IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 BOOK OF ABSTRACTS 42 Analysis and Characterization Monday, 24 August 2026 / Hall B+C SL15 Use of a Spectrophotometric Method for the Detection of Adulterants in Commercial Fulvic Acid Products Elena A Vialykh2,3, Jarrod Psutka1, Shelby Buckley2, Julia Gentile2, Fernando L Rosario-Ortiz2,4, Richard T Lamar5, Mohammad Rahbari1 1 BioLiNE Corporation, Alvinston, ON N0N-1A0, Canada. jpsutka@biolinecorp.ca 2 University of Colorado Boulder, Department of Civil, Environmental, and Architectural Engineering, Boulder, CO 80303, USA 3 Perm National Research Polytechnic University, Faculty of Chemical Technologies, Industrial Ecology and Biotechnology, Perm 614990, Russia 4 University of Colorado Boulder, Environmental Engineering Program, Boulder, CO 80303, USA 5 Huma Inc, Gilbert AZ 85233, USA Commercial products marketed as fulvic acids are increasingly derived from non-humic materials, creating a need for a rapid and practical method to distinguish authentic fulvic fractions from adulterated products. In this study, a UV spectrophotometric screening approach was developed using ten indices that capture characteristic features of the spectra of hydrophobic fulvic acids. Fulvic fractions were diluted to 5 ppm carbon, UV spectra were collected, normalized, and used to calculate ten spectral indices. For each sample, index values were compared with those of IHSS Suwannee River fulvic acid and IHSS Pahokee Peat fulvic acid reference standards, and an equally weighted average percent error was calculated. A 70% cutoff for this average percent error was applied as a screening threshold to classify samples as fulvic or non-fulvic. Fifty-four test samples were evaluated, including commercial products, known fulvic fractions, and non-humified materials. Fourteen of twenty-five commercial products were identified as containing fulvic fractions, while all known fulvic isolates and non-humified test samples were correctly differentiated. Within the ranges tested, neither increased metal ion concentration nor variation in total organic carbon concentration from 1 to 10 ppm affected classification performance.[1] The method was further tested against fulvic fractions containing various common agricultural micronutrients and fertilizers in currently unpublished data. The method investigated could be a suitable screening tool for most commercial products and is capable of accurately distinguishing products that contain fulvic fractions. The method accurately found all 11 fulvic fractions isolated from known humic substances as fulvic, and all 11 test samples prepared from non-humified materials as non-fulvic.
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