IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 BOOK OF ABSTRACTS 258 Poster Session / Technologies and Applications Hall A coefficients of variation were 40.3%, 6.45%, 37.3% and 8.94%. The results indicate particularly robust performance for humic-acidrich matrices and identify fulvic acid determination as the more sensitive analytical fraction, especially at lower concentrations. By distinguishing between free and extractable humic and fulvic acid fractions, MSZ 1129:2026 provides a practical and standardizable framework for comparing humic materials, supporting industrial quality control, product specification and harmonized regulatory and scientific evaluation of humic substances. References 1. MSZ 1129:2026, Csicsor method for the determination of humic substances. Determination of the humic acid and fulvic acid content of the natural humus deposits and artificial growing media, Hungarian Standards Institution, Budapest, 2026. 2. ISO 5073:2013, Brown coals and lignites - Determination of humic acids, International Organization for Standardization, Geneva, 2013. 3. ISO 19822:2018, Fertilizers and soil conditioners - Determination of humic and hydrophobic fulvic acids concentrations in fertilizer materials, International Organization for Standardization, Geneva, 2018. Keywords: humic substances; humic acid; fulvic acid; Csicsor method; MSZ 1129:2026; gravimetric determination; standardization; alkaline extraction; leonardite.
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