A Simple and Sensitive LC-MS/MS Method for Determination and Quantification of Potential Genotoxic Impurities in the Vismodegib Active Pharmaceutical Ingredient

A rapid and sensitive LC-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitative analysis of four potential genotoxic impurities Imp-A (2-chloro-5-nitroaniline), Imp-B (1-chloro-2-iodo-4-nitrobenzene), Imp-C (1-(2-chloro-5-nitrophenyl)ethan-1-one) and Imp-D (2-chloro-5-nitrobenzoic acid) in Vismodegib API drug sample. This trace analysis was achieved on CSH C18, 15.0 cm x 3.0 mm, 1.7 micron column maintained at 45°C. Optimal mobile phase consisted of 0.05% formic acid in water was used as mobile phase A and acetonitrile used as mobile phase B in gradient mode with the flow rate of 0.5 mL/min. The developed method had the short run time of 12 minutes. Quantification of four potential genotoxic impurities were carried out using mass detection with electrospray ionization in multiple reaction monitoring mode. The method was linear in the range of 0.03 ppm to 1.50 ppm for four potential genotoxic impurities with a correlation coefficient not less than 0.999. The recoveries were found satisfactory over the range between 96.67 and 106.90% for all selected impurities. The developed method was able to quantitate all four PGIs at a concentration level of 0.03 ppm (0.03 ppm with respect to 20 mg /mL Vismodegib).