ISO 2447-1998 Fruit and vegetable products - Determination of tin content《水果和蔬菜制品 锡含量的测定》.pdf

1、A Referencenumbe r ISO2447:1998 (E) INTERNATIONAL STANDARD ISO 2447 Secondedition 19980801 Fruitandvegetableproducts Determinationoftincontent ProduitsdrivsdesfruitsetlgumesDterminationdelateneur entainISO2447:1998(E) ISO1998 Allrightsreserved.Unlessotherwisespecified,nopartofthispublicationmayberep

2、roducedorutilizedinanyformorbyan ymeans,electronic ormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromthepublisher. InternationalOrganizationforStandardization Casepostale56 CH1211Genve20 Switzerland Internet iso.ch PrintedinSwitzerland ii Foreword ISO(theInternationalOrgan

3、izationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISO memberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnical committees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishedhas therighttoberepresentedonthatcommi

4、ttee.Internationalorganizations,governmentalandnongovernmental,in liaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnical Commission(IEC)onallmattersofelectrotechnicalstandardization. DraftInternationalStandardsadoptedbythetechnicalcommitteesarecirculatedtothe

5、memberbodiesforvoting. PublicationasanInternationalStandardrequiresapprovalbyatleast75%ofthememberbodiescastingavote. InternationalStandardISO2447waspreparedbyTechnicalCommitteeISO/TC34, Agriculturalfoodproducts, SubcommitteeSC3, Fruitandvegetableproducts . Thissecondeditioncancelsandreplacesthefirs

6、tedition(ISO2447:1974),whichhasbeentechnicallyrevised.INTERNATIONALSTANDARD ISO ISO2447:1998(E) 1 FruitandvegetableproductsDeterminationoftincontent 1Scope ThisInternationalStandardspecifiesamethodforthedeterminationofthetincontentinfruitandvegetable products. Themethodisapplicabletoproductswhichmay

7、contain,perkilogram,upto: 1,25gofcopper; 0,6goflead; 6gofzinc; 40gofphosphorus. 2Normative reference Thefollowingstandardcontainsprovisionswhich,throughreferenceinthistext,constituteprovisionsofthis InternationalStandard.Atthetimeofpublication,theeditionindicatedwasvalid.Allstandardsaresubjectto rev

8、ision,andpartiestoagreementsbasedonthisInternationalStandardareencouragedtoinvestigatethe possibilityofapplyingthemostrecenteditionofthestandardindicatedbelow.MembersofIECandISOmaintain registersofcurrentlyvalidInternationalStandards. ISO5515:1979,Fruits,vegetablesandderivedproductsDecompositionofor

9、ganicmatterpriortoanalysis Wetmethod. 3Principle Afterdestructionoftheorganicmatterbymeansofsulfuricandnitricacids,andconversionofthetintothestannic form,acomplexisformedinabufferedsolutionofpH1,0topH1,2theiron( III)beingmasked,ifnecessary,by reductionwithascorbicacid.Thecomplexiscolouredorangewithp

10、henylfluoroneandthecolourcomparedwith thoseobtainedunderthesameconditionsbutstartingfromstandardsolutionsofpuretin. 4Reagents Useonlyreagentsofrecognizedanalyticalgrade,anddistilledordemineralizedwaterorwaterofequivalentpurity. 4.1 Sulfuricacid , r 20 =1,84g/ml. 4.2 Dilutesulfuricacid ,1,25mol/l. 4.

11、3 Ascorbicacid ,50g/lsolution. 4.4 Nitricacid , r 20 =1,42g/ml.ISO2447:1998(E) ISO 2 4.5 Hydrochloricacid , r 20 =1,19g/ml. 4.6 Methanol. 4.7 Ethanol,95%( V/V). 4.8 Poly(vinylalcohol) ,16g/lsolution. Dissolve1,6gofpoly(vinylalcohol)inalittlewaterwithgentlewarmingandagitation.Diluteto100mlaftercoolin

12、g. 4.9 Buffersolution ,containing450gofsodiumacetate(CH 3 COONa)and240mlofaceticacid(CH 3 COOH)per litre. 4.10 Tin,standardvolumetricsolution I,containing500 m g/mlinasulfuricacidmedium,approximately3mol/l. Dissolve,withheating,0,5gofpuretininamixtureof50mlofsulfuricacid(4.1),5mlofnitricacid(4.4)and

13、25ml ofwater.Aftercompletesolution,oxidizethetintothestannicformbyboilinguntilwhitefumesappear. Coolthesolutionandpouritintoa1000mlvolumetricflaskcontaining116mlofsulfuricacid(4.1)and100mlof water.Coolanddiluteto1000mlwithwater. NOTE Alternatively,thetinstandardsolutionI(4.10)maybepreparedbydilution

14、ofasuitableproprietarystandard solution. 4.11 Tin,standardvolumetricsolutionII,containing10m g/mlinasulfuricacidmedium,approximately 0,25mol/l. Transfer20mlofthetinstandardvolumetricsolution I(4.10)toa1000mlvolumetricflask.Add10mlofsulfuric acid(4.1)anddiluteto1000mlwithwater. 4.12 Phenylfluoronerea

15、gent (2,6,7trihydroxy9phenyl3isoxathone). Dissolve0,1gofphenylfluoronein10mlofmethanol(4.6)and1mlofhydrochloricacid(4.5)ina500mlvolumetric flask.Dilutetothemarkwithethanol(4.7). Thereagentshallbestoredinabrownbottleinthedark.Itisrecommendedthatitshouldnotbestoredforlonger than1week. 5Apparatus Usual

16、laboratoryapparatusand,inparticular,thefollowing. 5.1 Onemarkvolumetricflasks ,ofcapacity50ml,200mland500ml. 5.2 Pipettes, fordelivering1ml,2ml,3ml,4ml,5ml,10mland20ml. 5.3 Spectrophotometerorphotocolorimeter,withgreenfilter,fittedwithacellof10mmlightpath,enabling measurementstobemadeatwavelengthsfr

17、om500nmto530nm. 5.4 Analyticalbalance, capableofweighingtothenearest0,001g. 6Sampling Itisimportantthatthelaboratoryreceiveasamplewhichistrulyrepresentativeandhasnotbeendamagedor changedduringtransportorstorage.ISO ISO2447:1998(E) 3 SamplingisnotpartofthemethodspecifiedinthisInternationalStandard.As

18、thereisnospecificInternational Standarddealingwithfruitandvegetableproducts,itisrecommendedthatthepartiesconcernedcometoan agreementonthesubject. 7Procedure 7.1 Preparationoftestportion ProceedasdescribedinISO5515,preferablyweighingamassofabout10gtothenearest0,01g. 7.2 Destructionoforganicmatter Pro

19、ceedasdescribedinISO5515. Add5mlofsulfuricacid(4.1)totheresultingsolution.Coolandpouritintoa200mlvolumetricflask(5.1),and dilutetothemarkwithwater(solutionA). 7.3Determination 7.3.1 Bymeansofapipette(5.2),transfertoa50mlvolumetricflask(5.1)anappropriatevolumeofsolutionA,i.e. 20ml,ifthetincontentofth

20、esampleisbelow50mg/kg; 10ml,ifthetincontentofthesampleisbetween50mg/kgand125mg/kg,dilutingto20mlwithdilutesulfuric acid(4.2); 5ml,ifthetincontentofthesampleisabove125mg/kg,dilutingto20mlwithdilutesulfuricacid(4.2). 7.3.2 Thenaddinsuccession: 10mlofbuffersolution(4.9); 1mlofascorbicacidsolution(4.3);

21、 1) 5mlofpoly(vinylalcohol)solution(4.8); 5mlofphenylfluoronereagent(4.12). Swirltheflask,avoidingfoamformationfromthepoly(vinylalcohol).Leavetostandfor5min. Dilutetothemarkwithwaterandleavetostandfor30min.Thencarryoutthemeasurementatawavelengthof 505nminthespectrophotometerorphotocolorimeter(5.3).

22、7.3.3 Carryouttwodeterminationsonthesamepreparedsampletakenforthedestructionoforganicmatter (solutionA)(see7.2). 7.4 Preparationofcalibrationcurve 7.4.1 Intoaseriesofsix50mlvolumetricflasks(5.1),eachcontaining20mlofdilutesulfuricacid(4.2),addthe followingvolumesofstandardvolumetrictinsolution II(4.1

23、1): 0ml,equivalentto0 m goftin 1ml,equivalentto10 m goftin 2ml,equivalentto20 m goftin 1)Theadditionofascorbicacidisnotnecessaryifthecontentofiron( III)isequaltoorlessthan25mg/kg.ISO2447:1998(E) ISO 4 3ml,equivalentto30 m goftin 4ml,equivalentto40 m goftin 5ml,equivalentto50 m goftin 7.4.2 Thenproce

24、edasindicatedin7.3.2. 7.4.3 Preparethecalibrationcurve,showingthedifferenceofopticaldensityasafunctionofthenumberof microgramsoftin. 8 Expressionofresults Bymeansofthecalibrationcurve,convertthefigureobtainedin7.3.2intomicrogramsoftin. Thetincontent,expressedinmilligramsperkilogramofproduct,isequalt

25、o m Vm m Vm 1 0 1 0 1000 200 1000 200 = where m 0 isthemass,ingrams,ofthetestportion; m 1 isthemassoftin,inmicrograms,readfromthecalibrationcurve; V isthevolume,inmillilitres,ofsolutionAtakenforcolorimetricmeasurement(see7.3.1). Takeastheresultthearithmeticmeanoftheresultsofthetwodeterminations(7.3.

26、3),providedthattheirdifference doesnotexceed5%ofthearithmeticmean. 9Repeatability Theabsolutedifferencebetweentwoindependentsingletestresults,obtainedusingthesamemethodonidentical testmaterialinthesamelaboratorybythesameoperatorusingthesameequipmentwithinashortintervaloftime, willinnotmorethan5%ofca

27、sesbegreaterthan5%ofthearithmeticmeanofthetworesults. Rejectbothresultsifthedifferenceexceeds5 %ofthearithmeticmeanandcarryouttwonewsingle determinations. 10Test report Thetestreportshallspecify: allinformationnecessaryforthecompleteidentificationofthesample; thesamplingmethodused,ifknown; thetestme

28、thodused,togetherwithreferencetothisInternationalStandard; alloperatingdetailsnotspecifiedinthisInternationalStandard,orregardedasoptional,togetherwithdetailsof anyincidentswhichmayhaveinfluencedthetestresult(s); thetestresult(s)obtained; iftherepeatabilityhasbeenchecked,thefinalquotedresultobtained.ISO2447:1998(E) ISO ICS67.080.01 Descriptors: agriculturalproducts,foodproducts,plantproducts,fruitandvegetableproducts,chemicalanalysis,determinationofco ntent, tin,colorimetricanalysis. Pricebasedon4pages