Dimethylsulfoxide augmented calcium isotope effect with polymer-bound 18-crown-6 in a chromatographic chemical exchange system
- EG & G Mound Applied Technologies, Miamisburg, OH (United States)
The enrichment of calcium isotopes with polymer-bound 18-crown-6 proceeds according to the following chemical exchange reaction: {sup 40}Ca{sup 2+}{sub (fluid)} + {sup 44}CaL{sup 2+}{sub (solid)} {leftharpoondown}{rightharpoonup} {sup 44}Ca{sup 2+}{sub (fluid)} + {sup 40}CaL{sup 2+}{sub (solid)} where L{sub (solid)} represents 18-crown-6 bound to a polystyrene solid support. The separation coefficient, {epsilon}, for this exchange was found to be larger when dimethylsulfoxide (DMSO) was added to the fluid phase. When a fluid phase of 70% methanol and 30% chloroform (volume) is used as stock solution, {epsilon} = 0.0035 {plus_minus} 0.0003 (for the {sup 40}Ca-{sup 44}Ca isotope pair) after DMSO is added. DMSO was added to the extent of two and five volume percent. This compared to {epsilon} = 0.0025 {plus_minus} 0.0002 without DMSO. The difference in the isotope effect is attributed to a change in the coordination sphere of the calcium solvate in the fluid phase. The stability of the calcium-crown complex was reduced when DMSO was added. The binding constant of the calcium-crown complexation-decomplexation reaction was smallest when the higher concentration of DMSO was used. This was attributed to the formation of a calcium complex with DMSO in the fluid phase.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-88DP43495
- OSTI ID:
- 145146
- Report Number(s):
- CONF-911049--
- Journal Information:
- Separation Science and Technology, Journal Name: Separation Science and Technology Journal Issue: 1-3 Vol. 28; ISSN 0149-6395; ISSN SSTEDS
- Country of Publication:
- United States
- Language:
- English
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