Identifying the characteristic secondary ions of lignin polymer using ToF-SIMS.
The chemical structure of lignin, a complex, irregular polymer of phenylpropane units that occurs in plant cell walls, was investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The positive ToF-SIMS spectra of lignin isolated from pine and beech wood showed prominent secondary ions possessing guaiacyl (at m/z 137 and 151) or syringyl (at m/z 167 and 181) rings, which are the basic building units of lignin polymer. This shows that ToF-SIMS is a useful tool for lignin structural analysis. The peaks at m/z 137 and 167 were assigned as the C6-C1 ion, and the peaks at m/z 151 and 181 may be double-component, the C6-C1 ion and the C6-C2 ion. We confirmed the characteristic guaiacyl ions using a synthetic lignin model compound, dehydrogenation polymer (DHP), which was formed by polymerizing of unlabeled and deuterium-labeled coniferyl alcohols. The formation mechanism of the main secondary ions was deduced by labeling specific positions of coniferyl alcohols with a stable isotope to study the relationship between chemical structure and secondary ion formation in ToF-SIMS.
Saito
Kaori
K
Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Kato
Toshiyuki
T
Tsuji
Yukiko
Y
Fukushima
Kazuhiko
K
D003903:Deuterium; D008031:Lignin / Q000138:chemical synthesis*; D015394:Molecular Structure; D010636:Phenols / Q000032:analysis; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods*; D014197:Trees / Q000737:chemistry
D010636:Phenols; D008031:Lignin; D003903:Deuterium; C010559:coniferyl alcohol