Condensed tannins from litchi seed were analyzed using reflectron modes and linear modes of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The reflectron modes (accelerating voltage, 20.0 kV|reflectron voltage, 23.0 kV|delayed extraction voltage, 16.32 kV|lens voltage, 9.45 kV) spectra obtained clear information on basic unit, interflavan linkage and polymerization degree extended from 3-mers to 18-mers. The linear modes (accelerating voltage, 20.0 kV|delayed extraction voltage, 16.25 kV|lens voltage, 10.0 kV) spectra further expanded the detectable polymers up to 27-mers. Litchi seed condensed tannins were A-type procyanidins polymer with as high as 27-mers. In the present study, reflectron modes coupled with linear modes was discussed as a potential method of MALDI-TOF MS in characterization of condensed tannins.

Key words: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, reflectron mode, linear mode, litchi seed, condensed tannins