225Ac/225Ra Generator
AN-1614-10
Summary of Method A method for the preparation of 225Ac (t1/2 = 10 days) and 225Ra (t1/2 = 14.8 days) from 229Th(t1/2 = 7340 years) source material is presented. The method employs 2mL cartridges of UTEVA and DGA resins toobtain high purity 225Ac in small volumes of eluate while preserving valuable 229Th source material. The method is meantfor 225Ac tracer production from 229Th containing 5-10mg or less of total Th. For separations from larger masses of Th
see the Eichrom website bibliography for other options (Recent Advances in the Recovery and Purification of Actinium
Isotopes, Horwitz and McAlister, National Meeting of the American Chemical Society, 2009). The source material,
containing 229Th, 225Ac, 225Ra and other daughter nuclides in 4M HNO3, is loaded onto stacked 2mL cartridges of UTEVA
and DGA resins. 229Th is retained on UTEVA, while 225Ac is retained on DGA and 225Ra passes through both cartridges.
225Ra can be saved for use as a radiotracer or as an additional source of 225Ac, following a suitable ingrowth period.
225Ac is recovered from DGA with a small volume of 0.1-2.0M HCl. The 229Th source is recovered from UTEVA with asmall volume of 0.5M HCl. Following a suitable ingrowth period, the 229Th can be acidified to 4M HNO3 and used toproduce additional 225Ac and 225Ra. The 229Th is preserved nearly indefinitely and continuously purified from chemical
and radiologic impurities run to run.
Equipment
Glass vials for storage of 229Th source.
Glass or plastic vials/bottles for collection of 225Ac. 225Raand waste.
5, 10 or 20mL plastic luer lock syringes
Gamma spectrometry system and/or alpha spectrometry
for measurement of 225Ac(221Fr), 225Ra and 229Th.

Reagents
UTEVA Resin Cartridges (Eichrom UT-R50-S)
DGA Resin Cartridges (Eichrom DN-R50-S)
229Th Source
Deionized Water
HCl
HNO3

Ingrowth of
100

229

225

Ac and225

Ra from

229

Ingrowth ofTh

Ac from

225

Ra

100
Th
225

80
225

60% Activity

80% Activity

225

Ra
225

Ac

40Ra

60
225

40

Ac

2020000102030

Days

40

50

6003

6

912Days151821

225

Ac/225Ra/229Th Separation(6) Rinse DGA with 10mL 8M HCl.

(1) Precondition stacked 2mL
cartridges of UTEVA andDGA with 10mL 4M HNO3.

(7) Strip 225Ac with 10mL
0.1M HCl. (For higher229Th decontamination,use 10mL of 2M HCl.)(2) Acidify 229Th eluate fromprevious separation with5mL HNO3. (If new 229Th
source, dilute to 20mL with
4M HNO3.)(3) Load 229Th and daughtersin 20mL 4M HNO3. Collectand save eluate containing 225Ra.*(4) Rinse UTEVA/DGA with 10mL
4M HNO3. Collect 225Ra.*(8) Strip 229Th from UTEVA
cartridge with 15mL 0.5M
HCl. (More completerecovery may be obtainedby stripping in opposite
direction of load.) Save229Th for future use.

(5) Separate UTEVA and DGAcartridges.
*225Ra can used directly as a tracer or as a source of additional 225Ra.

UTEVA Resin

310DGA

610k' Ac, Ra <1for all [Acid], M

510210Th-HNO3

410

Th-HNO3

Ac-HNO33101k' 10k'

210Th-HCl

Th-HCl110010010-110k' Ra <1 forall [Acid]

Ac-HCl

-1-1

10010

110[Acid], M

10-101011010[Acid], M

References
1) McAlister and Horwitz, “Chromatographic Generator Systems for the actinides and natural decay series elements,”
Radiochimica Acta, 99:1-9 (2011).
1955 University Lane Lisle, IL 60532, USA+1 (630)963-0320

www.eichrom.com