1、Designation: D3268 91 (Reapproved 2011)Standard Test Method forSeparation and Collection of Particulate and GaseousFluorides in the Atmosphere (Sodium Bicarbonate-CoatedGlass Tube and Particulate Filter Method)1This standard is issued under the fixed designation D3268; the number immediately followi
2、ng the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved
3、 for use by agencies of the Department of Defense.1. Scope1.1 The sodium bicarbonate-coated glass tube and mem-brane filter method provides a means for the separation andcollection of gaseous atmospheric forms of fluoride reactivewith sodium bicarbonate and particulate forms of fluoridewhich are col
4、lected by a filter. The test method is applicable to12-h sampling periods, collecting 1 to 500 g of gaseousfluoride at a 15 L/min (0.5 ft3/min) sampling rate or about 0.1to 50 g/m3. The length of the sampling period can therefore beadjusted so that the amount of fluoride collected will fall withinth
5、is range. The actual lower limit of the test method willdepend upon the sensitivity of the analytical method employedand the quality of reagents used in tube preparation andanalysis. It is recommended that the lower limit of detectionshould be considered as two times the standard deviation of themon
6、thly arithmetic mean blank value. Any values greater thanthe blank by less than this amount should be reported as “blankvalue.”1.2 The values stated in SI units are to be regarded asstandard. The inch-pound units in parentheses may be approxi-mate.1.3 This standard does not purport to address all of
7、 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. Referenced Documents2.1 ASTM Standards:2D1193 Specification for
8、Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD1357 Practice for Planning the Sampling of the AmbientAtmosphereD3266 Test Method for Automated Separation and Collec-tion of Particulate and Acidic Gaseous Fluoride in theAtmosphere (Double Paper Tape Sampler Method)D326
9、7 Test Method for Separation and Collection of Par-ticulate and Water-Soluble Gaseous Fluorides in the At-mosphere (Filter and Impinger Method)D3269 Test Methods for Analysis for Fluoride Content ofthe Atmosphere and Plant Tissues (Manual Procedures)3D3270 Test Methods for Analysis for Fluoride Cont
10、ent ofthe Atmosphere and Plant Tissues (SemiautomatedMethod)3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod refer to Terminology D1356.4. Summary of Test Method4.1 Gaseous fluorides are removed from the air stream byreaction with sodium bicarbonate coated on the inside
11、wall ofa borosilicate glass tube (Note 1). Particulate fluorides arecollected on a filter following the tube. The fluoride collectedby the tube is eluted with water or buffer and analyzed forfluoride. The particulate matter collected by the filter is elutedwith acid and analyzed for fluoride (1-4)4.
12、 The results arereported as g/m3of gaseous or particulate in air at 25C(77F) and 101.3 kPa (29.92 in. Hg).NOTE 1Some particulate matter will collect on the wall of the sampletube. If this loss is to be evaluated, use test methods such as Test MethodD3266 or Test Method D3267 for comparison since the
13、 filter for collectingparticulate precedes the absorbers for gases Mandl and Weinstein (2)provide some information relative to potential loss of particulate matter.1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.03
14、on AmbientAtmospheres and Source Emissions.Current edition approved Oct. 1, 2011. Published October 2011. Originallyapproved in 1973. Last previous edition approved in 2005 as D3268 - 91 (2005).DOI: 10.1520/D3268-91R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact A
15、STM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4The boldface numbers in parentheses refer to r
16、eferences at the end of this testmethod.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 The sodium bicarbonate coated tube filter method pro-vides a means of separating and collecting atmospheric gas-eous f
17、luoride and particulate fluoride samples.5.2 Since the samples are collected on the dry tube andfilter, the fluoride may be eluted with a small volume of eluant(see Section 10 for specific instructions on fluoride elution).Elution into a small volume and the sensitivity of the analyticalmethods empl
18、oyed allow the analysis of the collected fluorideto fractional parts of a microgram per cubic metre on samplestaken for a 12-h period.6. Interferences6.1 Significant amounts of acid aerosols or gases mightneutralize or acidify the bicarbonate coating and preventquantitative uptake of gaseous fluorid
19、e from the atmosphere. Ifthis potential interference needs to be evaluated, the alkalinityof the water extract may provide relevant information.6.2 The presence of large amounts of aluminum or certainother metals or phosphates can interfere with subsequentanalyses of the tubes or filters by calorime
20、tric or electrometricmethods. This is a problem inherent with any collectionmethod for fluoride.7. Apparatus7.1 Glass Tubing1200-mm (4-ft) lengths of 7-mm insidediameter borosilicate glass tubing, coated with sodium bicar-bonate, in accordance with the requirements outlined in 7.6.7.2 Filter and Hol
21、derConnect the tubing directly to thefilter holder and filter for the collection of particulate matter forparticulate fluoride analysis (see Fig. 2).NOTE 2Use of material other than that recommended in footnote 6 orFig. 2 will result in gaseous fluoride absorption on the material.7.3 Air Sampling Sy
22、stem:7.3.1 The tube and filter are followed by an air samplingsystem which is capable of sampling at a rate of 15 L/min (0.5ft3/min) and measuring the total air sampled on a time ratebasis or with a totalizing meter. See Test Method D3267 forsampling equipment, and the configuration and calibration.
23、FIG. 1 Sodium Bicarbonate-Coated Glass Tube Illustrating Simple Heating DeviceD3268 91 (2011)27.3.2 The system shall be equipped so that pressure andtemperature of the gas at the point of metering also are knownfor correcting sample volumes to standard conditions of 101.3kPa (29.92 in. Hg) at 25C (7
24、7F).7.3.3 Assemble the sampling system so that the inlet of thetube is 4 to 6 m above ground level (see Practice D1357) andprotected from rain in such a manner as not to interfere with thefree passage of aerosol fluorides.7.4 Light Bulb or Cone Heater, 30-W, installed to heat thegases to a temperatu
25、re where condensation will not occur.7.5 Configuration of Sampling EquipmentFig. 1 is asketch of the sampling system. Other systems that meet therequirements outlined, are also satisfactory.7.6 Criteria for Coating of the Borosilicate Tubes:7.6.1 The coating shall be visible uniform coating on the f
26、ulllength of the tube.7.6.2 The coating shall not contain any large crystals orheavy local deposits which could flake off and be collectedwith the aerosol fluorides.7.6.3 The total coating shall contain less than 1 g offluoride when analyzed without exposure, including all thereagents used in the pr
27、ocedure. This is the reagent blank for theprocedure.7.6.4 Prepared tubes shall be sealed until time of use. Serumtube caps that have been thoroughly rinsed with reagent water(8.2) are recommended for this purpose.7.6.5 Tubes shall be carried through the field procedurewithout exposure and also the s
28、ubsequent analytical proceduresFIG. 2 Details of Attachment of the Filter Assembly and Limiting Orifice to a Bicarbonate-Coated Tube (7-mm Inside diameter).(A) Polypropylene Filter Holder. (B) Plastic Female Connector, (C) Limiting OrificeD3268 91 (2011)3to provide a sampling and analytical blank va
29、lue. Check anymaterials that may come into contact with the tubes forfreedom from contamination with fluoride. These field blankswill provide the data for the monthly arithmetic mean blankvalue. See Note 3.NOTE 3Do not expose the tubes except during sampling.8. Reagents8.1 Purity of ReagentsReagent
30、grade chemicals shall beused in all tests.All reagents shall conform to the specificationsof the Committee on Analytical Reagents of the AmericanChemical Society, where such specifications are available.58.2 Purity of WaterWater shall be reagent water conform-ing to Specification D1193. Additionally
31、, the water used shallbe demonstrated to contain less than 0.005 g of fluoride/mLby testing with a specific ion electrode or by concentration andphotometric analysis.8.3 Detergent Solution, low in fluoride and phosphate forinitial cleaning of the tubes.8.4 Potassium Hydroxide, Alcoholic Solution (10
32、 %)Prepare a solution of 10 % of potassium hydroxide (KOH) inmethanol by dissolving 100 g of KOH in methanol and dilutingthe volume to 1 L with methanol. Mix thoroughly.8.5 Sodium Bicarbonate Solution (5 %)Prepare a solutionof 5 % NaHCO3by dissolving 50 g of sodium bicarbonate(NaHCO3) in water and d
33、iluting the volume to 1 L withmethanol. Mix thoroughly.8.6 Sodium Hydroxide Solution (1.0 N)Dissolve 40.0 g ofsodium hydroxide (NaOH) pellets in 250 mL of reagent waterin a 1000-mL volumetric flask. Swirl to mix, cool, and dilute to1000 mL with reagent water. Mix thoroughly.8.7 Sodium Hydroxide Solu
34、tion (5 N)Dissolve 200 g ofNaOH in 250 mL of reagent water in a 1000-mL volumetricflask. Swirl to mix, cool, and dilute to 1000 mL with reagentwater. Mix thoroughly.8.8 Sulfuric Acid (1.0 N)Add 28 mL of concentratedH2SO4(sp gr 1.84) to 250 mL of reagent water in a 1000-mLvolumetric flask. Swirl to m
35、ix, cool, and dilute to 1000 mLwith reagent water. Mix thoroughly.8.9 Total Ionic Strength Adjustment Buffer (TISAB)Add57 mL of glacial acetic acid, 58 g of sodium chloride (NaCl)and 4.0 g of CDTA (1,2-cyclohexylenedinitrilo)tetraaceticacid to 500 mL of distilled water. Stir and add 5 N NaOHsolution
36、 (8.7) slowly until pH is between 5.0 and 5.5. Cool anddilute to 1 L.8.10 TISAB (1+1)Dilute the full strength TISAB (8.9)with an equal amount of water.8.11 Wetting Agent, for use in the sodium bicarbonatesolution to promote even wetting of the tube.9. Procedure9.1 Coating of Borosilicate Glass Tubes
37、:9.1.1 Clean the tubes successively with detergent (8.3),alcoholic KOH solution (8.4), and distilled water.9.1.2 While still wet from the cleaning, wet the internalsurface of the tube with the 5 % NaHCO3solution (8.5).9.1.3 Allow the tube to drain for about 10 s and dry thecoating rapidly by passing
38、 hot, dry fluoride-free air downwardthrough the tube, while it is hanging in a vertical position.9.1.4 Provide the hot fluoride-free air stream by blowing airthrougha4to8-mesh soda-lime trap and then through 1200mm (4 ft) of coiled copper tubing heated by a small gas burneror heating tape. To simpli
39、fy the drying, the hot air stream canbe run through a manifold terminating in several outlet ports.The flow rate through the system shall be in the order of about3 L/min per tube, and the drying should be complete in about1 min.9.1.5 After the tubes are dry, seal the ends with rubberserum caps which
40、 have been thoroughly rinsed with reagentwater and store in a clean area until used.9.2 Preparation of Filters:9.2.1 Assemble the filters and filter holders in the laboratoryand sealed if not used immediately.9.2.2 Assemble the tubes and filters into a sampling unitprior to taking the tubes and filt
41、er holders to the sampling site.Keep the ends sealed until installed at the sampling site.9.3 Air Sampling Procedure:9.3.1 Take samples for 12-h periods, covering both day andnight conditions, to provide sufficient fluoride for accuratemeasurement.9.3.2 Collect the sample at 15 L/min (0.5 ft3/min) u
42、sing acalibrated limiting orifice or other suitable device to control theflow at this rate (see Fig. 3).9.3.2.1 Record total sample volume with the totalizing gasmeter (7.3.1).9.3.2.2 Record pressure drop and temperature at the meter atthe beginning and end of each sampling period.9.3.3 Cap the tube
43、 and filter assemblies at the end of thesampling period, and return them to the laboratory for analysis.9.4 Coated and exposed tubes and filter holders may besealed and stored indefinitely in a clean, fluoride-free area,prior to analysis.10. Preparation of Samples for Fluoride Analysis10.1 Perform t
44、he analysis in a work area with an atmospherefree of contamination by fluorides.10.1.1 Separate the tubes and the filter assemblies.10.2 Preparation of Tubes for Fluoride Analysis:10.2.1 For Potentiometric Analysis:10.2.1.1 With the tube in a vertical position and the lowerend capped pipet in 5.0 mL
45、 of 1+1 TISAB buffer. (See 8.10.)10.2.1.2 Gently agitate the tube to wet all surfaces andempty the tube into a clean high-pressure linear polyethylene(or polypropylene or TFE-fluorocarbon) beaker.10.2.1.3 Analyze using the potentiometric method given inTest Method D3269.10.2.2 For Semiautomated Anal
46、ysis:10.2.2.1 With the tube in a vertical position, the upper endopen and the lower end capped, pipet in 5.0 mL of distilledwater.5Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the Ameri
47、can 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.D3268 91 (2011)410.2.2.2 Gently agitate the tube to wet all surfaces andempty the tube
48、 into an 8.5-mL sample cup.10.2.2.3 Analyze the sample using the semiautomatedmethod given in Test Method D3270.10.3 Preparation of Particulate Filters for FluorideAnalysis.10.3.1 For Potentiometric Analysis:10.3.1.1 Place particulate filters in clean 15 by 150-mm testtubes. Add 5.0 mL of 1 N H2SO4(
49、see 8.8) and mix for severalseconds with a vortex mixer. Allow to stand for 5 min.10.3.1.2 Add 5 mL of 1 N NaOH solution (8.6) and 10.0 mLof TISAB solution (8.10). Decant into a clean, short form,50-mL beaker made of high-density, linear, polyethylene (orpolypropylene or TFE-fluorocarbon) and dilute with an equalamount of TISAB buffer (8.10).10.3.1.3 Analyze using the potentiometric method, given inMethod D3269.10.3.2 For Semiautomated Analysis:10.3.2.1 Place the particulate filter in a clean test tube, pipetin 5.0 mL of 1 N H2SO4(8.8) and mix for severa
