At. Kuiters et W. Mulder, COMPLEXOMETRIC GEL-PERMEATION CHROMATOGRAPHY OF SOLUBLE HUMIC SUBSTANCES USING SEPHADEX G-25, Journal of soil science, 44(3), 1993, pp. 501-512
Sephadex G-25 was used with 0.01 m sodium acetate containing a concent
ration of 3 x 10(-5) M Cu(II) as eluent to establish the molecular-siz
e distribution (MSD) and the Cu-complexation of molecular-weight fract
ions of organic solutes. The appropriateness of this modified gel perm
eation method for complexometric measurements on soluble humic substan
ces was investigated employing various types of soil solutions. The pr
esence of Cu in the eluent had an effect on the MSD obtained by elimin
ation of electrostatic repulsion between gel and solutes. No evidence
was found that the presence of Cu in the chromatographic system induce
d aggregation of the organic substances. The Cu-binding capacity of th
e samples as obtained with this gel permeation method was found to inc
rease linearly over a wide sample concentration range varying from 40-
2000 mg Cd m-3. No interference was observed between the Cu-complexati
on by exclusion and inclusion peaks in the chromatograms. The analyses
revealed that the fraction apparently low in molecular weight makes a
large contribution to the complexation potential of forest soil solut
ions.