An efficient separation and method development for the quantifying of two basic impurities of Nicergoline by reversed-phase high performance liquid chromatography using ion-pairing counter ions

A quantification method was developed for the two basic impurities, one of which is also a metabolite, of Nicergoline (NIC), by using reversed-phase high performance liquid chromatography (RP-HPLC) and diode array detector (DAD). One of these compounds,10-methoxy-6-methylergoline-8β-methanol-5-bromo-3-pyridinecarboxylate (1-DN) is the metabolite as well as the impurity whereas, the other 10-methoxy-1,6-dimethylergoline-8β-methanol-5-chloro-3-pyridinecarboxylate (5-CN) is only an impurity. The chromatographic column was Phenomenex, Luna, 5 μm, C18 (2), 250 mm × 4.6 mm. Mobile phase was 0.1 M ammonium acetate (NH4Ac) solution containing 4 mM 1-octanesulfonicacid sodium salt (OSASS) and 6 mM tetrabutylammonium hydrogen sulphate (TBAHS) (pH: 5.9)/acetonitrile (ACN) (62:38) for 1-DN and (64:36) for 5-CN. Flow rate was 1.0 mL min −1. The diode array detector was operated at 285 nm, band width: 4 nm. Linearity was obtained in the concentration range of 0.032 × 10 −5 to 3.828 × 10 −5 M, y = 116.88 x + 0.2773 ( r 2 = 0.99989); the limit of detection (LOD) and limit of quantification (LOQ) were determined as 0.012 × 10 −5 and 0.041 × 10 −5 M for 1-DN, respectively. Linearity was obtained in the concentration range of 0.034 × 10 −5 to 4.092 × 10 −5 M, y = 104.24 x + 0.7486 ( r 2 = 0.99996); (LOD) and (LOQ) were determined as 0.014 × 10 −5 and 0.046 × 10 −5 M for 5-CN, respectively. The recovery was 100.65% for 1-DN and 100.32% for 5-CN. The amount of 1-DN in 30 mg NIC was found as 209.65 μg (0.70%) and the amount of 5-CN in 30 mg NIC was found as 27.62 μg (0.09%).