A two-step thermochemolysis for Soil Organic Matter analysis. Application to lipid-free organic fraction and humic substances from an ombrotrophic peatland.

A two-step thermochemolysis for Soil Organic Matter analysis. Application to lipid-free organic fraction and humic substances from an ombrotrophic peatland.

Peer-reviewed article not indexed in WoS or Scopus

A two-step off-line thermochemolysis was developed to characterize successively free and bound compounds in humic fractions. Two reactants with different strengths were used: hexamethyldisilazane (HMDS) followed by tetramethylammonium hydroxide (TMAH). Analysis of the thermolysates showed obvious differences between the two steps regarding the nature and/or the distribution of the numerous identified products. The first step with HMDS revealed the occurrence of thermolabile compounds and/or molecular units occurring initially in (bio)polymers susceptible to be cracked by HMDS, mostly carbohydrates and aromatics. The second step with TMAH released products resulting from the cracking of units with a relatively high thermal and/or chemical stability (monomers from biopolymers such as lignin and cutins, suberins or waxes). Two-step thermochemolysis thus appears as an interesting tool to help deciphering the composition, origin and nature of soil and sediment organic matter. Moreover, the comparison of the three humic substances fractions (fulvic acids, humic acids and humin) shows that a part of the analysed compounds (lipids, aromatic and carbohydrates) were lost during this chemical fractionation.

A two-step off-line thermochemolysis was developed to characterize successively free and bound compounds in humic fractions. Two reactants with different strengths were used: hexamethyldisilazane (HMDS) followed by tetramethylammonium hydroxide (TMAH). Analysis of the thermolysates showed obvious differences between the two steps regarding the nature and/or the distribution of the numerous identified products. The first step with HMDS revealed the occurrence of thermolabile compounds and/or molecular units occurring initially in (bio)polymers susceptible to be cracked by HMDS, mostly carbohydrates and aromatics. The second step with TMAH released products resulting from the cracking of units with a relatively high thermal and/or chemical stability (monomers from biopolymers such as lignin and cutins, suberins or waxes). Two-step thermochemolysis thus appears as an interesting tool to help deciphering the composition, origin and nature of soil and sediment organic matter. Moreover, the comparison of the three humic substances fractions (fulvic acids, humic acids and humin) shows that a part of the analysed compounds (lipids, aromatic and carbohydrates) were lost during this chemical fractionation.

Thermochemolysis, two-step method, HMDS, TMAH, soil organic matter

Thermochemolysis, two-step method, HMDS, TMAH, soil organic matter

ESTOURNEL-PELARDY, C.; EL-MUFLEH AL HUSSEINI, A.; DOSKOČIL, L.; GRASSET, L.

2014

13.09.2013

0165-2370

JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS

104

11

Kingdom of the Netherlands

103

110

8

http://hdl.handle.net/