Isomer Detection Method for Tedizolid Phosphate Intermediate

Abstract

The present invention discloses a method for detecting isomers of a tedizolid phosphate intermediate, and the tedizolid phosphate intermediate is (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one. By means of a specific sample solvent and chromatographic conditions, the present invention can effectively separate the chromatographic peaks of the tedizolid phosphate intermediate (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one from its isomers, accurately determine the isomer content, and the determination result is stable, reliable and highly specific.

Description

Technical Field

[0001] The present invention belongs to the field of pharmaceutical analysis, and particularly relates to a method for detecting isomers of the intermediate (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one of tedizolid phosphate. Background Art

[0002] Tedizolid phosphate, also known as Tedizolid phosphate, Tedizolid phosphate, and Tedizolid phosphate, its phase III clinical trial results show that the clinical effect is comparable to that of linezolid, the adverse reactions in terms of gastrointestinal tract and thrombocytopenia are less than those of linezolid, and the incidence of drug resistance is also lower. It is more superior to vancomycin in terms of drug tolerance.

[0003] Tedizolid phosphate was developed by Dong-A Pharmaceutical and was approved for marketing by the US Food and Drug Administration (FDA) on June 20, 2014. The trade name is SIVEXTRO. This drug belongs to the second-generation oxazolidinone antibiotics and is a protein synthesis inhibitor used for the treatment of severe Gram-positive bacterial infections. The chemical name of tedizolid phosphate is (R)-3-(4-(2-(2-methyltetrazol-5-yl)pyridin-5-yl)-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one phosphate, and the molecular formula is C 17 H 16 FN6O6P, and the structural formula is as follows:

[0004]

[0005] So far, there have been many reports on the synthesis process of tedizolid phosphate, including the synthesis process of the original research manufacturer, and many synthetic routes are involved. One of the synthetic routes of tedizolid phosphate is as follows:

[0006]

[0007] The above-mentioned synthesis process of tedizolid phosphate consists of a total of 4-step reactions and is adopted by most domestic manufacturers at present. It can be seen from the above process that IN2 is the key intermediate for synthesizing the raw material drug of tedizolid phosphate.

[0008] The chemical name of IN2 is (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one. To ensure the quality of the tedizolid phosphate API, it is necessary to control its isomers to prevent the excessive content of its isomers from participating in the next reaction to form by-products, resulting in the exceeding of related substances of the tedizolid phosphate API.

[0009] The chemical structural formula of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one is as follows:

[0010]

[0011] Analysis of the chemical structure and synthesis process of tedizolid phosphate intermediate reveals that: this intermediate contains isomers, and its chemical name is (S)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one, which is difficult to separate from the tedizolid phosphate intermediate, resulting in unstable quality. Developing an analytical detection method for this isomer and conducting qualitative and quantitative analysis can strictly control the quality of the intermediate (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one, thereby ensuring that the quality of the final product, tedizolid phosphate API, meets the requirements. In the present invention, the isomer of this intermediate is named impurity H in the impurity profile of tedizolid phosphate. The basic information of impurity H is shown in the following table:

[0012]

[0013] There is no prior art report on the detection method for the isomer (impurity H) of the intermediate of tedizolid phosphate API. It can be seen that developing a content analysis method for the isomer of its intermediate is very important for effectively controlling the quality of tedizolid phosphate API or bulk drug, and also has guiding significance for the synthesis process of tedizolid phosphate API or bulk drug. Summary of the Invention

[0014] To effectively control the quality of the intermediate (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one of tedizolid phosphate and further control the quality of tedizolid phosphate, the present invention provides a method for detecting the isomer of the intermediate of tedizolid phosphate, which uses high performance liquid chromatography for detection, and the specific steps are as follows:

[0015] a. Preparation of the test solution: Take the intermediate of tedizolid phosphate to be tested, dissolve it with the mobile phase to obtain the solution.

[0016] b. Preparation of the system suitability solution: Take the reference substance of the intermediate of tedizolid phosphate and the reference substance of its isomer respectively, dissolve them with the mobile phase, and mix to obtain the system suitability solution.

[0017] c. Inject the test solution and the system suitability solution into the chromatograph respectively. The chromatographic conditions are as follows: Chromatographic column: packed with octadecylsilane chemically bonded silica gel; Mobile phase: n-hexane - isopropanol - trifluoroacetic acid with a volume ratio of 50 - 80:50 - 20:0.1.

[0018] The intermediate of tedizolid phosphate is (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one.

[0019] Furthermore, the mass-volume ratio of the tedizolid phosphate intermediate described in step a to the mobile phase is 0.5 - 2 mg: 1 ml, preferably 1 mg: 1 ml.

[0020] Furthermore, in the system suitability solution described in step b, the concentration of the tedizolid phosphate intermediate reference substance is 0.5 - 2 mg / ml, and the concentration of its isomer reference substance is 0.5 - 2 μg / ml. Preferably, the concentration of the tedizolid phosphate intermediate reference substance is 1 mg / ml, and the concentration of its isomer reference substance is 1 μg / ml.

[0021] Furthermore, the chromatographic column described in step c is CHIRALPAK IA, with a specification of 4.6×250 mm, 5 μm; the volume ratio of n-hexane - isopropanol - trifluoroacetic acid is 60:40:0.1.

[0022] Furthermore, in the chromatographic conditions described in step c, the detection wavelength is 220 - 260 nm, the flow rate is 0.5 - 1.5 ml / min, the column temperature is 30 - 40 °C, and the injection volume is 10 - 20 μl.

[0023] More specifically, in the chromatographic conditions, the detection wavelength is 240 nm, the flow rate is 1.0 ml / min, the column temperature is 30 °C, and the injection volume is 10 μl.

[0024] Furthermore, in the chromatogram of the test solution, chromatographic peaks corresponding to the isomer chromatographic peaks in the chromatogram of the system suitability solution appear, that is, the test sample contains isomers.

[0025] Furthermore, the isomer is (S)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one.

[0026] The present invention also provides a method for determining the content of isomers of the tedizolid phosphate intermediate, and the specific operation steps are as follows:

[0027] 1) Detect according to the aforementioned method;

[0028] 2) Calculate the content of related substances, and the calculation formula is as follows:

[0029]

[0030] Wherein, X i %: the content of isomers in the test sample, A i : the peak area of the isomer in the test sample, A: the sum of the areas of all peaks in the test solution.

[0031] The present invention relates to a method for detecting isomers in tedizolid phosphate intermediates. Through specific sample solvents and chromatographic conditions, the chromatographic peaks of the tedizolid phosphate intermediate (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one and its isomers can be effectively separated, the content of the isomers can be accurately determined, the measurement results are stable and reliable, and the specificity is strong. The results of the methodological verification show that the present invention meets the requirements of the "Chinese Pharmacopoeia" 2020 edition for analytical methodology, thereby effectively controlling the quality of tedizolid phosphate intermediates, improving the quality of tedizolid phosphate bulk drugs, and effectively monitoring the synthesis process of tedizolid phosphate intermediates and the synthesis process of tedizolid phosphate bulk drugs, with specific practical promotion and application value.

[0032] Obviously, based on the above content of the present invention, according to the common general knowledge and customary means in the art, without departing from the above basic technical idea of the present invention, various other forms of modifications, substitutions or changes can be made.

[0033] The following is a further detailed description of the above content of the present invention through specific embodiments in the form of examples. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention belong to the scope of the present invention. Description of the Drawings

[0034] Figure 1 HPLC chromatogram of the test solution in Example 1;

[0035] Figure 2 HPLC chromatogram of the test solution in Example 2;

[0036] Figure 3 Typical chromatogram of the system suitability solution;

[0037] Figure 4 1H-NMR spectrum of the reference substance of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one;

[0038] Figure 5 MS spectrum of the reference substance of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one;

[0039] Figure 6 HPLC purity of the reference substance of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one;

[0040] Figure 7 1H-NMR spectrum of the reference substance of (S)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one;

[0041] Figure 8(S)-3-(4-Bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one reference substance MS spectrum;

[0042] Figure 9 (S)-3-(4-Bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one reference substance HPLC purity. Detailed implementation mode

[0043] (1) Materials

[0044] (R)-3-(4-Bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one sample (provided by Sichuan Meiyugao Biopharmaceutical Co., Ltd., batch numbers F20220401; F20220501)

[0045] (R)-3-(4-Bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one reference substance (provided by Sichuan Meiyugao Biopharmaceutical Co., Ltd., batch number 210101, HNMR spectrum as Figure 4 shown, MS spectrum as Figure 5 shown, HPLC purity spectrum as Figure 6 shown)

[0046] Isomer (S)-3-(4-Bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one reference substance (provided by Sichuan Meiyugao Biopharmaceutical Co., Ltd., batch number 210201, HNMR spectrum as Figure 7 shown, MS spectrum as Figure 8 shown, HPLC purity spectrum as Figure 9 shown)

[0047] (2) Main instruments

[0048] High performance liquid chromatograph: Shimadzu LC-20AT, chromatographic column: CHIRALPAK IA, 4.6×250mm, 5μm.

[0049] Example 1 Determination of the isomer (impurity H) content of the intermediate (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one of tedizolid phosphate

[0050] (1) Preparation of the test solution: Accurately weigh (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one (batch number F20220401), dissolve it with the mobile phase, and prepare a test solution with a concentration of 1mg / ml.

[0051] (2) Preparation of the system suitability solution:

[0052] Reference substance stock solution of impurity H: Accurately weigh the reference substance of impurity H, dissolve it with the mobile phase, and prepare a solution with a concentration of 200μg / ml as the reference substance stock solution of impurity H.

[0053] System suitability solution: Weigh accurately 20 mg of the reference substance of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one, and accurately measure 0.1 ml of the stock solution of impurity H reference substance, transfer to a 20-ml volumetric flask, dissolve with the mobile phase, shake well, and make up the volume to the mark. This is the system suitability solution.

[0054] (3) Chromatographic condition settings

[0055] Chromatographic column: CHIRALPAK IA, specification 4.6×250 mm, 5 μm;

[0056] Detection wavelength: 240 nm;

[0057] Flow rate: 1 ml / min;

[0058] Column temperature: 30 °C.

[0059] Mobile phase: n-hexane - isopropanol - trifluoroacetic acid (60:40:0.1);

[0060] Isocratic elution.

[0061] (4) Determination

[0062] Respectively inject 10 μl of the test solution and the system suitability solution into the chromatograph, record the chromatogram, and respectively record the peak area A of impurity H in the test substance i and the sum of the peak areas A of all peaks in the test solution. Calculate the content of impurity H in the test substance by the area normalization method. The calculation formula is as follows:

[0063]

[0064] where X i %: The content of impurity H in the test substance,

[0065] A i : The peak area of impurity H in the test substance is 16865,

[0066] A: The sum of the peak areas of all peaks in the test solution is 33262316. The HPLC chromatogram of the test solution is shown in Figure 1 ; The HPLC chromatogram of the system suitability solution is shown in Figure 3 .

[0067] Calculation result: The content of impurity H in the (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one sample with batch number F20220401 is: impurity H = 0.051%.

[0068] Determination of the Content of the Isomer (Impurity H) of the Intermediate of Tedizolid Phosphate (R)-3-(4-Bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one in Example 2

[0069] (1) Preparation of the test solution: Accurately weigh (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one (batch number F20220501), dissolve it in the mobile phase, and prepare a test solution with a concentration of 1 mg / ml.

[0070] (2) Preparation of the system suitability solution:

[0071] Stock solution of the reference substance for impurity H: Accurately weigh the reference substance for impurity H, dissolve it in the mobile phase, and prepare a solution with a concentration of 200 μg / ml as the stock solution of the reference substance for impurity H.

[0072] System suitability solution: Accurately weigh 20 mg of the reference substance of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one, accurately measure 0.1 ml of the stock solution of the reference substance for impurity H, place it in a 20-ml volumetric flask, dissolve it with the mobile phase, shake well, and make up the volume to obtain the system suitability solution.

[0073] (3) Setting of chromatographic conditions

[0074] Chromatographic column: CHIRALPAK IA, specification 4.6×250 mm, 5 μm;

[0075] Detection wavelength: 240 nm;

[0076] Flow rate: 1 ml / min;

[0077] Column temperature: 30 °C.

[0078] Mobile phase: n-hexane - isopropanol - trifluoroacetic acid (60:40:0.1);

[0079] Isocratic elution.

[0080] (4) Determination

[0081] Respectively inject 10 μl of the test solution and the system suitability solution into the chromatograph, record the chromatogram, and respectively record the peak area A of impurity H in the test sample i and the sum of the peak areas of all peaks in the test solution A. Calculate the content of impurity H in the test sample by the area normalization method. The calculation formula is as follows:

[0082]

[0083] Among them, X i %: The content of impurity H in the test sample,

[0084] Ai : The peak area of impurity H in the test sample was 16,908,

[0085] A: The sum of the peak areas of all peaks in the test sample solution was 32,790,554. The HPLC chromatogram of the test sample solution is shown in Figure 2 ; The HPLC chromatogram of the system suitability solution is shown in Figure 3 .

[0086] Calculation result: The content of impurity H in the sample of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one with batch number F20220401 was: Impurity H = 0.052%.

[0087] The beneficial effects of the present invention are further illustrated by the following experimental examples:

[0088] Experimental Example 1 System Suitability

[0089] Instrument: High-performance liquid chromatograph: Shimadzu LC-20AT, chromatographic column: CHIRALPAK IA, 4.6×250 mm, 5 μm, flow rate: 1.0 ml / min, chromatographic column temperature: 30 °C, injection volume: 10 μl, detector wavelength: 240 nm, mobile phase: n-hexane - isopropanol - trifluoroacetic acid (60:40:0.1), isocratic elution

[0090] (1) Blank solution (mobile phase): n-hexane - isopropanol - trifluoroacetic acid (60:40:0.1)

[0091] (2) Stock solution of impurity H reference substance: Weigh accurately 10 mg of impurity H reference substance and place it in a 50 ml volumetric flask. Dilute and make up the volume with the mobile phase (isomer: 200 μg / ml).

[0092] (3) System suitability solution: Weigh accurately 20 mg of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one reference substance and accurately measure 0.1 ml of the stock solution of impurity H reference substance, place them in a 20 ml volumetric flask, dissolve with the mobile phase, shake well, and make up the volume. This is the system suitability solution. ((R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one 1 mg / ml, impurity H reference substance 1 μg / ml)

[0093] (4) Impurity H localization solution: Transfer 1.0 ml of the stock solution of impurity H reference substance to a 20 ml volumetric flask, dissolve and make up the volume with the mobile phase. (Impurity H: 10 μg / ml)

[0094] (5) Test sample solution: Weigh accurately 20 mg of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one in a 20 ml volumetric flask, dissolve and make up the volume with the mobile phase.

[0095] Inject the blank solution, system suitability solution, and sample solution according to the chromatographic conditions, record the chromatographic process, and the results are shown in Table 1.

[0096] Table 1 System Suitability

[0097]

[0098] Conclusion: The resolution is 4.74, greater than 1.5, and the system suitability is good.

[0099] Experimental Example 2 Specificity

[0100] Experimental conditions, liquid chromatography method, and solution preparation are the same as in Experimental Example 1.

[0101] The method specificity examines peak identification and selectivity. Inject the blank solution and the impurity H localization solution separately, and record the chromatograms. The results are shown in Table 2.

[0102] Table 2 Specificity

[0103] Solution Name Substance Name Solution Concentration Retention Time Impurity H Localization Solution Impurity H 10.30 μg / ml 7.158

[0104] Conclusion: The retention time of impurity H in the system suitability solution is the same as that in the impurity H localization solution, and the specificity is good.

[0105] Experimental Example 3 Detection Limit and Quantification Limit

[0106] Experimental conditions, liquid chromatography method, and solution preparation are the same as in Experimental Example 1.

[0107] For known related substances, the detection limit (LOD) and quantification limit (LOQ) are determined based on the signal-to-noise ratio. Dilute the known concentration of the isomer stock solution to a low concentration and inject it. The concentration with a signal-to-noise ratio S / N≥10 is determined as the quantification limit, and S / N = 2 - 4 is determined as the detection limit. The test results are shown in Table 3.

[0108] Table 3 Quantification Limit and Detection Limit

[0109]

[0110] Experimental Example 4 Linearity and Range

[0111] Experimental conditions, liquid chromatography method, and solution preparation are the same as in Experimental Example 1.

[0112] For known related substances, 5 points are selected for study in the range from the LOQ concentration to not less than 200% of the specification concentration.

[0113] For the main component, 5 points are selected for study in the range from the LOQ concentration to not less than 200% of the specification concentration.

[0114] The linear relationship was plotted with the measured response signal (peak area) as a function of the analyte concentration, and linear regression was performed by the least squares method. The correlation coefficient R was reported at least 2 to confirm a good linear relationship. The linear regression coefficient R 2 should not be less than 0.990.

[0115] The results are shown in Table 4.

[0116] Table 4 Linearity and Range

[0117]

[0118]

[0119] Experimental Example 5 Precision

[0120] The experimental conditions, liquid chromatography method, and solution preparation were the same as in Experimental Example 1

[0121] Spiked test solution: Accurately weigh 20 mg of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one in a 20-ml volumetric flask, measure 0.1 ml of the stock solution of impurity H reference substance, dissolve and dilute with the mobile phase, prepare 6 portions in parallel, and inject samples successively.

[0122] The repeatability results are shown in Table 5.

[0123] Table 5 Repeatability

[0124] Sequence Impurity H 1 0.09 2 0.09 3 0.09 4 0.09 5 0.09 6 0.09 RSD% 0

[0125] Intermediate precision was carried out by the same operation method by different personnel on different instruments. The results are shown in Table 6 Table 6 Intermediate Precision

[0126]

[0127] Experimental Example 6 Accuracy

[0128] The experimental conditions, liquid chromatography method, and solution preparation were the same as in Experimental Example 1

[0129] Accuracy was obtained by adding three different concentrations of impurity H, namely 50%, 100%, and 150% of the target, to the test sample and measuring the recovery rate of impurity H. The accuracy of impurity H was the ratio (recovery rate) between the content of the known impurity H in the spiked sample and the theoretical value after adding a known amount of impurity H, expressed as a percentage %. The results are shown in Table 7.

[0130] Table 7 Accuracy

[0131]

[0132] Examples 1-2 show that the present invention can accurately determine the content of the isomer (impurity H) of the tedizolid phosphate intermediate (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one, thereby ensuring that the quality control of this intermediate meets the requirements. At the same time, the effective quality control of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one also guarantees the quality of the tedizolid phosphate API.

[0133] The research results of Experimental Examples 1 to 6 show that the method for determining impurity H of (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one in the present invention has good specificity, good precision, high accuracy and high sensitivity, and can be applied to the quality control of related substances in the synthesis of bulk drugs.

[0134] In summary, the present invention meets the requirements of the Chinese Pharmacopoeia (2020 Edition) for analytical methodology, thereby effectively controlling the quality of the tedizolid phosphate intermediate, improving the quality of the tedizolid phosphate bulk drug, and at the same time effectively monitoring the synthesis process of the tedizolid phosphate intermediate and the synthesis process of the tedizolid phosphate bulk drug.

Claims

1. A method for detecting isomers of tedizolid phosphate intermediate, characterized in that: It is detected by high performance liquid chromatography, and the specific steps are as follows: a. Preparation of test solution: Take the intermediate of tedizolid phosphate to be tested, dissolve it with the mobile phase to obtain the solution; b. Preparation of system suitability solution: Take the reference substance of the intermediate of tedizolid phosphate and its isomer reference substance respectively, dissolve them with the mobile phase, and mix to obtain the system suitability solution; c. Inject the test solution and the system suitability solution into the chromatograph respectively, and the chromatographic conditions are as follows: Chromatographic column: CHIRALPAK IA, specification 4.6×250mm, 5μm; Mobile phase: n-hexane - isopropanol - trifluoroacetic acid with a volume ratio of 50 - 80:50 - 20:0.1; Detection wavelength is 220 - 260nm; The intermediate of tedizolid phosphate is (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one; The (R)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one is provided by Sichuan Meiyu Gao Biopharmaceutical Co., Ltd.; The isomer is (S)-3-(4-bromo-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one.

2. The detection method according to claim 1, characterized in that: The mass-volume ratio of the intermediate of tedizolid phosphate to the mobile phase in step a is 0.5 - 2mg:1ml.

3. The detection method according to claim 1, wherein: In the system suitability solution in step b, the concentration of the reference substance of the intermediate of tedizolid phosphate is 0.5 - 2mg / ml, and the concentration of its isomer reference substance is 0.5 - 2μg / ml.

4. The detection method according to claim 1, characterized in that: The volume ratio of n-hexane - isopropanol - trifluoroacetic acid in step c is 60:40:0.

1.

5. The detection method according to claim 1, wherein: in the chromatographic conditions in step c, the flow rate is 0.5 - 1.5ml / min, the column temperature is 30 - 40°C, and the injection volume is 10 - 20μl.

6. The detection method according to claim 5, characterized in that: In the chromatographic conditions, the detection wavelength is 240nm, the flow rate is 1.0ml / min, the column temperature is 30°C, and the injection volume is 10μl.

7. The detection method according to claim 1, characterized in that: In the chromatogram of the test solution, there is a chromatographic peak corresponding to the chromatographic peak of the isomer in the chromatogram of the system suitability solution, that is, the test sample contains the isomer.

8. A method for determining the isomer content of tedizolid phosphate intermediate, characterized in that: The specific operation steps are as follows: 1) Detect according to the method described in any one of claims 1 - 7; 2) Calculate the content of related substances, and the calculation formula is as follows: Among them, X i %: Content of isomers in the test sample, A i : Peak area of isomers in the test sample, A: Sum of the peak areas of all peaks in the test sample solution.

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