ASTM D512-2004 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

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1、Designation: D 512 04Standard Test Methods forChloride Ion In Water1This standard is issued under the fixed designation D 512; 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 indic

2、ates the year of last reapproval. Asuperscript epsilon (e) 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

3、(Test 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 PracticeD 2777

4、 77, and only Test Method B conforms also toPractice D 2777 86. Refer to Sections 14, 21, and 29 forfurther information.1.3 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-pr

5、iate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For a specifichazard statement, see 26.1.1.1.4 A former colorimetric test method was discontinued.Refer to Appendix X1 for historical information.2. Referenced Documents2.1 ASTM Standards:2D 106

6、6 Practice for Sampling SteamD 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 4127 Terminology Used with Ion-Select

7、ive ElectrodesD 5810 Guide for Spiking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE 200 Practice for Preparation, Standardization, and Stor-age of Standard and Reagent Solutions for ChemicalAnalysis3. Terminology3.1 Defin

8、itionsFor definitions of terms used in these testmethods, refer to Terminologies D 1129 and D 4127.4. Significance and Use4.1 Chloride ion is under regulation in water, and must,therefore, be measured accurately. It is highly detrimental tohigh-pressure boiler systems and to stainless steel, so moni

9、tor-ing is essential for prevention of damage. Chloride analysis iswidely used as a tool for estimating the cycles of concentration,such as in cooling tower applications. Processing waters andpickling solutions used in the food processing industries alsorequire dependable methods of analysis for chl

10、oride.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 the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.3Other gra

11、des 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 Water Unless otherwise indicated, refer-ences to water shall be understood to mean Type I reagentwater conforming to Sp

12、ecification D 1193. Other reagent watertypes may be used provided it is first ascertained that the wateris of sufficiently high purity to permit its use without adversely1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19

13、.05 on InorganicConstituents in Water.Current edition approved July 1, 2004. Published July 2004. Originally approvedin 1938. Last previous edition approved in 1989 as D 512 89 (1999).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm

14、.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 suggestions on the testing of reagents notlisted by the American Chem

15、ical 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 section appears at the end of this standard.Copyright ASTM Internation

16、al, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.affecting the precision and bias of the test method. Type IIwater was specified at the time of round robin testing of thistest method.6. Sampling6.1 Collect the sample in accordance with Practice D 1066and Practi

17、ces D 3370, as applicable.TEST METHOD AMERCURIMETRICTITRATION47. Scope7.1 This test method can be used to determine chloride ionin water, provided interferences are absent (see Section 9).7.2 Though not specified in the research report, the preci-sion statement is presumed to have been obtained usin

18、g 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 the concentrationrange 8.0 to 250 mg/L Cl.8. Summary of Test Method8.1 Dilute mercuric nitrate solution is added to an acidifiedsampl

19、e in the presence of mixed diphenylcarbazone-bromophenol blue indicator.The end point of the titration is theformation of the blue-violet mercury diphenylcarbazone com-plex.9. Interferences9.1 The anions and cations generally found in water offer nointerference. Zinc, lead, nickel, and ferrous and c

20、hromous 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 50 mg/L. Titration in thepresence of chromate ion requires indicator with extra back-ground color (alphazurine) and prior reduction

21、 for concentra-tions above 100 mg/L. Ferric ion above 10 mg/L must bereduced before titration, and sulfite ion must be oxidized.Bromide and fluoride will be partially titrated with the chlo-ride. Quaternary ammonium salts also interfere if present insignificant amounts (1 to 2 mg/L). Deep color may

22、alsointerfere.10. Apparatus10.1 Microburet, 1 or 5-mL, with 0.01-mL graduationintervals.11. Reagents and Materials11.1 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 (0.025N)Dis

23、solve 4.2830 g of mercuric nitrate (Hg(NO3)2H2O) in 50mL of water acidified with 0.5 mL of concentrated nitric acid(HNO3, sp gr 1.42). Dilute the acidified Hg(NO3)2solutionwith water to 1 L. Filter if necessary, and standardize againstthe standard sodium chloride (NaCl) solution, using the pro-cedur

24、e described in Section 12 (see Note 1).NOTE 1Sharpness 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 Indic

25、ator Solution5Dissolve 0.5 g of crystal-line diphenylcarbazone and 0.05 g of bromophenol bluepowder in 75 mLof ethyl alcohol (95 %), and dilute to 100 mLwith the alcohol (Note 2). Store in a brown bottle and discardafter 6 months (Note 3).NOTE 2Methanol, isopropanol, or ethanol denatured with either

26、methanol or isopropanol (Formula 3A) may be used if pure ethyl alcoholis not available. Other denatured ethanol formulae are not suitable.NOTE 3Liquid indicator generally deteriorates to the point that ityields no end-point color after 12 to 18 months of storage. Hightemperature (above 37.8C (100F)

27、and exposure to bright light mayshorten 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 (

28、HNO3, sp gr 1.42) with 997 volumes ofwater.11.6 pH Indicating Paper, long-range type, covering a pHrange 1 to 11.11.7 Sodium Chloride Solution, Standard (0.025N)Dryseveral grams of sodium chloride (NaCl) for1hat600C.Dissolve 1.4613 g of the dry salt in water, and dilute to 1 L at25C in a volumetric

29、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 approximately 50-mL volume if necessary. Determinean

30、 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 the color changes toyellow. Add 1 mL of excess

31、 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 excess of acid (Note4).NOTE 4The prescribed acidific

32、ation provides a satisfactory pH rangefrom 3.0 to 3.5. Acidified samples on which electrometric pH measure-ments have been made shall not be used for chloride determinations,because the use of the calomel reference electrode may introduce error dueto chloride contamination. For precise pH adjustment

33、 of samples having alow-chloride concentration, instrumental measurements may be made onone sample aliquot to determine treatment needed for another to be usedfor the chloride test.4For information of interest in connection with this test method, and supportingdata, refer to Clark, F. E., “Determina

34、tion of Chloride in Water,” AnalyticalChemistry, Vol 22, April 1950, pp. 553555, and Vol 22, November 1950, p. 1458.5This diphenylcarbazone 1-bromophenol blue indicator is covered by U.S.Patent No. 2,784,064.D51204212.3 Titrate the solution and a blank with 0.025 N Hg(NO3)2solution until a blue-viol

35、et color, as viewed by transmittedlight, persists throughout the solution (Note 5). Record themillilitres of Hg(NO3)2solution added in each case.NOTE 5The use of indicator modifications and the presence of heavymetal ions can change solution colors without affecting accuracy of thedetermination. For

36、 example, solutions containing alphazurine may bebright blue when neutral, grayish purple when basic, blue-green whenacidic, and blue-violet at the chloride end point. Solutions containingabout 100 mg/L nickel ion and normal mixed indicator are purple whenneutral, green when acid, and gray at the ch

37、loride end point. Whenapplying this test method to samples that contain colored ions or thatrequire modified indicator, it is recommended that the operator be familiarwith the specific color changes involved by experimenting with solutionsprepared as standards for comparison of color effects.12.4 If

38、 chromate ion is present in the absence of iron and inconcentration less than 100 mg/L, use the alphazurine modifiedmixed indicator (Note 1) and acidify the sample as described 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

39、 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 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

40、 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 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 a

41、nd 12.3.13. Calculation13.1 Calculate the chloride ion concentration, in milligramsper litre, in the original sample as follows:Chloride, mg/L 5 V12 V2! 3 N 3 35 453/Swhere:V1= standard Hg(NO3)2solution required for titration ofthe sample, mL,V2= standard Hg(NO3)2solution required for titration ofth

42、e blank, mL,N = normality of the Hg(NO3)2solution, andS = sample used in 12.1, mL.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

43、= concentration of 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

44、 14.2 is derivedfrom 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 PracticeD 2777, none was rejected, nor were any da

45、ta points deter-mined to be “outliers.” Three sample levels were run on at leastthree days. The method of “least squares” was used todetermine the precision statement, with correlation of 0.7394for SOand 0.9993 for ST.14.4 It is the responsibility of the analyst to assure thevalidity of this test me

46、thod for untested matrices.14.5 Precision and bias for this test method conforms toPractice D 2777 77, which was in place at the time ofcollaborative testing. Under the allowances made in 1.5 ofPractice D 2777 86, these precision and bias data do meetexisting requirements for interlaboratory studies

47、 of CommitteeD19 test methods.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

48、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 validated for the concentrationrange

49、8.0 to 250 mg/L Cl.16. Summary of Test Method16.1 Water adjusted to approximately pH 8.3 is titrated withsilver nitrate solution in the presence of potassium chromateindicator. The end point is indicated by persistence of thebrick-red silver chromate color.17. Interferences17.1 Bromide, iodide, and sulfide are titrated along with thechloride. Orthophosphate and polyphosphate interfere ifpresent in concentrations greater than 250 and 25 mg/L,respectively. Sulfite and objectionable color or turbidity mustbe eliminated. Compounds which precipitat