Multimatrix Variation Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry as a Tool for Determining the Bonding of Nitrogen Atoms in Alkaloids.

ABSTRACT: The reactivity of alkaloids in dehydrogenation was investigated using multimatrix variation matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of over 20 different alkaloids with six matrices. The dehydrogenated molecular ions [M - H]⁺ generated by in-source decay were detected in the MALDI mass spectra of some types of alkaloids such as reserpine. The dehydrogenation proceeded at the cyclic tertiary amine rather than double-bonded nitrogen atoms and indole rings involved in the electron-delocalized systems. The stable protonated primary amines hindered dehydrogenation. The laser-induced dehydrogenation correlated with the chemical properties and structures of alkaloids. Alkaloids were classified into three types by the ratio of dehydrogenation by comparing the relative abundances of [M - H]⁺, [M]^•+, and [M + H]⁺ ions in α-cyano-4-hydroxycinnamic acid and 5-formylsalicylic acid matrices. Structural isomers were also discriminated by this method of analyzing the three molecular ions' ratio using multimatrix variation MALDI-MS.

SUBMITTER: Yamagaki T 

PROVIDER: S-EPMC9732872 | biostudies-literature | 2022 Dec

REPOSITORIES: biostudies-literature