1、Designation: D 1179 04Standard Test Methods forFluoride Ion in Water1This standard is issued under the fixed designation D 1179; 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 ind
2、icates 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 methods2cover the determination of fluorideion in water. The follo
3、wing two test methods are given:SectionsTest Method ADistillation 7 to 13Test Method BIon Selective Electrode 14 to 221.2 Test Method A covers the accurate measurement of totalfluoride in water through isolation of the fluoride by distillationand subsequent measurement in the distillate by use of th
4、e ionselective electrode (ISE) method. The procedure covers therange from 0.1 to 2.6 mg/L of fluoride.1.3 Test Method B covers the accurate measurement ofsimple fluoride ion in water by means of an ion selectiveelectrode. With this test method, distillation is eliminatedbecause the electrode is not
5、affected by the interferencescommon to colorimetric procedures. Concentrations of fluoridefrom 0.1 to 1000 mg/L may be measured.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
6、appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For a specificprecautionary statement, see 12.1.2.1.5 Former Test Method A, SPADNS Photometric Proce-dure, was discontinued. Refer to Appendix X1 for historicalinformation.2. Referenced
7、Documents2.1 ASTM Standards:3D 1066 Practice for Sampling SteamD 1129 Terminology Relating to WaterD 1192 Guide for Equipment for Sampling Water andSteam in Closed Conduits4D 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee
8、 D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, refer to Terminology D 1129.4. Significance and
9、Use4.1 Simple and complex fluoride ions are found in naturalwaters. Fluoride forms complexing ions with silicon, alumi-num, and boron. These complexes may originate from the useof fluorine compounds by industry.4.2 Fluoridation of drinking water to prevent dental caries ispracticed by a large number
10、 of communities in this country.Fluoride is monitored to assure that an optimum treatment levelof 1.4 to 2.4 mg/L, depending on the corresponding range ofambient temperatures of 32 to 10C, is maintained.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indi
11、cated, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.5Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to pe
12、rmit its use without lessening the accuracy ofthe determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean Type I reagent waterconforming to Specification D 1193. Other reagent water typesmay be used provided it is first ascertained that the water i
13、s of1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved July 1, 2004. Published July 2004. Originally approvedin 1951. Last previous edition approved in 1999 a
14、s D 1179 9p.2Bellack, E., “Simplified Fluoride Distillation Method, Journal of the Ameri-can Water Works Association, Vol 50, 1958, p. 530.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
15、 information, refer to the standards Document Summary page onthe ASTM website.4Withdrawn.5Reagent 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
16、 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. (C) ASTM International. 100 Barr Harbour Dr. P.O.
17、 box C-700 West Conshohocken, Pennsylvania 19428-2959, United StatesCopyright by ASTM Intl (all rights reserved); Sun Dec 20 20:08:08 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.sufficiently high purity to permit its use without ad
18、verselyaffecting 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 1066,Specification D 1192, or Practice D 3370, as applicable.TEST METHOD ADISTILLATION7. Scope7
19、.1 This test method is applicable to the accurate determi-nation of fluoride ion in water, including most wastewaters.This test method may not be applicable to concentrated brinesand oily wastes.7.2 This test method was tested on reagent water andwastewater. It is the users responsibility to ensure
20、the validityof this test method for waters of untested matrices.8. Summary of Test Method8.1 The fluoride is distilled as hydrofluosilicic acid and isdetermined by the ion selective electrode.9. Interferences9.1 In sample distillation, interferences may be experienceddue to the following factors.9.1
21、.1 Aluminum in excess of 300 mg/L and silicon dioxideas colloidal silica in excess of 400 mg/L will hold up in thecondenser to a certain extent, causing low results and acting asa positive interference for subsequent samples of lower fluoridecontent. In these cases, the condenser should be flushed w
22、ith300 to 400 mL of water and the washwater added to thedistillate. The distillate may then be diluted to 1.0 L. If theanalyst prefers, a smaller sample aliquot diluted to 300 mLmaybe selected for distillation.9.1.2 Sea water, brines, and generally samples of dissolvedsolids in excess of 2500 mg/L w
23、ill cause bumping in thedistillation flask. Dilution of the sample with fluoride-freewater to a lesser-dissolved solids concentration is an effectiveremedy to bumping.9.1.3 Samples containing oily matter which may result in atwo-phase distillate, an emulsion, or anything other than a cleardistillate
24、 may prevent accurate measurement of fluoride. Suchsamples should be extracted initially with a suitable solvent(such as ether, chloroform, benzene, and similar solvents) toremove the oily material, and then warmed on a steam bath toremove traces of the added solvent.10. Apparatus10.1 Distillation A
25、ssemblyGlassware consisting of a 1-L,round bottom, borosilicate boiling flask, an adapter with athermometer opening, a connecting tube, a condenser, and athermometer reading to 200C, assembled as shown in Fig. 1.Standard-taper or spherical ground glass joints shall be usedthroughout the apparatus.11
26、. Reagents11.1 Silver Sulfate (Ag2SO4), powder.11.2 Sodium Arsenite Solution (2 g/L)Dissolve2gofsodium arsenite (NaAsO2) in water and dilute to 1 L.11.3 Sodium Fluoride Solution, Standard (1.0 mL = 0.01mg F)Dissolve 0.2210 g of sodium fluoride (NaF) in waterand dilute to 1.0 L. Dilute 100 mL of this
27、 solution to 1.0 L withwater. Store in borosilicate glass or polyethylene.11.4 Sulfuric Acid (H2SO4), Concentrated (sp gr 1:84).12. Procedure12.1 Distillation:12.1.1 Place 400 mL of water in the distilling flask and add200 mL of concentrated H2SO4(sp gr 1.84). Observe the usualprecautions while mixi
28、ng the H2SO4by slow addition of theacid accompanied by constant swirling. Add sufficient boilingstones6and assemble the apparatus as shown in Fig. 1. Heat thesolution in the flask, preferably with an electric heating mantle,until the temperature of the contents reaches exactly 180C. (Aquartz heating
29、 mantle is preferred in order to reach the required180C in a minimum time.) While heating, the tip of thethermometer must extend below the level of the liquid in theflask. Discard the distillate. The procedure, to this step, servesto adjust the acid-water ratio for subsequent distillations.12.1.2 Ca
30、utionCool the acid-water mixture to below100C, slowly add 300 mL of sample, and mix thoroughlybefore heating. Distill as described in 12.1.1, until the tempera-ture reaches 180C. Do not allow the temperature to exceed180C; excessive carryover of sulfate occurs at temperatures of6Glass beads must be
31、of a soft glass (rather than borosilicate). Use about 12beads. Soft beads will provide silica to the fluoride and protect the distillation flask.AHeating mantle (quartz).BRound-bottom flask, 1000 mL.CAdapter with thermometer opening.DThermometer, 200C.EConnecting tube.FGraham condenser, 300 mm.GVess
32、el, calibrated at 300 mL.FIG. 1 Distillation Assembly for Fluoride IsolationD1179042Copyright by ASTM Intl (all rights reserved); Sun Dec 20 20:08:08 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.or above 180C, resulting with interfe
33、rence in the subsequentfluoride measurement.12.1.3 Collect the distillate in any suitably calibrated vessel.If a calibrated vessel is used, it is possible to dispense withthermometer readings and stop the distillation when the vol-ume of distillate reaches 300 mL.12.1.4 In the case of samples contai
34、ning chlorides in con-centrations which may interfere in the subsequent reaction, addAg2SO4to the distillation mixture at a rate of 5 mg/mg ofchloride.12.1.5 The acid-water distilling solution may be used re-peatedly until the buildup of interference materials equals theconcentration given in Sectio
35、n 9.12.2 Analysis:12.2.1 Use Test Method B (Ion Selective Electrode) with thebuffer solution described in 18.1.13. Precision and Bias13.1 The precision and bias for Test Method A, shown inTable 1 and Table 2 were determined using distillation fol-lowed by an ion selective electrode finish. Four conc
36、entrationsand three replicates were provided by six laboratories forreagent water and wastewater.13.2 Precision and bias for this test method conform toPractice D 277777, which was in place at the time ofcollaborative testing. Under the allowances made in 1.4 of D277798, these precision and bias dat
37、a do meet existingrequirements for interlaboratory studies of Committee D19 testmethods.TEST METHOD BION SELECTIVE ELECTRODE14. Scope14.1 This test method is applicable to the measurement offluoride ion in finished waters, natural waters, and mostindustrial wastewaters. With this test method, distil
38、lation iseliminated and concentrations of fluoride from 0.1 to 1000mg/L may be measured.14.2 The test method is not applicable to samples containingmore than 10 000 mg/L of dissolved solids.14.3 This test method was tested on reagent water. It is theusers responsibility to ensure the validity of thi
39、s test methodfor waters of untested matricies.15. Summary of Test Method15.1 The fluoride is determined potentiometrically using anion selective fluoride electrode in conjunction with a standardsingle junction, sleeve-type reference electrode, and a pHmeter having an expanded millivolt scale, or an
40、ISE meterhaving a direct concentration scale for fluoride.15.2 The fluoride electrode consists of a lanthanum fluoridecrystal across which a potential is developed by fluorideions.7,8The cell may be represented by Ag/AgCl, Cl (0.3), F(0.001) LaF3/test solution/KCl/AgCl/Ag.16. Interferences16.1 Extre
41、mes of pH interfere; sample pH should be be-tween 5.0 and 9.0.16.2 Polyvalent cations of Si+4,Fe+3, andAl+3interfere byforming complexes with fluoride. The degree of interferencedepends upon the concentration of fluoride, and the pH of thesample (see Table 3). The addition of the buffer solution, 18
42、.1,buffers the solution pH and will complex small amounts ofaluminum, as well as silicon and iron. The use of one of thetwo selective buffers (see 18.2 and 18.3) is recommended whenaluminum is present, because they are more effective over agreater range of aluminum concentrations.16.3 Interferences
43、usually encountered in other test meth-ods, such as sulfate or phosphate, do not affect this test method.17. Apparatus17.1 pH Meter, with expanded millivolt scale or selective-ion meter.7Frant, M.S., and Ross, J.W., “Electrode for Sensing Fluoride Ion Activity inSolution,” Science, Vol 154, 1966, p.
44、 1553.8Frant, M.S., and Ross, J.W., “Use of a Total Ionic Strength Adjustment Bufferfor Electrode Determination of Fluoride in Water Supplies,” Anal. Chem., Vol 40,1968, p. 1169.TABLE 1 Determination of PrecisionFinal Statistics for TestMethod ANOTEPrecision of Test Method A was determined from roun
45、d robindata using distillation with ion selective electrode finish.Amount added, mg/L 0.150 0.560 0.840 2.600Reagent WaterConcentration, x 0.147 0.558 0.818A2.520St0.033 0.053 0.034A0.099So0.013 0.017 0.004A0.031WastewaterConcentration, xA0.126 0.505 0.771 2.454ASt0.048 0.068 0.092 0.070ASo0.018 0.0
46、13 0.017 0.030AACalculated with outlier point removed from data base.TABLE 2 Determination of Bias for Test Method ANOTEBias of Test Method A was determined from round robin datausing distillation with ion selective electrode finish.Amountaddedmg/LMean re-coverymg/LBias % BiasStatisticallysignifican
47、tat 5 % levelReagent Water0.150 0.147 0.003 2.0 % no0.560 0.558 0.002 0.4 % no0.840 0.818 0.022 2.6 % yes2.600 2.520 0.080 3.1 % yesWastewater0.150 0.126 0.024 16.0 % no0.560 0.505 0.055 9.8 % yes0.840 0.771 0.069 8.2 % yes2.600 2.454 0.146 5.7 % yesTABLE 3 Allowable Interference Levels with Selecti
48、ve IonElectrode and BufferAInterfering IonMaximum Allowable Concentration at1.0 mg/L FAl+30.5Si+450Fe+365ARefer to 16.2 for description of interfering cations.D1179043Copyright by ASTM Intl (all rights reserved); Sun Dec 20 20:08:08 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License A
49、greement. No further reproductions authorized.17.2 Fluoride Ion Selective Electrode.17.3 Reference Electrode, single-junction sleeve-type.17.4 Mixer, magnetic, with a TFE-fluorocarbon coated stir-ring bar.18. Reagents18.1 Buffer Solution (pH from 5.0 to 5.5)To approxi-mately 500 mL of water, add 57 mL of glacial acetic acid (spgr 1.06), 58 g of sodium chloride (NaCl), and 0.30 g of sodiumcitrate dihydrate in a 1000-mL beaker. Stir the solution todissolve, and cool to room temperature. Adjust the pH of thesolution to between
