BS 4325-14-2000 Methods for analysis of oilseed residues - Simultaneous determination of oil and water contents - Method using pulsed nuclear magnetic resonance spectroscopy《油料种子残留.pdf

1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 4325-14:2000 ISO 10632

2、:2000 ICS 67.200.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Methods for analysis of oilseed residues Part 14: Simultaneous determination of oil and water contents Method using pulsed nuclear magnetic resonance spectroscopyThis British Standard, having been prepared und

3、er the direction of the Consumer Products and Services Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 September 2000 BSI 09-2000 ISBN 0 580 36260 4 BS 4325-14:2000 Amendments issued since publication Amd. No. Date Comments National foreword

4、 This British Standard reproduces verbatim ISO 10632:2000 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee AW/2, Oilseeds and residues, which has the responsibility to: aid enquirers to understand the text; present to the res

5、ponsible 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. A list of organizations represented on this committee can be obtained on

6、request to its secretary. Cross-references The 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

7、of the BSI Standards Electronic Catalogue. A British 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

8、. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 9 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued.Referencenumber ISO10632:2000(E) INTERNATIONAL STANDARD

9、ISO 10632 Firstedition 2000-06-01 OilseedresiduesSimultaneous determinationofoilandwatercontents Methodusingpulsednuclearmagnetic resonancespectroscopy Tourteaux de graines olagineuses Dtermination simultane de la teneur en huile et en eau Mthode par rsonance magntique nuclaire pulse BS 4325-14:2000

10、ii BS 4325-14:2000 iii Foreword ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISO memberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnical committees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitte

11、ehasbeenestablishedhas therighttoberepresentedonthatcommittee.Internationalorganizations,governmentalandnon-governmental,in liaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnical Commission(IEC)onallmattersofelectrotechnicalstandardization. InternationalStand

12、ardsaredraftedinaccordancewiththerulesgivenintheISO/IECDirectives,Part3. DraftInternationalStandardsadoptedbythetechnicalcommitteesarecirculatedtothememberbodiesforvoting. PublicationasanInternationalStandardrequiresapprovalbyatleast75%ofthememberbodiescastingavote. Attentionisdrawntothepossibilityt

13、hatsomeoftheelementsofthisInternationalStandardmaybethesubjectof patentrights.ISOshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights. InternationalStandardISO10632waspreparedbyTechnicalCommitteeISO/TC34, Agricultural food products, SubcommitteeSC2, Oleaginous seeds and fruits. AnnexAofth

14、isInternationalStandardisforinformationonly. BS 4325-14:2000iv Introduction ThemethodspecifiedinthisInternationalStandardhasbeensubjectedtoaninternationalringtest.However,no precisiondatahavebeencalculatedbecauseofaninsufficientnumberofparticipatinglaboratories.Seeclause11 andannexA. BS 4325-14:2000

15、 1 OilseedresiduesSimultaneousdeterminationofoilandwater contentsMethodusingpulsednuclearmagneticresonance spectroscopy 1 Scope ThisInternationalStandardspecifiesarapidmethodusingnuclearmagneticresonance(NMR)forthe determinationoftheoilandwatercontentsofoilseedresiduesobtainedafteroilextractionbypre

16、ssureorsolvents (excludingmixedproducts). Itisapplicabletooilseedresiduesasflour,platesoragglomerates,providedthattheparticlesaresmallerthan 2mmandthatthewatercontentisnothigherthantheconversionthreshold. 2 Normativereferences Thefollowingnormativedocumentscontainprovisionswhich,throughreferenceinth

17、istext,constituteprovisionsof thisInternationalStandard.Fordatedreferences,subsequentamendmentsto,orrevisionsof,anyofthese publicationsdonotapply.However,partiestoagreementsbasedonthisInternationalStandardareencouragedto investigatethepossibilityofapplyingthemostrecenteditionsofthenormativedocuments

18、indicatedbelow.For undatedreferences,thelatesteditionofthenormativedocumentreferredtoapplies.MembersofISOandIEC maintainregistersofcurrentlyvalidInternationalStandards. ISO734-1, Oilseed residues Determination of oil content Part 1: Extraction method with hexane (or light petroleum). ISO734-2, Oilse

19、ed residues Determination of oil content Part 2: Rapid extraction method. ISO771, Oilseed residues Determination of moisture and volatile matter content. ISO5502, Oilseed residues Preparation of test samples. 3Principle ThetestsampleisplacedinthemagneticfieldofapulsedNMRspectrometer.Analternatingele

20、ctromagneticfield isappliedintheformofanintense90radiofrequency(RF)pulsewhichexcitesallthehydrogennuclei.Thefree inductiondecay(FID)isrecordedfollowingthe90pulse.Themaximumamplitudeofthissignalisproportionalto thetotalnumberofprotonsfromthewaterandoilphasesofthesample. AsecondRFpulse,aso-called180pu

21、lse,isthenappliedtoproduceaspin-echosignalwhenonlythesignalfrom theoilphasecontributestotheFID. NOTE1 Themaximumamplitudeofthisechosignalisproportionaltotheoilcontent.Itvarieswiththesampletemperature followingacomplexlaw.Anincreaseintemperaturedecreasesthemeasuredvalueoftheecho. Thedifferencebetween

22、thetwoamplitudes,whichisproportionaltothewatercontent,iscalculated. BS 4325-14:20002 Aftersuitablecalibrationoftheapparatus,themeasuredsignalsareautomaticallyconvertedintopercentagesofoil orwater. NOTE2 Simultaneousindicationsoftheoilandwatercontentscanbegivenbysomespectrometersequippedwitha minicom

23、puterandspecificprogram. 4 Calibrationsamples 4.1 General Calibrationsamplesshallbehomogeneousandfreefromimpurities. 4.2 Samplesformoisture-contentcalibration Thewatercontentofoilseedresiduescanvarydependingonstorageconditions.Itisthereforenecessaryto determinethisjustpriortocalibrationinaccordancew

24、ithISO771. 4.3 Samplesforoil-contentcalibration Samplesfromoilseedresiduesshallbeofthesamespeciesasthetestsamplesandofsimilarfattyacid compositions(especiallyfortheanalysisofrapeseedswhicharerichinerucicacid,andforsunflowerseedswhich arerichinoleicacid).Oilcontentshallbedeterminedusingthereferenceme

25、thoddescribedinISO734-1. 5 Apparatus Usuallaboratoryapparatusand,inparticular,thefollowing. 5.1 Pulsedlow-resolutionNMRspectrometer,suitableformeasurementoftheoilcontentandwatercontent ofoilseeds. Theinstrumentsparametersshallfollowthemanufacturersinstructionsorspecifications. CAUTION: Removemetalli

26、cobjectsfromtheproximityoftheNMRspectrometer. 5.2 Sampletubes,madeofglass,suitableforusewiththeNMRspectrometer. 5.3 Analyticalbalance,electronic,capableofweighingtoanaccuracyof0,01g,bypreferencelinkedtothe NMRspectrometersothatthesamplemassisrecordeddirectly. 5.4 Dryingoven,capableofbeingmaintaineda

27、t103C 2C. 5.5 Dishes,madeofglassormetal,ofdiameter7cm,andprovidedwithlids. 5.6 Desiccator,equippedwithanefficientdesiccant. 5.7 Mechanicalgrindingmillormortar,easytoclean,andcapableofgrindingtheplatesoragglomeratesof oilseedresiduestoparticlessmallerthan2mm,withoutheatingandwithoutperceptiblemodific

28、ationsinwater, volatilematterandoilcontents. BS 4325-14:2000 3 6 Sampling Itisimportantthatthelaboratoryreceiveasamplewhichistrulyrepresentativeandhasnotbeendamagedor changedduringtransportorstorage. SamplingisnotpartofthemethodspecifiedinthisInternationalStandard.Arecommendedsamplingmethodis giveni

29、nISO5500. 7 Preparationoftestsample PreparethetestsampleinaccordancewithISO5502. Removefromthepreparedtestsampleallmetallicobjects(e.g.staples,needles,etc.). 8 Calibrationprocedure 8.1 Generalprocedure 8.1.1 Inmanyoilseedresidues,theoilcontentislow(1%to3%)comparedtothewatercontent(8%to12%). Theavail

30、ablerangeofproductshasaverysmalloilorwatercontentlower,usuallylowerthan2%.Inthiscase, procedureBistobepreferred,carriedoutontwosamplestogivesixpointsonthecalibrationcurve.Whenthe watercontentishigherthantheoilcontent,theNMRsignalS 1 ,measuredafter50s,isverystrongcomparedto thespin-echosignalS 2 ofth

31、eoil.So,forthecalibrationandmeasurementoftheoilcontent,itisrecommendedto usethevalue(indecibels)oftheNMRsignalamplificationofthespectrometeroptimizedforthehighestsignal, whichwillbeconsequentlylesseffectiveforthelowestsignal. 8.1.2 Usetheset-upparametersoftheNMRspectrometer(5.1)recommendedbythemanuf

32、acturerandoptimize thembypreliminarytests.Forallcalibrationandmeasurementoperations,followtheusersmanual.Paystrict attentionthatalloperationsduringcalibrationandmeasurementarecarriedoutunderthesameconditionsand,in particular,atthesametemperature( 2C). Aminimumofthreecalibrationsamplesisnecessary,alt

33、houghmorethanthreesamplesmaybeused. 8.1.3 Entertheparametersforthemeasurements(pulsesequence,attenuation,etc.)oftheoilorwatercontent (asapplicable)intotheNMRspectrometerfollowingthemanufacturersrecommendations,andspecifyacode numberunderwhichthecalibrationcurveistobestored.Thetotalmeasurementtimesha

34、llbeaminimumof25s. 8.1.4 Settheapparatustothecalibrationmode. 8.1.5 Introduceaportionofthefirstcalibrationsampleintoataredsampletube(5.2),uptotheoptimumheight specifiedbythemanufacturer,andtransferthevalueofthesamplemassfromthebalancetotheNMR spectrometer. NOTE Manualtransferofthemassofthecalibratio

35、nsampletotheNMRspectrometerisalsopossible. 8.1.6 Enter,asapplicable,thevalueofeitherthewatercontent(asapercentagebymass)ortheoilcontentinto thespectrometer. 8.1.7 Introducethesampletubecontainingthefirstcalibrationsampleintothemeasuringheadanddetermine thewateroroilcontent. 8.1.8 Repeatsteps8.1.5to8

36、.1.7forthetwo(ormore)othercalibrationsamples. 8.1.9 Calculateautomaticallyormanuallythecalibrationparametersofthecalibrationcurve. BS 4325-14:20004 Thecorrelationcoefficientshallnormallybegreaterthan0,95.Ifthisinnotthecase,checkthevaluesobtained usingthereferencemethodsspecifiedinISO734andISO771,res

37、pectively,orrepeatthecalibrationprocedure usingthree(ormore)othercalibrationsamples. Storethecalibrationcurveunderthecodenumberchoseninstep8.1.3. 8.1.10Completetheoil-contentcalibrationcurvebyusinganemptytubeandbyrepeatingsteps8.1.5to8.1.7. Thispartofthemethodisnotapplicabletothewatercontentcalibrat

38、ioncurve. 8.2 Calibrationprocedureforthedeterminationofwatercontent 8.2.1 ProcedureA:Threecalibrationsampleswithknownwatercontents Toobtainareliablecalibrationgraph,itisnecessarythatthewatercontentsofthecalibrationsamplesspanthe largestpossiblerange.However,azerowatercontentisnotpermissible. Followt

39、hegeneralprocedurespecifiedin8.1.2to8.1.9. 8.2.2 ProcedureB:Onecalibrationsamplewithknownwatercontent NOTE Inthiscalibrationprocedure,thequantityofwaterdetectedbytheNMRspectrometerisvariedbyvaryingtheheight towhichthesampletubesarefilledwiththecalibrationsample. 8.2.2.1 Followthegeneralprocedurespec

40、ifiedin8.1.2to8.1.4. 8.2.2.2 Introduceintothreetaredsampletubes(5.2)portionsofthecalibrationsamplewithknownwater contenttothreedifferentheights,inaccordancewiththemanufacturersinstructions,andweighthem.Notethe correspondingmassesingramsasm 1 ,m 2 andm 3 . Theminimumnumberofcalibrationpointsforestabl

41、ishingthecalibrationcurveisthree. 8.2.2.3 Calculatetherelativewatercontent,w,asapercentagebymass,ofeachofthethreeportionsofthe calibrationsampleasfollows: w mW m 1 1 1 w mW m 2 2 1 w mW m 3 3 1 where m 1 ,m 2 ,m 3 arethemasses,ingrams,ofthethreeportionsofthecalibrationsampleineachofthethree tubes,wh

42、erem 1 isthelargestmass; W isthewatercontent,asapercentagebymass,ofthecalibrationsample,determinedin accordancewithISO771. 8.2.2.4 EnterintotheNMRspectrometerthevalue,m 1 ,ofthemassofthefirstportion. 8.2.2.5 EnterintotheNMRspectrometerthevalue,w 1 ,oftherelativewatercontentofthefirstportion. 8.2.2.6

43、 Insertthetubecontainingthefirstportionofthecalibrationsampleintothemeasuringheadandcarry outthedetermination. BS 4325-14:2000 5 8.2.2.7 Repeattheoperationsdescribedin8.2.2.4to8.2.2.6withthetwootherportionsofthecalibration sample,alwaysenteringm 1 instep8.2.2.4andtherespectiverelativewatercontentsw

44、2 andw 3 instep8.2.2.5. 8.2.2.8 Calculatethecalibrationparametersinaccordancewithstep8.1.9. 8.3 Calibrationprocedureforthedeterminationofoilcontent 8.3.1 ProcedureA:Threecalibrationsampleswithknownoilcontents Usethesamplesspecifiedin4.3. Followthegeneralprocedurespecifiedin8.1.2to8.1.10. 8.3.2 Proce

45、dureB:Onecalibrationsamplewithknownoilcontent NOTE Inthiscalibrationprocedure,thequantityofoildetectedbytheNMRspectrometerisvariedbyvaryingtheheightto whichthesampletubesarefilledwiththecalibrationsample. 8.3.2.1 Followthegeneralprocedurespecifiedin8.1.2. 8.3.2.2 Introduceintothreetaredsampletubes(5

46、.2)thecalibrationsamplewithknownoilcontenttothree differentheightsinaccordancewiththemanufacturersinstructionsandweigh.Notethecorrespondingmassesin gramsasm 1 ,m 2 andm 3 . 8.3.2.3 Calculatetherelativeoilcontent,h,asapercentagebymass,inthethreeportionsofthecalibration sampleasfollows: h mH m 1 1 1 h

47、 mH m 2 2 1 h mH m 3 3 1 where m 1 ,m 2 ,m 3 arethemasses,ingrams,ofthethreeportionsofthecalibrationsample; H istheoilcontent,asapercentagebymass,ofthecalibrationsample,determinedinaccordance withISO734,part1or2. 8.3.2.4 Followthegeneralprocedurespecifiedin8.1.3to8.1.9,enteringthevalueoftheoilconten

48、t,ingrams, instep8.1.6. 8.3.2.5 EnterintotheNMRspectrometerthevalue,m 1 ,ofthemassofthefirstportion. 8.3.2.6 EnterintotheNMRspectrometerthevalue,h 1 ,oftherelativeoilcontentofthefirstportion. 8.3.2.7 Insertthetubecontainingthefirstportionofthecalibrationsampleintothemeasuringheadandcarry outthedeter

49、mination. 8.3.2.8 Repeattheoperationsdescribedin8.3.2.5to8.3.2.7withthetwootherportionsofthecalibration sample,alwaysenteringm 1 instep8.3.2.5,thentherespectiverelativeoilcontentsh 2 andh 3 instep8.3.2.6. BS 4325-14:20006 8.3.2.9 Toobtainthezero-pointonthecalibrationcurve,enterintotheNMRspectrometerthevalue,m 1 ,ofthe mass,andarelativeoilcontentof0,01%.Insertanemptytubeintothemeasuringheadandcarryoutthe determination. 8.3.2.10 Calculatethecalibrationparametersinaccordancewith8.1.9. 9 Procedure 9.1 General Carryoutat