Structure elucidation of four related substances in gramicidin with liquidchromatography/mass spectrometry

A selective reversed phase liquid chromatography/mass spectrometry (LC/MSn) method is described for the identification of related substances in commer cial gramicidin samples. Mass spectral data are acquired on an LCQ ion trap mass spectrometer equipped with an electrospray interface operated in the positive and the negative ion mode. The LCQ is ideally suited for identific ation of related substances because it provides on-line LC/MSn capability. Compared with UV detection the main advantage of this hyphenated LC/MSn tec hnique is the efficient identification of novel related substances without time-consuming isolation and purification procedures. Using this method fou r novel related substances were separated and identified in a commercial sa mple. Copyright (C) 2001 John Wiley & Sons, Ltd.