Developing strategies for isolation of minor impurities with mass spectrometry-directed fractionation

Efficient and automated purification of new chemical entities/potential drug substances and isolation of minor impurities are important aspects of early drug discovery and development strategies, especially when combinatorial synthesis is applied. LC–MS controlled preparative LC and automated fraction collection have been developed for this purpose. The success of such an approach is greatly determined by the quality of the software controlling the application, the coordination between software and hardware, and the reliability of the hardware. The performance of a commercially-available LC–MS controlled autopurification system was evaluated by fractionating four impurities of buspirone as a model compound, eluting closely to the major component under both acidic and basic mobile-phase conditions. A purification strategy for these four components is proposed.