Characterization of Pimavanserin Stress Degradation Products by LCMS/MS and Optimization of Green Analytical HPLC Method for Quantification of Pimavanserin and its Impurities

Green HPLC analytical procedures can quantify contaminants since they employ few hazardous chemicals and waste, reducing environmental impact and improving laboratory safety. In literature, no green analytical method reported for quantification of impurities in pimavanserin and hence this study aimed to establish green analytical method. The method comprises XBridge BEH C18 3.0 µm (100 mm × 4.6 mm) C18 column along with ethanol and 0.01 M aqueous orthophosphoric acid in 60:40 (v/v) at 0.75 mL/min flow and 249 nm wavelength. These conditions proved to be appropriate for asymmetric peak shape along with good resolution and permissible tailing. This method produces well correlated linearity in 3-18 µg/mL for pimavanserin and 0.03-0.18 µg/mL for impurities. This method exhibit a very sensitive detection limit of 0.01 µg/mL that enables precise and accurate impurity quantification at very low concentrations. All validation parameters performed and permissible results observed for both pimavanserin and impurities. Different stress conditions like acid, base, oxidative, thermal and photolytic was analyzed for pimavanserin to evaluate method effectiveness to resolve stress degradation products (DPs). The stress study identifies two distinct DPs in acid and base degradation chromatograms and was named as DP 1 and DP 2. The applicability of MSn studies and mass fragmentation confirms DP 1 as (4-fluorobenzyl)(1-methylpiperidin-4-yl)carbamic acid and DP 2 as [4-(2-methylpropoxy)benzyl]carbamic acid. The GAPI (Green Analytical Procedure Index) and AGREE (Analytical GREEnness) metric tools were employed to assess the method greenness. This proposed green method can significantly reduce the usage of hazardous solvents without losing chromatographic performance and method efficiency. This study concluded that the method is suitable for quantifying pimavanserin and its impurities along with identification of degradation products.