RESUMEN
A method of ultra flow liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) was developed to elucidate the impurity of linezolid tablets. Linezolid was subjected to forced degradation under hydrolytic (acid, base and neutral), oxidative, photolytic and thermal. The structure identification of the degradation products and the fragmentation patterns for the related impurities were analyzed. A total of four degradation impurities were characterized, impurity 1 is (S)-1-amino-3-((3-fluoro-4-morpholinophenyl)amino)propan-2-ol, impurity 2 is (S)-4-(4-(5-(acetamidomethyl)-2-oxo-oxazolidin-3-yl)-2-fluorophenyl)morpholine 4-oxide, impurity 3 is (S)-5-(aminomethyl)-3-(3-fluoro-4-morpholinophenyl)oxazolidin-2-one, impurity 4 is (R)-N-(3-((3-fluoro-4-morpholinophenyl)amino)-2-hydroxypropyl)acetamide. Acid degradation induced impurity 3 and impurity 4, base degradation induced impurity 1 and impurity 4, oxidation degradation induced impurity 2, hydrolysis degradation induced impurity 4. The study also determined calibration factor using impurity references, and the calibration factors were found to be 1.3, 1.4, 0.9 and 1.1, respectively. The toxicity of the degradation impurities was predicted by web-based prediction system. The results from this study provide an important reference in quality control and evaluation of linezolid.
RESUMEN
OBJECTIVE: To establish an LC-MS method for identification of the primary degradation impurities in domestic calcitonin salmon injections. METHODS: For the RPLC analysis., the separation was performed on Waters XTerra RP C18 column (3.0 mm × 50 mm, 3.5 μm) with linear gradient elution using 0.05% aqueous trifluoroacetic acid (A) and acetonitrile (B); the flow rate was 0.5 mL · min-1; the column temperature was 40℃; the detection wavelength was set at 220 nm. For the SEC analysis, the separation was performed on TSK GEL 2000SWxl column (7.8 mm × 300 mm, 5 μm) with mobile phase consisting of TFA-water-acetonitrile(0.05:80:20); the flow rate was 0.7 mL · min-1; the column temperature was room temperature; the detection wavelength was set at 220 nm; the main impurities were collected and identified by positive mode. RESULTS: The structures of three impurities were elucidated by RPLC-MS and SEC-MS. CONCLUSION: The results of this study can be applied in impurity profile analysis, specification research, and quality control of calcitonin salmon injections.
RESUMEN
OBJECTIVE: A phenomenon was found that the content of simvastatin decreased after simvastatin tables was strored for a longtime. But few studies focused on drug quality affected by coating. This article designed a series of experiments to explore this phenomenon. METHODS: Acceleration tests were carried out to study the effect of ingredients of coating and solvent on the stability of simvastatin. Furthermore these degradated impurities were isolated and identified. According to the structure of these impurities, mechanism of reactions was speculated. RESULTS: This study revealed that simvastatin seems like to generate simvastatin acid, dehydrated simvastatin, and simvastatin acid esters in contaction with water, ethanol and aluminum oxide, thus water, ethanol and aluminum oxide might be main reasons for degradation of simvastatin tablets. CONCLUSION: The impact of the coating material and coating solvents should be considered carefully during the screening of simvastatin coating materials.