The effect of counter anion in isotope exchange reaction of strontium was investigated by liquid chromatography using a cryptand (2B, 2, 2) polymer as a stationary phase. Isotope enrichment factors were assumed to be in the order: Perchlorate > chloride > nitrate > bromide. The maximum isotope enrichment factor of Sr-84 was (13.2 +/- 2.2) x 10(-3) and the minimum was (4.2 +/- 1.2) x 10(-3). No isotope enrichment factor showed a linear relation to the difference of atomic masses. The contribution of the field shift in atomic electrons was greater to the isotope enrichment factor than the vibrational frequency shift between an isotope and a ligand. Chloride as a counter anion to strontium was the largest isotope enrichment factor.