CHEMICAL CHARACTERIZATION OF OZONATED LIGNIN SOLUTIONS FROM CORN (ZEA-MAYS) STALK AND POPLAR (POPULUS-DELTOIDES) WOOD BY CAPILLARY GAS-CHROMATOGRAPHY

Corn (Zea mays) stalk and poplar (Populus deltoides) wood lignin was c onverted into monomeric aromatic compounds and short chain aliphatic c arboxylic acids, The main reaction products were separated and identif ied using capillary gas chromatography-mass spectrometry on an HP-5 co lumn, The compounds were considered as positively identified when thei r mass spectra and GC retention times agreed with those of authentic s tandard samples, The quantitative estimation of the identified reactio n products was accomplished on an OV-101 capillary column by gas chrom atography-FID using the internal standard method. Among the aromatic c ompounds, aldehydes (p-hydroxybenzaldehyde, vanillin, and syringaldehy de), acids (p-hydroxybenzoic, vanillic, 3,4-dihydroxybenzoic, and syri ngic), and one phenol (hydroquinone) were determined. In addition, the aliphatic carboxylic acids: glycolic, oxalic, malonic, glyoxylic, but anedioic, glyceric, and malic acid were identified, All the calibratio n curves of the quantified compounds approximated to a straight line, For both corn stalk and poplar wood lignins, the major components were the aromatic aldehydes (71 and 64% of the characterized fraction, res pectively), followed by the aliphatic carboxylic acids (20 and 21% of the characterized fraction, respectively).