, Volume 98, Issue 1, pp 7–13 | Cite as

Isolation and fractionation of soil humin using alkaline urea and dimethylsulphoxide plus sulphuric acid

  • Guixue SongEmail author
  • Michael H. B. HayesEmail author
  • Etelvino H. Novotny
  • Andre J. Simpson
Short Communication


Humin, the most recalcitrant and abundant organic fraction of soils and of sediments, is a significant contributor to the stable carbon pool in soils and is important for the global carbon budget. It has significant resistance to transformations by microorganisms. Based on the classical operational definition, humin can include any humic-type substance that is not soluble in water at any pH. We demonstrate in this study how sequential exhaustive extractions with 0.1 M sodium hydroxide (NaOH) + 6 M urea, followed by dimethylsulphoxide (DMSO) + 6% (v/v) sulphuric acid (H2SO4) solvent systems, can extract 70–80% of the residual materials remaining after prior exhaustive extractions in neutral and aqueous basic media. Solid-state 13C NMR spectra have shown that the components isolated in the base + urea system were compositionally similar to the humic and fulvic acid fractions isolated at pH 12.6 in the aqueous media. The NMR spectra indicated that the major components isolated in the DMSO + H2SO4 medium had aliphatic hydrocarbon associated with carboxyl functionalities and with lesser amounts of carbohydrate and peptide and minor amounts of lignin-derived components. The major components will have significant contributions from long-chain fatty acids, waxes, to cuticular materials. The isolates in the DMSO + H2SO4 medium were compositionally similar to the organic components that resisted solvation and remained associated with the soil clays. It is concluded that the base + urea system released humic and fulvic acids held by hydrogen bonding or by entrapment within the humin matrix. The recalcitrant humin materials extracted in DMSO + H2SO4 are largely biological molecules (from plants and the soil microbial population) that are likely to be protected from degradation by their hydrophobic moieties and by sorption on the soil clays. Thus, the major components of humin do not satisfy the classical definitions for humic substances which emphasise that these arise from microbial or chemical transformations in soils of the components of organic debris.


Soil humin Soil organic matter Urea DMSO extraction methodology 13C NMR 



The authors acknowledge support from the Science Foundation Ireland (SFI), the Environmental Protection Agency (EPA) Ireland, and the Irish Research Council for Science, Engineering and Technology (IRCSET).


  1. Aiken GR, McKnight DM, Wershaw RL, MacCarthy P (1985) In: Aiken GR, McKnight DM, Wershaw RL, MacCarthy P (eds) Humic substances in soil, sediment, and water: geochemistry, isolation, and characterization. Wiley, New York, pp 1–9Google Scholar
  2. Clapp CE, Hayes MHB (1996) Isolation of humic substance from an agriculture soil using a sequential and exhaustive extraction process. In: Clapp CE, Hayes MHB, Senesi N, Griffith SM (eds) Humic substances and organic matter in soil and water environments: characterization, transformations and interactions. International Humic Substances Society, St. Paul, pp 3–11Google Scholar
  3. Clapp CE, Hayes MHB (1999) Characterization of humic substances isolated from clay- and silt-sized fractions of a corn residue-amended agricultural soil. Soil Sci 164:899–913CrossRefGoogle Scholar
  4. Clapp CE, Hayes MHB, Simpson AJ, Kingery WL (2005) Chemistry of soil organic matter. In: Tabatabai MA, Sparks DL (eds) Chemical processes in soils, special publication no. 8. Soil Science Society of America, Madison, pp 1–150Google Scholar
  5. Deshmukh AP, Simpson AJ, Hadad CM, Hatcher PG (2005) Insights into the structure of cutin and cutan from Agave americana leaf cuticle using HR-MAS NMR spectroscopy. Org Geochem 36:1072–1085CrossRefGoogle Scholar
  6. Greenwood NN, Earnshaw A (1997) Chemistry of the elements, 2nd edn. Butterworth-Heinemann, OxfordGoogle Scholar
  7. Hayes MHB (1985) Extraction of humic substances from soil. In: Aiken GR, McKnight DM, Wershaw RL, MacCarthy P (eds) Humic substances in soil, sediment, and water: geochemistry, isolation, and characterization. Wiley, New York, pp 329–362Google Scholar
  8. Hayes MHB (2006) Solvent systems for the isolation of organic components from soils. Soil Sci Soc Am J 70:986–994CrossRefGoogle Scholar
  9. Hayes MHB, Swift RS, Wardle RE, Brown JK (1975) Humic materials from an organic soil: a comparison of extractants and of properties of extracts. Geoderma 13:231–245CrossRefGoogle Scholar
  10. Hayes TM, Hayes MHB, Skjemstad JO, Swift RS (2008) Compositional relationships between organic matter in a grassland soil and its drainage waters. Eur J Soil Sci 59:603–616CrossRefGoogle Scholar
  11. Hu WG, Mao J, Xing B, Schmidt-Rohr K (2000) Poly(methylene) crystallites in humic substances detected by nuclear magnetic resonance. Environ Sci Technol 34:530–534CrossRefGoogle Scholar
  12. Kelleher BP, Simpson AJ (2006) Humic substances in soils: are they really chemically distinct? Environ Sci Technol 40:4605–4611CrossRefPubMedGoogle Scholar
  13. Kelleher BP, Simpson MJ, Simpson AJ (2006) Assessing the fate and transformation of plant residues in the terrestrial environment using HR-MAS NMR spectroscopy. Geochim Cosmochim Acta 70:4080–4094CrossRefGoogle Scholar
  14. Knicker H, DelRio JC, Hatcher PG, Minard RD (2001) Identification of protein remnants in insoluble geopolymers using TMAH thermochemolysis/GC-MS. Org Geochem 32:397–409CrossRefGoogle Scholar
  15. Lichtfouse E, Chenu C, Baudin F, Leblond C, Da Silva M, Behar F, Derenne S, Largeau C, Wehrung P, Albrecht P (1998a) A novel pathway of soil organic matter formation by selective preservation of resistant straight-chain biopolymers: chemical and isotope evidence. Org Geochem 28:411–415CrossRefGoogle Scholar
  16. Lichtfouse E, Wehrung P, Albrecht P (1998b) Plant wax n-alkanes trapped in soil humin by noncovalent bonds. Naturwissenschaften 85:449–452CrossRefGoogle Scholar
  17. Lorenz K, Lal R, Preston CM, Nierop KGJ (2007) Strengthening the soil organic carbon pool by increasing contributions from recalcitrant aliphatic bio(macro)molecules. Geoderma 142:1–10CrossRefGoogle Scholar
  18. Malcolm RL, MacCarthy P (1992) Quantitative evaluation of XAD-8 and XAD-4 resins used in tandem for removing organic solutes from water. Environ Int 18:597–607CrossRefGoogle Scholar
  19. Novotny EH, Hayes MHB, deAevedo ER, Bonagamba TJ (2006) Characterisation of black carbon-rich samples by 13C solid-state nuclear magnetic resonance. Naturwissenschaften 93:447–450CrossRefPubMedGoogle Scholar
  20. Novotny EH, deAzevedo ER, Bonagamba TJ, Cunha TJF, Madari BE, Benites VD, Hayes MHB (2007) Studies of the compositions of humic acids from Amazonian dark earth soils. Environ Sci Technol 41:400–405CrossRefPubMedGoogle Scholar
  21. Oh-Ishi M, Maeda T (2002) Separation techniques for high-molecular-mass proteins. J Chrom B 771:49–66CrossRefGoogle Scholar
  22. Peuravuori J, Lepane V, Lehtonen T, Pihlaja K (2004) Comparative study of separation of aquatic humic substances by capillary zone electrophoresis using uncoated, polymer coated and gel filled capillaries. J Chromatography A 1023:129–142CrossRefGoogle Scholar
  23. Piccolo A (2001) The supramolecular structure of humic substances. Soil Sci 166:810–832CrossRefGoogle Scholar
  24. Piccolo A, Conte P, Trivellone E, van Lagen B, Buurman P (2002) Reduced heterogeneity of a lignite humic acid by preparative HPSEC following interaction with an organic acid. Characterization of size-separates by Pyr-GC-MS and 1H-NMR spectroscopy. Environ Sci Technol 36:76–84CrossRefPubMedGoogle Scholar
  25. Rice JA (2001) Humin Soil Sci 166:848–857CrossRefGoogle Scholar
  26. Rice JA, MacCarthy P (1988) Comments on the literature of the humin fraction of humus. Geoderma 43:65–73CrossRefGoogle Scholar
  27. Rice JA, MacCarthy P (1992) Disaggregation and characterization of humin. Sci Total Environ 117(118):83–88Google Scholar
  28. Simpson AJ, Kingery WL, Hayes MHB, Spraul M, Humpfer E, Dvortsak P, Kerssebaum R, Godejohann M, Hofmann M (2002) Molecular structures and associations of humic substances in the terrestrial environment. Naturwissenschaften 89:84–88CrossRefPubMedGoogle Scholar
  29. Simpson AJ, Kingery WL, Hatcher PG (2003) The identification of plant derived structures in humic materials using three-dimensional NMR spectroscopy. Environ Sci Technol 37:337–342CrossRefPubMedGoogle Scholar
  30. Simpson AJ, Simpson MJ, Smith E, Kelleher BP (2007a) Microbially derived inputs to soil organic matter: are current estimates too low? Environ Sci Technol 41:8070–8076CrossRefPubMedGoogle Scholar
  31. Simpson AJ, Song G, Smith E, Lam B, Novotny EH, Hayes MHB (2007b) Unravelling the structural components of soil humin by use of solution-state nuclear magnetic resonance spectroscopy. Environ Sci Technol 41:876–883CrossRefPubMedGoogle Scholar
  32. Song G, Novotny EH, Simpson AJ, Clapp CE, Hayes MHB (2008) Sequential exhaustive extraction and characterizations, by solid and solution state NMR, of the humic, including humin, components in exhaustive extracts from a Mollisol soil. Eur J Soil Sci 59:505–516CrossRefGoogle Scholar
  33. Spaccini R, Piccolo A, Haberhauer G, Gerzabek MH (2000) Transformation of organic matter from maize residues into labile and humic fractions of three European soils as revealed by 13C distribution and CPMAS-NMR spectra. Eur J Soil Sci 51:583–594Google Scholar
  34. Stevenson FJ (1994) Humus chemistry; genesis, composition, reaction, 2nd edn. Wiley, NYGoogle Scholar
  35. Swift RS (1996) Organic matter characterization. In: Sparks DL (ed) Methods of soil analysis. Part 3. Chemical methods. Soil Science Society of America and American Society of Agronomy, Madison, pp 1011–1069Google Scholar
  36. Tobi D, Elber R, Thirumalai D (2003) The dominant interaction between peptide and urea is electrostatic in nature: a molecular dynamics simulation study. Biopolymers 68:359–369CrossRefPubMedGoogle Scholar
  37. Tsutsuki K, Kuwatsuka S (1992) Characterization of humin-metal complexes in a buried volcanic ash soil profile and a peat soil. Soil Sci Plant Nutr 38:297–306Google Scholar
  38. Wang K, Xing B (2005) Chemical extractions affect the structure and phenanthrene sorption of soil humin. Environ Sci Technol 39(21):8333–8340CrossRefPubMedGoogle Scholar
  39. Zhang D, Lu S (1987) An assessment of the separation and analysis of humic substances by isoelectric focusing (IEF) method. Sci Total Environ 62:89–96CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Department of Chemical and Environmental SciencesUniversity of LimerickLimerickIreland
  2. 2.Embrapa SolosRio de JaneiroBrazil
  3. 3.Department of Chemistry, Scarborough CollegeUniversity of TorontoTorontoCanada
  4. 4.School of Sustainable Engineering and the Built EnvironmentArizona State UniversityTempeUSA

Personalised recommendations