1、Designation: D1179 16Standard Test Methods forFluoride Ion in Water1This standard is issued under the fixed designation D1179; 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 () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 These test methods2cover the determination of fluorideion in water. The fol
3、lowing two test methods are given:SectionsTest Method ADistillation 7 to 13Test Method BIon Selective Electrode 14 to 211.2 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
4、the 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 no
5、t affected by the interferencescommon to colorimetric procedures. Concentrations of fluoridefrom 0.1 to 1000 mg/L may be measured.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address
6、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 determine the applica-bility of regulatory limitations prior to use. For a specificprecautionary statement, see 12.1.2.1.6 Former
7、 Test Method A, SPADNS PhotometricProcedure, was discontinued. Refer to Appendix X1 forhistorical information.2. Referenced Documents2.1 ASTM Standards:3D1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precis
8、ion and Bias ofApplicable Test Methods 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 fo
9、r Water Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard, refer toTerminologies D1129 and D4127.4. Significance and Use4.1 Simple and complex fluoride ions are found in naturalwaters. Fluoride forms complexing ions with silicon,aluminum, and boron. These com
10、plexes may originate from theuse of fluorine compounds by industry.4.2 Fluoridation of drinking water to prevent dental caries ispracticed by a large number of communities in this country.Fluoride is monitored to assure that an optimum treatmentlevel, usually near 1 mg/L, is maintained.5. Purity of
11、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 Analytical1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility
12、of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved June 15, 2016. Published June 2016. Originallyapproved in 1951. Last previous edition approved in 2010 as D1179 10. DOI:10.1520/D1179-16.2Bellack, E., “Simplified Fluoride Distillation Method,” Journal of the AmericanW
13、ater 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 information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Ch
14、anges section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Reagents of the American Chemical Society, where suchspecifications are available.4Other grades may be used, pro-vided it is first ascert
15、ained that the reagent is of sufficientlyhigh purity to permit 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 D1193. Other reagent water typesmay
16、be used provided it is first ascertained that the water is ofsufficiently 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.6. Sampling6.1 Collect the sample in accordan
17、ce with Practice D1066or Practices D3370, as applicable.TEST METHOD ADISTILLATION7. Scope7.1 This test method is applicable to the accurate determi-nation of fluoride ion in water, including most wastewaters.Samples that may require distillation include high concentra-tions of fluoborate or fluobori
18、c acid (such as electroplatingwastes), and samples which contain aluminum, silica, or iron(see Table 1).Anions such as chloride, bromide, iodide, sulfate,bicarbonate, nitrate, phosphate and acetate do not interfere withISE measurement unless present at greater than about1%anddo not necessitate disti
19、llation. This test method may not beapplicable to concentrated brines and oily wastes.7.2 This test method was tested on reagent water andwastewater. It is the users responsibility to ensure the validityof this test method for waters of untested matrices.8. Summary of Test Method8.1 The fluoride is
20、distilled as hydrofluosilicic acid and isdetermined by the ion selective electrode method.9. Interferences9.1 In sample distillation, interferences may be experienceddue to the following factors.9.1.1 Aluminum in excess of 300 mg/L and silicon dioxideas colloidal silica in excess of 400 mg/L will ho
21、ld 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 with300 to 400 mL of water and the washwater added to thedistillate. The distillate may then be diluted
22、 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 will cause bumping in thedistillation flask. Dilution of the sample with fluoride-freewater to a lesser
23、-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 may prevent accurate measurement of fluoride. Suchsamples should be extracted initially with a suitab
24、le 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 AssemblyGlassware consisting of a 1-L,round bottom, borosilicate boiling flask, an adapter with athermo
25、meter 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.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC.
26、For suggestions 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.TABLE 1 Allowable In
27、terference Levels with Selective IonElectrode and BufferAInterfering IonMaximum Allowable Concentration at1.0 mg/L FAl+30.5Si+450Fe+365ARefer to 16.2 for description of interfering cations.AHeating mantle (quartz).BRound-bottom flask, 1000 mL.CAdapter with thermometer opening.DThermometer, 200C.ECon
28、necting tube.FGraham condenser, 300 mm.GVessel, calibrated at 300 mL.FIG. 1 Distillation Assembly for Fluoride IsolationD1179 16211. Reagents11.1 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 soluti
29、on to 1.0 L withwater. Store in borosilicate glass or polyethylene. Alternately,commercially prepared fluoride standards of appropriateknown purity may be used.11.2 Sulfuric Acid (H2SO4), Concentrated (sp gr 1:84).12. Procedure12.1 Distillation:12.1.1 Place 400 mL of water in the distilling flask an
30、d add200 mL of concentrated H2SO4(sp gr 1.84). Observe the usualprecautions while mixing the H2SO4by slow addition of theacid accompanied by constant swirling. Add sufficient boilingstones5and assemble the apparatus as shown in Fig. 1. Heat thesolution in the flask, preferably with an electric heati
31、ng mantle,until the temperature of the contents reaches exactly 180C. (Aquartz heating 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
32、this step, servesto adjust the acid-water ratio for subsequent distillations.12.1.2 CautionCool 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.12.1.3 Collect the distillate in any
33、 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 Samples containing chlorides less than about1%donot interfere with ISE measurements.12.1.5 The acid-water dis
34、tilling solution may be used re-peatedly until the buildup of interference materials equals theconcentration given in Section 9.12.2 AnalysisUse Test Method B (Ion Selective Elec-trode) with the buffer solution described in 18.1.13. Precision and Bias13.1 The precision and bias for Test Method A, sh
35、own inTable 2 and Table 3 were determined using distillation fol-lowed by an ion selective electrode finish. Four concentrationsand three replicates were provided by six laboratories forreagent water and wastewater.13.2 Precision and bias for this test method conform toPractice D2777 77, which was i
36、n place at the time ofcollaborative testing. Under the allowances made in 1.4 ofPractice D2777 13, these precision and bias data do meetexisting requirements for interlaboratory studies of CommitteeD19 test methods.TEST METHOD BION SELECTIVE ELECTRODE14. Scope14.1 This test method is applicable to t
37、he measurement offluoride ion in finished waters, natural waters, and mostindustrial wastewaters. With this test method, distillation iseliminated and concentrations of fluoride from 0.1 to 1000mg/L may be measured. Concentrated solutions of fluoborateor fluoboric acid, such as in electroplating was
38、tes, should bedistilled or tested using a fluoroborate ISE. Samples whichcontain aluminum, silica, or iron may require distillation (seeTable 1). Anions such as chloride, bromide, iodide, sulfate,bicarbonate, nitrate, phosphate, and acetate typically do notinterfere unless present at greater than ab
39、out1%ormore.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 this test methodfor waters of untested matrices.15. Summary of Test Method15.1
40、The fluoride is determined potentiometrically using anion selective fluoride electrode in conjunction with a standardsingle junction, sleeve-type reference electrode or a combina-tion fluoride electrode. Use the electrode(s) with a pH meterhaving an expanded millivolt scale, or an ISE meter having a
41、direct concentration readout.5Glass beads must be of a soft glass (rather than borosilicate). Use about 12beads. Soft beads will provide silica to the fluoride and protect the distillation flask.TABLE 2 Determination of PrecisionFinal Statistics for TestMethod ANOTE 1Precision of Test Method A was d
42、etermined from round 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 0.09
43、2 0.070ASo0.018 0.013 0.017 0.030AACalculated with outlier point removed from data base.TABLE 3 Determination of Bias for Test Method ANOTE 1Bias of Test Method A was determined from round robin datausing distillation with ion selective electrode finish.Amountaddedmg/LMean re-coverymg/LBias % BiasSt
44、atisticallysignificantat 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 % yesD1179 16315.2 The fluoride el
45、ectrode consists of a lanthanum fluoridecrystal across which a potential is developed by fluorideions.6,7The cell may be represented by Ag/AgCl, Cl (0.3), F(0.001) LaF3/test solution/KCl/AgCl/Ag.15.3 The electrode(s) is calibrated in known fluoridesolutions, and the concentrations of unknowns are de
46、terminedin solutions with the same background. Samples and standardsshould be measured at the same temperature.15.4 Standards and samples are diluted with an ionicstrength adjustor that also minimizes possible interferencesfrom hydroxide and low levels of aluminum and iron.16. Interferences16.1 Extr
47、emes 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 1). The addition of the buffer solution, 1
48、8.1,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
49、 usually encountered in other testmethods, such as sulfate, chloride, or phosphate, do not affectthis test method.17. Apparatus17.1 pH Meter, with expanded millivolt scale or selective-ion meter.17.2 Fluoride Ion Selective Electrode, half-cell or combina-tion electrode.17.3 Reference Electrode, single-junction sleeve-type (whenusing fluoride half-cell).17.4 Mixer, magnetic, with a TFE-fluorocarbon coated stir-ring bar or motorized stirrer.18. Reagents18.1 Buffer Solution (pH from 5.0 to 5.5)To approxi-mately 500 mL of water,
