ASTM_D_4765_-_13.pdf

Designation:D476513Standard Test Method forMeasurement of Fluorides in Workplace Atmospheres byIon-Selective Electrodes1This standard is issued under the fixed designation D4765;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 indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the simultaneous collection andseparate measurements of gaseous fluoride(for example,hydrogen fluoride)and particulate fluoride found in certainindustrial workplaces.The gaseous fluorides and particulatefluorides collected are reported in terms of fluoride.Themethod covers sample collection,preparation,and fluoridemeasurement.1.2 The procedure is not applicable to the collection oranalysis of gaseous fluoro compounds(for example,fluorocar-bon or fluorosulfur compounds).1.3 The values stated in SI units are to be regarded as thestandard.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 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 Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD4840 Guide for Sample Chain-of-Custody ProceduresD5337 Practice for Flow Rate Adjustment of Personal Sam-pling PumpsE1370 Guide for Air Sampling Strategies for Worker andWorkplace Protection3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1356.4.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 placed behind the membrane filter.The mem-brane filter and collected solids are made alkaline,ashed,andthe residue fused with additional alkali.Finally,the fluoride isdetermined in a solution of the melt by use of a fluorideion-selective electrode.Gaseous fluoride is determined in anaqueous 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 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 fusion,adjustment ofpH,and addition of complexing agents.6.2 Filter MaterialsNot all filter materials can be usedeffectively for sampling particulate fluorides in workplace air.Cellulosic membrane filters are the most suitable filter types forsampling of fluorides.Several manufacturers offer mixed-cellulose ester filters commercially;nevertheless it is essentialto check the quality of each filter batch used for sampling.6.3 Acidity(pH)and ionic strengths of fluoride standardsolutions must be matched to those of samples.6.4 Temperature of sample and standard solutions must becontrolled within 62C.7.Apparatus7.1 Personal Sampling Pump,capable of maintaining con-stant air flow(65%)in the range 15 L/min through a filterholder(7.2)containing a 0.8-m pore size cellulosic membranefilter(7.3)and cellulose pad(7.4)for a period of up to 8 hours.1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.04 on Workplace AirQuality.Current edition approved April 1,2013.Published April 2013.Originallyapproved in 1988.Last previous edition approved in 2008 as D4765 03(2008).DOI:10.1520/D4765-13.2For 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 Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.2 Filter HolderFor sampling of inhalable fraction ofaerosols,of suitable diameter for the filters(for example,37-mm;see 7.3).The holder shall be numbered for identifica-tion.7.3 Membrane Filter,of mixed-cellulose esters(MCE),0.8-m pore size,and of diameter to fit the filter holder(see7.2).7.4 Cellulose Pad,of size to fit the filter holder(see 7.2).The pad is commercially available as a plain,unimpregnatedpad or impregnated with alkali(8.3).7.5 Crucibles,20-mL,nickel,platinum,or suitable alloys ofnickel and chromium.7.6 Fluoride Ion-Selective Electrode.7.7 Reference Electrode,calomel type,preferably combinedwith the flu