BS ISO 14965-2000 Ambient air Determination of total non-methane organic compounds Cryogenic preconcentration and direct flame ionization detection method《环境空气 全部无甲烷有机化合物的测定 低温预浓缩和.pdf

1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS ISO 14965:2000 ICS 13.

2、040.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Ambient air Determination of total non-methane organic compounds Cryogenic preconcentration and direct flame ionization detection methodThis British Standard, having been prepared under the direction of the Health and Envi

3、ronment Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 May 2000 BSI 05-2000 ISBN 0 580 34738 9 BS ISO 14965:2000 Amendments issued since publication Amd. No. Date Comments National foreword This British Standard reproduces verbatim ISO 1496

4、5:2000 and implements it as the UK national standard. The UK participation in its preparation was entrusted by Technical Committee EH/2, Air quality, to Subcommittee EH/2/3, Ambient atmospheres, which has the responsibility to: aid enquirers to understand the text; present to the responsible interna

5、tional/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to it

6、s secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Elec

7、tronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This d

8、ocument comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 21 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued.Referencenumber ISO14965:2000(E) INTERNATIONAL STANDARD ISO 14965 F

9、irstedition 2000-03-15 AirqualityDeterminationoftotalnon- methaneorganiccompoundsCryogenic preconcentrationanddirectflame ionizationdetectionmethod Qualit de lair Dosage des composs organiques non mthaniques totaux Mthode par prconcentration cryognique et ionisation slective directe dans la flammeIS

10、O14965:2000(E) ii ISO14965:2000(E)iii Contents Page Foreword.iv Introduction.v 1 Scope1 2 Normativereferences1 3 Termsanddefinitions.2 4 Descriptionofthemethod2 4.1 Sampling.2 4.2 Analysis2 5 Interferences3 6 Apparatus.3 6.1 Samplecollectionsystem(Figure1)3 6.2 Sample-canistercleaningsystem(Figure2)

11、.4 6.3 Analyticalsystem(Figure3)6 7 Reagentsandmaterials9 8 Canistercleanupandpreparation9 9 Sampling.10 9.1 General10 9.2 Samplecollection11 10 Sampleanalysis.12 10.1 Assembly12 10.2 Analyticalsystemleakcheck.12 10.3 Samplevolumedetermination12 10.4 Analyticalsystemdynamiccalibration.13 10.5 Analys

12、isprocedure(seeFigure3)14 11 PerformancecriteriaandQualityAssurance16 11.1 General16 11.2 Standardoperatingprocedure(SOP)17 11.3 Methodsensitivity,accuracyandprecision.17 12 Methodmodification18 12.1 Samplemeteringsystem18 12.2 Canistercleaning.18 12.3 FIDsystem18 12.4 Range18 12.5 Alternativecryoge

13、nictrappingandheatingsystems18 12.6 Sub-atmosphericpressurecanistersampling.18 12.7 Alternativesamplingsystem18 13 Precisionandaccuracy.19 13.1 Precision.19 13.2 Accuracy.19 AnnexA(informative)ExampleofpressurizedcanisterSamplingDataSheet20 Bibliography21ISO14965:2000(E) iv Foreword ISO(theInternati

14、onalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISO memberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnical committees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishedhas therighttoberepresentedon

15、thatcommittee.Internationalorganizations,governmentalandnon-governmental,in liaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnical Commission(IEC)onallmattersofelectrotechnicalstandardization. InternationalStandardsaredraftedinaccordancewiththerulesgiveninthe

16、ISO/IECDirectives,Part3. DraftInternationalStandardsadoptedbythetechnicalcommitteesarecirculatedtothememberbodiesforvoting. PublicationasanInternationalStandardrequiresapprovalbyatleast75%ofthememberbodiescastingavote. AttentionisdrawntothepossibilitythatsomeoftheelementsofthisInternationalStandardm

17、aybethesubjectof patentrights.ISOshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights. InternationalStandardISO14965waspreparedbyTechnicalCommitteeISO/TC146, Air quality, Subcommittee SC3, Ambient atmospheres. AnnexAofthisInternationalStandardisforinformationonly.ISO14965:2000(E)v Introdu

18、ction Accuratemeasurementsofambientconcentrationsoftotalnon-methanevolatileorganiccompounds(NMVOC)are importantforthecontrolofphotochemicalsmogbecausetheseorganiccompoundsareprimaryprecursorsof atmosphericozoneandotheroxidants. TheNMVOCconcentrationstypicallyfoundaturbansitesmayrangeupto1ppmCto3ppmC

19、(seedefinition3.4) orhigher.Inordertodeterminetransportofprecursorsintoanarea,measurementofNMVOCupwindofthearea maybenecessary.RuralNMVOCconcentrationsoriginatingfromareasfreefromNMVOCsourcesarelikelyto measurelessthanafewtenthsof1ppmC. Conventionalmethodsthatdependongaschromatographyandqualitativea

20、ndquantitativespeciesevaluationare excessivelydifficultandexpensivetooperateandmaintain.ThemethoddescribedinthisInternationalStandard involvesasimple,cryogenicpreconcentrationprocedurewithsubsequentdirectdetectionwiththeflameionization detector(FID).Themethodissensitiveandprovidesaccuratemeasurement

21、sofambienttotalNMVOC concentrationswherespeciesdataarenotrequired. ThisInternationalStandardisintendedforanalysisofairsamplesfromsamplingcanistersandhasnotbeen designedforcontinuousambientairmonitoring. AnotherapplicationofthisInternationalStandardisthemonitoringofthecleanlinessofcanistersandscreeni

22、ngof canistersamplespriortoanalysis. Collectionofambientairsamplesinpressurizedcanistersprovidesthefollowingadvantages: convenientintegrationofambientsamplesoveraspecifictimeperiod; capabilityofremotesamplingwithsubsequentcentrallaboratoryanalysis; abilitytoshipandstoresamples,ifnecessary; analysiso

23、fsamplesfrommultiplesiteswithoneanalyticalsystem; collectionofreplicatesamplesforassessmentofmeasurementprecision; specifichydrocarbonanalysismaybeperformedwiththesamesamplesystem.INTERNATIONALSTANDARD ISO14965:2000(E)1 AirqualityDeterminationoftotalnon-methaneorganic compoundsCryogenicpreconcentrat

24、ionanddirectflame ionizationdetectionmethod 1 Scope ThisInternationalStandarddescribesaprocedureforsamplinganddeterminingconcentrationsoftotalnon- methanevolatileorganiccompounds(NMVOC)intheambientatmosphere. ThisInternationalStandarddescribesthecollectionofcumulativesamplesinpassivatedstainlessstee

25、lcanisters andsubsequentlaboratoryanalysis.Itdescribesaprocedureforsamplingincanistersatfinalpressuresabove atmosphericpressure(referredtoaspressurizedsampling).Itemploysacryogenictrappingprocedurefor concentrationoftheNMVOCpriortoanalysis. ThisInternationalStandarddescribesthedeterminationoftheNMVO

26、Cbysimpleflameionizationdetection(FID), withoutthegaschromatographiccolumnsandcomplexproceduresnecessaryforspeciesseparation. ThisInternationalStandardisapplicabletocarbonconcentrationsintherangefrom20ppbCto10000ppbC.See 12.4forproceduresforloweringtherange. Severalvariationstothemethoddescribedinth

27、isInternationalStandardarealsopossible;seeclause12. 2 Normativereferences Thefollowingnormativedocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsof thisInternationalStandard.Fordatedreferences,subsequentamendmentsto,orrevisionsof,anyofthese publicationsdonotapply.However

28、,partiestoagreementsbasedonthisInternationalStandardareencouragedto investigatethepossibilityofapplyingthemostrecenteditionsofthenormativedocumentsindicatedbelow.For undatedreferences,thelatesteditionofthenormativedocumentreferredtoapplies.MembersofISOandIEC maintainregistersofcurrentlyvalidInternat

29、ionalStandards. ISO/TR4227:1989, Planning of ambient air quality monitoring. ISO6141:2000, Gas analysis Requirements for certificates for gases and gas mixtures. ISO6145-1:1986, Gas analysis Preparation of calibration gas mixtures Dynamic volumetric methods Part 1: Methods of calibration. ISO6145-3:

30、1986, Gas analysis Preparation of calibration gas mixtures Dynamic volumetric methods Part 3: Periodic injections into a flowing gas stream. ISO6145-4:1986, Gas analysis Preparation of calibration gas mixtures Dynamic volumetric methods Part 4: Continuous injection methods. ISO6145-6:1986, Gas analy

31、sis Preparation of calibration gas mixtures Dynamic volumetric methods Part 6: Sonic orifices.ISO14965:2000(E) 2 3 Termsanddefinitions ForthepurposesofthisInternationalStandard,thefollowingtermsanddefinitionsapply. 3.1 cryogen refrigerantusedtoobtainverylowtemperaturesinthecryogenictrapsoftheanalyti

32、calsystem NOTE Liquidargon(boilingpoint,87K,atstandardatmosphericpressure)isrecommendedforthemethoddescribedin thisInternationalStandard. 3.2 dynamiccalibration calibrationofananalyticalsystemwithpollutantconcentrationsthataregeneratedinadynamic,flowingsystem NOTE Anexampleofsuchasystemisthequantita

33、tive,flowratedilutionofahigh-concentrationgasstandardwithzero gas. 3.3 totalnon-methanevolatileorganiccompounds: thosecompoundsmeasuredbyaflameionizationdetector,excludingmethane,andcompoundswithvapour pressureabove10 -2 kPa,recoveredfromthecanister 3.4 partspermillionbillionoforganiccarbon ppmCppbC

34、 concentrationunit,asdetectedbytheFID,equivalenttopartspermillionbillionbyvolumemultipliedbythe numberofcarbonatomsinthecalibrationgasmolecule NOTE Duringcalibrationwithpropane,forexample,itisequivalenttopartspermillionbyvolume(ppm)orpartsperbillion byvolume(ppb),multipliedbythree. 4 Descriptionofth

35、emethod 4.1 Sampling Anairsampleisextracteddirectlyfromtheambientair,collectedintoaprecleanedsamplecanister,and transportedtoalaboratoryforanalysis. 4.2 Analysis Afixed-volumeportionofthesampleairisdrawnfromthecanisteratalowflowratethroughaglass-bead-filledtrap thatiscooledtoapproximately87Kwithliqu

36、idargon.Thecryogenictrapsimultaneouslycollectsandconcentrates theNMVOC,whileallowingthenitrogen,oxygen,methaneandothercompoundstopassthroughthetrapwithout retention.Thesystemisdynamicallycalibratedsothatthevolumeofsamplepassingthroughthetrapdoesnot havetobequantitativelymeasured,butshallbepreciselyr

37、epeatablebetweenthecalibrationandtheanalytical phases. Afterthefixed-volumeairsamplehasbeendrawnthroughthetrap,aheliumcarrier-gasflowisdivertedtopass throughthetrap,intheoppositedirectiontothesampleflow,andintoanFID.Whentheresidualairandmethane havebeenflushedfromthetrapandtheFIDbaselinerestabilizes

38、,thecryogenisremovedandthetemperatureof thetrapisraisedto353Kto363K. Theorganiccompoundspreviouslycollectedinthetraprevolatilizeduetotheincreaseintemperatureandare carriedintotheFID,resultinginaresponsepeakorpeaksfromtheFID.Theareaofthepeakorpeaksis integrated,andtheintegratedvalueistranslatedtoconc

39、entrationunitsviaapreviouslyobtainedcalibrationcurve relatingintegratedpeakareaswithknownconcentrationsofpropane.ISO14965:2000(E)3 ThecryogenictrapsimultaneouslyconcentratestheNMVOCwhileseparatingandremovingthemethanefromair samples.Thetechniqueisthusdirect-readingviaFIDforNMVOCand,becauseoftheconce

40、ntrationstep,itis moresensitivethanconventionalcontinuousNMVOCanalysers. Thesampleisinjectedintothehydrogen-richflameoftheFIDwheretheorganicvaporsburnproducingionized molecularfragments.Theresultingionfragmentsarethencollectedanddetected.Becausethismethodemploysa heliumcarriergas,thedetectorresponse

41、isnearlyunityforallhydrocarboncompounds.Thus,thehistoricalshort- comingofvaryingFIDresponsetoaromatic,olefinicandparaffinichydrocarbonsisminimized.TheFIDismuch lesssensitivetomostorganiccompoundscontainingfunctionalgroupssuchascarbonyls,alcohols,halocarbons, etc. ThisInternationalStandardmayyieldles

42、saccurateresultsforsomehalogenatedoroxygenatedhydrocarbons emittedfromnearbysourcesofindustrialairpollutants. 5 Interferences Inlaboratoryevaluations,moisturehasbeenfoundtocauseapositiveshiftintheFIDbaseline.Theeffectofthis shiftisminimizedbycarefullyselectingtheintegrationterminationpointandadjusti

43、ngthebaselineusedfor calculatingtheareaoftheNMVOCpeaks. Whenusingheliumasacarriergas,FIDresponseisquiteuniformformosthydrocarboncompounds,butthe responsemayvaryconsiderablyforothertypesoforganiccompounds. 6 Apparatus 6.1 Samplecollectionsystem(Figure1) 6.1.1 Samplecanisters. Stainlesssteelelectropol

44、ishedvesselsof4lto6lcapacity,usedforautomaticcollectionofintegratedfieldair sample.Eachcanistershallbestampedonitsframewithauniqueidentificationnumber. 6.1.2 Samplepump. Stainlesssteel,metalbellowstype,capableofatleast200kPamaximumpressure.Ensurethatpumpisfreeof leaks,anduncontaminatedbyoilororganic

45、compounds.Shock-mountthepumptominimizevibration. 6.1.3 Vacuum/pressuregauge,coveringtherange0kPato210kPa. 6.1.4 Solenoidvalve,tocontrolthesampleflowtothecanisterwithnegligibletemperaturerise. 6.1.5 Flowratecontroldevice,e.g.massflowmeter,ofcriticalorificeorshortcapillary,tomaintainthesample flowrate

46、overthesampleperiod. 6.1.6 Particulatematterfilter. Inertin-linefilter,ofporesize2 morless,orothersuitablefilter,usedtofiltertheairsample. 6.1.7 Auxiliaryvacuumpumporblower,capableofdrawingsampleairthroughthesampleinletlinetoreduce inletresidencetimetonogreaterthan10s. 6.1.8 Timer,programmableandele

47、ctricallyconnectedtothesolenoidvalveandpumps,capableofcontrolling thepumpsandthesolenoidvalve. 6.1.9 Sampleinletline,consistingofstainlesssteeltubingcomponents,totransportthesampleairintothe samplesystem.ISO14965:2000(E) 4 Key 1 Sampleinletline 6 Samplecanister(s) 2 Particulatematterfilter 7 Samplep

48、ump 3 Timer 8 Flowcontroldevice 4 Pressuregauge 9 Auxiliaryvacuumpump 5 Solenoidvalve Figure1Samplesystemforautomaticcollectionofintegratedairsamples 6.2 Sample-canistercleaningsystem(Figure2) 6.2.1 Vacuumpump,capableofevacuatingsamplecanister(s)toanabsolutepressureofu2Pa. 6.2.2 Manifold,ofstainless

49、steel,withconnectionsforsimultaneouslycleaningseveralcanisters. 6.2.3 Shut-offvalves(nine). 6.2.4 Pressuregauge,coveringtherange0kPato350kPa,tomonitorzero-airpressure. 6.2.5 Cryogenictraps(two),consistingofU-shapedopentubulartrapscooledwithliquidargon,toprevent contaminationfromback-diffusionofoilfromthevacuumpumpandtoprovideclean,zero-airtothesample canisters. 6.2.6 Vacuumgauge,capableofmeasuringvacuuminthemanifoldtoanabsolutepressureof15Paorless, withscaledivisionsof0,1Pa. 6.2.7 Flowratecontrolvalve,toregulateflowrat