Experimental determination of chlorine isotope separation factor by anion-exchange chromatography

Chlorine isotope fractionation factor was determined by strongly basic anion-exchange chromatography with 0.1 mol/l HCl at 25 °C. The magnitude of the factor was calculated as a single-stage separation factor of 1.00030 with analytical precision of 0.00006 (1(sigma)). The results showed that the lighter isotope (35Cl) was preferentially fractionated into the resin phase, while the heavier one (37Cl) enriched into the aqueous phase. This trend suggested that the hydrated Cl- ions in the aqueous phase were slightly more stable than the hydrated Cl- ions electrostatically interacting with the ion-exchange groups of the resin.