The strontium isotope effect in the chemical exchange reaction of chromatography using a cryptand (213, 2, 2) polymer as a solid phase was investigated. Isotope enrichment factors were decreased with DMSO contents in water. The enrichment factor epsilon(84,88) for Sr-84 in comparison to Sr-88 in pure water system was epsilon(84,88) = (6.33 +/- 0.48) x 10(-3) and that in 100% DMSO system was epsilon(84,88) = (10.14 +/- 1.08) x 10(-3). In almost all systems except for 50 v% DMSO-water system, the enrichment factors were not scaled with Deltam/mm', where Deltam is the mass difference for the isotopes m and m'. In these systems, the difference of nuclear size and shape, namely the field shift was found to dominate the isotope effects of strontium. In the water system, the contribution of the nuclear size and shape was 7.47 x 10(-3), and that in the DMSO was -17.97 x 10(-3). Those values were larger than the contribution of the mass effect.