Characterization of humic substances by means of high-performance size exclusion chromatography

High-performance size exclusion chromatography is a simple and rapid method for characterization of macromolecules like humic substances according to their molecular size distribution. Secondary chromatographic effects like ionic and hydrophobic interactions can be overcome by the choice of suitable mobile phases. One silica-based and two polymer-based columns were used and their requirements for mobile phase conditions 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 with the polymer-based columns minimized the unwanted interactions between samples and support materials. Polystyrene sulfonates of known molecular weight can be used to construct calibration curves for molecular weights of humic substances.