1、Designation: D 4765 03Standard Test Method forFluorides in Workplace Atmospheres1This standard is issued under the fixed designation D 4765; 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 par
2、entheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the simultaneous collection andseparate measurements of gaseous and particulate fluoridefound in certain industrial workpla
3、ces. The gaseous inorganicfluorides collected are reported in terms of fluoride; theprocedure is not applicable to the collection or analysis of otherfluoride-bearing gases (for example, fluorocarbon or fluorosul-fur compounds). This test method covers sample collection,preparation, and fluoride mea
4、surement.1.2 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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Ref
5、erenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 1357 Practice for Planning the Sampling of the AmbientAtmosphereD 5337 Practice for Flow Rate for Calibration of PersonalSampling Pumps3. Terminology3.1 Defi
6、nitionsFor definitions of terms used in this testmethod, refer to Terminology D 1356.4. Summary of Test Method4.1 Particulate material from a measured volume of air iscollected by means of a membrane filter. Gaseous fluoride,from the sample of air, is absorbed by an alkali-impregnatedcellulose pad p
7、laced immediately behind the membrane filter.The membrane filter and collected solids are made alkaline,ashed, and the residue fused with additional alkali. Finally, thefluoride is determined in a solution of the melt by use of afluoride ion-selective electrode. Gaseous fluoride is determinedin an a
8、queous extract of the cellulose pad, also by means of thefluoride ion-selective electrode.5. Significance and Use5.1 The capability of this test method to collect and quan-titate both particulate and gaseous fluorides over the rangesnormally encountered in industrial atmospheres makes it ap-plicable
9、 for industrial hygiene evaluation and control purposes.The recommended range of this test method is from 0.005 to 5mg F/m3air.6. Interferences6.1 Because an ion-selective electrode responds to ionicactivity, insoluble and complex forms of fluoride must bereleased by appropriate combinations of fusi
10、on, adjustment ofpH, and addition of complexing agents.6.2 Acidity (pH) and ionic strengths of fluoride standardsolutions must be matched to those of samples.6.3 Temperature of sample and standard solutions must becontrolled within 6 2C.7. Apparatus7.1 Personal Sampling Pump, Equipped with a flow-mo
11、nitoring device (rotameter, critical orifice) or a constant-flow device capable of drawing 2 L/min of air through the0.8-m membrane filter and pad for a period of 8 h.7.2 Filter HolderPlastic holders of the preloaded personalmonitor type, that accept filters of 37-mm diameter, arepreferred. The hold
12、er is to be numbered for identification.7.3 Membrane Filter, of mixed-cellulose esters, 0.8-mpore size, and of diameter to fit the filter holder (see 7.2).7.4 Cellulose Pad, of size to fit the filter holder (see 7.2).The pad is commercially available as a plain, unpregnated pador as an alkali-impreg
13、nated pad.7.5 Crucibles, 20-mL, nickel, Inconel,3or platinum.7.6 Fluoride Ion-Selective Electrode.7.7 Reference Electrode, calomel type, preferably combinedwith the fluoride ion-selective electrode.1This test method is under the jurisdiction of ASTM Committee D22 onSampling and Analysis of Atmospher
14、es and is the direct responsibility of Subcom-mittee D22.04 on Workplace Atmospheres.Current edition approved April 10, 2003. Published June 2003. Originallyapproved in 1988. Last previous edition approved in 1998 as D 4765 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orc
15、ontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Inconel is a trademark for a group of corrosion-resistant alloys of nickel andchromium.1Copyright ASTM International, 100 Barr Harbor
16、 Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.8 Electrometer or Expanded Scale pH Meter, with amillivolt scale for measurement of potentials.7.9 Magnetic Stirrer.7.10 Plastic Beakers, 50 and 100-mL capacities.7.11 Beakers, 250-mL capacity.7.12 Volumetric Flasks, 100-mL capac
17、ity.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.48
18、.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean Type I Reagent Waterconforming to Specification D 1193.8.3 Alkaline Fixative SolutionDissolve 25 g of sodiumcarbonate (Na2CO3) in water, add 20 mLglycerol, and dilute to1L.8.4 Buffer Solution (ALCOA)Dissolve
19、 60 g of citric acidmonohydrate (C2H8O7H2O), 210 g of sodium citrate(Na3C6H5O72H2O) and 53.5 g of ammonium chloride(NH4Cl) in 500 mLwater.Add 67 mLof ammonium hydroxide(NH4OH) (sp gr = 0.90) and dilute to 1 L with water.8.5 Fluoride Solution, Standard (100 g/mL)Dissolve0.2211 g sodium fluoride (NaF,
20、 dried at 105C for 2 h) in waterand dilute to volume in a 1-L volumetric flask.8.6 Ethanol, DenaturedFormula 30 denatured alcohol issatisfactory.8.7 Borate-Carbonate Fusion MixtureIntimately mix a1+2 (w/w) combination of sodium tetraborate (Na2B4O7) andsodium carbonate (Na2CO3).8.8 Hydrochloric Acid
21、 (1+1)Mix one part hydrochloricacid to one part distilled water as a solution.9. Sampling9.1 For general information on sampling, refer to PracticeD 1357.9.2 Equip the worker whose exposure is to be evaluatedwith a personal monitor connected by a 75-cm length of hoseto a belt-supported sampling pump
22、. Attach the monitor to theworkers collar and remove the plug for closed-face sampling.Air is drawn through the filter at the calibrated rate ofapproximately 2.0 L/min and maintained at that rate byoccasional checking and adjustment. On termination of sam-pling, note the duration of sampling, reseal
23、 the monitor andreturn the monitor to the laboratory. Filter a minimum airsample of 250 L.9.3 Total particulate loading may be determined, if required,by pre- and post-weighing of the membrane filter.10. Preparation of Monitors10.1 Disassemble the personal monitor (see 7.2), removingthe membrane fil
24、ter and cellulose pads. Moisten the pad with ameasured volume of alkaline fixative solution (see 8.3); 0.8 mLis required for a pad of 37-mm diameter. Dry the pad at 105Cfor 30 to 45 min.NOTE 1Preparation of alkali-impregnated pads must be carried out ina low-fluoride environment with minimum exposur
25、e.10.2 Reassemble the filter monitor, inserting an impreg-nated pad and membrane filter, and closing with the filterretaining ring and front cover. Seal the assembly against airleakage by a wrap of masking tape or cellulose shrink bands,covering the crevice between the retaining ring and back cover.
26、Close the inlet and outlet openings of the monitor with plasticplugs.11. Calibration of the Personal Monitoring Pump11.1 Refer to Practice 5337.11.2 Select several of the prepared monitors at random forcalibration of air flow rate with the personal sampling pump(see 7.1). Connect the monitor exit to
27、 the sampling pump bymeans of a 75-cm length of hose. Connect the flowmeter(preferably a bubble flowmeter, magnehelic flowmeter, or wettest meter) to the inlet port of the monitor. Start the pump andadjust its rate, noting the position of the rotameter ball when asampling rate of about 2.0 L/min is
28、indicated by use of thecalibration flowmeter and a timer.NOTE 2Calibration of pumps with monitors in both in-line andopen-face modes showed no significant difference.12. Calibration12.1 Fluoride Standards, ParticulateAdd 1.0 g borate-carbonate fusion mixture to each of four 250-mL beakerscontaining
29、10 mL of water and 50 mL of buffer solution (8.4).Add a few drops of (1 + 1) hydrochloric acid (see 8.8) and addvarious size aliquots (1, 5, 10, and 25 mL) of 100 g/mLstandard fluoride solution (see 8.5) to produce a series ofworking standards (1, 5, 10, and 25 g/F/mL). Transfer to a100-mL volumetri
30、c flask, and dilute to volume with water.NOTE 3These standards may be stored for several months in tightlycapped polyethylene bottles, under refrigeration.12.2 For calibration of the electrode, pour about 20 mL ofthe working standard solution into a plastic beaker containinga TFE-fluorocarbon-coated
31、 stirring bar. Adjust solution towithin 6 2C of an arbitrarily selected standard temperature.Insert the fluoride and reference electrodes into the constantlystirred solution and measure the potential after 2 min. Repeatfor each of the working standards.12.3 Prepare a calibration graph, on three-cycl
32、e semilogpaper, relating potential, in mV (linear scale), to concentrationof fluoride in m/mL (log scale). Reproducibility of each pointshould be 6 1 mV.Alinear calibration graph is obtained in the0.5 to 25 g/mL range, with a slope of between 57 and 59 mVper tenfold change in fluoride concentration.
33、NOTE 4If solutions containing less than 0.5 g/mL are measured,additional standards must be prepared since the calibration graph is notlinear at low fluoride concentrations.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the t
34、esting 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. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D476503212.4 Fluoride Standards, GaseousInto
35、each of four100-mL volumetric flasks, place 10 mL of water and 50 mL ofbuffer solution (see 8.4). Add various size aliquots (1, 5, 10,and 25 mL) of 100 g/mL standard fluoride solution (see 8.5)to produce a series of working standards (1, 5, 10, and 25 gF/mL). Dilute to volume with water.12.5 A separ
36、ate calibration graph for gaseous fluoride isprepared from potential measurements of these standards (see12.4), by the same procedure as used for particulate fluorides(see 12.2 and 12.3).NOTE 5The analysis of control standards and blanks is recommendedto determine recovery levels.13. Procedure13.1 P
37、articulate FluorideCarefully remove the mem-brane filter from the filter holder and place it in a nickel,Inconel, or platinum crucible containing 0.5 g borate-carbonatefusion mixture. Transfer any dust from inside the filter coverand retaining ring to the crucible. Drench the filter with ethanoland
38、ignite with a small gas flame. Heat the residue to fusiontemperature for 1 to 2 min, then cool and dissolve in a few mLof water. Transfer the same solution into a plastic beaker bymeans of 25 mLof buffer solution (see 8.4) followed by a rinseof the crucible with a few drops of (1+1) hydrochloric aci
39、d (see8.8). Dilute to 50 mL in a volumetric flask, mix and bring tostandard temperature. Pour about 20 mL of the solution into aplastic beaker and measure the potential while the electrodesare immersed in the gently stirred solution. Convert potential(mV) to fluoride concentration (g/mL) by means of
40、 thecalibration graph determined from the standard fluoride seriescontaining borate-carbonate flux (see 12.3).NOTE 6During the fusion procedure, do not overheat crucible. Fluo-ride can be lost due to volatilization. The crucible should be heated to adull, red glow until all of the sample is consumed
41、.13.2 Gaseous FluorideTransfer the impregnated cellulosepad to a 100-mL plastic beaker containing 25 mL water and 25mLbuffer solution (see 8.4).Allow the pad to soak for about 30min with sufficient stirring to reduce it to a pulp. Bring thesolution to standard temperature, insert the electrodes, and
42、measure potential of the gently stirred mixture after 2 min.Convert potential (mV) to fluoride concentration (g/mL) bymeans of the calibration graph determined from the standardfluoride series (see 12.5).14. Calculations14.1 The concentration of particulate fluorides in air, inte-grated over the sam
43、pling period, is calculated as follows:Cp5 0.05 3C1V(1)where:Cp= concentration of particulate fluoride, in mg/m3,0.05 = conversion factor for a 50-mL sample size and theconversion of micrograms to milligrams,C1= concentration of fluoride in particulate sample so-lution in g/mL, andV = volume of air
44、sample in m3, corrected to 25C and760 torr.14.2 The concentration of gaseous fluoride in air, integratedover the sampling period, is calculated as follows:Cg5 0.05 3C2V(2)where:Cg= concentration of gaseous fluoride in mg/m3,0.05 = conversion factor for a 50-mL sample size and theconversion of microg
45、rams to milligrams,C2= concentration of fluoride in gaseous sample solu-tion in g/mL,V = volume of air sample in m3, corrected to 25C and760 torr.14.3 If desired, gaseous fluoride concentration in air, inmg/m3, may be converted to equivalent concentration ex-pressed as parts per million as follows:C
46、g, mg/m33 1.29 5 Cg, ppm (3)15. Precision and Bias15.1 PrecisionRepeatability (Both single-analyst andoverall):15.1.1 Four levels of gaseous fluoride were generated andcollected on a treated filter: 0.030, 0.295, 1.49, and 2.90 mgfluoride/sample. Each concentration was analyzed in triplicateby eight
47、 participating laboratories. The single operator relativestandard deviation (RSD) varied from 10.3 % to 2.8 % with apooled relative standard deviation of 7.5 %. The overallrelative standard deviation for the eight laboratories variedfrom 24.8 % to 7.6 % with a pooled relative standard deviationof 16
48、.0 %.515.1.2 Three levels of particulate fluoride were generated byweighing a standard sample and encapsulating the sample ontoa filter: 0.742, 1.48, and 2.41 mg fluoride/sample. Eachconcentration was analyzed in triplicate by eight participatinglaboratories. The single operator relative standard de
49、viation(RSD) varied from 13.9 % to 4.4 % with a pooled relativestandard deviation of 9.2 %. The overall relative standarddeviation for the eight laboratories varied from 31.5 % to21.2 % with a pooled relative standard deviation of 27.2 %.515.2 Bias:5Supporting data are available from ASTM Headquarters. Request RR D22-1015.TABLE 1 Recoveries of Known Amounts of Standard ParticulateFluorideAmountAddedmg FMeanRecovery (x)mg F+Bias +% Bias % RecoveryStatisticallySignificant(95 %ConfidenceLevel)0.742 0.575 0.167 22.5 77.5 Yes1.48 1.15 0.33
