The high-performance size-exclusion chromatography (HPSEC) and radiochromatography (HPSERC) was used for the identification
of radiocesium and radiostrontium interaction with humic acid. It was found that the behavior of humic acid on size-exclusion
chromatography is sensitive to the salt concentration and pH of the mobile phase. At lower ionic strength and in acidic region
of pH, the Aldrich humic acid exhibited three main fraction within the ranges >760 kDa, 25–100 kDa and <5 kDa. Radiocesium
was found in the low-molecular fractions (<1 kDa) of humic acids but radiostrontium interacts preferably with the fractions
of humic acid of molecular weight within the range 2–5 kDa.