The objective of this work was to develop and validate a simple derivatization and liquid–liquid extraction (LLE) procedure for GC-MS analysis of 2,4-Dichlorobutanoic acidor 2,4-Dichlorobutyric acidin Levetiracetam drug substance. The analyte was treated with methanol sulfuric acid mixture and extracted by water and n-Hexane, the supernatant allowed to separate into two phases, the derivative of analyte separated into the upper layer and detected by gas chromatography-mass spectrometry by using a short mid-polar capillary GC column at a high column-head pressure. Total run time of the analysis was15 min. Chromatographic conditions were achieved on DB-624 (6% cyanopropylphenyl and 94% dimethylpolysiloxane copolymer) capillary column (30 m long, 0.32 mm internal diameter, 1.8 μm diameter) using helium as a carrier gas at a flow rate of 1.5 mL/min.The process was optimized by a design of experiments.
Method validation parameters achieved as per regulatory requirements. The method was validated showing that the detection limit and quantitation limit of this impurity were 0.05 μg/g and 0.14 μg/g respectively. A good linearity over the 0.14-0.72 μg/g concentration range with correlation coefficient ?? 0.999, providing satisfactory results in terms of intra-day and inter-day precision as well as an optimal accuracy.
Thus, proving that thedescribed GC-MS method could be employed for fast and simple analysis ofgenotoxic impurity 2,4-Dichlorobutanoic acid in Levetiracetam drug substance.