EN 14082-2003 en Foodstuffs - Determination of trace elements - Determination of lead cadmium zinc copper iron and chromium by atomic absorption spectrometry (AAS) after dry ashing.pdf

1、BRITISH STANDARD BS EN 14082:2003 Foodstuffs Determination of trace elements Determination of lead, cadmium, zinc, copper, iron and chromium by atomic absorption spectrometry (AAS) after ash drying The European Standard EN 14082:2003 has the status of a British Standard ICS 67.050 BS EN 14082:2003 T

2、his British Standard was published under the authority of the Standards Policy and Strategy Committee on 2 April 2003 BSI 2 April 2003 ISBN 0 580 41523 6 National foreword This British Standard is the official English language version of EN 14082:2003. The UK participation in its preparation was ent

3、rusted 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 proposa

6、ls 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 17 and a back cover. The BSI copyright date displayed

7、 in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN14082 March2003 ICS67.050 Englishversion FoodstuffsDeterminationoftraceelementsDeterminationof lead,cadmium,zinc,copper,ironandchr

8、omiumbyatomic absorptionspectrometry(AAS)afterdryashing ProduitsalimentairesDosagedeslmentstraces Dterminationduplomb,cadmium,zinc,cuivre,feret chromeparspectromtriedabsorptionatomique(AAS) aprscalcinationsec LebensmittelBestimmungvonElementspuren BestimmungvonBlei,Cadmium,Zink,Kupfer,Eisenund Chrom

9、mitAtomabsorptionsspektrometrie(AAS)nach Trockenveraschung ThisEuropeanStandardwasapprovedbyCENon18December2002. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandb

10、ibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotif

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

12、m. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2003CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN14082:2003EEN14082:2003(E) 2 Contents page Foreword3 1

13、Scope 3 2 Normativereferences 3 3 Principle3 4 Reagents.4 5 Apparatusandequipment. 5 6 Procedure .5 7 Calculation8 8 Precision.9 9 Testreport . .10 AnnexA (informative) Resultsoftheinterlaboratorytest .11 Bibliography 17EN14082:2003(E) 3 Foreword Thisdocument(EN14082:2003)hasbeenpreparedbyTechnicalC

14、ommitteeCEN/TC275“Foodanalysis Horizontalmethods“,thesecretariatofwhichisheldbyDIN. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationofanidenticaltextor byendorsement,atthelatestbySeptember2003,andconflictingnationalstandardsshallbewithdrawnatthe latestbySeptember2003.

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

16、ortugal, Slovakia,Spain,Sweden,SwitzerlandandtheUnitedKingdom. 1Scope ThisEuropeanStandardspecifiesamethodforthedeterminationoflead,cadmium,zinc,copper,ironand chromiuminfoodstuffsbyatomicabsorptionspectrometry(AAS)afterdryashingat450C. Themethodisapplicabletodeterminationinvarioustypesoffoodstuffs.

17、Themethodhasbeensuccessfullytested inaninterlaboratorytrialinwhich16laboratoriesparticipated1.Foodstuffscoveredbythevalidationofthe methodincludecompositediets,cereals,fish,fruit,liverandmilk. SpecificfoodstuffsforwhichEuropeanStandardsexistareexcludedfromthescopeofthishorizontalEuropean Standard.It

18、isthetaskoftheanalysttoreviewifverticalstandardsexist. 2 Normativereferences ThisEuropeanStandardincorporatesbydatedorundatedreference,provisionsfromotherpublications.These normativereferencesarecitedattheappropriateplacesinthetext,andthepublicationsarelistedhereafter.For datedreferences,subsequenta

19、mendmentstoorrevisionsofanyofthesepublicationsapplytothisEuropean Standardonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferencesthelatesteditionofthe publicationreferredtoapplies(includingamendments). EN13804,FoodstuffsDeterminationoftraceelementsPerformancecriteria,generalconsiderations

20、and samplepreparation. 3Principle Thesamplesaredryashedat450Cunderagradualincreaseintemperature.Theashisdissolvedinhydrochloric acid,andthesolutionobtainedevaporatedtodryness.Thefinalresidueisredissolvedin c (0,1mol/l)nitricacid, andthemetalcontentsaredeterminedbyflameorgraphitefurnaceatomicabsorpti

21、onspectrometryprocedures. WARNINGTheuseofthisstandardcaninvolvehazardousmaterials,operationsandequipment.This standarddoesnotpurporttoaddressallthesafetyproblemsassociatedwithitsuse.Itistheresponsibility oftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminethe applicabili

22、tyofregulatorylimitationspriortouse.EN14082:2003(E) 4 4Reagents 4.1General Theconcentrationofthetraceelementsinthereagentsandwaterusedshallbelowenoughnottoaffectthe resultsofthedetermination. 4.2Hydrochloricacid, notlessthan37%massfraction,havingadensityofapproximately r (HCl)=1190mg/ml. 4.2.1Hydroc

23、hloricacid, c(6mol/l).Dilute500mlconcentratedhydrochloricacid(4.2)withwaterto1000ml. 4.3Nitricacid, notlessthan65%massfraction,havingadensityofapproximately r (HNO 3 )=1400mg/ml. 4.3.1Nitricacid, c(0,1mol/l).Dilute7mlconcentratednitricacid(4.3)withwaterto1000ml. 4.4Standardsolutions NOTE Thestandard

24、solutionsforPb,Cd,Zn,CuandFecanbepreparedfrommetalsormetalsalts.Standardsolutions canalsobecommerciallyavailable.Itisadvisabletousecertifiedstandardsolutions.Thefollowingpreparationofstandard solutionsaregivenasanexample. 4.4.1 Leadstandardsolution. 1000mg/l.Dissolve1000mgPbin7mlnitricacid(4.3)in1lv

25、olumetricflask. Dilutetovolumewithwater. 4.4.2 Cadmiumstandardsolution. 1000mg/l.Dissolve1000mgCdin14mlwater+7mlnitricacid(4.3)in 1lvolumetricflask.Dilutetovolumewithwater. 4.4.3 Chromiumstandardsolution. 1000mg/l.Dissolve3735mgK 2 CrO 4 in7mlnitricacid(4.3)in 1lvolumetricflask.Dilutetovolumewithwat

26、er. 4.4.4 Zincstandardsolution. 1000mg/l.Dissolve1000mgZnin14mlwater+7mlnitricacid(4.3)in 1lvolumetricflask.Dilutetovolumewithwater. 4.4.5 Copperstandardsolution. 1000mg/l.Dissolve1000mgCuin7mlnitricacid(4.3)in1lvolumetric flask.Dilutetovolumewithwater. 4.4.6 Ironstandardsolution. 1000mg/l.Dissolve1

27、000mgFein14mlwater+7mlnitricacid(4.3)in 1lvolumetricflask.Dilutetovolumewithwater. 4.5Calibrationsolutions 4.5.1 Forgraphitefurnaceanalysis Dilutestandardsolutions4.4.1to4.4.3with c(0,1mol/l)nitricacid(4.3.1)toarangeofstandardsthatcoversthe linearrangeoftheelementtobedetermined. 4.5.2 Workingstandar

28、dsolutionsforflameanalysis Dilutestandardsolutions4.4.4to4.4.6with c(0,1mol/l)nitricacid(4.3.1)toarangeofstandardsthatcoversthe concentrationoftheelementtobedetermined.EN14082:2003(E) 5 5 Apparatusandequipment 5.1General Allglasswareandplasticwareshouldbecarefullycleanedandrinsedaccordingtotheproced

29、ureinEN13804. 5.2Atomicabsorptionspectrometer, withbackgroundcorrection,suppliedwithagraphite furnace/autosampler,burnersforflameanalysisandanappropriategassupply. 5.3Elementspecificlamps, e.g.hollowcathodelamps,forallelementsanalysed. 5.4Furnace, programmablewiththermostatcapableofmaintaining(450 2

30、5)C.Ifanonprogrammablefurnace isused,aseparatepreashingdeviceisrequired(see5.5to5.9). 5.5Hotplate, withstepwiseheatingcontrol,uptoabout300C. 5.6Lamp, IR250W,fixedtoaretortstandinawaythatallowsadjustmentofthedistancetotheplate. 5.7Ceramicplate, e.g.dessicatorplateonalowstand,withadiameterthatsuitsthe

31、hotplate. 5.8Glasscover, e.g.crystallisingdish,diameter185mm,height100mm. 5.9Washbottle containingsulphuricacidforpurificationofair. 5.10 Platinumorquartzcrucibles, 50mlto75ml. Specialattentionshouldbepaidtothecrucibles.Quartzcruciblesshallbestoredinamixtureofconcentratednitric acidandwater(1+9parts

32、byvolume)thenrinsedwithdeionisedwaterbeforeuse.Whennecessary,these crucibleshavetobeboiledwithacidaswellbeforeuse.Platinumcruciblesshouldpreferablybeheateduntilred hotandthereafterboiledwithacidpriortouse. 5.11 Plasticbottles, withleakproofclosures,100ml. 6Procedure 6.1Pretreatment Homogenisethesamp

33、leinaccordancewiththerecommendationsinEN13804. 6.2Dryashing Weighaconvenientamountofsample(10gto20gingeneral)intoacrucible,tothenearest10mg,dependingon thekindofsample.Proceedaccordingtotypeoffurnace. NOTE Calcinationsaidcanbeused,andvalidated,bytheindividuallaboratory. 6.2.1 Dryingandashinginaprogr

34、ammablefurnace: Placethecruciblewiththetestportioninthefurnaceat aninitialtemperaturenothigherthan100C.Increasethetemperatureatamaximumrateof50C/hto450C. Letthesamplestandovernight.Ifthereisariskofheavyboilingmakesurethatthedryingtemperature/timeis sufficientlylow/long.Continueaccordingto6.2.3.EN140

35、82:2003(E) 6 6.2.2 Dryingandashinginanonprogrammablefurnace withthermostatandanassemblyfordrying/pre ashing(hotplatewithceramicplateandglasscover+IRlamp+washbottlewithsulphuricacidforpurificationof air):SeeFigure1. NOTE Aprogrammablefurnaceispreferable. Key 1Infraredlamp 2Air 3Crystallisingdish 4Cer

36、amicplate 5Hotplate Figure1Apparatusforpreashingofsamples Placethecruciblewiththetestportioncoveredwiththeglasscoverontheceramicplate,andletpurifiedaircoming throughaglasstubesweepoverthesample.PuttheIRlampatadistanceof30cmto40cmfromthesampleand setthehotplateatabout100C.Reducethedistanceasthedrying

37、proceedsuntilthesamplecanbeassumedto bedry.Thelampshouldthenberightdownatthecover. PreashthesamplebyincreasingthetemperatureslowlyandstepwisewithanIRlampandahotplate.Thefinal temperatureontheceramicplateshouldthenbeabout300C.Thetimerequiredforthepreashingvariesstrongly dependingonthetypeofsample. Pu

38、tthecrucibleinthefurnaceat200Cto250Candslowlyraisethetemperatureto450Catarateofnotmore than50C/h.Letthesamplestandovernight.EN14082:2003(E) 7 6.2.3 Dissolutionofthesampleash Takethecrucibleoutofthefurnaceandletitcool.Wettheashwith1mlto3mlwater,andevaporateitonawater bathorhotplate.Putthecrucibleback

39、inthefurnaceatnomorethan200Candraisethetemperaturestepwise to450C.Proceedwiththeashingat450Cfor1hto2horlonger.Repeatthisprocedureuntilthesampleis completelycombusted,i.e.theashshouldbewhite/greyorslightlycoloured(thenumberofrepetitionsnecessary variesstronglydependingonthetypeofsample).Add5mlhydroch

40、loricacid(4.2.1)tothecrucible,ensuringthat alltheashcomesintocontactwiththeacid.Evaporatetheacidonawaterbathorhotplate.Dissolvetheresiduein anexactvolume(10,0mlto30,0ml)ofnitricacid(4.3.1).Swirlthecruciblewithcaresothatalltheashcomesinto contactwiththeacid.Coverwithawatchglassandletthesamplestandfor

41、1hto2h.Thenstirthesolutioninthe cruciblethoroughlywithastirringrodandtransferthecontentstoaplasticbottle. CAUTIONSampleswithaveryhighfatand/orsugarcontentshouldbeashedwithgreatcare.Fatty samplescanotherwiseeasilyselfignite.Sugarrichsamplestendtoexpandduringtheashingandcanbe lost.Thepreashingprocedur

42、eaccordingto6.2.2isthenrecommended. Treatreagentblanksinthesamewayassamples. 6.3Atomicabsorptionspectrometry(AAS) 6.3.1General Themethodtobeusedflameorgraphitefurnacetechniqueisdeterminedbytheconcentrationoftheelementto beanalysed.FlameAASshouldbeusedwheneverpossible,sincethistechniqueislesssensitiv

43、etointerference thangraphitefurnaceAAS.DeterminationofPb,CdandCrinfoodstuffsgenerallyrequiregraphitefurnaceAAS. Zn,CuandFecaninmostfoodstuffsbedeterminedbyflameAAS.Examplesofwavelengths,gas mixtures/temperatureprogrammesandotherinstrumentalparametersappropriateforeachelementarefoundin themanualprovidedwiththeinstrument.Backgr