AN-1401

Rapid Determination of 226Ra inEmergency Urine and Water

Summary of Method 226Ra is isolated from 100mL urine samples or up to 1 liter water samples and measured byalpha spectrometry as described by Maxwell, et al.1 Radium is precipitated from samples with calcium phosphate. The
calcium phosphate precipitate is dissolved in hydrochloric acid, and cation exchange chromatography is used to purify
radium and barium from matrix ions. Eichrom DGA Resin is used to remove other alpha emitting nuclides from radium.
Samples are prepared for radium measurement by alpha spectrometry via barium sulfate microprecipitation onto
Eichrom Resolve® Filters. Sample preparation, including alpha spectrometry source preparation, for batches of 12
samples can be completed by a single operator in as little as 3-4 hours, with >90% yield of Radium. Yields can betraced with 133Ba by gamma spectrometry or 225Ra(229Th) by alpha spectrometry. If tracing with 225Ra, at least 8 hours ofingrowth time are required for the alpha emitting 217At daughter of 225Ra prior to alpha spectrometry measurements.
Reagents
Cation Exchange Resin (Eichrom C8-B500-F-H)
DGA Resin, Normal 2mL Cartridges (Eichrom DN-R50-S)
Ammonium Hydroxide (Listed as 28% NH3 or 56% NH4OH)
Nitric Acid (70%)
Hydrochloric Acid (37%)
Deionized Water
Hydrogen Peroxide (30%)
133Ba or 225Ra(229Th) Tracer*
1.25M Ca(NO3)2*133Ba allows immediate counting.
3.2M (NH4)2HPO4225Ra(229Th) requires >8hrs
Barium Carrier (1mg/mL)
ingrowth before alpha meas.
Isopropyl Alcohol
Ba/Ra
recoveries can differ by up
Ammonium Sulfate
to 10% in difficult matrices.
Denatured Ethanol

Figure 1. Sample Preparation
100 mL urine or 1L waterAdjust to pH2 with HNO3+Tracer 133Ba or 225Ra (229Th)+1 mL 1.25M Ca(NO3)3+5mL 3.2 M (NH4)2HPO4****A calcium phosphate ppt. was chosen to minimize
reagent background. A CaCO3 ppt (AN1413) canbe used for higher activity samples or where
reagent blank is less important.

Equipment
Plastic Chromatography Column (Eichrom AC-50E-5M)
Column Extension Funnel (Eichrom AC-20X-20M)
Vacuum Box (Eichrom AR-24-BOX or AR-12-BOX)
Cartridge Reservoir, 20mL (Eichrom AR-200-RV20)
Inner Support Tubes-PE (Eichrom AR-1000-TUBE-PE)
Yellow Outer Tips (Eichrom AR-1000-OT)
Resolve Filter in Disposable Funnel (Eichrom RF-DF-25-25PP01)
50mL and 250mL Centrifuge Tubes
Centrifuge
Hotplate
150mL Glass beakers
Vacuum Pump
Heat Lamp
Stainless Steel Planchets with adhesive tape
Alpha Spectrometry System
Gamma Spectrometry System (if 133Ba tracer used)

Adjust to pH 10 with NH4OH

Mix Well
Wait 5-10 min

Centrifuge 3500 rpm, 10 min
Dissolve Precipitate in
10mL 1.5M HCl
Add 7mL 1.5 HCl

Proceed to Column Purification

DecantSupernate
To WasteFigure 2. Column Purification and Alpha Source Preparation(8) Add 50ug Ba carrier. Mix well.

(1) Prewash 5.0g 50Wx8
200-400 mesh, cationexchange resin column1:-10mL deionized water-20mL 6M HCl-10mL 0.5M HCl(9) Add 3g (NH4)2SO4 and 5mL isopropanol. Mix well.
(10) Place in ice bath for 30 minutes.

(2) Load Sample2(11) Set up Resolve® Filter Funnel
on vacuum box.

(3) Rinse 30mL 3M HCl(4) Add 2mL DGA cartridge below
cation exchange column.

(12) Wet filter with 3mL 80% ethanol
followed by 3mL DI water.

(5) Strip Ra/Ba with 25mL 5M HNO3.
(6) Add 2mL 30% H2O2.
Evaporate to dryness.
(7) Dissolve residue in
10mL 1.5M HCl.

226(18) Remove filter from funnel
assembly and mount filter on
stainless steel planchet withadhesive tape.

(13) Filter sample.
(14) Rinse sample
tube with 5mL
DI water andadd to filter.

(19) Dry filter under heat lamp for
3-5 minutes.
(20) Measure 226Ra and 225Ra(217At)
by alpha spectrometry after >8hours 217At ingrowth. (133Ba bygamma, if necessary.)(15) Rinse filter funnel
with 3mL DI water.
(16) Rinse filter funnel
with 1-2mL 100%ethanol.

Ra(17) Draw vacuum until filter is dry.
1If using 133Ba tracer, 3.0g of cation exchange resin and proportionally smaller rinse volumes may be used.
2If tracing with 229Th, a 20mL 1M HCl-1M H3PO4 rinse following the sample load can improve purity of final 226Ra fraction.

Table 1.

226

Ra Analysis Results from 100mL Spiked Urine Samples
226

TracerRa Measured Value133

Ba % Recovery
Replicates AverageSD

226(mBq/sample)
Ra ReferenceValue (mBq/sample) AverageSD% Bias

693+

373.7

76.5+4.73.9698+

318.4

17.9+0.8-2.7

692+

5Blank*0.15+0.12*Calculated MDA 15 mBq/L (4 hr count, 100 mL sample)*Calculated MDA 5 mBq/L (16 hr count, 100 mL sample)

References
1) Sherrod L. Maxwell, Brian K. Culligan, Jay B. Hutchinson, Robin C. Utsey and Daniel R. McAlister, “RapidDetermination of 226Ra in Emergency Urine Samples,” J. Radioanal. Nucl. Chem., 300(3), 1159-1166 (2014).
1955 University Lane Lisle, IL 60532, USA+1 (630)963-0320

www.eichrom.com