volume percentage of trifluoroacetic acid aqueous solution was 40%. (3) The mass fraction X1 of 1,1-dibromoformaldehyde oxime in the sample to be tested is calculated according to the external standard method formula, as follows. ； Wherein, A2 represents the average peak area of ​​1,1-dibromoformaldehyde oxime in the sample solution. m1 — the quality of the standard product. P1 — Mass fraction of 1,1-dibromoformaldehyde oxime in the standard. A1—The average peak area of ​​1,1-dibromoformaldehyde oxime in the standard solution. m2 — the mass of the sample to be tested; The 1,1-dibromoformaldehyde oxime was purchased from Damas. Beta Chemical Reagents Company, batch number 01345547.

2. The analytical method as described in claim 1, characterized in that, The concentration range of the standard solution and the test solution is 0.2~2 mg / mL.

3. The analytical method as described in claim 1, characterized in that, The detection wavelength is 220nm.

4. The analytical method as described in claim 1, characterized in that, The volume percentage of trifluoroacetic acid in the aqueous solution of trifluoroacetic acid is 0.05% to 0.1%.

5. The analytical method as described in claim 1, characterized in that, Step (2) The sample volume for each injection is 5 μL.

6. The analytical method as described in claim 1, characterized in that, In step (2), the flow rate of the mobile phase is 1 mL / min.

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