Determination of azide genotoxic impurity in linezolid API and glucose injection by UPLC-MS/MS

A UPLC-MS/MS method was established for the determination of the genotoxic impurity (R)-5-(azidomethyl)-3-3-fluoro-4-(4-morpholinyl)phenyl-2-oxazolidinone in linezolid API and its glucose injection. Chromatographic separation was performed on a Waters Acquity UPLC HSS T3 column (100 mm × 2.1 mm, 1.8 μm) with 0.1% formic acid water-0.1% formic acid acetonitrile (60∶40) at a flow rate of 0.3 mL/min. The UPLC-MS/MS was equipped with electrospray ionization in positive ionization mode and multiple reaction monitoring mode. The results showed that the calibration curve was linear in the range of 4-12 ng/mL and the limit of quantification was 0.073 ng/mL.The average recoveries of the low, medium and high concentration (80%,100%,120% limit concentration) loading solutions were 101.14%, 100.59% and 101.47%, respectively (RSDs:0.73%, 1.10% and 0.91%, respectively).The sample solution was stable for 6 d.No genotoxic impurity of (R)-5-(Azidomethyl)-3-3-fluoro-4-(4-morpholinyl)phenyl-2-oxazolidinonewas not detected in the samples of linezolid API and its glucose injection.