BS EN 14084-2003 Foodstuffs - Determination of trace elements - Determination of lead cadmium zinc copper and iron by atomic absorption spectrometry (AAS) after microwave digestion.pdf

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1、BRITISH STANDARD BS EN 14084:2003 Foodstuffs Determination of trace elements Determination of lead, cadmium, zinc, copper and iron by atomic absorption spectrometry (AAS) after microwave digestion The European Standard EN 14084:2003 has the status of a British Standard ICS 67.050 BS EN 14084:2003 Th

2、is British Standard was published under the authority of the Standards Policy and Strategy Committee on 24 April 2003 BSI 24 April 2003 ISBN 0 580 41656 9 National foreword This British Standard is the official English language version of EN 14084:2003. The UK participation in its preparation was en

3、trusted 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. Cross-references The British Standards which implement international or European publications referred to in

4、 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 or of British Standards Online. This publication does not purport to include all the necessary provisions of a

5、 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 text; present to the responsible international/European committee any enquiries on the interpretation, or propos

6、als 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 cover, an inside front cover, the EN title page, pages 2 to 16, an inside back cover and a back cover. The BSI c

7、opyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN14084 April2003 ICS67.050 Englishversion FoodstuffsDeterminationoftraceelementsDeterminationof lead,cadmium

8、,zinc,copperandironbyatomicabsorption spectrometry(AAS)aftermicrowavedigestion ProduitsalimentairesDosagedeslmentstraces Dosageduplomb,ducadmium,duzinc,ducuivreetdufer parspectromtriedabsorptionatomique(AAS)aprs digestionparmicroondes LebensmittelBestimmungvonElementspuren BestimmungvonBlei,Cadmium,

9、Zink,KupferundEisen mitAtomabsorptionsspektrometrie(AAS)nach Mikrowellenaufschluss ThisEuropeanStandardwasapprovedbyCENon18December2002. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalte

10、ration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberin

11、toitsownlanguageandnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Hungary,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Slovakia,Spain,Sweden,Swit

12、zerlandandUn ited Kingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2003CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN14084:2003EEN14084:2003(E) 2 Co

13、ntents page Foreword3 1 Scope 3 2 Normativereferences 3 3 Principle3 4 Reagents.4 5 Apparatusandequipment. 5 6 Procedure .5 7 Calculation8 8 Precision.8 9 Testreport . .9 AnnexA (informative) Resultsoftheinterlaboratorytest .10 Bibliography 16EN14084:2003(E) 3 Foreword Thisdocument(EN14084:2003)hasb

14、eenpreparedbyTechnicalCommitteeCEN/TC275“Foodanalysis Horizontalmethods“,thesecretariatofwhichisheldbyDIN. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationofanidenticaltextor byendorsement,atthelatestbyOctober2003,andconflictingnationalstandardsshallbewithdrawnatthela

15、test byOctober2003. AnnexAisinformative. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEuropeanStandard:Austria,Belgium,CzechRepublic,Denmark,Finland, France,Germany,Greece,Hungary,Iceland,Ireland,Italy,Luxembourg,Malta,N

16、etherlands,Norway,Portugal, Slovakia,Spain,Sweden,SwitzerlandandtheUnitedKingdom. 1Scope ThisEuropeanStandardspecifiesamethodforthedeterminationoflead,cadmium,zinc,copperandironin foodstuffsbyatomicabsorptionspectrometry(AAS)aftermicrowavedigestion. Themethodisapplicabletodeterminationinvarioustypes

17、offoodstuffs.Themethodisnotapplicabletooils,fats andotherextremelyfattyproducts. Themethodhasbeensuccessfullytestedinaninterlaboratorytrialinwhich16 laboratoriesparticipated1. Foodstuffscoveredbythevalidationofthemethodincludecompositediets,cereals,fish,beef,milkandfungi. SpecificfoodstuffsforwhichE

18、uropeanStandardsexistareexcludedfromthescopeofthishorizontalEuropean Standard.Itisthetaskoftheanalysttoreviewifverticalstandardsexist. 2 Normativereferences ThisEuropeanStandardincorporatesbydatedorundatedreference,provisionsfromotherpublications.These normativereferencesarecitedattheappropriateplac

19、esinthetext,andthepublicationsarelistedhereafter.For datedreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsapplytothisEuropean Standardonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferencesthelatesteditionofthe publicationsreferredtoapplies(includingamendments). EN1380

20、4, FoodstuffsDeterminationoftraceelementsPerformancecriteria,generalconsiderationsandsample preparation. 3Principle Thesamplesaredigestedinclosedvesselsinamicrowaveoveninamixtureofnitricacidandhydrogenperoxide. Theresultingsolutionisdilutedwithwater,andthemetalcontentsaredeterminedbyflameorgraphitef

21、urnace atomicabsorptionspectrometryprocedures. WARNINGTheuseofthisstandardcaninvolvehazardousmaterials,operationsandequipment.This standarddoesnotpurporttoaddressallthesafetyproblemsassociatedwithitsuse.Itistheresponsibility oftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddet

22、erminethe applicabilityofregulatorylimitationspriortouse.EN14084:2003(E) 4 4Reagents 4.1General Theconcentrationofthetraceelementsinthereagentsandwaterusedshallbelowenoughnottoaffectthe resultsofthedetermination. 4.2 Nitricacid, notlessthan65%,(massfraction),havingadensityofapproximately r (HNO 3 )=

23、1,4g/ml. 4.2.1 Nitricacid, c 0,1mol/l: Dilute7mlconcentratednitricacid(4.2)withwaterto1000ml. 4.2.2 Nitricacid, c 3mol/l: Dilute200mlofconcentratednitricacid(4.2)withwaterto1000ml. 4.3Hydrogen peroxide, 30%(massfraction). 4.4 Standardsolutions NOTE ThestandardsolutionsforPb,Cd,Zn,CuandFecanbeprepare

24、dfrommetalsormetalsalts.Standardsolutions canalsobecommerciallyavailable.Itisadvisabletousecertifiedstandardsolutions.Thefollowingpreparationofstandard solutionsaregivenasanexample. 4.4.1 Leadstandardsolution, 1000mg/l: Dissolve1,000gPbin7mlnitricacid(4.2)ina1000mlvolumetricflask.Dilutetovolumewithw

25、ater. 4.4.2 Cadmiumstandardsolution, 1000mg/l: Dissolve1,000gCdin20mlofamixtureof10mlwaterand10mlnitricacid(4.2)ina1000mlvolumetricflask. Dilutetovolumewithwater. 4.4.3 Zincstandardsolution, 1000mg/l: Dissolve1,000gZnin14mlofwaterand7mlnitricacid(4.2)ina1000mlvolumetricflask.Dilutetovolumewith water

26、. 4.4.4 Copperstandardsolution, 1000mg/l: Dissolve1,000gCuin7mlnitricacid(4.2)ina1000mlvolumetricflask.Dilutetovolumewithwater. 4.4.5 Ironstandardsolution, 1000mg/l: Dissolve1,000gFein14mlofwaterand7mlnitricacid(4.2)ina1000mlvolumetricflask.Dilutetovolumewith water. 4.5 Calibrationsolutions Dilutest

27、andardsolutions4.4.1to4.4.5with c 0,1mol/lnitricacid(4.2.1)toarangeofstandardsthatcoversthe linearrangeoftheelementtobedetermined.EN14084:2003(E) 5 5 Apparatusandequipment 5.1General AllglasswareandplasticwareshouldbecarefullycleanedandrinsedaccordingtotheprocedureinEN13804. 5.2 Atomicabsorptionspec

28、trometer, withbackgroundcorrection,suppliedwithagraphite furnace/autosampler,burnersforflameanalysisandanappropriategassupply. 5.3 Elementspecificlamps, e.g.hollowcathodelamps,forallelementsanalysed. 5.4 Graphitetubes, pyrolyticallycoatedandwithplatformsforPbandCd. 5.5Microwave oven, designedforlabo

29、ratoryuse(checkfordeliveredpoweraccordingtotheprocedurein EN13804)anddigestionvesselswithacapacityoftypically100mlandwithstandingapressureofatleast 1,4MPa. 5.6 Plasticbottles, withleakproofclosures,100ml. 6Procedure 6.1Pretreatment HomogenisethesampleinaccordancewiththerecommendationsinEN13804. Ifne

30、cessary,drythesampleina waythatdoesnotaffecttheelementcontent,e.g.byfreezedrying. 6.2Pressure digestion Weighanamountofsampleequivalentto0,2 gto0,5 gdrymatterintothedigestionvessel(5.5)oras recommendedbythemanufacturerofthemicrowavedigestionovenused.Themaximumtestportionfroma samplehavingawaterconte

31、ntofe.g.50%isthus1g(=0,5gdrymatter);foramaterialcontaining95%waterthe testportionmaybe2g(0,5gdrymatter).Includeonereagentblankineverybatch. Addtothedigestionvesseltypically5mlnitricacid(4.2)and2mlhydrogenperoxide(4.3)orasrecommendedby themanufacturerofthemicrowaveovenused.Sealthevesselandplaceitinit

32、sholderinthemicrowaveovenand closethedoor.Settheovenprogramme(poweragainsttime)asrecommendedbythemanufacturerforthe weighedtypeofsample. Typicallyanovenprogrammeincludesastageatlowpowerforafewminutesfollowedbyoneormorestagesat higherpowersettings.Agradualincreasebetweentheselectedstagesisrecommended

33、inordertopreventsudden pressurepeakstooccurinsidethepressurevessels.AnexampleofaprogrammehasbeenshowninTable1.EN14084:2003(E) 6 Table1Pressuredigestionprogramme (TheparametersaregivenasanexampleapplicabletoaCEMMDS2000oven 1 ) Step Power,W Time,min 1 250 3:00 2 630 5:00 3 500 22:00 4 0 15:00 Theprogr

34、ammeusedshouldbevalidontheconditionthatthefullnumberofpressurevesselsistreated simultaneously.Iffewervesselsaredigested,theremainingvesselsmaybetreatedasblanks.Iftheovenused includespressurecontrolinonlyonepressurevessel,thatvesselwiththeexpectedhighestpressureshouldbe monitored.Thisisgenerallytheve

35、sselwiththehighestsampleintakecalculatedasthedrymatter. Whendigestingunknownsamples,observecautionsinceatoolargeamountofsamplemayrupturethesafety membraneofthedigestionvessel.Inparticular,sampleshighincarbon(especiallysugar,fatand/orethanol)may causesuddenpressurepeaksduringtheashingprocess.Inallcas

36、es,thesampleintakeshouldbeinstrict compliancewiththemanufacturersrecommendations. 6.3Dilution Removethedigestionvesselsfromthemicrowaveovenandallowtocoolthoroughlybeforeattemptingtoopen them.Openthevesselandrinsedownthelidandthewallswithwaterintothecontainer.Makeuptoadefinite volume,atleast25ml,with

37、waterintoaplasticbottle(5.6).Treattheblankinthesameway. 6.4AAS 6.4.1General Themethodtobeusedflameorgraphitefurnacetechniqueisdeterminedbytheconcentrationofthemetalto beanalysed.PbandCdinfoodstuffsgenerallyrequiregraphitefurnaceAAS.Zn,CuandFecanusuallybe analysedbyflameAAS.Examplesofwavelength,gasmi

38、xture/temperatureprogrammesandotherinstrumental parametersappropriateforeachmetalarefoundinmanualsprovidedwiththeinstrument.Backgroundcorrection shouldalwaysbeused,unlessproventobeunnecessary. Itisimportantthatthemeasurementsaremadeinthelinearrangewhenthemethodofstandardadditionisused.A standardaddi

39、tioncurveshouldconsistofatleastthreepointsofwhichatleasttwoarestandardadditions.The concentrationofthehigheststandardshouldbe3to5timestheconcentrationinthesamplesolution.Theconcen trationofthelowerstandardshouldbehalfofthehigheststandard. 6.4.2 FlameAAStechnique Dilutethesamplesolution1+1with c 0,1m

40、ol/lnitricacid(4.2.1).Dilutestandardsolutions1+1with c 3mol/l nitricacid(4.2.2).Allfurtherdilutionsshouldbemadewith c 0,1 mol/lnitricacid(4.2.1).Thehighacid concentrationofthesamplesolutionafterdigestionhasdetrimentaleffectsonbothresultsandtheinstrument.Itis, therefore,importantthatthesolutionisdilu

41、tedasmuchaspossibleandthatstandardandsamplesolutionhavethe sameacidconcentration.WhenthisisdoneZnandCucan,asarule,bedeterminedagainstatraditionalstandard curve. 1 CEMMDS2000isatradenameofaproductsuppliedbyCEN,P.O.Box200,Matthews,NC28106200USA.This informationisgivenfortheconvenienceoftheusersofthisE

42、uropeanStandardanddoesnotconstituteanendorsementby CENoftheproductnamed.EN14084:2003(E) 7 ThedeterminationofFecanbestronglyaffectedbyinterferencesfromthematrix.Thereforeuseeitherthemethod ofstandardadditionormatrixmatchedstandardcurve.Whenexperiencingsevereinterferences,theuseofan oxidisingnitrousox

43、ideflamemaybeanalternative.Table2containsexamplesofinstrumentalparametersfor flametechniqueAAS. Table2InstrumentalparametersforflameAAS Metal Flame Wavelength, nm Zn Cu Fe Airacetylene,oxidising “ “ 213,9 324,7 248,3 6.4.3 Graphitefurnacetechnique ThistechniqueisgenerallyrequiredfordeterminationofPbandCd.Usepyrolyticallycoatedtubeswithplatforms. Sincemicrowav