Analysis of chlorophylls and their derivatives by matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry

The analysis of chlorophylls and their derivatives by matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry is described. Four matrices—sinapinic acid, a-cyano-4-hydroxycinnnamic acid, terthiophene, and 3-aminoquinoline—were examined to determine optimal conditions for analysis of the molecular mass and structure of chlorophyll a as a representative chlorophyll. Among them, terthiophene was the most efficient without releasing metal ions, although it caused fragmentation of the phytol–ester linkage. Terthiophene was useful for the analyses of chlorophyll derivatives as well as porphyrin products such as 8-deethyl-8-vinyl-chlorophyll a, pheophorbide a, pyropheophorbide a, bacteriochlorophyll a esterified phytol, and protoporphyrin IX. The current method is suitable for rapid and accurate determination of the molecular mass and structure of chlorophylls and porphyrins.