1、BRITISH STANDARD BS EN 1788:2001 The European Standard EN 1788:2001 has the status of a British Standard ICS 67.050 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS EN 1788:2001 This British Standard, having been prepared under the direction of the Consumer Products and Servi
2、ces Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 3 December 2001 BSI 3 December 2001 ISBN 0 580 38328 8 National foreword This British Standard is the official English language version of EN 1788:2001. It supersedes BS EN 1
3、788:1997 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/-/3, Food analysis Horizontal methods, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The
4、 British Standards which implement international or European 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 Electronic Catalogue. A B
5、ritish 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. aid enquirers to understand the text; presen
6、t to the responsible 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 cover, an inside front cov
7、er, the EN title page, pages 2 to 18, an inside back cover 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 EN1788 October2001 ICS6
8、7.050 SupersedesEN1788:1996 Englishversion FoodstuffsThermoluminescencedetectionofirradiatedfood fromwhichsilicatemineralscanbeisolated ProduitsalimentairesDtectionparthermoluminescence dalimentsionissdontpeuventtreextraitsdesminraux silicats LebensmittelThermolumineszenzverfahrenzum Nachweisvonbest
9、rahltenLebensmitteln,vondenen Silikatmineralienisoliertwerdenknnen ThisEuropeanStandardwasapprovedbyCENon18August2001. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelis
10、tsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguagean
11、dnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Iceland,Ireland,Italy,Luxembourg,Netherlands,Norway,Portugal,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTE
12、EFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2001CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.EN1788:2001EEN1788:2001(E) 2 Contents Foreword2 1 Scope 3 2 Normativereferen
13、ces 3 3 Termsanddefinitions. .3 4 Principle4 5 Reagents.4 6 Apparatus .4 7 Samplingtechnique .5 8 Procedure .6 9 Evaluation.9 10 Limitations10 11 Validation10 12 Testreport 11 AnnexA (normative) Estimationofblanklevels. .12 AnnexB (informative) PracticalexamplefordefiningtemperatureintervalsoftheTLh
14、eatingunit .13 AnnexC (informative) ExamplesforTLglowcurvesusingvariousreaders14 Bibliography 16 Foreword ThisEuropeanStandardhasbeenpreparedbyTechnicalCommitteeCEN/TC275“FoodanalysisHorizontal methods“,thesecretariatofwhichisheldbyDIN. ThisEuropeanStandardreplacesEN1788:1996. ThisEuropeanStandardsh
15、allbegiventhestatusofanationalstandard,eitherbypublicationofanidenticaltextor byendorsement,atthelatestbyApril2002,andconflictingnationalstandardsshallbewithdrawnatthelatestby April2002. Thisdocumentwaselaboratedonthebasisofaprotocoldevelopedfollowingaconcertedactionsupportedbythe CommissionofEurope
16、anUnion(XIIC.5).ExpertsandlaboratoriesfromE.U.andEFTAcountries,contributed jointlytothedevelopmentofthisprotocol. ThispredecessorofthisdocumenthasbeenpreparedunderamandategiventoCENbytheCommissionofthe EuropeanCommunitiesandtheEuropeanFreeTradeAssociation. WARNING: Theuseofthisstandardmayinvolvehaza
17、rdousmaterials,operationsandequipment.Thisstandard doesnotpurporttoaddressallthesafetyproblemsassociatedwithitsuse.Itistheresponsibilityoftheuserofthis standardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatory limitationspriortouse. TheannexAisnormative;theannexe
18、sBandCareinformative. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEuropeanStandard:Austria,Belgium,CzechRepublic,Denmark,Finland, France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg,Netherlands,Norway,Portugal,Spain,
19、Sweden, SwitzerlandandtheUnitedKingdom.EN1788:2001(E) 3 1Scope ThisEuropeanStandardspecifiesamethodforthedetectionofirradiationtreatmentoffoodand/orfood ingredientsbythermoluminescenceanalysisofcontaminatingsilicateminerals.Thismethodisapplicabletothose foodstuffsfromwhichasufficientamountofsilicate
20、mineralscanbeisolated. Themethodhasbeensuccessfullytestedininterlaboratorytestswithherbsandspicesaswellastheirmixtures1 to3,shellfishincludingshrimpsandprawns4to6,bothfreshanddehydratedfruitsandvegetables7to9, andpotatoes10.Otherstudies11to46demonstratethatthemethodisapplicabletoalargevarietyof food
21、stuffs. 2 Normativereferences ThisEuropeanStandardincorporatesbydatedorundatedreference,provisionsfromotherpublications.These normativereferencesarecitedattheappropriateplacesinthetextandthepublicationsarelistedhereafter.For datedreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsap
22、plytothisEuropean Standardonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferencesthelatesteditionofthe publicationreferredtoapplies(includingamendments). ENISO3696, WaterforanalyticallaboratoryuseSpecificationandtestmethods(ISO3696). 3 Termsanddefinitions ForthepurposesofthisEuropeanStand
23、ard,thefollowingtermsanddefinitionsapply. 3.1 thermoluminescence(TL) lightemissionwhichoccursonheatingasolidmaterialinadditiontoblackbodyradiation,duetothethermally stimulatedreleaseoftrappedchargecarriers 3.2 TLintensity amountoflightdetectedperunittemperatureintervalatagivenheatingrate.Theintegrat
24、edTLintensityovera statedtemperatureintervalismeasuredinphotoncountsorcoulombs. 3.3 glowcurve variationofTLintensitywithtemperature.Theintegraloftheglowcurveisexpressedincountsorcoulombs dependingontheapparatusused. 3.4 Glow1 glowcurverecordedfromthemineralsofthepreparedsample 3.5 Glow2 glowcurverec
25、ordedfromthemineralsofthepreparedsampleaftermeasurementofGlow1andasubsequent exposuretoafixedknowndoseofradiationforthepurposeofnormalization 3.6 TLglowratio ratioofintegratedTLintensitiesofGlow1toGlow2,evaluatedoverastatedtemperatureinterval 3.7 MinimumDetectableintegratedTLintensityLevel(MDL) full
26、processblanklevel(Glow1)plusthreestandarddeviationsoverastatedtemperatureinterval(fullprocess blanklevelsshouldbemeasuredinparallelwithsampleextractionsusingportionsofthesamestocksolutionsand followingtheprocedureatallsteps)definestheMDL,whichshouldbeconsistentwithfreedomfromluminescent contaminatio
27、nofdiscs,glasswareandreagents(seeAnnexA)EN1788:2001(E) 4 3.8 backgroundoftheTLreader integratedTLintensitymeasuredwithoutsamplediscoverthewholetemperaturerangestudied 4Principle Silicatemineralscontaminatingfoodstuffsstoreenergybychargetrappingprocessesasaresultofexposureto ionizingradiation.Releasi
28、ngsuchenergy,bycontrolledheatingofisolatedsilicateminerals,givesriseto measurableTLglowcurves. Silicatemineralsarethereforeisolatedfromthefoodstuffs,mostlybyadensityseparationstep.Inordernotto obscuretheTL,theisolatedsilicatemineralsshouldbeasfreeoforganicconstituentsaspossible.Afirstglowof thesepar
29、atedmineralextractsisrecorded(Glow1).Sincevariousamountsand/ortypesofminerals(quartz, feldsparetc.)exhibitveryvariableintegratedTLintensitiesafterirradiation,asecondTLglow(Glow2)ofthesame sampleafterexposuretoafixeddoseofradiationisnecessarytonormalizetheTLresponse. TheTLglowratio,thusobtained,isuse
30、dtoindicateradiationtreatmentofthefood,sincethepopulationof irradiatedsamplesonprincipleyieldshigherTLglowratiosthanthatofunirradiatedsamples.Glowshape parametersofferadditionalevidenceforidentifyingirradiatedfoods.ThismethodofTLanalysisreliessolelyonthe silicatemineralswhichcanbeseparatedfromvariou
31、sfoodsandisnotprincipallyinfluencedbythekindoffood product. 5Reagents 5.1General Onlyusereagentsofrecognizedanalyticalgrade.Watershallbeofatleastgrade3inaccordancewith ENISO3696.Allreagentsshallbekeptfreefromparticulatecontaminationthroughouttheprocedure. 5.2SodiumpolytungstateNa 6 H 2 W 12 O 40 xH
32、2 O solutionwithadensityof2g/ml.Thesolutionmaybe recoveredandpurifiedforreuse2. 5.3Hydrochloricacid, substanceconcentration c(HCl)=1mol/land/or4mol/lto6mol/l(forspecial cases) 5.4Ammoniumhydroxidesolution, e.g. c(NH 4 OH)=1mol/l 5.5Acetone 5.6Nitrogengas, oxygenfree,forflushingtheTLheatingchamber 5.
33、7Siliconespray (optional) 5.8Ethanol 6Apparatus 6.1General Alllaboratorysurfacesandglasswareshouldbecarefullycleaned.Useusuallaboratoryapparatusand,in particular,thefollowing: 6.2TLreader withglowcurverecordingfacilityanddataevaluation;heatingrate:about6C/s;maximumtemperaturerequired: atleast350C;eq
34、uippedwithasuitablephotomultipliertube,e.g.abialkaliphotocathodephotomultipliertube,inEN1788:2001(E) 5 combinationwithfilterstorejectblackbodyradiation.AcceptablefiltercombinationsareCorning7/59+Schott KG1filtersorSchottBG39 1) ,orequivalent. 6.3Stainlesssteeldiscs orshallowcupshavingadiametertosuit
35、theTLreader(usuallyabout9mmupto10mm)andathicknessof0,25 mmupto0,5mm. 6.4Radiationsource capableofirradiatingdiscsorcupswithisolatedmineralsatadefinedradiationdosebeforemeasurementof Glow2.Intheinterlaboratorytestsonherbs,spicesandtheirmixtures1to3,shellfish4to6,freshand dehydratedfruitsandvegetables
36、7to9,varioussourcesdelivering 60 Coyrayshavebeenemployedatafixed radiationdoseof1kGy.Intheinterlaboratorytestonpotatoes10 60 Coyraysatafixeddoseofonly250Gyhave beenused. NOTE1Otherfixeddosescanbesuitable. NOTE2Alternativesto 60 Coyrayscanbeused,providedtheyhavebeenfoundsatisfactory. 6.5Ultrasonicbat
37、h capableoffittingseveralbeakersof150ml.Forlargersamplevolumes,e.g.withdehydratedfruitsandvegetables orlargerfruitsorpotatoes,anultrasonicbath,capableoffittingseveralbeakersof1000mlmaybeadvantageous. 6.6Nylondisposablesieves, comprisedofe.g.: 6.6.1 Minisieveset (e.g.diameter50mm),consistingoftworing
38、sbetweenwhichthenylonsieveclothis clamped. 6.6.2 Nylonsievecloth, withporesizesof125mand250m. 6.7Centrifuge suppliedwithaswingoutrotorandsuitableglasstubes,e.g.of10mlto15mlcapacitywithpointedbottom; providingacentrifugalaccelerationofabout1000 gattheouterendofthetubes. 6.8Vortexforcentrifugetubes (o
39、ptional) 6.9Vacuumpump (optional) 6.10Laboratoryoven, setto(505)C. 6.11Refluxapparatus 6.12Scalpelandforceps 7 Samplingtechnique Wheneverpossible,thesampleshouldbetakenfromalightprotectedpositioninthefoodconsignment,sincethe TLintensitydecreasesonexposuretolight. Beforeanalysis,samplesshouldbeprotec
40、tedagainstlightexposureandbestoredinthedark.Avoidexposureof samplestotemperaturesinexcessof100C,sinceheatingreducesTLintensity. 1) Corning7/59,SchottKG1andSchottBG39areexamplesofsuitableproductsavailablecommercially.This informationisgivenfortheconvenienceofusersofthisstandardanddoesnotconstituteane
41、ndorsementbyCENofthese products.EN1788:2001(E) 6 8Procedure 8.1General Severalproceduresformineralseparationmaybeused,e.g.handpicking,rinsingbywater,densityseparation and/orhydrolysis.Theproceduresformineralisolationdescribedin8.2havebeenfoundtobesatisfactory.Forany otherprocedure,ithastobeascertain
42、edthatthemineralisolationproceduredoesnotaffectthequalitative classification. Theisolatedsilicatemineralsshouldbefreeoforganicmaterial.Thepresenceoforganicmattercouldinduce spurious(nonradiationinduced)luminescence,orinextremecasescouldobscureTL.Sampleswithorganic residuesareblackenedbytheTLmeasurem
43、entprocess. Furthermore,duringisolationthemineralsshouldbeprotectedagainstlightexposure,i.e.notexposedtostrong lightorunnecessarilykeptexposedtolight,topreventopticalbleaching.Itmaybefavourabletousesubduedlight conditions.Someauthorsprefertoworkundersafelightconditions.However,theinterlaboratorytestswithherbs, spices,theirmixtures,shrimps1to5,freshanddehydratedfruitsandvegetables7,9andpotatoes10 demonstratethatprotectionfromstronglightunderusuallaboratoryconditionsmayprovesatisfactory. T
