A method for detecting linezolid isomers

Abstract

The present invention discloses a method for detecting linezolid isomers, which uses high-performance liquid chromatography for detection. The chromatographic conditions are: a polysaccharide derivative solvent-resistant chiral chromatographic column as the stationary phase, and a mixture of acetonitrile and aqueous ammonium bicarbonate as the mobile phase. The present invention screens suitable detection conditions to enable a reversed-phase chromatography detection system that can be used for detecting isomers in linezolid injection. This avoids the influence of water in the injection on the detection system, improves the stability of the detection system, and can improve the accuracy of linezolid isomer detection, reduce interference, and increase sensitivity. The present invention can be used for the detection of isomers in linezolid raw materials and preparations thereof.

Description

Technical Field

[0001] The present invention relates to the technical field of drug detection, and in particular to a method for detecting linezolid isomers. Background Art

[0002] Linezolid is a synthetic oxazolidinone antibiotic with the chemical name (S)-N[[3-[3-fluoro-4-(4-morpholinyl)phenyl]-2-oxo-5-oxazolidinyl]methyl]-acetamide. Developed by Pfizer, Linezolid received FDA approval in 2000 for the treatment of infections caused by Gram-positive (G+) cocci, including suspected or confirmed hospital-acquired pneumonia (HAP) caused by MRSA, community-acquired pneumonia (CAP), complicated skin and skin tissue infections (SSTIs), and vancomycin-resistant enterococci (VRE). It is marketed under the brand name Zyvox.

[0003] Linezolid has a chiral center in its molecular structure and exists as a pair of optical isomers. The pharmacologically active is the levorotatory isomer, the S-configuration, known as linezolid; the dextrorotatory linezolid is the R-isomer, known as (R)-linezolid. The structural formulas of linezolid and (R)-linezolid are shown below:

[0004]

[0005] During the production process, (R)-linezolid in the linezolid API and preparations must be inspected and controlled. Currently, normal-phase chromatography is commonly used for isomer detection in the market. Normal-phase chromatography cannot tolerate solvents containing excessive amounts of water, as excessive water can elute the silica gel components in chromatographic columns (such as the CHIRALPAKAD-H column). Therefore, when using normal-phase chromatography, it is important to flush the entire liquid phase system to a water- and salt-free system. However, injections contain water. When using normal-phase chromatography to detect injections, this water content can affect the stability of the normal-phase chromatogram, damage the instrument and chromatographic column, and affect the accuracy of the test results. Summary of the Invention

[0006] Based on the technical problems existing in the background technology, the present invention proposes a method for detecting linezolid isomers. By screening suitable detection conditions, the present invention adopts a reverse-phase chromatography detection system, which can be used for the detection of isomers in linezolid injection. This avoids the influence of water in the injection on the detection system, improves the stability of the detection system, and can improve the accuracy of linezolid isomer detection, reduce interference, and increase sensitivity. The present invention can be used for the detection of isomers in linezolid raw materials and preparations thereof.

[0007] The invention provides a method for detecting linezolid isomers, which adopts a high performance liquid chromatography method for detection. The chromatographic conditions are as follows: the stationary phase is a polysaccharide derivative solvent-resistant chiral chromatographic column, and the mobile phase is a mixture of acetonitrile and ammonium bicarbonate aqueous solution.

[0008] Preferably, the filler of the polysaccharide derivative solvent-resistant chiral chromatographic column is amylose-tris(3-chloro-5-methylphenylcarbamate) covalently bonded to the surface of silica gel.

[0009] Preferably, the stationary phase is a CHIRALPAKIG chromatography column.

[0010] Preferably, the specifications of the chromatographic column are 4.6×250 mm, 5 μm.

[0011] Preferably, the volume fraction of acetonitrile in the mobile phase is 24-28%.

[0012] Preferably, the volume fraction of acetonitrile in the mobile phase may be 24%, 24.5%, 25%, 25.5%, 26%, 26.5%, 27%, 27.5% or 28%.

[0013] Preferably, the volume fraction of acetonitrile in the mobile phase is 26%.

[0014] Preferably, the concentration of the aqueous ammonium bicarbonate solution is 18-22 mmol / L.

[0015] Preferably, the concentration of the aqueous ammonium bicarbonate solution may be 18, 18.5, 19, 19.5, 20, 20.5, 21, 21.5 or 22 mmol / L.

[0016] Preferably, the pH of the aqueous ammonium bicarbonate solution is 2.8-3.2.

[0017] Preferably, the pH of the aqueous ammonium bicarbonate solution may be 2.8, 2.85, 2.9, 2.95, 3, 3.05, 3.1, 3.15 or 3.2.

[0018] Preferably, the pH of the aqueous ammonium bicarbonate solution is adjusted with phosphoric acid.

[0019] Preferably, the flow rate is 0.3-0.5 ml / min.

[0020] Preferably, the flow rate may be 0.3, 0.35, 0.4, 0.45 or 0.5 ml / min.

[0021] Preferably, an ultraviolet detector is used with a detection wavelength of 252-256 nm.

[0022] Preferably, the detection wavelength may be 252, 253, 254, 255 or 256 nm.

[0023] Preferably, the column temperature is 25-35°C.

[0024] Preferably, the column temperature may be 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 or 35°C.

[0025] Preferably, the linezolid is linezolid injection.

[0026] The present invention can be used for detecting isomers in linezolid injection, and can also be used for detecting isomers in linezolid raw materials and other preparations.

[0027] The present invention can use the main component external standard method with a correction factor to calculate the content of the isomer (i.e., (R)-linezolid) of the linezolid / linezolid preparation based on the peak area; the calculation formula is:

[0028]

[0029] Wherein, As: peak area of ​​linezolid in reference solution;

[0030] Au: peak area of ​​impurity XIV in the test solution;

[0031] Ms: weighed amount of linezolid reference substance (mg);

[0032] F: relative linezolid correction factor;

[0033] Q: Content of linezolid reference substance;

[0034] G: preparation specifications;

[0035] VS: sample sampling volume;

[0036] Vu: dilution volume of the control.

[0037] Beneficial effects

[0038] The present invention selects suitable detection conditions so that its detection system is a reverse phase chromatography, which can be used for detecting isomers in linezolid injection, avoids the influence of water in the injection on the detection system, improves the stability of the detection system, and can improve the accuracy of linezolid isomer detection with less interference. In addition, the present invention has high sensitivity, and the detection limit of the linezolid injection isomers is 0.14 ng, and the detection limit of the quantification is 0.46 ng. In addition, the present invention uses isocratic elution to further improve the system stability, the detection method is simple, and the detection results can be quickly obtained. The present invention can be used for detecting isomers in linezolid raw materials and preparations thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is the chromatogram of the diluent in Example 1.

[0040] Figure 2 It is the chromatogram of the blank auxiliary material solution in Example 1.

[0041] Figure 3 This is the chromatogram of the isomer positioning solution in Example 1.

[0042] Figure 4 This is a chromatogram of the impurity mixed solution in Example 1.

[0043] Figure 5 This is the chromatogram of the system suitability solution in Example 1.

[0044] Figure 6 It is the chromatogram of the reference substance solution in Example 1.

[0045] Figure 7 The chromatogram of the test solution in Example 1.

[0046] Figure 8 This is the chromatogram of the system suitability solution at a flow rate of 0.3 ml / min in Example 7.

[0047] Figure 9 This is the chromatogram of the system suitability solution at a flow rate of 0.5 ml / min in Example 7.

[0048] Figure 10 This is the chromatogram of the system suitability solution in Example 7 with a column temperature of 25°C.

[0049] Figure 11 This is the chromatogram of the system suitability solution in Example 7 with a column temperature of 35°C.

[0050] Figure 12 This is the chromatogram of the system suitability solution at wavelengths of 252 nm and 256 nm in Example 7.

[0051] Figure 13 The chromatograms are of the system suitability solutions for different chromatographic columns and different instruments in Example 7.

[0052] Figure 14 This is a chromatogram of the system suitability solution in Example 7 with a ratio of acetonitrile to aqueous ammonium bicarbonate solution = 24:76.

[0053] Figure 15 This is a chromatogram of the system suitability solution in Example 7 with a ratio of acetonitrile to aqueous ammonium bicarbonate solution = 28:72.

[0054] Figure 16 This is the chromatogram of the system suitability solution with an ammonium bicarbonate concentration of 18 mmol / L in Example 7.

[0055] Figure 17This is the chromatogram of the system suitability solution with an ammonium bicarbonate concentration of 22 mmol / L in Example 7.

[0056] Figure 18 This is the chromatogram of the system suitability solution with pH = 2.8 in Example 7.

[0057] Figure 19 This is the chromatogram of the system suitability solution with pH = 3.2 in Example 7. DETAILED DESCRIPTION

[0058] Hereinafter, the technical solutions of the present invention will be described in detail through specific embodiments. However, it should be clearly stated that these embodiments are provided for illustration only and are not to be construed as limiting the scope of the present invention.

[0059] The sample used in the following examples is linezolid glucose injection with a specification of 200 mg / 100 ml, and its excipients are sodium citrate dihydrate, anhydrous citric acid, and glucose monohydrate.

[0060] Example 1 (Specificity and system suitability experiment)

[0061] A method for detecting linezolid isomers is disclosed, which utilizes high performance liquid chromatography for detection. The chromatographic conditions are as follows: a CHIRALPAK IG chromatographic column (4.6×250 mm, 5 μm) as the stationary phase, acetonitrile and an aqueous ammonium bicarbonate solution (the concentration of the aqueous ammonium bicarbonate solution is 20 mmol / L, the pH is 3.0, and the pH is adjusted with phosphoric acid) as the mobile phases. The volume fraction of acetonitrile is 26%, the flow rate is 0.4 ml / min, the detection wavelength is 254 nm, the column temperature is 30° C., and the injection volume is 10 μl.

[0062] Solution preparation:

[0063] Diluent: acetonitrile-water = 26:74 v / v.

[0064] Blank excipient solution: Weigh approximately 5 ml of injection solution containing only blank excipient (equivalent to approximately 10 mg of linezolid), place in a 20 ml volumetric flask, dilute to the mark with diluent, and shake well to obtain the blank excipient solution (the blank excipients are sodium citrate dihydrate, anhydrous citric acid, and glucose monohydrate).

[0065] Reference substance stock solution: Take about 15 mg of linezolid reference substance, accurately weigh it, place it in a 100 ml volumetric flask, add diluent to dissolve and dilute to the scale, shake well, and obtain.

[0066] Reference substance solution: Accurately measure 1 ml of the reference substance stock solution, place it in a 100 ml volumetric flask, dilute to the scale with diluent, shake well, and obtain the solution (concentration is 1.5 μg / ml).

[0067] Isomer stock solution: Weigh 15 mg of isomer reference substance into a 100 ml volumetric flask, dissolve it in diluent and dilute to the mark, and shake well.

[0068] Isomer positioning solution: Pipette 1 ml of isomer stock solution into a 100 ml volumetric flask, dilute to the mark with diluent, and shake well.

[0069] System suitability solution: Pipette 1 ml of the control stock solution and 1 ml of the isomer stock solution into the same 100 ml volumetric flask, dilute to the mark with diluent, and shake well.

[0070] Impurity mixed solution: Take about 1 mg each of impurities I, II, III, IV, V, VI, VII, VIII, IX, X, and XI, place them in a 50 ml volumetric flask, add acetonitrile to dissolve and dilute to the scale, shake well, measure 1 ml and place it in a 20 ml volumetric flask, dilute to the scale with diluent, shake well, and obtain.

[0071] Test solution: Accurately pipette 5 ml of linezolid injection into a 20 ml volumetric flask, dilute to the mark with diluent, and shake well to obtain the solution (linezolid concentration is approximately 0.5 mg / ml).

[0072] The above impurity I is (S)-N-[[3-[3-fluoro-4-(4-N-morpholinyl oxide)phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide;

[0073] Impurity II is (S)-N-[[3-(4-morpholinylphenyl)-2-oxo-5-oxazolidinyl]methyl]acetamide;

[0074] Impurity III is (S)-5-(aminomethyl)-3-(3-fluoro-4-morpholinylphenyl)oxazolidin-2-one;

[0075] Impurity IV is (R)-N-[3-[(3-fluoro-4-morpholinylphenyl)amino]-2-hydroxypropyl]acetamide;

[0076] Impurity V is (S)-1-amino-3-[(3-fluoro-4-morpholinylphenyl)amino]propan-2-ol;

[0077] Impurity VI is (R)-5-(azidomethyl)-3-(3-fluoro-4-morpholinylphenyl)oxazolidin-2-one;

[0078] Impurity VII is (S)-N-[[3-(3-fluoro-4-morpholinylphenyl)-2-oxo-5-oxazolidinyl]-methyl]ethanethioamide;

[0079] Impurity VIII is (R)-N-[3-(3-fluoro-(4-morpholinyl)phenyl)-2-oxo-5-oxazolidinyl]methanesulfonic acid methyl ester;

[0080] Impurity IX is (S)-N-(3-amino-2-hydroxypropyl)-N-(3-fluoro-4-morpholinylphenyl)acetamide;

[0081] Impurity X is methyl (3-fluoro-4-morpholinylphenyl)carbamate;

[0082] Impurity XI is benzyl (4-morpholinophenyl)carbamate.

[0083] Specific operations:

[0084] Take the above diluent, blank excipient solution, isomer positioning solution, impurity mixed solution, system suitability solution, reference solution, and test solution and inject them, and record the chromatogram and test results. Figure 1-7 and as shown in Table 1.

[0085] Figure 1 is the chromatogram of the diluent in Example 1, Figure 2 is the chromatogram of the blank auxiliary material solution in Example 1, Figure 3 is the chromatogram of the isomer positioning solution in Example 1, Figure 4 is the chromatogram of the impurity mixed solution in Example 1, Figure 5 is the chromatogram of the system suitability solution in Example 1, Figure 6 is the chromatogram of the reference substance solution in Example 1, Figure 7 The chromatogram of the test solution in Example 1.

[0086] Table 1 Specificity and system suitability test results

[0087]

[0088]

[0089] From Table 1 and Figure 1-7 It can be seen that the diluent, blank excipient and mixed impurities do not interfere with the determination of linezolid enantiomers; the separation degree of linezolid and isomers in the system suitability solution is 2.23, which is greater than 1.5, and the number of theoretical plates calculated based on the enantiomer peak is 11985, which is greater than 3000, meeting the requirements; the RSD of the linezolid peak area of ​​6 consecutive injections of the reference solution is 0.6%, which is less than 10%, and the RSD of the retention time is 0.1%, which is less than 1%; the results of the specificity and system suitability experiments show that this method has good specificity and can be used as a method for the detection of isomers in linezolid and glucose injection.

[0090] Example 2 (Linearity and range experiment)

[0091] The detection conditions are the same as in Example 1.

[0092] Solution preparation:

[0093] The diluent, reference solution, system suitability solution, linezolid stock solution, and linezolid isomer stock solution were prepared according to the method of Example 1.

[0094] Linear stock solution: Pipette 5 ml of linezolid stock solution and linezolid isomer stock solution into 20 ml volumetric flasks respectively, dilute to the scale with diluent, and shake well.

[0095] Linear 1-6 series solutions: Accurately measure the linear stock solution and use diluent to prepare linear 1-6 series solutions of different concentrations.

[0096] Specific operations:

[0097] One experimenter prepared a series of linear solutions 1-6, injected them sequentially, and recorded the chromatograms. A second experimenter then prepared a new series of linear solutions 1-6, injected them, and recorded the chromatograms. The linearity results from the two experimenters were summarized, as shown in Table 2.

[0098] Table 2 Linearity results

[0099]

[0100] Note: x is the concentration and y is the peak area.

[0101] As can be seen from Table 2, linezolid and linezolid isomers have good linearity in the relative concentration range of LOQ to 0.6%, and the linear correlation coefficients of linezolid and linezolid isomers are both greater than 0.990; the linezolid isomer correction factor calculated based on the slope of linezolid and isomers is 1.0; this method has good linearity in the determination of linezolid isomers.

[0102] Example 3 (Detection limit and quantification limit experiment)

[0103] The detection conditions are the same as in Example 1.

[0104] Solution preparation:

[0105] The diluent, reference solution, and system suitability solution were prepared according to the method of Example 1.

[0106] Quantitation limit solution: Take the linear stock solution and dilute it step by step until the S / N ratio of linezolid and isomers is about 10.

[0107] Detection limit solution: Dilute the quantification limit solution to an appropriate concentration so that the S / N ratio is approximately 3.

[0108] Specific operations:

[0109] Each solution was injected into a liquid chromatograph, and the chromatogram was recorded. When the signal-to-noise ratio of linezolid and the signal-to-noise ratio of the isomers were between 8 and 20, the solution at this time was the limit of quantification solution. Six consecutive injections of the limit of quantification solution were taken to examine the RSD values ​​of the peak areas of linezolid and the isomers of linezolid injection. When the signal-to-noise ratio of linezolid and the signal-to-noise ratio of the isomers were between 2 and 8, the solution at this time was the limit of detection solution. The results are shown in Table 3.

[0110] Table 3 Results of detection limit and quantification limit

[0111]

[0112] Table 3 shows that the maximum RSD of the peak areas of linezolid and isomers in the six-injection quantification limit was 6.7%, both less than 10%. The minimum signal-to-noise ratio was 9.21, both ranging from 8 to 20. The minimum signal-to-noise ratio of linezolid and isomers in the detection limit was 3.31, both ranging from 2 to 8. The relative concentration of the quantification limit of linezolid was 0.009%, the relative concentration of the isomer quantification limit was 0.009%, the relative concentration of the detection limit of linezolid was 0.003%, and the relative concentration of the isomer quantification limit was 0.003%. This method can accurately determine the isomer quantification limit concentration and has high sensitivity. The detection limit of linezolid isomers was 0.46 ng, and the detection limit of linezolid isomers was 0.14 ng.

[0113] Example 4 (Accuracy Experiment)

[0114] The detection conditions are the same as in Example 1.

[0115] Solution preparation:

[0116] The diluent, reference solution, system suitability solution, and test solution were prepared according to the method of Example 1.

[0117] Linezolid isomer stock solution: Weigh 15 mg of linezolid isomer into a 100 ml volumetric flask, dissolve it in diluent and dilute to the mark, then shake well.

[0118] Impurity reference solution: Pipette 1 ml of linezolid isomer stock solution into a 100 ml volumetric flask, dilute to the mark with diluent, and shake well.

[0119] Accuracy stock solution: Pipette 5 ml of linezolid isomer stock solution into a 50 ml volumetric flask, dilute to the mark with diluent, and shake well.

[0120] Recovery solution: Accurately measure the test solution and the accuracy stock solution according to Table 4, dilute to the scale with diluent, shake well, and obtain.

[0121] Table 4 Recovery solution preparation method

[0122]

[0123] Specific operations:

[0124] Take the reference solution and the recovery solution separately, inject them into the liquid chromatograph, and record the chromatogram. Calculate the amount of isomers in the test sample and calculate the recovery rate. The results are shown in Table 5.

[0125] Recovery rate = (M 测 -M / M0*M 本底 ) / M 加入 ×100%; where

[0126] M 测 : Recovery rate: the amount of impurities measured in the solution in mg;

[0127] M: The amount of the test sample in the recovery solution in mg;

[0128] M0: The amount of the test sample in the 0# test solution in mg;

[0129] M 本底 :0# The amount of each impurity in the test sample in mg;

[0130] M 加入 : The amount of each impurity added in mg.

[0131] Table 5 Recovery results

[0132]

[0133] As shown in Table 5, when the relative concentration of isomers was in the range of LOQ to 0.45%, the recoveries were all between 90% and 108%, with an average recovery of 102.3%. The RSD of the recovery results was 1.3%, which was less than 10%. This method has good accuracy in determining isomers.

[0134] Example 5 (Precision and intermediate precision experiments)

[0135] The detection conditions are the same as in Example 1.

[0136] Preparation of precision solution:

[0137] The diluent, reference solution, system suitability solution, and test solution were prepared according to the method of Example 1, wherein the test solution was prepared in parallel in 6 portions.

[0138] Test spike solution: Prepare the test solution according to the 100% recovery level, and prepare 6 parallel portions.

[0139] Intermediate precision: Using the same batch of samples as the precision test, a different researcher conducted the same experiment using the same method on a different date and with different equipment. The results are shown in Table 6.

[0140] Table 6 Precision and intermediate precision results

[0141]

[0142] As shown in Table 6, the RSDs of the isomer contents in the 6 spiked samples in the precision and intermediate precision were 0.3% and 0.2%, respectively, both less than 10%; the RSD of the isomer contents in the 12 spiked samples was 1.38%, less than 10%; this method has good precision in determining isomers.

[0143] Example 6 (Solution Stability Experiment)

[0144] The detection conditions are the same as in Example 1.

[0145] Solution preparation:

[0146] The diluent, reference solution, system suitability solution, and test solution were prepared according to the method of Example 1.

[0147] Spiked test solution: Prepare the test solution according to the 100% recovery level.

[0148] Specific operations:

[0149] The reference solution, test solution and spiked test solution were placed at room temperature and samples were taken for determination at different time points.

[0150] Requirements: The peak area of ​​the reference solution at different time points should not exceed 10% compared with 0h. In the spiked test solution, the change in the isomer peak area at different time points should not exceed 10% compared with 0h. The RD of the isomer impurity peak area should not exceed 10% compared with 0h. Otherwise, the stability will return to the previous time point. The test results are shown in Table 7.

[0151] Table 7 Solution stability results

[0152]

[0153]

[0154] As shown in Table 7, the reference solution was stable for 51 days at 2-8°C, and the spiked test solution was stable for 80 hours at room temperature. No isomers were detected in the test solution at room temperature for 84 hours.

[0155] Example 7 (Durability Test)

[0156] Solution preparation:

[0157] The diluent, blank excipient solution, impurity mixed solution, system suitability solution, reference solution, and test solution were prepared according to the method of Example 1.

[0158] Spiked test solution: Prepare the test solution according to the 100% recovery level.

[0159] Specific operations:

[0160] Different chromatographic conditions were obtained by adjusting different mobile phase ratios, flow rates, column temperatures, pH values, and ammonium bicarbonate concentrations to determine the content of isomers in the spiked test solution. The RD values ​​of the isomer content were calculated by comparing with the precision or intermediate precision results, and the separation was examined at the same time.

[0161] Requirements: The separation degree of linezolid and isomers should be greater than 1.5, and the number of theoretical plates calculated based on enantiomers should be no less than 3000; the results of different chromatographic conditions are compared with the precision and intermediate precision results, and the RD of the isomer content shall not exceed 10%. The test results are shown in Table 8 and Figure 8-19 shown.

[0162] Figure 8 This is the chromatogram of the system suitability solution at a flow rate of 0.3 ml / min in Example 7; Figure 9 This is the chromatogram of the system suitability solution at a flow rate of 0.5 ml / min in Example 7; Figure 10 This is the chromatogram of the system suitability solution in Example 7 at a column temperature of 25°C; Figure 11 This is the chromatogram of the system suitability solution at a column temperature of 35° C. in Example 7; Figure 12 The chromatograms of the system suitability solutions at wavelengths of 252 nm and 256 nm in Example 7 are shown; Figure 13 The chromatograms of the system suitability solutions for different chromatographic columns and different instruments in Example 7 are shown; Figure 14 This is a chromatogram of the system suitability solution of acetonitrile:ammonium bicarbonate aqueous solution = 24:76 in Example 7; Figure 15 This is a chromatogram of the system suitability solution of acetonitrile:ammonium bicarbonate aqueous solution = 28:72 in Example 7; Figure 16 This is a chromatogram of the system suitability solution with an ammonium bicarbonate concentration of 18 mmol / L in Example 7; Figure 17 This is a chromatogram of the system suitability solution with an ammonium bicarbonate concentration of 22 mmol / L in Example 7; Figure 18 This is the chromatogram of the system suitability solution with pH = 2.8 in Example 7; Figure 19 This is the chromatogram of the system suitability solution with pH = 3.2 in Example 7.

[0163] Table 8 Durability results

[0164]

[0165]

[0166] Note: 1. Only one of the chromatographic conditions was changed, and the other conditions were the same as those in Example 1.

[0167] 2. Different chromatographic columns and different instruments: different chromatographic columns are replaced and tested simultaneously on another instrument. Other conditions are the same as the chromatographic conditions in Example 1; the chromatographic column (S02-SPZ-277) is of the same type as the chromatographic column in Example 1, but has a different batch number.

[0168] From Table 8 and Figure 8-19 It can be seen that under all conditions, the diluent, blank excipient, and impurity mixed solution did not interfere with the isomer detection; the minimum separation degree of linezolid and isomers in the system suitability solution was 1.86 (all greater than 1.5); the minimum theoretical plate number calculated based on isomers was 8822 (all greater than 3000).

[0169] Therefore, the flow rate changes within the range of 0.3ml / min to 0.5ml / min, the column temperature changes within the range of 25℃ to 35℃, the ratio of acetonitrile and ammonium bicarbonate aqueous solution in the mobile phase changes within the range of 28:72 to 24:76, the ammonium bicarbonate concentration changes within the range of 18mmol / L to 22mmol / L, and the pH of the ammonium bicarbonate aqueous solution changes within the range of 2.8 to 3.2 do not affect the isomer determination; this method has good durability in determining isomers.

[0170] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for detecting linezolid isomers, characterized in that: The detection was carried out by high performance liquid chromatography, and the chromatographic conditions were as follows: the stationary phase was a CHIRALPAK IG column, and the mobile phase was a mixture of acetonitrile and aqueous ammonium bicarbonate solution; The specifications of the chromatographic column are 4.6 × 250 mm, 5 μm; In the mobile phase, the volume fraction of acetonitrile is 24-28%; The concentration of the ammonium bicarbonate aqueous solution is 18-22 mmol / L; The pH of aqueous ammonium bicarbonate solution is 2.8-3.2; Adjust the pH of the aqueous ammonium bicarbonate solution with phosphoric acid; Flow rate is 0.3-0.5 ml / min; A UV detector was used with a detection wavelength of 252-256 nm; The column temperature was 25-35°C.

2. The method for detecting linezolid isomers according to claim 1, characterized in that: The linezolid is linezolid injection.

Images