Investigation of potential degradation products of a newly synthesised β-lactam antibiotic by multi-stage liquid chromatography–electrospray mass spectrometry

Abstract This work describes the use of multi-stage liquid chromatography–electrospray mass spectrometry to characterise four potential degradation products associated with a suspension containing a newly synthesised β-lactam antibacterial compound. Initial identification of these degradates was obtained by analytical LC in which the mobile phase contained cetyltrimethylammonium bromide as ion-pairing agent and ammonium phosphate buffer, both of which are highly involatile making them incompatible with electrospray mass spectrometry. The use of multi-stage liquid chromatography maintained the initial LC conditions necessary for the desired separation and at the same time facilitated the use of mass spectrometry detection.