ASTM D7168-05
(Test Method)Standard Test Method for99Tc in Water by Solid Phase Extraction Disk
Standard Test Method for<sup>99</sup>Tc in Water by Solid Phase Extraction Disk
SCOPE
1.1 This test method describes a solid phase extraction (SPE) procedure to separate 99Tc from environmental water samples (that is, non-process and effluent waters). Technetium-99 beta activity is measured by liquid scintillation spectrometry.
1.2 This test method is designed to measure 99Tc in the range of approximately 0.037 Bq/L (1.0 pCi/L) or greater for a one litre sample.
1.3 The values stated in SI units are to be regarded as standard. Values given in parentheses are provided for information purposes only.
1.4 This method has been used successfully with tap water. It is the user's responsibility to ensure the validity of this test method for samples larger than 1 L and for waters of untested matrices.
1.5 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. For specific hazard statements, see Section 9.
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Designation:D7168–05
Standard Test Method for
Tc in Water by Solid Phase Extraction Disk
This standard is issued under the fixed designation D 7168; 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 3. Terminology
1.1 This test method describes a solid phase extraction 3.1 Definitions—For definitions of terms used in this test
(SPE) procedure to separate Tc from environmental water method refer to Terminology D 1129.
samples (that is, non-process and effluent waters).
4. Summary of Test Method
Technetium-99 beta activity is measured by liquid scintillation
spectrometry. 4.1 Ameasuredaliquantofsampleistransferredtoabeaker.
Hydrogen peroxide is added to facilitate the formation of the
1.2 This test method is designed to measure Tc in the
range of approximately 0.037 Bq/L(1.0 pCi/L) or greater for a extractable pertechnetate ion. The sample may be heated to
oxidize organics if such are suspected to be present. The entire
one litre sample.
1.3 The values stated in SI units are to be regarded as sample is passed through a technetium-selective SPE disk onto
which the pertechnetate is adsorbed. The disk is transferred to
standard. Values given in parentheses are provided for infor-
mation purposes only. a liquid scintillation vial, cocktail added, and the contents well
mixed. The beta emission rate of the sample is determined by
1.4 This method has been used successfully with tap water.
It is the user’s responsibility to ensure the validity of this test liquid scintillation spectrometry. Chemical yield corrections
are determined by the method of standard additions.
method for samples larger than 1 L and for waters of untested
matrices. 4.2 Minor differences in processing between Extraction
Chromatographic Resin Discs and PTFE Membrane Disks are
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the addressed in Variations A and B of the method.
responsibility of the user of this standard to establish appro-
5. Significance and Use
priate safety and health practices and determine the applica-
5.1 This method has not been evaluated for all possible
bility of regulatory limitations prior to use. For specific hazard
matrices. Method suitability should be determined on specific
statements, see Section 9.
waters of interest.
2. Referenced Documents
2 6. Interferences
2.1 ASTM Standards:
6.1 Suspended materials must be removed by filtration or
D 1129 Terminology Relating to Water
centrifuging prior to processing the sample. Suspended par-
D 1193 Specification for Reagent Water
ticulate matter in the sample will be physically trapped in part
D 2777 Practice for Determination of Precision and Bias of
or in whole on or in the SPE extraction material.This may lead
Applicable Methods of Committee D19 on Water
topotentialinclusionofradionuclidebearingsolidsortosignal
D 3370 Practices for SamplingWater from Closed Conduits
quenching in the liquid scintillation measurement.
D 4448 Guide for Sampling Ground-Water Monitoring
6.2 Technetium-99 activity in the sample may overwhelm
Wells
the signal from the Tc spike addition and interfere with
D 5847 Practice for Writing Quality Control Specifications
accurate determination of chemical yield. Samples for which
for Standard Test Methods for Water Analysis
the unspiked sample count rate exceeds 50 % of the spiked
D 6001 Guide for Direct-Push Water Sampling for Geoen-
sample count rate should be reprepared with an appropriately
vironmental Investigations
adjusted aliquant and spike addition levels to minimize contri-
butions to uncertainty in the determination of the chemical
This test method is under the jurisdiction of ASTM Committee D19 on Water
yield.
andisthedirectresponsibilityofSubcommitteeD19.04onMethodsofRadiochemi-
6.3 Organic compounds present in significant quantities in
cal Analysis.
the sample may degrade the extraction performance of the SPE
Current edition approved June 1, 2005. Published June 2005.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
disk or may lead to elevated levels of quench during liquid
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
scintillation analysis. After the addition of hydrogen peroxide,
Standards volume information, refer to the standard’s Document Summary page on
the sample may be heated to destroy trace organic matter in the
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7168–05
sample. If organic components are present in the sample which 8.4 Technetium-Specific Solid Phase Extraction (SPE) Disks
may survive the peroxide digestion, these may be removed or Membranes (Extraction Chromatographic Resin Discs or
,
4 5
with an appropriate organic removal resin or disk (such as PTFE Membrane Disks ).
Amberchrom resin or disk) prior to passing the sample through 8.5 Hydrochloric Acid, 0.5M—Add 42 mL concentrated
the extraction chromatographic resin disc. HCl to 400 mL of reagent water. Dilute to 1 L with water.
6.4 The disk may retain tritium-labeled compounds. Setting 8.6 Nitric Acid, concentrated.
the Tc counting window above the maximum energy for the 8.7 Hydrogen Peroxide,30%.
tritium beta particle will eliminate potential tritium interfer- 8.8 Technetium-99 as pertechnetate in water or dilute base
ence. solution, traceable to a national standards body (such as NIST
6.5 Elevated levels of nitrates (> 10 000 ppm) will interfere in the U.S.).
with uptake of Tc. 8.9 Liquid Scintillation Cocktail—Commercially prepared
,
4 6
6.6 The higher energy region above the maximum energy LSC cocktail or equivalent.
for Tc should be monitored to help identify cases of signifi-
9. Hazards
cant actinide interference.
9.1 Use extreme caution when handling all acids. They are
6.7 Elevated levels of radionuclides present in anionic form
such as iodate, iron (III) and antimony may interfere with extremely corrosive, and skin contact could result in severe
burns.
measurement of technetium and lead to a positive bias in
sample results. Significantly elevated levels of actinides 9.2 When diluting concentrated acids, always use safety
glasses and protective clothing, and add the acid to the water.
(esp. Th decay progeny of uranium) when present in the
sample may cause a high bias in the reported Tc activity.
10. Sampling
Manufacturer specific recommendations about interferences
10.1 Collect a sample in accordance with Practice D 3370,
should be taken into consideration when determining the
D 4448 or D 6001.
applicability of this method for a given matrix.
11. Preservation
7. Apparatus
11.1 Preservation of samples being analyzed for Tc is not
7.1 Filtering Apparatus, 47-mm diameter filter apparatus as
required.
recommended by the SPE manufacturer.
11.1.1 Samples may be preserved by freezing. Allow
7.2 Liquid Scintillation Counter, with multiple energy re-
samples to come to ambient temperature prior to processing.
gion of interest (ROI) capabilities.
11.1.2 Samples may be processed if they have been previ-
7.3 Scintillation Vials, 20-mL vials, low potassium glass or
ously preserved to pH less than 2 with nitric or hydrochloric
plastic, exhibiting suitable optical reproducibility so as not to
acid. It is noted that high concentrations of nitric acid will
cause erratic results between samples.
adverselyaffectchemicalyield.Althoughyieldcorrectionswill
8. Reagents and Materials
correct for losses, better results may be obtained by using
unpreserved samples.
8.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
12. Calibration
all reagents shall conform to specifications of the Committee
12.1 Thefractionaldetectorefficiency(e )isdeterminedas
on Analytical Reagents of the American Chemical Society.
Tc
outlined in subsequent steps.
Other grades may be used, provided it is first ascertained that
12.1.1 Prepare triplicate calibration samples adding at least
the reagent is of sufficiently high purity to permit its use
20 Bq (~540 pCi) of traceable Tc in the pertechnetate form to
without lessening the accuracy of the determinations.
each of three 100 mL portions of reagent water. Each of the
8.2 Purity of Water—Unless otherwise indicated, references
three samples is processed using either method variation (Aor
towatershallbeunderstoodtomeanreagentwaterconforming
B), as appropriate.
to Specification D 1193, Type III.
8.3 Radioactive Purity—Radioactive purity shall be such
that the measured radioactivity of blank samples does not
The sole source of supply of the Eichrom TEVAt Discs known to the
exceed the calculated probable error of the measurement.
committee at this time is Eichrom Technologies, Inc., Darien, IL. If you are aware
of alternative suppliers, please provide this information to ASTM International
Headquarters.Your comments will receive careful consideration at a meeting of the
3 1
Reagent Chemicals, American Chemical Society Specifications, American responsible technical committee, which you may attend.
Chemical Society, Washington, DC. For suggestions on the testing of reagents not 3M Emporey Tc Rad Disks (3M, St. Paul, MN) have been found satisfactory
listed by theAmerican Chemical Society, see Annual Standards for Laboratory and for this purpose.
National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, Ultima Goldy LLT (Perkin Elmer Life and Analytical Sciences, 710 Bridge-
MD. portAvenue, Shelton, CT 06484-4794) has been found satisfactory for this purpose.
D7168–05
12.1.2 Collect the effluents from the three calibration as the spiked sample. (See section 6.2 for comment on
samples. Process the composited solution according to the appropriate spiking level.)
method to verify that greater than 99 % of the technetium was
13.1.4 Add 10 mL of 30 % H O to each sample while
2 2
retained by the SPE material in the calibration runs.
stirring.
12.1.3 An analyte-free aliquant of 100 mL reagent water is
13.1.5 If the presence of organic interferences is suspected,
also processed as a calibration or instrument blank.
heat the sample on a hotplate at approximately 80°C for about
12.1.4 Count the three vials containing the calibration
1 hour or until any visible reaction has subsided. Allow the
samplesandtheblankinaliquidscintillationcounterforatime sample to cool to ambient temperature before proceeding with
sufficient to amass greater than 10 000 counts for each of the
subsequent steps.
calibration standards.
13.1.6 Using forceps, carefully position a disc on the filter
12.1.5 Calculate the Tc Detector Efficiency (e ) for each
stand. Secure the funnel reservoir over the disc.
Tc
of the three vials:
13.1.7 Precondition the disc by allowing 25 mL of water to
pass through the disc by gravity.
R 2 R
g cb
e 5 (1)
Tc
A 13.1.8 Add the sample to the funnel reservoir and allow to
c
passthroughthediscbygravityflow(nominalflowrateshould
where:
not exceed ~100 mL/min).
R = gross count rate of the vial in the Tc count window
g
13.1.9 Rinse the disc with 25 mL of 0.5M HCl.
in counts per second,
13.1.10 Rinse the disc with 100 mL of water.
R = count rate of the calibration blank associated with
cb
13.1.11 Apply vacuum to the filtration apparatus to remove
the efficiency measurement in the Tc count win-
residual liquid from the disc.
dow in counts per second, and
A = activity of standard Tc added to each vial (Bq).
13.1.12 Detach the reservoir from the filter apparatus.
c
12.2 Calculate the average, e¯ , and the relative standard 13.1.13 Using forceps, remove and carefully roll the disc
Tc
deviation, s (e ), for the three efficiency values. The relative
and transfer to a scintillation vial.
r Tc
standard deviation of these parameters is used to estimate the
13.1.14 Add 15 mL of liquid scintillation cocktail.
–
13.1.15 Cap and shake the contents of the vial, to allow the
relative standard uncertainty of the average efficiency, u (e ),
r Tc
as follows: disc to disintegrate. A vortex mixer may be used.
13.1.16 Count the sample in a liquid scintillation counter
s ~e !
r Tc
–
using an optimized energy window within the range of 20 to
u ~e ! 5Π1 u ~A ! (2)
r Tc r c
292 keV for a period of time adequate to achieve the required
detection limit.
where:
u (A ) = relative standard uncertainty of the activity of 13.2 Method Variation B—For use with PTFE Extraction
r c
standard Tc added to each vial. Membranes:
12.3 Acalibration blank consisting of reagent water shall be 13.2.1 For each sample to be processed, transfer duplicate 1
processed and analyzed with each batch of samples to deter- L aliquants of sample to each of two beakers.
mine the background count rate in counts per second (R )tobe
13.2.2 Add a known quantity (~20 Bq) of traceable Tc
b
used for the calculation of sample results.
solution to the second aliquant of the sample which is labeled
as the spiked sample. (See section 6.2 for comment on
13. Procedure
appropriate spiking level.)
13.2.3 Add 10 mL of 30 % H O to each sample while
2 2
NOTE 1—To minimize the risk of cross-contamination while ensuring
stirring.
reproducibilitybetweenthesampleanditsspikedduplicate,eachaliquant-
spiked aliquant pair should be run simultaneously and in parallel, using
13.2.4 If the presence of organic interferences is suspected,
separate dedicated filtration apparatus.
heat the sample on a hotplate at approximately 80°C for
NOTE 2—The sample aliquant is typically 1 L but depending on the
approximately1houroruntilanyvisiblereactionhassubsided.
activity present and the required detection limit for the analysis, this may
Allow the sample to cool to ambient temperature before
vary from 0.1 to several litres.
proceeding with subsequent steps.
NOTE 3—A representative instrument blank (vial, cocktail and blank
13.2.5 Using forceps, carefully position a disk on the filter
disk) is counted with each batch to determine the background count rate
stand. Secure the funnel reservoir over the disk.
to be subtracted from each measurement (R in Eq 3). If the instrument
b
blank is to be reused, the user should determine its stability and shelf-life. 13.2.6 Connect the filtering apparatus to a vacuum source.
13.2.7 Pass the sample through the disk at a nominal flow
13.1 Method Variation A—For use with Extraction Chro-
rate of ~100 mL/min.
matographic Resin Discs:
13.2.8 Rinse the disk with 25 mL of 0.5M HCl.
13.1.1 Fo
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