Isotope preparation method
The present invention provides a method for the generation of 223 Ra of pharmaceutically tolerable purity comprising i) preparing a generator mixture comprising 227 Ac, 227 Th and 223 Ra; ii) loading said generator mixture onto a strong base anion exchange resin; iii) eluting said 223 Ra from said strong base anion exchange resin using a first mineral acid in an alcoholic aqueous solution to give a first eluted 223 Ra solution; iv) loading the 223 Ra of the first eluted 223 Ra solution onto a strong acid cation exchange resin; and v) eluting the 223 Ra from said strong acid cation exchange resin using a second mineral acid in aqueous solution to provide a second eluted solution. The invention additionally provides products of corresponding purity and/or products obtained or obtainable by such a method.
1. A method for the generation of 223 Ra of pharmaceutically tolerable purity comprising
i) preparing a generator mixture comprising 227 Ac, 227 Th and 223 Ra;
ii) loading said generator mixture onto a strong base anion exchange resin;
iii) eluting said 223 Ra from said strong base anion exchange resin using a first mineral acid in an alcoholic aqueous solution to give a first eluted 223 Ra solution;
iv) loading the 223 Ra of the first eluted 223 Ra solution onto a strong acid cation exchange resin; and
v) eluting the 223 Ra from said strong acid cation exchange resin using a second mineral acid in aqueous solution to provide a second eluted solution, wherein said 223 Ra of pharmaceutically tolerable purity comprises less than 45Bq 227 Ac per MBq 223 Ra.
2. The method of claim 1 additionally comprising the step of:
x) eluting said 227 Ac and 227 Th from said strong base anion exchange resin using a third mineral acid in aqueous solution, whereby to provide a mixture of 227 Ac and 227 Th, wherein step occurs at any time following step ii).
3. The method as claimed in claim 2 wherein at least 99.9% of the 227 Ac loaded onto the resin in step ii) is recovered in step x).
4. The method as claimed in claim 3 wherein at least 98% of the 227 Th loaded onto the resin in step ii) is recovered in step x).
5. The method of claim 1 additionally comprising the step of:
y) storing said mixture of 227 Ac and 227 Th for a period sufficient to allow ingrowth of 223 Ra by radioactive decay, whereby to regenerate a generator mixture comprising 227 Ac, 227 Th and 223 Ra.
6. The method of claim 1 wherein the method purifies sufficient 223 Ra for more than 10 typical doses.
7. The method of claim 1 wherein a 227 Ac radioactivity of at least 500 MBq is employed in step i).
8. The method of claim 1 wherein the strong base anion exchange resin is a polystyrene/divinyl benzene copolymer based resin.
9. The method of claim 8 wherein said polystyrene/divinyl benzene copolymer based resin contains 1-95% DVB.
10. The method of claim 1 wherein the strong base anion exchange resin is an R—N + Me 3 type (type I) resin or an R—N + Me 2 CH 2 CH 2 OH (Type II) resin.
11. The method of claim 1 wherein the first mineral acid is an acid selected from the group consisting of H 2 SO 4 and HNO.
12. The method of claim 11 wherein the first mineral acid is HNO 3 .
13. The method of claim 1 wherein the first mineral acid is used at a concentration of 0.01 to 5 M.
14. The method of claim 1 wherein the alcoholic aqueous solution comprises at least one alcohol selected from the group consisting of methanol, ethanol, and isopropanol.
15. The method of claim 14 wherein the alcoholic aqueous solution comprises methanol.
16. The method of claim 1 wherein the alcoholic aqueous solution comprises 20 to 99% methanol.
17. The method of claim 1 wherein the first eluted 223 Ra solution has a contamination level of no more than 100 Bq 227 Ac per 1 MBq 223 Ra.
18. The method of claim 1 wherein the steps of loading the generator mixture onto the base anion exchange resin and eluting the first eluted 223 Ra solution provide a separation ratio of 223 Ra to 227 AC of at least 10,000:1.
19. The method of claim 1 wherein the strong acid cation exchange resin is a polystyrene/divinyl benzene copolymer based resin.
20. The method of claim 19 wherein said polystyrene/divinyl benzene copolymer based resin contains 1-95% DVB.
21. The method of claim 1 wherein the strong acid cation exchange resin is of SO 3 H type.
22. The method of claim 1 wherein the second mineral acid is an acid selected from the group consisting of H 2 SO 4 , HNO 3 , and HCl.
23. The method of claim 22 wherein the second mineral acid is HNO 3 .
24. The method claim 1 wherein the second mineral acid is used at a concentration of 0.5 to 5 M.
25. The method of claim 1 wherein the aqueous solution does not comprise any significant amount of an alcohol selected from the group consisting of methanol, ethanol, and isopropanol.
26. The method of claim 25 wherein the aqueous solution is substantially free of methanol.
27. The method of claim 1 wherein the second eluted solution has a contamination level of no more than 45 Bq 227 Ac per 1 MBq 223 Ra.