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

The reactivity of alkaloids in dehydrogenation was tion/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]center dot+, and [M + H]+ ions in alpha-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.

Automated summary

The reactivity of alkaloids in dehydrogenation was studied using mass spectrometry, and the relationship between reactivity and chemical properties/structures of alkaloids was explored. It was found that different types of alkaloids exhibited different characteristics in dehydrogenation reactions.