环境实验不确定度评定

TR537Approved2003-05PublishedbyNordtestPhone:[phone]Fax:[phone]Tekniikantie12E-mail:[e-mail]:–02150EspooFinlandHANDBOOKFORCALCULATIONOFMEASUREMENTUNCERTAINTYINENVIRONMENTALLABORATORIESBertilMagnussonTeemuNäykkiHåvardHovindMikaelKrysellNTTECHNREPORT537Approved2003-05Authors:BertilMagnusson1TeemuNäykki2HåvardHovind3MikaelKrysell4NORDTESTprojectnumber:1589-02Institution:1)SP,Sweden,2)SYKE,Finland,3)NIVA,Norway,4)EurofinsA/S,DenmarkTitle(English):Title(Original):HandbookforCalculationofMeasurementUncertaintyinEnvironmentalLaboratoriesAbstract:ThishandbookiswrittenforenvironmentaltestinglaboratoriesintheNordiccountries,inordertogivesupporttotheimplementationoftheconceptofmeasurementuncertaintyfortheirroutinemeasurements.Theaimistoprovideapractical,understandableandcommonwayofmeasurementuncertaintycalculations,mainlybasedonalreadyexistingqualitycontrolandvalidationdata,accordingtotheEuropeanaccreditationguideline/12/,theEurolabTechnicalReportNo.1/3/andtheISO/DTS21748Guide/8/.NordtesthassupportedthisprojecteconomicallyinordertopromoteandenhanceharmonisationbetweenlaboratoriesontheNordicmarket.Practicalexamples,takendirectlyfromtheeverydayworldofenvironmentallaboratories,arepresentedandexplained.However,theapproachisverygeneralandshouldbeapplicabletomosttestinglaboratoriesinthechemicalfield.Thehandbookcoversallstepsintheanalyticalchainfromthearrivalofthesampleinthelaboratoryuntilthedatahasbeenreported.Itisimportanttonoticethatvitalpartsofthetotalmeasurementuncertaintyarenotincluded,e.g.sampling,sampletransportationandpossiblegrosserrorsduringdatastorage/retrieval.Therecommendationsinthisdocumentareprimarilyforguidance.Itisrecognisedthatwhiletherecommendationspresenteddoformavalidapproachtotheevaluationofmeasurementuncertaintyformanypurposes,othersuitableapproachesmayalsobeadopted–seereferencesinSection9.EspeciallytheEURACHEM/CITAC-Guide/2/isusefulincaseswheresufficientpreviousdataisnotavailable,andthereforethemathematicalanalyticalapproachaccordingtoGUM/1/withalldifferentstepsistobeused.Basicknowledgeintheuseofqualitycontrolandstatisticsisrequired.Inordertomakeitpossibleforthereadertofollowthecalculations,somerawdataisgiveninappendices.TechnicalGroup:ExpertGroupQualityandMetrologyISSN:0283-7234Language:EnglishPages:41Class(UDC):620.1Keywords:handbook,laboratories,environmental,testing,measurements,uncertainty,chemicalPublicationcode:Distributedby:NORDTESTTekniikantie12FIN-02150ESPOOFinlandReportInternetaddress:äykki,SYKE,FinlandHåvardHovind,NIVA,NorwayMikaelKrysell,EurofinsA/S,DenmarkDrawingsbyPetterWang,NIVA,NorwayValuablecommentsonthecontentshavebeenprovidedby:RolfFlykt,SwedenIrmaMäkinen,FinlandUllaO.Lund,DenmarkSteveEllison,UKContents:1DEFINITIONSANDABBREVIATIONS......................................................12INTRODUCTION............................................................................................32.1SCOPEANDFIELDOFAPPLICATION..........................................................................32.2COMMENTTOCUSTOMERS.......................................................................................32.3ABOUTMEASUREMENTUNCERTAINTY....................................................................43CALCULATIONOFEXPANDEDUNCERTAINTY,U-OVERVIEW......63.1CUSTOMERNEEDS....................................................................................................73.2FLOWSCHEMEFORUNCERTAINTYCALCULATIONS..................................................73.3SUMMARYTABLEFORUNCERTAINTYCALCULATIONS.............................................94REPRODUCIBILITYWITHIN-LABORATORY-u(RW)..........................104.1CUSTOMERDEMANDS............................................................................................104.2CONTROLSAMPLECOVERINGTHEWHOLEANALYTICALPROCESS..........................104.3CONTROLSAMPLEFORDIFFERENTMATRICESANDCONCENTRATIONLEVELS........114.4UNSTABLECONTROLSAMPLES...............................................................................125METHODANDLABORATORYBIAS–u(BIAS)...................................155.1CERTIFIEDREFERENCEMATERIAL.........................................................................155.2INTERLABORATORYCOMPARISONS........................................................................175.3RECOVERY.............................................................................................................186REPRODUCIBILITYBETWEENLABORATORIES,SR...........................196.1DATAGIVENINSTANDARDMETHOD......................................................................196.2DATAFROMINTERLABORATORYCOMPARISONS....................................................197EXAMPLES...................................................................................................217.1AMMONI