Pinpointing Double Bonds in Lipids by Paternò-Büchi Reactions and Mass Spectrometry

The positions of double bonds in lipids play critical roles in their biochemical and biophysical properties. In this study, by coupling Paternò–Büchi (P-B) reaction with tandem mass spectrometry, we developed a novel method that can achieve confident, fast, and sensitive determination of double bond locations within various types of lipids. The P-B reaction is facilitated by UV irradiation of a nanoelectrospray plume entraining lipids and acetone. Tandem mass spectrometry of the on-line reaction products via collision activation leads to the rupture of oxetane rings and the formation of diagnostic ions specific to the double bond location.

• This study introduces a novel analytical method for confident, fast and sensitive determination of lipid C=C locations by combining the Paterno-Büchi (PB) reaction with tandem mass spectrometry (PB-MS/MS).
• This method works across various types of lipids including fatty acids and phospholipids, and can be applied to complex mixture analysis (e.g., yeast extracts), with using simple experimental setup, inexpensive derivatizing reagent and no need for MS instrument modifications.
• This work establishes PB-MS/MS as a powerful tool for “deep lipidomics,” uncovering structural details critical to understanding lipid biology.