Molecular Understanding of a Humic Acid by Humeomic Fractionation and Benefits from Preliminary HPSEC Separation
A mild stepwise fractionation of molecular components ofa humic acid (HA) is here aimed to address the need of a systematic and reproducible method of separation and characterization of humic substances.This approach may be defined as Humeomics in analogy with genomics and is aimed at (1) characterizing natural humic molecules and (2) clarify their relations with ecosystems functions.Moreover,the same HA was further processed with High Performance Size Exclusion Chromatography (HP-SEC) in three size fractions.Both HA and its three size-fractions underwent the Humeomics chemical fractionation to extract non-covalently bound organosoluble compounds (ORG1),weakly ester-bound organosoluble (ORG2) and hydrosoluble constituents (AQU2),strongly ester-bound organosoluble components (ORG3),and final unextractable residues (RES4).Structural identification of initial and final material,separated organo-soluble and hydrosoluble fractions,and subfractions was conducted by GC-MS,HPSEC-ESI-MS (high-resolution,Orbitrap),and solid-and liquid-state NMR.GC-MS revealed in organosoluble unbound fractions the presence of both saturated and unsaturated,linear and branched,alkanoic,hydroxyalkanoic and alkandioic acids,n-alkanes,and n-alkanols.Quantization of analytes showed that:Ⅰ) the sum of compound classes in separated fractions was greater than that for the initial HA and Ⅱ) that analytical yields of identified compounds in size-fractions were invariably larger than for the unfractionated HA,thereby showing that both size exclusion and stepwise chemical fractionation increased significantly the analytical identification of humic molecules.Our results suggest this Humeomics approach as a valid path for mapping humic molecular composition and assess humus origin and formation.
Humic substances Soil organic matter Humeomics Molecular characterization
Antonio Nebbioso Alessandro Piccolo
Centro di Ricerca Interdipartimentale sulla Risonanza Magnetica Nucleare(NMR)per lAmbiente,lAgro-Alimentare ed i Nuovi Materiali(CERMANU),Università degli Studi di Napoli Federico Ⅱ,Portici,Italy
国际会议
the 16th Meeting of the International Humic Substances Society (第十六届国际腐殖物质学会大会(IHSS 16))
杭州
英文
50-53
2012-09-09（万方平台首次上网日期，不代表论文的发表时间）