ASTM C1310-95
(Test Method)Standard Test Method for Determining Radionuclides in Soils by Inductively Coupled Plasma-Mass Spectrometry Using Flow Injection Preconcentration
Standard Test Method for Determining Radionuclides in Soils by Inductively Coupled Plasma-Mass Spectrometry Using Flow Injection Preconcentration
SCOPE
1.1 This test method covers a procedure for measuring 99Tc and a procedure for measuring 230Th and 234U in soils. It is applicable to background soils and soils that have been contaminated by nuclear processes. It is intended as an alternative to radiochemical methods because it is faster, requires less labor, and produces less waste than many radiochemical methods.
1.2 Samples are dried, ground, dissolved by fusion, and analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). A sequential flow injection (FI) technique is used to provide lower detection limits than those obtained with direct aspiration into an ICP-MS, and, in the case of 99Tc, provides separation from interferences.
1.3 The 230Th and 234U procedure also would work for 232Th, 235U, and 238U, but the FI preconcentration usually is not required to measure these isotopes at the concentrations typically found in soils.
1.4 This test method is guided by quality control procedures derived from U.S. EPA procedures for inorganic analysis reported in SW-846 and the Contract Laboratory Program Statement of Work. The required level of quality control may vary between laboratories and projects. Laboratory statistical quality control procedures are required to ensure that this test method is reliable.
1.5 Becquerel (Bq) is the acceptable metric unit for radionuclide activity. However, picocurie (pCi) frequently is the unit used to express regulatory limits for radioactivity. The values stated in either of these units shall be regarded as standard. The values stated in each system may not be exact equivalents; therefore, each system must be used independently of the other, without combining values in any way.
1.6 Refer to Practice C998 for information on soil sample collection.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 1310 – 95
Standard Test Method for
Determining Radionuclides in Soils by Inductively Coupled
Plasma-Mass Spectrometry Using Flow Injection
Preconcentration
This standard is issued under the fixed designation C 1310; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.1 This test method covers a procedure for measuring Tc
230 234
priate safety and health practices and determine the applica-
and a procedure for measuring Th and U in soils. It is
bility of regulatory limitations prior to use.
applicable to background soils and soils that have been
contaminated by nuclear processes. It is intended as an
2. Referenced Documents
alternative to radiochemical methods because it is faster,
2.1 ASTM Standards:
requires less labor, and produces less waste than many radio-
C 998 Practice for Sampling Surface Soil for Radionu-
chemical methods.
clides
1.2 Samples are dried, ground, dissolved by fusion, and
C 1215 Guide for Preparing and Interpreting Precision and
analyzed by inductively coupled plasma-mass spectrometry
Bias Statements in Test Method Standards Used in the
(ICP-MS). A sequential flow injection (FI) technique is used to
Nuclear Industry
provide lower detection limits than those obtained with direct
99 D 1193 Specification for Reagent Water
aspiration into an ICP-MS, and, in the case of Tc, provides
E 11 Specification for Wire-Cloth Sieves for Testing Pur-
separation from interferences.
230 234 poses
1.3 The Th and U procedure also would work for
235 238
E 135 Terminology Relating to Analytical Chemistry for
232Th, U, and U, but the FI preconcentration usually is not
Metals, Ores, and Related Materials
required to measure these isotopes at the concentrations
2.2 U.S. EPA Standards:
typically found in soils.
SW-846, Test Methods for Evaluating Solid Waste
1.4 This test method is guided by quality control procedures
U.S. EPA Contract Laboratory Program Statement of Work
derived from U.S. EPA procedures for inorganic analysis
2 for Inorganic Analysis
reported in SW-846 and the Contract Laboratory Program
Statement of Work . The required level of quality control may
3. Terminology
vary between laboratories and projects. Laboratory statistical
3.1 Definition:
quality control procedures are required to ensure that this test
3.1.1 calibration—refer to Terminology E 135.
method is reliable.
3.2 Definitions of Terms Specific to This Standard:
1.5 Becquerel (Bq) is the acceptable metric unit for radio-
3.2.1 abundance sensitivity—the characteristic of a mass
nuclide activity. However, picocurie (pCi) frequently is the unit
spectrometer specifying the likelihood of a large peak produc-
used to express regulatory limits for radioactivity. The values
ing counts at an adjacent mass. It usually is expressed as the
stated in either of these units shall be regarded as standard. The
number of counts required in the large peak to produce one
values stated in each system may not be exact equivalents;
count at an adjacent mass.
therefore, each system must be used independently of the other,
3.2.2 analyte—an isotope whose concentration is being
without combining values in any way.
determined by the test method.
1.6 Refer to Practice C 998 for information on soil sample
3.2.3 calibration blank—a solution used to establish the
collection.
zero-concentration calibration point.
1.7 This standard does not purport to address all of the
3.2.4 calibration reference solution—a solution containing
known concentrations of the analytes used for instrument
This test method is under the jurisdiction of ASTM Committee C-26 on Nuclear
calibration.
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
Test.
Current edition approved Nov. 10, 1995. Published March 1996.
2 4
Third edition, revision 1, 1992. Available from the U.S. Government Printing Annual Book of ASTM Standards, Vol 12.01.
Office, Washington, DC 20402. Annual Book of ASTM Standards, Vol 11.01.
3 6
Document Number ILM01.0. Available from the CLP Sample Management Annual Book of ASTM Standards, Vol 14.02.
Office, P.O. Box 818, Alexandria, VA 22313. Annual Book of ASTM Standards, Vol 03.05.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 1310
3.2.5 continuing calibration blank check solution (CCB)—a 3.2.21 RDL check solution—a solution containing the ana-
solution prepared in the same way as the calibration blank that lytes at a concentration of approximately two times the RDL
is analyzed at regular intervals to determine if the zero point of that is analyzed to assess analytical performance near the RDL.
the calibration has changed significantly during the analytical 3.2.22 specific activity—of a radionuclide, the numerical
run. value used to convert between units of radioactivity and mass.
3.2.6 continuing calibration verification check solution It is derived from the half-life and the atomic mass of the
radionuclide and is expressed as disintegration rate per unit
(CCV)—a solution containing the analytes at half the concen-
trations in the calibration reference solution that is analyzed at mass.
3.2.23 sequential flow injection—an automated non-
regular intervals to verify the accuracy of the calibration
throughout the analytical run. chromatographic flow analysis technique for concentrating the
analytes and separating them from sample components by
3.2.7 duplicate specimen analysis—a second specimen that
reproducibly and sequentially manipulating flow of sample and
is treated the same as the original specimen to determine
reagents through a column of sorbent material and to the
precision of the test method.
nebulizer of an ICP-MS.
3.2.8 flow injection—see sequential flow injection.
3.2.24 serial dilution analysis—a digested specimen that is
3.2.9 initial calibration blank check solution (ICB)—the
diluted five-fold with calibration blank solution and analyzed
same as CCB except that it is analyzed immediately after the
as an indication of the effect of interferences.
ICV.
3.2.25 spiked specimen analysis—a specimen to which a
3.2.10 initial calibration verification check solution
known amount of analyte is added prior to sample dissolution
(ICV)—a solution containing known concentrations of the
that is analyzed to detect bias of the test method.
analytes obtained from a source other than that of the calibra-
tion reference solution that is analyzed to verify the accuracy of
4. Summary of Test Method
the calibration.
4.1 The analysis system consists of a computer-controlled
3.2.11 interference check solution, part A (ICSA)—a solu-
FI system attached to the nebulizer of an ICP-MS. The FI
tion containing known concentrations of interfering substances
system concentrates the analytes by solid-phase extraction and,
that is analyzed to verify that accurate results can be obtained
in the case of Tc, provides separation from interferences. The
for a solution that does not contain analyte but contains a
ICP-MS nebulizes the FI eluent into a radio frequency-
relatively high level of interferences.
supported argon plasma that produces, ideally, singly-charged
3.2.12 interference check solution, part B (ICSAB)—the
atomic ions that are detected by mass spectrometry. Quadru-
same as ICSA, except that it contains known concentrations of
pole mass spectrometers are most commonly used.
the analytes.
4.2 Soil samples are dried, ground, and blended to achieve
3.2.13 instrument detection limit (IDL)—the concentration
homogeneity. For Tc analysis, samples are fused with sodium
of the analyte equivalent to three times the standard deviation
230 234
peroxide and dissolved in nitric acid. For Th and U
of ten replicate measurements of the calibration blank.
analysis, samples are fused with lithium metaborate and
3.2.14 internal standard—an element or isotope that is not
dissolved in nitric acid.
expected to occur naturally in samples and is added to all
4.3 Sample solutions are analyzed as follows. Internal
sample solutions to serve as a reference to correct for instru-
standards are added and sample solutions are loaded into the
ment drift and varying chemical recovery through the FI
229 233
automated sampler of the FI system. Rhenium, Th, and U
concentration step. 99 230 234
are used as internal standards for Tc, Th, and U,
3.2.15 laboratory control sample (LCS)—a homogeneous
respectively. The computer starts the FI program and signals
soil sample containing known concentrations of the analytes
the ICP-MS to read during the elution step. The ion intensity
that is analyzed to verify the accuracy of the test method.
measured at the atomic mass of the analyte, normalized to the
3.2.16 linear range—the concentration range over which
intensity of the internal standard, is proportional to the con-
the analyte signal is linear with respect to its concentration
centration of the analyte in the sample solution. The system is
within an established limit.
calibrated by analyzing solutions with known analyte concen-
3.2.17 linear range check solution (LRS)—a solution con-
trations and calculating a calibration equation by regression
taining known concentrations of the analytes that is used to
analysis using the known concentrations and the normalized
determine the upper limit of the linear range.
ion intensities. Sample results are calculated by applying the
3.2.18 preparation blank (PB)—a sample consisting of all
calibration equation to the normalized ion intensity of the
the reagents used for sample preparation that is carried through
analyte measured in the sample.
the dissolution and analytical processes to determine if con-
4.4 The analysis time for a specimen solution is 3.5 min and
tamination is introduced by the processes.
a 10-mL portion of specimen solution is consumed in each
3.2.19 relative standard deviation (RSD)—is expressed in
analysis.
this standard as a percentage, and is calculated by multiplying
5. Significance and Use
by 100 the standard deviation of a data set divided by the mean
of the data set.
5.1 The test methods in this standard may be used to
99 230 234
3.2.20 required detection limit (RDL)—the instrument de- measure the concentrations of Tc, Th, and U in soil
tection limit that must be achieved to meet the requirements of samples. The test methods are applicable to soils that have been
the project for which samples are analyzed by this test method. contaminated by nuclear-related activities such as uranium ore
C 1310
processing and uranium enrichment. The FI concentration step tion of Th in the samples and the abundance sensitivity of
reduces detection limits by approximately a factor of ten the ICP-MS in use.
compared to ICP-MS with conventional sample introduction.
6.1.2.2 The potential for interference should be determined
Approximate IDLs are listed in Table 1.
for each ICP-MS system used by measuring the count rate at
mass 230 produced by a series of Th standards covering the
6. Interferences
concentration range of Th anticipated in samples.
6.1.2.3 The potential for interference was determined for
6.1 The test methods contain mechanisms to identify and
two different ICP-MS systems. The abundance sensitivity of
control all interferences that normally are encountered. The
the ICP-MS having the better rejection of the 232 mass was
magnitude of the interferences can vary significantly with
approximately 30 to 50 times better than the other ICP-MS
different instruments. Interferences should be evaluated thor-
system. For the ICP-MS having poor rejection for mass 232,
oughly on each ICP-MS system used. A discussion of interfer-
232Th levels equivalent to 20 mg/kg and above produced
ence management for each analyte is provided in 6.1.1-6.1.3.6.
significant counts at mass 230. The interference scheme
6.1.1 Interference Management for Tc Analysis:
described in 6.1.2.4-6.1.2.6 was used. With the second ICP-
6.1.1.1 The measurement method is subject to interferences
MS, no interference was observed for Th levels equivalent
from Ru because the mass spectrometer cannot distinguish
99 99
to 500 mg/kg.
Tc from Ru. Ruthenium is a very rare element. The average
6.1.2.4 If Th is present at high enough concentration in a
abundance of ruthenium in the earth’s crust is on the order of
sample to tail into mass 230, it will also tail into mass 231.
1 ng/g. The natural abundance of Ru is 12.7 %. Naturally
Therefore, the counts observed at mass 231 during an analysis
occurring ruthenium is not expected to present a serious
give an indication of the concentration of Th in the sample.
problem because it is so scarce. Ruthenium-99 is also the stable
99 99
Monitoring mass 231 to indicate the Th concentration is
element to which Tc decays by beta-emission. However, Ru
preferable to monitoring mass 232 because the count rate at
resulting from Tc decay is also expected to be scarce because
99 99
mass 232 would be several million counts per second if the
the half-life of Tc is 212,000 years and Tc has only been
232Th concentration is high enough to cause an interference at
produced from fission for approximately 50 years.
mass 230.
6.1.1.2 High concentrations of molybdenum could cause an
6.1.2.5 A correction factor can be determined by measuring
interference if the Mo peak is large enough to overlap with
98 +
the ratio of counts at mass 230 to counts at mass 231 for a Th
mass 99 or if formation of MoH is significant. The magni-
standard at a concentration high enough to produce an inter-
tude of the interference depends on the concentration of
ference. The factor can be used to correct the counts at mass
molybdenum in the sample, the abundance sensitivity of the
+ +
230 based on the counts at mass 231. The correction factor
ICP-MS in use, and the ratio of MoH to Mo .
should be determined each day at the beginning and end of the
6.1.1.3 The extraction resin is effective at separating tech-
analysis run.
netium from ruthenium and molybdenum. The separation
6.1.2.6 The interference check solutions described in 9.3.4
efficiency varies slightly between extraction columns from
and 9.3.5 should be analyzed at the beginning and end of each
approximately 97 % to greater than 99.5 %.
analytical run to demonstrate that Th can be tolerated up to
6.1.1.4 The average abundance of molybdenum in the
the level present in th
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