Rapid discrimination of archaeal tetraether lipid cores by liquid chromatography-tandem mass spectrometry

Atmospheric pressure chemical ionization liquid chromatography-tandem mass spectrometry (APCI LC-MS/MS) of tetraether lipid cores of archaeal origin reveals distinct dissociation pathways for three classes of core lipid extracted from Methanobacter thermautotrophicus. Within these classes, two isobaric tetraether lipids, one a scarcely reported lipid constituent of M. thermautotrophicus and the other an artefact formed during extraction from cultured cells, were identified and distinguished via their MS(2) spectra. APCI LC-MS/MS discriminates different tetraether core lipid types and isobaric species and reveals the mass of the constituent biphytanyl chains within the tetraether cores, albeit without full elucidation of their structures. Furthermore, the method allows direct estimation of the relative proportions of tetraether core lipids from chromatographic peak area measurement, allowing rapid profiling of these compounds in microbiological and environmental extracts.