title: Molecular size fractionation of soil humic acids using preparative high performance size-exclusion chromatography.
abstract: High performance size-exclusion chromatography (HPSEC) is useful for the molecular size separation of soil humic acids (HAs), but there is no method available for various HAs with different chemical properties. In this paper the authors propose a new preparative HPSEC method for various soil HAs. Three soil HAs with different chemical properties were fractionated by a Shodex OHpak SB-2004 HQ column with 10mM sodium phosphate buffer (pH 7.0)/acetonitrile (3:1, v/v) as an eluent. The HAs eluted within a reasonable column range time (12-25 min) without peak tailing. Preparative HPSEC chromatograms of these HAs indicated that non-size-exclusion effects were suppressed. The separated fractions were analyzed by HPSEC to determine their apparent molecular weights. These decreased sequentially from fraction 1 to fraction 10, suggesting that the HAs had been separated by their molecular size. The size-separated fractions of the soil HA were mixed to compare them with unfractionated HA. The analytical HPSEC chromatogram of the mixed HA was almost identical to that of the unfractionated HA. It appears that the HAs do not adsorb specifically to the column during preparative HPSEC. Our preparative HPSEC method allows for rapid and reproducible separation of various soil HAs by molecular size.
authors.affiliation: The Graduate School of Science and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Daichi
authors.initials: D
authors.lastname: Asakawa
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Iimura
authors.forename: Takuro
authors.initials: T
authors.lastname: Kiyota
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Yanagi
authors.forename: Nobuhide
authors.initials: N
authors.lastname: Fujitake
mesh_terms: D002850:Chromatography, Gel / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006812:Humic Substances / Q000032:analysis*; D008970:Molecular Weight; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D006812:Humic Substances