1、Designation: D 3268 91 (Reapproved 2005)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 D 3268; the number immediately follo
2、wing 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 (e) indicates an editorial change since the last revision or reapproval.This standard has been appro
3、ved 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
4、collected 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 withint
5、his 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 themo
6、nthly 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 brackets may be approxi-mate.1.3 This standard does not purport to address all of t
7、hesafety 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:2D 1193 Specification for R
8、eagent WaterD 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 1357 Practice for Planning the Sampling of the AmbientAtmosphereD 3266 Test Method for Automated Separation and Collec-tion of Particulate and Acidic Gaseous Fluoride in theAtmosphere (Double Paper Tape Sampler Method)D
9、3267 Test Method for Separation and Collection of Par-ticulate and Water-Soluble Gaseous Fluorides in the Atmo-sphere (Filter and Impinger Method)D 3269 Test Methods for Analysis for Fluoride Content ofthe Atmosphere and Plant Tissues (Manual Procedures)D 3270 Test Methods for Analysis for Fluoride
10、Content ofthe Atmosphere and Plant Tissues (Semiautomated Method)3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod refer to Terminology D 1356.4. Summary of Test Method4.1 Gaseous fluorides are removed from the air stream byreaction with sodium bicarbonate coated on the i
11、nside 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 (
12、1-4)3. The results arereported as g/m3of gaseous or particulate in air at 25C77F 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 MethodD 3266 or Test Method D 3267 for comparison since
13、 the filter forcollecting particulate precedes the absorbers for gases Mandl and Wein-stein (2) provide some information relative to potential loss of particulatematter.5. Significance and Use5.1 The sodium bicarbonate coated tube filter method pro-vides a means of separating and collecting atmosphe
14、ric gas-eous fluoride and particulate fluoride samples.1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.03 on AmbientAtmospheres and Source Emissions.Current edition approved Oct. 1, 2005. Published January 2006. Ori
15、ginallyapproved in 1973. Last previous edition approved in 2000 as D 3268 - 91 (2000)e1.2For 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 Summa
16、ry page onthe ASTM website.3The boldface numbers in parentheses refer to references at the end of this testmethod.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Since the samples are collected on the dry tube andfilter, the fluo
17、ride 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 employed allow the analysis of the collected fluorideto fractional parts of a microgram per cubic metre on samplesta
18、ken 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 fluoride from the atmosphere. Ifthis potential interference needs to be evaluated, the alkalinityof the water extract m
19、ay 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 calorimetric or electrometricmethods. This is a problem inherent with any collectionmethod for fluoride.7. Apparatus7.1
20、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 HolderConnect the tubing directly to thefilter holder and filter for the collection of particulate matter forparticul
21、ate 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 System:7.3.1 The tube and filter are followed by an air samplingsystem which is capable of sampling at a rate of 15
22、L/min 0.5ft3/min and measuring the total air sampled on a time ratebasis or with a totalizing meter. See Test Method D 3267 forsampling equipment, and the configuration and calibration.7.3.2 The system shall be equipped so that pressure andtemperature of the gas at the point of metering also are kno
23、wnfor correcting sample volumes to standard conditions of 101.3kPa 29.92 in. Hg at 25C 77F.FIG. 1 Sodium Bicarbonate-Coated Glass Tube Illustrating Simple Heating DeviceD 3268 91 (2005)27.3.3 Assemble the sampling system so that the inlet of thetube is 4 to 6 m above ground level (see Practice D 135
24、7) 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 temperature where condensation will not occur.7.5 Configuration of Sampling EquipmentFig. 1 is asketch of the sampling system.
25、 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 fulllength of the tube.7.6.2 The coating shall not contain any large crystals orheavy local deposits which could flake
26、 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 procedure. This is the reagent blank for theprocedure.7.6.4 Prepared tubes shall be sealed until time of use. Serumtube
27、 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 subsequent analytical proceduresto provide a sampling and analytical blank value. Check anymaterials that may come int
28、o contact with the tubes forfreedom from contamination with fluoride. These field blankswill provide the data for the monthly arithmetic mean blankvalue. See Note 3.FIG. 2 Details of Attachment of the Filter Assembly and Limiting Orifice to a Bicarbonate-Coated Tube (7-mm Inside diameter).(A) Polypr
29、opylene Filter Holder. (B) Plastic Female Connector, (C) Limiting OrificeD 3268 91 (2005)3NOTE 3Do not expose the tubes except during sampling.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.All reagents shall conform to the specificationsof the Committee on Analyt
30、ical Reagents of the AmericanChemical Society, where such specifications are available.48.2 Purity of WaterWater shall be reagent water conform-ing to Specification D 1193. Additionally, the water used shallbe demonstrated to contain less than 0.005 g of fluoride/mLby testing with a specific ion ele
31、ctrode 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 %)Prepare a solution of 10 % of potassium hydroxide (KOH) inmethanol by dissolving 100 g of KOH in methanol and di
32、lutingthe 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 diluting the volume to 1 L withmethanol. Mix thoroughly.8.6 Sodium Hydroxide Solution (1.0 N)Dissolve 40.0 g ofsodiu
33、m 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 Solution (5 N)Dissolve 200 g ofNaOH in 250 mL of reagent water in a 1000-mL volumetricflask. Swirl to mix, cool, and di
34、lute 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 mix, cool, and dilute to 1000 mLwith reagent water. Mix thoroughly.8.9 Total Ionic Strength Adjustment Buffer (TISAB
35、)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 (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
36、 (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:9.1.1 Clean the tubes successively with detergent (8.3),alcoholic KOH solution (8.4), and distilled water.9.1.2 Wh
37、ile 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 hot, dry fluoride-free air downwardthrough the tube, while it is hanging in a vertical position.9.1.4 Provide the
38、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 simplify the drying, the hot air stream canbe run through a manifold terminating in several outlet ports.The flow rate thro
39、ugh 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 have been thoroughly rinsed with reagentwater and store in a clean area until used.9.2 Preparation of Filters:9.2.1
40、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 filter holders to the sampling site.Keep the ends sealed until installed at the sampling site.9.3 Air Sampling Procedure:
41、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 using acalibrated limiting orifice or other suitable device to control theflow at this rate (see Fig. 3).9.3.2.1 Record
42、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 and filter assemblies at the end of thesampling period, and return them to the laboratory for analysis.9.4 Coated and
43、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 the analysis in a work area with an atmospherefree of contamination by fluorides.10.1.1 Separate the tubes and the filte
44、r 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 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 hi
45、gh-pressure linear polyethylene(or polypropylene or TFE-fluorocarbon) beaker.10.2.1.3 Analyze using the potentiometric method given inTest Method D 3269.10.2.2 For Semiautomated Analysis: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 dis
46、tilledwater.10.2.2.2 Gently agitate the tube to wet all surfaces andempty the tube into an 8.5-mL sample cup.10.2.2.3 Analyze the sample using the semiautomatedmethod given in Test Method D 3270.10.3 Preparation of Particulate Filters for FluorideAnalysis.4Reagent Chemicals, American Chemical Societ
47、y Specifications, AmericanChemical Society, Washington, DC. 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. Pharmacopeial
48、 Convention, Inc. (USPC), Rockville,MD.D 3268 91 (2005)410.3.1 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(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 solut
49、ion (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 D 3269.10.3.2 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 several seconds witha vortex mixer. Allow to stand for 5 min. Filter samples into an8.5-mL sample cup.10.
