The Determination of 226 Ra in Water Samples Anil H. Thakkar Eichrom Technologies, Inc. eichrom...

The Determination of 226Ra in Water Samples

Anil H. Thakkar

Eichrom Technologies, Inc.

eichromTECHNOLOGIES INC

Objective

• To design a procedure for radium in water samples using Eichrom’s cation exchange resin and Ln Resin.


Current Procedure Used

• Barium sulfate precipitation

• Conversion to BaCO3- tedious and time consuming



• Sample + Ba carrier + Ba-133 + Conc.H2SO4_+ Heat BaSO4

• Precipitate allowed to settle for several hours or overnight

• Precipitate collected and converted to BaCO3

Current Procedure Used

New Approach

Water samples

Cation exchange resin column

Eichrom Ln Resin column


Preparation of Water Samples

• 0.5 L / 1.0 L water samples, acidified to

pH 2

• Add 133Ba as a tracer


Eichrom Cation Exchange Column

• Load solution: 0.5 L/ 1.0 L of sample

• Rinse with 50 mL of 0.1M HNO3

• Strip Ra and Ba with 50 mL of 8M HNO3


Preparation of Load Solution for Ln Resin Column

• Evaporate eluent from cation exchange column to dryness

• Dissolve residue in 10 ml of 0.095M HNO3 acid

• Load on Eichrom Ln Resin column


Ln Resin Column Separation

(1) Load: 10 mL of mL 0.095M HNO3,

(3) Strip: 10 mL of 0.35M HNO3

Collect 1) and (2) for Ba & 226Ra

collect (3) for 228Ac

(2) Rinse: 15 mL of 0.095M HNO3


226Ra Via Alpha Spectrometry• Evaporate 226Ra/133Ba fraction to 10 mL volume

• Add 3 mL of 40% sodium sulfate, 4 drops of 1:1 acetic acid. Swirl

• Add 0.2 mL of seeding suspension. Mix

• Place tubes in cold water bath for 30 minutes

• Filter on 0.1 micron filters, count via alpha spectrometry


133Ba Via Gamma Counter

• Count 133Ba tracer yield via gamma spectrometry


228Ac Via Gas-Flow Proportional Counter

• Add 50 micrograms of cerium carrier

• Add 1.0 mL of HF

• Filter on 0.1 micron filters

• Measure for beta radiation


226Ra % Recoveries-0.5L DI Water

0102030405060708090

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Sample #


226Ra Alpha Spectrum


133Ba Gamma SpectrumTECHNOLOGIES INCeichrom

226Ra, 224Ra, and Daughters


226 Ra222Rn

224Ra

218Po220Rn

226Ra % Recoveries in Tap water

0

20

40

60

80

100

120

1 2 3 4 5

Sample #

4 Tap Water (0.5L)5 Tap Water (1.0 L)


226Ra in EPA SampleSept.18, 1998

Sample # Ba-133% Yield

EichrompCi/L

1 89 1.562 100 1.233 98 1.45

Average 95.7 + 6 1.41 + 0.17

ExpectedEPA Value

1.7 + 0.5pCi/L


Summary

• Cation exchange resin option: – provides a good replacement for the time

consuming BaSO4 precipitation steps

– it eliminates inconsistent metathesis steps– reduces usage of chemicals/reagents– provides consistency and saves time

• Acceptable 226Ra recoveries


The Determination of 226 Ra in Water Samples Anil H. Thakkar Eichrom Technologies, Inc. eichrom...

Documents

Transcript of The Determination of 226 Ra in Water Samples Anil H. Thakkar Eichrom Technologies, Inc. eichrom...