ASTM D3920-2018 Standard Test Method for Strontium in Water《水中锶的标准试验方法》.pdf

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1、Designation: D3920 12D3920 18Standard Test Method forStrontium in Water1This standard is issued under the fixed designation D3920; 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 parentheses i

2、ndicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of dissolved and total recoverable strontium in water and wastewater by atomicabsorption spectroscopy.1.2 The test

3、method is applicable in the range from 0.1 to 1 mg/L of strontium. The range may be extended by dilution of theoriginal sample.1.3 Round-robin data were obtained in natural and reagent water matrices. It is the users responsibility to ensure the validityof the test method for waters of untested matr

4、ices.1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values statedgivenin each system parentheses are mathematical conversions and may not be exact equivalents; therefore, each system shall be usedindependently of the other.to inch-pound un

5、its that are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenviron

6、mental practices and determine theapplicability of regulatory limitations prior to use. Specific precautionary statements are given in 8.4 and 8.9.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on P

7、rinciples for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD1976 Test Method

8、for Elements in Water by Inductively-Coupled Argon Plasma Atomic Emission SpectroscopyD2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD4691 Practice for Measuring Elements in Water by Fl

9、ame Atomic Absorption SpectrophotometryD4841 Practice for Estimation of Holding Time for Water Samples Containing Organic and Inorganic ConstituentsD5673 Test Method for Elements in Water by Inductively Coupled PlasmaMass SpectrometryD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Wri

10、ting Quality Control Specifications for Standard Test Methods for Water Analysis3. Terminology3.1 DefinitionsDefinitions: For definitions of terms used in this test method, refer to Terminology D1129.3.1.1 For definitions of terms used in this standard, refer to Terminology D1129.3.2 Definitions of

11、Terms Specific to This Standard:3.2.1 total recoverable strontium, nan arbitrary analytical a descriptive term relating to the forms of strontium that aredeterminable by the digestion procedure described in this test method.3.2.2 laboratory control sample, na solution with a certified concentration

12、of the strontium.1 This test method is under the jurisdiction ofASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents in Water.Current edition approved Sept. 1, 2012Feb. 1, 2018. Published September 2012 May 2018. Originally approved in 1980. L

13、ast previous edition approved in 20072012 asD3920 02 (2007)D3920 12.1. DOI: 10.1520/D3920-12.10.1520/D3920-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the sta

14、ndards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurat

15、ely, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Dr

16、ive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Method4.1 Strontium is determined by atomic absorption spectrophotometry. The sample is aspirated into an air-acetylene flamefollowing the addition of lanthanum chloride/potassium chloride solution. Samples containi

17、ng particulate matter that may clog theaspirator capillary or burner, thus producing inaccurate results, are filtered through a 0.45-m membrane filter prior to testing.5. Significance and Use5.1 Although most potable supplies contain little strontium, some well waters in the midwestern part of the U

18、nited States havelevels as high as 39 mg/L.35.2 This test method affords a reliable means of accurately determining strontium and correcting calcium results obtained bythe methods cited in 6.2.5.3 ICP-MS or ICP-AES may also be appropriate but at a higher instrument cost. See Test Methods D1976 and D

19、5673.6. Interferences6.1 Chemical interference caused by silicon, aluminum, and phosphate is controlled by adding lanthanum chloride. Potassiumchloride is added to suppress the ionization of strontium.NOTE 1A nitrous oxide-acetylene flame has been used successfully by some to remove chemical interfe

20、rences.6.2 Strontium chemically resembles calcium and causes a positive error in gravimetric and titrimetric methods for calciumdetermination.7. Apparatus7.1 Atomic Absorption Spectrophotometer for use at 460.7 nm. A general guide for the use of flame atomic absorptionapplications is given in Practi

21、ce D4691.NOTE 2The manufacturers instructions should be followed for setting instrumental parameters.7.2 Strontium Hollow-Cathode Lamp.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall

22、conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available. 4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy

23、 of the determination.8.2 Purity of WaterUnless otherwise indicated, reference to water shall be understood to mean reagent water conforming toSpecification D1193, Type I, II, and III water. Type I is preferred and more commonly used. Other reagent water types may be usedprovided it is first ascerta

24、ined that the water is of sufficiently high purity to permit its use without adversely affecting the precisionand bias of the test method. Type II water was specified at the time of round robin testing of this test method.NOTE 3The user must ensure the type of reagent water chosen is sufficiently fr

25、ee of interferences.The water should be analyzed using the test method.8.3 Hydrochloric Acid (sp gr 1.19)Concentrated hydrochloric acid (HCl).8.4 Lanthanum Chloride/Potassium Chloride SolutionDissolve 11.73 g of lanthanum oxide (La2O3) in a minimum amount ofconcentrated hydrochloric acid (approximat

26、ely 50 mL.). Add 1.91 g of potassium chloride (KCl). Allow solution to cool to roomtemperature and dilute to 100 mL with water. (WarningAdd acid slowly and in small portion to control the reaction rate uponmixing.Warning)Add acid slowly and in small portion to control the reaction rate upon mixing.)

27、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 strontium nitrate (Sr(NO3)2) in a 1-L flask containing10 mL of concentrated HCl and 700 mL of water. Dilute to 1000 mL with water. A purchased strontium stock solution ofappropriate kn

28、own purity is also acceptable.8.7 Strontium Solution, Standard (1 mL = 0.010 mg Sr)Dilute 5.0 mL of strontium solution standard to 500 mL with water.8.8 OxidantAir that has been cleaned and dried through a suitable filter to remove oil, water, and other foreign substances,is the usual oxidant.3 Stan

29、dard Method for the Examination of Water and Wastewater, 14th Ed. American Public Health Assn., Washington, DC 20005.4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed bythe American Chemical

30、 Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D3920 1828.9 FuelStandard, commercially available acetylene is the usual fuel. Acetone, always p

31、resent in acetylene cylinders, can beprevented from entering the burner system by replacing the cylinder when the pressure reaches 490 kPa (70 psig).(WarningPurified grade acetylene containing a special proprietary solvent other than acetone should not be used with poly(vinyl chloride) tubing as wea

32、kening of the walls may result and cause a potentially hazardous situation.Warning)Purified gradeacetylene containing a special proprietary solvent other than acetone should not be used with poly (vinyl chloride) tubing asweakening of the walls may result and cause a potentially hazardous situation.

33、)8.10 Filter PaperPurchase suitable filter paper. Typically the filter papers have a pore size of 0.45-m membrane. Materialsuch as fine-textured, acid-washed, ashless paper, or glass fiber paper are acceptable. The user must first ascertain that the filterpaper is of sufficient purity to use without

34、 adversely affecting the bias and precision of the test method.9. Sampling9.1 Collect the samples in accordance with instructions in Practices D3370. The holding time for the samples may be calculatedin accordance with Practice D4841.9.2 To preserve the samples add concentrated HNO3 (sp gr 1.42) to

35、a pH of 2 or less immediately at the time of collection;normally about 2 mL/L is required. If only dissolved strontium is to be determined, filter (8.10) the samples at time of collectionthrough a 0.45-m membrane filter before acidification.NOTE 4Alternatively, the pH may be adjusted in the laborato

36、ry if the sample is returned within 14 days. within 14 days of collection. This couldreduce hazards of working with acids in the field when appropriate.10. Standardization10.1 An effective way to clean all glassware to be used for preparation of standard solutions or in the digestion step, or both,i

37、s by soaking the glassware for 2 h first with HNO3 (1 + 1) and then rinsing with reagent water.10.2 Prepare a blank and at least four working standards to bracket the expected strontium concentration range of the samplesto be analyzed by diluting the standard strontium solution (8.6) to the desired

38、concentrations. Select concentrations that will givea zero, middle, and maximum points for the analytical curve.10.3 Pipette 10.0 mL of each standard into a 50-mL beaker or flask and add 1.0 mL of lanthanum chloride/potassium chloridesolution. Mix well by swirling.10.4 To test the suitability of rea

39、gents used in the analysis, zero the instrument while aspirating reagent water.Aspirate the zerostandard and record the response. If the zero standard produces a response sufficient to affect the detection limit or accuracy, orboth, of the test method, the contaminated reagent should be identified a

40、nd replaced with a grade of suitable quality beforeproceeding.10.5 Aspirate the blank (zero standard) and adjust the instrument reading to zero. Aspirate standards and record the instrumentreading for each. Aspirate reagent water between each standard.NOTE 5Best results have been obtained with a sli

41、ghtly fuel rich flame.10.6 Construct Read directly in concentration if this capability is provided with the instrument or measure the absorbance ofthe standards or construct an analytical curve by plotting the absorbance of standards versus milligrams of strontium per litre.Alternatively, read direc

42、tly in concentration if this capability is provided in the instrument.11. Procedure11.1 For total recoverable strontium, add 5 mL of concentrated nitric acid (8.5)(8.5) to 100 mL of the sample in a 250-mLErlenmeyer flask, and mix well. Heat the sample at 95C (between 65C and 95C) on a steam bath/hot

43、 plate below boiling in awell-ventilated fume hood until the volume is reduced to 15 to 20 mL.mL, making certain that the samples do not boil.NOTE 6When testing samples of brine or samples containing a large amount of solids, the amount of reduction in volume is left to the discretionof the analyst.

44、NOTE 7Many laboratories have found block digestion systems a useful way to digest samples for trace metals analysis. Systems typically consist ofeither a metal or graphite block with wells to hold digestion tubes. The block temperature controller must be able to maintain uniformity of temperatureacr

45、oss all positions of the block. The digestion block must be capable of maintaining a temperature between 65C and 95C. For trace metals analysis,the digestion tubes should be constructed of polypropylene and have a volume accuracy of at least 0.5%. 0.5 %. All lots of tubes should come with acertifica

46、te of analysis to demonstrate suitability for their intended purpose. If a block digestion system is used, reduced volumes of samples and reagentswill be required. Make sure that the reagent volumes maintain the same proportions as in the macro method.11.2 If color in the digested solution indicates

47、 the presence of partially oxidized materials, add additional nitric acid andapproximately 90 mL of reagent water to the cooled solution and repeat the digestion as before. Repeat this step several times ifnecessary.11.3 Cool and filter the digested solution through a suitable filter (such as fine-t

48、extured, acid-washed ashless paper)paper; 8.10)into a 100-mL volumetric flask. Wash the filter paper 2 to 3 times and make up to volume with reagent water.Areagent blank (100D3920 183mLof reagent water and 5 mLof concentrated nitric acid) should be carried through the digestion process and treated a

49、s instructedin 10.310.4. An unacceptable high response could indicate that the nitric acid was of poor quality.NOTE 8If only dissolved strontium is to be determined, filter portion of 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 chloride/potassium chloride solution (8.4)(8.4) to each sample. Mix well by swirling.11.6 Aspirate each sample and record its absorbance or concentration. Aspirate reagent wate