Sephadex‐Gelfiltration von Huminsäuren und deren Gehalt an Aminosäuren

Abstract

Gel filtration on Sephadex of humic acids and their content of amino acids Brown humic substances from the Ah of an iron‐humus podzol were separated on Sephadex G 25 into three fractions. The first fraction (Ve/Vo = 1.0–1.5) has the lowest value of Q 4/6 (5.0–8.0), the second the highest Q 4/6 (10.0–12.0) and the third a middle one (8.0–10.5). The adsorption effect may take place during separation. The asymmetric form of the integral elution curves of the first fraction indicated that the humic substances are a set of particles with different size. The separation is influenced by diffusion into the pores of gel matrix. In the first fraction were determined 16, in the second 13 and in the third 10 amino acids. The titration curves of the first fraction (after separation on G 25) indicated that the rate of pH change with alkali added becomes its maximum at pH 6.5–7.5 at different ionic strengths. Dialysed humic acids (H+ form) were fractionated on G 75. The alkali consumption up to pH 7.5 in the eluate shows that small amounts of mineral acids increase the conductivity of the solution. Their Ve is lower than that of the second fraction of humic acids. Therefore it is impossible to determine the alkali consumption by the second fraction and by the humic acids as a whole without their total desalting.