Determination of epoxide impurity in sarpogrelate hydrochloride intermediate by UHPLC and column-switching liquid chromatography

Abstract

The determination of genotoxic impurities, which is closely related to toxicological concern and daily dose, plays a key role in drug quality control. Epoxide impurity is a kind of genotoxic impurity with an epoxy ring structure during the synthesis process of sarpogrelate hydrochloride. According to the sarpogrelate hydrochloride daily dose, epoxide impurity is limited to the under 5 ppm level. The liquid chromatographic-tandem mass spectrometric (LC/MS/MS) or the gas chromatography-mass spectrometric (GC/MS) method is commonly used to characterize the epoxide impurity of sarpogrelate hydrochloride intermediates. However, these methods are not simple or economical enough to detect epoxide impurity. In this study, we resolved the problem by using the most common UV method with two ideas: one was to improve the absolute sensitivity, and the other was to reduce matrix effects. Both ultra high-performance liquid chromatography (UHPLC with high sensitivity LightPipe™ flow cells) and column-switching liquid chromatography methods were developed and validated for the quantitative determination of epoxide impurity in sarpogrelate hydrochloride intermediates. The limits of detection (LODs) of the UHPLC and column-switching liquid chromatography methods were 0.09 ppm (0.09 μg/g) and 0.33 ppm (0.33 μg/g), and the recovery rates of both methods were 87.2%–132.1% and 97.4%–100.1%, respectively. Both methods established and provided guidance for analysts to develop procedures for impurity control, especially for structures of impurity with similar matrices.