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
