- Tracing compositional changes of fatty acids (FAs) is frequently used as a means of monitoring metabolic alterations in perturbed biological states. Given that more than half of FAs in the mammalian lipidome are unsaturated, quantitation of FAs at a carbon-carbon double bond (C=C) location level is necessary. The use of 2-acetylpiridine (2-acpy) as the charge-tagging PB reagent led to a limit of identification in the subnanomolar range for mono- and polyunsaturated as well as conjugated FAs. Conjugated free FAs of low abundance such as FA 18:2 (n-7, n-9) and FA 18:2 (n-6, n-8) were quantified at concentrations of 0.61 ± 0.05 and 0.05 ± 0.01 mg per 100 g in yak milk powder, respectively.
- Cerebrosides, including glucosylceramides (GlcCers) and galactosylceramides (GalCers), are important membrane components of animal cells with deficiencies resulting in devastating lysosomal storage disorders. Their quantification is essential for disease diagnosis and a better understanding of disease mechanisms. The simultaneous quantification of GlcCer and GalCer isomers is, however, particularly challenging due to their virtually identical structures. To address this challenge, we developed a new LC/MS-based method using differential ion mobility spectrometry (DMS) capable of rapidly and reproducibly separating and quantifying isomeric cerebrosides in a single run.
- Oxidized phospholipids (OxPLs) are widely held to be associated with various diseases, such as arteriosclerosis, diabetes, and cancer. To characterize the structure-specific behavior of OxPLs and their physiological relevance, we developed a comprehensive analytical method by establishing a measured MS/MS spectra library of OxPLs. Biogenic OxPLs were prepared by the addition of specific oxidized fatty acids to cultured cells, where they were incorporated into cellular phospholipids, and untargeted lipidomics by LC-quadrupole/TOF-MS was applied to collect MS/MS spectra for the OxPLs.
- Endocannabinoids, a class of lipid messengers, have emerged as crucial regulators of synaptic communication in the CNS. Dysregulation of these compounds has been implicated in many brain disorders. Although some studies have identified and quantified a limited number of target compounds, a method that provides comprehensive quantitative information on endocannabinoids and related N-acylethanolamines (NAEs) in cerebrospinal fluid (CSF) is currently lacking, as measurements are challenging due to low concentrations under normal physiological conditions.
- The aspects of cellular metabolism controlled by phosphatidylinositol phosphates (PtdInsPs) have been broadly expanded, and these phospholipids have drawn tremendous attention as pleiotropic signaling molecules. PtdInsPs analysis using LC/MS/MS has remained challenging due to the strong hydrophilicity of these lipids. Multiple reaction monitoring (MRM) or a neutral loss scan has been performed to quantitatively measure PtdInsPs after chemical derivatization on the phosphate groups of inositol moieties.