QUANTITATIVE DETERMINATION OF METHYL-4-CHLOROBUTYRATE, A POTENTIAL GENOTOXIC IMPURITY, CONTENT IN MOXIFLOXACIN HCL BY GC-EI-MS

Abstract

Objective: Methyl-4-Chlorobutyrate (M4CB), a genotoxic impurity, was identified in the active pharmacological components of the fourth-generation fluoroquinolone, moxifloxacin (MXFN). There has not yet been a report on the analysis of the M4CB impurity content in the MXFN molecule. Consequently, a Gas Chromatography-Electron Ionization-Mass Spectrometry (GC-EI-MS) method was established that has the ability to identify and measure M4CB impurity content at ppm level. Methods: The column exploited in M4CB impurity assay was a Dura Bond 624 (DB-624) type stationary column. Temperatures of 220 °C and 280 °C were consistently maintained at the injection and detection sites, respectively. The helium, as carrier gas, in split mode with ratio of 1:7 was used. The column's flow rate remained steady around 2.0 ml/min. The mass spectrometer was operated in Single Ion Monitoring (SIM) mode at m/z = 74. Results: The impurity M4CB is generated during the manufacturing process of cyclopropanamine, which is an intermediary molecule in the manufacturing process of MXFN. This new GC-EI-MS approach can measure the M4CB at 0.9452 ppm in MXFN samples with a 500 mg/ml concentration following International Council for Harmonisation (ICH) standards. Very low quantification limits (0.9452 ppm), high linearity (range=0.945 ppm to 5.625 ppm; regression coefficient= 0.9999), and a reasonable recovery range (94.60-94.63%) were all provided by this new validated GC-EI-MS approach. Three batches were analysed for M4CB content by new GC-EI-MS approach and found that none of the batches contained M4CB impurity. Conclusion: The GC-EI-MS approach has excellent applicability in the quality assurance testing of MXFN for M4CB content since it was adequate in terms of linearity, precision, sensitivity, accuracy, specificity, and robustness.