Abstract :
[en] Metabolomics usually focuses on the hydrophilic chemical classes like amino acids, sugars, organic acids, and nucleotides, while lipidomics has emerged as an independent omics owing to its structural complexities and hydrophobic nature. MS-based omics technologies are widely used to profile small molecules in various matrices and provide comprehensive snapshots of cellular metabolic phenotypes. It mainly includes liquid-chromatography coupled MS, shotgun lipidomics, MS imaging, and ion mobility-based techniques. However, along with enhanced separation capacity and optimized chemical derivatization approaches, comprehensive two-dimensional gas chromatography (GC×GC) coupled to MS can also be a powerful tool in lipidomics to investigate some groups of lipids along with other metabolites.
This study reports two analytical techniques focusing respectively on blood plasma lipidome and metabolome profiling using GC×GC coupled with time of flight MS (GC×GC-TOFMS). The lipidome-specific technique is used to determine free fatty acids bound in sources, such as triglycerides in plasma, while metabolome-specific approach is used to detect fatty acid, amino acids, and non-protein nitrogen compounds.
For GC(×GC), a conversion of these compounds into more volatile and thermally stable forms is essential. For lipidomics, a two-step sample extraction and derivatization (base-catalyzed transesterification and acid-catalyzed esterification) approach was optimized using a full factorial design to improve measurement efficiency and obtain chromatographic separation of the lipids. For Metabolic profiling, the methoximation and silylation-based approach was optimized.
The analytical methods were tested on a standard mixture of unsaturated fatty acids with six double bonds, pooled human plasma, pig plasma, and NIST reference material (SRM 1950). The lipid profiles obtained demonstrate the potential value of the proposed approach to complement conventional LC-MS approaches. In the future, integration of analytical data obtained from lipidomic and metabolomic profiling should offer the expanding coverage of biological and clinical questions.
