EN 13806-2002 en Foodstuffs - Determination of trace elements - Determination of mercury by cold-vapour atomic absorption spectrometry (CVAAS) after pressure digestion《食品 痕量元素测定 加压.pdf

1、BRITISH STANDARD BS EN 13806:2002 Foodstuffs Determination of trace elements Determination of mercury by cold-vapour atomic absorption spectrometry (CVAAS) after pressure digestion The European Standard EN 13806:2002 has the status of a British Standard ICS 67.050 BS EN 13806:2002 This British Stand

2、ard, having been prepared under the direction of the Consumer Products and Services Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 10 September 2002 BSI 10 September 2002 ISBN 0 580 40367 X National foreword This British Stan

3、dard is the official English language version of EN 13806:2002 The UK participation in its preparation was entrusted to Technical Committee AW/-/3, Horizontal analysis, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary.

4、 Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue o

5、r of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the tex

6、t; present to the responsible international/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. Summary of pages This document comprises a front cov

7、er, an inside front cover, the EN title page, pages 2 to 11 and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN13806 August2002 ICS

8、67.050 Englishversion FoodstuffsDeterminationoftraceelementsDeterminationof mercurybycoldvapouratomicabsorptionspectrometry (CVAAS)afterpressuredigestion ProduitsalimentairesDosagedeslmentstraces Dosagedumercureparspectromtriedabsorption atomiquepargnrationdevapeursfroidesaprsdigestion souspression

9、LebensmittelBestimmungvonElementspuren BestimmungvonQuecksilbermit Atomabsorptionsspektrometrie(AAS)Kaltdampftechnik nachDruckaufschluss ThisEuropeanStandardwasapprovedbyCENon29May2002. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an S

10、tandardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadeby

11、tra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,N

12、orway,Portugal,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2002CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN1

13、3806:2002EEN13806:2002(E) 2 Contents page Foreword3 1 Scope 3 2 Normativereferences 3 3 Principle3 4 Reagents.4 5 Apparatusandequipment. 5 6 Procedure .5 7 Calculation6 8 Limitofquantification . 6 9 Precision.7 10 Testreport 8 AnnexA (informative) Resultsoftheinterlaboratorytests .9 Bibliography 11E

14、N13806:2002(E) 3 Foreword ThisEuropeanStandardhasbeenpreparedbyTechnicalCommitteeCEN/TC275“FoodanalysisHorizontal methods“,thesecretariatofwhichisheldbyDIN. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationofanidenticaltextor byendorsement,atthelatestbyFebruary2003,and

15、conflictingnationalstandardsshallbewithdrawnatthelatest byFebruary2003. AnnexAisinformative. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowingcoun triesareboundtoimplementthisEuropeanStandard:Austria,Belgium,CzechRepublic,Denmark,Finland, France,Germany,Gre

16、ece,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain,Swe den,SwitzerlandandtheUnitedKingdom. 1Scope ThisEuropeanStandardspecifiesamethodforthedeterminationofmercuryinfoodstuffsbycoldvapouratomic absorptionspectrometry(CVAAS)afterpressuredigestion. SpecificfoodstuffsforwhichEu

17、ropeanStandardsexistareexcludedfromthescopeofthishorizontalEuropean Standard.Itisthetaskoftheanalysttoreviewifverticalstandardsexist. 2 Normativereferences ThisEuropeanStandardincorporatesbydatedorundatedreference,provisionsfromotherpublications.These normativereferencesarecitedattheappropriateplace

18、sinthetext,andthepublicationsarelistedhereafter.For datedreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsapplytothisEuropean Standardonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferencesthelatesteditionofthe publicationreferredtoapplies(includingamendments). EN13804,

19、FoodstuffsDeterminationoftraceelements Performancecriteria,generalconsiderationsand samplepreparation. EN13805, FoodstuffsDeterminationoftraceelementsPressuredigestion. 3Principle Determinationofmercuryinthetestsolutionbycoldvapouratomicabsorptionspectrometry(CVAAS)afterpressure digestionaccordingto

20、EN13805. Thetestsolutionistransferredtothereactionvesselofthemercuryanalysisunit,andthemercuryisreducedwith divalenttinorsodiumborohydrideandflushedintothecuvetteoftheAASinstrumentusingacarriergasstream. Theabsorptionat253,7nm(mercuryline)isusedasameasureofthemercuryconcentrationinthecuvette.Ifthe a

21、mountsofmercuryinthetestsolutionareverysmall,itisadvisabletoenrichthemercuryexpelledona gold/platinumgauze(amalgamtechnique)priortodeterminationinthecuvette.EN13806:2002(E) 4 WARNINGTheuseofthisstandardcaninvolvehazardousmaterials,operationsandequipment.This standarddoesnotpurporttoaddressallthesafe

22、typroblemsassociatedwithitsuse.Itistheresponsibility oftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplica bilityofregulatorylimitationspriortouse. 4Reagents 4.1General Theconcentrationofthetraceelementsinthereagentsandwaterusedshallbelowenoughnottoaffectthere s

23、ultsofthedetermination. 4.2Hydrochloricacid, notlessthan30%(massfraction),ofapproximately (HCl)=1,15g/ml. 4.3Nitricacid, notlessthan65%(massfraction),ofapproximately (HNO 3 )=1,4g/ml. 4.4Dilutednitricacid. Mixnitricacid(4.3)andwaterinaproportionof1+9partsbyvolumeasaminimum. 4.5Reducingagent 4.5.1Gen

24、eral Tin(II)chlorideorsodiumborohydridemaybeusedasthereducingagent,butitisnotadvisabletousethetwo reagentsalternately.Observetheinstructionsofthemanufacturersoftheapparatus. 4.5.2 Tin(II)chloridesolution withaconcentrationof100g/l. Dissolve50goftin(II)chloride,SnCl 2 2H 2 Oinapproximately100mlofhydr

25、ochloricacid(4.2)ina500mlvolu metricflaskanddilutetothemarkwithwater.Prepareafreshsolution. 4.5.3 Sodiumborohydridesolution withaconcentrationof30g/l. Dissolve3gofsodiumborohydridetogetherwith1gofsodiumhydroxidepelletsinwateranddiluteto100ml. Prepareafreshsolutiondailyand,whennecessary,filteritbefor

26、euse. Theconcentrationbymassofthereducingagentsolutionsmaybevariedtosuitthesystemandtherelevantinfor mationprovidedbythemanufactureroftheapparatusshallbeobserved. WARNINGItisessentialtoobservethe safetyinstructions for working with sodium borohydride. So diumborohydrideformshydrogenwithacidsandthisc

27、anresultinanexplosiveair/hydrogenmixture.A permanentextractionsystemshallbeprovidedatthepointwheremeasurementsarecarriedout. 4.6Potassiumpermanganatesolution withaconcentrationof40g/l. Dissolve0,4gofpotassiumpermanganatesolutioninwateranddiluteto10ml.Prepareafreshsolutiondaily. 4.7Potassiumdichromat

28、esolution withaconcentrationof5g/l. Dissolve5gofpotassiumdichromatein500mlofnitricacid(4.3)anddiluteto1lwithwater.EN13806:2002(E) 5 4.8Mercurystocksolution withamercuryconcentrationof1000mg/l. Dissolve1,080gofmercury(II)oxidein10mlofpotassiumdichromatesolution(4.7)anddiluteto1lwithwater. Thestocksol

29、utionisalsocommerciallyavailable.Itisadvisabletousecertifiedstocksolutions. 4.9Mercurycalibrationsolutions. Dilutethestocksolutionstotheconcentrationsneededforcalibration,with10mlofpotassiumdichromatesolution (4.7)perlitreineachsolution.Choosetheconcentrationssoasnottoexceedthelinearrangeofthecalibr

30、ation function.Itisrecommendedtouseaminimumof3calibrationsolutionswithdifferentconcentrations. Theconcentrationofacidinthecalibrationsolutionsshallbeequaltothatinthetestsolution.Mercurysolutionsare notstableforalongtime,evenatfairlyhighconcentrationsandshallthereforebemadeupdaily. 4.10 Zeromembercom

31、pensationsolution. Thezeromembercompensationsolutionshallcontainwater,10ml/lofpotassiumdichromate(4.7)andanamount ofnitricacid(4.3)whichisequaltotheacidconcentrationinthetestsolution. 5 Apparatusandequipment 5.1General Tominimisethecontamination,allapparatuswhichcomeintodirectcontactwiththesampleand

32、thesolutions shouldbecarefullypretreatedaccordingtoEN13804. 5.2Atomicabsorptionspectrometer, optionallywithbackgroundcorrection,andwiththeaccessoriesused forthecoldvapourandoptionallyamalgamtechniquesandwithameasurementandrecordingsystem.Asanal ternativetothemanualmethod,aflowinjectionsystemmaybeuse

33、d. 5.3Elementspecificlamp formercury. 6Procedure 6.1Coldvapouratomicabsorptionspectrometry(CVAAS) 6.1.1Spectrometer settings Todeviseatestschedule,firstadjusttheapparatusasspecifiedintheoperatingmanualofthemanufacturer,then optimisethesettings,payingparticularattentiontogasflowtimesandtheamountsofti

34、n(II)chlorideorsodium borohydrideintroduced. 6.1.2 ExampleofCVAASdetermination Adjustthezerooftheinstrumentusingthezeromembercompensationsolutiondescribedin4.10whennecessary. Usetheappropriatecalibrationsolutionstoobtainthecalibrationfunction.Ifpossible,calibratethemeasurement readingdirectlyinconce

35、ntrationusingthecalibrationsolutions.Checkthelinearrangeofthecalibrationfunction regularly. Afterthecalibrationfunctionhasbeenestablished,thetestsolutionmaybeusedforthedetermination,eitherwith outfurthertreatmentor,iftheconcentrationisoutsidethelinearrange,aftersuitabledilution.Whencarryingout prolo

36、ngedseriesofmeasurements,itisadvisabletocheckthezeroandthecalibrationatintervals.EN13806:2002(E) 6 Inordertoavoidabsorptionofmercuryonthewallsofthemeasuringvesselsandtoenhancestabilityofcalibration andsamplesolutionsduringlongruns,itmaybeadvisabletoaddafewdropsofpotassiumpermanganatesolution (4.6)to

37、thesamplesolutioninthemeasuringvesseluntiltheredcolorationispermanent.Allowthesolutionto standfortenminutesbeforeconnectingittothereactionunitforthedetermination. Althoughacorrectionisseldomnecessaryinthecaseofthecoldvapourtechnique,whetherthebackgroundcor rectionisnecessaryornotshallbecheckedforeve

38、rytypeofsample.Asananalyticalqualitycontrol,reference sampleshavingreliablyknownmercurycontentsshallbeanalysedinparallelwithalltheseriesofsamplesana lysed,thereferencesamplesbeingsubjectedtoallthestepsinthemethodstartingfromdigestion.Blanksolutions preparedbysubjectingthemtoallthestepsinthemethodsha

39、llalsobedetermined. 7Calculation Calculatethemassfractionofmercury, w,inmilligramsperkilogramofsample,usingthefollowingequation: 1000 1 = m V V a w (1) where a istheabsolutemassofmercury,innanogram,foundinthetestsolutionused; V isthevolumeofthedigestionsolutionafterbeingmadeup,inmillilitre; V 1 isth

40、evolumeoftestsolutionused,inmillilitre; m istheinitialsamplemass,ingram. Ifnecessary,subtracttheresultoftheblanksolutionfromthecontent, a,ofmercury. 8 Limitofquantification ThelimitofquantificationaccordingtoEN13804ofthemeasuringsolutiondependsonthefollowingparameters: principleofreleaseofmercury(ba

41、tchorflowsystem); enrichment(amalgam)ornoenrichment; inthecaseofflowsystems: continuous/discontinuousreleaseofHg; amountofdigestionsolutionused; constructionoftheequipment; influencesofthematrix. Thelimitofquantificationisregularlyintherangebetween0,05 Withatestportionof0,5gandafinaldigestionvolumeo

42、f20mlthelimitofquantificationforthefoodstuffwillbe calculatedbetween0,002mg/kgand0,2mg/kg.EN13806:2002(E) 7 9Precision 9.1General DetailsofaninterlaboratorytestontheprecisionofthemethodaresummarisedinannexA.Thevaluesderived fromthisinterlaboratorytestmaynotbeapplicabletoconcentrationrangesandmatrice

43、sotherthanthosegiven. 9.2Repeatability Theabsolutedifferencebetweentwoindependentsingletestresults,obtainedwiththesamemethodonidentical testmaterialinthesamelaboratorybythesameoperatorusingthesameequipmentwithinashortintervaloftime, willinnotmorethan5%ofthecasesexceedthevaluesof rgiveninTable1. Table1Repeatability Sample x mg/kg r mg/kg BovineLiver,lyophilised 0,042 0,007 SaltWaterFish,homogenised 0,36 0