A stability-indicating LC-MS/MS method optimization for Pemetrexed through design of experiments: Identification and...

A stability-indicating high-performance liquid chromatography method for Pemetrexed bulk was developed and validated as per the ICH guidelines by employing design of experiments methodology equipped with Box-Behnken design. The separation of Pemetrexed and its oxidative degradation product was achieved in isocratic elution mode with Zorbax C₁₈ column (150 mm x 4.6 mm x5 μm) using 10 mM ammonium acetate (pH 4.5 adjusted with acetic acid) and acetonitrile in the ratio of 50:50, v/v with a flow rate of 1.0 mL/min at detection wavelength of 223 nm. Tandem mass spectrometry method was adopted to identify and characterize the major oxidative degradation product. The results obtained indicate that the method is specific, linear, precise and accurate for the determination of Pemetrexed and characterization of degradation product.