MATRIX-ASSISTED LASER-DESORPTION IONIZATION MASS-SPECTROMETRY OF NATURAL AND SYNTHETIC LIGNIN

Lignin is one of the components, with cellulose and hemicellulose, of cell walls in all terrestrial plants, Lignin is an amorphous, three-di mensional, polyphenolic molecule charged with the function of giving s trength and impermeability to the plant structure. The determination o f its molecular weight and structure is still problematic owing to the difficulties in isolation of lignin from the other cell wall constitu ents, The present work reports the experimental conditions for matrix- assisted laser desorption/ionization time-of-flight mass spectrometry for the characterization of different types of natural lignins and of one synthetic lignin, A nitrogen laser (lambda=337 nm) was used for io n desorption and sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid) was chosen as the best matrix for lignin analysis. Data on the molecu lar weight distribution of oligomers in lignin and information on the monomeric constituents of different types of lignin are shown.