SIMULTANEOUS RESOLUTION AND DETECTION OF A DRUG SUBSTANCE, IMPURITIES, AND COUNTER ION USING A MIXED-MODE HPLC COLUMN WITH EVAPORATIVE LIGHT-SCATTERING DETECTION

An alternative approach to developing individual potency, impurity, an d counter ion methods is the simultaneous resolution and detection of the drug substance, impurities, and the counter ion in a single chroma togram. LY326315 hydrochloride was used as a model compound to demonst rate this concept. The separation was achieved using a conventional HP LC system with an Alltech mixed-mode column, a reversed phase eluant, and evaporative light scattering detection (ELSD). The mixed-mode colu mn, which has both reversed phase and ion chromatography functionaliti es (e.g. phenyl/cation, C8/anion), coupled with ELSD offers a novel ap proach to simultaneously resolving and detecting pharmaceutical compou nds and counter ions in a single chromatogram.