TY - JOUR
T1 - Studies of structural alterations of humic acids from conifer bark residue during composting by pyrolysis-gas chromatography/mass spectrometry using tetramethylammonium hydroxide (TMAH-py-GC/MS)
AU - Fukushima, Masami
AU - Yamamoto, Mitsuo
AU - Komai, Takeshi
AU - Yamamoto, Kanako
N1 - Funding Information:
The authors are grateful for the financial support from the Nippon Steel Corporation. We also thank to Drs. S. Horiya and S. Ueda (Eco-Green Co. Ltd.,) for providing compost samples.
PY - 2009/9
Y1 - 2009/9
N2 - Pyrolysis-gas chromatography/mass spectrometry using tetramethylammonium hydroxide (TMAH-py-GC/MS) was used to characterize the humic acids (HAs) produced during the composting of conifer bark. The syringyl to guaiacyl ratios of HAs during composting were estimated from the peak area ratios for 3,4,5-trimethoxy to 3,4-dimethoxy benzene derivatives (0.11-0.50), which are characteristic of conifer species. The peak areas for nitrogen-containing and fatty acid pyrolysate compounds increased significantly during composting, indicating the degree of humification during composting. HA samples from the bark composts contained higher levels of diterpene resin acids, monoterpenes and sesquiterpenes. To investigate the species of terpenes, the HA was extracted with ethanol, and the components of the extract classified into α-HA and hymatomelanic acid (HMA) fractions, respectively. The peak areas for terpenes in the α-HA fraction were much smaller than those in the original HA, indicating that the majority of terpenes were extracted into the HMA fraction. If terpenes were to bind to HMA via unspecified interactions, no peaks would be apparent for the direct injection of HMA in ethanol into the GC/MS without pyrolysis. A comparison of the total ion chromatograms of HMA for the TMAH-py-GC/MS and GC/MS revealed that terpenes in the HA had been incorporated into polymeric structures of HMA. These results indicate that terpenes are transferred from the raw bark and incorporated into HA fractions during the composting processes.
AB - Pyrolysis-gas chromatography/mass spectrometry using tetramethylammonium hydroxide (TMAH-py-GC/MS) was used to characterize the humic acids (HAs) produced during the composting of conifer bark. The syringyl to guaiacyl ratios of HAs during composting were estimated from the peak area ratios for 3,4,5-trimethoxy to 3,4-dimethoxy benzene derivatives (0.11-0.50), which are characteristic of conifer species. The peak areas for nitrogen-containing and fatty acid pyrolysate compounds increased significantly during composting, indicating the degree of humification during composting. HA samples from the bark composts contained higher levels of diterpene resin acids, monoterpenes and sesquiterpenes. To investigate the species of terpenes, the HA was extracted with ethanol, and the components of the extract classified into α-HA and hymatomelanic acid (HMA) fractions, respectively. The peak areas for terpenes in the α-HA fraction were much smaller than those in the original HA, indicating that the majority of terpenes were extracted into the HMA fraction. If terpenes were to bind to HMA via unspecified interactions, no peaks would be apparent for the direct injection of HMA in ethanol into the GC/MS without pyrolysis. A comparison of the total ion chromatograms of HMA for the TMAH-py-GC/MS and GC/MS revealed that terpenes in the HA had been incorporated into polymeric structures of HMA. These results indicate that terpenes are transferred from the raw bark and incorporated into HA fractions during the composting processes.
KW - Compost
KW - Conifer bark
KW - Humic acid
KW - Hymatomelanic acid
KW - TMAH-pyrolysis-GC/MS
KW - Terpenes
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U2 - 10.1016/j.jaap.2009.06.005
DO - 10.1016/j.jaap.2009.06.005
M3 - Article
AN - SCOPUS:68149169023
VL - 86
SP - 200
EP - 206
JO - Journal of Analytical and Applied Pyrolysis
JF - Journal of Analytical and Applied Pyrolysis
SN - 0165-2370
IS - 1
ER -