Structural elucidation, Identification, quantization of process related impurity in Hydralazine Hydrochloride HR/AM- LC MS/MS, NMR and FTIR technique

Abstract

Major process related unknown impurity associated with the synthesis of Hydralazine hydrochloride bulk drug was detected by high performance liquid chromatography (HPLC) and was subjected to high resolution accurate liquid chromatography mass spectroscopy (HR/AM-LCMS) for identification. The proposed impurity was isolated from Hydralazine hydrochloride active pharmaceutical ingredient (API) by preparative chromatographic method and was injected on HPLC for comparison of retention time with that of the unknown process related impurity in Hydralazine hydrochloride. The molecular ion peak of preparatively isolated impurity and that of unknown process related impurity in Hydralazine hydrochloride were compared for confirmation. The postulated structure was unambiguously confirmed with the help of HR/AM- LC MS/MS, NMR and FTIR data proposed to be 1-(2-phthalazin-1-ylhydrazino)phthalazine (Hazh Dimer). This impurity of Hydralazine hydrochloride is not been previously reported. A rapid Acquity H-class gradient method with runtime of 15.0min was developed for Quantitation on Unisphere Cyno column and validated for parameters such as accuracy, precision, linearity and range, robustness. The LOD and LOQ of method were 0081% and 0.0246% respectively.