Analyzing Water Soluble Soil Organics as Trifluoroacetyl Derivatives by Liquid State Proton Nuclear Magnetic Resonance

Abstract

In forested ecosystems, water soluble organics play an important role in soil processes including carbon and nutrient turnover, microbial activity and pedogenesis. The quantity and quality (i.e., chemistry) of these materials is sensitive to land management practices. Monitoring alterations in the chemistry of water soluble organics resulting from land management practices is difficult because of the complexity and low concentration of these compounds. A procedure is described in which the water soluble organics are quantitatively derivatized with trifluoroacetic anhydride and then analyzed by liquid state proton nuclear magnetic resonance (¹H NMR). The procedure was applied to sample amounts as low as 0.03 mg from the forest floor and root exudates. The root exudate samples were dominated by aliphatic compounds with relatively few O‐alkyl, olefinic and aromatic compounds. The chemistry of the samples originating from the forest floor differed dramatically with soil texture and treatment combinations.

Keywords:

• Water soluble organics
• ¹H NMR
• root exudates
• acetylation

Notes

¹The use of trade or firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of Agriculture nor North Carolina State University of any product or service.