1、Designation: D 3920 02 (Reapproved 2007)e1Standard Test Method forStrontium in Water1This standard is issued under the fixed designation D 3920; 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
2、 parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEEditorial changes were made throughout in September 2007.1. Scope1.1 This test method covers the determination of dissolvedand total recoverable stro
3、ntium in water and wastewater byatomic absorption spectroscopy.1.2 The test method is applicable in the range from 0.1 to 1mg/L of strontium. The range may be extended by dilution ofthe original sample.1.3 Round-robin data were obtained in natural and reagentwater matrices. It is the users responsib
4、ility to ensure thevalidity of the test method for waters of untested matrices.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and dete
5、rmine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in 8.4 and 8.9.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias of
6、Applicable Test Methods of Committee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 4691 Practice for Measuring Elements in Water by FlameAtomic Absorption SpectrophotometryD 4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic Constit
7、uentsD 5810 Guide for Spiking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology D 1129.3.2 Definitions of Terms Specific to This Standard:3
8、.2.1 total recoverable strontium, nan arbitrary analyticalterm relating to the forms of strontium that are determinable bythe digestion procedure described in this test method.3.2.2 laboratory control sample, na solution with a cer-tified concentration of the strontium.4. Summary of Test Method4.1 S
9、trontium is determined by atomic absorption spectro-photometry. The sample is aspirated into an air-acetylene flamefollowing the addition of lanthanum chloride/potassium chlo-ride solution. Samples containing particulate matter that mayclog the aspirator capillary or burner, thus producing inaccurat
10、eresults, are filtered through a 0.45-m membrane filter prior totesting.5. Significance and Use5.1 Although most potable supplies contain little strontium,some well waters in the midwestern part of the United Stateshave levels as high as 39 mg/L.35.2 This test method affords a reliable means of accu
11、ratelydetermining strontium and correcting calcium results obtainedby the methods cited in 6.2.6. Interferences6.1 Chemical interference caused by silicon, aluminum, andphosphate is controlled by adding lanthanum chloride. Potas-sium chloride is added to suppress the ionization of strontium.NOTE 1A
12、nitrous oxide-acetylene flame has been used successfullyby some to remove chemical interferences.6.2 Strontium chemically resembles calcium and causes apositive error in gravimetric and titrimetric methods for cal-cium determination.1This test method is under the jurisdiction of ASTM Committee D19 o
13、n Waterand is the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved Aug. 1, 2007. Published September 2007. Originallyapproved in 1980. Last previous edition approved in 2002 as D 3920 02.2For referenced ASTM standards, visit the ASTM website, ww
14、w.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Standard Method for the Examination of Water and Wastewater, 14th Ed.American Public Health Assn., Washington, DC 2000
15、5.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Apparatus7.1 Atomic Absorption Spectrophotometer for use at 460.7nm. A general guide for the use of flame atomic absorptionapplications is given in Practice D 4691.NOTE 2The manufa
16、cturers instructions should be followed for set-ting instrumental parameters.7.2 Strontium Hollow-Cathode Lamp.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specificat
17、ions of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Pu
18、rity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Specification D 1193, Type I, II, and III water. Type I ispreferred and more commonly used. Other reagent water typesmay be used provided it is first ascertained that the water is ofsuff
19、iciently high purity to permit its use without adverselyaffecting the precision and bias of the test method. Type IIwater was specified at the time of round robin testing of thistest method.NOTE 3The user must ensure the type of reagent water chosen issufficiently free of interferences. The water sh
20、ould be analyzed using thetest method.8.3 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).8.4 Lanthanum Chloride/Potassium Chloride SolutionDissolve 11.73 g of lanthanum oxide (La2O3) in a minimumamount of concentrated hydrochloric acid (approximately 50mL.). Add 1.91 g of potass
21、ium chloride (KCl). Allow solutionto cool to room temperature and dilute to 100 mL with water.(WarningAdd acid slowly and in small portion to controlthe reaction rate upon mixing.)8.5 Nitric Acid (sp gr 1.42)Concentrated HNO3.8.6 Strontium Solution, Stock (1.0 mL = 1.0 mg Sr)Dissolve 2.415 g of stro
22、ntium nitrate (Sr(NO3)2) in a 1-L flaskcontaining 10 mL of concentrated HCl and 700 mL of water.Dilute to 1000 mL with water.8.7 Strontium Solution, Standard (1 mL = 0.010 mg Sr)Dilute 5.0 mL of strontium solution standard to 500 mL withwater.8.8 OxidantAir that has been cleaned and dried through as
23、uitable filter to remove oil, water, and other foreign sub-stances, is the usual oxidant.8.9 FuelStandard, commercially available acetylene isthe usual fuel. Acetone, always present in acetylene cylinders,can be prevented from entering the burner system by replacingthe cylinder when the pressure rea
24、ches 490 kPa (70 psig).(WarningPurified grade acetylene containing a special pro-prietary solvent other than acetone should not be used withpoly (vinyl chloride) tubing as weakening of the walls mayresult and cause a potentially hazardous situation.)9. Sampling9.1 Collect the samples in accordance w
25、ith instructions inPractices D 3370. The holding time for the samples may becalculated in accordance with Practice D 4841.9.2 To preserve the samples add concentrated HNO3(sp gr1.42) to a pH of 2 or less immediately at the time of collection;normally about 2 mL/L is required. If only dissolved stron
26、tiumis to be determined, filter the samples at time of collectionthrough a 0.45-m membrane filter before acidification.10. Standardization10.1 Prepare a blank and at least four working standards tobracket the expected strontium concentration range of thesamples to be analyzed by diluting the standar
27、d strontiumsolution (8.6) to the desired concentrations. Select concentra-tions that will give a zero, middle, and maximum points for theanalytical curve.10.2 Pipette 10.0 mL of each standard into a 50-mL beakeror flask and add 1.0 mL of lanthanum chloride/potassiumchloride solution. Mix well by swi
28、rling.10.3 To test the suitability of reagents used in the analysis,zero the instrument while aspirating reagent water.Aspirate thezero standard and record the response. If the zero standardproduces a response sufficient to affect the detection limit oraccuracy, or both, of the test method, the cont
29、aminated reagentshould be identified and replaced with a grade of suitablequality before proceeding.10.4 Aspirate the blank (zero standard) and adjust theinstrument reading to zero. Aspirate standards and record theinstrument reading for each. Aspirate reagent water betweeneach standard.NOTE 4Best r
30、esults have been obtained with a slightly fuel rich flame.10.5 Construct an analytical curve by plotting the absor-bance of standards versus milligrams of strontium per litre.Alternatively, read directly in concentration if this capability isprovided in the instrument.11. Procedure11.1 For total rec
31、overable strontium, add 5 mL of concen-trated nitric acid to 100 mL of the sample in a 250-mLErlenmeyer flask, and mix well. Heat the sample at 95C on asteam bath/hot plate in a well-ventilated fume hood until thevolume is reduced to 15 to 20 mL.NOTE 5When testing samples of brine or samples contain
32、ing a largeamount of solids, the amount of reduction in volume is left to thediscretion of the analyst.11.2 If color in the digested solution indicates the presenceof partially oxidized materials, add additional nitric acid andapproximately 90 mL of reagent water to the cooled solutionand repeat the
33、 digestion as before. Repeat this step severaltimes if necessary.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals
34、, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D 3920 02 (2007)e1211.3 Cool and filter the digested solution through a suitablefilter (such as fine-textured, acid-washed ashless paper) into a100-mL v
35、olumetric flask. Wash the filter paper 2 to 3 times andmake up to volume with reagent water. A reagent blank (100mL of reagent water and 5 mL of concentrated nitric acid)should be carried through the digestion process and treated asinstructed in 10.3. An unacceptable high response couldindicate that
36、 the nitric acid was of poor quality.NOTE 6If only dissolved strontium is to be determined, filter portionof the sample through a 0.45-m membrane filter and proceed with 11.4.11.4 Pipette 10.0 mL of sample, or a dilution of the sample,into a 50-mL beaker or flask.11.5 Add 1.0 mL of lanthanum chlorid
37、e/potassium chloridesolution to each sample. Mix well by swirling.11.6 Aspirate each sample and record its absorbance orconcentration. Aspirate reagent water between each sample.11.7 For instruments that do not readout directly in concen-tration, determine the strontium concentration of the aspirate
38、dsolution from the analytical curve (10.5).12. Calculation12.1 Where dilutions have been made, calculate the concen-tration of strontium in the original sample as follows:Sr, mg/L 5 A 3BCwhere:A = Sr read from the analytical curve (10.5), mg/L,B = total final volume of the diluted sample, andC = vol
39、ume of original sample diluted.13. Precision and Bias513.1 The overall precision (reagent and waters of choice)and the single-operator precision for reagent water, based ondata from eight participating laboratories involving twelveoperators, varies with the quantity measured within the desig-nated r
40、ange of the test method as shown in Fig. 1.13.2 The single-operator precision for waters of choice canbe defined by the expression 0.023 # So# 0.026, with themean precision value of 0.024 mg/L over the designated range.13.3 Recoveries of known amounts of strontium in a seriesof prepared standards we
41、re as given in Table 1.13.4 This test method was evaluated with reagent andnatural water matrices. These data may not apply to waters ofother matrices.13.5 Precision and bias for this test method conforms toPractice D 2777 77, which was in place at the time ofcollaborative testing. Under the allowan
42、ces made in 1.4 ofD 2777 06, these precision and bias data do meet existingrequirements for interlaboratory studies of Committee D19 testmethods.NOTE 7The nitric acid digestion steps were not performed in theround-robin of this test method. It is an approved, recommended practicefor determining tota
43、l recoverable metals by atomic absorption spectrom-etry; however, its use can be expected to increase the variability of finalresults. The user should verify its suitability for a matrix of interest byevaluating recovery for spikes that have been taken through the digestionprocess (Guide D 5810).14.
44、 Quality Control (QC)14.1 The following quality control information is recom-mended for the determination of strontium in water.14.2 For each method the instrument shall be calibratedusing a minimum of four calibration standards and a calibrationblank. The calibration correlation coefficient shall b
45、e equal toor greater than 0.990. In addition to the initial calibrationblank, a calibration blank should be analyzed at the end of thebatch run to ensure contamination was not a problem duringthe batch analysis.14.3 An instrument check standard shall be analyzed at aminimum frequency of 10 % through
46、out the batch analysis.The value of the instrument check standard should fall between80 % and 120 % of the true value.14.4 Two method blanks shall be prepared ensuring that anadequate method blank volume is present for a minimum ofseven repetitive analysis. The standard deviation of the methodblank
47、is used to determine the minimum detectable concentra-tion of each sample and control in the batch.14.5 A Laboratory Control Sample shall be analyzed witheach batch of sample at a minimum frequency of 10 %.14.6 If the QC for the sample batch is not within theestablished control limits, reanalyze the
48、 samples or qualify theresults with the appropriate flags, or both.14.7 Blind control samples should be submitted by anoutside agency in order to determine the laboratory perfor-mance capabilities.15. Keywords15.1 atomic absorption; strontium; water5Supporting data have been filed at ASTM Internatio
49、nal Headquarters and maybe obtained by requesting Research Report RR:D19-1054.D 3920 02 (2007)e13FIG. 1 Interlaboratory Precision for Strontium in WaterD 3920 02 (2007)e14ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time
