Electron capture negative chemical ionization mass spectrometry and tandem mass spectrometry analysis of β‐carotene, α‐tocopherol and their oxidation products

Abstract

AbstractThe biological antioxidants α‐tocopherol, 1, and β‐carotene, 4, and products of their antioxidant reactions are potentially important indicators of biological antioxidant status and functions. Electron capture by compounds 1 and 4 and their oxidation products yields intense molecular anions with little fragmentation. Collision‐induced dissociation of the molecular anions was studied by linked‐scaning (B/E = constant) on a reverse‐geometry magnetic‐sector mass spectrometer. Both 1 and 4 and their products undergo extensive diagnostic cleavages of their hydrocarbon chains, apparently via charge‐remote fragmentation. Electron capture negative chemical ionization mass spectrometry appears uniquely suited to structure identification studies of antioxidants and their oxidation products. This methodology is used to identify oxidation products of 1 and 4 from a model biological membrane system subjected to peroxyl radical attack.