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Great advances in lipidomics during the last years have opened the door to a broader knowledge of oxygenated lipids. These substances are derived either from the inclusion of previously hydroxylated fatty acids in the lipid structure of sphingolipids and acyl-L-carnitines, or by enzymatic and non-enzymatic modifications (oxidized lipids) of glycerophospholipids (including cardiolipins), cholesteryl esters and cholesterol. Despite their significance in the regulation of multiple diseases such as cancer or diabetes, the number of experimentally detected oxygenated lipids remains relatively low. This is in part due to the main challenges in their analysis, which are their low natural concentrations, their wide diversity of physicochemical properties, presence of isomers, and their a priori unknown presence in the biological samples. In particular, analysis of oxidized lipids, especially peroxides, has become a daunting task in liquid chromatography coupled to mass spectrometry (LC-MS) due to their high chemical and thermal instability, and the potential for further propagation of lipid oxidation and eventual degradation. The aim of this review is to highlight the experimental conditions on sample preparation procedures, the LC-MS based analytical approaches for identification and quantification of oxygenated lipids, and their relation as potential biomarkers in diseases based on the most relevant articles published in the last five years. Regarding sample preparation, special attention has been given to antioxidants, internal standards, extraction and concentration methods, and derivatization approaches. Moreover, targeted, semi-targeted and non-targeted strategies have been discussed presenting examples. Finally, considerations on the structural identification, one of the main challenges, are presented. [Display omitted] • Recent and most relevant analytical solutions for the study of oxygenated lipids. • Targeted, semi-targeted and non-targeted LC-MS approaches. • Progenitor classes and origin of oxygenated lipids. • Software, databases, and pipelines for annotation of oxygenated lipids. • Examples of potential biomarkers. [ABSTRACT FROM AUTHOR]

Background: Mechanisms causing the onset and perpetuation of inflammation in severe allergic patients remain unknown. Our previous studies suggested that severe allergic inflammation is linked to platelet dysfunction. Methods: Platelet‐rich plasma (PRP) and platelet‐poor plasma (PPP) samples were obtained by platelet‐apheresis from severe (n = 7) and mild (n = 10) allergic patients and nonallergic subjects (n = 9) to perform platelet lipidomics by liquid chromatography coupled to mass spectrometry (LC–MS) and RNA‐seq analysis. Significant metabolites and transcripts were used to identify compromised biological pathways in the severe phenotype. Platelet and inflammation‐related proteins were quantified by Luminex. Results: Platelets from severe allergic patients were characterized by high levels of ceramides, phosphoinositols, phosphocholines, and sphingomyelins. In contrast, they showed a decrease in eicosanoid precursor levels. Biological pathway analysis performed with the significant lipids revealed the alteration of phospholipases, calcium‐dependent events, and linolenic metabolism. RNAseq confirmed mRNA overexpression of genes related to platelet activation and arachidonic acid metabolism in the severe phenotypes. Pathway analysis indicated the alteration of NOD, MAPK, TLR, TNF, and IL‐17 pathways in the severe phenotype. P‐Selectin and IL‐17AF proteins were increased in the severe phenotype. Conclusions: This study demonstrates that platelet lipid, mRNA, and protein content is different according to allergy severity. These findings suggest that platelet load is a potential source of biomarkers and a new chance for therapeutic targets in severe inflammatory pathologies. [ABSTRACT FROM AUTHOR]

• Sample preparation is simple, fast, and up to 96 samples can be processed per run. • Method was fully validated and can be applied for plasma, muscle, liver, and kidney. • The method was applied to a Residue Depletion Study of zilpaterol residues in cattle. • This is the first method that uses less than 350 mg of tissue. • The analytical running in liquid chromatography takes only 5 min of analysis. Zilpaterol is a β-agonist compound which promotes fat loss and muscle gain in cattle, providing economic benefits. However, zilpaterol residues in the animal might introduce a significant risk to humans after consumption. In the present manuscript, a highly specific, sensitive method using Selected Reaction Monitoring (SRM) in positive electrospray ionization (ESI +) mode by liquid chromatography coupled to triple quadrupole mass spectrometry (LC-MS/MS) for plasma, muscle, liver and kidney is presented. For method development, composition of the aqueous mobile phase, precipitation agent, and solid phase extraction (SPE) conditions were optimized. The method was fully validated showing a good linearity and recovery average greater than or equal to 97 % for all matrices. The method was applied to residue depletion studies in cattle after withdrawal of zilpaterol supplementation at 3, 4, 5 and 6 days showing that tissues can be consumed by humans after 4th day of zilpaterol withdrawal. [ABSTRACT FROM AUTHOR]