Secondary structure of humic acids. Can micelle-like conformation be proved by aqueous size exclusion chromatography?

Citation
B. Varga et al., Secondary structure of humic acids. Can micelle-like conformation be proved by aqueous size exclusion chromatography?, ENV SCI TEC, 34(15), 2000, pp. 3303-3306
Citations number
27
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Journal title
ENVIRONMENTAL SCIENCE & TECHNOLOGY
ISSN journal
0013936X → ACNP
Volume
34
Issue
15
Year of publication
2000
Pages
3303 - 3306
Database
ISI
SICI code
0013-936X(20000801)34:15<3303:SSOHAC>2.0.ZU;2-#
Abstract
Understanding the chemical and secondary structures of humic substances is essential to predict their interactions with organic and inorganic pollutan ts in the environment. Humic substances are suggested by some to form micel les under certain conditions. Disruption of the hypothesized micelle-like s tructure by the addition of organic acids was reported earlier based on obs erved retention shift in size exclusion chromatographic analyses. In this w ork the effects of added organic and inorganic acids on the retention shift are studied in humic acid samples. Parameters such as eluent pH, salt conc entration, and buffer capacity were examined simultaneously with the additi on of organic and inorganic acids to the samples. The results suggest that the retention shift was not the consequence of micellar disaggregation but secondary (mainly hydrophobic) interactions caused by the pH change on the stationary phase were responsible. Therefore, micellelike structure of humi c substances cannot be confirmed solely on the basis of the change in reten tion volumes. For the characterization of humic substances by size exclusio n chromatography secondary interactions (ionic and hydrophobic) should also be considered.