CHARACTERIZATION OF HUMIC SUBSTANCES BY MEANS OF HIGH-PERFORMANCE SIZE-EXCLUSION CHROMATOGRAPHY

High-performance size exclusion chromatography is a simple and rapid m ethod for characterization of macromolecules like humic substances acc ording to their molecular size distribution. Secondary chromatographic effects like ionic and hydrophobic interactions can be overcome by th e choice of suitable mobile phases. One silica-based and two polymer-b ased columns were used and their requirements for mobile phase conditi ons were tested. Using a 0.02 mol L(-1) phosphate buffer, pH 6.5, with the silica-based column, and a 0.02 mol L(-1) neutral salt solution w ith the polymer-based columns minimized the unwanted interactions betw een samples and support materials. Polystyrene sulfonates of known mol ecular weight can be used to construct calibration curves for molecula r weights of humic substances.