Impurity profiling of morphine by liquid chromatography-heated electrospray ionization mass spectrometry (LC-HESI-MS)

Abstract

Separation of morphine and its impurities (related substances specified in relevant European Pharmacopoeia monographs, as well as the other naturally occurring coextracted alkaloids) was obtained within a close retention window on a reverse phase HPLC column, eluted with optimized gradient, consisting of methanol and 5 mM ammonium formate, adjusted to pH 10.2. Systematic optimization of the chromatographic conditions was carried out using design of experiments. According to their mass spectra, known and specified impurities were identified and tentative structures for unknown impurities were proposed. MS analyses were performed in positive ionization mode using heated electrospray ionization. Fragmentation patterns of the eluted compounds under optimized mass spectrometry conditions indicated that all detected impurities are structurally related to morphine.