1、Designation: C 1387 03Standard Guide forthe Determination of Technetium-99 in Soil1This standard is issued under the fixed designation C 1387; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p
2、arentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This document is intended to serve as a reference forlaboratories wishing to perform Tc-99 analyses in soil. Severaloptions are given for selecti
3、on of a tracer and for the method ofextracting the Tc from the soil matrix. Separation of Tc fromthe sample matrix is performed using an extraction chroma-tography resin. Options are then given for the determination ofthe Tc-99 activity in the original sample. It is up to the user todetermine which
4、options are appropriate for use, and togenerate acceptance data to support the chosen procedure.1.2 Due to the various extraction methods available, varioustracers used, variable detection methods used, and lack ofcertified reference materials for Tc-99 in soil, there is insuffi-cient data to suppor
5、t a single method written as a standardmethod.2. Referenced Documents2.1 ASTM Standards:C 998 Sampling Surface Soil for Radionuclides2C 999 Soil Sample Preparation for the Determination ofRadionuclides2D 1193 Standard Specification for Reagent Water3E 11 Specification for Wire-cloth Sieves for Testi
6、ng Pur-poses43. Summary of Guide3.1 There are no stable isotopes of technetium.Technetium-99 is produced by the fission of uranium andplutonium, and has been released to the environment vianuclear weapons testing and nuclear materials processing. Inan oxidizing environment, it exists as the very mob
7、ile pertech-netate ion, TcO4. Technetium-99 is a long-lived (half-life213,000 years), weak beta (beta max of 293 keV) emittingradioisotope.3.2 For the analysis of Tc-99 in soil, a tracer is added to thesample matrix, or spiked duplicate samples are prepared, andthen the Tc is extracted from the soil
8、 matrix by one of severalmethods, including acid leaching or one of various fusionmethods. The resulting solution is passed through an extractionchromatography column. Technetium is known to be retainedby the extraction chromatography material while most otherelements pass through the column. The co
9、lumn is washed withdilute acid to remove any remaining interferents. The resinmay then be counted directly by adding it to a liquid scintil-lation cocktail and counting by liquid scintillation spectrom-etry, or the Tc may be eluted from the resin for alternativecounting or mass spectrometric techniq
10、ues.4. Significance and Use4.1 This guide offers several options for the determinationof Tc-99 in soil samples. Sample sizes of up to 200 g arepossible, depending on the method chosen to extract Tc fromthe soil matrix. It is up to the user to determine if it isappropriate for the intended use of the
11、 final data.5. Interferences5.1 Any radionuclide not completely removed by the ex-traction chromatography column that has a beta decay energysimilar to or higher than Tc-99 will interfere when countingtechniques are used for quantification of the Tc-99 activity.5.2 Any elements with a mass-to-charge
12、 ratio (m/z) of 99(that is, naturally occurring isotope of Ru-99, or other artifi-cially produced elements of sufficient half-life with similarm/z) can interfere when using mass spectrometry for quantifi-cation of the Tc-99 activity. Any element with the same m/z asthe isotope used as an isotope dil
13、ution tracer or internalstandard will cause a bias in the yield correction. Correctionsshould be included in the mass spectrometry data reduction forknown interferences.5.3 Additional interferences may be encountered, depend-ing on the tracer and measurement technique chosen. It is up tothe user to
14、determine and correct for any additional interfer-ences.6. Apparatus6.1 Apparatus for the Extraction of Tc from Sample Matrix:6.1.1 See the individual extraction method descriptions tocompile a list of the equipment needed for the chosen extrac-tion method.1This guide is under the jurisdiction of AS
15、TM Committee C26 on Nuclear FuelCycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved July 10, 2003. Published August 2003. Originallyapproved in 1998. Last previous edition approved in 1998 as C 138798.2Annual Book of ASTM Standards, Vol 12.01.3An
16、nual Book of ASTM Standards, Vol 11.01.4Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Apparatus for the Purification of Tc from the SoilExtract:6.2.1 Extraction columnwith a bed volume o
17、f severalmilliliters for the extraction chromatography resin.56.2.2 Column extension funnelsthat can be added to theextraction column such that a few hundred milliliters ofsolution can be added to the column at one time.6.2.3 Column rackto hold columns such that severalextractions can be performed s
18、imultaneously.6.3 Apparatus for the Quantification of Tc-99:6.3.1 See the individual detection method descriptions tocompile a list of the equipment needed for the chosen detectionmethod.7. Reagents7.1 Purity of ReagentsAll chemicals should, at a mini-mum, be of reagent grade and should conform to t
19、he specifi-cations of the Committee on Analytical Reagents of theAmerican Chemical Society where such specifications areavailable.6High Purity reagents are suggested if mass spec-trometry is chosen as the detection method. Other grades ofreagents may be used provided it is first determined that ther
20、eagent is of sufficient purity to permit its use without lesseningthe accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water, as definedby Type I of Specification D 1193.7.3 Tracer:7.3.1 Isotope Dilution Yield Determi
21、nation:7.3.1.1 Radiometric Yield Determination Tc-95m7or Tc-99m8have been used to monitor the chemical yield of theextraction and purification of Tc-99 prior to quantification.Example: Add 10 nCi of Tc-99m as a yield tracer whendetermining yield by gamma spectrometry.7.3.1.2 Mass Spectrometric Yield
22、 DeterminationTc-97may be produced in a nuclear reactor in very limited quantitiesto be used as an isotope dilution tracer for the mass spectro-metric determination of Tc-99 (1).9Example: Add 1 ng ofTc-97 as a yield tracer for mass spectrometry.7.3.2 Duplicate Sample Analysis to Monitor Chemical Yie
23、ld:7.3.2.1 Duplicate samples may be analyzed, one spiked witha known amount of Tc-99 and one unspiked. The chemicalrecovery of the spiked sample is then used to correct theunspiked sample to obtain the original sample activity.7.4 Reagents for the Extraction of Tc-99 from SampleMatrix:7.4.1 See the
24、individual extraction method descriptions tocompile a list of the reagents needed for the chosen extractionmethod.7.5 Reagents for the Purification of Tc from the SampleMatrix:7.5.1 Extraction Chromatrography Resin TEVA Resin.107.5.2 Prefilter Resina nonionic acrylic ester polymer resinused to remov
25、e residual organic matter prior to the extractionchromatography resin column.117.5.3 Hydrogen Peroxide30 %.7.5.4 Nitric Acid(HNO3) concentrated, specific gravity1.42.7.5.5 1M Nitric AcidAdd 63 mL of high purity HNO3to900 mL of DI water, dilute to a final volume of 1 liter.7.5.6 4M Nitric AcidAdd 250
26、 mL of high purity HNO3to600 mL of DI water, dilute to a final volume of 1 liter.7.6 Reagents for the Quantification of Tc-99:7.6.1 See the individual detection method descriptions tocompile a list of the reagents needed for the chosen detectionmethod.8. Procedure8.1 Collect samples in accordance wi
27、th Specification C 998.8.2 Soil or Sediment Preparation:8.2.1 Oven dry samples at a temperature not to exceed105C and homogenized in accordance with SpecificationC 999.8.2.2 OptionalSamples may be placed in a muffle oven todecompose organic matter prior to the extraction of Tc. Themuffling technique
28、s reported vary significantly (2-4).Ifde-sired, it is suggested that 510 g of the sample be weighed ina high temperature crucible. Add the chosen yield monitor andmix the sample. Wet the sample with concentrated ammoniumhydroxide and mix, then dry under a heat lamp. It has beenfound that ammonium hy
29、droxide will prevent the loss of thevolatile Tc at higher temperatures. Place the sample in a muffleoven for 24 hours at 500C (4), or for 3060 minutes at 600Cfollowed by the addition of a few grams of ammonium nitrateand 10 more minutes of heating if traces of carbon remain (2).8.3 Tc Extraction The
30、se discussions are summaries fromavailable literature. The user must read the primary referencefor a complete discussion of the method prior to its use.8.3.1 Acid Leaching There are many reported acid leach-ing techniques in the literature (2, 3, 5-9); however, only thosethat are easily coupled to t
31、he extraction chromatographypurification are described in 8.3.1.1-8.3.1.4. These methods aresummarized in the following four sections8.3.1.1 Weigh out up to 10 grams of soil to a 250 mL glassbeaker along with the desired yield monitor. Cover and heat thesample in the presence of 1M nitric acid. Afte
32、r cooling, removeresidual solid matter from the sample by centrifugation. Add5Prepacked columns from EIChroM Technologies (Darien, IL) or BioRad(Richmond, CA) poly prep columns have been found satisfactory for this purpose.6Reagent Chemicals, American Chemical Society Specifications, AmericanChemica
33、l Society, Washington, D. C. For suggestions on the testing of reagents notlisted by the American Chemical Society, Washington, D. C. For suggestions on thetesting of reagents not listed by the American Chemical Society, see AnalarStandards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U. K., a
34、nd theUnited States Pharmacopeia and National Formulary, U.S. Pharmaceutical Con-vention (USPC), Rockville, MD.7Tc-95m may be obtained from Analytics, Inc., Atlanta, GA, or other suitablesupplier.8Tc-99m may be obtained from a local medical pharmacy supplier or othersuitable supplier.9The boldface n
35、umbers in parentheses refer to the list of references at the end ofthis standard.10TEVA Resin from EIChroM Technologies has been found satisfactory for thepurposes listed. No other commercial sources of equivalent material are known.11Prefilter columns are available from EIChroM Technologies or Ambe
36、rchromGC-71CD resin has been found satisfactory for this purpose.C 1387 032hydrogen peroxide and sodium vanadate to each sample todestroy residual organic matter. Finally, reduce the acidity ofthe sample to less than 0.5M using ammonium hydroxide(dilute with water to a final sample volume of approxi
37、mately500 mL) (5).8.3.1.2 Add the desired yield monitor to 510 g of sample,which is then ashed using step 8.2.2. Leach the sample twicewith hot 8M nitric acid and hydrogen peroxide, combining theleachates. Adjust the pH to 7 with sodium hydroxide and filterthe solution through a glass fiber filter.
38、Dilute the water toapproximately 500 mL (6).8.3.1.3 Weigh out up to 200 grams of sample. Add thedesired yield monitor. Ash using step 8.2.2. Transfer the sampleto a decomposition vessel. Add 6M nitric acid. Decompose thesample at 100120C for one hour. Filter the sample through aglass fiber filter th
39、en dilute with water until the acid concen-tration is less than 0.5M nitric acid (at least 500 mL) (7).8.3.1.4 Weigh out one gram of the dried, unashed sample toa 250 mL conical flask. Add the desired yield monitor. Addconcentrated nitric acid and fit into a reflux condenser. Refluxthe sample until
40、the brown fumes cease and all the organicmatter is dissolved. Cool the flask and pour the solution intowater. Neutralize the solution with sodium hydroxide, filter outany undissolved residue, and dilute to a final volume ofapproximately 250500 mL (8).8.3.2 Soil FusionThe following two methods have b
41、eenused for Tc-99.8.3.2.1 Weigh out four grams of sample. Add the desiredyield monitor and ash using step 8.2.2. When cool, transfer thesample to a Ni crucible. Add 20 gram of the flux mixture(Na2CO3,K2CO3and NaNO3in a 3.92:5.08:1.00 weight ratio;the flux-to-sample ratio should be 5:1). Start the fu
42、sion byheating the crucible with the sample over a burner at high heat.When no further reaction is visible, cover the crucible andplace in a muffle over set at 900C for 30 minutes. Remove thesample from the oven and cool. Cover the crucible with awatch glass and add about 25 mL of water to the cruci
43、ble tostart dissolving the cake. Transfer the solution to a beaker andcontinue rinsing the crucible with water until all the cake isrinsed into the beaker. Cover the beaker and warm slightly ifneeded to complete the dissolution. Dilute with water to a finalvolume of about 200250 mL (10).8.3.2.2 It i
44、s suggested that the sample be ground to passthrough a 45 micron standard test sieve as defined in Specifi-cation E 11. This will result in a homogeneous sample with aparticle size that can be attacked by the fusion procedure.Weigh out 0.25 gram of sample to a Zr crucible. Add thedesired yield monit
45、or. Add 2.25 gram of sodium peroxide andmix well. Place the crucible in a muffle oven preheated to470C. Heat for 30 minutes. Remove from the oven. Whencool, add about 40 mL of water. Allow the mixture to dissolvefor approximately one hour. Add 4 mL of concentrated nitricacid to the crucible and dilu
46、te the solution to a final volume ofapproximately 150200 mL with water (11).8.3.3 Microwave DigestionThe following two methodshave been used for Tc-99.8.3.3.1 Weigh out 0.5 gram of sample into a microwavedigestion vessel. Add the desired yield monitor to the vessel.Add 20 mL of 4M nitric acid to the
47、 bomb and swirl to mix thecontents. Place the bomb in a microwave and heat at moderatepower for 3060 minutes.12Let the vessels cool completelybefore venting and opening. Pour the solution to a beaker.Rinse the vessel with water and add to the sample beaker.Dilute to a final volume of 200250 mL such
48、that the final acidsolution is less than 0.5M (12).8.3.3.2 Weigh out up to 0.5 gram of sample to a tared Teflonliner. Add the desired yield monitor to each sample. Add 10 mLof concentrated nitric acid to each sample. Allow the samplesto predigest in the open vessel for at least 15 minutes. Place the
49、Teflon liners into the microwave digestion vessels and place inthe microwave oven13in accordance with the manufacturersspecifications. Heat the samples in stages up to a maximum of200C and 600 psi. Allow the samples to cool to less than 30psi and 80C. The vessels are manually vented and the samplesolution transferred to a labeled container with water. Anyundigested residue is removed by centrifugation. Dilute thefinal solution with water such that the final acid concentrationis less than 0.5M in nitric acid, about 350 mL (13).8.4 Tc Purification b
