Humic substances as a background electrolyte in capillary electrophoresis

摘要

Humic substances (HS) as a background electrolyte in capillary electrophoresis afford the possibility to characterise HS/reagent interactions. Thus, added Pb(NO3)2 reveals specific characteristic regions in electropherograms that correlate with the salt concentration. These regions form because of the on-capillary complexation of Pb~(2+) with HS: fulvic acid, hymatomelanic acid and humic acid. The formation of two complexes (Pb/HS fractions 1 and II), which have different mobility, was observed. Each of the HS fractions contains those complexes in a different ratio. Differences in the electropherograms apparently reflect structural differences in the fractions. The peak areas of both complexes have a good linear correlation with the concentration of injected Pb~(2+).