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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #293427
Title: Evaluation of a proposed standardized analytical method for the determination of humic and fulvic acids in commercial products

Author
item LAMAR, RICHARD - Earthfax Development Corporation
item Olk, Daniel - Dan
item MAYHEW, LAWRENCE - Eco Agri-Minerals
item BLOOM, PAUL - University Of Minnesota

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 10/9/2012
Publication Date: 2/4/2013
Citation: Lamar, R., Olk, D.C., Mayhew, L., Bloom, P.R. 2013. Evaluation of a proposed standardized analytical method for the determination of humic and fulvic acids in commercial products. In: Xu, J., Wu, J., He, Z., editors. Functions of Natural Organic Matter in a Changing Environment. Dordrecht, The Netherlands: Springer. p. 1071-1073.

Interpretive Summary:

Technical Abstract: A constraint to growth of the commercial humic products industry has been the lack of a widely accepted procedure for determining humic acid and fulvic acid concentrations of the products, which has raised regulatory issues. On behalf of the U.S.-based Humic Products Trade Association, we developed an improved procedure that measures humic acids and fulvic acids gravimetrically. The humic acid is isolated by the traditional acidification to pH 1 of a base extract, although solution C and salts must be diluted to specified concentration ranges. The fulvic acid is defined as the hydrophobic material that is adsorbed onto a DAX-8 resin column when the base- and acid-soluble material is passed through the column. Following separation, both the humic acid and fulvic acid fractions are oven-dried and weighed. The method has high precision, indicating good reproducibility in discriminating between humic acids and fulvic acids. This method can distinguish humic acids and fulvic acids from several potential adulterants, including amino acids and carbohydrates. However, it cannot distinguish lignosulphonates from fulvic acids.