EASTERN ENVIRONMENTAL RADIATION FACILITY
RADIOCHEMISTRY PROCEDURES MANUAL
Conplled and Edited by
Robert Lieberman
June 1984
U.S. Environmental Protection Agency
Office of Radiation Programs
Eastern Environmental Radiation Facility
P.O. Box 3009
Montgomery, AL 36193
EPA 520/5-84-006
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TECHNICAL REPORT DATA
(Pleat rtad Inttrucrions on the reverse btfort completing)
1 REPORT Nn
F-PA s?n/s-8•». 4-771 oncviou* COITION 11 O«§OL«T«
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FOREWORD
The Eastern Environmental Radiation Facility (EERF) in Montgomery,
Alabama, is a field laboratory operated by the Office of Radiation
Programs of the United States Environmental Protection Agency. Prior to
December 2, 1970, the EERF was known as the Southeastern Radiological
Health Laboratory and operated by the United States Public Health
Service. This manual is the first publication of radiochemical procedures
used at the EERF since the 1965 publication by the Public Health Service
of Procedures for Determination of Stable Elements and Radionuclides in
Environmental Samples (Public Health Service Publication No. 999-RH-10).
Due to the time elapsed since last publication and the EERF's changes in
direction since its incorporation into the Environmental Protection
Agency, a comprehensive manual of analytical procedures used is overdue.
Beyond documentation, our purpose in publishing the manual is to provide a
means of exchanging information with other laboratories and with other
individuals, groups, and organizations working with the Environmental
Protection Agency.
Although other procedures exist for some of the analyses addressed in
this manual, those procedures that we have chosen to publish are those
that we know to be most appropriate and effective for ambient and
environmental levels and, generally, for our needs here at the EERF. All
of the procedures in the manual have been exposed to rigorous intra- and
interlaboratory analytical quality control, and we have strong confidence
in the results that will be obtained using them. Many of the procedures
have been published elsewhere and we make no claim to originality
regarding them. However, we have tried to write and present the
procedures clearly in order to make them useable by the greatest number of
technically competent persons. Finally, by way of assurance, all those
procedures included in this manual that are associated with EPA standards
requiring analysis of radionuclides are certified EPA alternate procedures.
ii
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The manual reflects the careful efforts of many people over nearly
twenty years of work. I would like to acknowledge all of their
contributions. Robert Lleberman deserves special recognition for his
labor over a long period of time In assembling these procedures and
working toward an accurate and consistent presentation of them.
Especially since the material In this manual will be periodically
updated, we would like to Invite and encourage comments, suggestions, and
discussion of the procedures. Remarks should be addressed to the
Director, Eastern Environmental Radiation Facility, P. 0. Box 3009,
Montgomery, Alabama, 36193.
Charles R. Porter, Director
Eastern Environmental Radiation Facility
Montgomery, Alabama
June 1984
Hi
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PREFACE
This manual provides a convenient and accurate reference for the
determination of pertinent radlonuclldes and stable elements in
environmental and bioassay samples. All of the described procedures have
been used routinely in the analysis of many samples. In addition to the
chemical procedures, sections have also been included on radioactivity
counting, standardization, and quality control.
Periodically, the manual will be updated and corrected with new
procedures and sections added. The page numbering system, which is
similar to that of the HASL-300 Procedures Manual, has this end in mind.
Each division in this manual has been given a letter. The first pair of
digits with each letter represents sections of a division and the last
pair of numbers is the pages within the section. In Division C on
Chemical Procedures, the element symbol precedes any numbers, the first
pair of numbers is the specific procedure for that element, and the second
pair is used for the page number. Thus, C-Am-01-01 is page 1 of the first
procedure for americium.
Certain sequential and multielement analyses will be found at the end
of the division under C-00-01, etc.
A-01
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TABLE OF CONTENTS
A. General
A-01 Preface
A-03 Table of Contents
B. General Analytical Chemistry
B-01 Quality Assurance Program
B-02 Instrumentation
B-03 Preparation of Standards for Instrument Calibration
C. Chemical Procedures
Am-01 Radiochemical Determination of Americium-241 in Ashed
Samples Including Soil, Fly Ash, Ores, Vegetation and Biota
C-01 Radiochemical Determination of Carbon-14 in Aqueous Samples
H-01 Radiochemical Determination of Tritium in Milk, Soil, Urine,
Vegetation and Other Biological Samples: Azeotropic Method
H-02 Radiochemical Determination of Tritium in Water: Dioxane Method
H-03 Radiochemical Determination of Tritium in Water Samples:
Emulsion Method
1-01 Radiochemical Determination of Iodine-131 in Drinking Water
1-02 Radiochemical Determination of Iodine-131 in Milk
Kr-01 Radiochemical Determination of Krypton-85 in Environmental
Air Samples
P-01 Radiochemical Determination of Phosphorus-32 in Fish Muscle
P-02 Colorimetric Determination of Stable Phosphorus in Biological
Samples
Pb-01 Radiochemical Determination of Lead-210 in Water and Solid
Samples
Pm-01 Radiochenical Determination of Promethium-147 in Aqueous
and Urine Samples
Pm-02 Radiochemical Determination of Promethium-147 in Feces Ash:
Rapid Method
Preceding page blank
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TABLE OF CONTENTS (Continued)
Pu-01 Radiochenrical Determination of Plutonium in Ashed Samples,
Soil, Coal, Fly Ash, Ores, Vegetation, Biota and Water
Pu-02 Preparation of Plutonium-236 Tracer Solution
Ra-01 Radiochemical Determination of Radium-226 in Solid Samples
Requiring Fusion
Ra-02 Radiochemical Determination of Radium-226 in Urine
Ra-03 Radiochemical Determination of Radium-226 in Water Samples
Ra-04 Radiochemical Determination of Radium-226, Deemanation Procedure
Ra-05 Radiochemical Determination of Radium-228 in Water Samples
Sr-01 Radiochemical Determination of Radiostrontium in Food Ash and
other Solid Samples
Sr-02 Radiochemical Determination of Radiostrontium in Milk
Sr-03 Radiochemical Determination of Strontium-90 in Urine
Sr-04 Radiochemical Determination of Radiostrontium in Water, Sea
Water and other Aqueous Media
Th-01 Preparation of Thorium-234 Tracer Solution
U-01 Preparation of Uranium-232 Tracer Solution
00-01 Radiochemical Determination of Gross Alpha and Gross Beta
Particle Activity in Water
00-02 Radiochemical Determination of Gross Alpha Activity in Drinking
Water by Coprecipitation
00-03 Radiochemical Determination of Lead-210 and Polonium-210 in Dry
Inorganic and Biological Samples
00-04 Radiochemical Determination of Plutonium, Thorium and Uranium
in Air Filters
00-05 Radiochemical Determination of Thorium and Uranium in Ashed
Samples Including Soil, Coal, Fly Ash, Ores, Vegetation and
Biota: Fusion Method
00-06 Radiochemical Determination of Thorium and Uranium in Ashed
Samples: Nonfusion Method
00-07 Radiochemical Determination of Thorium and Uranium in Water
A-04
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QUALITY ASSURANCE PROGRAM
Introduction
The quality assurance program 1s a separate entity at the Eastern
Environmental Radiation Facility (EERF), removed organizationally from the
functional groups It serves, the Monitoring and Analytical Services Branch
and the Environmental Studies Branch. The main purpose of the EERF
quality assurance program is to establish limits of acceptable
radioanalytical results and to assure that analytical results stay within
these error limits. When analytical results deviate from established
limits, appropriate laboratory personnel determine the cause and take
immediate remedial action. The need for a quality assurance program is
underscored by the fact that established limits are not fixed. They
change as new technologies and procedures develop.
Program Functions and Responsibilities
Preparation of Standard Radioactive Sources and Solutions
Quality assurance personnel, coordinating with counting room
personnel, stock appropriate radioactive standards and prepare the
standards in various counting geometries for instrument calibration. The
primary source of radioactive standards is the Environmental Protection
Agency (EPA) National Quality Assurance Program at the Environmental
Monitoring and Support Laboratory, Las Vegas, Nevada (EMSL-LV). Other
sources include the National Bureau of Standards (NBS) and commercial
suppliers of certified standards. Table 1 describes the standards
required for each type of radloassay and the minimum frequency of each
calibration. Table 2 lists the nominal radioactivities for these
calibration standards.
Counting room personnel calibrate the instruments and perform the
B-01-1
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stability checks, and quality assurance personnel verify the results of
the checks for specified performance. The Environmental Studies Branch
calibrates and maintains the field measurement and sampling equipment, and
quality assurance personnel supply the appropriate standards as required.
(Table 3 lists the types of field equipment used at the EERF and their
calibration frequencies.) In addition, quality assurance personnel
prepare solutions containing known quantities of various radlolsotopes as
needed by analytical personnel to validate or modify radlochemical
procedures.
Intrafacility Cross-Check Program
Four types of samples are analyzed in the EERF cross-check analysis
program. Routinely, every tenth sample through the laboratory is analyzed
in duplicate. In addition, each week a 'spiked1 sample and a 'blind1
sample are analyzed. A spiked sample Is one which has not been previously
analyzed and which has had added to it a measured quantity of at least one
radioisotope that is routinely analyzed at the laboratory. A blind sample
is a sample of material that has been previously analyzed but whose
identity is unknown by the analyst at the time of reanalysis. Finally,
the cross-check program includes periodic analyses of samples to determine
background levels of radloisotopes. Table 4 outlines the intrafacility
cross-check program. The Computer Services Section maintains all data
generated from this program in the central data repository.
Interlaboratory Cross-Check Program
Quality assurance personnel participate In three interlaboratory
programs. The first and most comprehensive program Is the EPA National
Quality Assurance Program at the Environmental Monitoring and Support
Laboratory, Las Vegas, Nevada (EMSL-LV). Tables 5 and 6 describe the
EMSL-Las Vegas cross-check program. Table 5 lists the available
cross-check samples, and Table 6 shows the distribution schedule.
"Environmental Radioactivity Laboratory Intercomparlson Studies Program",
1978-1979, (EPA 600/473-032) describes this program 1n further detail.
B-01-2
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The second interlaboratory program in which EERF quality assurance
personnel participate is the intercomparison analysis studies conducted by
the World Health Organization (WHO) and the International Atomic Energy
Agency (IAEA). Participation in these studies is limited to the
analytical disciplines represented at the EERF. During the year, the EERF
receives four or five samples consisting of specific radioisotopes in
various materials.
Finally, the EERF participates fn periodic Intercomparison analysts
studies. These studies are usually brief and involve specific
radioisotopes in a particular sample medium. Such analyses are usually
done by specific request to the EERF. Requests originate from other
government agencies and, on occasion, from professionals In the private
sector.
In addition to the above three programs, the EERF, on an as-needed
basis, utilizes reference materials made available by other agencies. The
NBS, WHO, IAEA, and EMLS-LV, for example, often make reference materials
available. EERF quality assurance personnel procure these materials
whenever lab personnel determine a reference need.
Data Storage
The Computer Services Section stores all data pertaining to the
quality assurance program. The kinds of data that are stored include the
following:
-all intrafacility and interfacility comparison analyses results
with related performance
-all data related to reagent blanks, Instrument backgrounds, chemical
recoveries, Instrument counting efficiencies, and instrument
calibration
-all replicate sample analyses results
Analytical Performance Review
Quality assurance personnel continuously review all data relating to
B-01-3
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the radioanalytical performance of the EERF. When they find variances
from control limits, they notify supervisory personnel who review all
pertinent data and procedures. If necessary, the laboratory tests
procedures to identify causes for the variances. Subsequently, quality
assurance personnel institute modifications, if necessary, to assure that
similar variances will not recur. Pvery two years the EERF publishes a
report that reviews and discusses results of its quality assurance program
(ORP/EERF-79-2).
Support Functions By Other EERF Staff
To be successful, the quality assurance program requires the support
and cooperation of personnel in other units of the laboratory. These
support tasks and responsibilities, according to personnel category,
include the following:
-Counting room personnel conduct daily stability checks and frequent
background counts and calibrate all instruments. Proper records of
these checks are maintained in the counting room.
-Analytical chemistry personnel repeat the analysis of one sample for
every 10 samples analyzed (replicate analyses) and analyze at least
one reagent blank for every 20 samples analyzed. They maintain the
established procedure for sample identification. All radiochemical
methods are used by facility personnel as they appear in the manual.
Personnel conduct all radiochemical procedures as documented and
modifications to the procedures are not permitted without approval by
the laboratory director and notification of quality assurance
personnel. Computations are monitored for accuracy by spotchecks.
-Computer services personnel periodically review the accuracy of
electronically computed results, evaluate results for proper error
terms, maintain the state-of-the-art methodology for analytical
computations consistent with available computer capabilities, and
B-01-4
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maintain the central data repository.
References
1. Kanipe, L.G., Handbook for Analytical Quality Control and
Radioanalytical Laboratories, EPA-600/7-77-088, August 1977.
2. Blanchard, R., Broadway, J. and Moore, J., The Eastern Environmental
Radiation Facility's Participation in Interlaboratory and
Intralaboratory Comparisons of Environmental Sample Analyses: 1979
and 1980, EPA 520/5-82-012, January 1982.
B-01-5
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TABLE 1
Description of Required Radioassay Standards and Calibration Frequencies
Gamma Ray
Systems
Beta Particle
Systems
Alpha Particle
Systems
Liquid
Scintillation
Radon
Emanation
Standards
required
DO
O
CTl
standard
radioisotope
solutions (1-liter
and 3.5-liter
predetermined weights
of strontium carbonate
and yttrium oxalate
precipitates with known
Marinelli beakers) amounts of °9Sr, 90Sr,
anH 90V
and
specific isotope analysis:
standard solutions of
238-234y an(| 239pu
on planchets
gross alpha analysis:
standard uranium solutions
and self-absorption
standards
radiation
standards in
aqueous
solutions
standard
226Ra
solutions
Calibration annually
frequency
quarterly
monthly (for specific
Isotope analysis)
3H (biannually) annually
222Rn (biannually)
14C (annually)
NOTE: Table 2 lists the nominal radioactivities for calibration standards.
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TABLE 2
Nominal Activities of Radlonucllde Standards for Gamma Ray Efficiencies
CO
I
o
I
~o
dpm/ sample
Cylindrical Nal Crystal*
Rad1o1sotope
40K
51Cr
54Mn
58Co
59Fe
60Co
65Zn
95zr/95Nb
106Ru
HOmAg
124Sb
ISlj
134Cs
400 ml
50 g KC1**
1 x 105
5 x 10*
5 x 104
1 x 105
7 x 10*
1 x 105
3 x 104
1 x 105
5 x 104
5 x 104
1 x 105
5 x 104
1 liter
100 g KC1
1 x 105
5 x 104
5 x 104
1 x 105
7 x 104
1 x 105
3 x 104
1 x 105
5 x 104
5 x 104
1 x 105
5 x 104
3.5 liter
200 g KC1
1 x 105
5 x 104
5 x 104
1 x 105
1 x 104
2 x 105
6 x 104
1 x 105
5 x 104
5 x 104
1 x 105
5 x 104
Nal Crystal
40, 85 ml
20 g K2C03***
1 x 105
5 x 104
5 x 104
1 x 105
7 x 104
1 x 105
3 x 104
1 x 105
5 x 104
5 x 104
1 x 105
5 x 104
40, 85 ml
20 g K2C03
1 x 105
5 x 104
5 x 104
1 x 105
7 x 104
1 x 105
3 x 104
1 x 105
5 x 104
5 x 104
1 x 105
5 x 104
Ge(Li)
400 ml
50 g KC1
1 x 105
5 x 104
5 x 104
1 x 105
7 x 104
1 x 10s
3 x 104
1 x 105
5 x 104
5 x 104
1 x 105
5 x 104
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TABLE 2—Continued
Nominal Activities of Radionuclide Standards for Gamma Ray Efficiencies
CO
I
o
03
dpm/sample
Cylindrical Nal Crystal*
Radioisotope
137QS
140ga/140L^
144Ce/144pr
226Ra
232Tn
400 ml
5 x 104
3 x 104
3 x 105
1 x 105
4 x 104
1 liter
5 x 104
3 x 104
3 x 105
1 x 105
4 x 104
3.5
5 x
3 x
3 x
1 x
4 x
liter
104
104
105
105
104
Nal Crystal
40, 85 ml
5 x 104
3 x 104
3 x 105
1 x 105
4 x 104
40, 85 ml
5 x 104
3 x 104
3 x 105
1 x 105
4 x 104
Ge(Li)
400 ml
5 x 104
3 x 104
3 x 105
1 x 105
4 x 104
* Crystal is 10 cm diameter and 10 cm in height.
** There are 966 dpm 4°K per gram of KC1 that yield 106 (11 percent) 1.46 MeV photons/min.
***There are 1043 dpm 40K per gram of 1(3 C03 that yield 115 (11 percent) 1.46 MeV photons/min.
NOTE: Nominal activities are those that are sufficient to accumulate enough counts in a short period of time
without excessive instrument dead time.
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TABLE 3
Calibration of Field Equipment
Type of Equipment Calibration Frequency
Air monitoring calibration equipment Annually
Air pumps for ERAMS stations Prior to shipment and
annually thereafter
Thermoluminescenee dosimeters (TLD's) Annually
Pressurized ionization chambers (PIC's) Annually
TABLE 4
Intrafacility Comparison Program
Radioisotope Sample Media* Analysis
Selected gamma-ray water, milk, solids Nal, Ge(Li) or both
emi tters
89Sr, 90Sr, or both water, milk, solids specific analyses or
gross beta
Selected actinides water, milk, solids specific analyses or
gross alpha
222Rn water specific analyses
226Ra water, solids specific analyses
3H water, milk specific analyses
14c milk specific analyses
* The prepared samples are rotated randomly to provide at least one
intercomparison per week. These intercomparisons could either be previously
analyzed samples for which contents are known or specially prepared spiked
samples.
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TABLE 5
Summary of EMSL-LV Cross-Check Programs
Sample
Milk
Water
a, Gross
o alpha
r beta*
0
Ganma
3H
239Pu*
Ra
Analysis
89Sr, 90Sr> 131I§
137C;, 140ja> K
Gross alpha, beta.
60co, 106Ru,
1 ^A 1 ^7 5 1
wS 9 V*Sj l/lj
3H
239Pu
226Ra> 228Ra
Activity
Per Isotope
< 200 pCi/ liter
< 100 pC1/liter
< 500 pCi /liter
< 3500 pCi/liter
< 10 pCi/liter
< 20 pCi /liter
Quantity
Supplied
- 4 liters
" 4 liters
~ 4 liters
- 50 ml
~ 4 liters
" 4 liters
Preservative Distribution
Formalin Quarterly
0.5M HN03 Bimonthly
0.5M HN03 Bimonthly
none Bimonthly
0.5M HN03 Semi annually
0.5M HN03 Quarterly
Time for
Analysis
and Report
6 weeks
4 weeks
4 weeks
4 weeks
8 weeks
8 weeks
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TABLE 5-Continued
Summary of EMSL-LV Cross-Check Programs
Sample Analysis
Sr 89Sr, 90Sr
Blind Any Combination of
CO
o
L Air Filter Gross aloha beta*
90Sr, 13?Cs
Soil* 238pu 239pu
ZfflS; 230^, 232Th
Diet 89crj 90cr, 131!
137Cs, 140Ba> K
Activity Quantity
Per Isotope Supplied Preservative
< 50 pCi/liter " 4 liters 0.5M HN03
< 200 pCi/liter " 4 liters 0.5M HN03
< 200 pCi/sample 3 - 5 cm. dia. none
air filters
< 50 pCi /sample "35 grams none
< 50 pCi /sample 2 - 4-liter Formalin
samples
Time for
Analysis
Distribution and Report
Tri annually 8 weeks
Semiannually 10 weeks
Quarterly 6 weeks
Semiannually 8 weeks
Tri annually 8 weeks
* Laboratories must have the necessary licenses before receiving these samples.
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TABLE 6
EMSL-LV Cross-Check Sample Distribution Schedule
(Numbers indicate week of the month)
Month
Water
00
I
o
Oct
Nov
Dec
Jan
Feb
Mar
gamma
Gross alpha
beta
226Ra 89Sr
228Ra 239Pu 90Sr Blind*
Milk
Food
Sr Sr
gamma gamma
Air Filter Soil
Gross alpha,
beta, 137Cs,
89Sr
Pu,
Th
Apr
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TABLE 6--Continued
EMSL-LV Cross-Check Sample Distribution Schedule
(Numbers indicate week of the month)
Month
Gross alpha
gamma beta
00
o
L May 3
to
Jun 1
Water
226Ra 89$r
3H 228Ra 239Pu 90Sr Blind*
1
2 3
Milk Food Air Filter
Gross aloha,
Sr Sr Jjgta, Cs,
gamma gamma "'Sr
4
Soil
Pu,
Th
2***
Jul
Aug
Sep
1
* Performance sample for the Water Supply Laboratory Certification Program.
** Thorium analysis only.
***Plutonium analysis only.
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INSTRUMENTATION
Beta Particle Counting - Low Background
Instrumentation
The beta counters are of the low-background, multiple-detector type
with one or more sample detectors per unit. Steel or lead shielding is
used to attenuate external gamma radiation. Guard detectors operating in
anti-coincidence with the sample detectors reduce the background
contribution due to cosmic interactions. The sample detectors are
gas-flow, window-type Geiger counters, approximately 5 cm in diameter.
The counting gas is a mixture of 99.05 percent helium and 0.95 percent
isobutane. The beta counters are equipped with preset timers. AIT
samples are placed in 5 cm diameter stainless steel planchets for counting.
Operating Voltage
The voltage on the detector necessary for proper operation is
determined by running the "plateau curve" of count rate versus high
voltage. The correct operating voltage is selected in one of the
following two ways:
1. The Initial operating voltage.
A. With check source of known value 1n place, Increasingly
higher voltage Is applied to the detector until it begins to
count.
B. At the point where it begins to count, a one minute count is
recorded.
C. The voltage is increased an integral amount that is
convenient such as 20 or 50 volts.
D. Another one minute count is recorded.
E. Steps C and D are repeated until two consecutive readings are
obtained that lie within the same two sigma region. The
proper operating voltage is the higher voltage of these two
points.
B-02-1
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F. Eleven one minute counts are made to determine whether all
counts do lie within the two sigma area.
G. If more than one count lies outside the two sigma area, the
operating voltage is biased in the opposite direction of the
outliers. (Lower if high and higher if low).
H. In this event the check source is recounted at the new
operating voltage for eleven one minute counts to determine
whether these eleven points lie Within the two sigma area.
2. The monthly check of the operating voltages for detectors in
operation:
A. With check source in place a one minute count is recorded.
B. The operating voltage is lowered by the normal metering
increment for that instrument and another one minute count is
recorded.
C. This procedure is continued until the count rate of the check
source falls below the two sigma area.
D. This procedure indicates that the instrument is functioning
properly and the operating voltage is then reset to the
second voltage increment into the two sigma region.
E. The check of the operating voltage is completed by repeating
IFand 1H above.
WARNING
Do not apply a voltage to a detector to make it go into a
saturated discharge condition. This causes two problems: (1) the
60 gauge wire in the detector becomes oxidized, overheated, and
possibly misshapen due to warping or sagging, and (2) the high
voltage power supply becomes overloaded, which may damage some of
its components.
The correct operating voltage should be determined at least once each
month, after the gas supply is changed, after any electronic maintenance,
or after any modification is made on a detector. Any appreciable change
B-02-2
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In the operating voltage, plateau length, or plateau slope indicates
possible trouble in detector electronics or in the counting gas. It is
desirable not to interrupt the gas flow for any reason, but, if that is
not possible, as when the counting gas is changed on a counter, purge the
detector for several hours before applying high voltage to the detectors
and guard.
Counting Efficiency
Counting efficiency is the relationship between sample disintegration
rate and sample counts recorded by the counter. Counting efficiency is
usually expressed as counts per disintegration or as the percentage of
disintegrations recorded as counts. Counting efficiency may also be
expressed as the count rate per unit of radioactivity, i.e., cpm per
pCi/1.
Counting efficiency is determined by placing a source with a known
disintegration rate or known radioactivity in the beta counter and
measuring its count rate. This source is referred to as a standard
source, and the process of determining the counting efficiency Is called
calibration. Calibration should be performed for each radionuclide that
will be counted in the counter, and the standard sources should be of the
same physical form (size, shape, chemical composition, planchet material,
etc.) as the samples to be counted. Gross beta calibration is performed
using a standard source of strontium-90 plus yttrium-90 in equilibrium.
The results of a gross beta determination of a sample is then reported as
activity equivalent to strontium-90 plus yttrium-90 in equilibrium. (See
Standardization Section for preparation of standards.)
Beta counters should be calibrated every four to six months and after
mechanical modifications are made on a detector. The daily operational
check procedure as outlined below serves also as a check on the relative
counting efficiency.
B-02-3
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Background Determination
The background counting rate of the low-background beta counters Is
usually between 0.5 and 1.5 counts per minute. It can vary from detector
to detector and from day to day. The background for each detector should
be determined with an overnight measurement and at the beginning of the
workday for the length of time that routine samples are counted (or
another specific time) and should be measured using a clean, empty
planchet in each counter. Radon fluctuations 1n the atmosphere will
affect the background count rate of the beta detector.
Absorption Factor
The beta counting efficiency Is determined using an essentially
weightless standard source. In many types of samples there Is a
sufficient amount of solids so that the sample partially shields Itself
and produces 'self-absorption1. In this case, the count rate obtained on
the sample Is not as great as It should be and must be corrected for
self-absorption according to the weight, or more correctly the
2
'density-thickness' (mg/cm) of the sample.
The absorption correction factors should be determined for the
specific radlonucllde being counted and for approximately the same
chemical composition as In the actual sample. A curve of the absorption
correction factor versus sample weight or density-thickness can be
obtained by preparing a sample that contains equal concentrations of
radioactivity per unit weight of solids and varying amounts of solids
(solids content should vary from approximately zero solids to a weight
equal to the maximum weight expected In an actual sample). Be sure that
the radioactivity Is uniformly distributed In the solid material. The
count rate per unit weight of solids for each sample 1s then divided by
the count rate of the weightless sample, and this fraction Is plotted as a
function of the sample weight. It Is not necessary to use a calibrated
solution for this study since all values are compared to the weightless
sample value.
B-02-4
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Sample Handling
All samples should be handled with care to prevent accidental loss of
the material in the planchet, contamination of the counting room, or
contamination of the beta counters. All samples should be kept covered
when not actually in a counter to keep dust from the samples. Samples
whicli tend to be hygroscopic should be kept in a desiccator until
counted. Planchets that have material piled above the top edge of the
wall or have material on the outside of the planchet should not be placed
in the beta counters. Some types of samples consist of a precipitate on a
2.5-cm diameter filter. The filter should always be in the center of the
5 cm planchet when the planchet is being placed into the counter. Care
should be exercised that the filter not warp or the use of a metal ring
may be necessary.
Counter Operation Check
At the beginning of each workday, a standard check source should be
counted to determine that the counter is operating satisfactorily. The
count obtained each day should be compared with the usual count of the
check source "or that particular detector. A count significantly higher
or lower than the usual value indicates detector or electronic malfunction
or insufficient counting-gas supply. A graph of the daily check source
counts showing the acceptable limits of variation is desirable.
Sample Types and Counting Times
Table 1 gives the types of samples counted for beta activity,
counting times, and general remarks pertinent to each sample type.
Alpha particle Counting - Internal Proportional Counters
Instrumentation
The alpha counters are the internal proportional gas-flow type and
are operated oh the alpha plateau in the proportional region. The
B-02-5
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counting gas is 'P-101, a mixture of 90 percent argon and 10 percent
methane. The detectors are hemispherical with approximately 6.3 cm
diameters. After insertion of each sample, the detector must be purged
for approximately four minutes before the count is started.
Operating Voltage
The plateau curves for the alpha counters are obtained in the manner
described in Part A above. In addition, to assure that the counter is on
the alpha plateau rather than the alpha and beta plateau, a beta standard
is counted in the chamber. The voltage on the detector is lowered until
it counts only alpha disintegrations and the alpha plateau curve is
obtained in this region.
Counting Efficiency
The standards used to determine alpha counting efficiencies should
approximate the samples to be counted in physical size and backing
material. Comments found in Part A apply. Natural uranium (in
equilibrium) or a specific alpha emitter such as piutonium-239 may be used
as the calibration source.
Background Determination
The background counting rate of the alpha counters varies from 0.03
to 0.20 count per minute, depending upon the particular counter. Each
afternoon the plane het holder is cleaned and an overnight background is
obtained in each counter. If the background exceeds the normal background
count, the chamber is decontaminated as outlined below.
Self-Absorption Factor
Because an alpha particle is readily stopped in matter, the number
reaching the sensitive volume of the detector Is greatly reduced by
/
self-absorption and scattering in the sample material. To correct for
this, it is necessary to determine the self-absorption factors for alpha
B-02-6
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counting. Alpha self-absorption factors are determined In the same manner
as the beta self-absorption factors. Samples are prepared containing
equal concentrations of alpha radioactivity per unit weight and varying
amounts of solids, and the count per unit weight 1s plotted as a function
2
of the solids weight (ing) or 'density-thickness* (mg/cm ). The samples
used to determine self-absorption should resemble the actual samples as
much as possible In physical size, planchet material, and chemical
composition, and the alpha emitter should be the same as used to determine
alpha counting efficiency.
As it is usually not practical to prepare a 'weightless1 alpha sample
in the laboratory, the self-absorption curve may be extrapolated to find
the count rate at zero density-thickness. If a standard solution 1s used
to prepare the self-absorption samples, the weightless sample counting
efficiency is determined from the extrapolated count rate at zero
density-thickness. The self-absorption factors are computed by dividing
each count rate per unit weight by the extrapolated weightless sample
count rate. The self-absorption factors thus computed may be plotted as a
function of either total sample weight (mg) or density-thickness
2
(mg/cm ) to obtain the self-absorption curve.
Sample Handling
The comments as given for beta counting apply here.
Counter Operation Check
The same procedure is followed here as outlined for beta counters.
Decontamination
Because the alpha samples are placed Inside the detector, an Internal
proportional detector may easily be contaminated. Approximately every six
months, or at any time the background increases above the level normally
encountered, the detector should be removed and thoroughly cleaned with
ethanol. A brown film often appears on the walls of the detector. This
B-02-7
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film should be removed by lightly rubbing with an abrasive. Soap pads are
routinely used at this laboratory. The manufacturer suggests the use of
an abrasive (HMC proportional counter manual). The center wire should be
cleaned by dipping in ethanol (with care not to bend it out of its normal
shape). The accumulation of this deposit on the chamber walls leads to a
gradual deterioration in performance (generally observed as an increasing
operating voltage, change in plateau slope, and decreasing plateau
length). A sudden deterioration in performance usually indicates
mechanical damage to the center wire or an accumulation of dust or debris
on the center wire.
Sample Types and Counting Times
Table 2 gives.the types of samples counted for alpha activity,
counting times, and general remarks pertinent to each sample type.
Gamma Ray Spectroscopy
Sample Preparation
All samples are usually gamma scanned for specific gamma ray-emitting
nuclides before they are processed, i.e., they are gamma scanned in the
'raw1 form as received at the laboratory. The only preparation required
is to make sure the sample is homogeneous and is in calibrated
configuration. For solid media it is necessary to grind and blend the
sample before counting. Normally a 3.5- or 1.0-liter aliquot of the
homogeneous sample is placed in a clean, polyethylene, Marinelli-type
beaker and analyzed by gamma ray spectroscopy.
Instrumentation
The gamma ray spectrometer consists of a detector, multichannel pulse
height analyzer, data read-out device, and auxiliary instrumentation. The
detectors used here are 10 x 10 cm Nal(Tl) solid or 12.7 x 10 cm well
crystals coupled to photomultiplier tubes and enclosed in steel
B-02-8
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cave-type shields. The Marine!li-type beaker containing the 3.5-liter
sample is placed over the detector inside of the shield.
Calibration
Two types of calibration are required in gamma ray spectroscopy:
gamma ray energy vs. channel number and gamma-counting efficiency.
Knowledge of the energy-channel number relationship permits qualitative
identification of specific gamma ray-emitting nuclides. In order to make
a quantitative determination of the amount of a particular nuclide, it is
necessary to know the counting efficiency and the shape of the standard
spectrum for that nuclide.
Gamma ray energy-channel number relationship. The spectrometers are
used with two energy-channel number relationships. For most of the
samples from routine programs, 200 channels of an analyzer are used to
cover the energy range from 0 to 2 MeV, at 10 keV per channel. The
spectrometers are aligned to the proper energy-channel number relationship
by counting several nuclides with gamma ray energies in the energy range
of interest (0 to 2 MeV) and plotting the location (channel number) of
each peak as a function of the known gamma ray energy. Varying the gain
of the amplifier in the analyzer changes the slope of this line and, in
effect, changes the energy-channel number relationship by a constant
factor (multiplier). Increasing the gain by a factor of 2 changes the
slope by a factor of 2 and changes the energy calibration by a factor of
2. Thus, a peak which initially was located in channel number 10 would
now appear in channel number 20. This relationship is true only if the
plot of channel number versus gamma ray energy passes through the origin
(zero). The threshold control changes the X-axis intercept and permits
one to adjust the spectrometer so that the line passes through the
origin. Often it will be necessary to adjust the threshold, .adjust the
gain, readjust the threshold, readjust the gain, and so forth, to achieve
perfect calibration.
B-02-9
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Most multichannel analyzers exhibit some nonlinearity, that Is, a
plot of photon energy versus channel number will not result In a perfectly
straight line. This is most apparent in the lower energy portion of the
spectrum (< 100 keV). A procedure commonly used is to make Co (1.332
MeV) and 137Cs (0.662 MeV) fall in channels 133.2 and 66.2 by adjusting
the gain and threshold controls. The other nuclides are then counted and
the peak channels determined and plotted against energy. A list of
nuclides used for standardization is shown in Table 3.
Gamma ray counting efficiency. The counting efficiency and spectrum
shape must be determined for each of the nuclides that one desires to
measure quantitatively. Counting efficiency is usually expressed in units
of counts per minute in a selected spectral region per picocurie or counts
per minute per picocurie per liter. A known amount of activity of a
particular nuclide is diluted to the desired volume with distilled water,
thoroughly mixed, placed in a Marine!li beaker, and counted. This
standard solution should be counted for a sufficient length
of time to obtain a total count which will yield good counting
statistics. A total count (in the spectral region of interest) of
approximately 10,000 counts is adequate if only the photopeak efficiency
is to be determined.
Geometries in use at this laboratory are 3.5- and 1.0- liter
Marinelli beakers and a 400-ml plastic container for use with the 10 x 10
cm solid crystals and 40- and 85-ml plastic vials for use with the
12.7 x 10 cm well crystal.
(3) To obtain standard spectra for the analyses of data, it is
necessary to prepare samples with standards of the radionuclides of
interest in the required geometries. It is desirable but not always
practical to duplicate as closely as possible the sample density with the
standards. These spectra should contain statistically sufficient net
counts in each region of interest upon which to base the interference
coefficients and photopeak efficiencies. Table 4 presents typical
photopeak efficiencies for the three geometries in use at this laboratory.
B-02-10
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Routine Counting Procedure
(1) At the beginning of each workday, small cesium-137 and cobalt-60
standards (point sources) are counted for 5 minutes in a uniform
geometry. From the location of the peaks, the energy alignment of the
spectrometer is checked and adjusted, if necessary. A check on counting
efficiency is obtained by comparing the counts in selected spectral
regions to the usual counts for these sources. A plot of these daily
counts on a control chart as a function of data will indicate sudden
degradation in counting efficiency as well as long-term changes in
efficiency, if such should occur. Radioactive decay of the standards
must, of course, be taken into consideration. This daily procedure also
checks out the operation of the complete spectrometer system, including
the data read-out device.
(2) After checking the energy alignment and counting efficiency of
the spectrometer system, a background count is made on each detector using
a sample of distilled water having the same geometry as the samples to be
counted. The background should be counted for the same length of time as
the samples or, preferably, longer.
If the background is to be subtracted automatically by the
spectrometer, the background data should be stored in the spectrometer in
the subtract mode. If background is not to be automatically subtracted,
the background is stored in the add mode, printed out, and erased from
analyzer memory. The background must be scrutinized to determine that it
is normal and that there is no evidence of contamination of the detector
or shield.
(3) The beaker containing the sample is placed in position and
counted for an appropriate length of time. A 50-minute counting time is
normally used.
Analysis of Spectral Data
The analysis of the spectral data obtained from the gamma ray
spectrometer is an important and usually the most complicated aspect of
B-02-11
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the use of this instrument to measure radionuclide concentrations. If one
is interested in only a qualitative determination of the radionuclides in
a sample, i.e., identification of the gamma ray emitters, then the
location of the peaks in the spectrum is of primary interest. If one
desires to determine the amount of a particular nuclide in the sample,
then the location of the peaks, the number of counts in the peaks, and the
interference of one peak with another all must be considered. A number of
methods have been used for analyzing gamma ray spectral data. Two of
these methods in general use are described below. Both are suitable for
use with a desk calculator.
Stripping method. In this method, the spectrum of each radionuclide
is successively stripped from the composite spectrum of the sample.
Beginning with the nuclide having the highest energy photopeak, the
amount of this nuclide is first determined. The standard spectrum of this
nuclide is then normalized to the high energy photopeak in the sample
spectrum and the normalized standard spectrum is subtracted channel by
channel from the sample spectrum. Having removed the spectrum of the
highest energy gamma ray-emitter from the composite spectrum, the next
highest gamma energy photopeak is selected, the amount of radioactivity
determined, the standard spectrum for this radionuclide normalized to the
sample spectrum, and the spectrum of this radionuclide stripped from the
composite spectrum. This procedure is continued until all identifiable
radionuclides present in the sample have been quantitized. It should be
noted that the stripping method is most useful in the case when only a few
gamma ray-emitting nuclides are present in the sample. Also, if there is
direct interference between the photopeaks of different nuclides, the
stripping method becomes somewhat inaccurate. A further disadvantage is
that if a particular nuclide has more than one gamma ray, usually the
highest energy gamma ray must be used as the normalizer and, in some
cases, the photopeak from this gamma ray may be extremely low compared to
other peaks in the spectrum. The errors associated with each successive
B-02-12
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'strip1 are cumulative, causing the error to be great in the lower energy
end of the spectrum.
If only one gamma ray-emitting radionuclide is present in the sample,
the amount of the radionuclide may be determined directly from the net
count (gross count - background) in the selected photopeak region. The
same spectral region must be used in the sample spectrum as was used in
the standard spectrum when counting efficiency was determined.
If only three or four gamma ray-emitting nuclides are present in the
sample and if their photopeaks are separated in energy, a simplified
stripping procedure may be used. The simplified procedure consists of
subtracting the Compton spectrum of higher energy gamma rays from the
photopeak of the lower energy gamma rays. In most cases, the Compton
spectra are approximately straight lines in the regions of the lower
energy photopeaks, that is, the counts do not vary greatly from one
channel to the next. Thus, a straight line is drawn across the base of the
photopeaks of interest and the counts above this baseline are taken as the
counts due to the nuclide of interest. This procedure is applied to a net
spectrum, that is, after the background has been subtracted. The
following formula describes the procedure:
(Gross counts in (Counts due
spectral region - (Background - (Baseline = to nuclide
of interest) counts) counts) of interest)
Matrix (simultaneous solution)-method. The matrix method is similar
to the stripping method in that the interference of the spectrum of one
nuclide with that of another is considered, but the interferences are
subtracted simultaneously rather than successively, as in the stripping
method. Interference in regions of energy higher than the photopeak are
considered as well as the interference in regions of lower energy. Cases
of direct interference of photopeaks also can be handled by this method.
The paper by Kahn et al. (Ref. 2) and the U.S. Public Health Service
training course manual Radionuclide Analysis by Gamma Spectroscopy
(Ref. 3) give a detailed discussion of this method.
B-02-13
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In general, equations are set up describing the contribution of each
radionuclide to the counts in a selected spectral region of interest. The
number of equations corresponds to the number of nucTides. The
contributions of each nuclide to a given spectral region are determined
from the individual spectra of standard sources. The set of equations is
then solved simultaneously. Such simultaneous solutions are most easily
performed by a computer when the number of nuc1 ides (and hence the number
of equations) is more than two or three. The solutions of the set of
equations are then new equations that give the count due to each nuclide
of interest in terms of the observed counts in each spectral region and
constant factors. In using these equations, the net count is determined
(gross count - background) in each of the selected spectral regions of the
sample spectrum, these values are inserted into the equation, and the true
count due to each nuclide is computed. The counting efficiency factors
are then used to obtain the amount of each radionuclide in the sample.
Inaccuracy may result if a nuclide is present in the sample but is not
accounted for in the set of equations.
A third method, the Least Squares Analysis, necessitates the use of a
computer. This method is described in the course manual Radionuclide
Analysis by Gamma Spectroscepy (Ref. 3).
Alpha Particle Scintillation Counting
Radium-226 is determined at this laboratory by the emanation
technique. The procedure used to prepare and seal the sample is described
in Section C of this manual. After the sealed solution has been stored
for the ingrowth of Rn, the radon is drawn by vacuum and flushed by
nitrogen into a ZnS-lined scintillation cell. The counting system
consists of a photomultiplier tube (which interfaces the scintillation
cell), an electronic circuit which amplifies and shapes the photo-
multiplier signal, and an electromechanical or electronic sealer.
Since the levels of radium encountered in environmental samples are very
B-02-14
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low, long counting times are necessary, on the order of 1000 minutes per
sample.
The efficiency and background of each chamber is determined before
use with a sample. The efficiency is determined by introducing a known
amount of 222Rn gas into the scintillation cell and counting until a
statistically valid number is obtained. The chamber is then cleaned by
alternately evacuating and purging with nitrogen. When free of all
residual radon, the background of the chamber is determined by a 1000
minutes count.
The repetitive determination of backgrounds and efficiencies serves
as a check on the operation of the system in lieu of the daily performance
tests recommended for the previously described systems.
References
1. Kolde, H. E., Quality Control of Radioactivity Counting Systems,
Public Health Service Publication Ho. 99-RH-15 (August 1965).
2. Kahn, Bernd, et al., Rapid Methods for Estimating Fission Product
Concentrations in Milk, U. S. Department of Health, Education, and
Welfare, Public Health Service Publication No. 99-R-2 p. 17, (1963).
3. Radlonucllde Analysis by Gamma Spectroscopy. Training Branch Division
of Radiological Health, U. S. Department of Health, Education, and
Welfare, Public Health Service.
4. Porter, C.R., Augustine, R.J., Matusek, J.H., Jr., and Carter, M.W.,
Procedures for Determination of Stable Elements and Radionuclides in
Environmental Samples. U.S. Department of Health, Education, and
Welfare, Public Health Service Publication Number 999-RH-10 (19G5).
5. Phillips, C.R., Stewart, J.A., and Athey, T.W. Ill, A Computer Program
for the Analysis of Gamma-Ray Spectra by the Method of Least Squares,
U.S. Department of Health, Education, and Welfare, Public Health
Service Publication Number 999-RH-21 (1966).
B-02-15
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TABLE 1
Beta Particle Counting Sample Types and Counting Times
Sample Type
Yttrium oxalate
on 2.5-cm diam-
eter filter
(milk, water, food)
Nuclide
90Y
co^"9
50 min Place filter in center of
5 cm planchet. Count as
soon as possible to reduce
correction for 90y decay.
Strontium oxalate
(total strontium)
on 2.5-cm
diameter filter
(milk, water
food, biota,
silt and soil
Gross beta (5 cm)
on planchet
(vyater, food,
biota, silt, and
soi 1)
50 min
and
90Sr
Gross
beta
20-50
min,
depend-
ing on
count
rate of
sample
Place filter in center of
5 cm planchet. Count as
soon as possible to reduce
correction for 90y ingrowth
and 89$r decay. Count again
after 6-7 days to determine
90$r by differences.
Handle samples carefully to
avoid spilling contents.
B-02-16
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TABLE 2
Alpha Particle Counting Sample Types and Counting Times
Sample Type Huclide Remarks
Gross alpha f5-cm) Gross 25-100 Handle planchet carefully
on planchet alpha nrin to avoid spilling contents.
{water, food,
biota, silt,
and soil)
Total radium- Total 100 mi n Place filter in center of
barium chronate radium 5 cm planchet. Count as
on 2.5-cm soon as possible to avoid
diameter filter correction for radium
(water, food, daughter ingrowth.
biota, silt,
and soil)
B-02-17
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TABLE 3
Hud ides Useful for Calibrating Spectrometer
lluclide
57CO
144Ce
l«Ce
133Ba
13l!
140Ba-140La
103Ru_103Rh
106Ru_106Rh
137Cs
22Na
54Mn
65Zn
60Co
40K
Half-life*
270 d
285 d
32.5 d
10.5 y
8.04 d
12.80 d
39.35 d
368 d
30.17 y
2.60 y
313 d
244 d
5.27 y
1.277 x 109
Energy of principal
gamma rays (MeV)
0.123
0.134
0.142
0.360
0.364
0.637
0.487
0.537
1.596
0.498
0.513
0.662
0.510
1.277
0.840
1.119
1.173
1.46
Channel Mo.
10 keV/Channel
12.",
13.4
14.2
36.0
36.4
63.7
48.7
53.7
159.6
49.8
51.3
66.2
51.0
127.7
84.0
111.0
117.3
146.0
* Half-life of parent nuclide.
B-02-18
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TABLE 4
Typical Efficiencies for a 10cm x 10cm Nal (Tl) Crystal
Radionuclide
l^Ce
131 j
106Ru
137Cs
95Zr_95Nb
54Mn
65Zn
60Co
40K
140Ba
140ga_140|_a
226Ra.214Bi
Energy
Band
MeV
0.09 -
0.33 -
0.47 -
0.62 -
0.71 -
0.80 -
1.06 -
1.27 -
1.40 -
0.45 -
1.53 -
1.69 -
0.13
0.39
0.55
0.70
0.79
0.88
1.18
1.39
1.52
0.53
1.67
1.83
Photopeak
Energy
MeV
.134
.366
.511
.662
.76
.84
1.11
1.332
1.46
0.49
1.60
1.76
3.5-1
0.012
0.048
0.0097
0.034
0.034
0.035
0.015
0.022
0.0023
0.036
0.020
0.0048
1.0-1
0.121
0.080
0.016
0.057
0.050
0.058
0.027
0.036
0.0038
0.058
0.032
0.0090
*Cottage
Cheese
Container
0.018
0.060
0.012
0.038
0.036
0.042
0.017
0.027
0.029
—
0.025
0.0068
* A round, plastic (four inch diameter) container having a 450 ml
capacity.
NOTE: The efficiency is defined for preselected channels spanning
the photopeak and is determined by the equation E = net cpm
dpm in the standard
B-02-19
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PREPARATION OF STANDARDS FOR INSTRUMENT CALIBRATION
Preparation of Strontlum-90 and Yttr1um-90 Secondary Standards
Principle
qn on
In most procedures for determining wSr and 3UY, yttrium 1s
determined as the oxalate, and strontium either as the oxalate or
9ft 90
carbonate. A known quantity of a Sr- Y primary standard Is mfxed
with a predetermined amount of stable strontium and yttrium carrier, and a
radiochemical separation is made. Strontium can also be precipitated as
nitrate in concentrated nitric acid solution, and yttrium can be
precipitated as the hydroxide.
The preparation of pure standards of .Sr and Y fs of prime
concern rather than a quantitative recovery; however, the yield has been
generally over 95 percent. Since these standards are used for procedures
which require the addition of carriers, self-absorption curves are
prepared.
The amounts of strontium and yttrium carrier used in the accompanying
procedures are approximately 10 mg each of yttrium and strontium. Slight
changes in the amount of carrier would not change the results. Much
larger amounts of carrier have been used successfully with the necessary
procedural modification related to self-absorption.
Since the principal product in nitrate separation is strontium. It is
used to prepare the radiostrontlum standard. The principal product in the
hydroxide separation is yttrium, and this Is used to prepare the
radioyttrlum standard. Both procedures, however, are suitable for
preparing both strontium and yttrium standards.
In the nitrate procedure, strontium is separated from yttrium by
precipitation In a concentrated nitric add solution. This 1s a
separation method which has been used frequently in the past. Both
strontium and yttrium nitrate carriers are used and the separation process
is repeated several times to assure purity of precipitate. Although the
B-03-1
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quantitative recovery of strontium Is of secondary Importance, a high
recovery is desirable. Strontium nitrate 1s Insoluble in a 70 percent
nitric acid solution. A 90 percent nitric acid solution permits the
addition of up to 10 ml of water and, therefore, the use of carrier and
standard radlostrontium solutions without the need of evaporation. Fresh
nitric acid should be used. Older nitric acid solutions tend to
decompose, losing some of the nitric acid content, and thus reduce
recovery. The purity of strontium standard is checked by following the
90 90
same nitrate precipitation procedure and replacing uSr- Y with
90 90 90
approximately 10 nanocuries of Y separated from a Sr- Y
solution. Since no radlostrontium is present, any radioactivity in the
strontium precipitate would indicate an impure standard.
The same technique is used to determine the purity of yttrium
am
85
90 90
standard by replacing Sr- Y with approximately 10 nanocuries of
Sr.
The hydroxide separation of strontium and yttrium is carried out
employing the difference in the solubilities of their hydroxides. Both
strontium and yttrium carriers are added and yttrium hydroxide is
precipitated with ammonium hydroxide and purified by multiple reprecip-
itations. The recovery is over 95 percent.
The determination of purity in this procedure is the same as
described in the nitrate separation. In both cases the impurity is less
than 0.1 percent.
The precipitation of yttrium and strontium as oxalates as well as the
strontium carbonate precipitation are established procedures. Strontium
is precipitated as oxalate or carbonate in an ammoniacal solution by the
addition of ammonium oxalate or sodium carbonate.
The precipitation, in most cases, is reasonably complete within a few
minutes, if it is cooled in an ice bath. Strontium oxalate precipitates
as SrCJD-.HgO. Yttrium is precipitated as oxalate in an oxalic
acid medium. As in the case of strontium oxalate, the precipitation is
complete in a few minutes, if cooled in ?n ice bath. Yttrium oxalate
precipitates as Y2(C204)3 • 9HgO.
B-03-2
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Special Apparatus
1. Metricel DM 800 membrane filters or equivalent, 25mm diameter, 0.8
micrometer pore size. See Note 1.
2. Suction filter apparatus.
3. Centrifuge, bench model.
Reagents
1. Ammonium hydroxide, 15M. Reagent grade NH.OH.
2. Ammonium oxalate, saturated solution. Dissolve 142 g of ammonium
oxalate crystals in 500 ml of hot distilled water and dilute to 1
liter with distilled water.
3. Ethanol, 95 percent reagent.
4. Nitric acid, fuming 90 percent.
5. Nitric acid, 16M, 70 percent reagent.
6. Nitric acid, 2M. Dilute 125 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
7. Oxalic acid, 1M. Dissolve 126 grams of crystalline oxalic acid
reagent in 700 ml distilled water and dilute to 1 liter.
8. Sodium carbonate, 1.5J1. Dissolve 159 g of Na2C03 in 900 ml
distilled water and dilute to 1 liter.
9. Strontium carrier, 10 mg Sr+2/ml. Dissolve 24.2 g Sr(N03)2 in
900 ml distilled water. Add 1 ml 16M HN03 and dilute to 1 liter.
10. Yttrium carrier, 10 mg Y+3/ml. Heat (avoid boiling) 12.7 g of
Y203 in 50 ml of 16M HN03 until dissolved. Transfer to a 1
liter volumetric flask and dilute to 900 ml. Adjust to pH2 with 15M
NH4OH and dilute to 1 liter with distilled water.
Procedure - Nitrate Separation
Strontium-90 Oxalate or Carbonate
—~^-^—^——^———^~^ +2
1. Pipette 1 ml of strontium carrier (approximately 10 mg Sr /ml)
and 1 ml of yttrium carrier (approximately 10 mg Y /ml) Into a
centrifuge tube. Add 1 ml of Sr- Y standard activity and
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dilute to approximately 10 nl with distilled water.
2. Add 30 ml of fuming nitric acid. Cool with stirring in ice bath
for 10-20 minutes, centrifuge, and decant the supernate
containing yttrium into a beaker. Record the time as the start
of decay of yttrium.
3. Wash precipitate from step 2 with 3 ml of fuming nitric acid;
centrifuge, decant, and discard the supernate.
3a. For strontium carbonate precipitate, wash precipitate from step 3
with 3 ml of fuming nitric acid, centrifuge, decant, and discard
the supernate.
3b. Dissolve the precipitate in 10 ml of distilled water and add 3 ml
of 15M ammonium hydroxide.
3c. Heat to near boiling in hot water bath and add 5 ml of l.SM^
sodium carbonate and cool in ice bath. Go to step 6 after
precipitating strontium carbonate.
4. For strontium oxalate precipitate, proceed from step 3b to step 5.
5. Heat to near boiling on hot water bath, add 5 ml of ammonium
oxalate, and cool in ice bath.
6. Centrifuge, discard supernate.
7. Transfer strontium carbonate or oxalate precipitate
quantitatively onto a pre-weighed membrane filter with three
10 ml portions of water and wash with three 10 ml portions of
cold alcohol.
8. Carefully mount the filter in a 5 cm planchet, weigh, and count
the strontium-90 activity.
9. Mount filter carefully in a 5 cm planchet and count.
Yttrium-90 Oxalate
10. Evaporate the supernate from step 2 almost to dryness.
11. Transfer the contents of the beaker quantitatively into a
centrifuge tube with four 10 ml portions distilled water.
12. Add 5 ml of 15f1 ammonium hydroxide, stir, centrifuge, and discard
supernate.
B-03-4
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13. Dissolve the precipitate 1n 20 ml of 2M HN03-
14. Repeat steps 12 and 13.
15. Follow steps 5-9 of the Hydroxide Separation.
Procedure - Hydroxide Separation
Yttrium-90 Oxalate
1. Transfer 1 ml of yttrium carrier into a centrifuge tube and add 1
ml of strontium carrier.
2. Add 1 ml of ^Sr-^Y standard activity and dilute to
approximately 20 ml with distilled water.
3. Add 5 ml of 15M ammonium hydroxide, stir, and centrifuge the
yttrium hydroxide. Transfer the supernate Into a 100 ml beaker
to be used for strontium precipitate. Record the time as:the
start of decay of yttrium.
4. Dissolve the precipitate from step 3 in 20 ml of 2M HN03.
5. Add 5 ml of ammonium hydroxide, stir, and centrifuge the
precipitate. Discard the supernate.
6. Repeat steps 4, 5, and 4 again.
7. To precipitate yttrium oxalate, add 5 ml of 1M oxalic acid and
adjust to pH 1.5 with a pH meter, using approximately 2 ml of
15M NH4OH. Stir and cool in an ice bath 10-20 minutes.
Centrifuge and discard the supernate.
Strontlnm-90 Oxalate or Carbonate
8. Transfer the precipitate quantitatively onto a membrane filter
with three 10 ml portions of cold water. Mash with three 10 ml
portions of cold alcohol, dry, and weigh.
9. Mount filter carefully In a 5 cm planenet and count.
10. Evaporate the supernate of step 3 almost to dryness.
11. Transfer the contents of the beaker quantitatively with two 5 ml
portions of distilled water and three 10 ml portions of fuming
nitric acid into a centrifuge tube.
B-03-5
-------
12. Cool in ice bath for 10-20 minutes, centrifuge, and discard the
supernate.
13. Follow the nitrate separation procedure for strontium oxalate or
carbonate precipitation procedure starting at step 3.
Yttrium-90 Efficiency Calculation
The recovery of yttrium is calculated by comparing the weight of
yttrium carrier precipitated as yttrium oxalate and the weight of the
sample.
The efficiency is calculated by means of
E c
(A){R)(D) '
where
E = counting efficiency of yttrium cpm/dpm,
T 1/2 = the half-life of yttrium-90 (64.2 hours),
t = time lapse from precipitation to counting (hours),
C = net counts per minute,
A = original activity in dpm,
R = radiochemical yield express as recovery of yttrium, and
D = the decay calculated from D = e - .693 t .
T 1/2
Sample Calculation
Sampl e
Number
1
2
E = 251 = 0.52
(0.96) (507) (0.976)
E = 249 = 0.53
(0.95) (507) (0.973)
B-03-6
C
251
249
A
507
510
R
0.96
0.95
_t
2.25
2.50
D
0.976
0.973
-------
Strontium-90 Efficiency Calculation
The recovery of strontium 1s determined by comparing weight of
strontium carrier and that of precipitate on the filter.
Calculate the stront1um-90 efficiency using the following equation:
Efficiency = A-[(B)(C)(D)(E)] = A - (D)(E)
(B)(C) (B)(C)
where
A = net counts per minute,
B = original activity in dpm,
C = radiochemical yield expressed as recovery of strontium
carrier,
D = the efficiency of the counter for 90Y,
E = ingrowth of 90Y calculated from 1 - e '-^H- * .
t = time from Y separation to counting (hours), artd
T = the half-life of yttrium.
Sample Calculation
Sample
Number
1
2
E,
A
267.7
272.3
B
800
800
267.7
C
0.98
0.97
(0.52)
t
12
12
(0.122) =
E
0.122
0.122
0.28
D
0.52
0.52
(0.98) (800)
272.3
(.97) (800)
ESr = 272.3 - (0.52) (0.122) = 0.29
B-03-7
-------
Preparation of Gross Beta Standards
Principle
Gross beta determinations sacrifice accuracy for simplicity, and the
selection of a reference radlonuclide determines to a great extent the
reliability of the obtained data. Self-absorption and counting efficiency
depend upon a number of parameters, among them chemical composition of the
compound and the radionuclldes present.
The following materials were used to Investigate of the use of proper
reference radionuclldes for the gross beta determination In food and soil
ash:
(1) Food ash prepared from a mixture of several types of food
representing a total diet of an average U.S. consumer.
(2) Soil from the eastern part of the United States. The soil was ashed
to oxidize any organic compounds which may have been present.
(3) Vegetation ash.
(4) M1lk ash.
(5) Wheat grain cereal ash.
(6) Residue of the evaporation of ocean water.
The selection of a reference radlonucllde for gross beta
determination Is Important. The aim of this Investigation was to select a
reference radlonucllde which most nearly resembles the activity of the
particular natural sample. The most accurate method would have been a
radiochemical separation of all possible and conceivable radionuclldes 1n
the samples. However, this was too elaborate for the scope of this
Investigation. A simpler method with similar results Is the comparison of
the self-absorption of the sample with the self-absorption of the sample
contaminated with the suspected radlonuclide. The latter method has the
advantage that it can be carried out in small laboratories with little
radiochemical capability. Increasing amounts of the ashed sample are
placed on a planchet and counted. The most likely radlonuclide is then
added to the ash and the procedure repeated.
B-03-8
-------
It has been established that in times when no fresh fission products
are 1n the atmosphere the major beta emitters detectable by gross activity
determinations 1n the environmental samples are Sr and K.
Since carrier-free 40K is not available, its substitution by
40
natural potassium represents some uncertainties. The abundance of K
in natural potassium is only 0.10 percent. This necessitates the addition
of a large amount of carrier potassium and an anion such as chloride. The
results of the experiments described in this report indicate, however,
that in some cases the use of potassium as the reference radlonuclide is
justified. Potassium is readily available and the small abundance of
40
K makes weighing errors less probable.
The similarity between the average energy of K and Sr- Y
and their self-absorption curves up to a relatively long range permits
90 90
the use of Sr- Y for the calibration of counting Instruments 1n
low absorption regions (1 mg/cm ) for °K with little error. Only
higher carrier content would result 1n erroneous results.
At low carrier weights for different environmental samples, errors
2
arising from the usage of any ash for weights not exceeding 1 mg/cm are
small. Silica gel has been used for these low weights as It is easy to
handle and readily available. The best results were obtained using a
compound with a mesh size above 325 (10 - 50 micron diameter). It
contained no detectable activity and retained a constant weight over the
required time. Silica gel may also be used as a substitute for ashed
samples, when large quantities of ash are not available.
For the gross beta determination of food and vegetation, the
procedure described for K should be used as the reference method.
90
For gross beta determinations of soil, Sr (in equilibrium with Its
90
daughter product Y) is the preferred radionculide. It should be noted
that these conclusions do not necessarily apply to materials other than
soil, food, vegetation and biota. Different contaminants in these
materials, due to different sampling procedures and/or geographical
origin, may require a different reference method.
B-03-9
-------
Reagents
Potassium chloride
Silica gel (10-50 micron diameter mesh)
Strontium-90 standard
Ethanol (95 percent)
Procedure
Self-absorption curve of natural activity of ashed samples
1. Prepare duplicate samples on 5 cm planchet with the following
approximate mg weights of ash or silica gel: 20, 40, 80, 120,
160, 200, 300, 400, 600, 1000, 3000, 5000.
2. Add 5-10 ml etnano! to each planchet.
3. Evaporate gently to dryness. (If an even distribution is not
achieved the first time, add 5-10 ml of ethanol and evaporate
gently to dryness).
4. Weigh the content of the planchet accurately (it should be
kept in a desiccator).
5. Count.
Self-absorption curve of Potassium-40
Place 10 g of potassium chloride in a beaker and dissolve it in
50 ml of water. Add 50g of ash and stir thoroughly with a glass rod.
Evaporate to dryness and follow the above procedure for natural activity
(steps 1-5) by weighing aliquots of the dried material on planchets.
Self-absorption curve of Strontium-90 - Yttrium-90
Place 50 g of ash in a beaker, add 100 ml of ethanol and 1 ml of
90
Sr standard (2,000 dpm). Stir thoroughly with a glass rod and
evaporate to dryness. Follow the preceding procedure for natural activity
(steps 1-5).
B-03-10
-------
Calculations
Since the natural activity of a sample is usually unknown, the
self-absorption curve is prepared by calculating the cpm/mg of each
2 2
planchet and plotting this against mg/cm . Extrapolate mg/cnr to zero
and use this value as cpm/mg with no self-absorption. Counting Tosses at
the various weights can be calculated and a subsequent curve can be drawn
2
plotting percent loss versus mg/cm .
This curve is then used in the following equation relating measured
counts to sample activity:
pCi/g ,
(2.22)(B)(C){D)
where
A = net cpm,
B = counting efficiency in terms of cpm/dpm,
C = weight of sample in grams,
D = transmittance, as 1 - self-absorption, and
2.22 = dpm/pCi.
Preparation of Gross Alpha Standards
Most of the comments made for gross beta determination apply to the
gross alpha activity determination. An additional complication is the
short range of alpha particles and the varied energies of natural
radioactivity.
239
For the preparation of the self-absorption curve, Pu was
selected as the reference radionuclide. Advantages of this radtonuclide
are (1) its energy of 5 MeV is an average between the naturally occurring
alpha emitters, {2} the long half-life of the daughter product U
delays its production even in several years, and (3) plutonium has no beta
and only small gamma emission.
B-03-11
-------
The procedure for preparing standards for self-absorption curves is
identical to that of 90Sr-90Y, replacing 90Sr by 239Pu.
Calculations
The gross alpha self-absorption curve is prepared exactly the same as
that for gross beta. However, due to the short range of alpha particles,
the infinite thickness is readily obtained and the specific activity is
easily determined. It is not necessary to go beyond 2000 mg in weight.
Calculate the gross alpha activity from the following equation:
gross alpha, pCi/g = A ,
(2.22)(B)(C)(D)
where
A = net cpm,
B = counting efficiency in terms of cpm/dpm,
C = weight of sample in grams,
D = transmittance, 1 - self-absorption, and
2.22 = dpm/pCi.
For an infinitely thick sample, (2.22)(B)(C)(0) is a constant and
this calculation is reduced to pCi/g = A K, where K = 1
(2.22)(B)(C)(D)
Motes
1. Metricel is a trademark of Gelman Sciences, Inc., Ann Arbor, Michigan.
References
1. Porter, C.R., Augustine, R.J., Matusek, J.M., Jr., and Carter, M.W.,
Procedures for Determination of Stable Elements and Radionuclides in
Environmental Samples, U.S. Department of Health, Education, and
Welfare, Public Health Service Publication Number 999-RH-10 (1965).
B-03-12
-------
RADIOCHEMICAL DETERMINATION OF AMERICIUM-241 IN ASHED SAMPLES
(Including Soil, Fly Ash, Ores, Vegetation and Biota)
Principle
The sample is ashed at 550°C for 72 hours. Americium-243 tracer is
added to a weighed aliquot of sample. The sample is then solubillzed with
a mixture of HF and HC104. Plutonium and uranium are removed by
extraction into triisooctylamine (TIOA). Thorium Is removed by adsorption
on anion exchange resin. Americium Is extracted from nitric acid into
dibutyl-N, N-diethyl carbamyl phosphonate (DOCP). The americium Is
stripped from DDCP with dilute nitric acid and coprecipltated with 0.1 mg
lanthanum as fluoride. The actinide 1s radioassayed by alpha spectroscopy.
Special Apparatus
1. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore size
or equivalent. See Note 1.
2. Suction filter for 25 mm membrane.
3. Plastic graduated cylinder, 100 ml volume.
4. Separator/ funnels, 1 liter capacity.
5. Planchets, stainless steel, 32 mm diameter.
6. Alpha spectrometric system consisting of multichannel analyzer
biasing electronics, printer, silicon surface barrier detectors,
vacuum pump and chamber.
7. Teflon beakers. See Note 2.
8. Ion exchange column, 2 cm diameter, 10.5 cm length.
Reagents
1. Americium-243 tracer solution. Approximately 1 pCi per ml,
calibrated.
2. Anion exchange resin. BioRad AG1X8 or equivalent (200-400 mesh,
nitrate form). Convert to nitrate form for thorium separation by
AM-01-1
-------
washing the resin with 6f1 HN03 until the washing shows no trace
of chloride when tested with AgMO-j. See Note 3.
3. Dibutyl-N, M-diethyl carbarnyl phosphonate (DDCP). See Note 4.
4. Hydrochloric acid, 131, 37 percent HC1 reagent.
5. Hydrochloric acid, 9^. Dilute 750 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
6. Hydrochloric acid, 1M. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
7. Hydrofluoric acid, 29M, 48 percent HF reagent.
8. Hydrofluoric acid, 3*1. Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic graduate
and storage bottle.
9. Hydrogen peroxide, 50 percent reagent grade.
10. Lanthanum carrier, O.lmg La per ml. Dissolve 0.0799g
11. La(M03)3» 6H20 per 250 ml 1M HC1.
12. Mi trie acid, 16M, 70 percent HN03 reagent.
13. Nitric acid, 1214. Dilute 750 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
14. Nitric acid, 6M. Dilute 375 ml of the 70 percent reagent grade
HH03 to 1 liter with distilled water.
15. Nitric acid, 2M. Dilute 167 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
16. Perchloric acid, 12M, 70 percent HCIO^ reagent.
17. Silver nitrate, crystalline reagent.
18. Silver nitrate, 0.1M. Dissolve 1.7 g AgN03 reagent in
distilled water. Add 1 ml 6M HN03 and dilute to 100 ml with
distilled water.
19. Triisooctylamine (TIOA), reagent grade.
20. TIOA solution in p-xylene, 10 percent. Dissolve 100 ml
triisooctylamine in p-xylene and dilute to 1 liter with p-xylene.
21. p-Xylene, reagent grade.
AM-01-2
-------
Sample Preparation
1. Add weighed 1 gram aliquot of ashed sample to Teflon beaker.
2. Add measured aliquot of americium-243 tracer solution.
3. Add 15 ml of 29M HF and evaporate to dryness. Repeat this step
two more times to volatilize silica as S1F4>
4. Add 5 ml of 12M HC104 and 5 ml of 9M HC1. Evaporate to dryness
and repeat tbis step.
5. Add 10 ml 12M HC1 and dissolve residue.
6. Transfer sample to 400 ml glass beaker, washing Teflon beaker
with 9M HC1.
7. Evaporate solution in glass beaker to dryness. Add 10 ml 12M^ HC1
and repeat this step. Avoid baking solids.
Determination
1. Dissolve sample by adding 100 ml 9M HC1 and warming beaker to
maximum of 50°C.
2. Add 2 ml 50 percent H202. Heat gently and set aside for 10
minutes.
3. Place 100 ml 10 percent TIOA in 500 ml separatory funnel. Add 50
ml 9M HC1 and shake for one minute to equilibrate. Allow phases
to separate cleanly and draw off and discard lower aqueous acid
phase.
4. Add sample to TIOA in separatory funnel and shake for two
minutes. Vent funnel stopcock frequently to avoid pressure
build-up in funnel.
5. Allow phases to separate cleanly. Draw off and save aqueous acid
phase.
6. Add 50 ml 9M HC1 to TIOA solution to separatory funnel and shake
for 1 minute.
7. Allow phases to separate and drain 9M HC1 wash into beaker
containing acid from step 5.
8. Repeat steps 6 and 7.
AM-01-3
-------
9. Put combined acid phases In clean 500 ml separatory funnel and
add 100 ml p-xylene to funnel. Shake for one minute.
10. Allow phases to separate cleanly and drain off aqueous acid phase
Into clean beaker.
11. Add 10 ml 101 HN03 and 5 ml 12M HC104 to aqueous acfd phase
and evaporate to near dryness. Do not overheat solids.
12. Add 10 ml 16M HN03 and evaporate to near dryness.
13. Dissolve sample in 50 ml of 6N HNOj with warming.
14. Prepare ion exchange column with 25 ml of anion exchange resin.
Wash resin with 100 ml of 6M HN03.
15. Place sample in 125 ml separatory funnel on top of column acting
as reservoir.
16. Allow sample to flow through column at the rate of approximately
2 ml per minute. Collect eluate and do not allow column to run
dry.
17. Flow 100 ml 614 HN03 through column after sample has passed
through. Collect in same beaker as sample.
18. Evaporate eluate just to dryness and allow beaker containing
residue to cool.
19. Add 20 ml distilled water to residue and swirl to dissolve
residue. The solution may not appear completely clear at this
step.
20. Add 10 ml of 16M HN03 to the solution and heat to near boiling.
21. Remove the solution from the hot plate and add 10 ml of 16M
HN03.
22. Pour the solution into a 125 ml separatory funnel and rinse the
beaker with two 10 ml volumes of 16M HN03. Transfer rinses to
funnel.
23. Allow the solution to cool to ambient temperature and add 1 ml of
DDCP.
24. Shake the separatory funnel vigorously for 15 seconds.
AM-01-4
-------
25. Allow the layers to separate for at least 2 hours or overnight if
possible.
26. Drain and discard the aqueous (lower) layer.
27. Add 10 ml of 12M HN03 into the funnel and shake for 5 seconds.
28. Allow 1 hour for the layers to separate, drain and discard the
lower rinse solution. See Note 5.
29. Add 10 ml p-xylene to the DDCP in the separator? funnel.
30. Add 20 ml of 2M HN03 to the funnel and shake vigorously for 15
seconds.
31. Allow the layers to separate for at least 30 minutes and drain
strip solution into a 100 ml beaker.
32. Repeat step 30 and combine second strip solution with first.
33. Place combined 2M HN03 strip solution in clean 125 ml
separatory funnel.
34. Add 25 ml p-xylene to funnel and shake for 15 seconds.
35. Allow phases to separate and drain lower layer into clean 100 ml
beaker.
36. Evaporate strip solution just to dry ness.
37. Add 10 ml 16M HN03 and 5 ml 12M HC104 to beaker and evaporate
to dry ness.
38. Add 10 ml 12M HC1 and evaporate to near dryness.
39. Take up residue 1n 50 ml 1M HC1.
40. Heat on water bath to 80°C with stirring.
41. Suspend clean nickel foil strip into solution for two hours to
remove traces of polonium.
42. Remove nickel strip and evaporate solution to dryness.
43. Add 15 ml 1M_ HC1 to beaker and warm to dissolve residue.
44. Coprecipitate amertclum fluoride by adding 1 ml of lanthanum
carrier and 5 ml 314 HF. Mix well and set aside for 30 minutes.
45. Filter coprecipitated sample through a filter membrane with
suction.
46. Rinse sample beaker with water and add to filter funnel.
AM-01-5
-------
47. Rinse beaker with alcohol and add to funnel. Mash funnel with
alcohol.
48. Disassemble filter funnel when membrane Is dry. Mount membrane
on a 32 mm planehet using double stick tape.
49. Radloassay sample for amerfclum-241 In alpha spectrometer.
Calculations
Calculate the concentration, Z, of amerlclum-241 In picocuries per
gram as follows:
z = (A-AL)(F)
(2.22)(B-Bi)(E)(H)(T)
where
A = gross sample counts which appear In the americiuin-241 alpha
energy region,
A. = background counts in the same alpha energy region as A above,
F = total calibrated tracer counts for same counting time as
sample counts,
2.22 = dpm per pCi,
B » gross tracer counts which appear in the alpha energy region
of the tracer Isotope,
B. = background counts 1n the same alpha energy region as £ above,
E = alpha detector efficiency,
U = sample weight (grams), and
T = counting time (minutes).
Calculate the lower limit of detection (LLD) In picocuries per gram
as follows:
LID- *-66V CBT
(2.22)(E)(R)(W)(T)
AM-01-6
-------
where
Cg = background count rate,
T = counting time,
2.22 = dptn per pCi,
E = alpha detector efficiency,
R = fractional yield based on B-Bj/F in calculation, and
W = sample weight (grams).
This LLD calculation is valid if the sample counting time is equal to
the background counting time.
Notes
1. Nuclepore is a registered trademark of Nuclepore Corp., Pleasanton, CA.
2. Teflon is a registered trademark of DuPont Co., Wilmington, DE.
3. Thorium in the sample may be determined by washing the resin with
water and measuring the thorium in the wash.
4. DDCP is currently available from Columbia Organic Chemical Company,
Columbia, SC.
5. When draining the separatory funnel always allow a small quantity of
aqueous phase to remain in funnel. Avoid letting organic phase into
stopcock.
6. If plutonium analysis is attempted sequentially with americium, the
plutonium-242 tracer should be checked for plutonium-241 content.
This isotope decays to americium-241.
References
1. Moore, F. L., "Liquid-Liquid Extraction of Uranium and Plutonium from
Hydrochloric Acid Solution with Tri (iso-octyl) amine," Analytical
Chemistry 30, 908 (1958).
2. Butler, F. E., "Determination of Actinides in Biological Samples with
Bidenate Organophosphorus Extractant," Analytical Chemistry 42, 1073
(1970).
AM-01-7
-------
RADIOCHEMICAL DETERMINATION OF CARBON-14 IN AQUEOUS SAMPLES
Principle
Carbon carrier In the form of sodium oxalate Is added to an
unacidified aqueous sample in a closed distillation apparatus. An
oxidizing agent and acid are added to the sample to convert carbon
compounds to C02. Nitrogen is slowly bubbled through the sample and
heat is applied to transfer the C02 into a flask containing a basic
CaCl2 solution. The collected CaC03 is centrifuged, washed,
transferred to a planenet, weighed, and counted.
Special Apparatus
1. Low background beta particle counter with a window less, than
2 mg/cm thickness.
2. Centri fuge.
3. Stainless steel planchets, 5 cm diameter.
4. Infrared heat lamp.
5. Distillation apparatus (see Figure 1).
Reagents
1. Ammonium hydroxide, 15 n. NH^OH reagent.
2. Ammonium hydroxide, 0.1 H. Dilute 6.7 ml of the NH^OH reagent
to 1 liter with distilled water.
3. Calcium chloride, crystalline reagent.
4. Calcium chloride, 1.5 H. Dissolve 166.5 g CaCl2 reagent in 700
ml distilled water and dilute to 1 liter with distilled water.
5. Potassium permanganate, crystalline reagent.
6. Potassium permanganate, 0.5 M. Dissolve 79.0 g KMn04 reagent
in 700 ml distilled water and dilute to 1 liter with distilled
water.
7. Sodium oxalate, crystalline reagent.
8. Sodium oxalate carrier, 0.1 M. Dissolve 13.4 g NaC0
C-01-1
-------
reagent In dfstflled water and dilute to 1 liter with distilled
water. See Note 1.
9. Sulfurlc acid, 18 fl. 96 percent H2S04 reagent.
10. Sulfurlc acid, 9 M. Dilute 500 ml H2S04 to 1 liter with
distilled water.
Procedure
1. Add 1 ml Na2C204 solution to a 200 nil neutral or basic
sample 1n a distillation flask.
2. Start a slow bubbling of nitrogen or COg-free air through the
solution and connect the distilling outlet to a 200 ml receiving
• flask containing 100 ml 0.1 M NH4OH and 1 ml 1.5 ^ CaClg.
3. With the system closed, add 1 ml 0.5 M KMn04 and 5 ml 9 M
HgS04 through the separator/ funnel to the distilling flask
and swirl to mix contents.
4. Heat flask and boil contents gently for 30 minutes while bubbling
the N2 (or air) through the distilling and receiving flasks.
5. Transfer the precipitated CaC03 from the receiving flask to a
centrifuge tube. Centrifuge and discard supernatant solution.
6. Wash precipitate twice with 15 ml aliquots of boiled distilled
water and discard wash solutions.
7. Take up precipitate in 5 ml boiled distilled water and transfer
quantitatively to a weighed stainless steel planchet.
8. Dry precipitate under a heat lamp, cool, and weigh. Compute
chemical yield based on the total weight of CaC03 formed.
9. Count with a thin window beta particle counter (< 2 mg/cm ).
Calculation
Calculate the concentration, Z, of carbon-14 in picocurfes per
milliliter as follows:
7 = cl ' CB
(2.22)(EMV)(R)
C-01-2
-------
where
C. = gross count/minute of sample,
CB = background counts/minute,
E = beta particle counter efficiency,
V = sample volume (ml),
R = fractional chemical yield, and
2.22 = dpm/pCi.
Calculate the lower limit of detection (LLD) for carbon-14 in
picocuries per milliliter as follows:
LLD = 4'66
(2.22)(E)(V)(R)(T)
where
CB = background counts/minute,
E = beta particle counter efficiency,
V = sample volume (ml),
R = fractional chemical yield,
T = counting time, and
2.22 = dpm/pCi.
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. The Na2C204 should be standardized frequently by distillation
with boiled distilled water. One ml of 0.1 M Na2C204 is
equivalent to 20 mg CaC03. The standardized value will include any
C02 absorbed by the carrier solution upon standing.
C-01-3
-------
References
1. Krieger, H.L., and Gold, S., Procedure for Radlochemical Analysis of
Nuclear Reactor Aqueous Solutions, EPA-R4-73-014, May 1973.
C-01-4
-------
Dropping
Funnel
Vent
Basic CaCI2
Sample
Figure 1. Carbon-14 distillation apparatus.
C-01-5
-------
RADIXHEMICAL DETERMINATION OF TRITIUM IN MILK. SOIL. URINE.
VEGETATION AMD OTHER BIOLOGICAL SAMPLES
Azeotropic Method
Principle
Tritium activity in the water content of a sample is radioassayed
after separating the water froro the sample by a cyclohexane-water
azeotropic distillation. A measured aliquot of the sample is heated in an
azeotrope still together with cyclohexane. The separated water is
measured and counted for tritiun using a liquid scintillation spectrometer.
Special Apparatus
1. Azeotropic still. See Figure 1.
2. Liquid scintillation counter, ambient temperature operation. See
Mote 1.
3. Low background counting vials, 25 ml capacity. See Note 2.
Reagents
1. p-Bis (o-methylstyryl) benzene (bis MSB).
2. Cyclohexane, spectrophotometrie grade reagent.
3. Desiccant, calcium chloride type.
4. 2,5-Diphenyloxazole (PRO).
5. Scintillation solution. Dissolve 7.0 g of 2,5-diphenyloxazole
(PRO) and 1.5 g of p-bis (o-methylstyryl) benzene (bis MSB) in 1
liter of p-xylene. Mix this solution with Triton N101 in a
volume ratio of 2.75 parts of p-xylene solution to 1 part of
Triton MIDI. The correct volume of Triton N101 is 364 ml for
each liter of p-xylene. Store the solution in a brown bottle and
protect from sunlight.
6. Tritiated water standard containing nominally 5 X 10 dpm
H/ml known to 3 percent accuracy.
H-01-1
-------
7. Triton N101, Rohm and Haas Co., Philadelphia, PA. See Mote 3.
8. p-Xylene, scintillation grade reagent.
Procedure
1. Add measured sample and cyclohexane to distillation flask using
amounts shown in Table 1.
2. Assemble distillation apparatus and heat sample flask until water
stops collecting in receiver.
3. Stop distillation and measure volume of collected water.
4. Place 10 ml aliquot of collected water in liquid scintillation
vial and add 15 ml scintillation solution.
5. Prepare blank solution with low tritium water using same volume
of water as sample.
6. Prepare standard solution of tritiated water with same volume of
water as sample.
7. Place sample vials in liquid scintillation counter and allow
vials to dark adapt for one hour before starting counting
sequence.
Calculations
Calculate the concentration, Z, of tritium in picocuries per sample
as follows:
Z = Cl ' CB
(2.22HEHV)
where
C. = gross beta counts per minute,
CB = scintillation counter background counts per minute,
E = counting efficiency,
V = sample size, and
2.22 = dpm per pCi.
H-01-2
-------
Calculate the lower limit of detection (LLD) in picocuries per sample
as follows:
/
LLD = ~"vw ^ CBT
(2.22)(E)(T)(V)
where
n
C = background count rate,
T = counting time,
E = counting efficiency,
V = sample size, and.
2.22 - dpm per pCi.
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. For optimum performance of the scintillation solution, the temperature
of the counting instrument should be kept should be between 18 and
25°C.
2. Low potassium glass or plastic vials should be used to minimize
background counts. Plastic vials should be resistant to the
scintillation solution. The solvent, p-xylene, will migrate through
the plastic vials, therefore the samples should be counted no longer
than three days after preparation.
3. Triton N101 is a tradename for a nonylphenol polyethylene glycol ether.
References
1. W. M. Jones, J. Chemical Physics, 48, 207 (1968).
H-01-3
-------
2. 1969 Book of ASTM Standards, Part 18, 2nd ed., American Society for
Testing and Materials, pp. 16-19.
3. R. Lieberman and A. A. Moghissi, Inter. J. Appl. Rad. Isotopes, 21,
319 (1970).
4. A. A. Moghissi, E. W. Bretthauer, and E. H. Compton, Analytical
Chemistry. 45 1965, (1973).
5. A. A. Moghissi, Health Physics, 41, 413, (1981).
H-01-4
-------
TABLE 1
Sample Sizes and the Quantity of Cyclohexane
Required for Various Sample Types
Sample Sample Cyclohexane
Type Size (ml)
Soil 200 g 1300
Hay 50 g 400
Green Chop 30 g 70
Biological Tissue 30 g 150
Urine 20 ml 50
Milk 30 ml 70
H-01-5
-------
DRYING AGENT
COOLING WATER
Figure 1. Azeotrope still.
H-01-6
-------
RADIOCHEMICAL DETERMINATION OF TRITIUM IN WATER
Dioxane Method
Principle
Water samples that have been distilled are incorporated into a
counting mixture consisting of dioxane, naphthalene, and fluors. The
tritium is assayed on a liquid scintillation spectrometer.
Special Apparatus
1. Liquid scintillation counter.
2. Low background counting vials.
3. Sample distillation glassware.
Reagents
1. p-Bis (o-methylstyryl) benzene (bis MSB).
2. p-Dioxane, scintillation grade.
3. 2,5-Diphenyloxazole (PRO).
4. Desiccant, calcium sulfate type.
5. Naphthalene, scintillation grade.
6. Tritiated water standard containing nominally 5 X 10 dpm
H/ml known to 3 percent accuracy.
7. Scintillation solution. Dissolve 7.0 g of 2,5 diphenyloxazole
(PPO), 1.5 g p-bis (o-methylstyryl) benzene (bis MSB) and 120 g
naphthalene in 800 ml p-dioxane and dilute to 1 liter with
p-dioxane. Store the solution in a brown bottle and protect from
sunlight.
Procedure
1. Distill aqueous sample in glass. Collect enough distillate for
at least two determinations.
2. Dispense 16 ml of the above scintillation solution into a
H-02-1
-------
counting vial. Add 4 ml of the distilled aqueous sample, cap
vial and shake to mix contents.
3. Prepare standards and backgrounds identical to the samples using
low tritium water, if available, for preparing background samples.
4. Place sample vials in liquid scintillation counter and allow
vials to dark adapt for one hour before starting counting
sequence.
5. Count samples in duplicate for at least 50 minutes each.
Calculations
Calculate the concentration, Z, of tritium in picocuries per liter as
follows:
Cl " CB
(2.22MEMV)
where
Cj = gross beta counts per minute,
CB = scintillation counter background counts per minute,
E = counting efficiency,
V = volume of water (liters), and
2.22 = dpm per pCi.
Calculate the lower limit of detection (LLD) in picocuries per liter
as follows:
LLD =
4.66VCBT
Y Q
(2.22)(E)(T){V)
where
Cg = background count rate,
H-02-2
-------
T = counting time,
E = counting efficiency,
V = sample size (liters), and
2.22 = dpm per pCi.
This LLD calculation is valid if the sample counting time is same as
the background counting time.
References
1. Butler, F. E., "Determination of Tritium in Water and Urine,"
Analytical Chemistry 33, 409-411, (1961).
H-02-3
-------
RADIOCHEMICAL DETERMINATION OF TRITIUM IN WATER
Emulsion Method
Principle
Water samples that have been distilled are incorporated into a
counting mixture consisting of a primary solvent, emulsifier, and fluors.
The tritium is assayed on a liquid scintillation spectrometer.
Special Apparatus
1. Liquid scintillation counter, ambient temperature operation. See
Note 1.
2. Low background counting vials, 25 ml capacity. See Note 2.
3. Sample distillation glassware.
Reagents
1. p-Bis (o-methylstyryl) benzene (bis MSB).
2. 2, 5 - Diphenyloxazole (PRO).
3. Desiccant, calcium sulfate type,
4. Tritiated water standard containing nominally 5 x 10 dpm
3H/ml known to 3 percent accuracy.
5. Triton N101, Rohm and Haas Co., Philadelphia, PA. See Note 3.
6. p-Xylene, scintillation grade reagent.
7. Scintillation solution. Dissolve 7.0 grams of 2, 5 -
diphenyloxazole (PPO) and 1.5 grams of p-bis (o-methylstyryl)
benzene (bis MSB) in one liter of p-xylene.
Mix the above solution and Triton N101 in a volume ratio of 2.75
parts of p-xylene to 1 part of Triton N101. The correct volume
of Triton N101 is 364 ml for each liter of p-xylene. Store the
solution in a brown bottle and protect from sunlight.
H-03-1
-------
Procedure
1. Distill aqueous sample in glass. Collect enough (>25 ml)
distillate for at least two determinations.
2. Dispense 15 ml of the above scintillation solution into a 25 ml
counting vial. Add 10 ml of the distilled aqueous sample, cap
vial and shake to mix contents. See Note 4.
3. Prepare standards and backgrounds identical to the samples using
low tritium water, if available, for preparing background samples.
4. Place sample vials in liquid scintillation counter and allow
vials to dark adapt for one hour before starting counting
sequence.
5. Count each sample in duplicate for at least 50 minutes each.
Calculations
Calculate the concentration, Z, of tritium in picocuries per liter as
follows:
Z =
(2.22MEMV)
where
Cj = gross beta counts per minute,
CB = scintillation counter background counts per minute,
E = counting efficiency,
V = volume of water (liters), and
2.22 = dpm per pCi.
Calculate the lower limit of detection (LLD) in picocuries per liter
as follows:
LLD =
4.66VCgT
(2.22)(E)(T)(V)
H-03-2
-------
where
Cn = background count rate,
T = counting time,
E = sample size (liters), and
2.22 = .dpm per pCi.
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. For optimum performance of the scintillation solution, the temperature
of the counting instrument should be kept should be between 18 and
25°C.
2. Low potassium glass or plastic vials should be used to minimize
background counts. Plastic vials should be resistant to the
scintillation solution. The solvent, p-xylene, will migrate through
the plastic vials, therefore the samples should be counted no longer
than three days after preparation.
3. Triton MIDI is a brand name for a nonyl phenol polyethylene glycol
ether.
4. Smaller vials can be used, keeping the added aqueous sample at 40
percent of the capacity of the vial, and scintillation solution at 60
percent.
References
1. Lieberman, R. and Moghissi, A. A., "Low-level counting by Liquid
Scintillation, II. Application of Emulsions in Tritium Counting,"
Inter. J. Appl. Rad. Isotopes. 21, 319 (1970).
H-03-3
-------
RADIOCHEHICAL DETERMINATION OF IODINE-131 IN DRINKING MATER
Principle
Stable fodate carrier is added to an acidified sample of drinking
water. After reduction to the iodide state by Ma2S03, the radioiodine
is precipitated as Agl. The precipitate is dissolved and purified by
addition of zinc powder and sulfuric acid. The iodine is reprecipitated
as PdI2 for radioassay.
Special Apparatus
1. Low background beta counter.
2. Centrifuge.
3. Electric hot plate.
4. Suction filter apparatus for 25 mm filter membranes.
5. Metricel DM800 membrane filters, 25mm diameter, 0.8 micrometer
pore size or equivalent. See Note 1.
6. Stainless steel planchets, 5 cm diameter.
7. Glassware
8. Analytical balance.
Reagents
1. Ammonium hydroxide, IBM. Reagent grade NH^OH.
2. Ammonium hydroxide, 6M. Mix 400 ml 15M NH4OH with 600 ml
distilled water.
3. Ethanol, 95 percent reagent.
4. Hydrochloric acid, 12H, 37 percent HC1 reagent.
5. Hydrochloric acid, 6M. Dilute 500 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
6. lodate carrier, 10 mg lO^/ml. Dissolve 12.24 g KI03 in
900 ml distilled water and dilute to 1 liter with distilled
water. See Note 2 for standardization.
7. Nitric acid, 16M, 70 percent HN03 reagent.
1-01-1
-------
8. Nitric acid, 0.4^. Dilute 25 ml reagent grade HN03 to 1 liter
with distilled water.
9. Palladium chloride, 0.2M. Dissolve 3.55g PdClg • 2H20 in 90
ml distilled water and dilute to 100 ml with distilled water.
10. Silver nitrate, 0.1M. Dissolve 16.99g AgN03 in 900 ml
distilled water and dilute to 1 liter with distilled water.
11. Sodium sulfite, 1M. Dissolve 12.6g Na2S03 in 90 ml distilled
water and dilute to 100 ml with distilled water. Prepare fresh
daily.
12. Sulfuric acid, 1M. Dilute 56 ml of the 96 percent reagent grade
H2S04 to 1 liter with distilled water.
13. Zinc, reagent grade powder.
Procedures
1. To a 2 liter drinking water sample add 15 ml 16^ HN03 and 1 ml
iodate carrier and mix well.
2. Add 4 ml freshly prepared 1M Na2S03 and stir for 30 minutes.
3. Add 20 ml 0.1 fl AgN03, stir for one hour and allow precipitate
formed to settle for another hour.
4. Decant as much supernate as possible without losing any
precipitate and discard.
5. Filter the remaining liquid through a filter membrane and discard
filtrate.
6. Transfer the filter membrane and precipitate (Agl) to a
centrifuge tube and slurry with 10 ml water.
7. Add 1 gram zinc powder and 2 ml W H2S04 and stir frequently
for 30 minutes.
8. Filter mixture from step 7 with suction using a filter membrane
and collect filtrate in a centrifuge tube. Use five ml water to
wash residue and filter chimney. Discard residue.
9. Add 2 ml 6M HC1 to filtrate and heat tube containing filtrate in
a water bath at 60°C.
1-01-2
-------
10. Add 1 ml 0.2 M PdClg and digest for at least five minutes while
heating.
11. Centrifuge and discard supernate.
12. Dissolve the precipitate in 5 ml 6M NH4OH and heat in a boiling
water bath until clear.
13. Filter solution from step 12 with suction using a filter membrane
or equivalent. Collect filtrate in a centrifuge tube washing the
residue and filter chimney with 5 ml water. Discard residue.
14. Add 6M HC1 to filtrate from step 13 until color changes to
yellow, using approximately 2 ml 6M HC1. Add an additional 2 ml
6M HC1 and heat to 60°C in a water both.
15. Add 1 ml 0.2M PdCl2 to reprecipitate PdI2 and digest on the
water bath for ten minutes. Cool slightly.
16. Filter through a tared filter membrane transferring precipitate
from tube to filter with water. Wash precipitate with 5 ml
ali quots of water and ethanol.
17. Dry precipitate at 70°C for 30 minutes to constant weight and
weigh to the nearest 0.1 mg.
18. Place filter on planchet and count on a low background beta
counter for 1000 minutes.
Calculations
Calculate the concentration, Z. of iodine-131 in picocuries per liter
as follows:
Z =
(2.22){A)(E)(V)(R)
where
C = net count rate, counts per minute,
A = decay correction for iodine-131 (half-life =8.04 days),
E = counter efficiency,
1-01-3
-------
V = sample volume (liters),
R = fractional chemical yield based on weight of PdI2, and
2.22 = dpm per pCi.
Calculate the lower limit of detection (LLD) in picocuries of
iodine-131 per liter as follows:
LLD = ' CBT
(2.22)(E)(R)(T)(V)
where
CB = background count rate,
E = beta counter efficiency,
R = fractional chemical yield based on weight of PdI2,
T = counting time (same for sample and background),
V = sample size (liters), and
2.22 = dpm per pCi.
This LLD calculation is valid if the sample counting time is
approximately equal to the background counting time.
Notes
1. Metricel is a trademark of Gelman Sciences Inc., Ann Arbor, MI.
2. Standardization of lodate Carrier. Pipette 1.0 ml potassium iodate
(KI03) carrier into a 50 ml centrifuge tube containing 10 ml 0.4^
HN03. Add 1 ml 1M Ma2S03 and stir in a water both for 5
minutes. Add 1 ml 0.2 M PdCl- to precipitate and coagulate Pdl-.
Cool and filter through a tared filter membrane. Dry to constant
weight at 70°C, cool and weigh as PdI2.
1-01-4
-------
References
1. Krieger, Herman L., Prescribed Procedures for Measurement of
Radioactivity in Drinking Water, EPA-600/4-80-032, (1980).
2. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual, 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
New York.
1-01-5
-------
RADIOCHEMICAL DETERMINATION OF IODIHE-131 IN MILK
Principle
The milk is preserved at sampling by adding formalin containing
iodide carrier. The milk sample is stirred with anion exchange resin and
the iodine is eluted from the resin after oxidation to 10^ with
hypochlorite solution. After reduction, the iodine is extracted into
CCl., reduced with bisulfite, and back-extracted into water. The iodine
is then precipitated as Pdlg. Chemical yield based on added iodine
carrier is determined gravimetrically. The iodine-131 is measured by
counting in a low background beta counter.
Special Apparatus
1. Metricel DM 800 filter membranes or equivalent, 25 mm diameter,
0.8 micrometer pore size. See Mote 1.
2. Magnetic stirrer and stirring bars, 6 cm.
3. Stainless steel planchets, 5 cm diameter.
4. Suction filtering apparatus for 25 mm filter membranes.
5. Low background beta counter.
6. Separatory funnel, 500 ml capacity.
7. Glassware.
Reagents
1. Anion exchange resin. Dowex 1X8, 50-100 mesh, or equivalent,
Cl"/forrn. See Note 2.
2. Carbon tetrachloride, reagent grade.
3. Formalin, 37 percent formaldehyde solution, reagent grade.
4. Hydrochloric acid, 12^, 37 percent HC1 reagent.
5. Kydroxylamine hydrochloride, reagent grade crystals.
6. Iodide carrier, 10 mg I~/ml. Dissolve 1.8 g reagent grade Nal
in 100 ml distilled water.
+2
7. Palladium chloride, 10 mg Pd /ml. Dissolve 2.0 g PdCl2 2H,0
in 100 ml distilled water.
1-02-1
-------
8. Sodium bisulfite, 1M. Dissolve 1.04 g of NaHS03 in 10 ml
distilled water. Prepare fresh daily.
9. Sodium chloride, 2M. Dissolve 116.9 g NaCl in 900 ml distilled
water and dilute to 1 liter with distilled water.
10. Sodium hypochlorite, 5 percent (commercial laundry bleach).
Preservation of Milk Sample
Add 80 ml formalin containing 2 ml of iodide carrier to four liters
of milk. Add 5 drops of freshly prepared 1N[ NaHS03 to each four liter
sample.
Procedure
1. Pour a 4 liter milk sample into a 4 liter beaker and add a 50 ml
volume of anion exchange resin stirred with 20 ml water.
2. Place a 6 cm magnetic stirring bar into the beaker and stir
vigorously for 20 minutes.
3. Remove the stirring bar and allow the resin to settle to the
bottom of the beaker, waiting 20 minutes.
4. Carefully decant the milk into a second 4 liter beaker leaving
the ion exchange resin -behind. Wash the resin with distilled
water into a 600 ml beaker and save.
5. Place the magnetic stirring bar into the second 4 liter beaker,
add a second 50 ml water slurry of anion exchange resin to the
milk and stir vigorously for 20 minutes.
6. Remove the stirring bar and wait 20 minutes for the resin to
settle.
7. Carefully decant and discard the milk.
8. Wash the second batch of resin into the 600 ml beaker containing
the resin from step 4. When the combined resin has settled,
decant and discard the supernatant water.
9. Add 300 ml hot water, 80-90°C, to the combined resin, stir
briefly, and allow the resin to settle completely. Decant
1-02-2
-------
aqueous portion. Repeat the hot water wash two more times.
10. Add 100 ml 5 percent NaOCl to the resin. Place a 2 cm magnetic
stirring bar in the beaker and stir vigorously for five minutes
on a magnetic stirrer.
11. Filter the resin slurry through a filter membrane into a 1 liter
beaker and retain the NaOCl solution. See Note 3.
12. Transfer resin with 100 ml 5 percent NaOCl to a 200 ml beaker.
Stir and filter as described in steps 10 and 11. Discard the
resin.
13. Combine the two 100 ml solutions of NaOCl in the 1 liter beaker
and carefully add 40 ml 16M HN03. See Note 4.
14. Pour the acidified NaOCl solution into a 500 ml separatory funnel
and add 100 ml CC14.
15. Add 2 g of NH2OH«HC1 and shake. See Note 5.
16. Extract the iodine into the CC14 by shaking the separatory
funnel for two minutes. See Note 6.
17. Drain the lower organic phase into a clean 500 ml separatory
funnel and save.
18. Add 100 ml CC14 and 1 g NH2OH«HC1 to the aqueous phase in
the separatory funnel and shake the funnel for two minutes.
19. Combine the organic phases and discard the aqueous phase.
20. Add 50 ml water and 0.5 ml of freshly prepared 1M NaHSOj to the
separatory funnel containing the combined CC14 to reduce I2.
to I~ and shake for two minutes. Discard the lower organic
phase. See Mote 7.
21. Transfer the aqueous phase into a clean 100 ml beaker and add 1
ml 12M HC1 and 10ml of PdGl2 solution. Stir to precipitate
PdI2 and set aside for five minutes.
22. Filter with suction through a tared filter membrane using a water
wash to effect the transfer.
23. Dry the filter membrane and precipitate for 20 minutes at 110°C
and weigh to the nearest 0.1 mg.
1-02-3
-------
24. Mount the filter on a planchet and count in a low background beta
counter for 1000 minutes.
25. If net count rate is greater than 0.3 counts per minute, recount
the sample after eight days to confirm the presence of iodine-131
by decay.
26. Calculate the iodine-131 as piocuries per liter of milk at the
time of sampling. See Note 8.
Calculations
Calculate the concentration. Z, of iodine-131 in picocuries per liter
as follows:
Z =
(2.22){A)(E)(V)(R)
where
C. = gross beta counts per minute,
CB = counter background counts per minute,
A = decay correction for iodine-131 (half-life = 8.04 days),
E = beta counter efficiency,
V = volume of milk (liters),
R = fractional chemical yield based on weight of PdI2
recovered, and
2.22 = dpm per pCi.
Calculate the lower limit of detection (LLD) in picocuries per liter
as follows:
LLD= 4.66
where (2.22)(E)(R)(T)(V)
C_ = background count rate,
D
1-02-4
-------
T = counting time (same for sample and background),
E = beta counter efficiency,
R = fractional chemical yield based on weight of PdI2,
V = sample size (liters), and
2.22 = dpm per pCi.
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. Metricel is a trademark of Gelman Sciences, Ann Arbor, MI.
2. Resin should be treated to remove any fines. This is accomplished by
washing with water and allowing the resin to settle for five minutes
before decanting the water. Repeat until the fines are removed.
3. Resin should have a very light straw color after the NaOCl
extraction. If not, the NaOCl is not fresh and should be replaced.
4. Add the acid slowly with stirring until the vigorous reaction
subsides. Use a hood for this step, to remove chlorine gas.
5. Proceed with caution in step 15. Excessive gas formation during the
extraction can cause the stopcock or stopper of the separatory funnel
to disengage with loss of sample. Start by gently swirling the
solution to effect mixing. Invert the separatory funnel with funnel
stem pointing up. Relieve the pressure by opening the stopcock and
repeat this pressure-release step several times during shaking.
6. Organic phase should be deep red. If not, shake sample again after a
few minutes. Repeat this waiting period, if necessary.
7. After back extraction into the water, the CC14 should be colorless.
If not, add additional 1M NaHS03 and re-extract.
8. Milk samples may contain as much as 3 mg I" which would add to the
yield. It may be necessary to determine I" in milk with a specific
ion electrode. Iodide-specific electrodes are available from
laboratory supply companies.
1-02-5
-------
References
1. Porter, C.R., and Carter, M.W., Field Method for Rapid Collection of
Iodine-131 from Milk, Public Health Reports, U.S. Public Health
Service, 80, 453-6 (1965).
2. Thomas, C.W., Determination of Low Concentrations of Iodine-129 and
Iodine-131 in Milk Samples. Battelle Pacific Northwest Laboratories
(1974). Personal Communication.
3. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual, 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
Hew York.
1-02-6
-------
RADIOCHEMICAL DETERMINATION OF KRYPTON-8S IN ENVIRONMENTAL
AIR SAMPLES
Principle
Krypton is separated from other air constituents by passing
approximately one cubic meter of air spiked with 83mKr through a
charcoal trap at liquid nitrogen temperature and reduced pressure. The
greater part of the nitrogen and oxygen pass through the trap while
krypton and some of the other noble gases are concentrated. The remaining
nitrogen is removed by reaction with titanium at elevated temperature.
The noble gases are then transferred to a molecular sieve trap and
cryogenically fractionated. The krypton is collected on a small amount of
charcoal and subsequently transferred to a glass liquid scintillation vial
for counting.
Special Apparatus
1. Air spiking system (Figure 1).
2. Krypton separation system (Figure 2).
3. Glass liquid scintillation vials with Teflon valves and Luer
taper fittings (Figure 3).
4. Liquid scintillation counter.
5. Large volume heavy duty balloons to hold one cubic meter of air.
The air spiking system and the krypton separation system are
constructed with copper tubing and brass ferrule-type fittings.
The only glass in the systems are the flow meters, Dewar flasks, and
the liquid scintillation vials. Trap I is a 300 ml stainless-steel sample
cylinder filled with 0.3 mm dia. activated coconut charcoal. Trap II is a
70 cm length of 1.9 cm O.D. stainless steel pipe filled with 3 mm dia.
titanium sponge. Trap III is a 345 cm length of 0.95 cm O.D. copper
tubing filled with 0.3 mm dia. activated coconut charcoal. Trap IV is a
15 cm length of 0.5 cm O.D. copper tubing filled with 0.3 mm dia.
activated coconut charcoal.
Kr-01-1
-------
The Kr generator (Figure 1) is contained in a 6 cm length of 0.9
cm (O.D.) copper tubing capped at one end. 83mKr (1.86 h half-life) is
the daughter of 83Rb (83 d half life). Two ml of a 84Rb solution
83
containing approximately 0.1 mCi Rb, which has gone through several
half -lives, is evaporated to dryness in the generator container. The
container is plugged with cotton to prevent the escape of rubidium salt
particles during the equilibration procedure.
The (r generator, the reference volume (V ) and the spiking
volume (V ) are all under vacuum, and at equilibrium the activity in
V can be calculated from the activity in Vr knowing the ratio of the
two volumes. The purity of the Kr gas is checked by determining its
half-life in Vp.
Experimental results have shown that the most accurate way to
Q Om
introduce the Kr spike into the system is to nix the spike with the
air sample. Krypton recoveries range from 80 to 90 percent at an average
of 86 percent.
Reagents
Liquid scintillation cocktail [7.5 g of 2,5-diphenyloxazole (PPO) and
1.5 g of p-Bis (o-methylstyryl) benzene (bis-MSB) per liter of p-xylene].
Reflux for approximately 15 minutes before using to remove dissolved
oxygen.
Procedure— Spiking Air Samples with 83mKr (Figure 1)
Transfer approximately one cubic meter of air from compressed gas
cylinder to balloon. The volume may be approximated by measuring the
circumference of the balloon.
1. The Kr generator will have to be prepared by evacuating to a
pressure of 5 microns or less at least 24 hours before the
generator can be used. Evacuation will remove the Kr that
has been formed and it will take about 24 hours to regenerate.
Kr-01-2
-------
To prepare the generator, close valves A, 1, 6, and 7, then open
valves 2, 3, 4, and 5 to vacuum pump number 1. When the
evacuation is completed, close valves 2, 3, 4, and 5. This
operation should only be necessary again whenever the system is
not operated over an extended period of time. Open valves A, 1,
3, 4, and 5 and evacuate to a pressure of less than five microns
of mercury. Close valves 4 and 5, open valve 2, and allow the
Kr to equilibrate for about ten minutes.
2. Close valves 2, 1, A, and 3. Open valves 11, 8, 7, 4, and 6 and
start sample flow.
3. Remove liquid scintillation vial (Vr) along with valvfe A and
fill with liquid scintillation solution. (See Note 1 and Note
2.) Agitate gently to dissolve krypton in mix.
4. After the sample and spike have been transferred to the balloon,
stop the sample flow and close valves 11, 8, 7, 4, and 6. The
sample is now ready for introduction into the krypton separation
system.
Procedure--Separating Krypton From the Other Air Constituents (Figure 2)
5. Cool trap I with liquid nitrogen (LN) 30 minutes before passing
sample through. Start the spiked sample through trap I by
opening valves 33, 34, 32, 30, 28, 9, and 11. Adjust the flow
rate with needle valve C (approximately ten liters/min.).
Continue adding liquid nitrogen to trap I. While sample is
passing through trap I, perform steps 7-10.
6. Measure the volume of air passing through trap I with a wet test
meter that is connected to the exhaust vent of vacuum pump 2 .
7. To clean trap III, open valves 41, 42, 44, 45, and 47 and heat
with a wrap-around furnace for about an hour at 350°C. Remove
the heat and close valves 41, 42, 45, and 47. Before opening the
helium valve, let trap III cool for approximately 10 minutes.
Kr-01-3
-------
8. Open valves 43 and 44. When the helium flow into trap III stops,
close valves 43 and 44. After trap III cools, a partial vacuum
is formed. After cleaning trap III, the large pump is available
for cleaning trap IV.
9. To clean trap IV, open valves 21 and 20, and heat with a heat gun
for about 15 minutes. Remove the heat gun and close valves 20
and 21. Open valves 43, 16, 15, and 13. After a few seconds,
close valve 17 and open valve 18. When the helium flow into trap
IV stops, close valves, 18, 16, and 43.
10. About ten minutes before the spiked air sample has completely
passed through trap I, open valves 43, 42, 26, 25, 12, and 13 to
start the helium flow through the thermal conductivity cell
(TCC). Adjust the helium flow rate (approximately 3 liters/min.)
with needle valve D. With the helium flow rate adjusted, switch
on the TCC recorder and set recorder baseline. Then close valves
13, 12, 25, 26, 42, and 43.
11. After all the spiked sample has been removed from the balloon,
close valves 11 and 9 and warm the precooler with a heat gun.
Then close valves 28, 30, and 33. Open valves 31, 24, 12, and
13. Adjust the helium flow to three liters per minute with valve
D. Remove LN from trap I and replace with a dry ice-acetone
slush. Continue purging for one hour with helium flowing through
trap I. Cut off vacuum pump 2.
12. While trap I is being purged, open valves 41 and 40 and heat trap
II to 900°C. After several minutes, close valves 40 and 41 but
continue heating. Evacuate V$ to less than 5 microns of
mercury by opening valves 21, 22, 23, and B. Cool trap III with
LN for 20 minutes.
13. When the TCC reading returns to near the baseline setting, adjust
the helium flow to one liter per minute. Close valves 12 and 13
and open valves 26, 25, 12, 15, 16, 40, 44, 45, and 46. Remove
the dry ice-acetone Dewar from trap I and replace with an
Kr-01-4
-------
electric wrap-around furnace and heat to 350°C to transfer the
gases remaining in trap I to trap III. After about 20 minutes,
close valves 46, 16, 15, 12, and 31.
14. Shut off the furnace to trap II and open valves 38, 36, and 35.
After about a minute close valve 35 and 36. Continue heating
trap I for about an hour at 350°C making sure that it is being
evacuated by vacuum pump 2. Later, close connection to pump 2
and connect to vacuum pump 1.
15. Cool trap IV with LN and open valves 43, 44, 45, 27, 25. 12, 15,
and 17. Adjust the helium flow to about 100 ml /min. Remove LN
from trap III and replace with an ice water bath. Follow the TCC
response and about a minute before the krypton appears close
valve 17 and open valves 18 and 19. After the krypton has been
transferred from trap III to trap IV, close valves 19, 18, 15,
12, 25, 27, 45, 44, and 43. Turn off the TCC recorder.
16. To remove the excess helium from trap IV close valve 22, open
valves 20 and 21 and evacuate to less than 5 microns of mercury.
Close valve 21 and open valves 22, 23 and B. Remove LN from trap
IV and cool scintillation vial Vs with the LN. Heat trap IV
with heat gun for five minutes. Close valves B, 23, and 20.
Remove LN from the scintillation vial and warm to room
temperature. Remove the scintillation vial along with valve B
and fill with liquid scintillation solution. The time required
to this point is about four hours.
17. Count V and V for 83mKr to determine chemical recovery.
After the 83mKr has decayed, count V$ for 85Kr.
Calculations
Calculate chemical yield using the following equation:
chemical yield = Vcpm)
Vs(cpm)
Kr-01-5
-------
Since data are reported at standard temperature and pressure, volume
corrections must be made. From the gas law, pV = RT, R is constant.
Therefore,
1 .
V2=V1
-T—I —
2
where
V2 = volume at STP,
V. s measured volume in liters (from wet test meter),
T, = standard temperature 273°K,
T, = sample temperature CC * 273,
P, = measured pressure in mm of Hg, and
P9 a standard pressure, 760 mm of Hg.
Then
85Kr pCi/liter of air at STP =. Cl " CB
(2.22HEHRKV)
where
C. = beta counts per minute,
CB = background counts per minute,
E a counter efficiency,
V = volume of air (liters),
R = fractional yield based on 83mKr, and
2.22 = dpm/pCi.
Calculate the lower limit of detection (LLD) of krypton-85 in
picocuries per liter as follows:
Kr-01-6
-------
LLD
(2.22){E)(R)(V)(T)
where
E = counter efficiency,
R = fractional yield,
V = volume of air (liters),
2.22 = dpm/pCi, and
T = counting time.
Motes
1. To clean scintillation vials, pump approximately 10 ml of acetone into
the vials using a 20-ml syringe fitted with a female adapter. Expel
acetone into same syringe. Repeat two more times. Evacuate vials
until dry; then heat in oven at 100°C. Store in a desiccator until
ready for use.
2. After injecting vials with 83mKr spike or sample, fill with cooled
refluxed scintillation mix using a 20-ml syringe fitted with a female
Luer adapter.
3. A background count is obtained for each vial filled with scintillation
solution.
References
1. Shuping, R.E., Phillips, C.R., and Moghissi, A.A., "Low Level Counting
of Environmental Krypton-85 by Liquid Scintillation," Analytical
Chemistry. 41. 2082-3 (1969).
2. Moghissi, A.A., and Hupf, H.B., "A Krypton-83m Generator," Int'l J. of
Applied Rad. and Isotopes, 22, 218-220 (1971).
Kr-01-7
-------
3. Stevenson, D.L., and Johns, F.B., Separation Technique for the
Determination of Krypton-85 in the Environment; Rapid Methods for the
Measuring Radioactivity in the Environment, Proceedings IAEA-SM-148/68
Vienna 1971.
4. Curanings, S.L., Shearin, R.L., and Porter, C.R., ibid IAEA-SM-148/11.
Kr-01-8
-------
GLASS LIQUID SCINTILLATION VIAL
(REFERENCE VOLUME)
83m
Kr
GENERATOR
SPIKING VOLUME
\
SAMPLE
TO VACUUM PUMP (1)
TO Kr SEPARATION SYSTEM
TO VACUUM PUMP (2)
O BRASS BELLOWS VALVE
0-TEFLON VALVE
Figure 1. Air spiking system.
-------
THERMAL
CONDUCTIVITY CELL ,
FLOW METER
^^^
DEWAR FLASK
ICE WATER COOLED
FLOW METER
AIR SAMPLE
& SPIKE IN
PRECOOLER
(LIQUID NITROGEN
COOLED)
TO VACUUM PUMP (2)
GLASS LIQUID SCINTILLATION VIAL
(SAMPLE & SPIKE RECOVERED)
TO VACUUM
PUMP(1)
VACUUM GAUGE TUBE '—•
LIQUID NITROGEN COOLED
O BRASS BELLOWS VALVE ® NEEDLE VALVE
G- TEFLON VALVE
Figure 2. Krypton separation system.
-------
A
VIAL
CAP
6.4 cm
2.5
cm
VALVE
Figure 3. Scintillation vial assembly.
Kr-01-11
-------
RADIOCHEMICAL DETERMINATION OF PHOSPHORUS-32 IN FISH MUSCLE
Principle
The fish muscle is dried and ashed at 550°C. After wet oxidation, the
ash is solubilized and filtered. The phosphorus is decontaminated by
passing the solution over anion and cation resins. Phosphorus is
precipitated as magnesium ammonium phosphate, which is then filtered,
dried to a constant weight, and weighed. The precipitate is suspended in
a liquid scintillation solution for radioassay. Aliquots of the solution
are removed for stable phosphorus analysis to determine chemical yield.
Apparatus
1. Glass fiber filters, 47 mm.
2. Ion exchange columns. Anion 2 cm internal diameter, 10.5 cm L;
cation 2.7 cm internal diameter, 17 cm L.
3. Liquid scintillation spectrometer.
4. Liquid scintillation vials.
5. Spectrophotometer and accessories.
6. Suction filter apparatus for 47 mm filters.
Column Preparation
Anion column: 25 ml of Dowex-1 (50-100 mesh).
Charge with 100 ml 6M HC1 at a flow rate of 5 ml/minute.
Cation column: 75 ml Dowex-50W X 8 (50-100 mesh).
Charge with 250 ml 1M. HC1 at a flow rate of 5 to 10 ml/minute.
Rinse with 250 ml distilled H20.
Reagents
1. Ammonium chloride, crystalline reagent.
2. Ammonium hydroxide, 15M, NH4OH reagent.
P-01-1
-------
3. Ammonium hydroxide, 1IM. Dilute 67 ml of the NH^OH reagent to 1
liter with distilled water.
4. Ammonium hydroxide, 0.111. Dilute 6.7 ml of the NH^OH reagent
to 1 liter with distilled water.
5. Ethanol, 95 percent reagent.
6. Hydrochloric acid, 12M, 37 percent HC1 reagent.
7. Hydrochloric acid, 6M_. Dilute 500 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
8. Hydrochloric acid, 0.111. Dilute 8.3 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
9. Magnesia mixture. Dissolve 55 g MgCl2«6H20 in a minimum
amount of water. Add 140 g NH4C1 and 350 ml 15M NH4OH.
Dilute to 1 liter. Let stand 1 hour, filter, and store in glass
bottle.
10. Magnesium chloride. Reagent grade MgCl2«6H20.
11. Nitric acid, 16M, 70 percent HN03 reagent.
12. Oxidation mixture, 10 parts HN03: 1 part HC104: 4 parts
H2S04.
13. Perchloric acid, 12f1, 70 percent HC104 reagent.
14. Scintillation solution. Aqua Sol or equivalent. See Note 1.
15. Sulfuric acid, 18M, 96 percent H2S04 reagent.
Procedure
1. Dry up to 450 g fish muscle in a ceramic dish at 200°C for 12
hours. Slowly increase temperature to 400°C for a few hours.
Remove and grind ash to uniformity. Increase temperature to
550°C and ash for 24 to 48 hours.
2. Transfer ash to a 400 ml beaker. Dissolve the residue in ceramic
dish with two 15 ml portions of 16M HNO., and add rinses to
beaker containing ash.
3. Evaporate to 25 ml or until a frothy brown residue is obtained.
P-01-2
-------
4. In a perchloric add fume hood, add 20 ml of the oxidation
reagent and evaporate on a hot plate. (After the HN03 has
evaporated, dense white HC104 fumes appear and the solution
changes to a white slurry. Continue evaporating until all the
H2S04 has evaporated and the slurry changes to a shiny white
residue).
5. Dissolve the residue in 20 ml 6h1 HC1. Warm on a hot plate. Stir
with a glass rod to dissolve all the residue. Evaporate to near
dryness. Add 40 ml 6M HC1 and raise temperature to boiling while
stirring.
6. Filter the hot solution through a 47 mm glass fiber filter and
discard the filter with residue.
7. Dilute the filtrate to exactly 50 ml with 6M HC1. Remove two 0.5
ml portions for stable phosphorus determination.
8. Transfer the 49 ml solution to an anion exchange column. Rinse
sample container with a few ml of 6H HC1 and add to column. Pass
sample through at 5 ml/minute. Collect in 300 ml beaker.
9. Elute column with two 75 ml portions of 5M HC1. Collect all
fractions. (If interested in Fe determination, elute Fe with 100
ml 0.1M HC1, followed by 25 ml H20).
10. Evaporate column effluents to near dryness. When salts begin to
form (- 50 ml volume) turn heat to low to prevent bumping.
11. Dissolve the residue in 50 ml of 0.1M HC1 by heating and
stirring. Raise the temperature to boiling. Filter through
glass fiber filter and discard filter with residue.
12. Pass sample through cation exchange column at 5-10 ml/minute.
Elute column with two 75 ml aliquots of HgO. Collect the
effluents and evaporate to 100 ml volume. Take two 0.5 ml
samples for stable phosphorus yield measurement.
13. Precipitate the phosphorus as MgNH4P04 by adding 100 ml of
magnesia mixture. Cool in an ice bath. Add a few more ml
magnesia mixture to check completeness of precipitation.
P-01-3
-------
14. Filter and collect precipitate on 47 mm glass fiber filter. Wash
successively with 0.1M MH4OH and ethanoT. Place filter paper in
tared Coors crucible.
15. Dry in 100-120 *C oven for one hour. Cool, weigh, then place
filter paper and precipitate in a glass scintillation vial. This
will nearly fill the vial; then add scintillation solution, a
little at a time, until the precipitate is suspended and the vial
is full (shoulder of vial).
16. Count in liquid scintillation counter for desired amount of time.
Calculations
Calculate the concentration, Z. of phosphorus-32 in picocuries per
gram as follows:
Z . Cl - CB
(2.22(E)(Y)(W)(D)
where
C, = sample count rate,
CD = background count rate,
D
E = counting efficiency (cpm/dpn),
Y = chemical yield - colorimetric analyses of phosphorus in the
aliquots of steps 7 and 12, if no loss occurs in later steps,
W = weight of fish sample in grams,
-0.693(d)
D = decay factor = e * when d = days between
sample collection and phosphorus-32 counting, and
2.22 = dpm/pCi
Calculate the lower limit of detection (LLD) of phosphorus-32 in
picocuries per gram as follows:
P-01-4
-------
LLD= 4.66 VCBT
(2.22)(E)(Y)(W)(D){T)
where
Cn = background count rate,
D
T = counting time,
E = counting efficiency,
Y = chemical yield,
W = weight of fish (grams),
-0.693(d)
D = decay factor = e when d = days between
sample collection and phosphorus-32 counting, and
2.22 = dpm/pCi.
This LLD calculation is valid if the sample counting time is equal to
the background counting time.
Notes
1. Aqua Sol is a product of Hew England Nuclear Corp., Boston, MA.
References
1. Krieger, H.L., and Gold, S. Procedures for Radiochemical Analysis of
Nuclear Reactor Aqueous Solutions. EPA-R4-73-014, National
Environmental Research Center, U.S. Environmental Protection Agency,
Cincinnati, Ohio (May 1973).
P-01-5
-------
COLORIMETRIC DETERMINATION OF STABLE PHOSPHORUS IN BIOLOGICAL SAMPLES
Principle
An aliquot of dissolved ash is evaporated to fumes of perchloric acid
to remove fluoride and reducing agents. Ammonium vanadate and ammonium
molybdate are added and a yellow molybdovanadophosphoric acid complex is
formed which obeys Beer's law. The intensity of the yellow complex is
measured with a colorimeter at a wave length of 400 nm. The phosphorus
content of the sample is determined by comparison of its absorbance with
that of a series of phosphorus standards.
Special Apparatus
1. Colorimeter or spectrophotometer, operable at 400 nm.
2. Absorption cells, 1 cm light path.
3. Glassware.
Reagents
1. Ammonium molybdate, 0.16M Mo. Dissolve 28.1 g reagent grade
(NH4)6 Mo7024»4H20 in distilled water and dilute to
1 liter.
2. Ammonium vanadate, 0.02M V. Dissolve 1.17 g reagent grade
NH4V03 in a mixture of 17 ml 12M HC104 and 400 ml
distilled water and dilute to 500 ml.
3. Perchloric acid, 12M, 70 percent HC104 reagent.
4. Sodium chloride. NaCl reagent crystals.
5. Standard phosphorus solution, 0.1 mg P/ml. Dissolve 0.439 g
KH2P04 in distilled water and dilute to 1 liter.
Procedure
1. Pi pet an aliquot of dissolved ash which contains 0.1- 1.0 mg of
phosphorus into a 150 ml beaker. Add 5.0 ml of 12M perchloric
acid and evaporate to dense white fumes on a hot plate. See Note
1,
P-02-1
-------
2. Cool the solution and transfer with H^O to a 100 ml volumetric
flask. Add 10.0 ml of NH4V03 solution and 25.0 ml of
(NH4)gMo7024 solutioru Dilute to volume and mix well.
3. Set the colorimeter or spectrophotometer at a wave length of
400 nm and measure the cell blanks with a reagent blank prepared
in the same manner as the sample. See Note 2.
4. Measure the absorbance (A$) of the sample against the reagent
blank.
5. Carry 1.0, 2.0, 3.0,, 5.0, and 10.0 ml aliquots of the standard
phosphorus solution through the procedure. Calculate an
absorbance index (ag) for each aliquot by dividing its
absorbance by the weight of phosphorus in milligrams. The
average of these absorbance indices is used to calculate the
phosphorus content of the sample. See Note 3.
Calculations
Calculate the concentration, Z, of phosphorus in the sample in grams
per kilogram as follows:
, (A - BMCHD)
(E)(F)(G)(H)(1000)
where
A = absorbance (A),
B = cell blank,
C = sample volume in liters,
D = weight of total ash,
E = absorbance index (as),
F = sample aliquot in liters,
G = weight of ash dissolved in grams, and
H = weight of sample in kilograms.
P-02-2
-------
Notes
1. If the sample Is suspected to contain dichromate, 1 gram of NaCI is
added to the solution in Step 1. If red fumes of chromyl chloride
appear, rinse down the sides of the beaker and evaporate to fumes
again. Repeat until fumes of chromyl chloride are no longer
observed. Continue the procedure with Step 2.
2. The slit width is adjusted so that the reagent blank reads 100 percent
transmission. The cell blanks are determined by filling each cell
with the reagent blank and measuring its relative absorbance. The
cell with the lowest blank is used as a reference cell when measuring
the absorbance of the sample.
3. At least three standards should be run with each set of samples and an
absorbance index calculated. This should be used to calculate: the
phosphorus content of samples.
References
1. Cee, A. and Deitz, V. R., "Determination of Phosphate by Differential
Spectrophotometry." Analytical Chemistry 25, 1320 (1953).
2. Quinlan, K. P., and DeSesa, M. A., "Spectrophotometric Determination
of Phosphorus by Molybdovanadophosphoric Acid," Analytical Chemistry
27, (1955).
P-02-3
-------
RAUIOCHEMICAL DETERMINATION OF LEAD-210
IN WATER AND SOLID SAMPLES
Principle
Bismuth and lead carriers are added to a measured sample aliquot.
The lead is separated as a lead bromide complex by solvent extraction with
Aliquat 336 in toluene. Bismuth is separated from the lead as bismuth
oxychloride and bismuth-210 is measured in a low-background beta counter
after suitable ingrowth. The chemical recovery of lead is measured using
an atomic absorption spectrophotometer. Bismuth recovery is measured
gravi metrically.
Special Apparatus
1. Atomic absorption spectrophotometer with lead lamp.
2. Separatory funnels, 250ml capacity.
3. Combination magnetic stirrer and hot plate.
4. Low background beta counter with 7 mg/cm window.
5. Centrifuge, tal>le model.
6. Suction filter apparatus.
7. Filter paper, Whatman 42 or equivalent, 55_ mm dia. cut to fit 47
mm suction filter apparatus.
Reagents
1. Aliquat 336, methyltricaprylammonium chloride, General Mills
Chemical Co.
2. Aliquat 336, 30 percent in toluene. Mix 300 ml of Aliquat 336
with 700 ml of toluene. Just prior to use, wash solution twice
with equal volume of 1.5 M HBr.
3. Ammonium hydroxide, 15 M_.
4. Bixmuth carrier, 10 mg.B1+2/ml. Dissolve 23.2 g Bi(N03)2»5H20
in 0.8 M HN03 and dilute to 1 liter with 0.8 M HN03.
5. Ethanol, 95 percent reagent.
Pb-01-1
-------
6. Hydrobromic acid, 9 M. 48 percent HBr reagent.
7. Hydrobromic add, 3 M. Dilute 333 ml of the 48 percent HBr to 1
liter with distilled water.
8. Hydrobromic acid, 1.5 M. Dilute 167 ml of the 48 percent HBr to
1 liter with distilled water.
9. Hydrobromic acid, 0.1 M. Dilute 11 ml of the 48 percent HBr to 1
liter with distilled water.
10. Hydrochloric acid, 12 M. 37 percent HC1 reagent.
11. Hydrochloric acid, 8 M. Dilute 667 ml of the 37 percent HC1
reagent to 1 liter with distilled water.
12. Hydrogen peroxide, 50 percent H709 reagent.
+2
13. Lead carrier, 20 mg Pb /ml. Dissolve 32.0 g lead nitrate in
0.8 M HN03 and dilute to 1 liter with 0.8 M HNOj.
14. Lead standard solution, 1000 ppm Pb. Commercially available
certified standard.
15. Nitric acid, 16 M. 71 percent HN03 reagent.
16. Nitric acid, 0.8 M. Dilute 50 ml of the 71 percent HM03
reagent to 1 liter with distilled water.
17. Perchloric acid, 12 M, 70 percent HC104 reagent.
18. Toluene, reagent grade.
Sample Preparation (solid sample)
1. Add 1 ml lead carrier to weighed aliquot of sample in beaker.
2. Add 50 ml 16 M HN03 and 5 ml 50 percent H202 and digest
until sample has dissolved.
3. Evaporate sample just to dry ness and add 100 ml 3 M^ HBr and cool
to room temperature.
Sample Preparation (water sample)
1. Add 1 ml lead carrier and 5 ml 16 M HN03 to a liter water
sample. Evaporate to about 100 ml.
2. Add 100 ml 16 £1 HM03 to sample and evaporate to dryness.
Pb-01-2
-------
3. Add 25 ml 3 M HBr to sample and evaporate to dryness.
4. Add 100 ml of 3 M^ HBr to residue, heat to dissolve, and cool to
room temperature.
Procedure
1. Transfer the sample 1n 3 M HBr solution to a 250 ml separatory
funnel containing 75 ml of washed Aliquat 336.
2. Shake for 30 seconds. Let separate and discard the aqueous phase.
3. Wash the organic phase three times with 50 ml aliquots of 0.1 fl
HBr and discard all washes.
4. Strip the lead from the organic phase by shaking twice for 30
seconds with 50 ml aliquots of 12 M HC1.
5. Combine the strip solutions in a 400 ml beaker and add 100 mlf of
16 n HN03.
6. Evaporate the solution just to dryness.
7. Add 5 ml of 8 M HC1 and 5 ml of 12 M HC104 to the residue from
step 6 and heat to dryness.
8. Add 10 ml of 16 M^ HN03 to the sample and heat to dryness.
9. Add 10 ml of 12 t4 HC1 to the sample and heat to dryness.
10. Add 10 ml of 16 M HN03 and 10 ml of 12 ri HC1 and heat until
volume is reduced to approximately 10 ml.
First Milking
1. Add 1 ml of bismuth carrier to sample and transfer to a 40 ml
centrifuge tube with a distilled water rinse.
2. Adjust pH of sample to 8 with 15 ri NH4OH.
3. Heat the sample with stirring in a hot water bath.
4. Cool and centrifuge. Discard the supernate.
5. Dissolve the precipitate by first suspending in 5 drops of 12 M
HC1. Add 5 to 10 ml of distilled water to dissolve the
precipitate.
6. Add 40 ml water and heat with constant stirring.
Pb-01-3
-------
7. Cool, centrifuge, and reserve the supernate in a 250 ml beaker.
8. Repeat steps 5 through 7 twice more, combining the supernates.
Discard the precipitate, record the time and date for ingrowth of
bismuth-210. See Note 1.
9. Add 1 ml of bismuth carrier and 3 to 5 ml of 12 M HC1 to the
combined supernates. Reduce the volume to less than 100 ml.
10. Cool, transfer to a 100 ml volumetric flask and bring to volume.
11. Dilute 1 ml of sample to 10 ml in a 10 ml volumetric flask.
12. Determine the recovery of lead carrier by measuring the sample in
the 10 ml volumetric flask on an atomic absorption
spectrophotometer at 283 nm. .See Note 2.
13. Allow 2 to 3 weeks for ingrowth of bismuth-210 into the main
portion of the sample (step 10).
Second Milking
1. Transfer the solution from the 100 ml volumetric flask to a 250
ml beaker and evaporate to about 15 ml.
2. Transfer to a 40 ml centrifuge tube and adjust the pH to 8 with
15 fl NH4OH. Centrifuge and discard the supernate.
3. Dissolve the precipitate by suspending in 5 drops of 12 fl HC1 and
adding 5 to 10 ml H20. Bring volume of sample to 40 ml with
water. Record the time and date for decay of bismuth-210.
4. Heat with constant stirring in a hot water bath. Cool and
centrifuge. Reserve the supernate for additional lead-210
analysis.
5. Dissolve the precipitate by first suspending in 5 drops of 12 M^
HC1. Add 5 to 10 ml of water to complete solution. Dilute the
sample to 40 ml with water.
6. Heat in a hot water bath with constant stirring. Cool and
centrifuge. Combine the supernate with that from step 4.
7. Dissolve the precipitate as in step 5 and dilute with 40 ml of
water.
Pb-01-4
-------
8. Heat in a hot water bath with constant stirring. Cool, filter
with suction on a weighed 2.5 cm filter membrane.
9. Wash the precipitate with water and ethanol and dry the
precipitate for 30 minutes at 110 *C.
10. Cool and weigh the precipitate.
11. Count the sample using a low background beta counter with a
2
7 nig/cm window. Record the time and date for decay of
bismuth-210.
12. Standardize the counter with a known amount of lead-210 from
which bismuth-210 has been separated and prepared in the same
way as the sample.
Calculations
Calculate the concentration, Z. of lead-210 in picocuries per
milliliter or gram as follows:
Z.
where
C = cpm (net),
E = eff,
A = amount of sample (ml or g),
P = chemical yield of lead (determined by AA),
B = chemical yield of bismuth (determined gravimetrically by
weight of BiOCl),
210
I = ingrowth of Bi (time from 1st milking to 2nd milking),
210
D = decay of BI (time of separation 2nd milking in step 3
to midpoint of counting time), and
2.22 = dpm/pCi.
Pb-01-5
-------
Calculate the lower limit of detection (LLD) for lead-210 in
picocuries per milliliter or gram as follows:
LLD =
4.66V CBT
where
CB
T
E
2.22
P
B
I
D
A
background count rate (c/m),
counting time (minutes),
counter efficiency,
dpm/pCi,
chemical yield of lead (AA determination),
chemical yield of bismuth (gravimetric),
ingrowth of bismuth-210,
decay of bismuth-210, and
amount of sample (ml or g).
Motes
1. If the need arises for a fast indication of the amount of lead-210 in
a sample, the precipitate in step 8 of the first milking can be saved
on a tared filter and counted for bismuth-210. If the sample in
question has been collected for over 21 days, the results are
compatible with final results.
2. The calibration curve should have a working range of 0 to 50 ppm.
References
1. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual, 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
New York.
2. Petrow, H.G., and Cover A., "Direct Radiochemical Determination of
Lead-210 in Bone," Analytical Chemistry 37, 1659 (1965).
Pb-01-6
-------
RADIOCHEMICAL DETERMINATION OF PROMETHIUM-147
IN AQUEOUS AND URINE SAMPLES
Principle
Neodymium carrier is added to a measured sample aliquot. The rare
earths are separated by passing the sample over anion exchange resin.
Promethiun-147 is precipitated with the rare earth carrier as an oxalate.
After wet ashing, the oxalate is reprecipitated and dissolved in EOTA.
The solution is mixed with a liquid scintillation solution and the
promethium-147 is radioassayed in a liquid scintillation counter.
Special Apparatus
1. Liquid scintillation counter at ambient temperature operation.
See Mote 1.
2. Low background counting vials, 25 ml capacity. See Mote 2.
3. Ion exchange columns 3.2 cm I.D., 17 cm length.
4. Centrifuge.
5. Filter membrane, Mi Hi pore HAWP, 25 mm dia. or equivalent. See
Note 3.
6. Suction filter apparatus for 25 ram filter membrane.
Reagents
1. Ammonium hydroxide, 15 M. NH^OH reagent.
2. Anion exchange resin. Oowex 1 X 8 or equivalent, 100-200 mesh,
chloride form.
3. Aqua regia. Four parts 12 M HC1; one part 15 M HNOj by
volume. Prepare immediately before use.
4. p-Bis (o-methylstyryl) benzene (bis MSB).
5. Citric acid, crystalline reagent.
6. Citric acid, 1 M pH 4.5. Dissolve 192 g citric acid in 750 ml
distilled water and adjust to pH 4.5 with careful addition of 15
M NH4OH using pH meter. Dilute to 1 liter with distilled
water.
Pm-01-1
-------
7. Citric acid, .01 M. Dilute 5 ml of the 1 M citric acid solution
to 500 ml with distilled water.
8. 2,5-Diphenyloxazole (PRO).
9. Disodiurn ethylenediamine tetraacetic acid, 9 percent. Dissolve
90 grams reagent grade Ma2EDTA in 800 ml distilled water and
dilute to 1 liter.
10. Ethanol, 95 percent reagent.
11. Hydrochloric acid, 12 M. 37 percent HC1 reagent.
12. Hydrochloric acid, 3 M. Dilute 250 ml of the 37 percent HC1
reagent to 1 liter with distilled water.
13. Neodymium carrier, 10 mg Nd*3/ml. Dissolve 23.3 g high purity
Nd203 in 83 mi 12 M HC1 and dilute to 1 liter with distilled
water. Standardize by preparing neodymium oxalate precipitates
for weighing.
14. Nitric acid, 15 M. 70 percent HN03 reagent.
15. Oxalic acid, 1 M. Dissolve 126 g H2C204 • 2H20 in 700 ml
distilled water and dilute to 1 liter with distilled water.
16. Scintillation solution. Dissolve 7.0 g of 2,5-diphenyloxazole
(PRO) and 1.5 g of p-bis (o-methylstyryl) benzene (bis MSB) in 1
liter of p-xylene. Mix this solution with Triton M101 in a
volume ratio of 2.75 parts of p-xylene solution to 1 part of
Triton MIDI. The correct volume of Triton M101 is 364 ml for
each liter of p-xylene. Store the solution in a brown bottle and
protect from sunlight.
17. Triton N101, Rohm and Haas Co., Philadelphia, PA. See Note 4.
18. p-Xylene, scintillation grade reagent.
Procedure
1. Add 1 ml of the neodymium carrier to 10 ml of 1 M citric acid.
2. Add the above mixture to 1 liter of water sample or to 1 liter of
filtered urine with stirring. Adjust pH of sample to 4.5.
Pm-01-2
-------
3. Slurry 100 ml of am'on exchange resin with water and add to
column. Wash resin with 400 ml 3 M HC1.
4. Replace acid on column with distilled water until pH of eluate is
greater than 4.
5. Charge column with 200 ml 1 M citric acid, pH 4.5.
6. Wash column with 200 ml 0.01 M citric acid.
7. Pass urine or water sample through column at a flow rate of 10
ml/minute.
8. Pass 200 ml of 0.01 M citric acid through column at a flow rate
of 10 ml/minute.
9. Pass 400 ml of 3 M^HC1 through column. Begin with a flow rate of
2 to 3 ml per minute. Discard first 30 ml of effluent and
collect next 150 ml in a 250 ml centrifuge bottle. Remainder-of
acid can flow through more rapidly and can be discarded.
10. Replace acid on column with water until pH of eluate is greater
than 4. Column is ready for next sample beginning with step 5.
11. Add 5 ml 1 M oxalic acid to the 150 ml of column eluate in the
centrifuge bottle.
12. Adjust pH to 1.7 using 15 M NH4OH with stirring.
13. Cool contents of centrifuge bottle in an ice bath for 30 minutes
and centrifuge.
14. Discard supernate and transfer precipitate to a 40 ml centrifuge
tube and centrifuge. Discard supernate.
15. Wash precipitate with 5 ml water and centrifuge.
16. Transfer precipitate to a 100 ml beaker using distilled water.
17. Evaporate contents of beaker just to dryness and add 10 ml of
aqua regia.
18. Evaporate sample to dryness and repeat steps 17 and 18.
19. Add 10 ml 3 M HC1 to beaker and stir to dissolve residue.
20. Transfer contents to a 40 ml centrifuge tube, washing beaker with
3 M HC1, bringing volume in tube to approximately 30 ml.
Pm-01-3
-------
21. Add 2 ml 1 M^ oxalic acid to centrifuge tube and adjust pH to 1.7
using 15 M NH4OH.
22. Cool contents in ice bath for 30 minutes and centrifuge. Discard
supernate.
23. Wash precipitate with 5 ml distilled water and centrifuge.
Discard supernate.
24. Filter precipitate on weighed filter membrane.
25. Wash precipitate with 10 ml each of water and ethanol.
26. Allow precipitate to dry in desiccator and weigh.
27. Transfer precipitate and filter membrane to 50 ml beaker.
28. Add 5 ml 9 percent di sodium EDTA to beaker. Heat gently to
dissolve precipitate.
29. Transfer solution to scintillation vial, washing beaker with 5 ml
distilled water which is also put into vial.
30. Add 15 ml of scintillation solution and shake vial to mix
contents.
31. Place vial in liquid scintillation counter and allow sample to
dark adapt for two hours before counting.
32. Count sample for at least 100 minutes. See Note 5.
Calculations
Calculate the concentration. Z, of promethium-147 in picocuries per
liter as follows:
Z-
(2.22)(E)(V)(W)
where
C^ = gross counts per minute,
CB = background counts per minute,
S = standard weight of neodymium oxalate (mg),
Pm-01-4
-------
2.22 = dpn/pCI,
E = counter efficiency,
V = sample volume (liters), and
U = weight of precipitate (ing).
Calculate the lower limit of detection (LLD) in picocuries per liter
as follows:
4.66V C.J
(2.22)(E)(R)(V)(T)
where
CB = background counts per minute,
T = counting time,
2.22 = dpm/pCi,
E = counting efficiency,
R = fractional sample recovery, and
V = sample volume (liters).
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. For optimum performance of the scintillation solution, the temperature
at which the counting instrument is kept should be between 18 and 25°C.
2. Low potassium glass or plastic vials should be used to minimize
background counts. Plastic vials should be resistant to the
scintillation solution. The solvent, p-xylene, will migrate through
the plastic vials, therefore the samples should be counted no longer
than three days after preparation.
Pm-01-5
-------
3. MilHpore Is a registered tradename of Milllpore Corp., Bedford, MA.
4. Triton N101 Is a tradename for a nonylphenol polyethylene glycol ether.
5. Settings on the liquid scintillation counter should be such as to
1 A j
minimize the background count rate. A standard solution of Pm
should be used to tag at least six neodymium oxalate precipitates as
described in this procedure fn order to determine counting efficiency
of the instrument at the desired setting.
References
1. Ludwick, J. D., "Liquid Scintillation Counting of Promethium-147,
Bioassay Procedure," Analytical Chemistry 36. 1104-1106 (1964).
Pm-01-6
-------
RADIOCHEMICAL DETERMINATION OF PROMETHIUM-147 IH FECES ASH
Rapid Method
Principle
The weighed feces sample is ashed at 550°C for 72 hours. Neodymium
carrier is added and the ash is dissolved in acid. The rare earths are
precipitated as oxalate, which is dissolved in EDTA and radioassayed by
liquid scintillation counting.
Special Apparatus
1. Liquid scintillation counter at ambient temperature operation.
See Mote 1.
2. Low background counting vials, 25 ml capacity. See Note 2.
3. Filter membranes, Millipore HAWP, 25 mm dia. or equivalent. See
note 3.
4. Suction filter apparatus for 25 mm filter membrane.
5. Centrifuge.
Reagents
1. Ammonium hydroxide, 15 M_. HH^OH reagents.
2. Ammonium oxalate, crystalline reagent.
3. Ammonium oxalate, 0.5 M. Dissolve 62 g (NH4)2C204 in 800
ml distilled water with stirring while wanning. Dilute to 1
liter with distilled water. Solution should be saturated at room
temperature.
4. p-Bis (o-methylstyryl) benzene (bis MSB).
5. 2,5-Diphenyloxazole (PRO).
6. Disodium ethylenediamine tetraacetic acid, 9 percent. Dissolve
90 g reagent grade Ma2 EDTA in 800 ml distilled water and
dilute to 1 liter with distilled water.
7. Ethanol, 95 percent reagent.
Pm-02-1
-------
8. Hydrochloric acid, 12 M. 37 percent HCl reagent.
9. Neodymium carrier, 10 mg Hd+3/ml. Dissolve 23.3 g high purity
Nd203 in 83 ml 12 M HCl and dilute to 1 liter with distilled
water. Standardize by preparing neodymium oxalate precipitates
for weighing.
10. Scintillation solution. Dissolve 7.0 g of 2,5-diphenyloxazole
(PRO) and 1.5 g of p-bis (o-methystyryl) benzene (bis MSB) in 1
liter of p-xylene. Mix this solution with Triton H101 in a
volume ratio of 2.75 parts p-xylene solution to 1 part Triton
N101. The correct volume of Triton H101 is 364 ml for each liter
of p-xylene. Store the solution in a brown bottle and protect
from sunlight.
11. Triton MIDI, Rohm and Haas Co., Philadelphia, PA. See Mote 4.
12. p-Xylene, scintillation grade reagent.
Procedure
1. Ash the feces sample at 550° C for 72 hours.
2. Weigh out 1 g cooled ash into a 100 ml beaker.
3. Pipette 1.0 ml neodymium carrier into beaker.
4. Add 5 ml of 12 M HCl and heat to near boiling. Dilute with 30 ml
distilled water and heat to boiling.
5. Cool sample to room temperature and centrifuge.
6. Decant supernate into a 1 liter beaker and dilute to 250 ml with
distilled water.
7. Adjust pH of solution between 1.4 and 1.7. Add 5 ml 0.5 fl
ammonium oxalate and stir vigorously for 30 minutes.
8. Filter precipitate through a weighed filter membrane. Wash
precipitate with distilled water and ethanol.
9. Dry the precipitate at 100°C and weigh to determine recovery.
10. Dissolve the precipitate in 5 ml 9 percent disodium EDTA and
transfer to a scintillation vial using 5 ml distilled water to
transfer the solution.
Pm-02-2
-------
11. Add 15 ml scintillation solution mix and place vial in liquid
scintillation counter.
12. Allow vial to dark adapt for two hours before counting. Count
sample for 100 minutes.
Calculations
Calculate the concentration, Z, of promethium-147 in picocuries per
gram ash as follows:
(2.22)(E)(W)(P)
where
C. = gross counts per minute,
CB = background counts per minute,
S = standard weight of neodymium oxalate (mg),
2.22 = dpm/pCi,
E = counting efficiency,
W = weight of ash (grams), and
P = weight of precipitate (mg).
Calculate the lower limit of detection (LLD) for promethium-147 in
picocuries per gram ash as follows:
LLD = 4.66 v ^,
(2.22)(E)(R)(W)(T)
where
CD = background counts per minute,
D
T = counting time,
2.22 = dpm/pCi,
Pm-02-3
-------
E = counting efficiency,
R = fractional sample recovery, and
U = sample weight (grams).
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. For optimum performance of the scintillation solution, the temperature
at which the counting instrument is kept should be between 18 and 25°C.
2. Low potassium glass or plastic vials should be used to minimize
background counts. Plastic vials should be resistant to the
scintillation solution. The solvent, p-xylene, will migrate through
the plastic vials therefore the samples should be counted no longer
than three days after preparation.
3. Millipore is a trademark of the Millipore Corp., Bedford, MA.
4. Triton N101 is a tradename for a nonylphenol polyethylene glycol ether.
References
1. Ludwick, J.D., "Liquid Scintillation Counting of Promethium-147,
Bioassay Procedure," Analytical Chemistry 36, 1104-1106 (1964).
Pm-02-4
-------
RADIOCHEMICAL DETERMINATION OF PLUTONIUM IN ASHED SAMPLES.
SOIL. COAL, FLY ASH, ORES, VEGETATION. BIOTA AND WATER
Principle
The sample is ashed at 500° C for 72 hours or evaporated to a smaller
volume. Plutonium-242 tracer is added to a weighed or measured aliquot.
The solid sample is solubilized by treatment with HF, HC104, and HC1.
Plutonium is extracted from an HC1 solution of the sample into a
triisooctylamine (TIOA) solution in p-xylene. After washing the TIOA with
dilute HC1, the plutonium is stripped from the TIOA with dilute HNO-j.
The strip solution is wet ashed and the plutonium is coprecipitated with
0.1 mg lanthanum as fluoride. The precipitate is filtered on a Nuclepore
membrane and radioassayed by alpha spectroscopy for plutonium.
Special Apparatus
1. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore size
or equivalent. See Note 1.
2. Planchets, stainless steel, 32 mm diameter.
3. Plastic graduated cylinder, 100 ml capacity.
4. Separatory funnels, 1 liter capacity.
5. Suction filter apparatus for 25 mm membranes.
6. Teflon beakers. See Note 2.
7. Alpha spectrometrie system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier detector,
vacuum pump, and chamber.
Reagents
1. Ascorbic acid, reagent.
2. Ethanol, 95 percent reagent.
3. Hydrochloric acid, 12M, 37 percent reagent.
4. Hydrochloric acid, 9M. Dilute 750 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
Pu-01-1
-------
5. Hydrochloric acid, 1M_. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
6. Hydrofluoric acid, 29M, 48 percent reagent.
7. Hydrofluoric acid, 3M. Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic
graduated cylinder and storage bottle.
8. Hydrogen peroxide, 50 percent reagent grade.
9. Lanthanum carrier, 0.1 mg La* /ml. Dissolve 0.0779 g high
purity La(N03)3»6H20 per 250 ml WHC1.
10. Nickel foil, 15 cm x 1 cm x 0.1 mm.
11. Nitric acid, 1614, 70 percent reagent.
12. Nitric acid, O.M. Dilute 6 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
13. Perchloric acid, 12M, 70 percent reagent.
14. Plutonium-242 tracer solution. Approximately 1 pCi per ml
accurately calibrated.
15. Triisooctylamine (TIOA), reagent grade. K and K Chemical Div.,
ICN Pharmaceuticals, Plainview, N.Y.
16. TIOA solution in p-xylene, 10 percent. Dissolve 100 ml
triisooctylaraine in p-xylene and dilute to 1 liter with p-xylene.
17. p-Xylene, reagent grade.
Sample Preparation (ashed sample)
1. Add 1 g of ashed sample to Teflon beaker.
2. Add measured aliquot of plutonium-242 tracer solution.
3. Add 15 ml of 29M HF and evaporate to dryness. Repeat this step
two more times to remove silica as SiF^.
4. Add 5 ml of 12H HC104 and 5 ml of 9M HC1. Evaporate to
dryness. Repeat this step.
5. Add 10 ml of 12M HC1 and transfer solution to glass beaker.
Evaporate to dryness. Again add 12M HC1 and evaporate.
6. Dissolve sample in warm 9M HC1. Increase volume of 9M HC1 to 200
ml.
Pu-01-2
-------
Sample Preparation (water sample)
1. Filter the water sample of 1 to 4 liters through a fluted filter.
2. Add 100 ml of 12M HC1 and a measured aliquot of plutonium-242
tracer to the filtrate.
3. Evaporate the sample to a volume of 200 ml and add 200 ml of 12M
HC1.
Procedure
1. Add 2 ml 50 percent ^C^, heat gently and set aside for 10
minutes. See Note 3.
2. Place 100 ml 10 percent TIOA in a 1 liter separator/ funnel. Add
50 ml 9M HC1 and shake for one minute to equilibrate.
3. Drain and discard lower aqueous acid layer after clean separation
of two phases.
4. Add the aqueous sample to the TIOA in the separatory funnel and
shake the funnel vigorously for two minutes. Vent the funnel
stopcock to prevent pressure buildup in the funnel.
5. Allow the phases to separate cleanly and draw off the lower
aqueous add phase .and discard.
6. Add 50 ml of 911 HC1 to the TIOA solution in the separatory funnel
and shake for one minute.
7. Allow the phases to separate; withdraw and discard the lower acid
phase.
8. Repeat steps 6 and 7.
9. Strip the plutonium from the TIOA solution by adding 100 ml 0.1M
HN03 to the separatory funnel and shaking the funnel for two
minutes.
10. Allow the phases to separate; withdraw and transfer lower acid
phase to a clean separatory funnel.
11. Repeat steps 9 and 10 and combine strip solutions in the clean
separatory funnel.
Pu-01-3
-------
12. Add 100 ml p-xylene to the combined strip solution and shake
funnel for one minute.
13. Allow phases to separate cleanly; withdraw lower acid layer into
a beaker.
14. Evaporate combined acid solution from step 13 to dryness. Do not
overheat.
15. Add 10 ml 16M HNO^ to residue and evaporate to dryness. Do not
overheat.
16. Add 5 ml 9M^ HC1 and 5 ml 12M HC104 to residue and evaporate to
dryness.
17. Repeat step 16.
18. Add 10 ml 12M HC1 and evaporate to dryness.
19. Repeat step 18.
20. Add 50 ml 1M_ HC1 to sample and warm gently to dissolve residue.
21. Heat sample solution to 80°C with stirring and add 50 mg ascorbic
acid. Do not overheat.
22. Suspend clean nickel metal strip into the solution for two hours
to remove polonium.
23. Remove nickel and evaporate the solution to dryness.
24. Add 15 ml W HC1 to sample residue and warm to approximately 50°C.
25. Add 0.5 ml 50 percent H202, 1 ml of lanthanum carrier and 5
ml of 3f1 HF to precipitate LaF, carrying plutonium. Mix well
and set aside for 30 minutes.
26. Using suction, filter coprecipitated sample through a filter
membrane.
27. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
28. Remove clamp and top of funnel with the suction on. Allow
membrane to dry.
29. Mount membrane carefully on a 32 mm diameter planchet using
double stick tape.
30. Count sample for 1000 minutes on an alpha spectrometer.
Pu-01-4
-------
Calculations
Calculate the concentration, Z, of plutom'um in picocuries per gram as
follows:
z = (A-A^fF)
where
A = gross sample counts that appear in the plutonium-238 or
plutonium-239 alpha energy region,
A. = background counts in the same alpha energy region and time
period as A^ above,
B = gross tracer counts which appear 1n the alpha energy region
of the tracer isotope,
B. = background counts in the same alpha energy region and time
period as ]3 above,
E = alpha detector efficiency,
F = total calibrated tracer counts for same counting time as
sample counts,
W = sample weight (grams or volume In liters),
T = counting time (minutes), and
2.22 = dpm per pd.
Calculate the lower limit of detection (LLD) 1n picocuries per gram
or liter as follows:
LLD
(2.22){E)(R)(W)(T)
where
A. = background count rate,
Pu-01-5
-------
T = counting time (same for sample and background),
E = alpha detector efficiency,
R = fractional yield (B-Bj/F in calculation),
W = sample weight (grams or volume liters), and
2.22 = dpm per pCi.
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. Nuclepore is a registered trademark of Nuclepore Corp., Pleasanton, CA.
2. Teflon is a registered trademark of DuPont Co, Wilmington, DE.
3. Hydrogen peroxide stabilizes the H plutonium valence necessary for
maximum extraction in the TIOA.
References
1. Moore, F.L., "Liquid-Liquid Extraction of Uranium and Plutonium from
Hydrochloric acid Solution with Tri (iso-octyl) amine," Analytical
Chemistry 30. 908 (1958).
2. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual, 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
New York.
3. Johns, F.B., et al., Radiochemical Analytical Procedures for Analysis
of Environmental Samples, EMSL-LV-0539-17, U.S. E.P.A., Las Vegas, NY,
(1979).
Pu-01-6
-------
PREPARATION OF PLUTONIUM-236 TRACER SOLUTION
Principle
Plutonium-236 has a half-life of 2.85 years and decays to
uranium-232. In order to prevent contamination of samples with
uranium-232 and its decay products, any stock of piutonium-236 must be
periodically decontaminated before use. This should be done every 90 days.
Plutonium-236 is extracted into tri1soocty1 amine (TIOA). The
Plutonium is stripped from the TIOA with a mixture of HC1 and HF and then
wet ashed. Aliquots of the cleaned plutonium tracer are copredpitated
with lanthanum fluoride and radioassayed by alpha spectroscopy to
determine the specific activity of the tracer solution.
Special Apparatus
1. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore size
or equivalent. See Note 1.
2. Planchets, stainless steel, 32 mm diameter.
3. Plastic graduated cylinder.
4. Separatory funnels, 1 liter capacity.
5. Suction filter apparatus for 25 mm membrane.
6. Alpha spectrometric system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier detectors,
vacuum pump, and chamber.
Reagents
1. Ethanol, 95 percent reagent.
2. Hydrochloric acid, 12 H. 37 percent reagent.
3. Hydrochloric acid, 9 H. Dilute 750 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
4. Hydrochloric acid, 3 M/Hydrofluor1c acid, 0.1 M mixture. Dilute
250 ml of the 37 percent reagent grade HC1 and 3.5 ml of the 48
percent reagent grade HF to 1 liter with distilled water. Store
in a plastic bottle.
Pu-02-1
-------
5. Hydrochloric acid, 1 M. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
6. Hydrofluoric acid, 29 M_. 48 percent HF reagent.
7. Hydrofluoric acid, 3 M. Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic
graduated cylinder and storage bottle.
8. Hydrogen peroxide, 50 percent reagent grade.
+3
9. Lanthanum carrier, 0.1 mg La /ml. Dissolve 0.0799 g
La(N03)3» 6H20 per 250 ml 1 M HC1.
10. Triisooctylamine (TIOA), reagent grade.
11. TIOA solution in p-xylene, 10 percent. Dissolve 100 ml of the
triisooctylamine in p-xylene and dilute to 1 liter with p-xylene.
12. p-Xylene, reagent grade.
Procedure
1. From the specific activity of the plutonium-236 stock solution,
determine the size of the aliquot to be used, that when diluted
236
will result in a final solution of approximately 1 pCi Pu/ml.
236
2. Evaporate the aliquot of Pu to dryness in a beaker.
3. Add 10 ml of 12 M HC1 and evaporate to dryness.
4. Add 100 ml 9 M HC1 to the beaker and warm to 50°C.
5. Add 10 drops of 50 percent hydrogen peroxide to the solution.
6. Equilibrate 100 ml of the 10 percent TIOA solution with 50 ml of
warm 9 M HC1 by shaking in a separatory funnel for 1 minute.
7. Allow the layers to separate and discard the lower aqueous acid
phase.
8. Add the solution from step 5 to the TIOA in the separatory funnel
and shake funnel for 2 minutes.
9. Allow phases to separate and discard the lower aqueous acid phase.
10. Wash the TIOA solution with 50 ml 9 M HC1 warmed to 50°C. Shake
for 1 minute and discard lower aqueous acid phase when separated.
Pu-02-2
-------
11. Extract the plutonium from the TIOA with 75 ml of 3 M HC1/0.1 M
HF mixture wanned to 50°C. Shake funnel for 2 minutes.
12. Drain and save lower aqueous acid phase.
13. Repeat steps 11 and 12. Combine acid strip solution into one
clean separator/ funnel.
14. Add 100 ml p-xylene to combined strip solution and shake funnel
for one minute.
15. Allow phases to separate cleanly; withdraw lower aqueous acid
layer into a beaker. Discard p-xylene.
16. Evaporate solution from step 15 to dry ness. Do not overheat.
17. Add 10 ml 12 M HC1 to residue in beaker and take to dryness. Do
not overheat.
18. Take up solution in 250 ml 1 M HC1 and filter through a filter
membrane using suction. Place filtrate in a storage bottle.
19. Coprecipitate 1 ml aliquots of the stock solution in step 18 by
adding each aliquot to 15 ml 1 M HC1 in a beaker.
20. Add 1 ml of lanthanum carrier and 5 ml of 3 ^ HF to each beaker.
Mix well and set aside for 30 minutes to precipitate LaF3
carrying plutonium.
21. Using suction, filter coprecipitated sample through a filter
membrane.
22. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
23. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
24. Mount membrane carefully on 32 mm planchet using double stick
tape.
25. Count sample for 1000 minutes on alpha spectrometer.
Notes
1. Nuclepore is a registered trademark of Nuclepore Corp., Pleasanton, CA.
Pu-02-3
-------
References
1. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual, 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
New York.
Pu-02-4
-------
RADIOCHEMICAL DETERMINATION OF RADIUM-226 IN SOLID SAMPLES
REQUIRING FUSION
Principle
Solid samples are solubilized by fusion with a special flux. The
radium-226 in solution is determined by coprecipitation from the sample
with barium sulfate. The precipitate is solubilized and sealed in a
deemanation tube. After an ingrowth period, the radon-222 is removed into
an alpha scintillation counting cell for measurement.
Special Apparatus
1. Metricel DM800 filter membranes or equivalent, 25 mm dia., 0.8
micrometer pore size. See Note 1.
2. Magnetic stirrer and stirring bar.
3. Platinum crucibles, 20 ml with lids.
4. Suction filter apparatus.
5. Tongs for platinum crucibles.
Reagents
1. Acetone-ethanol mixture, 50 percent each reagent by volume.
2. Ammonium sulfate, 10 percent. Dissolve 10 g reagent grade
(NH)S0 in distilled water and dilute to 100 ml.
424
3. Barium chloride, 10 mg Ba+/ml. Dissolve 17.79 g BaCl2»2H20
in 1 liter distilled water.
4. Barium chloride, 2 mg Ba*2/ml. Dilute 200 ml of the 10 mg/ml
barium chloride solution to 1 liter. Filter after 24 hours.
5. Fusion flux. Mix thoroughly 15 mg barium sulfate (BaSO^),
32.9 g potassium carbonate (KgCOg), 25.3 g sodium carbonate (Na2C03),
16.8 g sodium tetraborate decahydrate {Na2B407 • 10H20).
Heat to expel water, then fuse in a platinum crucible and mix
thoroughly by swirling. Cool and grind in a porcelain mortar to
pass a 10 to 12 mesh screen. Store in an airtight bottle.
Ra-01-1
-------
6. Hydrochloric acid, 3M. Dilute 250 ml of the 37 percent HC1
reagent to 1 liter with distilled water.
7. Hydrogen peroxide, 3 percent reagent.
8. Hydrofluoric acid, 29M, 48 percent HF reagent.
9. Phosphoric acid, 15f1, 85 percent H3P04 reagent.
10. Radlum-226 standard solution, 5 to 10 pCI/ml traceable to NBS.
11. Sulfurlc acid, 18M, 96 percent H2S04 reagent.
12. Sulfurlc acid, 0.1 M. Dilute 6 ml of the 96 percent reagent
H2S04 to 1 liter with distilled water.
Procedure
1. Weigh sample using minimum of 0.5 g of soil sample and place In
platinum crucible.
2. Add flux and mix, using 8 g of flux for each gram of sample. Do
not use less than 4 g of flux (for minimum of 0.5 g soil).
3. Put I1d on crucible and place It on tripod over burner. Fuse for
30 minutes.
4. Swirl mixture at least once during fusion.
5. Remove crucible from heat with tongs and swirl mixture until it
begins to solidify.
6. Prepare the following solution in a beaker, made up as needed:
120 ml distilled water, 10 ml 18M H2S04, and 5 ml 3 percent
H202.
7. Place platinum crucible and lid in beaker. Fused sample will
dissolve away from crucible in about 30 minutes.
8. Remove crucible from solution. Rinse crucible with distilled
water and pour back into beaker.
9. Place magnetic stirring bar in beaker and begin stirring.
10. Add 50 ml dilute BaCl2 solution to beaker.
11. Stir contents of beaker for 90 minutes.
12. Remove magnetic stirring bar and wait overnight for the BaS04
to precipitate.
Ra-01-2
-------
13. Pour clear liquid off top of beaker so that entire quantity does
not have to be filtered.
14. Pour remaining liquid and precipitate into funnel attached to
suction filter. Use 0.1 M^ H2S04 as wash solution and wash
filter funnel twice with wash solution.
15. Remove clamp and lift filter funnel carefully to avoid removing
filtered precipitate. Use 1/2 filter membrane to wipe
precipitate clinging to bottom of filter funnel and place
membrane in a platinum crucible.
16. Carefully remove filter membrane from filter frit and place in
platinum crucible.
17. Add 25 drops 29M HF and 0.3 ml 10 percent (NH4)2S04
solution to the crucible.
18. Place crucible on hotplate at low temperature and evaporate
contents to dry ness.
19. Add 2 ml of acetone-alcohol mixture and burn off solvents with a
match.
20. Put top on crucible, place on tripod over burner, and heat until
ashed (about 10-15 minutes).
21. Remove from heat and add 1 ml 15M H^PO^.
22. Place crucible on hot place at low setting for 15 minutes. Turn
up to higher temperature for additional 30 minutes.
23. Hold crucible with platinum-tip tongs in the hottest part of
flame of a burner.
24. When white material dissolves and the bubbling and fumes
decrease, swirl crucible in upper part of flame for one minute.
The result is a clear material which solidifies when removed from
the heat.
25. Place crucible in hot water bath.
26. Fill crucible with 3MHC1.
27. Leaving lid off, allow liquid in crucible to evaporate slowly (2
1/2 - 3 hours) until almost completely evaporated with white
crystals remaining.
Ra-01-3
-------
28. Fill crucible approximately 1/2 full with deionlzed water and
allow the crystals to dissolve.
29. Carefully pour solution from crucible into deemanation storage
tube described In Deemanation Procedure. Rinse crucible with
deionlzed water.
30. Flame seal tube for storage as described in Deemanation Procedure.
Notes
1. Metrlcel is a trademark of Gelman Sciences Inc., Ann Arbor, MI.
References
1. Standard Methods for the Examination of Water and Waste Water, 15th
Ed., American Public Health Association, Washington, D.C. (1980).
Ra-01-4
-------
RADIOCHEMICAL DETERMINATION OF RADIUM-226 IN URINE
Principle
Barium-133 is added as a tracer to urine sample. Alkaline earth
cations are precipitated from the urine with sodium carbonate. The
precipitate containing barium and radium is further treated with nitric
acid to remove organic material. The sample is solubilized and stored in
a deemanation tube for three weeks. Radium-226 1s determined by the
De-emanation Procedure for radium-226.
Special Apparatus
1. Centrifuge.
2. Gamma ray analyzer with NaKTl) well crystal.
3. Glassware.
Reagents
1. Barium-133 tracer. Approximately 5 nCi/ml.
2. Nitric acid 16M, 70 percent HN03 reagent.
3. Nitric acid 3M. Dilute 187 ml of the reagent grade HN03 to 1
liter with distilled water.
4. Sodium carbonate, 1.5M. Dissolve 159g Na2C03 in 900 ml
distilled water and dilute to 1 liter.
Procedure
1. Add 1 ml ban'urn-133 tracer to 250 ml urine at room temperature.
2. Add 25 ml 1.5M Na2C03 and stir with a magnetic stirrer for 30
minutes.
3. Digest at 50° C for 30 minutes and cool in an ice bath.
4. Centrifuge and discard supernate. Dissolve precipitate in 10 ml
16M HN03.
5. Evaporate to dry ness and take up in 25 ml of 3^1 HN03.
Ra-02-1
-------
6. Pipette 1 ml of the sample solution Into a tube for gamma ray
counting. Compare with 1 ml barium-133 tracer to obtain chemical
yield.
7. Transfer the whole sample to a radon emanation tube. Seal and
store for three weeks.
8. Proceed with de-emanation procedure for rad1um-226.
References
1. Standard Methods for the Examination of Water and Waste Water, 15th
Ed., American Public Health Association, Washington, D.C. (1980).
Ra-02-2
-------
RADIOCHEMICAL DETERMINATION OF RADIUM-226 IN WATER SAMPLES
Principle
Rad1ura-226 in solution is determined by coprecipitation from the
sample with barium sulfate. The sample is then analyzed using the
de-emanation procedure.
Special Apparatus
1. Metricel DM-800 filter membrane, 25-mm dia., 0.8-micrometer pore
size or equivalent. See Note 1.
2. Pleated filter paper.
3. Platinum crucibles. 20 to 30 ml and lids.
4. Crucible tongs for platinum.
5. Glassware.
Special Reagents
1. Acetone-ethanol, 50 percent each by volume.
2. Ammonium sulfate, 10 percent. Dissolve 10 g (NH4)2S04 in
distilled water and dilute to 100 ml with distilled water.
3. Barium chloride stock solution, 10 mg Ba /ml. Dissolve 17.79 g
BaCl9»2H,0 in 1 liter of distilled water.
e. c +2
4. Barium chloride dilute solution, 2 mg Ba /ml. Dilute 200 ml
of the barium chloride stock solution to 1 liter in a volumetric
flask with distilled water.
5. Hydrochloric acid, 12M: 37 percent HC1 reagent.
6. Hydrochloric acid, 3M_. Dilute 250 ml of the reagent grade HC1 to
1 liter with distilled water.
7. Hydrofluoric acid, 29J1: 48 percent HF reagent.
8. Phosphoric acid, 15M: 85 percent H3P04 reagent.
9. Radium-226 standard solution, approximately 5 to 10 pCi/ml,
traceable to the National Bureau of Standards.
10. Sulfuric acid, 18M: 96 percent HgS04 reagent.
Ra-03-1
-------
11. SuIfuric acid, 0.05M. Dilute 1.6 ml of the H2S04 reagent to
1 liter with distilled water.
Procedure
1. If water sample Is not clear, filter a one liter aliquot through
a pleated filter paper. Save any precipitate if the radium
content of the precipitate is needed. It is then analyzed using
the procedure for solid samples.
2. Place the water sample in a 1.5 liter beaker, add a magnetic
stirring bar and place on a stlrrer.
3. Add the following to the water sample with stirring: 20 ml 12M
HC1, 50 ml dilute BaClg reagent, and 20 ml 18M H2S04.
4. Cover sample and allow to stir for a minimum of 30 minutes to
precipitate BaS04.
5. Remove magnetic stirring bar and allow mixture to stand overnight.
6. Decant clear liquid off the top so that entire quantity does not
have to be filtered.
7. Decant remaining liquid and precipitate into funnel attached to
suction filter. Use 0.05M H2S04 as wash solution and wash
filter funnel twice with wash solution.
8. Remove clamp and lift filter funnel carefully to avoid removing
filtered precipitate. Use half of a filter membrane to wipe
precipitate clinging to bottom of filter funnel and place
membrane in a platinum crucible.
9. Carefully remove filter membrane from the filter apparatus and
place in platinum crucible.
10. Add 25 drops 29M HF and 0.3 ml 10 percent (NH4)2S04
solution to volatilize silica as S1F4.
11. Place crucible on hotplate at low temperature and take to dryness.
12. Add 2 ml of acetone-alcohol mixture and burn off solvents with a
match.
Ra-03-2
-------
13. Put top on crucible, place on tripod over burner, and heat until
ashed (about 10-15 minutes).
14. Remove from heat and add 1 ml 15f1 H3P04.
15. Place crucible on hot plate at low setting for 15 minutes. Turn
up to higher temperature for additional 30 minutes.
16. Hold crucible with platinum-tip tongs in the hottest part of
flame of a burner.
17. When white material dissolves and the bubbling and fumes
decrease, swirl crucible in upper part of flame for one minute.
The result is a clear material which solidifies when removed from
the heat.
18. Place crucible in hot water bath.
19. Fill the crucible almost full with 3M HC1.
20. Leaving lid off, allow liquid in crucible to evaporate slowly (1
1/2 - 3 hours) until almost completely evaporated with white
crystals remaining.
21. Fill crucible approximately half full with deionized water and
allow the crystals to dissolve.
22. Carefully pour solution from crucible into de-emanation storage
tube described in De-emanation Procedure. Rinse crucible with
distilled water.
23. Flame seal tube for storage as described in the Rad1um-226
De-emanation Procedure and proceed.
Notes
1. Metricel is a trademark of Gelman Sciences, Inc., Ann Arbor, MI.
References
1. Standard Methods for the Examination of Water and Waste Water, 15th
Ed., American Public Health Association, Washington, D.C. (1980).
Ra-03-3
-------
RADIOCHEMICAL DETERMINATION OF RADIUM-226
De-emanation Procedure
Principle
After sample preparation is completed, individual samples are sealed
in disposable storage tubes. Radon-222 ingrowth proceeds through three
weeks storage of the tubes. The tubes are then connected to a gas
manifold and the accumulated radon-222 is swept into evacuated Lucas alpha
scintillation counting cells. The alpha activity in the cells is measured
after five hours ingrowth of radon-222 progeny.
Special Apparatus
1. De-emanation manifold assembly.
2. Lucas alpha scintillation cells.
3. Photomultiplier tube assembly and associated electronics.
4. Tank of nitrogen.
5. Glass-sealing torch.
6. Vacuum pump assembly.
7. Pyrex brand glass tubing, 15-mm inside diameter, 60-cm lengths.
8. Acid dichromate cleaning solution.
9. Vinyl tubing, 1.3 cm inside diameter, 1.6 cm outside diameter.
Procedure
1. Clean 60-cm lengths of glass tubing in dichromate cleaning
solution and dry.
2. Flame seal one end of the individual sections of the glass tubing.
3. Starting approximately 10 cm from the open end of a section of
the tubing, soften the tubing in a flame and form a constriction
approximately 6.5 cm long and 0.6 cm diameter.
4. Transfer prepared sample to de-emanation tube using distilled
water as wash. Fill to within 1.3 cm of constriction.
Ra-04-1
-------
5. Flame seal tube at constriction without overheating.
6. Store sample-containing sealed tubes for at least 21 days.
7. Soak one end of each of two 9 cm long by 1.25 cm in diameter
pieces of vinyl tubing in acetone until slight swelling occurs.
8. Place a serum stopper in the solvent treated end of each piece of
tubing so that the tubing surrounds the sleeve of the stopper.
9. Insert 26-gauge hypodermic needles in the rubber serum stoppers.
10. Soak the other ends of the vinyl tubing in acetone until swelling
is evident.
11. Slip the sol vent-treated tubing over the sealed end of the sample
tube. Leave the needle inserted in the stopper to relieve
pressure as tubing dries.
12. Remove needles from stoppers after 24 hours.
13. Evacuate Lucas scintillation cells by inserting needle connected
to vacuum line through stopper attached to neck of cell.
14. Disconnect cell from vacuum line with vacuum pump operating.
15. Set up radon transfer manifold as shown in the cell evacuation
illustration (Figure 1).
16. Insert needle from vacuum line into lower stopper of the vacuum
tube. Insert needle attached to vacuum gauge into the same
stopper.
17. Remove vacuum line needle and check gauge for possible leak.
18. Reapply vacuum to tube and close upper valve.
19. Insert needle from vacuum line into upper stopper of the sample
tube being careful not to break tip of tube with needle.
20. Repeat step 19 for other end of sample tube.
21. Allow 10 minutes to elapse in order to check for air leaks at
both ends of sample tube. A leak is indicated by partial
refilling of the collapsed vinyl tubing.
22. Attach sample cell to manifold as shown in purging illustration
(Figure 2).
23. Break both top and bottom tips of sample tube using long nose
pliers.
Ra-04-2
-------
24. Record time.
25. Put rubber sealant on the vinyl tubing in the area of the broken
glass tips as a precaution against puncture of the tubing.
26. Cautiously open top valve to permit pressure equalization between
sample tube and Lucas cell, being careful not to draw up sample
liquid into drying tube.
27. Close upper valve.
28. Start nitrogen purge with flow rate barely detectable through
hole in tubing.
29. Flush valve, and, with valve closed, insert needle from flow tube
into lower stopper of sample tube.
30. Cautiously open lower valve to control flow of nitrogen into
sample tube. The bubble rate should be between 15 and 45 per
minute.
31. For a period of 30 minutes open upper valve briefly in order to
equalize pressure between Lucas cell and sample tube.
32. After 30 minutes, open upper valve completely and open lower
valve to increase bubble rate.
33. When nitrogen flow has stopped and vinyl tubing has expanded to
shape, simultaneously remove needles from stoppers of Lucas cell
and lower stopper of sample tube.
34. The Lucas cell is stored for 5 hours prior to counting for
ingrowth of radon-222 progeny.
35. Count the sample for 1000 minutes.
36. Dispose of needles and drying tube.
37. Clean upper valve by the following steps: (a) disassemble valve,
(b) submerge in acetone and rinse with water, (c) submerge in
mineral spirits, (d) wash in hot soapy water and rinse, and
(e) dry in oven at 75° C.
Calculations
Calculate the concentration^, of radium-226 in picocuries per liter
Ra-04-3
-------
as follows:
C1-CB
(2.22MEMV) 1-e "All e 'At2 1-e ~^2
where
x = decay constant for radon-222 (t 1/2 = 3.825 days),
t, = time interval allowed for ingrowth or radon from radium,
t2 = time interval between de-emanation and counting,
tj = counting time,
C. = observed count rate of sample,
CB = background count rate,
E = calibration constant of the scintillation cell in counts per
unit time per picocurie of radon plus decay products (All of
the corrections can be obtained directly or indirectly from
Table 1),
V = sample volume (liters), and
2.22 = dpm/pCi.
Sample Calculation
Assume the following data:
t, = 13d., 14 h., 6 m,
t- = 4 h., 15 m,
t3 = 16 h., 30 m,
C. = 199.2 counts/hour,
CB = 9.3 counts/hour, and
E =151.1 counts/hour/dpm. See Note 1.
Ra-04-4
-------
From Table 1,
1-e "Xtl= 1. - 0.09484 x 0.89969 x 0.99925 = 0.91474,
e ~xt2 = 0.97025 x 0.99811 = 096842, and
Xt3/ (l-e"xt3) = 1.06358 (by linear interpolation).
From these data,
pCi Ra = (199.2 - 9.3) x 1 x 1 x 1.06358 = 0.680.
(151.1) (2.22) 0.91474 0.96842
Calculate the lower limit of detection (LLD) in picocuries per liter
as follows:
LLD
(2.22)(E)(V)(T)
where
CB = background count rate,
T = counting time, and
E = calibration constant of the scintillation cell in counts per
unit time per picocurie of radon plus decay products in
counts per hour per dpm.
This LLD is valid if the background counting time is approximately
equal to the sample counting time.
Notes
1. The calibration constant is determined by sealing a known quantity of
radium-226 in a de-emanation tube. After 21 days storage, the radon
Ra-04-5
-------
Is transferred to a Lucas cell and counted. The Lucas cells are
Individually calibrated. The radium-226 used Is traceable to the
National Bureau of Standards. Approximately 5-10 of radium-226,
accurately known, 1s used for each calibration.
References
Blanchard, R.L., An Emanation System for Determining Small Quantities
of Radium-226, U.S. Department of Health, Education, and Welfare,
Public Health Service Publication No. 999-RH-9 (1964).
Ferri, E., Magno, R.J., and Setter, L.R., Radionuclide Analysis of
Large Numbers of Food and Water Samples, U.S. Department of Health,
Education, and Welfare, Public Health Service Publication Number
999-RH-17 (1965).
Standard Methods for the Examination of Water and Waste Water, 15th
Ed., American Public Health Association, Washington, D.C. (1980).
Rushing, D.E., The Analysis of Effluents and Environmental Samples
from Uranium Hills and of Biological Samples for Uranium. Radium and
Polonium. SM/41-44. Symposium of Radiological Health and Safety,
Vienna, Austria (August 1963).
Ra-04-6
-------
TABLE 1
A. Decay of Radon (in minutes, hours, and days)
B. Growth of Radon from Radium (in days).
C. Multiplicative Factor for Correction of Radon
Activity for Decay during Counting (in hours)
(Based on 3.825 days as half-life of radon)
Time
0
1
2
3
4
5
G
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Minutes
1.000,00
0.999,87
0.999,75
0.999,62
0.999,59
0.999,37
0.999,25
0.999,12
0.998,99
0.998,87
0.998,74
0.998,62
0.998,49
0.998,37
0.998,24
0.998,11.
0.997,99
0.997,86
0.997,74
0.997,61
0.997,49
0.997,36
0.997,24
0.997,11
0.996,99
0.996,86
A. e'xt
Hours
1.000,00
0.992,48
0.985,01
0.977,60
0.970,25
0.962,95
0.955,71
0.948,52
0.941,39
0.934,31
0.927,27
0.920,31
0.913,38
0.906,51
0.899,69
0.892,93
0.886,21
0.879,55
0.872,93
0.866,36
0.859,85
0.853,38
0.846,96
0.840,59
0.834,27
0.827,99
Days
1.000,00
0.834,27
0.696,00
0.580,65
0.484,42
0.404,14
0.337,16
0.281,28
0.234,66
0.195,77
0.163,33
0.136,26
0.113,68
0.094,84
0.079,12
0.066,01
0.055,07
0.045,94
0.038,33
0.031,98
0.026,68
0.022,25
0.018,57
0.015,49
0.012,92
0.010,78
B. l-e'xt
Days
0.000,00
0.165,73
0.304,00
0.419,35
0.515,58
0.595,86
0.662,84
0.718,72
0.765,34
0.804,23
0.836,67
0.863,74
0.886,32
0.905,16
0.920,88
0.933,99
0.944,93
0.954,06
0.961,67
0.968,02
0.973,32
0.977,75
0.981,43
0.984,51
0.987,08
0.989,22
xt
C. l-ext
Hours
1.000,00
1.003,72
1.007,54
1.011,39
1.015,16
1.018,98
1.022,83
1.026,65
1.030,51
1.034,36
1.038,23
1.042,10
1.045,97
1.049,88
1.053,79
1.057,69
1.061,61
1.065,54
1.069,49
1.073,44
1.077,40
1.081,37
1.085,35
1.089,34
1.093,33
1.097,34
Ra-04-7
-------
TABLE 1 (Continued)
xt
Time A. e~xt B. 1-e-** C. ]
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Minutes
0.996,73
0.996,61
0.996,48
0.996,36
0.996,23
0.996,11
0.995,98
0.995,86
0.995,73
0.995,61
0.995,48
0.995,36
0.995,23
0.995,11
0.994,98
0.994,85
0.994,73
0.994,60
0.994,48
0.994,35
0.994,23
0.994,10
0.993,98
0.993,85
0.993,73
0.993,60
0.993,48
0.993,35
0.993,23
0.993,10
0.992,98
0.992,85
0.992,73
0.992,60
0.992,48
Hours
0.821,77
0.815,58
0.809,45
0.803,36
0.797,32
0.791,32
0.785,37
0.779,46
0.773,60
0.767,78
0.762,01
0.756,28
0.750,59
0.744,94
0.739,34
0.733,78
0.728,26
0.722,78
0.717,34
0.711,95
0.706,59
0.701,23
0.696,00
0.690,77
0.685,57
0.680,42
0.675,30
0.670,22
0.665,18
0.660,18
0.655,21
0.650,28
0.645,39
0.640,54
0.635,72
Days
0.008,99
0.007,50
0.006,26
0.005,22
0.004,36
0.003,63
0.003,03
0.002,53
0.002,11
0.001,76
0.001,47
0.001,23
0.001,02
0.000,85
0.000,71
0.000,59
0.000,50
0.000,41
0.000,34
0.000,29
0.000,24
0.000,20
0.000,17
0.000,14
0.000,12
0.000,10
0.000,08
0.000,07
O.OOO.OG
0.000,05
0.000,04
0.000,03
0.000,03
0.000,02
0.000,02
Days
0.991,01
0.992,50
0.993,74
0.994,78
0.995,64
0.996,37
0.996,97
0.997,47
0.997,89
0.998,24
0.998,53
0.998,77
0.998,98
0.999,15
0.999,29
0.999,41
0.999,50
0.999,59
0.999,66
0.999,71
0.999,76
0.999,80
0.999,83
0.999,86
0.999,88
0.999,90
0.999,92
0.999,93
0.999,94
0.999,95
0.999,96
0.999,97
0.999,97
0.999,98
0.999,98
Hours
1.101,36
1.105,39
1.109,45
1.113,47
1.117,52
1.121,58
1.125,66
1.129,74
1.133,83
1.137,94
1.142,05
1.146,17
1.150,30
1.154,44
1.158,59
1.162,75
1.166,92
1.171,09
1.175,28
1.179,47
1.183,68
1.187,89
1.192,12
1.196,35
1.200,60
1.204,85
1.209,11
1.213,38
1.217,66
1.221,95
1.226,25
1.230,56
1.234,88
1.239,21
1.243.54
Ra-04-8
-------
18 ga. needles
(glued)
Lucas
Scintillation
Cell
Magnesium
Perchlorate
18 ga. needles
H/468L
adapter
ML/ML sliplock
adapter
To Vacuum
I
Figure 1. Cell evacuation assembly.
Ra-04-9
-------
18 ga. needles
(glued)
18 ga. needles
Tygon tubing
ML/ML
sliplock
adapter
H/468L
adapter
From Nitrogen
Lucas
Scintillation
Cell
Magnesium
Perch I orate
ML/ML sliplock
adapter
Sample
26 ga. needle
Figure 2. Cell purging assembly.
Ra-04-10
-------
20mm
^MMMI
^M^M
90mm
Phosphor
Coated
Clear Silica
Window
Serum Stopper
Brass Collar
Kovar Metal
iXVVVVVVWVXVXV
50mm
Figure 3. Lucas type scintillation cell.
Ra-04-11
-------
RADIOCHEMICAL DETERMINATION OF RADIUM-228 IN WATER SAMPLES
Principle
The radium solution from the radium-226 determination is saved and
the radium is reprecipitated as a radium-barium sulfate. This precipitate
is dissolved in a pentasodium diethylenetriamine pentaacetate solution.
The radium-228 is a weak beta emitter and decays to actinium-228, which is
allowed to ingrow for three days. The actinium-228 is then extracted with
Di-2-ethylhexylphosphoric acid and back-extracted with nitric acid. The
actinium-228 is beta counted in a low background proportional counter.
Special Apparatus
1. Centrifuge.
2. Planchets, stainless steel, 5 cm diameter.
3. Separatory funnels, 125 ml, 2 liter capacity*
4. Magnetic stirrer and stirring bars.
5. Glassware.
6. Suction filter apparatus.
Reagents
1. Acetic acid, glacial 17.4M_. HC2H302 reagent.
2. Acetic acid 6M. Dilute 345 ml of the reagent grade HC2H302
to one liter with distilled water.
3. Actinium wash solution. Dissolve 100 g monochloroacetic acid and
2.4 ml of 41 percent NagDTPA in 800 ml of distilled water and
dilute to 1 liter. Adjust the pH to 3.0 with NaOH pellets
(approximately 25.4 g NaOH).
4. Ammonium hydroxide 15M. Reagent grade NH.OH.
~~ +2
5. Barium carrier, 10 mg Ba /ml. Dissolve 17.78 g BaCl2«»2H20 in
800 ml distilled water and dilute to 1 liter. Allow to stand 24
hours and filter.
+2
6. Barium carrier, 5 mg Ba /ml. Dissolve 4.45 g BaCl2»2H20
Ra-05-1
-------
in 400 ml distilled water and dilute to 500 ml.
7. Bismuth carrier, 20 mg Bi*3/ml. Dissolve 46.4 g Bi(N03)3« 5H20
in 800 ml distilled water and dilute to 1 liter.
8. Chloroacetic acid, 2NL Add 189 g of reagent grade chloroacetic
acid to a beaker, dissolve in distilled water and dilute to 1
liter.
9. Diammmonium citrate, 2Mk Dissolve 226.2 g dibasic ammonium
citrate, (MH4)2HCgH507, in distilled water and dilute
to 500 ml.
10. Di-2-ethyIhexylphosphoric acid, HDEHP, 15 percent in n-heptane.
Dilute 150 ml HDEHP to 1 liter with n-heptane and transfer to a
2-liter separator^ funnel. Wash the HDEHP twice with 200 ml
aliquots of a 1:1 mixture of 2M diammonium citrate and 15^4
NH4OH. The mixture is prepared by adding 100 ml 15M NH4OH to
100 ml 2J1 di ammonium citrate in a beaker and mixing. Add to the
separatory funnel containing the HDEHP. Shake for one minute,
releasing pressure frequently. Allow the layers to separate and
discard lower layer. Wash the HDEHP twice with 4M HN03,
discarding the lower layer each time after shaking for one
minute. Store the cleaned HDEHP in a polyethylene bottle.
Immediately before using the HDEHP solution, the amount to be
used is washed first with an equal volume of distilled water and
then with one-half the volume of actinium wash. The lower layers
are discarded each time after shaking for one minute.
11. Diethylenetriamine pentaacetic acid, pentasodium salt, Na5
DTPA, 41 percent reagent solution.
12. Diethylenetriamine pentaacetic acid, pentasodium salt, Na5DTPA,
0.1714, pH 10. Add 209 ml of the 41 percent Na5 DTPA solution
to 400 ml of distilled water and filter through glass wool with
suction. Dilute to 1 liter with distilled water and adjust to pH
10 using either perchloric acid or sodium hydroxide (usually
requires 10 to 12 ml perchloric acid). Store in a polyethylene
bottle.
Ra-05-2
-------
13. n-Heptane. Reagent grade.
14. Hydrochloric acid, 12M, 37 percent HC1 reagent.
15. Hydrochloric acid, Itt. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
+2
16. Lead carrier, 100 mg Pb /ml. Dissolve 160 g reagent grade
Pb(N03)2 in 800 ml distilled water and dilute to 1 liter.
17. Nitric acid, 16M, 70 percent HN03 reagent.
18. Nitric acid, 4M. Dilute 250 ml of the 70 percent reagent grade
HU03 to 1 liter with distilled water.
19. Nitric acid, 1M. Dilute 63 ml of the 70 percent reagent
grade HN03 to 1 liter with distilled water.
20. Perchloric acid, 12M, 70 percent HC104 reagent.
21. Sodium hydroxide. Reagent grade pellets.
22. Sodium sulfate, 20 percent. Dissolve 20 g anhydrous Na2S04
in 80 ml distilled water and dilute to 100 ml.
23. SuIfuric acid, 18M, 96 percent H2S04 reagent.
24. Sulfuric add, 4M. Dilute 222 ml of the 96 percent reagent grade
H2S04 to 1 liter with distilled water.
Procedure
Transfer 1,000 ml of the water to a 1,500 ml beaker. Adjust the
pH to approximately 1.0 with 16M HN03 and add 200 mg of lead
carrier.
Add 100 ml 18M H2S04 and heat to 70°C with stirring for one
hour. Allow the lead sulfate to settle overnight.
Carefully decant as much clear liquid as possible without losing
any precipitate. Pour equal volumes of the remaining liquid Into
two centrifuge tubes of equal volume (40-ml or 100-ml).
Centrifuge and decant supernate. If necessary, repeat until all
precipitate has been collected 1n the two centrifuge tubes.
Slurry the precipitate in one tube with 4M H2SO. and transfer
quantitatively to the other tube using 4M H2S04 as wash.
Ra-05-3
-------
Centrifuge and discard the supernate.
4. Place a stirring bar In the tube containing the PbSO^, add 1 ml
of glacial acetic acid, 6 ml of 41 percent DTPA, and 1 ml
distilled water. Heat with stirring until dissolution 1s
complete.
5. Add with stirring, 20 mg bismuth carrier and 2 ml 18M HgSO^.
Digest 5 to 10 minutes In a hot water bath, cool, centrifuge, and
discard supernate. See Note 1.
6. Add 15 ml of 0.17M^ DTPA to the precipitate, place 1n a boiling
water bath and heat with stirring to dissolve the precipitate
(dissolution may require 20 minutes).
7. When the precipitate has dissolved In step 6, add 1 ml of barium
carrier (10 mg/ml), 1 ml Na2S04 (20 percent), dilute to 28 ml
with distilled water, and then add 2 ml of 6M acetic acid. Heat
In a hot water bath for five minutes while stirring with a
magnetic stirring bar.
8. Transfer to an 1ce bath. Allow to cool for five minutes with
stirring. Remove stirring bar and centrifuge. Decant and
discard supernate.
9. Repeat steps 6, 7, and 8 omitting the addition of Ba* In step
7. Record the time the acetic acid 1s added. See Note 2.
10. To the BaS04 precipitate, add 15 ml 0.17M DTPA, heat and stir
until all dissolves.
11. Allow solution to cool, stopper centrifuge tube and store for at
least 36 hours to allow for Ac-228 Ingrowth.
12. After the Ingrowth period, place sample In a boiling water bath,
Insert a magnetic stirring bar and stir until any precipitate
that may have formed during the Ingrowth period has dissolved.
Then add 1 ml 20 percent Na2S04, dilute to 28 ml with
distilled water and add 2 ml of 6M acetic add. Record time.
See Note 3.
Ra-05-4
-------
13. Allow mixture to heat in the boiling water bath for five minutes
with stirring, then remove stirring bar and place centrifuge tube
in an ice bath for five minutes. Centrifuge and decant supernate
into a clean 40-ml centrifuge tube. Rinse walls with 2 to 3 ml
of water, exercising care not to disturb precipitate. Add wash
to the tube containing the supernate.
14. Add 1 ml of barium carrier (5mg/ml) to the centrifuge tube
containing the supernate. Heat with stirring in a boiling water
bath for five minutes. Cool in a ice water bath for five minutes
and centrifuge. See Note 4.
15. Quantitatively transfer supernate to a 100-ml beaker containing 5
ml of 2M monochloracetic acid. Measure the pH to confirm that it
is 3.0. See Note 5.
16. Transfer the solution to a 125-ml separatory funnel. Add 100 ml
of cleaned and actinium washed 15 percent HDEHP using a portion
to wash the 100-ml beaker. See Note 6.
17. Shake vigorously for two minutes (relieve pressure as needed).
Allow layers to separate and discard lower (aqueous) phase.
18. Add 10 ml of the actinium wash solution. Shake for one minute,
allow layers to separate and discard lower (aqueous) layer.
19. Repeat step 18.
20. Add 10 ml of 1M_ HNOj. Shake for one minute, allow layers to
separate, and collect lower layer in an 80-ml beaker.
21. Repeat step 20 using 5 ml of 1M HNO-j. Combine lower aqueous
layer in 80-ml beaker containing aqueous fraction from step 20.
Discard organic phase.
22. Evaporate solution to dryness on a 5 cm planchet. Continue
heating planchet until all nitric acid vapors have been removed.
23. Count sample and compute Ra-228 concentration. See Note 7.
Ra-05-5
-------
Calculations
Calculate the concentration. Z, of radium-228 in picocuries per liter
as follows:
C1-CB
(2.22)(Y)(E)(V) (l-e'u-11JLl) (e'°'113t2)
where
C^ = sample count rate,
Cg = background count rate,
Y = chemical yield based on counting rate of spike added and
recovered (see Note 7),
E = beta counting efficiency,
V = sample size (liters),
tj = actinium-228 period of ingrowth from radium-228 (hours) (see
steps 9 and 12),
tg = actinium-228 decay period (hours) measured from the actinium
separation (step 12) to the mid-time of the beta count, and
2.22 = dpm/pCf.
Calculate the lower limit of detection (LLD) in picocuries per liter
as follows:
LLD =
(2.22){Y)(E)(V)(T)
where
Y = chemical yield,
E = beta, counting efficiency,
V = sample volume (liters), and
T = counting time.
Ra-05-6
-------
This LLD calculation Is valid if the sample counting time Is equal to
the background counting time.
Notes
1. If Ra-226 is determined by de-emanation of Rn-222 between steps 4 and
5, the supernate will contain the B1-210 that grew in during the
30-day Rn-222 ingrowth period and can be used to determine Pb-210 (For
a 30-day ingrowth period, B1-210 will be 98.4 percent of its
equilibrium value).
2. Steps 6, 7, and 8 are performed to remove all Ac-228 present. The
second BaSO^ precipitation with acetic acid provides an actinium
free precipitate and begins the measured ingrowth of the Ac-228 from
the Ra-228 present.
3. The precipitation of BaS04 in step 10 isolates the actinium in the
supernate and ends the Ac-228 ingrowth period.
4. The second BaS04 precipitation insures complete removal of the
radium.
5. It is important that the pH of the solution containing the actinium is
3.0. If necessary, adjust pH with additional 2^ monochloracetic acid.
6. It is Important that the HDEHP be washed with an equal volume of
distilled water and half volume aliquot of actinium wash solution
immediately prior to using.
7. There is no isotope of actinium available to monitor the chemical
yield of Ac-228. To determine the chemical yield, a second 1-liter
sample of acidified water is spiked with a known quantity of Ra-228
and analyzed in the exact manner and at the same time as the unknown
sample. The chemical yield determined for the spiked sample Is
assumed equal to that for the unknown sample. The spiked sample
should be analyzed with each batch of unknown samples.
Ra-05-7
-------
References
1. Johnson, J.O., Determination of Radlum-228 in Natural Waters.
Radiochemical Analysis of Water, Geological Survey Water-Supply Paper
1696-G., U.S. Government Printing Office, Washington, D.C., (1971).
2. Percival, D.R. and Martin, D.B., "Sequential Determination of
Radium-226, Radlum-228, Actinium-227, and Thorium Isotopes in
Environmental and Process Waste Samples," Analytical Chemistry, 4£
1742-1749, (1974).
3. Krieger, H.L., and Whittaker, E.L., Prescribed Procedures for
Measurement of Radioactivity in Drinking Water, EPA-600/4-80-032,
Environmental Monitoring and Support Laboratory, Office of Research
and Development, U.S. Environmental Protection Agency, Cincinnati,
Ohio (August 1980).
Ra-05-8
-------
RADIOCHEMICAL DETERMINATION OF RADIOSTRONTIUM IN FOOD ASH AND
OTHER SOLID SAMPLES
Principle
Barium, calcium and strontium carriers are added to the ashed
sample. Magnesium is precipitated and removed from the sample at pH 3.8.
Barium and strontium are adsorbed on a cation exchange resin allowing
calcium to pass through. The barium and strontium are selectively eluted
and the strontium is precipitated. Strontium-89 and strontium-90 are
radioassayed separately by measuring the Ingrowth of yttrlum-90.
Special Apparatus
1. Graduated separatory funnel as reservoir for column, 1 liter
capacity.
2. Ion exchange column, 2.5 cm Internal diameter, 18 cm in length.
3. Metricel DM800 membrane filters or equivalent, 25 mm diameter,
0.8 micrometer pore size. See Note 1.
4. Nickel crucible, 250 ml volume and lid.
5. Stainless steel planchets, 5 cm diameter.
6. Suction filter apparatus.
7. Centrifuge, floor model.
8. Glassware.
9. Blast burner.
10. pH meter.
11. Magnetic stirrer.
Reagents
1. Ammonium hydroxide, 15M. Reagent grade NH^OH.
2. Ammonium hydroxide, 6M. Dilute 405 ml NH4OH reagent to 1 liter
with distilled water.
3. Barium carrier, 5.0 mg Ba*2/ml. Dissolve 9.5 g Ba(N03)2 in
900 ml of distilled water. Add 1 ml of 16M HN03 and dilute to
Sr-01-1
-------
1 liter with distilled water.
4. Calcium nitrate, 2M. Dissolve 472 g Ca(N03)2 • 4H20 In 750
ml distilled water. Dilute to 1 liter with distilled water.
5. Cation exchange resin, Dowex 50WX8, 50-100 mesh, Ma form, or
equivalent. Wash 40 ml resin (H+) with 600 ml 4M NaCl. Wash
all excess NaCl from resin with water and check for chloride with
0.1M AgN03 before using resin.
6. Ethanol, 95 percent reagent.
7. Ethylenedlamlne tetraacetlc add dlsodium salt, Na2EDTA 6
percent. Dissolve 66.6 g Na2EDTA In 900 ml distilled water and
dilute to 1 liter with distilled water.
8. Ethylenedlamlne tetraacetlc add d1 sodium salt, Na2EDTA 2
percent. Dissolve 22.2 g Na2EDTA in 900 ml distilled water and
dilute to 1 liter with distilled water.
9. Hydrochloric acid, 12M. Reagent grade HC1.
10. Hydrochloric acid, 6M. Dilute 500 ml of the reagent grade HC1 to
1 liter with distilled water.
11. Hydrochloric acid, 1.5M. Dilute 125 ml of the reagent grade HC1
to 1 liter with distilled water.
12. Nitric acid, 191. Reagent grade HN03>
13. Nitric acid, 6M. Dilute 375 ml of the reagent grade HN03 to 1
liter with distilled water.
14. Silver nitrate, 0.1M. Dissolve 1.7 g AgN03 reagent in
distilled water. Dilute to 100 ml with distilled water. Store
in brown bottle.
15. Sodium acetate, buffered pH 4.6. Dissolve 200 g of anhydrous
sodium acetate in 500 ml distilled water. Adjust pH to 4.6 with
acetic acid and dilute to 1 liter with distilled water.
16. Sodium carbonate. Anhydrous reagent powder.
17. Sodium carbonate, 1.5M. Dissolve 159 g of Na2C03 in 900 ml
of distilled water and dilute to 1 liter with distilled water.
18. Sodium chloride, 411. Dissolve 234 g of NaCl in 900 ml of
Sr-01-2
-------
distilled water and dilute to 1 liter with distilled water.
19. Sodium hydroxide. Reagent grade pellets.
20. Strontium carrier, 20. mg Sr+2/ml. Dissolve 48.3 g of
Sr(N03)2 in 900 ml of distilled water. Add 1 ml 16M HN03
reagent and dilute to 1 liter with distilled water.
Procedure
1. Dry the homogenized sample at 110°C to constant weight.
2. Ash the dried sample at 550°C for no less than 72 hours.
3. Place 10 g of ash in a 250 ml nickel crucible. Add 2 ml of
strontium carrier and 1 ml barium carrier to the ash. Add 1 ml
of 2M calcium nitrate solution. See Note 2.
4. Add 50 g of sodium hydroxide pellets, mix and fuse over a blast
burner for 15 minutes or until the sample is a clear red melt.
Begin heating slowly. Gradually increase heating when reaction
subsides. Remove crucible from flame and slowly add 5 g
anhydrous sodium carbonate, swirl to mix, and heat the clear melt
for 20 minutes.
5. Transfer the crucible from the heat to a cold water bath in order
to crack the fusion mixture. Transfer the mixture to a one-liter
beaker and wash the residue into the beaker with distilled water.
6. Add 200 ml hot, distilled water to the beaker and gently boil to
disintegrate the fused mixture. See Note 3.
7. Transfer the sample to a 250 ml centrifuge bottle and centrifuge
for five minutes. Discard supernate.
8. Wash the residue twice with 200 ml aliquots of hot distilled
water, discarding the supernate each time.
9. Dissolve the residue in 20 ml 6M HC1 by gently boiling until the
solution is transparent. Add 100 ml water.
10. If insoluble silica is present, centrifuge, pour off supernate
and save in separate beaker.
11. Wash the residue twice with 100 ml aliquots of distilled water.
Sr-01-3
-------
Centrifuge and add wash water to beaker containing first wash
solution from step 10. Discard residue.
12. Add combined sample to 500 ml of 6 percent disodium EOTA solution
In a 2-liter beaker. Adjust pH to 3.8 with pH meter using
approximately 10 ml 15M NH^OH. See Note 4.
13. Stir vigorously for 75 minutes using a magnetic stlrrer to
precipitate the magnesium salt of EDTA.
14. Filter off any Mg EDTA and adjust filtrate to pH 4.6 (pH meter)
with approximately 2 ml of 15M NH4OH. Add 20 ml of sodium
acetate buffer solution, pH 4.6 and readjust solution to pH 4.6
(pH meter) with approximately 4 ml of 15M NH4OH. Dilute to 1
liter.
15. Transfer solution to column reservoir and let flow through the
cation resin column at a flow rate of 20 ml per minute. Stop
flow when just enough solution remains to cover top of resin In
column.
16. Adjust pH of 600 ml, 2 percent Na2EDTA to 5.1 with 6M NH4OH.
Add to column reservoir and let flow through column at 20
ml/minute. Record time at end of elutlon as beginning of
yttr1um-90 Ingrowth.
17. Wash column with 200 ml water at a flow rate of 20 ml/minute.
Discard all effluents.
18. Place 460 ml 1.5M HC1 In reservoir and elute at a flow rate of 8
ml/minute. Discard first 60 ml of effluent. Collect the next
400 ml, which contains the strontium fraction.
19. Add 200 ml 15M NH4OH to the effluent containing the strontium
fraction and stir with a magnetic stlrrer. Slowly add 10 ml
1.5M Na2C03 solution and stir vigorously for an additional
30 minutes.
20. Collect the strontium carbonate precipitate on a tared membrane
filter. Wash with three 10 ml aliquots each of water and
ethanol. Transfer to a planchet and allow sample to dry one hour
in a desiccator.
Sr-01-4
-------
21. Weigh the precipitate and count the radiostrontium in a
low-background beta counter. Repeat the count In six to seven
days and calculate the stront1um-90 from the difference in the
counts.
22. Regenerate the resin column by flowing 600 ml 4h1 NaCl over the
column, followed by 1 liter distilled water.
Calculations
Calculate the concentration, Z, of strontlum-90 1n plcocuries per
liter or plcocuries per gram ash as follows:
Z = [A] [B] - [C] [D] X 1
[1+(EHF>] (A) - [1 +(G)(H)] (C) (2.22)(I)(J)(K)(L)
where
oq
A = decay factor of Sr from the time of collection to the
time of the first count,
B = net counts per minute of total strontium on second count,
OQ
C = decay factor of Sr from the time of collection to the
time of the second count,
D = net counts per minute of total strontium on first count,
on on
E = ratio of the Y/ Sr counting efficiencies on the
second count,
F = 90Y ingrowth factor from the time of separation to the
time of the second count,
ratio
count,
ing row
first count,
counting eff
J = chemical yield of strontium,
= ratio of the 90Y/90Sr counting efficiencies on the first
90
= ingrowth factor of Y from time of separation to time of
90
I = counting efficiency of Sr first count,
Sr-01-5
-------
90
K = absorption factor for Sr, and
L = sample volume in liters or sample weight in grams.
Calculate the concentration, Z, of strontium-89 in picocuries per
liter or picocuries per gram ash as follows:
Z = (D) - [1 * (H)(G)] (M) X 1 _
A (2.22)(0)(J)(H)(L)
where
D = net counts per minute of total strontium on the first count,
90
H = ''"Y ingrowth factor from separation to first count,
90 90
G = ratio of the Y/ Sr counting efficiencies on the first
count,
90 90
M = net cpm of Sr (first fraction of Sr calculation),
on
A = decay factor of Sr from time of collection to the time
of first count,
89
0 = absorption factor for Sr,
J = chemical yield of strontium,
89
N = counting efficiency of Sr, and
L = sample volume in liters or sample weight in grams.
Calculate the lower limit of detection (LID) in picocuries per gram
as follows:
LLD = 4'66 V CBT
(2.22)(E)(R)(T)(W)
where
CB = background count rate,
T = counting time (same for sample and background),
Sr-01-6
-------
E = beta counter efficiency,
R = fractional chemical yield,
W = sample size (grams), and
2.22 = dpm per pC1.
This LLD calculation is valid If the sample counting time Is the same
as the background counting time.
Notes
1. Metricel is a trademark of Gelman Sciences, Inc., Ann Arbor, Michigan.
2. For the following types of sample ash, use the weights listed Instead
of the 10 g in step 3 of this procedure:
Fish ash, 3 g.
Bone ash, 3 g. Do not add Ca(N03)2 to bone.
Vegetation ash, 5 g.
For 3 g of ash use 20 g of NaOH pellets and 2 g Na2C03 for
fusion. For 5 g of ash use 25 g of NaOH pellets and 3 g Na2C03
for fusion.
3. If the fusion mass is not easily removed from the crucible, it may be
necessary to add the crucible to the boiling water to dislodge the
mass.
4. If precipitation occurs, increase pH with 6M NH4OH until clear then
bring pH back to 3.8 with 6M HC1.
References
1. Porter, C.R., Procedures for Determination of Stable Elements and
Radionuclldes in Environmental Samples, Public Health Service
Publication No. 999-RH-10 (1965).
2. Velten, R.J., "Resolution of Sr-89 and Sr-90 1n Environmental Media by
an Instrumental Technique," Nuclear Instruments and Methods, 42, 169
(1966).
Sr-01-7
-------
3. Porter, C.R., Kahn, B., Carter, M.W., Rehnberg, G.L., and Pepper,
E.N., "Determination of Radiostrontlum in Food and Other
Environmental Samples," Environmental Science and Technology, 1,,
745-750 (1967).
Sr-01-8
-------
RADIOCHEMICAL DETERMINATION OF RADIOSTRONTIUM IN MILK
Principle
Barium and strontium carriers are added to the milk sample. Calcium
in the milk is complexed with EDTA to prevent loading the cation exchange
resin through which the milk 1s passed. A one liter sample of milk is
passed through 85 ml of resin at a rate of up to 100 ml per minute.
Strontium is eluted from the resin and precipitated. Strontium-89 and
strontium-90 are radioassayed separately by measuring the ingrowth of
yttrium-90.
Special Apparatus
1. Ion exchange column, 3.2 cm Internal diameter, 15 cm in length.
2. Graduated separatory funnel as reservoir for column, 1 liter
capacity.
3. Netricel DM-800 membrane filters or equivalent, 25 mm diameter,
0.8 micrometer pore size. See Note 1.
4. Stainless steel planchets, 5 cm diameter.
5. Suction filter apparatus.
6. Glassware.
7. Desiccator.
8. Floor centrifuge.
9. pH meter.
Reagents
1. Acetic acid, glacial. Reagent grade HCgH^Og.
2. Ammonium acetate buffer, pH5. Dissolve 153 g ammonium acetate in
700 ml distilled water. Adjust pH to 5 with glacial acetic
acid. Dilute to 1 liter with distilled water.
3. Ammonium acetate buffer, pH 5.2. Dissolve 153 g ammonium acetate
in 700 ml distilled water. Adjust pH to 5.2 with glacial acetic
acid. Dilute to 1 liter with distilled water.
Sr-02-1
-------
4. Ammonium hydroxide, 15M. Reagent grade NH4OH.
5. Barium carrier, 20 mg Ba+2/ml. Dissolve 38.1 g Ba(N03)2 in
900 ml distilled water. Add 1 ml 16M HN03 and dilute to 1
liter with distilled water.
6. Cation exchange resin, Dowex 50W-X8, 50-100 mesh, Na* form, or
equivalent. Wash 85 ml resin (H*) with 600 ml 4M NaCl to
convert resin to Na form. Wash all excess NaCl from resin
with water and check for chloride with 0.1M AgN03 before using
resin.
7. Ethanol, 95 percent reagent.
8. Ethylenediamine tertraacetic acid complexing solution. Dissolve
216 g Na2EDTA in 2500 ml distilled water. Add 20 ml each of
strontium and barium carriers (20 rug/ml). Then add 200 ml
ammonium acetate buffer, pH 5.2 and adjust pH to 5.65 with 15M
ammonium hydroxide. Dilute to 3 liters.
9. Ethylenediamine tetraacetic acid disodium salt, Na2EDTA, 3
percent. Dissolve 33.3 g of Na2EDTA in 900 ml distilled water
and dilute to 1 liter with distilled water.
10. Nitric acid, 16M. Reagent grade HN03.
11. Nitric acid 1M. Dilute 62 ml HN03 to 1 liter with distilled
water.
12. Silver nitrate, 0.1F1. Dissolve 1.7 g AgN03 reagent in
distilled water. Dilute to 100 ml with distilled water. Store
in brown bottle.
13. Sodium carbonate, 1.5M. Dissolve 159 g of Na2C03 in 900 ml
distilled water and dilute to 1 liter with distilled water.
14. Sodium chloride, 1.5M. Dissolve 87.7 g NaCl in 900 ml distilled
water and dilute to 1 liter with distilled water.
15. Sodium chloride, 4M. Dissolve 234 g NaCl in 900 ml distilled
water and dilute to 1 liter with distilled water.
16. Sodium chromate, 0.25M. Dissolve 40.5 g Na2Cr04 in 900 ml
distilled water and dilute to 1 liter with distilled water.
Sr-02-2
-------
17. Sodium hydroxide, 6M. Dissolve 240 g HaOH in 900 ml distilled
water and dilute to 1 liter with distilled water.
18. Strontium carrier, 20 mg Sr*2/ml. Dissolve 48.3 g Sr(N03)2
in 900 ml distilled water. Add 1 ml 16M HN03 and dilute to 1
liter with distilled water.
Procedure
1. Filter a 1 liter sample of milk through cheesecloth and add 300
ml of the complexing solution to the milk sample and mix well.
2. Adjust milk mixture to pH 5.2 with 15M NH4OH using pH meter.
3. Pour the milk sample into a graduated separatory funnel and
attach to the top of the ion exchange column.
4. Open stopcocks on reservoir and column and allow the milk to flow
through the resin by gravity that will not exceed 100 ml/min.
5. After all the milk has passed through the column, rinse sides at
top of column with 50 ml water and wash with approximately 200 ml
water until the effluent runs clear. Do not let column run dry.
6. Add 800 ml of 3 percent Na^EDTA (pH 5.2) to the reservoir and
elute through the column at 20 ml per minute. Record the time of
EDTA elution as the beginning of yttrium-90 ingrowth.
7. Add 200 ml distilled water to reservoir and run through column at
20 ml per minute.
8. Add 200 ml of 1.5M NaCl to reservoir and pass solution through
the column at a flow rate of 10 ml per minute.
9. Add 1000 ml 4f1 NaCl to reservoir and pass solution through the
column at a flow rate of 20 ml per minute. Collect the first 400
ml of eluate, which contains strontium and barium, and allow the
remaining 600 ml NaCl to pass through the column to regenerate
the resin.
10. Wash all excess NaCl from resin with distilled water and check
eluate for chloride with O.M AgN03 before reusing resin.
Sr-02-3
-------
11. Add 1 ml of W NaOH to the 400 ml of eluate from step 9. Stir
and slowly add 10 ml of 1.5M Na2C03 to precipitate SrCO.j.
Continue vigorous stirring for 30 minutes using a magnetic
stirrer.
12. Transfer one half of the contents to a 250 ml centrifuge bottle.
Centrifuge at 2000 rpm for 10 minutes and carefully pour off and
discard supernate.
13. Add the remaining solution to the precipitate in the 250 ml
centrifuge bottle. Centrifuge at 2000 rpm for 10 minutes. Pour
off and discard supernate.
14. Place the centrifuge bottle containing the precipitate in a hot
water bath held at 70°C.
15. Add 5 ml 1M_ HN03 to centrifuge bottle to dissolve precipitate.
Transfer solution to a 50 ml centrifuge tube.
16. Wash the 250 ml centrifuge bottle with 5 ml of ammonium acetate
buffer, pH5, and add the wash to the dissolved precipitate in the
50 ml centrifuge tube.
17. Heat the 50 ml centrifuge tube at 70°C in a water bath with
stirring and slowly add 1 ml of 0.25M^ Na2Cr04 to precipitate
barium chromate.
18. Cool tube from step 17 in ice bath, centrifuge and decant
supernate containing strontium into another 50 ml centrifuge
tube. Discard barium chromate precipitate.
19. Add 2 ml 15M NH4OH to the supernate with stirring and
precipitate strontium carbonate by adding 2 ml 1.5J1 Na2C03.
20. Stir precipitate for ten minutes. Centrifuge for five minutes.
Pour off and discard supernate. .
21. Add 20 ml of distilled water to tube to wash the precipitate.
Centrifuge and discard wash solution. Take up precipitate in 10
ml distilled water. Gently swirl to break up precipitate.
22. Filter sample through a tared membrane filter. Wash with three
10 ml aliquots each of water and ethanol.
Sr-02-4
-------
23. Dry sample for one hour in a desiccator, weigh and count in a low
background beta counter.
24. Recount sample in six to seven days.
Calculations
Calculate the concentration, Z, of strontium-90 in picocuries per
liter or picocuris per gram ash as follows:
Z = [A] [B] - [C] [D]
[1+(E)(F)3 (A) - [1 *(6)(H)] (C) (2.22)(I)(J)(K)(L)
where
89
A = decay factor of Sr from the time of collection to the
time of the first count,
B = net counts per minute of total strontium on second count,
on
C = decay factor of Sr from the time of collection to the
time of the second count,
D = net counts per minute of total strontium on first count,
on on
E = ratio of the *uY/3USr counting efficiencies on the
second count,
QQ
F = Y ingrowth factor from the time of separation to the
time of the second count,
ratio
count,
ingrow
first count,
= ratio of the 90Y/90Sr counting efficiencies on the first
on
ingrowth factor of Y from time of separation to time of
90
I = counting efficiency of Sr first count,
J = chemical yield of strontium,
K = absorption factor for Sr, and
L = sample volume in liters or sample weight in grams.
Sr-02-5
-------
Calculate the concentration, Z, of stronti'um-89 In picocuries per
liter or picocuries per gram ash as follows:
where
Z = (D) - [1 + (H) (G)] (M) X
1
(2.22)(0)(J)(N){L)
0
H
G
M
A
0
J
N
L
net counts per minute of total strontium on the first count,
90
Y ingrowth factor from separation to first count,
90 90
ratio of the Y/ Sr counting efficiencies on the first
count,
net cpm of 90Sr (determined by 90Sr calculation),
89
decay factor of Sr from time of collection to the time of
first count,
89
absorption factor for Sr,
chemical yield of strontium,
89
counting efficiency of Sr, and
sample volume in liters or sample weight in grams.
Calculate the lower limit of detection (LLD) in picocuries per gram as
follows:
where
LLD =
4.66-
(2.22)(E)(R)(T)(V)
B
T
E
R
V
2.22
background count rate,
counting time (same for sample and background),
beta counter efficiency,
fractional chemical yield,
sample size (liters), and
dpm per pCi,
Sr-02-6
-------
This LLD calculation is valid if the sample counting time is the same
as the background counting time.
Notes
1. Metrical is a trademark of Gelman Sciences Inc., Ann Arbor, Michigan.
References
1. Porter, C.R., Cahill, D., Schneider, R., Robbins, P., Perry, W., and
Kahn, B., "Determination of Stront1um-90 in Milk by an Ion Exchange
Method," Analytical Chemistry, 33, 1306-1308 (1961).
2. Porter, C.R. and Kahn, B., "Improved Determination of Strontium-90 in
Milk by an Ion Exchange Method," Analytical Chemistry, 36, 676-8,
(1964).
3. Porter, C., Carter, M. W., Kahn, B. and Pepper, E. W., Rapid Field
Method for the Collection of RadionucTides in Milk Proceedings of the
First International Congress of Radiation Protection, Rome, Italy
September 5-10, 1966.
4. Velten, R. J., "Resolution of Sr-89 and Sr-90 in Environmental Media
by an Instrumental Technique," Nuclear Instruments and Methods, 42,
1969 (1966).
5. Rehnberg, G.L., Strong, A.B., Porter, C.R., and Carter, M.W., "Levels
of Stable Strontium in Milk and the Total Diet," Environmental Science
and Technology, 3, 171-173 (1969).
Sr-02-7
-------
RADIOCHEMICAL DETERMINATION OF STROMTIUH-90 IN URINE
Principle
Yttrium carrier in a citric acid solution is added to the urine
sample. The sample is passed over an anion exchange resin after adjusting
the pH to 4.5. Yttrium is eluted from the resin column with HCl and is
precipitated as yttrium oxalate. The yttrium-90 1s radioassayed on a
low-background beta counter and the activity of strontiuro-90 is calculated.
Special Apparatus
1. Centrifuge.
2. Ion exchange column, 3.8 cm dia., 18 cm length.
3. pN meter.
4. Separator/ funnel, 1 liter capacity.
5. Suction filter apparatus for 25 tran membrane filter.
6. Metricel DM 800 filter membranes or equivalent, 25 RIBI diameter,
0.8 micrometer pore size. See Mote 1.
Reagents
1. Ammonium hydroxide, 15M, reagent grade HH^OH.
2. Anion exchange resin. Dowex 1X8 or equivalent 50-100 mesh,
chloride form.
3. Citric acid, 1M, pH 4.5. Dissolve 210 g of reagent grade citric
acid monohydrate in 500 ml distilled water. Adjust solution to
pH 4.5 with 12M MaOH using a pH meter. Di7ute the solution to 1
liter.
4. Ethanol, 95 percent reagent.
5. Hydrochloric acid, 12M, 37 percent HCl reagent.
6. Hydrochloric acid, 3M. Dilute 250 ml of the 37 percent reagent
grade HCl to 1 liter with distilled water.
7. MerthfoJate solution, 0,1 percent. Dissolve 1 g sodium
merthiolate in 1 liter distilled water.
Sr-03-1
-------
8. Oxalic acid, 1M. Dissolve 126 g of C2H204 • 2H20 In 900
ml of distilled water and dilute to 1 liter.
9. Sodium hydroxide, 12M. Dissolve 480 g reagent grade MaOH in
400 ml distilled water. When cool dilute to 1 liter.
10. Yttrium carrier, 10 mg Y+3/ml. Heat, but avoid boiling,
12.7 g Y203 in 50 ml 16M HN03 until dissolved. Transfer
to a 1 liter volumetric flask and dilute to 900 ml. Adjust to
pH2 with 15M NH4OH and dilute to 1 liter.
Procedure
1. Prior to sample collection, add 80 ml of merthiolate to one
gallon sample container. At end of collection period (T^)
store sample for 10-14 days for yttrlum-90 ingrowth.
2. Measure a 1-liter aliquot into a beaker. Add 1 ml of yttrium
carrier to 5 ml of 1M citric acid in a tube. Swirl to mix and
transfer quantitatively to the urine in the beaker with distilled
water. Stir well.
3. Adjust to pH 4.5-5.0 with NaOH using pH meter. Filter through
Whatman number 42 filter paper in a 20-cm diameter Buchner funnel
with vacuum. Discard filter.
4. Transfer filtrate to a 1-liter separator/ funnel and attach to
the anion resin column, which 1s filled with distilled water.
5. Record the time (T2). Allow sample to flow through the resin
at 10 ml per minute. Discard the effluent.
6. Add 500 ml of distilled water to the separatory funnel and resume
flow at 10 ml per minute. Stop flow when just enough water
remains in the column to cover the resin.
7. Add 500 ml 3f1 HC1 to the separatory funnel and let flow at 2-3 ml
per minute. Discard effluent until pH drops to 2 (check with pH
paper). Collect the next 65 ml of eluate in a 250 ml centrifuge
bottle.
8. Allow remaining acid to pass through the column to recharge the
Sr-03-2
-------
resin. Stir the resin bed well and wash with 500 ml distilled
H20.
9. Centrifuge the 65 ml of eluate and transfer supernate to another
centrifuge bottle. Discard any precipitate.
10. Add 2 ml of 2h1 oxalic acid to the eluate and adjust to pH 1.6
with 15M HH4OH (use pH meter). Heat in a hot water bath for 15
minutes; then allow to cool to room temperature.
11. Centrifuge and discard the supernate. Wash the precipitate with
10 ml distilled water, centrifuge, and discard supernate.
12. Weigh a stainless steel planchet and 2.5-cm diameter membrane
filter. Place filter in filtering apparatus.
13. Transfer precipitate to filter membrane with distilled water.
Wash with 15 ml distilled water and 30 ml of ethanol. Continue
suction for two minutes.
14. Transfer the filter with precipitate to the stainless steel
planchet and weigh the sample to determine yttrium recovery.
15. Count in a low-background beta counter and record the time
(T3). Count again after three days to confirm absence of
contamination of yttrium-90 by other radionuclides.
Calculations
Calculate the concentration, Z, of strontium-90 in picocuries per 24
hour sample as follows:
(A)(B)(EHF)(V2)
where
C, = sample gross counts per minute,
d, = counter background counts per minute,
o
V. = volume of 24-hour sample in liters,
Sr-03-3
-------
A = correction factor for Y decay (e~xt) where t (hours)
is the time from beginning of analysis to time of counting
(T3-T2),
90 it
B = correction factor for ingrowth of Y (l-e~AU) where t
(hours) is the time from the end of sample collection period
to time of beginning of analysis (Tg-Tj),
E = counter efficiency for Y in cpm/pCi,
F = yttrium oxalate recovery, and
Y2 = aliquot analyzed (liters).
Calculate the lower limit of detection (LLD) for strontium-90 in
picocuries per 24-hour sample as follows:
LLD =
(A)(B)(E)(F)(Y2)(T)
where
CB = counter background counts per minute,
V, = volume of 24-hour sample in liters,
A = correction factor for 90Y decay (e~xt) where t (hours)
is'the time from begining of analysis to time of counting,
B = correction factor for ingrowth of 90Y (l-e"xt) where t
(hours) is the time from the end of sample collection period
to time of beginning of analysis,
90
E = counter efficiency for Y in cpm/pCi,
F = yttrium oxalate recovery, and
V2 = aliquot analyzed (liters).
This LLD is valid only of the background counting time is equal to
the sample counting time.
Sr-03-4
-------
Notes
1. Metrfcel is a trademark of Gel man Sciences Inc., Ann Arbor, MI.
References
1. Cahill, D.F., and Lindsey, G.X.. "Determination of Strontium-90 in
Urine by Anion Exchange," Analytical Chemistry, 38, 639 (1966).
Sr-03-5
-------
RADIOCHEMICAL DETERMINATION OF RADIOSTRONTIUM IN WATER.
SEA WATER AND OTHER AQUEOUS MEDIA
Principle
Barium, calcium and strontium carriers are added to the sample.
Magnesium 1s precipitated and removed from the sample at pH 3.8. Barium
and strontium are adsorbed on a cation exchange resin while calcium Is
eluted. Barium and strontium are selectively eluted and strontium Is
precipitated. Strontlum-89 and strontium-90 are radioassayed separately
by measuring Ingrowth of yttrlum-90. Urine samples are analyzed for
strontium using a different procedure. See Strontlum-90 In Urine.
Special Apparatus
1. Graduated separately funnel as reservoir for column, 1 liter
capacity.
2. Ion exchange column, 2.5 cm Internal diameter, 18 cm long.
3. Metrice! DM 800 membrane filters or equivalent, 25 mm diameter,
0.8 micrometer pore size. See Note 1.
4. Stainless steel planchets, 5 cm diameter.
5. Suction filter apparatus.
6. Glassware.
7. Whatman 2V fluted filter paper or equivalent.
8. Magnetic stirrer and stirring bars.
Reagents
1. Acetic acid, glacial. Reagent grade HC2H302.
2. Ammmonlum hydroxide, 15M. Reagent grade NH^OH.
3. Ammonium hydroxide, 6f1. Dilute 400 ml NH4OH reagent to 1 liter
with distilled water.
+2
4. Barium carrier, 20 mg Ba /ml. Dissolve 38.2 g Ba(NO,)2 in
900 ml distilled water. Add 1 ml 16M HN03 and dilute to 1
liter with distilled water.
Sr-04-1
-------
+2
5. Barium carrier, 5 mg Ba /ml. Dissolve 9.5 g Ba(N03)2 in
900 ml distilled water. Add 1 ml 16M HN03 and dilute to 1
liter with distilled water.
6. Calcium nitrate, 2M. Dissolve 47.2 g Ca(N03)2»4H20 in
distilled water and dilute to 100 ml with distilled water.
7. Cation exchange resin. Dowex 50UX8, 50-100 mesh, Na form, 40
ml per column. Wash resin (H+) with 600 ml 4M NaCl to convert
resin to Na form. Wash all excess NaCl from resin with water
and check effluent wash water for chloride with 0.1M AgN03
before using resin.
8. Ethanol, 95 percent reagent.
9. Ethylenediamine tetraacetic acid, disodium salt. Na2EDTA
reagent powder.
10. Ethylenediamine tetraacetic acid, disodium salt, Ma2EDTA, 3
percent. Dissolve 33.3 g of Na2 EDTA in 900 ml distilled water
and dilute to 1 liter with distilled water.
11. Ethylenediamine tetraacetic acid, d1sodium salt, Na2EDTA, 2
percent. Dissolve 22.2 g of Na2 EDTA in 900 ml distilled water
and dilute to 1 liter with distilled water.
12. Hydrochloric acid, 12M. Reagent grade HC1.
13. Hydrochloric acid, 6M. Dilute 500 ml reagent grade HC1 to 1
liter with distilled water.
14. Hydrochloric acid, 1.5M. Dilute 125 ml reagent grade HC1 to 1
liter with distilled water.
15. Nitric acid, 16^. Reagent grade HN03.
16. Silver nitrate, 0.1M. Dissolve 1.7g AgN03 reagent in distilled
water. Add 1 ml 16M HN03 and dilute to 100 ml with distilled
water. Store in brown bottle.
17. Sodium acetate buffer, pH 4.6. Dissolve 200 g NaC2H302 in
400 ml distilled water. Adjust pH to 4.6 with glacial acetic
acid. Dilute to 1 liter with distilled water.
Sr-04-2
-------
18. Sodium carbonate, 1.5M. Dissolve 159 g of Na2C03 in 900 ml
distilled water and dilute to 1 liter with distilled water.
19. Sodium chloride, 4M. Dissolve 234 g of NaCl in 900 ml distilled
water and dilute to 1 liter with distilled water.
20. Sodium hydroxide, 6M. Dissolve 240 g of NaOH in 900 ml distilled
water and dilute to 1 liter with distilled water.
21. Strontium carrier, 20 mg Sr*2/ml. Dissolve 48.3 g Sr(N03)2
in 900 ml water. Add 1 ml 16M HN03 and dilute to 1 liter with
distilled water.
Procedure
1. Acidify a 3.78 liter (one gallon) sample with 2 ml of 6M HC1.
2. Mix thoroughly and filter through a fluted filter paper.
3. Place a one liter aliquot of the sample In a 2 liter beaker.
4. Add 2 ml of strontium carrier, 1 ml of barium carrier and 2 ml of
calcium nitrate solution. Stir well.
5. For fresh water samples, proceed to step 6; for sea water
samples, pretreat as directed in steps 5 a through 5 g.
(a) Heat sample to near boiling on a hot plate.
(b) Adjust pH to 10 with approximately 10 ml of 6M NaOH.
(c) Add 30 ml of 1.5M Na2C03 with stirring.
(d) Continue heating until precipitate settles to the bottom of
the beaker.
(e) Remove sample from the hot plate and allow solution to cool
to room temperature.
(f) Decant supernate. Transfer precipitate to a 250 ml
centrifuge bottle with distilled water. Centrifuge and
discard supernate.
(g) Dissolve precipitate in 30 ml of 6M HC1 and add to 500 ml of
3 percent disodium EDTA. Go to step 7.
6. Add 33.3 g disodium EDTA powder to the fresh water sample from
step 5 and stir until dissolution of the powder is complete.
Sr-04-3
-------
7. Adjust sample to pH 3.8 with pH meter using 15M NH4OH or 6M HC1.
8. Stir vigorously for 75 minutes using a magnetic stlrrer to
precipitate the magnesium salt of EDTA.
9. Filter, If necessary, and adjust filtrate to pH 4.6 with
approximately 2 ml of 15M NH4OH.
10. Add 20 ml of sodium acetate buffer solution, pH 4.6 and readjust
to pH 4.6 with approximately 4 ml of 15M NH4OH.
11. Pass the 1-Hter sample through resin column at 20 ml per
minute. Stop the flow when enough solution remains to cover
resin.
12. Adjust 600 ml of the 2 percent disodium EDTA to pH 5.1 with 6M
NH4OH.
13. Place the 2 percent disodium EDTA from step 12 In the column
reservoir and let flow through the resin column at 20 ml per
minute.
14. Record time at end of elutlon In step 13 as beginning of
yttrium-90 Ingrowth.
15. Wash the column with 200 ml water at a flow rate of 20 ml per
minute and discard all effluents.
16. Place 460 ml 1.5J1 HC1 in reservoir and elute at a flow rate of 8
ml per minute, discarding the first 60 ml of effluent.
17. Collect the next 400 ml, which contain the strontium fraction.
18. Add 200 ml 15*1 NH^OH to the strontium fraction from step 17 and
stir with a magnetic stirrer. Slowly add 10 ml 1.5M Na2C03
solution and stir vigorously for 30 minutes.
19. Collect the strontium carbonate precipitated in step 18 on a
weighed membrane filter. Wash with three 10 ml aliquots each of
water and ethanol. Transfer to a planchet and dry for 1 hour in
a desiccator.
20. Weigh the strontium carbonate to the nearest 0.1 mg and count the
radiostrontium in a low-background beta counter.
21. Count the sample again after six to seven days and calculate the
strontium-90.
Sr-04-4
-------
22. Regenerate the cation exchange resin by elutlng 600 ml of 4P1
NaCl through the column at 8 ml/minute. Wash the resin with
water until all chlorides are removed by checking with a silver
nitrate solution.
Calculations
Calculate the concentration, Z, of strontium-90 in picocuries per
liter or picocuries per gram ash as follows:
Z = [A] [B] - [C] [D] X 1
C1+(E)(F)] (A) - [1 +(G)(H)] (C) (2.22)(I)(J)(K)(L)
where
89
A = decay factor of Sr from the time of collection to the
time of the first count,
B = net counts per minute of total strontium on second count,
QQ
C = decay factor of Sr from the time of collection to the
time of the second count,
D = net counts per minute of total strontium on first count,
on on
E = ratio of the *uY/*uSr counting efficiencies on the last
co.unt,
90
F = Y ingrowth factor from the time of separation to the
time of the last count,
ratio
count,
ingrow
first count,
counting eff
J = chemical yield of strontium,
90
K = absorption factor for Sr,
L = sample volume in liters or sample weight in grams.
on on
= ratio of the ""Y/^Sr counting efficiencies on the first
90
ingrowth factor of Y from time of separation to time of
on
I = counting efficiency of Sr first count,
>nt1
90
K = absorption factor for Sr, and
Sr-04-5
-------
Calculate the concentration, Z, of strontium-89 In picocurles per
liter or picocurles per gram ash as follows:
Z • (D) - [1 * (H)(G)] (M) X 1
A (2.22)(0)(J)(N)(L)
where
D = net counts per minute of total strontium on the first count,
90
H = Y ingrowth factor from separation to first count,
on on
G = ratio of the 3UY/*uSr counting efficiencies on the first
count,
M = net cpm of Sr (first fraction of Sr calculation),
89
A = decay factor of Sr from time of collection to the time
of first count,
on
0 = absorption factor for °'Sr,
J = chemical yield of strontium,
on
N = counting efficiency of Sr, and
L = sample volume In liters or sample weight in grams.
Calculate the lower limit of detection (LLD) in picocuries per liter
as follows:
LLD = 4'66
(2.22)(E)(R)(T)(V)
where
CB = background count rate,
T = counting time (same for sample and background),
2.22 = dpm per pCI,
E = beta counter efficiency,
R = fractional chemical yield, and
V = sample size (liters).
Sr-04-6
-------
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. Metricel is a trademark of Gelman Sciences, Inc., Ann Arbor, Michigan.
References
1. Porter, C.R., Procedures for Determination of Stable Elements and
Radionuclides in Environmental Samples, Public Health Service
Publication No. 999-RH-10 (1965).
2. Velten, R.J., "Resolution of Sr-89 and Sr-90 in Environmental Media by
an Instrumental Technique," Nuclear Instruments and Methods, 42yU69
(1966).
3. Porter, C.R., Kahn, B., Carter, M.W., Rehnberg, G.I., and Pepper,
E.W., "Determination of Radiostrontium in Food and Other Environmental
Samples," Environmental Science and Technology, 1, 745-750 (1967).
Sr-04-7
-------
PREPARATION OF THORIUM-234 TRACER SOLUTION
Principle
Uranium Is adsorbed on an anlon exchange resin in strong HC1. The
thorium-234 decay product is periodically eluted with strong HC1. The
eluted thorium is further purified by passing the eluted solution through
a second column of anion exchange resin. The final thorium-234 solution
is radioassayed by coprecipitation with lanthanum as fluoride and beta
counted. The solution is also checked for uranium contamination by
coprecipitation for uranium with lanthanum as fluoride. The coprecipitate
is radioassayed by alpha spectroscopy.
Special Apparatus
1. Ion exchange columns, 5 cm internal diameter, 15 cm length; 2.5 cm
internal diameter, 14 cm length.
2. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore size
or equivalent. See Note 1.
3. Planchets, stainless steel, 32 mm diameter.
4. Separatory funnels, 250 ml capacity as reservoirs for the ion
exchange columns.
5. Suction filter apparatus for 25 mm membrane.
6. Plastic graduated cylinder, 100 ml volume.
7. Alpha spectrometric system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier detectors,
vacuum pump and chamber.
Reagents
1. Anion exchange resin. Dowex 1X8, 100-200 mesh, chloride form.
2. Ethanol, 95 percent reagent.
3. Hydrochloric acid, 12M, 37 percent HC1 reagent.
4. Hydrochloric acid, 1M. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
Th-01-1
-------
5. Hydrofluoric add, 29M, 48 percent HF reagent.
6. Hydrofluoric acid, 3M. Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic
graduated cylinder and storage bottle.
7. Lanthanum carrier, 0.1 mg La /ml. Dissolve 0.0779 g high
purity La(N03)3* 6H20 per 250 ml 1M HC1.
8. Titanium trichloride, 20 percent reagent grade.
9. Titanium trichloride, 0.4 percent. Dilute 1 ml of the 20
percent T1C13 to 50 ml with 1 M HC1. Prepare fresh dally.
10. Uranyl acetate or other uranium salt. Reagent grade crystals.
Procedure
1. Slurry the anion exchange resin with distilled water in a beaker
and fill both columns to within 2 cm from the top of the column.
2. Place the reservoirs on top of the columns and wash the resin by
passing 200 ml water through the columns. Always maintain a
level of liquid above the top of the resin bed.
3. Pass 300 ml of 12M HC1 through the larger column at the rate of
approximately 5 ml per minute.
4. Dissolve the uranium salt in 300 ml of 12M HC1 and pass this
solution through the larger column.
5. Pass 300 ml 12M HC1 through the larger column following the
uranium solution.
6. Discard the eluate and record the date the acid was passed
through the resin.
7. In approximately 14 days, pass 300 ml 12M HC1 through the column
with the adsorbed uranium at a rate of 3 ml/minute . Collect the
eluate containing the thorium-234. See Note 2.
8. Pass 200 ml 12M HC1 through the smaller column at a rate of 5
ml/minute. Discard the eluate.
9. Pass the eluate from the larger column (step 7) through the
second column at a rate of 3 ml/minute.
Th-01-2
-------
10. Wash the second column with 100 ml 12M HC1, collecting the total
eluate.
11. Evaporate the total acid solution just to dry ness.
12. Dissolve in 250 ml 1M HC1 and filter into a storage bottle.
13. Remove at least four 1 ml aliquots of the thorium-234 tracer
solution, transfer to 100 ml beakers and evaporate to dryness.
14. Add 15 ml Ifl HC1 to the residue in each beaker and warm to
approximately 50°C.
15. Add 1 ml of lanthanum carrier and 5 ml of 3N HF to each sample.
Mix well and set aside for 30 minutes.
16. Using suction, filter coprecipitated samples through filter
membranes.
17. Rinse each sample beaker with 10 ml water and add to filter
funnel. Rinse each beaker with 10 ml ethanol and add to funnel.
18. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
19. Mount individual membrane carefully on 32 mm planchet using
double stick tape.
20. Count each coprecipitated sample for thorium-234 on a beta
counter.
21. Each batch of thorium-234 coming from the uranium column in step
7 should be checked for uranium contamination by evaporating a 1
ml aliquot and coprecipitating for uranium in the following
manner.
22. Add 15 ml 1M HC1 to the residue from step 21 and warm to
approximately 50°C.
23. Add 1 ml of 0.4 percent TiClj to reduce the uranium.
24. Add 1 ml of the lanthanum carrier and 5 ml of 3M HF. Mix well
and set aside for 30 minutes.
25. Using suction, filter coprecipitated sample through a filter
membrane.
Th-01-3
-------
26. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
27. Remove clamp and top of funnel with suction on. Allow membrane to
dry.
28. Mount membrane carefully on 32 mm planchet using double stick tape.
29. Count sample for 1000 minutes on alpha spectrometer. See Mote 3.
Notes
1. Nuclepore is a trademark of Nuclepore Corp., Pleasanton, CA.
2. The thorium-234 should be removed from the uranium-containing column
every 14 days regardless of need. Longer periods of time between
elutions result in the appearance of small quantities of thorium-230
in the eluate.
3. If uranium is in the tracer solution, it must be removed by further
treatment with anion exchange resin before use.
References
1. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual. 25th
Ed., Environmental Measurement Labatory, U.S. Department of Energy,
New York.
Th-01-4
-------
PREPARATION OF URANIUM-232 TRACER SOLUTION
Principle
Uranium-232 has a half-life of 72 years and decays to thorium-228,
which has a half-life of 1.9 years. In order to prevent contamination of
samples with thorium-228 and its decay products, any stock of uranium-232
must be periodically decontaminated before use. This should be done on an
annual basis.
Uranium-232 is extracted Into tr1isooctylamine (TIOA). The TIOA is
washed with a mixture of HC1 and HF for decontamination. Uranium Is
stripped from the TIOA with dilute nitric acid and wet ashed. Aliquots of
the cleaned uranium tracer are copredpltated with lanthanum flouride and
radioassayed by alpha spectroscopy to determine the specific activity of
the tracer solution.
Special Apparatus
1. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore size
or equivalent. See Note 1.
2. Planchets, stainless steel, 32 mm diameter.
3. Plastic graduated cylinder.
4. Separatory funnels, 1 liter capacity.
5. Suction filter apparatus for 25 mm membrane.
6. Alpha spectrometrie system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier detectors,
vacuum pump and chamber.
Reagents
1. Ascorbic acid, crystalline reagent.
2. Ethanol, 95 percent reagent.
3. Hydrochloric acid, 12 M_. 37 percent HC1 reagent.
4. Hydrochloric acid, 9 M. Dilute 750 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
U-01-1
-------
5. Hydrochloric acid, 3 M/Hydrofluoric acid, 0.1 ^mixture. Dilute
250 ml of the 37 percent reagent grade HC1 and 3.5 ml of the 48
percent reagent grade HF to 1 liter with distilled water. Store
In a plastic bottle.
6. Hydrochloric acid, 1 M. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
7. Hydrofluoric acid, 29 M. 48 percent HF reagent.
8. Hydrofluoric add, 3 M. Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic
graduated cylinder and storage bottle.
9. Hydrogen peroxide, 50 percent reagent grade.
10. Lanthanum carrier, 0.1 mg La /ml. Dissolve 0.0799 g
La(N03)3« 6H20 per 250 ml 1 M HC1.
11. Nitric acid, 16 M. 70 percent HN03 reagent.
12. Nitric acid, 0.1 M. Dilute 6 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
13. Titanium trichloride, 20 percent reagent grade.
14. Titanium trichloride, 0.4 percent. Dilute 1 ml of the 20 percent
T1C13 to 50 ml with distilled water. Prepare fresh daily.
15. Triisooctylamine (TIOA), reagent grade.
16. TIOA solution 1n p-xylene, 10 percent. Dissolve 100 ml of the
triisooctylamlne in p-xylene and dilute to 1 liter with p-xylene.
17. p-Xylene, reagent grade.
Procedure
1. From the specific activity of the uranium-232 stock solution,
determine the size of the aliquot to be used so that when diluted
it will result in a final solution of approximately 1 pCi
232U/ml.
232
2. Evaporate the aliquot of U to dry ness in a beaker.
3. Add 10 ml of 12 M^ HC1 and evaporate to dryness.
4. Add 100 ml 9 M HC1 to the beaker and warm to 50°C.
U-01-2
-------
5. Add 10 drops of 50 percent hydrogen peroxide to the solution.
6. Equilibrate 100 ml of the 10 percent TIOA solution with 50 ml of
warm 9 M HC1 by shaking in a separatory funnel for one minute.
7. Allow the layers to separate and discard the lower aqueous acid
phase.
8. Add the solution from step 5 to the TIOA in the separatory funnel
and shake funnel for two minutes.
9. Allow phases to separate and discard the lower aqueous acid phase,
10. Wash the TIOA solution with 50 ml 9 M HC1 wanned to 50°C. Shake
for one minute and discard lower aqueous acid phase when
separated.
11. Wash the TIOA solution with 75 ml of 3 M HC1/0.1 M HF wanned to
50°C. Shake funnel for two minutes and discard lower acid phase
when separated. Repeat this step.
12. Strip the uranium tracer from the TIOA solution by adding 100 ml
0.1 M HN03 to the separatory funnel and shaking the funnel for
two minutes.
13. Allow phases to separate; withdraw and save lower acid phase.
14. Repeat steps 12 and 13 and combine strip solutions.
15. Place combined strip solutions in clean separatory funnel.
16. Add 100 ml p-xylene to combined strip solution and shake funnel
for one minute.
17. Allow phases to separate cleanly; withdraw lower aqueous acid
layer into a beaker. Discard p-xylene.
18. Evaporate solution from step 17 to dryness. Do not overheat.
19. Add 10 ml 12 M HC1 to residue in beaker and take to dryness. Do
not overheat.
20. Take up solution in 250 ml 1 M HC1 and filter through a filter
membrane using suction.
21. Coprecipitate 1 ml aliquots of the stock solution in step 20 by
adding each aliquot to 15 ml 1 M HC1 in a beaker.
22. Add 50 mg ascorbic acid to each beaker.
U-01-3
-------
23. Add 1 ml 0.4 percent TiClj to reduce uranium.
24. Add 1 ml of lanthanum carrier and 5 ml of 3 M HF. Mix well and
set aside for 30 minutes to precipitate LaF3 carrying uranium.
25. Using suction, filter coprecipitated sample through a filter
membrane.
26. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
27. Remove clamp and top of funnel with suction on. Allow membrane to
dry.
28. Mount membrane carefully on 32 mm planchet using double stick tape.
29. Count sample for 1000 minutes on alpha spectrometer.
Notes
1. Nuclepore is a registered trademark of Nuclepore Corp., Pltfasanton, CA.
References
1. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual, 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
New York.
U-01-4
-------
RADIOCHEMICAL DETERMINATION OF GROSS ALPHA AND GROSS BETA
PARTICLE ACTIVITY IN WATER
The water sample is evaporated onto a stainless steel planchet and
counted for gross activity. This procedure provides a rapid screening
measurement to indicate whether specific analyses are required.
Special Apparatus
1. Conductivity meter.
2. Hot plates.
3. Drying lamps.
4. Stainless steel planchets, 5 cm diameter.
5. Pleated filter paper, 32 nrni diameter.
6. Muffle furnace.
Procedure
If some samples require separating the dissolved solids from the
undissolved solids, acidify with HN03 and—
1. Filter the water sample with pleated filter paper. Dry and ash
filter paper at 500°C for 12 to 24 hours.
2. Determine the dissolved solid content of the filtrate by measuring
the conductivity and determining the solids from Figure 1. This
is to determine the volume to be evaporated. The maximum sample
thickness should be less than 5mg/cm2 (on 20 cm2 area, i.e.
100 rag).
3. Transfer the specific volume of water to a beaker and evaporate to
a small volume on a hot plate. Avoid dryness.
4. Transfer residue from beaker to a tared stainless steel planchet
using a rubber policeman and as little distilled water as possible.
5. Dry under a heat lamp, flame over a burner until dull red, cool,
weigh and store in a desiccator. See Note 1.
6. Count for gross alpha and gross beta particle activity.
7. Repeat steps 4, 5, and 6 for the ash, If necessary.
00-01-1
-------
Calculations
Calculate the concentration, Z, of gross alpha or beta in picocuries
per liter as follows:
CI-CB
(2.22)(A)(V)(F)
where
Cj = sample counts per minute,
CB = background counts per minute,
A = counting efficiency for natural uranium,
V = sample volume (liters),
F = self absorption factor from Table 1 or Table 2 based on dry
sample weight, and
2.22 = dpm per pCi.
Calculate the lower limits of detection (LLD) as follows:
LLD= 4.66V-V
(2.22)(A)(V)(F)(T)
where
CB = background counts per minute,
T = counting time,
A = counting efficiency for natural uranium,
V = sample volume (liters),
F = self-absorption factor from Table 1 or 2 based on sample
weight, and
2.22 = dpm per pCi.
This LLD calculation Is valid If the sample counting time Is equal to
the background counting time.
00-01-2
-------
TABLE 1
Alpha Particle Absorption Factor vs Sample Weight
Sample Weight, mg
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
90
100
110
120
130
140
150
160
Alpha Absorption Factor
1.0
.95
.90
.84
.79
.74
.69
.64
.59
.55
.50
.45
.42
.40
.38
.36
.35
.34
.33
.32
.30
.29
.28
.27
.27
00-01-3
-------
TABLE 2
Beta Particle Absorption Factor vs Sample Weight
*
Sample Weight, mg
less than 40
40
45
50
55
60
65
70
75
80
85
90
95
100
2
For sample thickness, mg/cm ,
weight by 20.
Beta Absorption Factor
1.000
.989
.982
.975
.968
.961
.954
.947
.940
.933
.926
.919
.912
.905
on 5 cm dia. planchet, divide sample
Notes
1. Flaming the planchet will result In the loss of polonium-210, If
present.
00-01-4
-------
References
1. Analysis of RadionucTides In Water. Training Course Manual, U.S.
Department of Health, Education, and Welfare, Public Health Service
(1965).
00-01-5
-------
100.000
Q.
10,000- •
o
O
1.000- •
200
100
500
Volume, mL
Figure 1. Conductivity vs. volume.
00-01-6
-------
-------
RADIOCHEMICAL DETERMINATION OF GROSS ALPHA ACTIVITY IN
DRINKING WATER BY COPRECIPITATION
Principle
An aliquot of drinking water is acidified with H2S04. Barium
carrier is added to precipitate barium sulfate and the sample is digested
while wanning up to 50°C for 30 minutes. Iron carrier is then added.
After 30 minutes the sample is neutralized with dilute NH^OH to
precipitate ferric hydroxide. The sample is filtered and the precipitate
is radioassayed after drying. This procedure precipitates radium and all
alpha and beta emitting actinide elements.
Special Apparatus
1. Drying lamp.
2. Filter membranes, 47 mm dia., 0.45 micrometer pore size.
3. Glassware.
4. Magnetic stirrer and stirring bars.
5. Planchets, stainless steel, 5 cm diameter.
6. Low background internal proportional alpha counter.
Reagents
1. Ammonium hydroxide, 6NL Dilute 400 ml reagent grade NH^OH to 1
liter with distilled water.
+2
2. Barium carrier, 5 mg Ba /ml. Dissolve 4.4 g BaCl2«2H20
in 500 ml distilled water.
3. Bromocresol purple, 0.1 percent. Dissolve 100 mg of the water
soluble reagent in 100 ml distilled water.
4. Iron carrier, 5 mg Fe+3/ml. Dissolve 17.5 g Fe(M03)3 • 9H20
in 200 ml distilled water containing 2 ml 16M HN03.
Dilute to 500 ml.
5. Nitric acid, 16M, 70 percent HN03 reagent.
00-02-1
-------
6. SuIfuric acid, 1M. Dilute 55 ml of the 96 percent reagent grade
H2S04 to 1 liter with distilled water.
Procedure
1. Use a measured aliquot of water sample. If the sample is less
than 500 ml, dilute to 500 ml with distilled water.
2. If the sample used is preserved with acid, neutralize to color
change with 6M^ NH^OH using 1 ml bromocresol purple.
3. Add 20 ml 111 HpSO* and flush the radon from the sample by
boiling for two minutes.
4. Allow the sample to stand for three hours for radon progeny to
decay.
5. Place sample on a magnetic stirrer/heater and add 1 ml barium
carrier.
6. Heat the sample to approximately 50°C with stirring for 30
minutes.
7. Add 1 ml iron carrier and 1 ml bromocresol purple reagent.
8. Continue stirring and add 6M NH.OH dropwise to the sample until
the indicator changes color.
9. Continue wanning and stirring for another 30 minutes.
10. Filter sample through a membrane and wash precipitate with 25 ml
distilled water.
11. Mount the filter membrane on a planchet using double stick tape.
12. Carefully dry the precipitate and count for alpha activity.
13. Prepare a reagent blank precipitate to determine reagent
background.
14. Store samples in a desiccator or dry carefully under a heat lamp
if recounted at a later date.
Calculations
Calculate the concentration, Z, of gross alpha in picocuries per
00-02-2
-------
liter as follows:
(2.22)(E)(V)
where
E = counter efficiency (see Note 1),
V = volume analyzed (liters),
2.22 = dpm/pCi,
C. = sample (counts per minute), and
CD = reagent blank (counts per minute).
o
Calculate the lower limit of detection (LLD), as follows:
LLD =
(2.22)(E)(V)(T)
where
CB = reagent background, counts per minute,
T = counting time,
E = counter efficiency,
V = sample volume (liters), and
2.22 = dpm/pCi.
This LLD calculation is valid if the sample counting time is equal to
the background counting time.
Notes
1. Determine counter efficiency by coprecipitating standardized aliquots
of alpha-emitting actinide solutions. As an example, a known quantity
00-02-3
-------
of plutonlum 1s added to a 500 ml volume of water. The plutonlum Is
copreclpltated by using the procedure described, counted and the counting
efficiency determined. Other alpha emitters such as uranium may also be
used In the manner described. At least six determinations should be made
with each standard used.
References
1. Krleger, H.L., and Whlttaker, E.L., Prescribed Procedures for
Measurement of Radioactivity in Drinking Water, EPA-600/4-80-032,
Environmental Monitoring and Support Laboratory, Office of Research
and Development, U.S. Environmental Protection Agency, Cincinnati,
Ohio (August 1980).
00-02-4
-------
RADIOCHEMICAL DETERMINATION OF LEAD-210 AMD POLOHIUM-210
IN DRY INORGANIC AND BIOLOGICAL SAMPLES
Principle
Polonium-209 and bismuth-207 tracers and lanthanum carrier are added
to a weighed aliquot of sample which has been dried at 100°C for 24
hours. The sample Is solubilized by wet ashing. The radloelements are
coprecl pita ted as hydroxide with MH.OH. The hydroxide is redissolved in
acid and the bismuth and polonium are spontaneously deposited on a clean
copper disc.
210
The disc is beta counted for Bi, gamma assayed by Ge(Li) for
207 209 210
Bi and radioassayed by alpha spectroscopy for Po and Po.
210
The Pb can be determined by measuring ingrowth of its decay daughter
210Bi which has a half-life of 5 days.
Special Apparatus
1. Copper discs made from 0.6 mm thick copper sheet. Discs are 2.2
cm diameter with a 0.3 cm hole set 0.15 cm in from the edges.
The discs are coated on one side with an acid-resistant paint.
2. Constant temperature bath maintained at 80°C. Glycerol is used
as heat transfer fluid.
3. Teflon beakers. See Mote 1.
4. Centrifuge.
5. Magnetic stirrer and stirring bars.
6. Glassware.
7. Alpha spectrometrie system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier detector,
vacuum pump and chamber.
Reagents
1. Ascorbic acid, crystalline reagent.
2. Ammonium hydroxide, 15M, reagent grade NH4OH.
00-03-1
-------
3. Hydrochloric acid, 12M, 37 percent HC1 reagent.
4. Hydrochloric acid, 6M. Dilute 500 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
5. Hydrofluoric acid, 29M, 48 percent HF reagent.
6. Lanthanum carrier, 10 mg La+3/ml. Dissolve 7.8g high purity
La(N03)3* 6H20 in 250 ml distilled water.
7. Nitric acid, 16M, 70 percent HN03 reagent.
8. Bismuth-207 tracer solution. Approximately 10 pCi/ml.
9. Polonium-209 tracer solution. Approximately 1 pCi/ml.
Procedure
1. Add measured aliquot of Bi-207 and Po-209 tracers and 1 ml
lanthanum carrier to weighed one gram aliquot of sample in a
Teflon beaker.
2. Add 15 ml 29M HF and 10 ml 16M HN03 and evaporate to near
dryness. Repeat this step.
3. Add three successive 10 ml volumes of 6f1 HC1. Evaporate to near
dryness following each addition.
4. Take up sample in 40 ml 6M HC1 and cover with watch glass while
warming sample for 30 minutes.
5. Transfer dissolved sample to 250 ml centrifuge bottle.
6. Make sample basic with careful addition of 15M NH4OH with
stirring.
7. Allow sample to stand for 30 minutes and centrifuge after
precipitate has formed.
8. Pour off supernate. Wash precipitate with 25 ml water.
Centrifuge and pour off wash water.
9. Dissolve precipitate by adding 1-ml increments of 12M HC1. Use
stirring rod to break up precipitate, using minimum amount of HC1.
10. Place small magnetic stirring bar in centrifuge bottle and slowly
add 100 ml water with stirring.
00-03-2
-------
11. Transfer centrifuge bottle to constant temperature bath
maintained at 80°C.
12. If yellow color 1s evident, add ascorbic acid in 50-mg increments
until Fe color is gone.
13. Prepare copper disc by cleaning bare side with copper cleaner and
dipping disc in 12M HC1.
14. Suspend disc, using glass rod, into centrifuge bottle, keeping
disc under surface of liquid.
15. Maintain sample at bath temperature of 80°C for four hours.
16. Remove disc, rinse with water and air dry.
17. Mount on 32 mm planchet with double stick tape for radioassay.
00-03-3
-------
Appendix
Preparation of Bismuth-207 Standard Solution
Bismuth-207 decays by electron capture to lead-207m, which emits a
gamma ray at 570 keV.
207
1. Evaporate a measured aliquot of the B1 standard solution on
a copper disc.
2. Radioassay the disc with a Ge(Li) detector for 1,000 minutes and
record the net counts appearing under the 570 keV peak.
3. Radioassay the disc for beta activity using a beta counter having
2
a window of 7 rag/cm thickness. This assay determines the
contribution to the beta background from the bismuth-207 added to
the sample.
Calculations
Calculate the concentration, Z, of lead-210, bismuth-210 in
picocuries per sample as follows:
Z = Cl - CCB *
-------
Calculate the concentration, Z, of polom'um-210 In picocurles per
unit sample as follows:
x F e ~xt
(2.22 (B-BjMEMVMT)
where
A = gross sample counts which appear In the polom'um-210 alpha
energy region,
A = background counts In the same alpha energy region as /t above,
B = gross tracer counts which appear 1n the alpha energy region
of the tracer Isotope,
B. = background counts In the same alpha energy region as § above,
E = alpha detector efficiency,
F = total calibrated tracer counts for same counting time as
sample counts,
x = decay constant for polom'um-210, days' ,
t = time from separation to counting In days,
V = sample unit (liters or grams),
T = counting time (minutes), and
2.22 = dpm per pCI.
Calculate the lower limit of detection (LLD) for bismuth or polonium
In picocurles per unit sample as follows:
LLD
4.66V
(2.22)(E)(R)(V)(T)
where
CD = background count rate,
00-03-5
-------
T = counting time (same for sample and background),
E = alpha detector efficiency,
R = fractional yield based on B-B-i/F In calculation, for Po
210
(see R, B1 calculation for B1),
V = sample unit (liters or grams), and
2.22 = dpm per pCI.
This LLD calculation is valid if the sample counting time is equal to
the background counting time.
Notes
1. Teflon Is a registered tradmark of the DuPont Co., Wilmington, DE.
References
1. Blanchard, R. L., "Rapid Determination of Lead-210 and Polonium-210 in
Environmental Samples by Deposition on Nickel," Analytical Chemistry,
38, 189 (1966).
00-03-6
-------
RADIOCHEMICAL DETERMINATION OF PLUTONIUM, THORIUM
AND URANIUM IN AIR FILTERS
Principle
The cellulose air filters are ashed at 550°C for 48 hours.
Plutonium-242, thorium-234, and uranium-232 tracers are added to determine
chemical yield. Silica is volatilized with HF and the residue is
solubilized. Plutonium and uranium are extracted into triisooctylamine
(TIOA). The thorium is purified by adsorption on anion exchange resin
from nitric acid. Plutonium and uranium are stripped from the TIOA with
dilute nitric acid and selectively coprecipitated with 0.1 mg lanthanum as
fluoride. The precipitates are filtered on filter membranes and
radioassayed by alpha spectroscopy for plutonium and uranium.
Special Apparatus
1. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore size
or equivalent. See Note 1.
2. Ion exchange column, 2 cm I.D. x 10 cm.
3. Plastic graduated cylinder, 100 ml volume.
4. Planchets, stainless steel, 32 mm diameter.
5. Separatory funnels, 1 liter capacity.
6. Suction filter for 25 mm membrane.
7. Teflon beakers. See Note 2.
8. Glassware.
9. Alpha spectrometric system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier detectors,
vacuum pump and chamber.
Reagents
1. Anion exchange resin; BioRad AG1X8 (200-400 mesh, nitrate form)
or equivalent. Convert to nitrate form for thorium analysis by
washing the resin with 6J1 HNOg until the washing shows no trace
00-04-1
-------
of chloride, when tested with AgNO-j.
2. Ascorbic acid, crystalline reagent.
3. Ethanol, 95 percent reagent.
4. Hydrochloric acid, 12M. 37 percent HC1 reagent.
5. Hydrochloric acid, 9f1. Dilute 750 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
6. Hydrochloric acid, 1M. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
7. Hydrofluoric acid, 29M, 48 percent HF reagent.
8. Hydrofluoric acid, 3M,. Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic graduate
and storage bottle.
9. Hydrogen peroxide, 50 percent reagent grade.
10. Lanthanum carrier, 0.1 mg La* /ml. Dissolve 0.0779 g
La(N03)3« 6H20 per 250 ml 1M HC1.
11. Nickel foil, 15 cm x 1 cm x 0.1 mm.
12. Nitric acid, 16M, 70 percent HN03 reagent.
13. Nitric acid, 6M. Dilute 375 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
14. Nitric acid, O.M. Dilute 6 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
15. Perchloric acid, 12M, 70 percent HC104 reagent.
16. Silver nitrate, crystalline reagent.
17. Silver nitrate, O.M. Dissolve 1.7 g AgN03 reagent in
distilled water. Add 1 ml 6M HN03 and dilute to 100 ml with
distilled water.
18. Titanium trichloride, 20 percent reagent grade.
19. Titanium trichloride, 0.4 percent. Dilute 1 ml of the 20 percent
T1C13 to 50 ml with 1 Q HC1. Prepare fresh daily.
20. Triisooctylamine (TIOA), reagent grade.
21. TIOA solution in p-xylene, 10 percent. Dissolve 100 ml of
trilsooctylamine in p-xylene and dilute to 1 liter with p-xylene.
00-04-2
-------
22. p-Xylene, reagent grade.
23. Thorium-234 tracer solution, approximately 800 pCi/ml, accurately
calibrated.
24. Uranium-232 tracer solution, approximately 1 pC1/ml, accurately
calibrated.
25. PIutonium-242 tracer solution, approximately 1 pCi/ml, accurately
calibrated.
Sample Preparation
1. Place air filter samples in a ceramic dish for ashing.
2. Ash in muffle furnace, gradually raising temperature over several
hours to 550°C. Maintain temperature for 48 hours.
3. Carefully weigh cooled ash and transfer to Teflon beaker. Add 1
ml each of 242Pu, 234Th, and 232U tracers.
4. Add 20 ml of 29^1 HF and evaporate to dry ness to remove SiF^.
Repeat.
5. Dissolve the residue in 200 ml 9{4 HC1 and transfer solution to a
separator/ funnel.
6. Wash beaker with 25 ml 9M^HC1 and add solution to separator/
funnel.
7. Add 2 ml of 50 percent H202, heat gently and set aside for 10
minutes. See Note 3.
Plutonium Determination
1. Place 100 ml of 10 percent TIOA solution in a 1 liter separator/
funnel. Add 50 ml 9M HC1 and shake funnel for one minute. Drain
and discard lower aqueous acid phase after clean separation of
the two phases.
2. Add the aqueous sample to the TIOA in the separator/ funnel and
shake the funnel vigorously for two minutes. Vent the funnel '
stopcock to prevent pressure buildup in the funnel.
00-04-3
-------
3. Allow the phases to separate cleanly and draw off the lower
aqueous acid phase. Save acid phase for thorium determination.
4. Add 50 ml 9^1 HC1 to the TIOA solution 1n the separatory funnel
and shake for one minute.
5. Allow the phases to separate; withdraw and discard lower aqueous
acid phase.
6. Repeat steps 4 and 5.
7. Strip the plutonium from the TIOA solution by adding 100 ml 0.1M
HN03 to the separatory funnel and shaking the funnel for two
minutes.
8. Allow phases to separate; withdraw and transfer lower acid phase
to separatory funnel.
9. Repeat steps 7 and 8 and combine strip solutions. Discard TIOA.
10. Place combined strip solutions in a separatory funnel.
11. Add 100 ml p-xylene to combined strip solution and shake funnel
for one minute. See Note 4.
12. Allow phases to separate cleanly; withdraw lower aqueous acid
layer into beaker. Discard p-xylene.
13. Evaporate combined solution from step 12 to dryness. Do not
overheat.
14. Add 10 ml 16M HN03 to residue and evaporate to dryness. Do not
overheat.
15. Add 5 ml 9h1 HC1 and 5 ml 12M HCIO^ to residue and evaporate to
dryness.
16. Repeat step 15.
17. Add 10 ml 12M HC1 and evaporate to dryness.
18. Repeat step 17.
19. Add 50 ml 1M HC1 to sample residue and warm gently to dissolve
residue.
•
20. Heat sample solution to 80°C with stirring and add 50 mg ascorbic
acid. Do not overheat.
00-04-4
-------
21. Suspend clean nickel metal strip into solution for two hours to
remove polonium.
22. Remove nickel and evaporate the solution to dryness.
23. Add 15 ml 1M_ HC1 to sample residue and warm to approximately 50°C,
24. Add 0.5 ml 50 percent HgOg, 1 ml of lanthanum carrier and 5
ml of 3M HF to precipitate LaF-j. Mix well and set aside for 30
minutes.
25. Using suction, filter coprecipitated sample through a filter
membrane. Save filtrate for uranium analyses.
26. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
27. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
28. Mount membrane carefully on 32 mm planchet using double stick
tape.
29. Count sample for 1000 minutes on alpha spectrometer.
Uranium Determination
1. Evaporate filtrate from step 25 of.the plutonium determination.
2. Add 10.ml 12M HC1 to residue and evaporate to dryness. Repeat
this step.
3. Add 15 ml 1M_ HC1 to sample residue and warm to approximately 50°
C.
4. Add enough ascorbic acid to reduce iron in the sample, indicated
by the disappearance of yellow color.
5. Add 1 ml of 0.4 percent T1C13 to reduce uranium.
6. Add 1 ml of lanthanum carrier and 5 ml of 3 M HF. Mix well and
set aside for 30 minutes.
7. Using suction, filter coprecipitated sample through a filter
membrane.
8. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
00-04-5
-------
9. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
10. Mount membrane carefully on 32 mm planchet using double stick
tape.
11. Count sample for 1000 minutes on alpha spectrometer.
Thorium Determination
1. Evaporate aqueous acid fraction containing thorium from step 3 of
Plutonium determination.
2. Add 10 ml 16M HN03 and evaporate to dryness.
3. Add 5 ml 9M_ HC1 and 5 ml 12M HC104 and evaporate to dryness.
4. Add 10 ml of 16M_ HNOj and evaporate to dryness.
5. Repeat step 4.
6. Dissolve sample In 10 ml of 6M_ HNOj with heat.
7. Prepare Ion exchange column with 25 ml BloRad AG1X8 resin. Wash
resin with 250 ml of 6M HN03.
8. Decant sample Into column at gravity flow (approx. 3ml/m1n) and
rinse the sample on the column with an additional 50 ml of 6M_
HN03. Discard wash.
9. Elute the thorium from the column with 200 ml of 6M HC1 at flow
rate of 3 ml/minute.
10. Evaporate thorium eluate to dryness.
11. Wet ash residue with 10 ml 12M HC1 and evaporate to dryness.
12. Add 15 ml 1M_ HC1 to sample residue and warm to approximately 50°C.
13. Add 1 ml lanthanum carrier and 5 ml of 3M_ HF to precipitate
LaF3. Mix well and set aside for 30 minutes.
14. Using suction, filter coprecipitated sample through a filter
membrane.
15. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
16. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
00-04-6
-------
17. Mount membrane carefully on 32 mm planchet using double stick tape.
18. Beta count the sample to measure thorium-234 recovery.
19. Count sample for 1000 minutes on alpha spectrometer.
Calculations
Calculate the concentration, Z, of plutom'um in picocuries per cubic
meter as follows:
x F
(2.22)(B-B1)(E)(V)(T)
where
A = gross sample counts which appear in the plutonium-238 or
plutonium-239 alpha energy region,
A. = background counts in the same alpha energy region as £ above,
B = gross tracer counts which appear in the alpha energy region
of the tracer isotope,
BI = background counts in the same alpha energy region as £ above,
E = alpha detector efficiency,
F = total calibrated tracer counts for same counting time as
sample counts,
V = sample volume (cubic meters of air),
T = counting time (minutes), and
2.22 = dpm per pCi.
Calculate the concentration, Z, of uranium in picocuries per cubic
meter as follows:
z = (A-Aj) x F
(2.22)(B-B1)(E)(V)(T)
00-04-7
-------
where
A = gross sample counts which appear in the uranium-234,-235,
or-238 alpha energy region,
Aj = background counts In the same alpha energy region as A above,
B = gross tracer counts which appear in the alpha energy region
of the tracer isotope,
B^ = background counts in the same alpha energy region as B_ above.
E = alpha detector efficiency,
F = total calibrated tracer counts for same counting time as
sample counts,
V = sample volume (cubic meters of air),
T = counting time (minutes), and
2.22 = dpm per pd.
Calculate the concentration, Z, of thorium in picocuries per cubic
meter as follows:
z m (A - AJ) x F
(2.22HB - BjMEMVHT)
where
A = gross sample counts which appear in the thorium -227, -228,
-230 or -232 alpha energy region,
A. = background counts In the same alpha energy region as A^ above,
B = gross tracer beta counts,
Bj = beta counter background,
E = alpha detector efficiency,
F = total calibrated tracer beta counts,
V = sample volume (cubic meters of air),
T = counting time (minutes), a* d
2.22 = dpm per pd.
00-04-8
-------
Calculate the lower limit of detection (LID) in picocuries per cubic
meter as follows:
LLD = 4'66
(2.22)(E)(R)(V)(T)
where
CB = background count rate,
T = counting time (same for sample and background),
E = alpha detector efficiency,
R = fractional yield based on B-Bj/F in calculation,
V = sample volume (cubic meters of air), and
2.22 = dpm per pCi.
This LLD calculation is valid if the sample counting time is equal to
the background counting time.
Notes
1. Nuclepore is a registered trademark of Nuclepore Corp., Pleasanton, CA.
2. Teflon is a registered trademark of Dupont Co., Wilmington, DE.
3. Hydrogen peroxide stabilizes the +4 plutonium valence necessary for
maximum extraction into the TIOA.
4. The p-xylene removes most of the TIOA carried into the aqueous acid
phase. Residual TIOA makes the coprecipitation step more difficult.
References
1. Moore, F.L., "Liquid-Liquid Extraction of Uranium and Plutonium from
Hydrochloric Acid Solution with Tri(iso-octy1)amine," Analytical
Chemistry 30, 908 (1958).
00-04-9
-------
2. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual, 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
New York.
3. Johns, F.B., et al., Radlochemcal Analytical Procedures for Analysis
of Environmental Samples, EMSL-LV-0539-17, U.S. E.P.A., Las Vegas, NV.
00-04-10
-------
RADIOCHEMICAL DETERMINATION OF THORIUM AND URANIUM IN ASHED
SAMPLES INCLUDING SOIL, COAL, FLY ASH, ORES. VEGETATION AND BIOTA
Fusion Method
Principle
The sample is ashed at 550 °C for 72 hours. Thorium-234 and
uranium-232 tracers are added to a weighed aliquot. Silica is volatilized
and the sample is fused with potassium fluoride and potassium
pyrosulfate. The uranium is extracted into triisooctylamine (TIOA). The
thorium is purified by adsorption on anion exchange resin from nitric
acid. Uranium is stripped from the resin with HC1 and coprecipitated.
Each actinide isotope is radioassayed by alpha spectroscopy.
Special Apparatus
1. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore
size or equivalent. See Note 1.
2. Ion exchange column, 2 cm I.D. x 10 cm.
3. Plastic graduated cylinder, 100 ml capacity.
4. Planchets, stainless steel, 32 mm diameter.
5. Separatory funnels, 1 liter capacity.
6. -Suction filter for 25 mm membrane.
7. Teflon beakers. See Mote 2.
8. Glassware.
9. Platinum Crucible.
10. Alpha spectrometric system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier detector,
vacuum pump and chamber.
11, Meker burner.
Reagents
1. Anion exchange resin; BioRad AG1X8 (200-400 mesh, nitrate form)
00-05-1
-------
or equivalent. Convert to nitrate form for thorium analysis by
washing the resin with 6M HN03 until the washing shows no trace
of chloride, when tested with AgNO-j.
2. Ascorbic acid, crystalline reagent.
3. Hydrochloric acid, 12M. 37 percent HC1 reagent.
4. Hydrochloric acid, 9M. Dilute 750 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
5. Hydrochloric acid, 1M. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
6. Hydrofluoric acid, 29M, 48 percent HF reagent.
7. Hydrofluoric acid, 3M,. Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic graduate
and storage bottle.
8. Lanthanum carrier, 0.1 mg La /ml. Dissolve 0.0779 g
La(N03)3* 6H20 per 250 ml 1M HC1.
9. Nickel foil, 15 cm x 1 cm x 0.1 mm.
10. Nitric acid, 16M, 70 percent HN03 reagent.
11. Nitric acid, 6M. Dilute 375 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
12. Nitric acid, 0.1M. Dilute 6 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
13. Perchloric acid, 12M, 70 percent HC104 reagent.
14. Potassium fluoride, crystalline reagent.
15. Potassium pyrosulfate, crystalline reagent.
16. Silver nitrate, crystalline reagent.
17. Silver nitrate, O.IM^ Dissolve 1.7 g AgN03 reagent in
distilled water. Add 1 ml 6M HN03 and dilute to 100 ml with
distilled water. Keep in brown bottle.
18. Sulfuric acid, 3M. Dilute 167 ml of the 96 percent H2S04
reagent to 1 liter with distilled water.
19. Titanium trichloride, 20 percent reagent grade.
00-05-2
-------
20. Titanium trichloride, 0.4 percent. Dilute 1 ml of the 20 percent
T1C13 to 50 ml with 1 M HC1. Prepare fresh daily.
21. Triisooctylamine (TIOA), reagent grade.
22. TIOA solution in p-xylene, 10 percent. Dissolve 100 ml of
triisooctylamine in p-xylene and dilute to 1 liter with p-xylene.
23. p-Xylene, reagent grade.
24. Thorium-234 tracer solution, approximately 800 pCi/ml, accurately
calibrated.
25. Uranium-232 tracer solution, approximately 1 pCi/ml, accurately
calibrated.
Sample Preparation
1. Place 100 g sample in ceramic dish for ashing.
2. Ash in muffle furnace, gradually raising temperature over several
hours to 550°C. Maintain at temperature for 72 hours.
3. Carefully weigh 1 g aliquot of cooled ash and transfer to Teflon
beaker. Add 1 ml each of 234Th and 232U tracers.
4. Wet ash with two additions of 20 ml each 29M HF and evaporate
each time to dry ness.
5. Transfer the residue to a platinum crucible with the aid of a
spatula. Use a 20 ml crucible for a 1 g sample.
6. Add 2g of KF for a Ig sample or 4g KF for a 5g sample and fuse
covered over a Meker burner for 30 minutes.
7. Add 7.5 grams KgSgOy for a 5-gram sample or 3 grams for a
1-gram sample and continue fusing for 30 minutes.
8. Cool the crucible in an ice bath, add 15 ml 12M HC1 and evaporate.
9. Add 15 ml of water and partially evaporate to 10 ml volume.
10. Transfer to 1000-ml beaker and add 150 ml water.
11. Heat and evaporate to dry ness and add 200 ml 3^1 f^SO^.
Evaporate past white fumes to dryness.
12. Dissolve the residue in 200 ml 9M HC1.
00-05-3
-------
Uranium Determination
1. Place 100 ml of 10 percent TIOA solution In a 1 liter separator/
funnel. Add 50 ml 9f1 HC1 and shake funnel for 1 minute. Drain
and discard lower aqueous acid phase after clean separation of
the two phases.
2. Add the aqueous sample from step 12 above, to the TIOA In the
separator/ funnel and shake the funnel vigorously for two
minutes. Vent the funnel stopcock to prevent pressure buildup In
the funnel.
3. Allow the phases to separate cleanly and draw off the lower
aqueous acid phase. Save for thorium analysis.
4. Add 50 ml 9J1 HC1 to the TIOA solution In the separatory funnel
and shake for 1 minute.
5. Allow the phases to separate; withdraw and discard lower aqueous
acid phase.
6. Repeat steps 4 and 5.
7. Strip the uranium from the TIOA solution by adding 100 ml 0.1 M
H,M03 to the separatory funnel and shaking the funnel for 2
minutes.
8. Allow phases to separate; withdraw and save lower acid phase,
discard organic phase.
9. Repeat steps 7 and 8 and combine strip solutions.
10. Place combined strip solutions In the clean separatory funnel.
11. Add 100 ml p-xylene to combined strip solution and shake funnel
for 1 minute. See Note 3.
12. Allow phases to separate cleanly; withdraw lower aqueous acid
layer Into beaker.
13. Evaporate combined solution from step 12 to dryness. Discard
organic phase. Do not overheat.
14. Add 100 ml 16f1 HNOj to residue and evaporate to dryness. Do
not overheat.
00-05-4
-------
15. Add 5 ml 9M HC1 and 5 ml 12M HC104 to residue and evaporate to
dry ness.
16. Repeat step 15.
17. Add 10 ml 12M HC1 and evaporate to dryness.
18. Repeat step 17.
19. Add 50 ml 1M HC1 to sample residue and warm gently to dissolve
residue.
20. Heat sample solution to 80°C with stirring and add 50 mg ascorbic
acid. Do not overheat.
21. Suspend clean nickel metal strip into solution for two hours to
remove polonium.
22. Remove nickel and evaporate solution to dryness.
23. Add 15 ml 1M_ HC1 to sample residue and warm to approximately 50°C.
24. Add enough ascorbic acid to reduce iron in the sample, Indicated
by the disappearance of yellow color.
25. Add 1 ml of 0.4 percent TiClj to reduce uranium.
26. Add 1 ml of lanthanum carrier and 5 ml of 3M_ HF. Mix well and
set aside for 30 minutes.
27. Using suction, filter coprecipitated sample through a filter
membrane.
28. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
29. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
30. Mount membrane carefully on 32 mm planchet using double stick
tape.
31. Count sample for 1000 minutes on alpha spectrometer.
Thorium Determination
1. Evaporate aqueous acid fraction containing thorium from step 3 of
.Uranium Determination.
2. Add 10 ml 16M_ HNOj and evaporate to dryness.
00-05-5
-------
3. Add 5 ml 9f1 HC1 and 5 ml 12M HC104 and evaporate to dryness.
4. Add 10 ml of 16M_ HM03 and evaporate to dryness.
5. Repeat step 4.
6. Dissolve sample In 10 ml of 6^ HN03 with heat.
7. Prepare ion exchange column with 25 ml BioRad AG1X8 resin. Wash
resin with 250 ml of 6M HN03.
8. Decant sample into column at gravity flow (approx. 3ml/min) and
rinse the sample on the column with an additional 50 ml of 6M^
HN03. Discard wash.
9. Elute the thorium from the column with 200 ml of 6M HC1 at flow
rate of 3 ml/minute.
10. Evaporate thorium eluate to dryness.
11. Add 10 ml 12M HC1 to residue and evaporate to dryness.
12. Add 15 ml 1M_ HC1 to sample residue and warm to approximately 50°C.
13. Add 1 ml lanthanum carrier and 5 ml of 3M HF. Mix well and set
aside for 30 minutes.
14. Using suction, filter coprecipitated sample through a filter
membrane.
15. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
16. Remove clamp and top of funnel with suction on. Allow membrane to
dry.
17. Mount membrane carefully on 32 mm planchet using double stick tape.
18. Beta count the sample to measure thorium-234 recovery*
19. Count sample for 1000 minutes on alpha spectrometer.
Calculations
Calculate the concentration, Z, of uranium in picocuries per gram as
follows:
(A-A) x F
(2.22)(B-B1)(E)(W)(T)
00-05-6
-------
where
A = gross sample counts which appear in the uram'um-234,-235,
or-238 alpha energy region,
Aj = background counts in the same alpha energy region as A above,
B = gross tracer counts which appear in the alpha energy region
of the tracer isotope,
B^ = background counts in the same alpha energy region as jJ above,
E = alpha detector efficiency,
F = total calibrated tracer counts for same counting time as
sample counts,
W = sample weight (grams),
T = counting time (minutes), and
2.22 = dpm per pCi.
Calculate the concentration, Z, of thorium 1n picocuries per gram as
fol1ows:
Zm (A - A1) x F
(2.22HB - BjHEHHHT)
where
A = gross sample counts which appear in the thorium -227, -228,
-230 or -232 alpha energy region,
A. = background counts in the same alpha energy region as A above,
B = gross tracer beta counts,
BI = beta counter background,
E = alpha detector efficiency,
F = total calibrated tracer beta counts,
W = sample weight (grams),
T = counting time (minutes), and
2.22 = dpm per pC1.
00-05-7
-------
Calculate the lower limit of detection (LLD) for uranium or thorium
in picocuries per gram as follows:
4.66 V CRT
LLD
(2.22)(E)(R)(W)(T)
where
CB = background count rate,
T = counting time; same for sample and background,
E = alpha detector efficiency,
R = fractional yi Id based on B-Bj/F in calculation,
W = sample weight (grams), and
2.22 = dpm per pCi.
This LLD calculation is valid if the sample counting time is the same
as the background counting time.
Notes
1. Nuclepore is a registered trademark of Nuclepore Corp., Pleasanton, CA.
2. Teflon is a registered trademark of Dupont, Co., Wilmington, DE.
3. The p-xylene removes most of the TIOA carried into the aqueous acid
phase. Residual TIOA makes the coprecipitation step more difficult.
References
1. Moore, F.L., "Liquid-Liquid Extraction of Uranium and Plutonium from
Hydrochloric acid Solution with Tri (iso-octyl) amine," Analytical
Chemistry 30, 908 (1958).
2. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual. 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
New York.
3. Johns, F.B., et al., Radiochemical Analytical Procedures for Analysis
of Environmental Samples, EMSL-LV-0539-17, U.S. E.P.A., Las Vegas, NV,
(1979).
00-05-8
-------
RADIOCHEMICAL DETERMINATION OF THORIUM AND URANIUM IN ASHED SAMPLES
Nonfusion Method
Principle
The sample Is ashed at 550°C for 72 hours. Thorlum-234 and
uran1um-232 tracers are added to 1 g allquots. Silica Is volatilized with
HF and the residue 1s solublllzed. The uranium Is extracted Into
trllsooctylamlne (TIOA), stripped from the TIOA with nitric acid and
coprecipitated. The thorium Is purified by adsorption on anlon exchange
resin from nitric acid, stripped from the resin with HC1 and
coprecipitated. Each Isotope Is radloassayed by alpha spectroscopy.
Special Apparatus
1. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore size
or equivalent. See Note 1.
2. Ion exchange column, 2 cm Internal diameter x 10 cm.
3. Plastic graduated cylinder.
*•
4. Planchets, stainless Steel, 32 nrnf.diameter.
5. Separatory funnels, 1 liter capacity.
6. Suction filter for 25 mm membrane.
7. Teflon beakers. See Note 2.
8. Glassware.
9. Alpha spectrometrlc system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier detectors,
vacuum pump and chamber.
Reagents
1. Anlon exchange resin; BloRad AG1X8 (200-400 mesh, nitrate form) or
equivalent. Convert to nitrate form for thorium analysis by
washing the resin with 6M_ HN03 until the washing shows no trace
of chloride when tested with AgN03.
00-06-1
-------
2. Ascorbic acid, crystalline reagent.
3. Hydrochloric acid, 12M. 37 percent HC1 reagent.
4. Hydrochloric add, 9M. Dilute 750 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
5. Hydrochloric acid, 1M. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
6. Hydrofluoric add, 29M, 48 percent HF reagent.
7. Hydrofluoric acid, 3M^ Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic
graduated cylinder and storage bottle.
8. Lanthanum carrier, 0.1 mg La*3/ml. Dissolve 0.0779 g
La(N03)3* 6H20 per 250 ml 1M HC1.
9. Nickel foil, 15 cm x 1 cm x 0.1 mm.
10. Nitric acid, 16^, 70 percent HN03 reagent.
11. Nitric acid, 6M. Dilute 375 ml of the 70 percent reagent grade
HH03 to 1 liter with distilled water.
12. Nitric acid, 0.1^. Dilute 6 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
13. Perchloric acid, 12M, 70 percent HC104 reagent.
14. Silver nitrate, crystalline reagent.
15. Silver nitrate, O.W. Dissolve 1.7 g AgN03 reagent in
distilled water. Add 1 ml 6M HN03 and dilute to 100 ml with
distilled water.
16. Titanium trichloride, 20 percent reagent grade.
17. Titanium trichloride, 0.4 percent. Dilute 1 ml of the 20 percent
TiCl3 to 50 ml with 1 M HC1. Prepare fresh dally.
18. Triisooctylamine (TIOA), reagent grade.
19. TIOA solution in p-xylene, 10 percent. Dissolve 100 ml of
triisooctylamine 1n p-xylene and dilute to 1 liter with p-xylene.
20. p-Xylene, reagent grade.
21. Thorium-234 tracer solution, approximately 800 pC1/ml, accurately
calibrated.
00-06-2
-------
22. Uranium-232 tracer solution, approximately 1 pCI/ml, accurately
calibrated.
Sample Preparation
1. Place lOOg sample in ceramic dish for ashing.
2. Ash in muffle furnace, gradually raising temperature over several
hours to 550°C. Maintain temperature for 72 hours.
3. Carefully weigh Ig aliquot of cooled ash and transfer to Teflon
beaker. Add 1 ml each of 234Th and 232U tracers.
4. Treat sample with two additions of 20 ml each 29M HF and
evaporate each time to dryness.
Uranium Determination
1. Add 5 ml of 12M HC104 and 5 ml of 9M HC1 to sample and
evaporate to dryness. Repeat this step.
2. Add 10 ml of 12M HC1 and transfer sample to glass beaker.
Evaporate to dryness and repeat this step.
3. Dissolve sample in 300 ml of 9M^ HC1 and warm to approximately
50*C.
4. Place 100 ml of 10 percent TIOA solution in a 1 liter separatory
funnel. Add 50 ml 9M HC1 and shake funnel for 1 minute. Drain
and discard lower aqueous acid phase after clean separation of
the two phases.
5. Add the aqueous sample to the TIOA 1n the separatory funnel and
shake the funnel vigorously for two minutes. Vent the funnel
stopcock to prevent pressure buildup in the funnel.
6. Allow the phases to separate cleanly and draw off the lower
aqueous acid phase. Save for thorium analysis.
7. Add 50 ml 9M HC1 to the TIOA solution in the separatory funnel
and shake for one minute.
8. Allow the phases to separate; withdraw and discard lower aqueous
acid phase.
00-06-3
-------
9. Repeat steps 7 and 8.
10. Strip the uranium from the TIOA solution by adding 100 ml 0.1 *1
HN03 to the separatory funnel and shaking the funnel for two
minutes.
11. Allow phases to separate; withdraw and save lower acid phase.
12. Repeat steps 10 and 11 and combine strip solutions.
13. Place combined strip solutions in clean separatory funnel.
14. Add 100 ml p-xylene to combined strip solution and shake funnel
for 1 minute. See Note 3.
15. Allow phases to separate cleanly; withdraw lower aqueous acid
layer into beaker. Discard p-xylene.
16. Evaporate solution from step 15 to dryness. Do not overheat.
17. Add 100 ml 16M^ HN03 to residue and evaporate to dryness. Do
not overheat.
18. Add 5 ml 9M HC1 and 5ml 1234 HC104 to residue and evaporate to
dryness.
19. Repeat step 18.
20. Add 10 ml 12M HC1 and evaporate to dryness.
21. Repeat step 20.
22. Add 50 ml 1M_ HC1 to sample residue and warm gently to dissolve
residue.
23. Heat sample solution to 80°C with stirring and add 50 mg ascorbic
acid. Do not overheat.
24. Suspend clean nickel metal strip into solution for two hours to
remove polonium.
25. Remove nickel and evaporate solution to dryness.
26. Add 15 ml 1M_ HC1 to sample residue and warm to approximately 50°C.
27. Add enough ascorbic acid to reduce iron in the sample, indicated
by the disappearance of yellow color.
28. Add 1. ml of 0.4 percent TiCl, to reduce uranium.
29. Add 1 ml of lanthanum carrier and 5 ml of 3 M HF. Mix well and
set aside for 30 minutes to precipitate LaF- carrying uranium.
00-06-4
-------
30. Using suction, filter copreclpltated sample through a filter
membrane.
31. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
32. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
33. Mount membrane carefully on 32 mm planchet using double stick
tape.
34. Count sample for 1000 minutes on alpha spectrometer.
Thorium Determination
1. Evaporate aqueous acid fraction containing thorium from step 6 of
Uranium Determination.
2. Add 10 ml 16M HNOj and evaporate to dryness.
3. Add 5 ml 9M HC1 and 5 ml 12M HC104 and evaporate to dryness.
4. Add 10 ml of 16f1 HN03 and evaporate to dryness.
5. Repeat step 4.
6. Dissolve sample in 10 ml of 6M_ HN03 with heat.
7. Prepare ion exchange column with 25 ml BloRad AG1X8 resin. Wash
resin with 250 ml of 6M HN03.
8. Decant sample into column at gravity flow (approx. 3ml/min) and
rinse the sample on the column with an additional 50 ml of 6M_
HN03. Discard wash.
9. Elute the thorium from the column with 200 ml of 6M HC1 at flow
rate of 3 ml/minute.
10. Evaporate thorium eluate to dryness.
11. Add 10 ml 12M HC1 to residue and evaporate to dryness.
12. Add 15 ml 1M HC1 to sample residue and warm to approximately 50°C,
13. Add 1 ml lanthanum carrier and 5 ml of 3M^ HF. Mix well and set
aside for 30 minutes to precipitate LaF3 carrying thorium.
14. Using suction, filter coprecipitated sample through a filter
membrane.
00-06-5
-------
15. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
16. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
17. Mount membrane carefully on 32 mm planchet using double stick
tape.
18. Beta count the sample to measure thorlum-234 recovery.
19. Count sample for 1000 minutes on alpha spectrometer.
Calculations
Calculate the concentration, I, of uranium In picocurfes per gram as
follows:
where
Z =
(A-AX) x F
A = gross sample counts which appear 1n the uranfum-234,-235,
or-238 alpha energy region,
A. = background counts In the same alpha energy region as A above,
B = gross tracer counts which appear In the alpha energy region
of the tracer Isotope,
B. = background counts In the same alpha energy region as B_ above,
E = alpha detector efficiency,
F = total calibrated tracer counts for same counting time as
sample counts,
W = sample weight (grams),
T = counting time (minutes), and
2.22 = dpm per pCI.
00-06-6
-------
Calculate the concentration, 2, of thorium in plcocuries per gram as
follows:
(A -
x F
(2.22HB -
where
E
F
W
T
2.22
gross sample counts which appear in the thorium -227, -228,
-230 or -232 alpha energy region,
background counts In the same alpha energy region as A above,
gross tracer beta counts,
beta counter background,
alpha detector efficiency,
total calibrated tracer beta counts,
sample weight (grams),
counting time (minutes), and
dpm per pCi.
Calculate the lower limit of detection (LLD) of uranium or thorium in
picocuries per gram as follows:
LLD
(2.22)(E)(R)(W)(T)
where
A, = background counts in the same alpha energy region as A_ above,
T = counting time; same for sample and background,
E = alpha detector efficiency,
R = fractional yi Id based on B-Bj/F in calculation,
W = sample weight (grams), and
2.22 = dpm per pCi.
00-06-7
-------
This LLD calculation is valid if the sample counting time is same as
the background counting time.
Notes
1. Nuclepore is a registered trademark of Nuclepore Corp., Pleasanton, CA.
2. Teflon is a registered trademark of Dupont, Co., Wilmington, DE.
3. The p-xylene removes most of the TIOA carried into the aqueous acid
phase. Residual TIOA makes the coprecipitation step more difficult.
References
1. Moore, F.L., "Liquid-Liquid Extraction of Uranium and Plutonium from
Hydrochloric acid Solution with Tri (iso-octyl) amine," Analytical
Chemistry 30. 908 (1958).
2. Volchok, H. L. and dePlanque, G., editors, EML Procedures Manual, 25th
Ed., Environmental Measurement Laboratory, U.S. Department of Energy,
New York.
3. Johns, F.B., et al., Radiochemical Analytical Procedures for Analysis
of Environmental Samples, EMSL-LV-0539-17, U.S. E.P.A., Las Vegas, NV,
(1979).
00-06-8
-------
RADIOCHEMICAL DETERMINATION OF THORIUM AND URANIUM IN WATER
Principle
The water sample 1s filtered. Thorlum-234 and uranlum-232 tracers are
added to 1 to 4 liter allquots. After evaporation, the uranium 1s
extracted Into tr11soocty1 amine (TIOA). The thorium Is purified by
adsorption on anlon exchange resin from nitric acid. Uranium Is stripped
from the TIOA with nitric acid and copred pita ted. Thorium Is stripped
from the resin with HC1 and copred pita ted. Each actlnide 1s radloassayed
by alpha spectroscopy.
Special Apparatus
1. Nuclepore filter membranes, 25 mm dia., 0.2 micrometer pore
size or equivalent. See Note 1.
2. Ion exchange column, 2 cm internal diameter x 10 cm.
3. Plastic graduated cylinder, 100 ml volume.
4. Planchets, stainless steel, 32 mm diameter.
5. Separatory funnels, 1 liter capacity.
6. Suction filter for 25 mm membrane.
7. Teflon beakers. See Note 2.
8. Glassware.
9. Pleated filter paper.
10. Alpha spectrometric system consisting of multichannel analyzer,
biasing electronics, printer, silicon surface barrier
detectors, vacuum pump and chamber.
Reagents
1. Anlon exchange resin; BioRad AG1X8 (200-400 mesh, nitrate form)
or equivalent. Convert to nitrate form for thorium analysis by
washing the resin with 6f1 HN03 until the washing shows no
trace of chloride, when tested with AgN03.
2. Ascorbic acid, crystalline reagent.
00-07-1
-------
3. Hydrochloric acid, 12M. 37 percent HC1 reagent.
4. Hydrochloric acid, 9M. Dilute 750 ml of the 37 percent reagent
grade KC1 to 1 liter with distilled water.
5. Hydrochloric acid, IN. Dilute 83 ml of the 37 percent reagent
grade HC1 to 1 liter with distilled water.
6. Hydrofluoric acid, 29M, 48 percent HF reagent.
7. Hydrofluoric acid, 3M. Dilute 104 ml of the 48 percent reagent
grade HF to 1 liter with distilled water. Use a plastic
graduated cylinder and storage bottle.
8. Lanthanum carrier, 0.1 mg La*3/ml. Dissolve 0.0779 g
La(N03)3* 6H20 per 250 ml 1M HCl.
9. Nickel foil, 15 cm x 1 cm x 0.1 mm.
10. Nitric acid, 16M, 70 percent HN03 reagent.
11. Nitric acid, 6M. Dilute 375 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
12. Nitric acid, 0.1F1. Dilute 6 ml of the 70 percent reagent grade
HN03 to 1 liter with distilled water.
13. Perchloric acid, 12M, 70 percent HC104 reagent.
14. Silver nitrate, crystalline reagent.
15. Silver nitrate, O.lfl. Dissolve 1.7 g AgNO^ reagent in
distilled water. Add 1 ml 6M HN03 and dilute to 100 ml with
distilled water.
16. Titanium trichloride, 20 percent reagent grade.
17. Titanium trichloride, 0.4 percent. Dilute 1 ml of the 20
percent T1C13 to 50 ml with 1 K HCl. Prepare fresh dally.
18. Tri1sooctylamfne (TIOA), reagent grade.
19. TIOA solutfon fn p-xylene, 10 percent. Dissolve 100 ml of
triisooctylamine in p-xylene and dilute to 1 liter with p-xylene.
20. p-Xylene, reagent grade.
21. Thorium-234 tracer solution, approximately 800 pCi/ml, accurately
calibrated.
22. Uranium-232 tracer solution, approximately 1 pCi/ml, accurately
calibrated.
00-07-2
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Sample Preparation
1. Filter water sample of one to four liters through a pleated
filter.
2. Add 50 ml 12M HC1 and measured aliquots of 234Th and 232U
tracers.
3. Evaporate sample to 200 ml volume.
4. Add 600 ml of 12M HC1 to make sample concentration 9F4 in HC1.
Uranium Determination
1. Place 100 ml of 10 percent TIOA solution in a 1 liter separatory
funnel. Add 50 ml 9M HC1 and shake funnel for one minute. Drain
and discard lower aqueous acid phase after clean separation of
the two phases.
2. Add the aqueous acid sample to the TIOA in the separatory funnel
and shake the funnel vigorously for two minutes. Vent the funnel
stopcock to prevent pressure buildup in the funnel.
3. Allow the phases to separate cleanly and draw off the lower
aqueous acid phase. Save for thorium analysis.
4. Add 50 ml 9f1 HC1 to the TIOA solution in the separatory funnel
and shake for one minute.
5. Allow the phases to separate; withdraw and discard lower aqueous
-• acid phase.
6. Repeat steps 4 and 5.
7. Strip the uranium from the TIOA solution by adding 100 ml
0.1M HN03 to the separatory funnel and shaking the funnel for
two minutes.
8. Allow phases to separate; withdraw and save lower acid phase.
9. Repeat steps 7 and 8 and combine strip solutions. Discard TIOA
solution.
10. Place combined strip solutions in the clean separatory funnel.
11. Add 100 ml p-xylene to combined strip solution and shake funnel
for one minute. See Note 3.
00-07-3
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12. Allow phases to separate cleanly; withdraw lower aqueous add
layer Into beaker. Discard p-xylene.
13. Evaporate combined solution from step 12 to dryness. Do not
overheat.
14. Add 100 ml 16M HN03 to residue and evaporate to dryness. Do
not overheat.
15. Add 5 ml 9ri HC1 and 5ml 12M HCIO^ to residue and evaporate to
dryness.
16. Repeat step 15.
17. Add 10 ml 12M HC1 and evaporate to dryness.
18. Repeat step 17.
19. Add 50 ml 1M HC1 to sample residue and warm gently to dissolve
residue.
20. Heat sample solution to 80°C with stirring and add 50 mg ascorbic
acid. Do not overheat.
21. Suspend clean nickel metal strip into solution for two hours to
remove polonium.
22. Remove nickel and evaporate solution to dryness.
23. Add 15 ml M HC1 to sample residue and warm to approximately 50°C.
24. Add enough ascorbic acid to reduce iron in the sample, indicated
by the disappearance of yellow color.
25. Add 1 ml of 0.4 percent TiClj to reduce uranium.
26. Add 1 ml of lanthanum carrier and 5 ml of 3M HF to precipitate
LaF, carrying uranium. Mix well and set aside for 30
minutes.
27. Using suction, filter coprecipltated sample through a filter
membrane.
28. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml etnano! and add to funnel.
29. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
00-07-4
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30. Mount membrane carefully on 32 mm planchet using double stick
tape.
31. Count sample for 1000 minutes on alpha spectrometer.
Thorium Determination
1. Evaporate aqueous add fraction containing thorium from step 3 of
Uranium Determination.
2. Add 10 ml 16M HM03 and evaporate to dryness.
3. Add 5 ml 9M HC1 and 5 ml 12M HC104 and evaporate to dryness.
4. Add 10 ml of 16f1 HNO, and evaporate to dryness.
5. Repeat step 4.
6. Dissolve sample in 10 ml of 6f1 HIJOj with heat.
7. Prepare ion exchange column with 25 ml BioRad AG1X8. resin. Wash
resin with 250 ml of 6M HN03.
8. Decant sample into column at gravity flow (approx. 3ml/min) and
rinse the sample on the column with an additional 50 ml of 6f1
HNOj. Discard wash.
9. Elute the thorium from the column with 200 ml of 6M^ HC1 at flow
rate of 3 ml/minute.
10. Evaporate thorium eluate to dryness.
11. Add 10 ml 12M HC1 to residue and evaporate to dryness.
12. Add 15 ml 1M_ HC1 to sample residue and warm to approximately 50°C.
13. Add 1 ml lanthanum carrier and 5 ml of 3M HF. Mix well and set
aside for 30 minutes.
14. Using suction, filter copreclpitated sample through a filter
membrane.
15. Rinse sample beaker with 10 ml water and add to filter funnel.
Rinse beaker with 10 ml ethanol and add to funnel.
16. Remove clamp and top of funnel with suction on. Allow membrane
to dry.
17. Mount membrane carefully on 32 mm planchet using double stick
tape.
00-07-5
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18. Beta count the sample to measure thorlum-234 recovery.
19. Count sample for 1000 minutes on alpha spectrometer.
Calculations
Calculate the concentration, Z, of uranium In plcocuries per liter as
follows:
z _ (A-Aj) x F
where
E
F
V
T
2.22
gross sample counts which appear In the uranium-234,-235,
or-238 alpha energy region,
background counts in the same alpha energy region as A above*
gross tracer counts which appear in the alpha energy region
of the tracer isotope,
background counts in the same alpha energy region as B_ above,
alpha detector efficiency,
total calibrated tracer counts for same counting time as
sample counts,
sample volume (liters),
counting time (minutes), and
dpm per pCi.
Calculate the concentration, Z, of thorium In picocuries per liter as
follows:
, (A - A,) x F
(2.22HB - BjHEHVHT)
00-07-6
-------
where
A = gross sample counts which appear in the thorium -227, -228,
-230 or -232 alpha energy region,
A. s background counts in the same alpha energy region as AL above,
B = gross tracer beta counts,
Bj 8 beta counter background,
E 8 alpha detector efficiency,
F 8 total calibrated tracer beta counts,
V = sample volume (liters),
T 8 counting time (minutes), and
2.22 8 dpm per pCi.
Calculate the lower limit of detection (LLD) for thorium in
picocurles per liter as follows:
4.66 V CRT
LLD
(2.22)(E)(R)(W)(T)
where
CB = background count rate,
T = counting time (same for sample and background),
E = alpha detector efficiency,
R = fractional yield based on B-Bj/F in calculation,
Y = sample volume (liters), and
2.22 = dpm per pCi.
This LLD calculation is valid if the sample counting time is the same
as the background counting time.
00-07-7
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Notes
1. Nuclepore is a registered trademark of Nuclepore Corp., Pleasanton, CA.
2. Teflon Is a registered trademark of Dupont, Co., Wilmington, DE.
3. The p-xylene removes most of the TIOA carried into the aqueous acid
phase. Residual TIOA makes the coprecipitation step more difficult.
References
1. Moore, F.L., "Liquid-Liquid Extraction of Uranium and Plutonium from
Hydrochloric acid Solution with Tri (iso-octyl) amine," Analytical
Chemistry 30. 908 (1958).
00-07-8
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