ASTM D512-2012 Standard Test Methods for Chloride Ion In Water《测定水中氯离子含量的标准试验方法》.pdf

1、Designation: D512 12Standard Test Methods forChloride Ion In Water1This standard is issued under the fixed designation D512; 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 indicat

2、es the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 These test methods cover the determination of chlorideion in water, wastewater (Te

3、st Method C only), and brines. Thefollowing three test methods are included:SectionsTest Method A (Mercurimetric Titration) 7 to14Test Method B (Silver Nitrate Titration) 15 to 21Test Method C (Ion-Selective Electrode Method) 22 to 291.2 Test MethodsA, B, and C were validated under PracticeD2777 77,

4、 and only Test Method B conforms also to PracticeD2777 86. Refer to Sections 14, 21, and 29 for furtherinformation.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafet

5、y 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 determine the applica-bility of regulatory limitations prior to use. For a specifichazard statement, see 26.1.1.1.5 A former colorimetric test m

6、ethod was discontinued.Refer to Appendix X1 for historical information.2. Referenced Documents2.1 ASTM Standards:2D1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods

7、of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD4127 Terminology Used with Ion-Selective ElectrodesD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE200 Practice for Prepa

8、ration, Standardization, and Storageof Standard and Reagent Solutions for Chemical Analysis3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, refer to Terminologies D1129 and D4127.4. Significance and Use4.1 Chloride ion is under regulation in waste water, andmust, ther

9、efore, be measured accurately. It is highly detrimen-tal to high-pressure boiler systems and to stainless steel, somonitoring is essential for prevention of damage. Chlorideanalysis is widely used as a tool for estimating the cycles ofconcentration, such as in cooling tower applications. Process-ing

10、 waters and pickling solutions used in the food processingindustries also require dependable methods of analysis forchloride.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of

11、the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.3Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.5.2 Purity of

12、Water Unless otherwise indicated, refer-ences to water shall be understood to mean Type I reagentwater conforming to Specification D1193. Other reagent watertypes may be used provided it is first ascertained that the water1These test methods are under the jurisdiction of ASTM Committee D19 onWater a

13、nd are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved June 15, 2012. Published July 2012. Originallyapproved in 1938. Last previous edition approved in 2010 as D512 10. DOI:10.1520/D0512-12.2For referenced ASTM standards, visit the ASTM we

14、bsite, www.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.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For su

15、ggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.1*A Summary of Changes sec

16、tion appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.is of sufficiently high purity to permit its use without adverselyaffecting the precision and bias of the test method. Type IIwater was specified

17、 at the time of round robin testing of thistest method.6. Sampling6.1 Collect the sample in accordance with Practice D1066and Practices D3370, as applicable.TEST METHOD AMERCURIMETRICTITRATION47. Scope7.1 This test method can be used to determine chloride ionin water, provided interferences are abse

18、nt (see Section 9).7.2 Though not specified in the research report, the preci-sion statement is presumed to have been obtained using Type IIreagent water. It is the responsibility of the analyst to assure thevalidity of this test method for untested matrices.7.3 This test method was validated for th

19、e concentrationrange 8.0 to 250 mg/L Cl.8. Summary of Test Method8.1 Dilute mercuric nitrate solution is added to an acidifiedsample in the presence of mixed diphenylcarbazone-bromophenol blue indicator.The end point of the titration is theformation of the blue-violet mercury diphenylcarbazone com-p

20、lex.9. Interferences9.1 The anions and cations generally found in water offer nointerference. Zinc, lead, nickel, and ferrous and chromous ionsaffect solution and end-point colors, but do not reduce theaccuracy of the titration when present in concentrations up to100 mg/L. Copper is tolerable up to

21、50 mg/L. Titration in thepresence of chromate ion requires indicator with extra back-ground color (alphazurine) and prior reduction for concentra-tions above 100 mg/L. Ferric ion above 10 mg/L must bereduced before titration, and sulfite ion must be oxidized.Bromide, iodide, and fluoride will be tit

22、rated or partiallytitrated with the chloride. Quaternary ammonium salts alsointerfere if present in significant amounts (1 to 2 mg/L). Deepcolor may also interfere.10. Apparatus10.1 Microburet, 1 or 5-mL, with 0.01-mL graduationintervals.11. Reagents and MaterialsNOTE 1Consult the manufacturer Mater

23、ial Safety Data Sheet for safework practices before working with reagents.11.1 Hydrogen Peroxide (30 % H2O2).11.2 Hydroquinone Solution (10 g/L)Dissolve1gofpurified hydroquinone in water and dilute to 100 mL.11.3 Mercuric Nitrate Solution, Standard (0.0125M;0.025N)Dissolve 4.2830 g of mercuric nitra

24、te(Hg(NO3)2H2O) in 50 mL of water acidified with 0.5 mL ofconcentrated nitric acid (HNO3, sp gr 1.42). Dilute the acidi-fied Hg(NO3)2solution with water to 1 L. Filter if necessary,and standardize against the standard sodium chloride (NaCl)solution, using the procedure described in Section 12 (see N

25、ote2).NOTE 2Sharpness of End PointThe end point, while sharp, can beimproved somewhat for certain types of water by adding several drops ofa 0.05-g/L solution of xylene cyanole FF or alphazurine blue-green dye(color index 714) to the titration sample.11.4 Mixed Indicator Solution5Dissolve 0.5 g of c

26、rystal-line diphenylcarbazone and 0.05 g of bromophenol bluepowder in 75 mLof ethyl alcohol (95 %), and dilute to 100 mLwith the alcohol (Note 3). Store in a brown bottle and discardafter 6 months (Note 4).NOTE 3Methanol, isopropanol, or ethanol denatured with eithermethanol or isopropanol (Formula

27、3A) may be used if pure ethyl alcoholis not available. Other denatured ethanol formulae are not suitable.NOTE 4Liquid indicator generally deteriorates to the point that ityields no end-point color after 12 to 18 months of storage. Hightemperature (above 37.8C (100F) and exposure to bright light mays

28、horten storage life.Adry powder mixture of the two indicator ingredientsis stable for much longer periods. Both the powder mixture (capsule form)and the liquid indicator are available commercially.11.5 Nitric Acid (3 + 997)Mix 3 volumes of concen-trated nitric acid (HNO3, sp gr 1.42) with 997 volume

29、s ofwater.11.6 pH Indicating Paper, long-range type, covering a pHrange 1 to 11.11.7 Sodium Chloride Solution, Standard (0.025N)Purchase a commercially available standard or prepare asfollows: Dry several grams of reagent grade sodium chloride(NaCl) for2hat110C. Dissolve 1.4613 g of the dry salt inw

30、ater, and dilute to 1 L at 25C in a volumetric flask.11.8 Sodium Hydroxide Solution (10 g/L)Dissolve 10 g ofsodium hydroxide (NaOH) in water and dilute to 1 L.12. Procedure12.1 Use a volume of sample such that it will contain notmore than 20 mg of chloride ion, diluting the sample withwater to appro

31、ximately 50-mL volume if necessary. Determinean indicator blank on 50 mL of chloride-free water, applyingthe same procedure followed for the sample.12.2 Add 5 to 10 drops of mixed indicator solution, andshake or swirl the flask. If a blue-violet or red color develops,add HNO3(3 + 997) dropwise until

32、 the color changes toyellow. Add 1 mL of excess acid. If a yellow or orange colorforms immediately on addition of the mixed indicator, addNaOH solution (10 g/L) dropwise until the color changes toblue-violet; then add HNO3(3 + 997) dropwise until the colorchanges to yellow and further add 1 mL exces

33、s of acid (Note5).NOTE 5The prescribed acidification provides a satisfactory pH range4For information of interest in connection with this test method, and supportingdata, refer to Clark, F. E., “Determination of Chloride in Water,” AnalyticalChemistry, Vol 22, April 1950, pp. 553555, and Vol 22, Nov

34、ember 1950, p. 1458.5This diphenylcarbazone 1-bromophenol blue indicator is covered by U.S.Patent No. 2,784,064.D512 122from 3.0 to 3.5. Acidified samples on which electrometric pH measure-ments have been made can be used for chloride determinations only if thepH electrode fill solution contains no

35、chloride, for example, use a pH halfcell and a double junction reference electrode with a sodium nitrate outerfill solution. Alternately, for precise pH adjustment of samples having alow-chloride concentration, instrumental measurements may be made onone sample aliquot to determine treatment needed

36、for another to be usedfor the chloride test.12.3 Titrate the solution and a blank with 0.025 N Hg(NO3)2solution until a blue-violet color, as viewed by transmittedlight, persists throughout the solution (Note 6). Record themillilitres of Hg(NO3)2solution added in each case.NOTE 6The use of indicator

37、 modifications and the presence of heavymetal ions can change solution colors without affecting accuracy of thedetermination. For example, solutions containing alphazurine may bebright blue when neutral, grayish purple when basic, blue-green whenacidic, and blue-violet at the chloride end point. Sol

38、utions containingabout 100 mg/L nickel ion and normal mixed indicator are purple whenneutral, green when acid, and gray at the chloride end point. Whenapplying this test method to samples that contain colored ions or thatrequire modified indicator, it is recommended that the operator be familiarwith

39、 the specific color changes involved by experimenting with solutionsprepared as standards for comparison of color effects.12.4 If chromate ion is present in the absence of iron and inconcentration less than 100 mg/L, use the alphazurine modifiedmixed indicator (Note 2) and acidify the sample as desc

40、ribed in12.2 but to pH 3 as indicated by pH indicating paper.Titrate thesolution as described in 12.3, but to an olive-purple end point.12.5 If chromate ion is present in the absence of iron and inconcentration greater than 100 mg/L, add 2 mL of freshhydroquinone solution and proceed as described in

41、 12.2 and12.3.12.6 If ferric ion is present in the absence or presence ofchromate ions, use a sample of such volume as to contain nomore than 2.5 mg of ferric ion or of ferric ion plus chromateion. Add 2 mL of fresh hydroquinone solution, and proceed asdescribed in 12.2 and 12.3.12.7 If sulfite ion

42、is present, add 0.5 mL of H2O2to 50 mLof the sample in the Erlenmeyer flask and mix for 1 min. Thenproceed as described in 12.2 and 12.3.13. Calculation13.1 Calculate the chloride ion concentration, in milligramsper litre, in the original sample as follows:Chloride, mg/L 5 VS2 Vb! 3 N 3 35 453/Swher

43、e:VS= standard Hg(NO3)2solution required for titrationof the sample, mL,Vb= standard Hg(NO3)2solution required for titrationof the blank, mL,N = normality of the Hg(NO3)2solution (see Note 7),S = sample used in 12.1, mL, and35 453 = 35.453 g/mole chloride * 1000 mg/g.NOTE 7The normality of the mercu

44、ric nitrate solution standard isbased on a 2:1 (Cl:Hg) reaction.14. Precision and Bias614.1 Precision StatementThe precision of this test methodmay be expressed as follows:ST5 0.023X 1 0.43SO5 0.002X 1 0.46where:ST= overall precision, mg/L,SO= single-operator precision, mg/L, andX = concentration of

45、 chloride ion determined.14.2 Bias Statement Recoveries of known amounts ofchloride were as follows:Amount Added,mg/LAmount Found,mg/L 6 % BiasStatisticallySignificant (95 %Confidence Level)250 248 0.80 no80.0 79.3 0.88 no8.00 7.51 6.13 yes14.3 The information presented in 14.1 and 14.2 is derivedfr

46、om round-robin testing in which five laboratories, includingseven operators, participated. Though not clearly specified inthe test report, the matrix is presumed to be Type II reagentwater. Of seven data sets ranked as described in PracticeD2777, none was rejected, nor were any data points determine

47、dto be “outliers.” Three sample levels were run on at least threedays. The method of “least squares” was used to determine theprecision statement, with correlation of 0.7394 for SOand0.9993 for ST.14.4 It is the responsibility of the analyst to assure thevalidity of this test method for untested mat

48、rices.14.5 Precision and bias for this test method conforms toPractice D2777 77, which was in place at the time ofcollaborative testing. Under the allowances made in 1.5 ofPractice D2777 08, these precision and bias data do meetexisting requirements for interlaboratory studies of CommitteeD19 test m

49、ethods.TEST METHOD BSILVER NITRATE TITRATION15. Scope15.1 This test method7is intended primarily for water wherethe chloride content is 5 mg/Lor more, and where interferencessuch as color or high concentrations of heavy metal ions renderTest Method A impracticable.15.2 Though not specified in the research report, the preci-sion and bias statement is presumed to have been obtainedusing Type II reagent water. It is the responsibility of theanalyst to assure the validity of this test method for untestedmatrices.15.3 This test method was valida