Structural characterization of bio- and geo-macromolecules by off-line thermochemolysis with tetramethylammonium hydroxide

Structural Characterization of the Lignin in the Cortex and Pith of Elephant Grass (Pennisetum purpureum) Stems

“…Py/TMAH induces cleavage of alkyl aryl ether bonds in lignin and releases products similar to those obtained upon CuO alkaline degradation, including methylated hydroxybenzaldehydes (peaks 6, 12 and 18), hydroxyacetophenones (peaks 15 and 22) and hydroxybenzoic acids (peaks 10, 16 and 24). 13,14,49,50 As seen in Figure 2, Py/TMAH of the cortex and pith released high amounts (over 45% of the total peak area) of the fully methylated derivative of p-coumaric acid, i.e., trans-3-(4-methoxyphenyl)propenoic acid methyl ester, or methyl trans-4-O-methyl-p-coumarate (peak 23), as well as lower amounts (nearly 5% of total peak area) of the fully methylated derivative of ferulic acid, i.e., trans-3-(3,4-dimethoxyphenyl)propenoic acid methyl ester, or methyl 4-O-methyl-ferulate (peak 29). In addition to the trans-forms of methylated p-hydroxycinnamic acids, minor amounts of the cis-isomers (peaks 17 and 26) were also identified.…”

Comparative study for separation of atmospheric humic-like substance (HULIS) by ENVI-18, HLB, XAD-8 and DEAE sorbents: Elemental composition, FT-IR, 1H NMR and off-line thermochemolysis with tetramethylammonium hydroxide (TMAH)

“…The aromatic compounds identified in HULIS were remarkably similar to pyrolysis products of HAs, FAs and lignin (Martin et al, 1994(Martin et al, , 1995del Rio et al, 1998;Chefetz et al, 2002;Li et al, 2006;Fukushima et al, 2011). All HULIS pyrograms present two distinct peaks at 32.8 min and 34.5 min (Nos.…”

“…have also been detected in water soluble organic compounds in organic aerosol (Gelencser et al, 2000;Subbalakshmi et al, 2000) and in dissolved organic matter in river water or rainwater (del Rio et al, 1998). The aromatic compounds identified in HULIS were remarkably similar to pyrolysis products of HAs, FAs and lignin (Martin et al, 1994(Martin et al, , 1995del Rio et al, 1998;Chefetz et al, 2002;Li et al, 2006;Fukushima et al, 2011).…”

“…Among the aliphatic acids, monocarboxylic acids (fatty acids) with even-numbered carbon chains, such as hexadecanoic acid and octadecanoic acid, were detected in all the samples. These belong to the most common fatty acids in plant and animal lipids (Gobe et al, 2000) and are often detected in HA samples that have undergone pyrolysis (del Rio et al, 1998;Li et al, 2006). Unsaturated monocarboxylic acids, such as hexadecenoic acid and octadecenoic acid, also detected in all the samples, may have derived from vegetation emissions (Lehtonen et al, 2001).…”

Direct chemolysis–gas chromatography–mass spectrometry for analysis of paint materials

“…Since its first introduction, pyrolysis-methylation has been applied to many different biopolymers [9 -11], humic materials [12,13], whole soils [14 -15], asphaltenes, kerogens, and coals [13,16] and resins and resinites [9,17].…”