Related Experiment Video
Updated: Jun 28, 2026
12:55
Quantification of Humic and Fulvic Acids in Humate Ores, DOC, Humified Materials and Humic Substance-Containing Commercial Products
Published on: March 18, 2022
Conductometric characterization of dissolved humic materials
Jeremy Riggle1, Ray von Wandruszka
1Department of Chemistry, University of Idaho, Moscow, ID 83844-2343, USA.
Talanta
|October 31, 2008
Summary
Conductometric titrations reveal that the slope of humic and fulvic acid protonation correlates with polyanion size and electrophoretic mobility. This method offers a way to estimate the dimensions of these complex organic molecules.
Area of Science:
- Environmental Chemistry
- Physical Chemistry
- Soil Science
Background:
- Humic and fulvic acids are complex natural organic macromolecules found in soil and aquatic environments.
- Understanding their size and structure is crucial for comprehending their behavior and interactions.
Purpose of the Study:
- To investigate the relationship between conductometric titration parameters and the dimensions of humic and fulvic acid aggregates.
- To explore the utility of conductometric titrations for estimating the size of these polyanions.
Main Methods:
- Conductometric replacement titrations were performed on humic and fulvic acids in a hydroxide solution using standard acid.
- Electrophoretic mobility measurements were correlated with the slope of the titration curves.
Main Results:
- A qualitative agreement was observed between the estimated sizes of humic/fulvic acid species and their conductance slopes.
- Fractionation and size reduction (via photolysis and sonication) of humic substances resulted in a decreased slope, as expected.
- A slight decrease in slope during titration was attributed to the contraction of humic aggregates.
Conclusions:
- Conductometric titration slopes can serve as indicators of polyanion dimensions and electrophoretic mobility.
- This technique provides a viable method for qualitatively assessing the size of humic and fulvic acid aggregates.
- The study highlights the dynamic nature of humic aggregates, showing contraction during titration.
