UPLC Method for Determination of Eight Flupirtine Impurities in Bulk Substance and Their Characterization by 1H NMR and ESI–MS

Abstract

A novel and simple ultra performance liquid chromatography (UPLC) method was developed for the simultaneous quantification of flupirtine and its related impurities in active pharmaceutical ingredient. The analysis was carried out on Waters Acquity UPLC high strength silica C18 (100 × 2.1 mm) 1.8 µm column with 0.19 mL min−1 flow rate in gradient mode at 347 nm wavelength. The elution of all nine components was established within 30 min. The retention time of the flupirtine peak was observed at about 7 min. The proposed method was validated as per the current international conference on harmonization guidelines for specificity, precision, linearity, accuracy, range, limit of detection, limit of quantification, robustness and solution stability parameters. The exhaustive method study was performed to indicate the stability-indicating nature of the method. Furthermore, the work has been extended to the characterization of flupirtine and its related impurities by using proton nuclear magnetic resonance spectroscopy and electron source ionization mass spectroscopy.