**SW-846 Update V 9320 - 1 Revision 1 July 2014**  **METHOD 9320**

**RADIUM 228**

**SW-846 is not intended to be an analytical training manual. Therefore, method**  **procedures are written based on the assumption that they will be performed by analysts who are**  **formally trained in at least the basic principles o f chemical analysis and in the use of the subject**  **technology.**

**In addition, SW-846 methods, with the exception of required method use for the analysis**  **of method-defined parameters, are intended to be gu idance methods which contain general**  **information on how to perform an analytical procedu re or technique which a laboratory can use**  **as a basic starting point for generating its own de tailed standard operating procedure (SOP),**  **either for its own general use or for a specific pr oject application. Performance data included in**  **this method are for guidance purposes only and must not be used as absolute quality control**  **(QC) acceptance criteria for purposes of laboratory QC or accreditation.** 

**1.0 SCOPE AND APPLICATION**

**Please see Appendix A at the back of this document for a summary of revisions to**  **Method 9320 (From Revision 0, September 1986).**

**1.1 This method covers the measurement of radium-2 28 in ground water and, if**  **desired, the determination of radium-226 on the sam e sample. If the level of radium-226 is**  **above 3 pCi/L, the sample must also be measured for radium-228.** 

**1.2 This technique is devised so that the beta act ivity from actinium-228, which is**  **produced by decay of radium-228, can be determined and related to the radium-228 that is**  **present in the sample.**

**1.3 To quantify actinium-228 and thus determine ra dium-228, the efficiency of the**  **beta counter for measuring the very short half-live d actinium-228 (avg. beta energy of 0.404**  **keV) is to be calibrated with a beta source of comp arable average beta energy.** 

**1.4 Analysts should consult the disclaimer stateme nt at the front of the manual and**  **the information in Chapter Two for 1) guidance on t he intended flexibility in the choice of**  **methods, apparatus, materials, reagents, and suppli es; 2) the responsibilities of the analyst for**  **demonstrating that the techniques employed are appr opriate for the analytes of interest, in the**  **matrix of interest, and at the levels of concern.**

**In addition, analysts and data users are advised t hat, except where explicitly specified in**  **a regulation, the use of SW-846 methods is** not **mandatory in response to Federal testing requirements. The information contained in this me**  **thod is provided by the Environmental Protection Agency (EPA) as guidance to be used by t**  **he analyst and the regulated community in making judgments necessary to generate results that**  **meet the data quality objectives for the intended application.** 

**1.5 This method is restricted to use by, or under supervision of, properly experienced**  **and trained personnel. Each analyst must demonstra te the ability to generate acceptable** 

**results with this method. SW-846 Update V 9320 - 2 Revision 1**  **July 2014 2.0 SUMMARY OF METHOD** 

**The radium in the water sample is collected by cop recipitation with barium and lead**  **sulfate and purified by reprecipitation from EDTA s olution. Both radium-226 and radium-228 are**  **collected in this manner. After a 36-hr ingrowth o f actinium-228 from radium-228, the actinium**  **228 is carried on yttrium oxalate, purified and bet a counted. If radium-226 is also desired, the**  **activity in the supernatant can be reserved for cop recipitation on barium sulfate, dissolving in**  **EDTA and storing for ingrowth in a sealed radon bub bler.** 

**3.0 DEFINITIONS**

**Refer to Chapter One, Chapter Three, and the manuf acturer’s instructions for definitions**  **that may be relevant to this procedure.**

**4.0 INTERFERENCES**

**4.1 Reagents, glassware, and other sample processi ng hardware may yield artifacts**  **and/or interferences during sample analysis. All o f these materials must be demonstrated to be** 

**free from interferences under the conditions of the analysis by analyzing method blanks.**  **Specific selection of reagents may be necessary. R efer to Chapter Three for general guidance**  **on glassware cleaning.**

**4.2 As evidenced by the results of the performance studies, the presence of**  **strontium-90 in the water sample gives a positive b ias to the radium-228 activity measured.**  **However, strontium-90 is not likely to be found in ground water, except possibly in monitoring** 

**wells around a radioactive burial site.**

**4.3 Excess barium in the water sample might result in a falsely high chemical yield.** 

**5.0 SAFETY**

**5.1 This method does not address all safety issues associated with its use. The**  **laboratory is responsible for maintaining a safe wo rk environment and a current awareness file**  **of OSHA regulations regarding the safe handling of the chemicals specified in this method. A**  **reference file of material safety data sheets (MSDS s) should be available to all personnel**  **involved in these analyses.**

**5.2 Personal protective equipment (PPE) should be w orn at all times when in the**  **laboratory. PPE requirements include chemical spla sh goggles and protective clothing and**  **gloves.**

**5.3 Acetic acid can cause severe skin and eye burns . The liquid and vapors are**  **flammable. Carefully follow handling and storage i nstructions found in its MSDS.** 

**5.4 Ammonium hydroxide is corrosive; carefully foll ow handling and storage instructions** 

**found in its MSDS. SW-846 Update V 9320 - 3 Revision 1**  **July 2014 6.0 EQUIPMENT AND SUPPLIES** 

**The mention of trade names or commercial products in this manual is for illustrative**  **purposes only, and does not constitute an EPA endor sement or exclusive recommendation for**  **use. The products and instrument settings cited in SW-846 methods represent those products**  **and settings used during method development or subs equently evaluated by the Agency.**  **Glassware, reagents, supplies, equipment, and setti ngs other than those listed in this manual**  **may be employed provided that method performance ap propriate for the intended application** 

**has been demonstrated and documented.**

**This section does not list all common laboratory g lassware (e.g., beakers and flasks)**  **that might be used.**

**6.1 Gas-flow proportional counting system (low-bac kground beta <3 cpm).** 

**6.2 Electric hot plate.**

**6.3 Centrifuge.**

**6.4 Membrane filters: Matricel 47-mm.**

**6.5 Drying lamp.**

**6.6 Stainless steel counting planchets.**

**6.7 Analytical balance.**

**7.0 REAGENTS AND STANDARDS**

**7.1 Reagent-grade chemicals, at a minimum, should be used in all tests. Unless**  **otherwise indicated, all reagents conform to the sp ecifications of the Committee on Analytical**  **Reagents of the American Chemical Society, where su ch specifications are available. Other**  **grades may be used, provided it is first ascertaine d that the reagent is of sufficiently high purity**  **to permit its use without lessening the accuracy of the determination.** 

**7.2 Reagent water -- Reagent water must be interfe rence free. All references to**  **water in this method refer to reagent water unless otherwise specified.** 

**7.3 Acetic acid (17.4 N), glacial CH 3**  **COOH (concentrated) sp. gr. 1.05, 99.8%.**

**7.4 Ammonium hydroxide (15 N), NH 4**  **OH (concentrated) sp. gr. 0.90, 56.6%.**

**7.5 Ammonium oxalate (5%): Dissolve 5 g (NH 4**  **) 2**  **C 2**  **O 4**  **• H 2**  **O in reagent water and**

**dilute to 100 mL.**

**7.6 Ammonium sulfate (200 mg/mL): Dissolve 20 g ( NH**  **4 )**  **2 SO**  **4 in reagent water and** 

**dilute to 100 mL.**

**7.7 Ammonium sulfide (2%): Dilute 10 mL (NH 4**  **) 2**  **S (20-24%), to 100 mL with reagent**

**water.**

**7.8 Barium carrier (16 mg/mL), standardized: Diss olve 2.846 g BaCl**  **2 • 2H**  **2 O in**  **reagent water, add 0.5 mL 16 N HNO 3**  **, and dilute to 100 mL with Type II water. SW-846 Update V 9320 - 4 Revision 1**  **July 2014 7.9 Citric acid (1 M): Dissolve 19.2 g C**  **6 H**  **8 O**  **7 • H**  **2 O in reagent water and dilute to** 

**100 mL.**

**7.10 EDTA reagent, basic (0.25 M): Dissolve 20 g NaOH in 750 mL reagent water,**  **heat, and slowly add 93 g disodium ethylenedinitril oacetate dihydrate (Na**  **2 C**  **10 H**  **14 O**  **8 N**  **2 • 2H**  **2 O)**  **while stirring. After the salt is in solution, fil ter through coarse filter paper, and dilute to 1 li**  **ter.**

**7.11 Lead carrier (15 mg/mL): Dissolve 2.397 g Pb (NO**  **3 )**  **2 in reagent water, add 0.5** 

**mL 16 N HNO 3**  **, and dilute to 100 mL with reagent water.**

**7.12 Lead carrier (1.5 mg/mL): Dilute 10 mL lead carrier (15 mg/mL) to 100 mL with**  **reagent water.**

**7.13 Standard strontium-89 tracer solution.**

**8.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE**

**Sample collection, preservation, and storage requi rements may vary by EPA program**  **and may be specified in a regulation or project pla nning document that requires compliance**  **monitoring for a given contaminant. Where such req uirements are specified in the regulation,**  **follow those requirements. In the absence of speci fic regulatory requirements, use the following**  **information as guidance in determining the sample c ollection, preservation, and storage**  **requirements.**

**8.1 All samples must have been collected in a mann er which addresses the**  **considerations discussed in Chapter Nine of the SW- 846 manual.** 

**8.2 It is recommended that samples be preserved at the time of collection by adding**  **enough 1 N HNO 3**  **to the sample to bring it to pH 2 (15 mL 1 N HNO 3**  **per liter of sample is usually sufficient). If samples are to be collecte**  **d without preservation, they should be brought to the laboratory within 5 days, then preserved, an**  **d held in the original container for a minimum of 16 hr before analysis or transfer of the sample.**  **See also Note to Paragraph 7.2 below.**

**8.3 All sample containers must be prewashed with a cids, water, and metal-free**  **detergents, if necessary, depending on the use hist ory of the container. For further information**  **see Chapter Three.**

**8.4 The container choice should be plastic (rather than glass) to prevent loss due to**  **breakage during transportation and handling.**

**9.0 QUALITY CONTROL**

**9.1 Refer to Chapter One for guidance on quality a ssurance (QA) and QC protocols.**  **When inconsistencies exist between QC guidelines, m ethod-specific QC criteria take**  **precedence over both technique-specific criteria an d Chapter One criteria; technique-specific**  **QC criteria take precedence over Chapter One criter ia. Any effort involving the collection of**  **analytical data should include development of a str uctured and systematic planning document,**  **such as a Quality Assurance Project Plan (QAPP) or a Sampling and Analysis Plan (SAP),**  **which translates project objectives and specificati ons into directions for those that will implement**  **the project and assess the results. SW-846 Update V 9320 - 5 Revision 1**  **July 2014 Each laboratory should maintain a formal quality a**  **ssurance program. The laboratory should also maintain records to document the qualit**  **y of the data generated. Development of in house QC limits for each method is encouraged. Use**  **of instrument specific QC limits is encouraged, provided such limits will generate data**  **appropriate for use in the intended application. All data sheets and quality control d**  **ata should be maintained for reference or inspection.** 

**9.2 Initial demonstration of proficiency (IDP).**

**The initial demonstration of method proficiency mus t be performed prior to independently**  **running an analytical method, and should be repeate d if other changes occur (e.g., instrument**  **repair, significant change in procedure, and change in analyst). An IDP must consist of**  **replicate reference samples from each sample prepar ation and determinative method**  **combination it utilizes by generating data of accep table accuracy and precision for target**  **analytes in a clean reference matrix taken through the entire preparation and analysis.** 

**9.3 Sample QC for preparation and analysis**

**The laboratory must also have procedures for docume nting the effect of the matrix on**  **method performance (precision, bias, and sensitivit y). At a minimum, this should include the**  **analysis of QC samples including a method blank, a matrix spike (MS), a laboratory control**  **sample (LCS), and a duplicate sample in each analyt ical batch. Any method blanks, LCS, MS**  **samples, and duplicate samples should be subjected to the same preparatory and instrument**  **determination procedures as those used on actual sa mples (see Sec. 11.0).** 

**10.0 CALIBRATION AND STANDARDIZATION**

**Counter efficiency: The beta counter may be calib rated with actinium-228 or strontium**  **89 (t 1/2**  **= 51 d). Strontium-89 has an average beta energy of 0.589 KeV. A standard strontium** 

**89 tracer solution can be used to determine beta ef ficiencies over a range of precipitate weights**  **on the stainless steel planchet.**

**11.0 PROCEDURE**

**11.1 For each liter of water add 5 mL 1 M C 6**  **H 8**  **C 7**  **• H 2**  **O and a few drops of methyl orange indicator. The solution should be red.** 

**NOTE : At the time of sample collection add 2 mL 16 N H**  **NO 3**  **for each liter of water.**

**11.2 Add 10 mL lead carrier (15 mg/mL), 2 mL stron tium carrier (10 mg/mL), 2.0 mL**  **barium carrier (16 mg/mL), 1 mL yttrium carrier (18 mg/mL) and stir well. Add 15 N NH**  **4 OH until**  **a definite yellow color is obtained; then add a few drops excess. Heat to incipient boiling and**  **maintain at this temperature for 30 min.**

**11.3 Precipitate lead and barium sulfates by addin g 18 N H**  **2 SO**  **4 until the red color**  **reappears. Then add 0.25 mL excess. Add 5 mL (NH 4**  **) 2**  **SO 4**  **(200 mg/mL) for each liter of sample. Stir frequently and keep at a temperature**  **of about 90°C for 30 min.**

**11.4 Cool slightly; then filter with suction throu gh a 47-mm matricel membrane filter**  **(GA6, 0.45-micron pore size). Make a quantitative transfer of precipitate to the filter by rinsing**  **last particles out of beaker with a strong jet of w ater.** **SW-846 Update V 9320 - 6 Revision 1 July 2014**  **11.5 Carefully place filter with precipitate in th e bottom of a 250-mL beaker. Add** 

**about 10 mL 16 N HNO 3**  **and heat gently until the filter completely dissol ves. Transfer the**  **precipitate into a polypropylene centrifuge tube wi th an additional 16 N HNO**  **3 . Centrifuge and**  **discard supernatant.**

**11.6 Wash the precipitate with 15 mL 16 N HNO 3**  **, centrifuge, and discard supernatant. Repeat this washing a second time.** 

**11.7 Wash the precipitate with 10 mL reagent water , centrifuge, and discard**  **supernatant.**

**11.8 Add 25 mL basic EDTA reagent, heat in a hot-w ater bath, and stir well. Add a**  **few drops 10 N NaOH if the precipitate does not rea dily dissolve.** 

**11.9 Add 1 mL strontium-yttrium mixed carrier and stir thoroughly. Add a few drops**  **10 N NaOH if any precipitate forms.**

**11.10 Add 1 mL (NH 4**  **) 2**  **SO 4**  **(200 mg/mL) and stir thoroughly. Add 17.4 N aceti c acid**  **until the barium sulfate precipitates. Then add 2 mL excess. Digest in a hot water bath until**  **precipitate settles. Centrifuge and discard supern atant.** 

**11.11 Add 20 mL basic EDTA reagent, heat in a hot- water bath, and stir until precipitate**  **dissolves. Repeat steps 7.9 and 7.10. (Note time of last barium sulfate precipitation as this is**  **the beginning of the actinium-228 ingrowth time.)**

**11.12 Dissolve the precipitate in 20 mL basic EDTA reagent as before; then add 1.0 mL**  **yttrium carrier (9 mg/mL) and 1 mL lead carrier (1. 5 mg/mL). If any precipitate forms, dissolve**  **by adding a few drops 10 N NaOH. Cap the polypropy lene tube and age at least 36 hr.** 

**11.13 Add 0.3 mL (NH 4**  **) 2**  **S and stir well. Add 10 N NaOH dropwise with vigor ous**  **stirring until lead sulfide precipitates. Then add 10 drops excess. Stir intermittently for about 10**  **min. Centrifuge and decant supernatant into a clea n tube.** 

**11.14 Add 1 mL lead carrier (1.5 mg/mL), 0.1 mL (N H**  **4 )**  **2 S and a few drops 10 N NaOH.**  **Repeat precipitation of lead sulfide as before. Ce ntrifuge and filter supernates through**  **Whatman #42 filter paper into a clean tube. Wash f ilter with a few mL water. Discard residue.** 

**11.15 Add 5 mL 18 N NaOH, stir well and digest in a hot water bath until yttrium**  **hydroxide coagulates. Centrifuge and decant supern ates into a beaker. Save for barium yield**  **determination (step 7.20). (Note time of yttrium h ydroxide precipitation as this is the end of the**  **actinium-228 ingrowth time and beginning of actiniu m-228 decay time.)** 

**11.16 Dissolve the precipitate in 2 mL 6 N HNO 3**  **. Heat and stir in a hot water bath about 5 min. Add 5 mL water and re-precipitate ytt**  **rium hydroxide with 3 mL 10 N NaOH. Heat and stir in a hot water bath until precipitate coag**  **ulates. Centrifuge and add this supernate to the supernate produced in step 7.15 in order to det**  **ermine barium yield.**

**11.17 Dissolve precipitate with 1 mL 1 N HNO 3**  **and heat in hot water bath a few minutes. Dilute to 5 mL and add 2 mL 5% (NH**  **4 )**  **2 C**  **2 O**  **4 • H**  **2 O. Heat until mixture coagulates,**  **then centrifuge and discard supernatant.**

**11.18 Add 10 mL water, 6 drops 1 N HNO 3**  **and 6 drops 5% (NH 4**  **) 2**  **C 2**  **O 4**  **• H 2**  **O. Heat**

**and stir in a hot-water bath a few minutes. Centri fuge and discard supernatant.** **SW-846 Update V 9320 - 7 Revision 1 July 2014**  **11.19 To determine yttrium yield, transfer quantit atively to a tared stainless steel**  **planchet with a minimum amount of water. Dry under an infrared lamp to a constant weight and**  **count in a low-background beta counter.**

**11.20 To the supernatant from step 7.15, add 4 mL 16 N HNO**  **3 and 2 mL (NH**  **4 )**  **2 SO**  **4 (200 mg/mL), stirring well after each addition. Ad**  **d 17.4 N acetic acid until barium sulfate precipitates. Then add 2 mL excess. Digest on a h**  **ot plate until precipitate settles. Centrifuge and discard supernatant.** 

**11.21 Add 20 mL basic EDTA reagent, rest in a hot- water bath, and stir until precipitate**  **dissolves. Add a few drops 10 N NaOH if precipitat e does not readily dissolve.** 

**11.22 Add 1 mL (NH 4**  **) 2**  **SO 4**  **(200 mg/mL) and stir thoroughly. Add 17.4 N aceti c acid**  **until barium sulfate precipitates. Then add 2 mL e xcess. Digest in a hot-water bath until**  **precipitate settles. Centrifuge and discard supern atant.** 

**11.23 Wash precipitate with 10 mL water. Centrifu ge and discard supernatant.** 

**11.24 Transfer precipitate to a tared stainless st eel planchet with a minimum amount of**  **water. Dry under an infrared lamp and weigh for ba rium yield determination.** 

**12.0 DATA ANALYSIS AND CALCULATIONS**

**12.1 Results need to be reported in units commensu rate with their intended use and** 

**all dilutions need to be taken into account when co mputing final results.** 

**12.2 Calculate the radium-228 concentration, D, in picocuries per liter as follows:** 

D	 C

2.22		EVR   1 −      1

1 −      1

   

**NOTE :**   

    **is a factor to correct the average count rate to t he count rate at** 

**the beginning of counting time.**

**where:**

**C = Average net count rate, cpm;**

**E = Counter efficiency, for actinium-228, or compar able beta energy**  **nuclide;**

**V = Liters of sample used;**

**R = Fractional chemical yield of yttrium carrier (S tep 11.18) multiplied**  **by fractional chemical yield of barrier carrier (St ep 11.23);** 

**2.22 = Conversion factor from disintegrations/minut e to picocuries;** 

**λ = The decay constant for actinium-228 (0.001884 m in**  **-1 );** **SW-846 Update V 9320 - 8 Revision 1 July 2014**  **t 1**  **= The time interval (in min) between the first ytt rium hydroxide**  **precipitation in Step 11.14 and the start of the co unting time;** 

**t 2**  **= The time interval of counting in min; and**

**t 3**  **= The ingrowth time of actinium-228 in min measure d from the last**  **barium sulfate precipitation in Step 11.10 to the f irst yttrium**  **hydroxide precipitation in Step 11.14.**

**13.0 METHOD PERFORMANCE**

**Performance data and related information are provi ded in SW-846 methods only as**  **examples and guidance. The data do not represent r equired performance criteria for users of**  **the methods. Instead, performance criteria should be developed on a project-specific basis,**  **and the laboratory should establish in-house QC per formance criteria for the application of this** 

**method. Performance data must not be used as absol ute QC acceptance criteria for laboratory** 

**QC or accreditation.**

**Performance data examples and guidance for this met hod currently are not currently available.** 

**14.0 POLLUTION PREVENTION**

**14.1 Pollution prevention encompasses any techniqu e that reduces or eliminates the**  **quantity and/or toxicity of waste at the point of g eneration. Numerous opportunities for pollution**  **prevention exist in laboratory operations. The EPA has established a preferred hierarchy of**  **environmental management techniques that places pol lution prevention as the management**  **option of first choice. Whenever feasible, laborat ory personnel should use pollution prevention**  **techniques to address their waste generation. When wastes cannot be feasibly reduced at the**  **source, the Agency recommends recycling as the next best option.** 

**14.2 For information about pollution prevention th at may be applicable to laboratories** 

**and research institutions consult** Less is Better: Laboratory Chemical Management for Waste

Reduction **, a free publication available from the American Ch emical Society (ACS), Committee**  **on Chemical Safety, http://portal.acs.org/portal/fileFetch/C/WPCP_01229**  **0/pdf/WPCP_012290.pdf.**

**15.0 WASTE MANAGEMENT**

**The EPA requires that laboratory waste management practices be conducted consistent**  **with all applicable rules and regulations. Laborat ories are urged to protect air, water, and land**  **by minimizing and controlling all releases from hoo ds and bench operations, complying with the**  **letter and spirit of any sewer discharge permits an d regulations, and by complying with all solid**  **and hazardous waste regulations, particularly the h azardous waste identification rules and land**  **disposal restrictions. For further information on waste management, consult**  The Waste Management Manual for Laboratory Personnel **available from the ACS at the address listed in**

**Sec. 14.2. SW-846 Update V 9320 - 9 Revision 1**  **July 2014 16.0 REFERENCES** 

**1. A.E. Greenberg, J.J. Connors, and D.J. Jenkens, eds., Standard Methods for the**  **Examination of Water and Wastewater, 15 th**  **ed., American Public Health Assoc., Washington, D.C., Method 707, p. 600, 1980.** 

**2. J.O. Johnson, Determination of Radium 228 in Nat ural Waters. Radiochemical Analysis**  **of Water. U.S. Geol. Surv., Water Supply Paper 169 6-G. U.S. Govt. Printing Office,**  **Washington, D.C., 1971.**

**3. H.L. Krieger, Prescribed Procedures for Measurem ent of Radioactivity in Drinking Water,**  **Environmental Monitoring and Support Laboratory, U. S. EPA, Cincinnati, OH, EPA**  **600/4-75-008, 1976.**

**17.0 TABLES, DIAGRAMS, FLOW CHARTS, AND VALIDATION DATA** 

**The following pages contain figures that provide i llustration for the procedures of this** 

**method. SW-846 Update V 9320 - 10 Revision 1**  **July 2014 METHOD 9320** 

**RADIUM-228 SW-846 Update V 9320 - 11 Revision 1**  **July 2014 METHOD 9320** 

**RADIUM-228 SW-846 Update V 9320 - 12 Revision 1**  **July 2014 METHOD 9320** 

**RADIUM-228 SW-846 Update V 9320 - 13 Revision 1**  **July 2014 Appendix A** 

**Summary of Revisions to Method 9320 (From Revision 0, September 1986)** 

**1. Improved overall method formatting for consisten cy with new SW-846 methods style**  **guidance. 2. Extensively reformatted “REAGENTS AND STANDARDS”**  **section and to meet current SW-846 method guidelines.**  **3. Updated and expanded “QUALITY CONTROL” section f or better adherence to current**  **SW-846 method guidelines and for improved alignment with current universal practices for**  **published analytical methods. 4. In Section 9.2, the recommendation of an initial**  **demonstration of proficiency for analysts and instrumentation and/or procedure changes was ad**  **ded. 5. The Section 11.7 was added; instructing a reagen**  **t water wash after the two HNO 3**  **washes in Sec. 11.6. This step will help prevent and redu**  **ce interferences later in the procedures and analysis.**  **6. The revision number was changed to one and the d ate published to July 2014.**