DETERMINATION OF MOLECULAR-SIZE DISTRIBUTIONS OF HUMIC ACIDS BY HIGH-PERFORMANCE SIZE-EXCLUSION CHROMATOGRAPHY

High-performance size-exclusion chromatography (HPSEC) was applied to the study of humic acids and a method for the rapid determination of reliable molecular size distributions of these substances was developed. Using commercial HPSEC columns, in conjunction with a neutral saline solution as eluent, molecular size distributions of four samples of humic acids of various origin and nominal average molecular weights were obtained. Measurements were independent of the operating conditions and based on differences in the molecular sizes of the humic acids examined.