Comprehensive lipidomics profiling in complex real samples using hyphenated chromatography techniques coupled to mass spectrometry detection

Lipidomics, a branch of metabolomics, is a science that is based on the study of all lipids present in a biological system know as lipidome [1]. The study of lipids has assumed between the scientists considerable importance and attention with the knowledge that they are involved in many vital biological processes in humans, animals, plants and microorganisms. The scientific communities confirm that lipids play a key role as energy storage in animal and plant tissues and they are responsible for maintaining the structural integrity of cells as major components of membranes [2]. The complete characterization of lipids in human blood allows understanding the impact of dietary and lifestyle in the human health. Their dysregulation contributes to numerous diseases, such cardiovascular disease [3], diabetes [4, 5], obesity [6], cystic fibrosis [7], male and female infertility [8-10], and Alzheimer’s disease [11]. Lipids or fats are also the ingredients of foodstuff derived from both animal and plants. Fats represent almost 40% of dietary calories in developed countries, and their composition is obviously vital for a good nutrition. Dietary fats are essential for normal growth, development, and maintenance of body, and serve a number of important functions. In addition, fats contribute greatly to the palatability, taste and structure of foods [2]. Lipid samples from biological matrices are complex mixtures that require the use of chromatographic techniques for accurate identification and quantification. High performance liquid chromatography (HPLC) is usually used to separate intact lipid molecules. Lipid compounds can also be identified by their conversion with specific chemical reagents. In this case, the fatty acid (FA) composition of lipid classes is determined by gas chromatography techniques (GC). Probably, 99% of the analyses of FAs in foods are executed by using GC approach, previous derivatization of lipid compounds to corresponding fatty acid methyl esters (FAMEs) [12]. Given the complexity of the lipid matrices and the great structural diversity of these molecules, currently no single procedure is capable to separate lipid specie and a combination of LC and GC techniques must be used for a full characterization of the lipidome. The present PhD. thesis is placed into the lipidomic context. Specifically, the main aim of this research is the development of modern analytical technique, and improvement of the established methods, for the characterization of complex lipid matrices.