Quantification of Individual Lipid Species in Lipidomics

Many modern technologies have been used in lipidomics for quantification of lipid species in biological systems. Electrospray ionization mass spectrometry (ESI-MS) has evolved to be one of the most powerful technologies for quantitative analyses of individual lipid species. Selected ion monitoring (SIM) is an MS scanning mode in which only a single m/z or a limited number of m/z ratios is transmitted and/or detected by the instrument. This is a classic method for analysis of particular compounds or fragments of interest when mass spectrometers are predominantly constructed with a mass analyzer of single quadrupole or Fourier transform ion cyclotron resonance. To improve the specificity while retaining the high sensitivity, selected or multiple reaction monitoring (SRM/MRM) is evolved from the SIM technique, which is only focused on one m/z of a compound to the SRM that is focused on both a molecular ion and a fragment-ion resultant from the precursor ion.