EPA-600/4-76-011
March 1976
Environmental Monitoring Series
MEASUREMENT OF STRONTIUM-89 AND
STRONTIUM-90 IN ENVIRONMENTAL WATERS
A Tentative Reference Method
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL MONITORING series.
This series describes research conducted to develop new or improved methods
and instrumentation for the identification and quantification of environmental
pollutants at the lowest conceivably significant concentrations. It also includes
studies to determine the ambient concentrations of pollutants in the environment
and/or the variance of pollutants as a function of time or meteorological factors.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/4-76-011
March 1976
MEASUREMENT OF STRONTIUM-89 AND STRONTIUM-90 IN ENVIRONMENTAL WATERS
A Tentative Reference Method
by
Quality Assurance Branch
Monitoring Systems Research and Development Division
Environmental Monitoring and Support Laboratory
Las Vegas, Nevada 89114
ROAP Number 22ACW
Program Element 1HA327
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
LAS VEGAS, NEVADA 89114
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DISCLAIMER
This report has been reviewed by the Environmental Monitoring and Support
Laboratory-Las Vegas, U.S. Environmental Protection Agency, and approved for
publication. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
Effective June 29, 1975, the National Environmental Research Center-Las
Vegas (NERC-LV) was designated the Environmental Monitoring and Support Labo-
ratory-Las Vegas (EMSL-LV). This Laboratory is one of three Environmental
Monitoring and Support Laboratories of the Office of Monitoring and Technical
Support in the U.S. Environmental Protection Agency's Office of Research and
Development.
ii
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CONTENTS
Page
1. Principle and Applicability 1
2. Range and Sensitivity 2
3. Interferences 2
4. Precision and Accuracy 3
5. Apparatus 3
6. Reagents 4
7. Procedures 7
8. Calibration 13
9. Calculations and Reporting 13
APPENDIX A. Error and Statistical Calculations 16
APPENDIX B. Yttrium-90 Decay and Ingrowth Factors
(0-72 Hours) 18
APPENDIX C. Yttrium-90 Ingrowth Factors (0-27 Days) 19
APPENDIX D. Strontium-89 Decay Factors (0-59.5 Days)
= 51 Days) 20
iii
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TENTATIVE REFERENCE METHOD FOR THE MEASUREMENT OF
STRONTIUM-89 AND STRONTIUM-90 IN ENVIRONMENTAL WATERS
1. Principle and Applicability
A known amount of inactive strontium ions, in the form of strontium
nitrate, is added to the sample as a "carrier" to determine percent of
recovery. The strontium, both carrier and radionuclide, is separated
from other radioactive elements and sample solids by precipitation as
strontium nitrate from fuming nitric acid solution. The strontium
carrier and radionuclides are then precipitated as strontium carbonate,
dried, weighed to determine recovery of carrier, and the radioactivity
determined. The radioactivity counted is normalized to 100 percent
recovery by using the recovery factor.
It is impossible to separate the isotopes strontium-89 and
strontium-90 by chemical procedure; therefore, the amount of strontium-
90 is determined by separating and counting the activity of its daugh-
ter, yttrium-90. At equilibrium, the activity of yttrium-90 and
strontium-90 are equal. The strontium-89 is then determined by
difference.
This method is applicable to measuring radioactive strontium-89
and 90 or only strontium-90 in drinking water or in filtered raw water.
It is also applicable to sewage and industrial wastes, provided steps
are taken to destroy organic matter and eliminate other interfering
ions.
-------
2. Range and Sensitivity
L
The minimum limit of concentration to which this method is appli-
cable will depend on sample size, counting efficiency, background, and
counting time. Since radioactivity decay is random rather than uniform
in nature, it is necessary to count the decay emissions (in this case,
beta particles) sufficiently long to obtain the desired statistical re-
liability. It is recommended that samples be counted long enough so
that samples with strontium-89 and/or strontium-90 activities as low as
the detection limit of the method and the counting instrument used will
have a counting error no greater than the sample net count rate (when
counting error counts per minute (cpm) equals sample net cpm, the count-
ing error is 100 percent). For instance, when a 1-liter water sample
is analyzed for strontium-90 by this method and is counted for 20 min-
utes in a low background beta counting system (2 cpm background), with
a counting efficiency of 41 percent, and a gross count rate of 3 cpm is
obtained, the sample will have a net count rate of 1 cpm and a counting
error of plus or minus (±) 1 cpm at the 95 percent confidence level.
This corresponds to a detection limit of 1 ± 1 pCi/liter. Samples
having higher concentrations and counted for the same time (20 minutes)
will have correspondingly lower counting errors.
The range of the method is 1 pCi/liter to 10" pCi/liter for 1-liter
sample size. Smaller aliquots should be analyzed for strontium-89 and
90 activities above 10** pCi to avoid counting instrument resolution
losses.
3. Interferences
Radioactive barium will precipitate with radioactive strontium.
Stable barium is added to the sample and then steps are included in the
method that separates barium from strontium. Radium isotopes are also
removed with the barium.
-------
Samples that naturally contain significant amounts of stable stron-
tium will cause errors in the recovery of the added strontium carrier.
Blank samples to which no strontium carrier is added should be run to
determine natural strontium content. Hard waters contain calcium which
precipitates with the strontium in the initial carbonate precipitation.
If not separated, the calcium will cause errors in the recovery of the
strontium carrier. This method includes steps to remove calcium from
the sample.
4. Precision and Accuracy
Water samples containing 10, 100, and 1000 pCi/liter of both
strontium-89 and 90 can be analyzed for each radioisotope with a pre-
cision of less than ± 25 percent, ± 15 percent, and ± 10 percent re-
spectively at the 95 percent confidence level. The overall accuracy
is a combination of the accuracy of the standard used and the precision
and accuracy of the measurement procedure. Using this method, analysis
of water samples containing as little as 10 pCi each of strontium-89
and 90 should be accurate within ± 25 percent at the 95 percent confi-
dence level. The method is slightly biased on the low side.
5. Apparatus
Low background beta counting system (A thin-window
proportional or Geiger-MUller counter, 2-inch diameter
or more window, with not more than 3 cpm background on
the beta voltage plateau, is recommended.)
Stainless steel planchets, 2-inch diameter by 1/4-inch
deep
47-mm diameter glass fiber and 0.45-micrometer pore
membrane filters (cellulose triacetate type)
Filter holder, 2-liter filter flask, and stopper adapter
-------
Centrifuge and 50-mi Hi liter (ml) centrifuge tubes
•4
Separatory funnels, 60-ml
Drying oven
Desiccator and desiccant
Sintered-glass (fine) crucibles
Beakers: 250-ml, 400-ml, 2000-ml
Graduated cylinders: 50-ml, 100-ml, 1000-ml, 4000-ml
Hot water bath
6. Reagents. All chemicals should be of "reagent-grade" or equivalent
whenever they are commercially available.*
Strontium carrier (10 mg/ml): Dissolve and dilute
24.16 grams (g) of Sr(N03)2 to 1 liter in a volu-
metric flask with distilled water. Thoroughly mix
and standardize as follows: Carefully pipet three
10.0-ml portions of the carrier solution into sepa-
rate 50-ml centrifuge tubes. Add 15 ml of 2N NaaCOs
solution (see sodium carbonate solution below) and
stir. Heat in a boiling water bath for 15 to 20
minutes. Allow to cool and filter out the SrCOs pre-
cipitate in a tared sintered-glass (fine) crucible.
Wash the precipitate and the crucible walls with
three 5-ml distilled water portions adjusted to pH 8
* "Reagent Chemicals, American Chemical Society Specifications,"
American Chemical Society (ACS), Washington, DC. For reagents not
listed by the ACS see "Reagent Chemicals and Standards" by Joseph Rosin,
D. Van Nostrand Company, Inc., New York, NY, or the "United States
Pharmacopeia" for purity tests.
-------
with NHi,OH, and with three 5-ml portions of acetone.
Dry the crucible for 30 minutes in a 100° C oven.
Cool the crucibles in a desiccator and weigh.
Calculations:
.. . .. mg of SrCOa x 0.5935
Strontium, mg/ml = — nnfiT
Yttrium carrier (10 mg/ml): Dissolve and dilute
43 g of Y(N03)3*6H20 plus 5 ml of concentrated nitric
acid to 1 liter in a volumetric flask with distilled
water. Standardize the carrier solutions by the
following procedure: Carefully pipet three 10.0-ml
portions of the carrier solution to separate 50-ml
centrifuge tubes. Add 40 ml of saturated ammonium
oxalate solution to each centrifuge tube and stir.
Heat in a hot water bath (near boiling) for 30
minutes. Cool in an ice bath. Filter the precipi-
tates into a tared sintered-glass (fine) crucible.
Wash the crucible walls and the precipitate with
three 5-ml portions of distilled water, then with
three 5-ml portions of ethyl alcohol, and finally
with three 5-ml portions of acetone. Air dry the
crucibles for 1 hour or longer and weigh.
Calculations:
Y/Y2(C2003-9H20 = 88.92/604.05 = 0.1472
V4-4. . , , mg of Y2(C2003'9H20 x 0.1472
Yttrium, mg/ml = — - j^^
Barium carrier: Dissolve and dilute 19.0 g of
Ba(N03)2 with distilled water to 1 liter (10 mg Ba/ml)
Ammonium hydroxide, 0.1N (1 volume of concentrated
NH^OH diluted with 150 volumes of distilled water)
-------
Ammonium oxalate, saturated solution: Add enough
(NH02C20«f'H20 to distilled water so that crystals
persist (8 gm/100 ml).
Ammonium acetate buffer solution: Dissolve 154 g of
NH^CaMz in 800 ml of distilled water, add 57 ml of
glacial acetic acid, adjust the mixture to pH 5.5
using glacial acetic or concentrated NHi»OH as needed.
Dilute to 1 liter.
Acetic acid (1+2): Mix 1 volume of glacial acetic
acid with 2 volumes of distilled water.
Ammonium hydroxide, concentrated (specific gravity
0.90)
Nitric acid, fuming (90%)
Nitric acid, concentrated (70%)
Sodium carbonate solution: Dissolve and dilute 124 g
of Na2C03-H20 (or 106 g of Na2C03) with distilled
water to 1 liter (2N solution).
Sodium chromate solution: Dissolve and dilute 117 g
of Na2CrO,».4H20 with distilled water to 1 liter
(0.5M solution).
Sodium hydroxide solution: Dissolve and dilute 240 g
of NaOH with distilled water to 1 liter (6N).
Tributyl phosphate, reagent-grade: Wash by shaking
with an equal volume of 14N nitric acid. Discard the
washings.
Methyl red indicator: Dissolve and dilute 0.1 g of
methyl red to 100 ml with distilled water.
Acid-carrier solution for preservation of samples:
To a 1-liter volumetric flask add 3.86 g of Sr(N03)2
and 3.04 g of Ba(N03)2, add 400 ml of distilled water
-------
and 500 ml of concentrated HN03, swirl the flask to
mix the contents, cool the solution to room tempera-
ture, dilute to volume with distilled water, and mix
thoroughly. For sample preservation in the field,
transfer 50.0-ml portions of the solution to 2-ounce
polyethylene bottles, and cap with poly-seal caps.
This acid-carrier solution should not be stored in
the polyethylene bottles for more than a few days.
50.0 ml of the solution contains 80 mg each of
strontium and barium carriers.
7. Procedures
7.1 Sampling
Sampling is described in "Environmental Radioactivity Surveillance
Guide," published by the U.S. Environmental Protection Agency as report
ORP/SID 72-2. It is recommended that samples be preserved at the time
of collection by the addition of 50 ml of 8N nitric acid containing
80.0 mg each of strontium and barium carriers per 4 liters (or 1 gallon)
of sample collected. However, if determination is to be made of the
strontium-89 and 90 content in the separate dissolved and suspended
fractions of the sample, then those fractions must be separated before
the preservative is added, since the preservative may change the distri-
bution of the sample radioactivity. Rather than separating the dis-
solved and suspended solids fractions in the field, samples can be
brought to the laboratory without preservative added and those samples
should be so labeled. Separation is then done by filtering out the
suspended solids on a weighed 0.45-micrometer pore membrane filter.
The filter is dried, weighed, and set aside for further analysis. The
preservation solution is then added to the filtrate which is returned
to the original sample container and held there for overnight or longer
before analysis is begun.
-------
Note: Samples brought in without preservative added (because dissolved
and suspended fractions are to be separated) may not remain1
completely unchanged as to their fractional radioactivities.
Container wall effects and temperature change could result in
a change in the radioactivity concentrations of the two sample
fractions. When such change is suspected, or when significant
radioactivity is found in the suspended solids fraction, then
another sample should be taken and separation of the two
fractions done in the field.
7.2 Analysis
7.2.1 Strontium-89 and Strontium-90
7.2.1.1 All samples to which have been added acid-carrier preserva-
tive, and whose volumes have not been measured, should now be
measured so that accurate carrier concentrations can be determined.
This is required for later yield determinations. Sample aliquots should
be corrected for the acid-carrier dilution.
For suspended solids fractions that are to be analyzed sepa-
rately, transfer the filter holding the suspended solids to a 250-ml
beaker. Add 2.0 ml each of strontium, yttrium, and barium carriers.
Wet-ash the filter and suspended solids with one or more treatments of
20 ml of concentrated nitric acid plus 2 ml of 30 percent hydrogen
peroxide, evaporating to near dryness with each treatment. Wet-ash
until there is little or no color, or no added color change in the
evaporated solids. Dissolve and dilute the residue to 200 ml using
10 ml of 70 percent nitric acid and 180 ml of distilled water. Filter
the solution through a 0.45-micrometer membrane filter and rinse with
two 25-ml portions of distilled water, adding the rinses to the fil-
trate. Discard the filter- This sample fraction is now ready to treat
with the steps that follow.
8
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7.2.1.2 Transfer 1-liter water sample aliquots to 2-liter beakers,
and the suspended solids wet-ashed solutions to 400-ml
beakers. Heat the samples to boiling and add 80 ml of 6N NaOH, stir,
and add 50 ml of 2N Na2C03 solution. Continue heating to near boiling
for 1 hour with occasional stirring. Then set the beakers aside for at
least 2 hours, allowing the carbonate precipitate to settle.
7.2.1.3 Decant most of the clear supernate and discard it. With the
remainder of the supernate and necessary water washes (ad-
justed to pH 8 with NH^OH), quantitatively transfer the precipitate to
a 50-ml centrifuge tube. Centrifuge at 2000 revolutions per minute
(rpm) for 10 minutes and discard the supernate. This precipitate will
contain the strontium and barium carriers.
7.2.1.4 Dissolve the precipitate by careful dropwise addition of.4 ml
of concentrated nitric acid, heat in a boiling water bath for about
20 minutes with occasional stirring. Cool the centrifuge tube and
contents with cold tap water.
7.2.1.5 Add 20 ml of fuming nitric acid to the centrifuge tube, cool
in an ice bath and stir. Centrifuge at 2000 rpm for 10 min-
utes, and discard the supernate. Supernate will contain sample calcium.
7.2.1.6 Add 4 ml of water to the precipitate, heat in a hot water
bath with occasional stirring to dissolve. Then repeat
step 5.
7.2.1.7 Dissolve the strontium and barium nitrate precipitate in
25 ml of water, add 2 drops of methyl red indicator solution,
neutralize to yellow color with NHitOH, then adjust the pH back to red
color by adding dropwise (1+2) acetic acid.
-------
7.2.1.8 Add 5 ml of the ammonium acetate buffer solution. Heat in
a hot water bath. Add, with stirring, 2 ml of the 0.5M
Na2CrOit solution and digest in the hot water bath for 15 minutes. Cool
the reaction mixture and centrifuge at 2000 rpm for 10 minutes. Trans-
fer the supernate to a clean 50-ml centrifuge tube, and discard the
barium chromate residue (or save for radioactive barium, radium, or
lead analysis).
7.2.1.9 To the buffered chromate supernate add 2 ml of concentrated
NHuOH; heat in a hot water bath; add 5 ml of 2N NazC03 solu-
tion; digest in the hot water bath for 15 minutes; cool; centrifuge,
and discard the supernate.
7.2.1.10 In this step the strontium-89,90 is separated from yttrium-90
with a yttrium carrier scavenge to start a specific ingrowth
period and to get a separate radiostrontium count in the following
steps. Add a few drops of concentrated HNOa to the carbonate precipi-
tate; add 15 ml of water; add 1 ml of the yttrium carrier solution;
add 1 drop of wetting agent solution (such as "Photo-Flo," an Eastman
Kodak Company film processing product); add 5 ml of concentrated HNi»OH;
heat in a hot water bath for 15 minutes with occasional stirring.
Centrifuge and transfer the supernate to a clean 50-ml centrifuge tube.
Wash the yttrium hydroxide precipitate with 5 ml of water, centrifuge
and add this wash to the supernate. Note the time of this yttrium
hydroxide precipitation which marks the beginning of the yttrium-90
ingrowth period. From this point on it is important to proceed without
delay to the final separation and count of the strontium-89 and 90
activity.
7.2.1.11 Add 5 ml of 2N Na2C03 to the supernate from step 10, heat in
a hot water bath for 15 minutes, cool in a cold water bath
for about 10 minutes, centrifuge and discard the supernate.
10
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7.2.1.12 Dissolve the strontium carbonate precipitate with a minimum
amount, of (1+5) nitric acid dropwise. Add 20 ml of water,
1 ml of concentrated NH^OH, and 2 ml of 2N NaC03 solution. Heat in a
hot water bath for 15 minutes, cool for 10 minutes.
7.2.1.13 Transfer the strontium carbonate precipitate quantitatively
to a tared glass fiber filter. Wash the precipitate with
three 10-ml portions of water adjusted to pH 8 with NH^OH, then with
three 10-ml portions of acetone. During filtration and washes of the
strontium carbonate, minimize the time of air flow through the filter
to avoid collection of radon daughters. Dry the filter at 110° C for
10 minutes, then weigh and count (within 2 hours). This count gives
the total of strontium-89 and 90 activities, plus the ingrown yttrium-90.
Note the time of this count as it must be corrected for yttrium-90 in-
growth (time between steps 10 and 13).
7.2.2 Strontium-90 (By Yttrium-90)
7.2.2.1 After counting the strontium carbonate for strontium-89 and
90 activity, store the filter for a measured period of ingrowth
and proceed with the following steps for yttrium-90 separation. A
2-week or longer ingrowth period is recommended for samples with very
low strontium-90 activity. Step 7.2.1.10 was the beginning of this
ingrowth period.
7.2.2.2 Transfer the filter to a small funnel which has been placed
to drain into a 60-ml separatory funnel. Dissolve the stron-
tium precipitate by carefully wetting the filter with 5 ml of 6N nitric
acid. Wet the filter with 2.0 ml of the yttrium carrier solution.
Then rinse the strontium and yttrium into the separatory funnel by
washing the filter with four more 5-ml portions of 6N nitric acid.
11
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7.2.2.3 Rinse the filter and funnel with 10 ml of fuming nitric acid,
collecting the rinse in the separatory funnel. Swirl the
separatory funnel to mix the solution contents.
7.2.2.4 Add 10 ml of the acid-washed tributyl phosphate, stopper,
and shake thoroughly for 3 to 5 minutes. Allow the phases
to separate and transfer the aqueous phase to a second 60-ml separatory
funnel.
7.2.2.5 Add 10 ml of acid-washed tributyl phosphate to the second
separatory funnel. Shake for 3 to 5 minutes, allow the phases
to separate, transfer the aqueous phase to a third 60-ml separatory
funnel.
7.2.2.6 Combine the two tributyl phosphate portions into one separa-
tory funnel and wash twice with 5-ml portions of 14N HN03.
Add these acid washes to the aqueous phase. The aqueous phase contains
the strontium fraction and can be saved for a second ingrowth of
yttrium-90 if so desired. Record this time as the beginning of the
yttrium-90 decay.
7.2.2.7 Extract the yttrium from the tributyl phosphate by shaking
for 3 to 5 minutes with 10 ml of 0.1N HN03. Transfer the
0.1N HN03 phase to a 50-ml centrifuge tube. Repeat the extraction
with another 10-ml portion of 0.1N HN03 and add this extract to the
centrifuge tube. Discard the tributyl phosphate phase.
7.2.2.8 Precipitate the yttrium as hydroxide by adding 10 ml of con-
centrated NH^OH to the centrifuge tube, stirring and heating
for 10 minutes in a hot water bath. Centrifuge at 2000 rpm for 10
minutes and discard the supernate. Wash the precipitate with two 10-ml
0.1N NH^OH washes, centrifuging at 2000 rpm for ten minutes and discard-
ing the washes.
12
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7.2.2.9 Dissolve the precipitate in 15 ml of distilled water contain-
ing 2 ml of HC1 (1+1). Precipitate the yttrium as oxalate by
adding 20 ml of saturated ammonium oxalate solution; heat for 30 minutes
in a hot water bath (near boiling). Cool in an ice bath and then filter
the yttrium oxalate on a tared glass fiber filter. Wash the precipitate
with three 5-ml portions of distilled water, then with three 5-ml por-
tions of ethyl alcohol, and finally with three 5-ml portions of acetone.
Air dry the filter for about 1 hour, then weigh and count for yttrium-90
activity. Record the time of the counting for decay correction (time
between step 7.2.2.6 and count time).
8. Calibration
8.1 Counting Efficiencies
Separate counting efficiencies should be determined for strontium-
89 and 90 using known amounts of the respective radioactivities and
20.0 mg of strontium carrier, precipitated as carbonate and counted. A
strontium-90 precipitate is prepared after separation of the yttrium-90
daughter by the following procedure. Add a known amount of strontium-90
standard, in the order of 1000 disintegrations per minute (dpm), and
20 mg of strontium carrier to a 50-ml centrifuge tube, add 20 ml of
water and proceed as in steps 7.2.1.10 through 7.2.1.13 but omitting
step 7.2.1.12. Then for the yttrium-90 counting efficiency continue
with steps 7.2.2.1 through 7.2.2.9.
9. Calculations and Reporting
9.1 Chemical Yields for Strontium and Yttrium
mg SrC03 recovered
Yield factor for Sr, a =
mg Sr carrier added (as carbonate)
20 mg of strontium is equivalent to 33.7 mg SrC03.
13
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v- I., x . * v u m9 Y2(C2003-9H20 recovered
Yield factor for Y, b =
mg Y carrier added (as oxalate)
9.2 Other Terms for Calculations
c = strontium-90 counting efficiency
d = strontium-89 counting efficiency
e = yttrium-90 counting efficiency
f = yttrium-90 decay factor
g = yttrium-90 ingrowth factor, for unwanted yttrium-90 in
total strontium-89,90 count
h = strontium-89 decay factor
V = volume of sample analyzed, in liters
i = yttrium-90 ingrowth factor for strontium-90 by yttrium-90
determination
9.3 Calculations for Activities at Equilibrium Conditions
Cpm values indicated are net cpm (reagent blank, including back-
ground, subtracted).
Y dpm = !!jLfp = 9°Sr dpm
90Sr. cpm = 90Y dpm x c
Total 89»90Sr cpm = total cpm (SrC03) - ingrown 90Y cpm
Ingrown 90Y cpm = 90Sr dpm x e x g
89Sr cpm = total^Sr cpm _ 9(,Sr cpm _ 9oSr dpm x e x g
89Srdpm =
14
-------
9°
Sr pCi/liter =
"
SrpCi/liter =
Error associated with the results of the analysis should also be re-
ported. See Appendix A for error and statistical calculations. See
Appendix B and C for yttritum-90 decay and ingrowth factors, and
Appendix D for strontium-89 decay factors.
15
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APPENDIX A. ERROR AND STATISTICAL CALCULATIONS
Because of the random nature of radioactivity disintegrations there
is an error associated with any measured count of these disintegrations.
The variability of any measurement is indicated by the standard devia-
tion. The standard deviation in the counting rate is determined by the
following equation:
where R = gross count rate
ti = counting time for the gross count
B = background count rate
tz = counting time for the background count
Let o(Ri) = DI = standard deviation for the count of total 89)90Sr
(from SrCOa precipitate, which includes the unwanted
ingrown 90Y)
Let a(R2) = D2 = standard deviation for the 90Y count for 90Sr
determination
The counting error for a given sample for the 89Sr and 90Sr deter-
minations expressed in pCi/liter are shown as follows:
goo c 1.96 D2 x 1000
Sr> E 2.22abef1V
For 89Sr> E .
16
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where 1.96 = 95% confidence factor
1000 = ml/liter
2.22 = dpm/pCi
a = strontium recovery factor
b = yttrium recovery factor
c = 90Sr counting efficiency
d = 89Sr counting efficiency
e = 90Y counting efficiency
f = 90Y decay factor
g = ingrowth factor for unwanted 90Y in total 89)90Sr count
i = ingrowth factor for 90Y for 90Sr determination
These were derived by applying propagation of error theory to the ex-
pressions in Section 9.3.
The standard deviation of a number of experimental analyses or ob-
servations is determined by:
s
n
-*
^\2
. - n)2/m -
where n. = activity (pCi/liter of a given sample
ri = mean activity (pCi/liter) of a series of analyses
m = the number of replicate analyses
17
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APPENDIX B. YTTRIUM-90 DECAY AND INGROWTH FACTORS (0-72 HOURS)
t (hr)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.0
19.5
20.0
20.5
21.0
21.5
22.0
22.5
23.0
23.5
.-»
1.0000
.9940
.9893
.9839
.9786
.9734
.9681
.9629
.9577
.9526
.9474
.9423
.9373
.9322
.9272
.9222
.9172
.9123
.9074
.9025
.8976
.8928
.8880
.8832
.8785
.8737
.8690
.8644
.8597
.8551
.8505
.8459
.8413
.8368
.8323
.8278
.8234
.8189
.8145
.8101
.8058
.8014
.7971
.7928
.7885
.7843
.7801
.7759
l-e-Xt
.0000
.0054
.0107
.0161
.0214
.0266
.0319
.0371
.0423
.0474
.0526
.0577
.0627
.0678
.0728
.0778
.0828
.0877
.0926
.0975
. 1024
.1072
.1120
.1168
.1215
.1263
.1310
.1356
.1403
.1449
.1495
.1541
.1587
.1632
.1677
.1722
.1766
.1811
.1855
.1899
.1942
.1986
.2029
.2072
.2115
.2157
.2199
.2241
t (hr) e"Xt l-e"Xt
24.0
24.5
25.0
25.5
26.0
26.5
27.0
27.5
28.0
28.5
29.0
29.5
30.0
30.5
31.0
31.5
32.0
32.5
33.0
33.5
34.0
34.5
35.0
35.5
36.0
36.5
37.0
37.5
38.0
38.5
39.0
39.5
40.0
40.5
41.0
41.5
42.0
42.5
43.0
43.5
44.0
44.5
45.0
45.5
46.0
46.5
47.0
47.5
.7717
.7676
.7634
.7593
.7552
.7512
.7471
.7431
.7391
.7351
.7311
.7272
.7233
.7194
.7155
.7117
.7078
.7040
.7002
.6965
.6927
.6890
.6853
.6816
.6779
.6743
.6706
.6670
.6634
.6599
.6563
.6528
.6493
.6458
.6423
.6388
.6354
.6320
.6286
.6252
.6219
.6185
.6151
.6118
.6085
.6053
.6020
.5988
.2283
.2324
.2366
.2407
.2448
.2488
.2529
.2569
.2609
.2649
.2689
.2728
.2767
.2806
.2845
.2883
.2922
.2960
.2998
.3035
.3073
.3110
.3147
.3184
.3221
.3257
.3294
.3330
.3366
.3401
.3437
.3472
.3507
.3542
.3577
.3612
.3646
.3680
.3714
.3748
.3781
.3815
.3849
.3882
.3915
.3947
.3980
.4012
t (hr) e"Xt l-e'Xt
48.0
48.5
49.0
49.5
50.0
50.5
51.0
51.5
52.0
52.5
53.0
53.5
54.0
54.5
55.0
55.5
56.0
56.5
57.0
57.5
58.0
58.5
59.0
59.5
60.0
60.5
61.0
61.5
62.0
62.5
63.0
63.5
64.0
64.5
65.0
65.5
66.0
66.5
67.0
67.5
68.0
68.5
69.0
69.5
70.0
70.5
71.0
71.5
.5955
.5923
.5891
.5860
.5828
.5797
.5766
.5735
.5704
.5673
.5642
.5612
.5582
.5552
.5522
.5492
.5462
.5433
.5404
.5375
.5346
.5317
.5288
.5260
.5232
.5203
.5175
.5148
.5120
.5092
.5065
.5038
.5010
.4983
.4957
.4930
.4903
.4877
.4851
.4825
.4799
.4773
.4747
.4722
.4696
.4671
.4646
.4621
.4045
.4077
.4109
.4140
.4172
.4203
.4234
.4265
.4296
.4327
.4358
.4388
.4418
.4448
.4478
.4508
.4538
.4567
.4596
.4625
.4654
.4683
.4712
.4740
.4768
.4797
.4825
.4852
.4880
.4908
.4935
.4962
.4990
.5017
.5043
.5070
.5097
.5123
.5149
.5175
.5201
.5227
.5253
.5278
.5304
.5329
.5354
.5379
18
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APPENDIX C. YTTRIUM-90 INGROWTH FACTORS (0-27 DAYS)
t (days)
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
3.75
4.00
4.25
4.50
4.75
5.00
5.25
5.50
5.75
6.00
6.25
6.50
6.75
7.00
7.25
7.50
7.75
8.00
8.25
8.50
8.75
l-e-Xt
.0000
.0627
.1215
.1766
.2283
.2767
.3221
.3646
.4045
.4418
.4768
.5097
.5404
.5692
.5963
.6216
.6453
.6676
.6884
.7080
.7263
.7435
.7596
.7746
.7888
.8020
.8145
.8261
.8370
.8472
.8568
.8658
.8742
.8820
.8896
.8864
t (days) l-e"xt
9.00
9.25
9.50
9.75
10.00
10.25
10.50
10.75
11.00
11.25
11.50
11.75
12.00
12.25
12.50
12.75
13.00
13.25
13.50
13.75
14.00
14.25
14.50
14.75
15.00
15.25
15.50
15.75
16.00
16.25
16.50
16.75
17.00
17.25
17.50
17.75
.9029
.9090
.9147
.9201
.9251
.9298
.9342
.9384
.9422
.9458
.9492
.9524
.9554
.9582
.9608
.9633
.9656
.9678
.9697
.9716
.9734
.9751
.9766
.9781
.9795
.9808
.9820
.9831
.9842
.9852
.9861
.9870
.9878
.9886
.9893
.9900
t (days) l-e"Xt
18.00
18.25
18.50
18.75
19.00
19.25
19.50
19.75
20.00
20.25
20.50
20.75
21.00
21.25
21.50
21.75
22.00
22.25
22.50
22.75
23.00
23.25
23.50
23.75
24.00
24.25
24.50
24.75
25.00
25.25
25.50
25.75
26.00
26.25
26.50
26.75
27.00
.9906
.9912
.9917
.9922
.9927
.9932
.9936
.9940
.9944
.9948
.9951
.9954
.9957
.9959
.9962
.9964
.9967
.9969
.9971
.9973
.9974
.9976
.9977
.9979
.9980
.9981
.9982
.9984
.9985
.9986
.9987
.9987
.9988
.9989
.9990
.9990
.9991
19
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APPENDIX D. STRONTIUM-89 DECAY FACTORS (0-59.5 DAYS)(t% = 51 DAYS)
t (days)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.0
19.5
e-Xt
1.0000
.9932
.9865
.9798
.9732
.9668
.9601
.9536
.9471
.9407
.9344
.9280
.9217
.9155
.9093
.9031
.8970
.8909
.8849
.8789
.8729
.8670
.8612
.8553
.8495
.8438
.8381
.8324
.8268
.8212
.8156
.8101
.8046
.7992
.7938
.7883
.7881
.7778
.7725
.7672
t (days) e"Xt
20.0
20.5
21.0
21.5
22.0
22.5
23.0
23.5
24.0
24.5
25.0
25.5
26.0
26.5
27.0
27.5
28.0
28.5
29.0
29.5
30.0
30.5
31.0
31.5
32.0
32.5
33.0
33.5
34.0
34.5
35.0
35.5
36.0
36.5
37.0
37.5
38.0
38.5
39.0
39.5
.7620
.7569
.7518
.7568
.7416
.7366
.7317
.7267
.7218
.7169
.7120
.7072
.7023
.6977
.6930
.6882
.6836
.6790
.6742
.6699
.6651
.6608
.6562
.6519
.6473
.6430
.6388
.6342
.6300
.6259
.6215
.6172
.6131
.6090
.6050
.6009
.5968
.5928
.5888
.5848
t (days) e"Xt
40.0
40.5
41.0
41.5
42.0
42.5
43.0
43.5
44.0
44.5
45.0
45.5
46.0
46.5
47.0
47.5
48.0
48.5
49.0
49.5
50.0
50.5
51.0
51.5
52.0
52.5
53.0
53.5
54.0
54.5
55.0
55.5
56.0
56.5
57.0
57.5
58.0
58.5
59.0
59.5
.5808
.5769
.5730
.5690
.5652
.5613
.5575
.5539
.5500
.5462
.5427
.5380
.5352
.5318
.5280
.5245
.5210
.5175
.5140
.5105
.5070
.5035
.5000
.4967
.4933
.4900
.4868
.4834
.4801
.4769
.4734
.4702
.4671
.4640
.4608
.4578
.4547
.4513
.4484
.4454
20
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/4-76-011
3. RECIPIENT'S ACCESSIOf»NO.
4. TITLE AND SUBTITLE
MEASUREMENT OF STRONTIUM-89 AND STRONTIUM-90 IN ENVIRON
MENTAL WATERS A Tentative Reference Method
5. REPORT DATE
March 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Quality Assurance Branch
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
10. PROGRAM ELEMENT NO.
1HA327
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
13. TYPE OF REPORT AND PERIOD COVERED
14, SPONSORING ApENCY CODE .
EPA-ORD, Office of Monitoring
and Technical Support
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A tentative reference method for the measurement of strontium-89 and -90 in
environmental waters is described. Samples of environmental water sources are
collected, preserved with acid-strontium carrier, and analyzed for strontium-89
and/or strontium-90. Strontium-89 and -90 are separated from the sample water
by precipitating with stable strontium carrier as carbonate. The strontium
carbonate is dissolved, yttrium-90 separated, the strontium reprecipitated as
carbonate, filtered, and counted for the combined strontium-89 and -90 activity.
The yttrium-90 is allowed to grow in from the strontium-90 activity; the
strontium carbonate is redissolved; the yttrium-90 is separated, precipitated,
and counted for the strontium-90 determination. The strontium-89 activity is
then determined by difference of the total strontium-89 and -90 and the separate
strontium-90 activities. Recoveries are determined from the added and found
(recovered) strontium carrier. Counting efficiencies are determined with
prepared standard reference samples. Results are reported in pCi/liter.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
strontium isotopes
yttrium isotopes
calibration
reference standards
quality assurance
standards
radiochemistry
water pollution
07B
14B
14D
18B
8. DISTRIBUTION STATEMENT
Release to the public
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
28
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
4GPO 690*360-1976
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