The development of methods to separate and identify variant lipid isomers, utilizing FAIMS and other technologies

Abstract

The development of lipidomics has accelerated over the last decade. However, one of the major sticking points for true identification of individual lipids is the existence of isomers. Due to the complex range of possible isomers, new techniques are required for separation and identification. This work concerns the evolution of both new methods involving FAIMS and multi-stage analytics with OzID. Coupling FAIMS to OzID allows for separation of many isomeric lipids by their movement in FAIMS space, as well as exact identification of double-bond position and geometry utilizing ozone's ability to dissociate carbon-carbon double bonds. In conjunction, the use of several different metal cations allows for near total resolution of all tested lipid species. It is concluded that, while the use of FAIMS to separate lipids is shown in detail, the use of OzID coupled to FAIMS is less firm. Due to our use of an LTQ and the inherent resolution problems experienced by doping into the collision cell, we cannot perform the experiments at the level demonstrated by collaborators on different instruments.