A radiochemical procedure was used to quantify carboxyl content of fulvic acid. Tritium from tritiated water exchanged with carboxyl protons in fulvic acid and were then locked into the fulvic acid structure by diazomethane methylation. Liquid scintillation counting yielded quantifiable results using 100 microgram quantities of fulvic acid. Values obtained were comparable within 2 to those obtained with a Ca(OAc)2titration procedure for carboxyl determination requiring 50 milligrams of polycarboxylate.
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